Python module for near field communication¶
Release v0.9.2
The nfcpy module implements NFC Forum specifications for wireless short-range data exchange with NFC devices and tags. It is written in Python and aims to provide an easy-to-use yet powerful framework for Python applications. The software is licensed under the EUPL.
To send a web link to a smartphone:
>>> import nfc, nfc.snep, threading
>>> connected = lambda llc: threading.Thread(target=llc.run).start()
>>> uri = nfc.ndef.Message(nfc.ndef.UriRecord("http://nfcpy.org"))
>>> clf = nfc.ContactlessFrontend('usb')
>>> llc = clf.connect(llcp={'on-connect': connected})
>>> nfc.snep.SnepClient(llc).put(uri)
True
>>> clf.close()
Overview¶
Requirements¶
- Python 2.6 or newer but not Python 3.x
- pyUSB and libusb (for native USB readers)
- pySerial (for serial readers on COM or USB)
Supported Hardware¶
- Sony RC-S330/360/370/380
- SCM SCL-3710/11/12
- ACS ACR122U (version 2.xx)
- Arygon APPBUS
- Stollmann NFC Reader
Notes:
- All readers are tested to work with Ubuntu Linux. Less frequently some are tested to work on Windows (usually the SCL3711 and RC-S3xx). User feedback indicates that the readers seem to work on Mac. Readers with serial communication protocol have not yet been tested on Windows.
- The Sony RC-S380 is the only reader for which nfcpy currently supports tag emulation, more specifically Type 3 Tag emulation.
- The NXP PN53x can not properly handle Type 1 Tags with dynamic memory layout (Topaz 512) due to a firmware bug that does not allow READ-8 and WRITE-8 commands to be executed.
- The NXP PN531 chip does not support any Type 1 Tag command and is also not able to exchange Type 4 Tag commands if the ReadBinary and UpdateBinary commands exceed the length of a standard host controller frame (which may happen if the card sets ISO-DEP MIU as 256).
- The ACR122U is disabled as P2P Listener because the listen time can not be set less than 5 seconds. Also, because the reader has an MCU that controls a PN532 to implement the USB CCID protocol, it is generally less usable for NFC P2P communication due to the MCU interfering with settings made directly to the PN532.
Implementation Status¶
Specification | Status |
---|---|
TS NFC Digital Protocol 1.0 | except Type B |
TS NFC Activity 1.0 | except Type B |
TS Type 1 Tag Operation 1.1 | implemented |
TS Type 2 Tag Operation 1.1 | implemented |
TS Type 3 Tag Operation 1.1 | implemented |
TS Type 4 Tag Operation 1.0 | implemented |
TS Type 4 Tag Operation 2.0 | implemented |
TS NFC Data Exchange Format 1.0 | except chunking |
TS NFC Record Type Definition 1.0 | implemented |
TS Text Record Type 1.0 | implemented |
TS URI Record Type 1.0 | implemented |
TS Smart Poster Record Type 1.0 | implemented |
TS Signature Record Type 1.0 | not implemented |
TS Logical Link Control Protocol 1.1 | implemented |
TS Simple NDEF Exchange Protocol 1.0 | implemented |
TS Connection Handover 1.2 | implemented |
TS Personal Health Communication 1.0 | implemented |
AD Bluetooth Secure Simple Pairing | implemented |
References¶
- NFC Forum Specifications: http://www.nfc-forum.org/specs/
Getting started¶
Installation¶
1. Get the code
To get the latest development version:
$ sudo apt-get install bzr
$ cd <somedir>
$ bzr branch lp:nfcpy
This will download a branch of the nfcpy trunk repository from
Canonical’s Launchpad source code hosting platform into the local
directory <somedir>/trunk
.
For a Windows install the easiest is to download the Bazaar standalone
installer from http://wiki.bazaar.canonical.com/WindowsDownloads and
choose the Typical Installation that includes the Bazaar Explorer
GUI Application. Start Bazaar Explorer, go to Get project source
from elsewhere and create a local branch of lp:nfcpy
into
C:/src/nfcpy
or some other directory of choice.
A release versions can be branched from the appropriate series, for example to grab the latest 0.0.x release.:
$ bzr branch lp:nfcpy/0.9
Tarballs of released versions are available for download at https://launchpad.net/nfcpy.
2. Install Python
Python is already installed on every Desktop Linux. Windows installers can be found at http://www.python.org/download/windows/. Make sure to choose a 2.x version, usually the latest, as nfcpy is not yet ported to Python 3.
3. Install libusb
The final piece needed is the USB library libusb and Python bindings. Once more this is dead easy for Linux where libusb is already available and the only step required is:
$ sudo apt-get install python-usb
To install libusb for Windows read the Driver Installation at
http://www.libusb.org/wiki/windows_backend and use Zadig.exe to
install libusb-win32 for the contactless reader device (connect the
reader and cancel the standard Windows install dialog, the device will
be selectable in Zadig). The Python USB library can be downloaded as
a zip file from http://sourceforge.net/projects/pyusb/ and installed
with python.exe setup.py install
from within the unzipped pyusb
source code directory (add the full path to python.exe if it’s not
part of the search path).
4. Run example
A couple of example programs come with nfcpy. To see if the installation succeeded and the reader is working head over to the nfcpy directory and run the tagtool example:
$ python examples/tagtool.py show
Touch a compatible tag (NFC Forum Type 1-4) and the NDEF data should be printed. See tagtool.py for other options.
Note
Things may not immediately work on Linux for two reasons:
The reader might be claimed by the Linux NFC subsystem available
since Linux 3.1 and root privileges may be required to access the
device. To prevent a reader being used by the NFC kernel driver add
a blacklist entry in '/etc/modprobe.d/'
, for example the following
line works for the PN533 based SCL3711:
$ echo "blacklist pn533" | sudo tee -a /etc/modprobe.d/blacklist-nfc.conf
Root permissions are usually needed for the USB readers and sudo
python
is an easy fix, however not quite convinient and
potentially dangerous. A better solution is to add a udev rule and
make the reader accessible to a normal user, like the following
rules would allow members of the plugdev group to access an
SCL-3711 or RC-S380 if stored in
'/etc/udev/rules.d/nfcdev.rules'
.
SUBSYSTEM=="usb", ACTION=="add", ATTRS{idVendor}=="04e6", \
ATTRS{idProduct}=="5591", GROUP="plugdev" # SCM SCL-3711
SUBSYSTEM=="usb", ACTION=="add", ATTRS{idVendor}=="054c", \
ATTRS{idProduct}=="06c1", GROUP="plugdev" # Sony RC-S380
Open a reader¶
The main entrance to nfcpy is the nfc.ContactlessFrontend
class. When initialized with a path argument it tries to locate and
open a contacless reader connected at that location, which may be for
example the first available reader on USB.
>>> import nfc
>>> clf = nfc.ContactlessFrontend('usb')
>>> print(clf)
Sony RC-S360/SH on usb:002:005
For more control of where a reader may befound specifiy further details of the path string, for example usb:002:005 to open the same reader as above, or usb:002 to open the first available reader on USB bus number 2 (same numbers as shown by the lsusb command). The other way to specify a USB reader is by vendor and product ID, again by way of example usb:054c:02e1 will most likely open the same reader as before if there’s only one plugged in.
>>> import nfc
>>> clf = nfc.ContactlessFrontend('usb:054c')
>>> print(clf)
Sony RC-S360/SH on usb:002:005
If you don’t have an NFC reader at hand or just want to test your application logic a driver that carries NFC frames across a UDP/IP link might come handy.
>>> import nfc
>>> clf = nfc.ContactlessFrontend('udp')
>>> print(clf)
Linux UDP/IP on udp:localhost:54321
Just to say for completeness, you can also omit the path argument and
later open a reader using ContactlessFrontend.open()
. The
difference is that open()
returns either
True
or False
depending on whether a reader was
found whereas ContactlessFrontend('...')
raises IOError
if a reader was not found.
Read/write tags¶
With a reader opened the next step to get an NFC communication running
is to use the nfc.clf.ContactlessFrontend.connect()
method.
We’ll start with connecting to a tag (a contactless card), hopefully
you have one and it’s not a Mifare Classic. Currently supported are
only NFC Forum Type 1, 2, 3 and 4 Tags.
>>> import nfc
>>> clf = nfc.ContactlessFrontend('usb')
>>> clf.connect(rdwr={}) # now touch a tag and remove it
True
Although this doesn’t look very exciting a lot has happened in the
background. The tag was discovered and activated and it’s data content
read. Thereafter nfc.clf.ContactlessFrontend.connect()
continued
to check the presence of the tag until you removed it. The return
value True
tells us that it terminated normally and not
due to a KeyboardInterrupt
(in which case we’ve seen
False
). You can try this by either not touching or not
removing the tag and press Ctrl-C while in connect()
.
Obviously, as we’ve set the rdwr options as a dictionary, there must be something we can put into the dictionary to give us a bit more control. The most important option we can set is a callback funtion that will let us know when a tag got connected. It’s famously called ‘on-connect’ and can be used like so:
>>> import nfc
>>> def connected(tag): print tag
...
>>> clf = nfc.ContactlessFrontend('usb')
>>> clf.connect(rdwr={'on-connect': connected}) # now touch a tag
Type3Tag IDm=01010501b00ac30b PMm=03014b024f4993ff SYS=12fc
<nfc.tag.tt3.Type3Tag object at 0x7f9e8302bfd0>
As expected our simple callback function does print some basic
information about the tag, we see that it was an NFC Forum Type 3 Tag
which has the system code 12FCh, a Manufacture ID and Manufacture
Parameters. You should have noted that the connect() was not blocking
until the tag was removed and that we’ve got an instance of class
nfc.tag.tt3.Type3Tag
returned. Both is because the callback
function did return None
(treated as False
internally) and the connect() logic assumed that the caller want’s to
handle the tag presence check by itself or explicitely does not want
to have that loop running. If we slightly modify the example you’ll
notice that again you have to remove the tag before connect() returns
and the return value now is True
(unless you press
Control-C
of course).
>>> import nfc
>>> def connected(tag): print tag; return True
...
>>> clf = nfc.ContactlessFrontend('usb')
>>> clf.connect(rdwr={'on-connect': connected}) # now touch a tag
Type3Tag IDm=01010501b00ac30b PMm=03014b024f4993ff SYS=12fc
True
Note
The generally recommended way for application logic on top of nfcpy is to use callback functions and not manually deal with the objects returned by connect(). But in the interactive Python interpreter it is sometimes just more convinient to do so. Tags are also quite friendly, they’ll just wait indefinite time for you to send them a command, this is much different for LLCP and CARD mode where timing becomes critical. But more on that later.
Now that we’ve seen how to connect a tag, how do we get some data from it? If using the same tag as before, we’ve already learned by the system code 12FCh (which is specific for Type 3 Tags) that this tag should be capable to hold an NDEF message (NDEF is the NFC Forum Data Exchange Format and can be read and written with every NFC Forum compliant Tag). As nfcpy is supposed to make things easy, here is the small addition we need to get the NDEF message printed.
>>> import nfc
>>> with nfc.ContactlessFrontend('usb') as clf:
... tag = clf.connect(rdwr={'on-connect': None}) # now touch a tag
... print tag.ndef.message.pretty() if tag.ndef else "Sorry, no NDEF"
...
record 1
type = 'urn:nfc:wkt:Sp'
name = ''
data = '\xd1\x01\nU\x03nfcpy.org'
If the tag’s attribute ndef
is set we can simply read
the ndef message
attribute to get a fully parsed
nfc.ndef.Message
object, which in turn has a method to pretty
print itself. It looks like this is a Smartposter message and probably
links to the nfcpy website.
Note
We used two additional features to make our life easier and
shorten typing. We’ve set the ‘on-connect’ callback to simply
None
instead of providing an actual function object that
returns None
(or False
which would have the same
effect). And we used ContactlessFrontend
as a context
manager, which means the clf it will be closed as soon as we
leave the with clause.
Let’s see if the Smartposter message is really referring to
nfcpy.org
. For that we’ll need to know that NDEF parsers and
generators are in the submodule nfc.ndef
. And because it’s easier
to observe results step-by-step we’ll not use the context manager
mechanism but go plain. Just don’t forget that you have either close
the clf at the end of the example or leave the interpreter before
trying the next example
>>> import nfc
>>> clf = nfc.ContactlessFrontend('usb')
>>> tag = clf.connect(rdwr={'on-connect': None}) # now touch a tag
>>> if tag.ndef and tag.ndef.message.type == 'urn:nfc:wkt:Sp':
... sp = nfc.ndef.SmartPosterRecord(tag.ndef.message[0])
... print sp.pretty()
...
resource = http://nfcpy.org
action = default
There are a few things to note. First, we went one step further in
attribute the hierarchy and discovered the message type. An
nfc.ndef.Message
is a sequence of nfc.ndef.Record
objects, each having a type, a name and a data member. The
type and name of the first record are simply mapped to the type
and name of the message itself as that usually sets the processing
context for the remaining records. Second, we grab the first record by
index 0 without any check for an index error. Of course may that be
safe due to the initial check on message type (which turns to the
first record type) and we’d expect something else to be there if the
message is empty. But it’s also safe because the tag.ndef.message
will always hold a valid Message
, just that it
be a message with one empty record (type, name and data will all
be empty strings) if the NDEF tag does not contain actual NDEF data or
the data is corrupted.
Now as the final piece of this section let us improve the Smartposter a little bit. Usually a Smartposter should have a URI that links to the resource and a title to help humans understand what the link points to. We omit all the safety check, so please be sure to touch the same tag as before and not switch to a Mifare Classic.
>>> import nfc
>>> clf = nfc.ContactlessFrontend('usb')
>>> tag = clf.connect(rdwr={'on-connect': None}) # now touch the tag
>>> sp = nfc.ndef.SmartPosterRecord('http://nfcpy.org')
>>> sp.title = "Python module for near field communication"
>>> tag.ndef.message = nfc.ndef.Message(sp)
>>> print nfc.ndef.SmartPosterRecord(tag.ndef.message[0]).pretty()
resource = http://nfcpy.org
title[en] = Python module for near field communication
action = default
It happend, you’ve destroyed your overly expensive contactless
tag. Sorry I was joking, except for the “overly expensive” part (they
should really become cheaper). But the tag, if nothing crashed, has
now slightly different content and it all happend in the sixth line
were the new message got assigned to the tag.ndef.message
attribute. In that line it was immediately written to the tag and the
internal copy (the old data) invalidated. The last line then caused
the message to be read back from the tag and finally printed.
Note
The nfc.ndef
module has a lot more functionality than
could be covered in this short introduction, feel free to read the
API documentation as well as the NFC Data Exchange Format tutorial to
learn how nfcpy maps to the concepts of the NDEF specification.
Pretend a card¶
How do we get nfcpy to be a card? Supply card
options to
nfc.ContactlessFrontend.connect()
.
>>> import nfc
>>> clf = nfc.ContactlessFrontend('usb')
>>> print clf.connect(card={})
None
Guess you’ve noticed that something was going wrong. Unlike when
reading a card (or tag) the clf.connect()
call returns immediately
and the result we’re getting is None
. This is because there
exists no sensible default behavior that can be applied when working
as a tag, we need to be explicit about the technology we want to use
(for a tag reader it just makes sense to look for all technologies and
tag types). So we choose a technology and supply that as the ‘targets’
option.
>>> import nfc
>>> clf = nfc.ContactlessFrontend('usb')
>>> nfcf_idm = bytearray.fromhex('03FEFFE011223344')
>>> nfcf_pmm = bytearray.fromhex('01E0000000FFFF00')
>>> nfcf_sys = bytearray.fromhex('12FC')
>>> target = nfc.clf.TTF(br=212, idm=nfcf_idm, pmm=nfcf_pmm, sys=nfcf_sys)
>>> clf.connect(card={'targets': [target]}) # touch a reader
True
Note
It is time to talk about the limitations. As of writing,
nfcpy supports tag emulation only for NFC Forum Type 3 Tag and
requires a Sony RC-S380 contactless frontend. The only alternative
to an RC-S380 is to use the UDP driver that simulates NFC
communication over UDP/IP. To use the UDP driver initialize
ContactlessFrontend with the string udp
and use
examples/tagtool.py --device udp
as card reader.
You can read the tag we’ve created for example with the excellent NXP Tag Info app available for free in the Android app store. It will tell you that this is a FeliCa Plug RC-S926 tag (because we said that with the first two bytes of the IDm) and if you switch over to the TECH view there’ll be the IDm, PMm and System Code we’ve set.
Note
Depending on your Android device it will be more or less difficult to get a stable reading, it seems to depend much on the phone’s NFC chip and driver. Generally the Google Nexus 4 and 10 work pretty well and the same should be true for the Samsung S4 as those are having the same chip. Other phones can be a little bitchy.
The NXP Tag Info app tells us that there’s no NDEF partition on it, so let’s fix that. It’s unfortunately now going to be a bit more code and you probably want to copy it, so the following is not showing the interpreter prompt.
import nfc
clf = nfc.ContactlessFrontend('usb')
nfcf_idm = bytearray.fromhex('03FEFFE011223344')
nfcf_pmm = bytearray.fromhex('01E0000000FFFF00')
nfcf_sys = bytearray.fromhex('12FC')
target = nfc.clf.TTF(br=212, idm=nfcf_idm, pmm=nfcf_pmm, sys=nfcf_sys)
attr = nfc.tag.tt3.NdefAttributeData()
attr.version, attr.nbr, attr.nbw = '1.0', 12, 8
attr.capacity, attr.writeable = 1024, True
ndef_data_area = str(attr) + bytearray(attr.capacity)
def ndef_read(block_number, rb, re):
if block_number < len(ndef_data_area) / 16:
first, last = block_number*16, (block_number+1)*16
block_data = ndef_data_area[first:last]
return block_data
def ndef_write(block_number, block_data, wb, we):
global ndef_data_area
if block_number < len(ndef_data_area) / 16:
first, last = block_number*16, (block_number+1)*16
ndef_data_area[first:last] = block_data
return True
def connected(tag, cmd):
tag.add_service(0x0009, ndef_read, ndef_write)
tag.add_service(0x000B, ndef_read, lambda: False)
return True
while clf.connect(card={'targets': [target], 'on-connect': connected}): pass
We’ve now got a fully functional NFC Forum Type 3 Tag. If, for
example, you have the NXP Tag Writer app installed, start to write
something to the card, touch again to read it back, and so
on. Finally, press Ctrl-C
to stop the card working.
Note
Other card commands can be realized by running the basic
receive command and send response loop as part of the
application logic, for example as part of the on-connect
callback function with a False
value returned at the
end. The loop requires a bit of exception checking and must handle
unknown command, check out nfc.ContactlessFrontend.connect()
in nfc/clf.py
for something to start with.
Work with a peer¶
The best part of NFC comes when the limitations of a single master controlling a poor servant are overcome. This is achieved by the NFC Forum Logical Link Control Protocol (LLCP), which allows multiplexed communications between two NFC Forum Devices with either peer able to send protocol data units at any time and no restriction to a single application run in one direction.
An LLCP link between two NFC devices is established again by calling
ContactlessFrontend.connect()
with a set of options, this time
they go with the argument llcp
.
Note
The example code in this section assumes that you have an
Android phone to use as peer device. If that is not the case you
can either use readers that are supported by nfcpy and start
examples/snep-test-server.py --loop
before diving into the
examples or use the UDP driver to work without a hardware. You’ll
then start examples/snep-test-server.py --loop --device udp
first and initalize ContactlessFrontend()
with the path
string 'udp'
instead of 'usb'
.
Here’s the shortest code fragment we can use to get an LLCP link running.
>>> import nfc
>>> clf = ContactlessFrontend('usb')
>>> clf.connect(llcp={}) # now touch your phone
True
>>> clf.close()
Depending on your reader and the phone you may have had to explicitely
move both out of proximity to see True
printed after connect
or it may just have happened. That is simply because the device
connect phase may have seen unstable communication and connect
returns after one activation/deactivation.
Note
In the contactless world it can not be really distinguished whether deactivation was intentional deactivation or because of broken communication. A broken communication is just the normal case when a user removes the device.
Remember that connect()
returns
True
(or something that evaluates True
in a boolean
expression) when returning normally and the pattern is clear: We just
need to call connect()
in an endless loop
until a KeyboardInterrupt
exception is raised (with Ctrl-C
or send by an external program)
>>> import nfc
>>> clf = ContactlessFrontend('usb')
>>> while clf.connect(llcp={}): pass
...
>>> clf.close()
Now we’ve got LLCP running but there’s still not much we can do with
it. But same as for the other modes we can add a callback function for
the on-connect
event. This function will receive as it’s single
argument the LogicalLinkController
instance
that controls the LLCP link.
>>> import nfc
>>> def connected(llc):
... print llc
... return True
...
>>> clf = ContactlessFrontend('usb')
>>> clf.connect(llcp={'on-connect': connected})
LLC: Local(MIU=128, LTO=100ms) Remote(MIU=1024, LTO=500ms)
True
>>> clf.close()
The callback function is the place where we to start LLCP client and
server applications but it is important to treat it like an interrupt,
that means application code must be started in a separate thread and
the callback return immediately. The reason is that in order to keep
the LLCP link alive and receive or dispatch LLC protocol data units
(PDUs) the LogicalLinkController
must run a
service loop and connect()
is using the
calling thread’s context for that. When using the interactive
interpreter this is less convinient as we’d have to change the
callback code when going further with the tutorial, so remember that
if the callback returns False
or None
then
connect()
will not do the housekeeping
stuff but return immediately and give us the callback parameters.
>>> import nfc, threading
>>> clf = nfc.ContactlessFrontend('usb')
>>> connected = lambda llc: threading.Thread(target=llc.run).start()
>>> llc = clf.connect(llcp={'on-connect': connected})
>>> print llc
LLC: Local(MIU=128, LTO=100ms) Remote(MIU=1024, LTO=500ms)
>>> clf.close()
Application code is not supposed to work directly with the llc
object but it’s one of the parameters we need to create a
nfc.llcp.Socket
for the actual communication. The other
parameter we need to supply is the socket type, either
nfc.llcp.LOGICAL_DATA_LINK
for a connection-less socket or
nfc.llcp.DATA_LINK_CONNECTION
for a connection-mode socket. A
connection-less socket does not guarantee that application data is
delivered to the remote application (although nfcpy makes sure that
it’s been delivered to the remote device). A connection-mode socket
cares about reliability, unless the other implementation is buggy data
you send is guaranteed to make it to the receiving application -
error-free and in order.
So what can we do next with the Android phone? It happens that every modern NFC phone on the market has a so called SNEP Default Server running that we can play with. The acronym SNEP stands for the NFC Forum Simple NDEF Exchange Protocol and the SNEP Default Server is a service that must be available on every NFC Forum certified device. Though many phones are not yet certified, a SNEP default server is built into stock Android as part of the Android Beam feature. Because SNEP messages are exchanged over an LLCP data link connection we’ll first have to create a connection-mode socket, then determine the address of the SNEP server, connect to the server and finally send some data.
>>> import nfc, threading
>>> clf = nfc.ContactlessFrontend('usb')
>>> connected = lambda llc: threading.Thread(target=llc.run).start()
>>> llc = clf.connect(llcp={'on-connect': connected})
>>> socket = nfc.llcp.Socket(llc, nfc.llcp.DATA_LINK_CONNECTION)
>>> addr = socket.resolve('urn:nfc:sn:snep')
>>> addr
4
>>> socket.connect(addr)
>>> msg = nfc.ndef.Message(nfc.ndef.SmartPosterRecord("http://nfcpy.org"))
>>> str(msg)
'\xd1\x02\x0eSp\xd1\x01\nU\x03nfcpy.org'
>>> hex(len(str(msg)))
'0x13'
>>> socket.send("\x10\x02\x00\x00\x00\x13" + str(msg))
>>> socket.recv()
'\x10\x81\x00\x00\x00\x00'
>>> socket.close()
>>> clf.close()
If your phone has an Internet connection you should now see that the Internet browser has opened the http://nfcpy.org web page. In Android terminology we’ve beamed.
Just for the purpose of demonstration the example did resolve the SNEP
default server’s service name into an address value first. But both
the service name urn:nfc:sn:snep
and the address 4 are well-known
values defined in the NFC Forum Assigned Numbers Register and so
we’ve could have directly connect to address 4. And because it is also
possible to use a service name as an address we’ve could have gone
without the reolve step at all. So all of the following calls would have brought us the same effect.
>>> socket.connect( socket.resolve('urn:nfc:sn:snep') )
>>> socket.connect( 'urn:nfc:sn:snep' )
>>> socket.connect( 4 )
As it is a primary goal of nfcpy to make life as simple as possible,
there is no need to mess around with binary strings. The
nfc.snep.SnepClient
does all the things needed, just import
nfc.snep
to have it available.
>>> import nfc, nfc.snep, threading
>>> clf = nfc.ContactlessFrontend('usb')
>>> connected = lambda llc: threading.Thread(target=llc.run).start()
>>> llc = clf.connect(llcp={'on-connect': connected})
>>> link = nfc.ndef.UriRecord("http://nfcpy.org")
>>> snep = nfc.snep.SnepClient(llc)
>>> snep.put(nfc.ndef.Message(link))
True
>>> clf.close()
The nfc.llcp
module documentation contains more information on
LLCP and the nfc.llcp.Socket
API.
NFC Data Exchange Format¶
NDEF (NFC Data Exchange Format) is a binary message format to exchange application-defined payloads between NFC Forum Devices or to store payloads on an NFC Forum Tag. A payload is described by a type, a length and an optional identifer encoded in an NDEF record structure. An NDEF message is a sequence of NDEF records with a begin marker in the first and an end marker in the last record.
NDEF decoding and encoding is provided by the nfc.ndef
module.
>>> import nfc.ndef
Parsing NDEF¶
An nfc.ndef.Message
class can be initialized with an NDEF
message octet string to parse that data into the sequence of NDEF
records framed by the begin and end marker of the first and last
record. Each NDEF record is represented by an nfc.ndef.Record
object accessible through indexing or iteration over the
nfc.ndef.Message
object.
>>> import nfc.ndef
>>> message = nfc.ndef.Message(b'\xD1\x01\x0ET\x02enHello World')
>>> message
nfc.ndef.Message([nfc.ndef.Record('urn:nfc:wkt:T', '', '\x02enHello World')])
>>> len(message)
1
>>> message[0]
nfc.ndef.Record('urn:nfc:wkt:T', '', '\x02enHello World')
>>> for record in message:
>>> record.type, record.name, record.data
>>>
('urn:nfc:wkt:T', '', '\x02enHello World')
An NDEF record carries three parameters for describing its payload:
the payload length, the payload type, and an optional payload
identifier. The nfc.ndef.Record.data
attribute provides access
to the payload and the payload length is obtained by len()
. The
nfc.ndef.Record.name
attribute holds the payload identifier
and is an empty string if no identifer was present in the NDEF
date. The nfc.ndef.Record.type
identifies the type of the
payload as a combination of the NDEF Type Name Format (TNF) field and
the type name itself.
Empty (TNF 0)
An Empty record type (expressed as a zero-length string) indicates that there is no type or payload associated with this record. Encoding a record of this type will exclude the name (payload identifier) and data (payload) contents. This type can be used whenever an empty record is needed; for example, to terminate an NDEF message in cases where there is no payload defined by the user application.
NFC Forum Well Known Type (TNF 1)
An NFC Forum Well Known Type is a URN as defined by RFC 2141, with the namespace identifier (NID) “nfc”. The Namespace Specific String (NSS) of the NFC Well Known Type URN is prefixed with “wkt:”. When encoded in an NDEF message, the Well Known Type is written as a relative-URI construct (cf. RFC 3986), omitting the NID and the “wkt:” -prefix. For example, the type “urn:nfc:wkt:T” will be encoded as TNF 1, TYPE “T”.
Media-type as defined in RFC 2046 (TNF 2)
A media-type follows the media-type BNF construct defined by RFC 2046. Records that carry a payload with an existing, registered media type should use this record type. Note that the record type indicates the type of the payload; it does not refer to a MIME message that contains an entity of the given type. For example, the media type ‘image/jpeg’ indicates that the payload is an image in JPEG format using JFIF encoding as defined by RFC 2046.
Absolute URI as defined in RFC 3986 (TNF 3)
An absolute-URI follows the absolute-URI BNF construct defined by RFC 3986. This type can be used for message types that are defined by URIs. For example, records that carry a payload with an XML-based message type may use the XML namespace identifier of the root element as the record type, like a SOAP/1.1 message may be represented by the URI ‘http://schemas.xmlsoap.org/soap/envelope/‘.
NFC Forum External Type (TNF 4)
An NFC Forum External Type is a URN as defined by RFC 2141, with the namespace identifier (NID) “nfc”. The Namespace Specific String (NSS) of the NFC Well Known Type URN is prefixed with “ext:”. When encoded in an NDEF message, the External Type is written as a relative-URI construct (cf. RFC 3986), omitting the NID and the “ext:” -prefix. For example, the type “urn:nfc:ext:nfcpy.org:T” will be encoded as TNF 4, TYPE “nfcpy.org:T”.
Unknown (TNF 5)
An Unknown record type (expressed by the string “unknown”) indicates that the type of the payload is unknown, similar to the “application/octet-stream” media type.
Unchanged (TNF 6)
An Unchanged record type (expressed by the string “unchanged”) is used in middle record chunks and the terminating record chunk used in chunked payloads. This type is not allowed in any other record.
>>> import nfc.ndef
>>> message = nfc.ndef.Message('\xD0\x00\x00')
>>> nfc.ndef.Message('\xD0\x00\x00')[0].type
''
>>> nfc.ndef.Message('\xD1\x01\x00T')[0].type
'urn:nfc:wkt:T'
>>> nfc.ndef.Message('\xD2\x0A\x00text/plain')[0].type
'text/plain'
>>> nfc.ndef.Message('\xD3\x16\x00http://example.org/dtd')[0].type
'http://example.org/dtd'
>>> nfc.ndef.Message('\xD4\x10\x00example.org:Text')[0].type
'urn:nfc:ext:example.org:Text'
>>> nfc.ndef.Message('\xD5\x00\x00')[0].type
'unknown'
>>> nfc.ndef.Message('\xD6\x00\x00')[0].type
'unchanged'
The type and name of the first record, by convention, provide the
processing context and identification not only for the first record
but for the whole NDEF message. The nfc.ndef.Message.type
and
nfc.ndef.Message.name
attributes map to the type and anme
attributes of the first record in the message.
>>> message = nfc.ndef.Message(b'\xD1\x01\x0ET\x02enHello World')
>>> message.type, message.name
('urn:nfc:wkt:T', '')
If invalid or insufficient data is provided to to the NDEF message parser, an nfc.ndef.FormatError
or nfc.ndef.LengthError
is raised.
>>> try: nfc.ndef.Message('\xD0\x01\x00')
... except nfc.ndef.LengthError as e: print e
...
insufficient data to parse
>>> try: nfc.ndef.Message('\xD0\x01\x00T')
... except nfc.ndef.FormatError as e: print e
...
ndef type name format 0 doesn't allow a type string
Creating NDEF¶
An nfc.ndef.Record
class can be initialized with an NDEF
To build NDEF messages use the nfc.ndef.Record
class to
create records and instantiate an nfc.ndef.Message
object
with the records as arguments.
>>> import nfc.ndef
>>> record1 = nfc.ndef.Record("urn:nfc:wkt:T", "id1", "\x02enHello World!")
>>> record2 = nfc.ndef.Record("urn:nfc:wkt:T", "id2", "\x02deHallo Welt!")
>>> message = nfc.ndef.Message(record1, record2)
The nfc.ndef.Message
class also accepts a list of records as a single argument and it is possible to nfc.ndef.Message.append()
records or nfc.ndef.Message.extend()
a message with a list of records.
>>> message = nfc.ndef.Message()
>>> message.append(record1)
>>> message.extend([record2, record3])
The serialized form of an nfc.ndef.Message
object is produced with str()
.
>>> message = nfc.ndef.Message(record1, record2)
>>> str(message)
'\x99\x01\x0f\x03Tid1\x02enHello World!Y\x01\x0e\x03Tid2\x02deHallo Welt!'
Specific Records¶
Text Record¶
>>> import nfc.ndef
>>> record = nfc.ndef.TextRecord("Hello World!")
>>> print record.pretty()
text = Hello World!
language = en
encoding = UTF-8
Uri Record¶
>>> import nfc.ndef
>>> record = nfc.ndef.UriRecord("http://nfcpy.org")
>>> print record.pretty()
uri = http://nfcpy.org
Smart Poster Record¶
>>> import nfc.ndef
>>> uri = "https://launchpad.net/nfcpy"
>>> record = nfc.ndef.SmartPosterRecord(uri)
>>> record.title = "Python module for near field communication"
>>> record.title['de'] = "Python Modul für Nahfeldkommunikation"
>>> print record.pretty()
resource = https://launchpad.net/nfcpy
title[de] = Python Modul für Nahfeldkommunikation
title[en] = Python module for near field communication
action = default
Logical Link Control Protocol¶
The Logical Link Control Protocol allows multiplexed communications between two NFC Forum Peer Devices where either peer can send protocol data units at any time (asynchronous balanced mode). The communication endpoints are called Service Access Points (SAP) and are addressed by a 6 bit numerical identifier. Protocol data units are exchanged between exactly two service access points, from a source SAP (SSAP) to a destination SAP (DSAP). The service access point address space is split into 3 parts: an address between 0 and 15 identifies a well-known service, an address between 16 and 31 identifies a service that is registered in the local service environment, and addresses between 32 and 63 are unregistered and normally used as a source address by client applications that send or connect to peer services.
The interface to realize LLCP client and server applications in nfcpy
is implemented by the nfc.llcp.Socket
class. A socket is
created with a LogicalLinkController
instance
and the socket type as arguments to the Socket
constructor. The nfc.ContactlessFrontend.connect()
method
accepts callback functions that will receive the active
LogicalLinkController
instance as argument.
import nfc
import nfc.llcp
def client(socket):
socket.sendto("message", address=16)
def connected(llc):
socket = nfc.llcp.Socket(llc, nfc.llcp.LOGICAL_DATA_LINK)
Thread(target=client, args=(socket,)).start()
return True
clf = nfc.ContactlessFrontend()
clf.connect(llcp={'on-connect': connected})
Although service access points are generally identified by a numerical address, the LLCP service discovery component allows SAPs to be associated with a globally unique service name and become discoverable by remote applications. A service name may represent either an NFC Forum well-known or an externally defined service name.
- The format
urn:nfc:sn:<servicename>
represents a well-known service name, for example the service nameurn:nfc:sn:snep
identifies the NFC Forum Simple NDEF Data Exchange (SNEP) default server. - The format
urn:nfc:xsn:<domain>:<servicename>
represents a service name that is defined by the domain owner, for example the service nameurn:nfc:xsn:nfc-forum.org:snep-validation
is the service name of a special SNEP server used by the NFC Forum during validation of the SNEP secification.
In nfcpy a service name can be registered with Socket.bind()
and a service name string as the address parameter. The allocated
service access point address number can then be retrived with
getsockname()
. A remote service name can be resolved
into a service access point address number with
resolve()
.
def server(socket):
message, address = socket.recvfrom()
socket.sendto("It's me!", address)
def client(socket):
address = socket.resolve( 'urn:nfc:xsn:nfcpy.org:test-service' )
socket.sendto("Hi there!", address)
message, address = socket.recvfrom()
print("SAP {0} said: {1}".format(address, message))
def startup(clf, llc):
socket = nfc.llcp.Socket(llc, nfc.llcp.LOGICAL_DATA_LINK)
socket.bind( 'urn:nfc:xsn:nfcpy.org:test-service' )
print("server bound to SAP {0}".format(socket.getsockname()))
Thread(target=server, args=(socket,)).start()
return llc
def connected(llc):
socket = nfc.llcp.Socket(llc, nfc.llcp.LOGICAL_DATA_LINK)
Thread(target=client, args=(socket,)).start()
return True
clf = nfc.ContactlessFrontend()
clf.connect(llcp={'on-startup': startup, 'on-connect': connected})
Connection-mode sockets must be connected before data can be
exchanged. For a server socket this involves calls to
bind()
, listen()
and
accept()
, and for a client socket to call
resolve()
and connect()
with the address
returned by resolve()
or to simply call
connect()
with the service name as address (note that
resolve()
becomes more efficient when queries for
multiple service names are needed).
def server(socket):
# note that this server only accepts one connection
# for multiple connections spawn a thread per accept
while True:
client = socket.accept()
while True:
message = client.recv()
print("Client said: {0}".format(message))
client.send("It's me!")
def client(socket):
socket.connect( 'urn:nfc:xsn:nfcpy.org:test-service' )
socket.send("Hi there!")
message = socket.recv()
print("Server said: {0}".format(message))
def startup(clf, llc):
socket = nfc.llcp.Socket(llc, nfc.llcp.DATA_LINK_CONNECTION)
socket.bind( 'urn:nfc:xsn:nfcpy.org:test-service' )
print("server bound to SAP {0}".format(socket.getsockname()))
socket.listen()
Thread(target=server, args=(socket,)).start()
return llc
def connected(llc):
socket = nfc.llcp.Socket(llc, nfc.llcp.DATA_LINK_CONNECTION)
Thread(target=client, args=(socket,)).start()
return True
clf = nfc.ContactlessFrontend()
clf.connect(llcp={'on-startup': startup, 'on-connect': connected})
Data can be send and received with sendto()
and
recvfrom()
on connection-less sockets and
send()
and recv()
on connection-mode
sockets. Send data is guaranteed to be delivered to the remote device
when the send methods return (although not necessarily to the remote
service access point - only for a connection-mode socket this can be
safely assumed but note that even then data may not yet have been
arrived at the service user). Receiving data with either
recv()
or recvfrom()
blocks until some
data has become available or all LLCP communication has been
terminated (if either one peer intentionally closes the LLCP Link or
the devices are moved out of communication range). To implement a
communication timeout during normal operation, the
poll()
method can be used to waI will “fix” this bug by
adding to the documentationI will “fix” this bug by adding to the
documentationit for a ‘recv’ event with a given timeout.
def client(socket):
socket.connect( 'urn:nfc:xsn:nfcpy.org:test-service' )
socket.send("Hi there!")
if socket.poll('recv', timeout=1.0):
message = socket.recv()
print("Server said: {0}".format(message))
else:
print("Server said nothing within 1 second")
Sockets of type nfc.llcp.LOGICAL_DATA_LINK
,
DATA_LINK_CONNECTION
and RAW_ACCESS_POINT
(which
should normally not be used) do not provide fragmentation for messages
that do not fit into a single protocol data unit but raise an
nfc.llcp.Error
exception with errno.EMSGSIZE
. An
application can learn the maximum nuber of bytes for sending or
receiving by calling getsockopt()
with option
nfc.llcp.SO_SNDMIU
or nfc.llcp.SO_RCVMIU
.
send_miu = socket.getsockopt(nfc.llcp.SO_SNDMIU)
recv_miu = socket.getsockopt(nfc.llcp.SO_RCVMIU)
When opening or accepting a data link connection an application may
specify the maximum number of octets to receive with the
nfc.llcp.SO_RCVMIU
option in setsockopt()
. The
value must be between 128 and 2176, inclusively. If the RCVMIU is not
explicitely set for a data link connection the default value applied
by the peer is 128 octets.
On connection-mode sockets options nfc.llcp.SO_SNDBUF
and
nfc.llcp.SO_RCVBUF
can be used to learn the local and remote
receive window values established during connection setup. The local
receive window can also be set with setsockopt()
before
the socket gets connected.
def server(llc):
socket = nfc.llcp.Socket(llc, nfc.llcp.DATA_LINK_CONNECTION)
socket.setsockopt(nfc.llcp.SO_RCVMIU, 1000)
socket.setsockopt(nfc.llcp.SO_RCVBUF, 2)
socket.bind( "urn:nfc:sn:snep" )
socket.listen()
socket.accept()
...
def client(llc):
socket = nfc.llcp.Socket(llc, nfc.llcp.DATA_LINK_CONNECTION)
socket.setsockopt(nfc.llcp.SO_RCVMIU, 1000)
socket.setsockopt(nfc.llcp.SO_RCVBUF, 2)
socket.connect( "urn:nfc:sn:snep" )
...
LLCP data link connections use sliding window flow-control. The
receive window set with nfc.llcp.SO_RCVBUF
dictates the
number of connection-oriented information PDUs that the remote side of
the data link connection may have outstanding (sent but not
acknowledged) at any time. A connection-mode socket is able to receive
and buffer that number of packets. Whenever the service user (the
application) retrieves one or more messages from the socket, reception
of the messages will be acknowledged to the remote SAP.
A common application architecture is that messages are received in a
dedicated thread and then added to a message queue that the
application will query for data to process at a later time. Unless the
message queue can grow indefinitely it may happen that the receive
thread is unable to add more data to the queue because the application
is not consuming data for some reason. For such situations LLCP
provides a mechanism to convey a busy indication to the remote
service user. In nfcpy an application uses setsockopt()
with option nfc.llcp.SO_RCVBSY
and value True
to set
the busy state or value False
to clear the busy state. An
application can use getsockopt()
with option
nfc.llcp.SO_RCVBSSY
to learn it’s own busy state and
nfc.llcp.SO_SNDBSY
to learn the remote application’s busy
state.
Simple NDEF Exchange Protocol¶
The NFC Forum Simple NDEF Exchange Protocol (SNEP) allows two NFC devices to exchange NDEF Messages. It is implemented in many smartphones and typically used to push phonebook contacts or web page URLs to another phone.
SNEP is a stateless request/response protocol. The client sends a request to the server, the server processes that request and returns a response. On the protocol level both the request and response have no consequences for further request/response exchanges. Information units transmitted through SNEP are NDEF messages. The client may use a SNEP PUT request to send an NDEF message and a SNEP GET request to retrieve an NDEF message. The message to retrieve with a GET request depends on an NDEF message sent with the GET request but the rules to determine equivalence are an application layer contract and not specified by SNEP.
NDEF messages can easily be larger than the maximum information unit
(MIU) supported by the LLCP data link connection that a SNEP client
establishes with a SNEP server. The SNEP layer handles fragmentation
and reassembly so that an application must not be concerned. To avoid
exhaustion of the limited NFC bandwidth if an NDEF message would
exceed the SNEP receiver’s capabilities, the receiver must acknowledge
the first fragment of an NDEF message that can not be transmitted in a
single MIU. The acknowledge can be either the request/response codes
CONTINUE or REJECT. If CONTINUE is received, the SNEP sender shall
transmit all further fragments without further acknowledgement (the
LLCP data link connection guarantees successful transmission). If
REJECT isreceived, the SNEP sender shall abort
tranmsission. Fragmentation and reassembly are handled transparently
by the nfc.snep.SnepClient
and nfc.snep.SnepServer
implementation and only a REJECT would be visible to the user.
A SNEP server may return other response codes depending on the result of a request:
- A SUCCESS response indicates that the request has succeeded. For a GET request the response will include an NDEF message. For a PUT request the response is empty.
- A NOT FOUND response says that the server has not found anything matching the request. This may be a temporary of permanent situation, i.e. the same request send later could yield a different response.
- An EXCESS DATA response may be received if the server has found a matching response but sending it would exhaust the SNEP client’s receive capabilities.
- A BAD REQUEST response indicates that the server detected a syntax error in the client’s request. This should almost never be seen.
- The NOT IMPLEMENTED response will be returned if the client sent a request that the server has not implemented. It applies to existing as well as yet undefined (future) request codes. The client can learn the difference from the version field transmitted withnthe response, but in reality it doesn’t matter - it’s just not supported.
- With UNSUPPORTED VERSION the server reacts to a SNEP version number sent with the request that it doesn’t support or refuses to support. This should be seen only if the client sends with a higher major version number than the server has implemented. It could be received also if the client sends with a lower major version number but SNEP servers are likely to support historic major versions if that ever happens (the current SNEP version is 1.0).
Besides the protocol layer the SNEP specification also defines a Default SNEP Server with the well-known LLCP service access point address 4 and service name urn:nfc:sn:snep. Certified NFC Forum Devices must have the Default SNEP Server implemented. Due to that requirement the feature set and guarantees of the Default SNEP Server are quite limited - it only implements the PUT request and the NDEF message to put could be rejected if it is more than 1024 octets, though smartphones generally seem to support more.
Default Server¶
A basic Default SNEP Server can be built with nfcpy like in the following example, where all error and exception handling has been sacrified for brevity.
import nfc
import nfc.snep
class DefaultSnepServer(nfc.snep.SnepServer):
def __init__(self, llc):
nfc.snep.SnepServer.__init__(self, llc, "urn:nfc:sn:snep")
def put(self, ndef_message):
print "client has put an NDEF message"
print ndef_message.pretty()
return nfc.snep.Success
def startup(clf, llc):
global my_snep_server
my_snep_server = DefaultSnepServer(llc)
return llc
def connected(llc):
my_snep_server.start()
return True
my_snep_server = None
clf = nfc.ContactlessFrontend("usb")
clf.connect(llcp={'on-startup': startup, 'on-connect': connected})
This server will accept PUT requests with NDEF messages up to 1024
octets and return NOT IMPLEMENTED for any GET request. To increase the
size of NDEF messages that can be received, the
max_ndef_message_recv_size parameter can be passed to the
nfc.snep.SnepServer
class.
class DefaultSnepServer(nfc.snep.SnepServer):
def __init__(self, llc):
nfc.snep.SnepServer.__init__(self, llc, "urn:nfc:sn:snep", 10*1024)
Using SNEP Put¶
Sending an NDEF message to the Default SNEP Server is easily done
with an instance of nfc.snep.SnepClient
and is basically to
call nfc.snep.SnepClient.put()
with the message to send. The
example below shows how the function to send the NDEF message is
started as a separate thread - it cannot be directly called in
connected()
because the main thread context is used to run the
LLCP link.
import nfc
import nfc.snep
import threading
def send_ndef_message(llc):
sp = nfc.ndef.SmartPosterRecord('http://nfcpy.org', title='nfcpy home')
snep = nfc.snep.SnepClient(llc)
snep.put( nfc.ndef.Message(sp) )
def connected(llc):
threading.Thread(target=send_ndef_message, args=(llc,)).start()
return True
clf = nfc.ContactlessFrontend("usb")
clf.connect(llcp={'on-connect': connected})
Some phones require that a SNEP be present even if they are not going to send anything (Windows Phone 8 is such example). The solution is to also run a SNEP server on urn:nfc:sn:snep which may just do nothing.
import nfc
import nfc.snep
import threading
server = None
def send_ndef_message(llc):
sp = nfc.ndef.SmartPosterRecord('http://nfcpy.org', title='nfcpy home')
snep = nfc.snep.SnepClient(llc)
snep.put( nfc.ndef.Message(sp) )
def startup(clf, llc):
global server
server = nfc.snep.SnepServer(llc, "urn:nfc:sn:snep")
return llc
def connected(llc):
server.start()
threading.Thread(target=send_ndef_message, args=(llc,)).start()
return True
clf = nfc.ContactlessFrontend("usb")
clf.connect(llcp={'on-startup': startup, 'on-connect': connected})
Private Servers¶
The SNEP protocol can be used for other, non-standard, communication between a server and client component. A private server can be run on a dynamically assigned service access point if a private service name is used. A private server may also implement the GET request if it defines what a GET shall mean other than to return something. Below is an example of a private SNEP server that implements bot PUT and GET with the simple contract that whatever is put to the server will be returned for a GET request that requests the same or empty NDEF type and name values (for anything else the answer is NOT FOUND).
import nfc
import nfc.snep
class PrivateSnepServer(nfc.snep.SnepServer):
def __init__(self, llc):
self.ndef_message = nfc.ndef.Message(nfc.ndef.Record())
service_name = "urn:nfc:xsn:nfcpy.org:x-snep"
nfc.snep.SnepServer.__init__(self, llc, service_name, 2048)
def put(self, ndef_message):
print "client has put an NDEF message"
self.ndef_message = ndef_message
return nfc.snep.Success
def get(self, acceptable_length, ndef_message):
print "client requests an NDEF message"
if ((ndef_message.type == '' and ndef_message.name == '') or
((ndef_message.type == self.ndef_message.type) and
(ndef_message.name == self.ndef_message.name))):
if len(str(self.ndef_message)) > acceptable_length:
return nfc.snep.ExcessData
return self.ndef_message
return nfc.snep.NotFound
def startup(clf, llc):
global my_snep_server
my_snep_server = PrivateSnepServer(llc)
return llc
def connected(llc):
my_snep_server.start()
return True
my_snep_server = None
clf = nfc.ContactlessFrontend("usb")
clf.connect(llcp={'on-startup': startup, 'on-connect': connected})
A client application knowing the private server above may then use PUT
and GET to set an NDEF message on the server and retrieve it back. The
example code below also shows how results other than SUCCESS must be
catched in try-except clauses. Note that max_ndef_msg_recv_size
parameter is a policy sent to the SNEP server with every GET
request. It is a arbitrary restriction of the
nfc.snep.SnepClient
that this parameter can only be set when
the object is created; the SNEP protocol would allow it to be
different for every GET request but unless there’s demand for such
flexibility that won’t change.
import nfc
import nfc.snep
import threading
def send_ndef_message(llc):
sp = nfc.ndef.SmartPosterRecord('http://nfcpy.org', title='nfcpy home')
snep = nfc.snep.SnepClient(llc, max_ndef_msg_recv_size=2048)
snep.connect("urn:nfc:xsn:nfcpy.org:x-snep")
snep.put( nfc.ndef.Message(sp) )
print "*** get whatever the server has ***"
print snep.get().pretty()
print "*** get a smart poster with no name ***"
r = nfc.ndef.Record(record_type="urn:nfc:wkt:Sp", record_name="")
print snep.get( nfc.ndef.Message(r) ).pretty()
print "*** get something that isn't there ***"
r = nfc.ndef.Record(record_type="urn:nfc:wkt:Uri")
try:
snep.get( nfc.ndef.Message(r) )
except nfc.snep.SnepError as error:
print repr(error)
def connected(llc):
threading.Thread(target=send_ndef_message, args=(llc,)).start()
return True
clf = nfc.ContactlessFrontend("usb")
clf.connect(llcp={'on-connect': connected})
Example Programs¶
- tagtool.py
- Read or write or format tags for NDEF use.
- ndeftool.py
- Generate or inspect or reorganize NDEF data.
- beam.py
- Exchange NDEF data with a smartphone.
tagtool.py¶
The tagtool.py example program can be used to read or write NFC Forum Tags. For some tags, currently Type 3 Tags only, tagtool can also be used to format for NDEF use.
$ tagtool.py [-h|--help] [options] command
Options¶
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
--wait
¶
After reading or writing a tag wait until it is removed before returning. This option is implicit when the option
--loop
is set. Only relevant for reader/writer mode.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
Commands¶
Available commands are listed below. The default if no command is specified is to invoke tagtool.py show.
show¶
The show command prints information about a tag, including NDEF data if present.:
$ tagtool.py [options] show [-h] [-v]
-
-v
¶
Print verbose information about the tag found. The amount of additional information depends on the tag type.
dump¶
The dump command dumps tag data to the console or into a file. Data written to the console is a hexadecimal string. Data written to a file is raw bytes.
$ tagtool.py [options] dump [-h] [-o FILE]
-
-o
FILE
¶ Write data to FILE. Data format is plain bytes.
load¶
The load command writes data to a tag. Data may be plain bytes or a hex string, as generated by the dump command or with the ndeftool.
$ tagtool.py [options] load [-h] FILE
-
FILE
¶
Load NDEF data to write from FILE which must exist and be readable. The file may contain NDEF data in either raw bytes or a hexadecimal string which gets converted to bytes. If FILE is specified as a single dash
-
data is read from stdin.
format¶
The format command writes NDEF capability information for an empty NDEF memory area on NFC Forum compliant tags. The tag type must be specified. The only currently supported tag type it tt3.
$ tagtool.py [options] format [-h] {tt1,tt3} ...
format tt1¶
The format tt1 command formats the NDEF partition on a Type 1 Tag.
$ tagtool.py [options] format tt1 [-h]
format tt3¶
The format tt3 command formats the NDEF partition on a Type 3 Tag. With no additional options it does format for the maximum capacity. With further options it is possible to create any kind of weird tag formats for testing reader implementations.
$ tagtool.py [options] format tt3 [-h] [--ver STR] [--nbr INT] [--nbw INT]
[--max INT] [--rfu INT] [--wf INT]
[--rw INT] [--len INT] [--crc INT]
-
--ver
STR
¶ Type 3 Tag NDEF mapping version number, specified as a version string with minor and major number separated by a single dot character. Both major and minor version numbers must be in range
0<=N<=15
. The default value is"1.1"
.
-
--nbr
INT
¶ Type 3 Tag attribute block Nbr field value, the number of blocks that can be read at once. Must be in range
0<=INT<=255
. If this option is not specified the automatically detected value is written.
-
--nbw
INT
¶ Type 3 Tag attribute block Nbw field value, the number of blocks that can be written at once. Must be in range
0<=INT<=255
. If this option is not specified the automatically detected value is written.
-
--max
INT
¶ Type 3 Tag attribute block Nmaxb field value, which is the maximum number of blocks available for NDEF data. Must be in range
0<=INT<=255
. If this option is not specified the automatically detected value is written.
-
--rfu
INT
¶ Type 3 Tag attribute block reserved field value. Must be in range
0<=INT<=255
. The default value is 0.
-
--wf
INT
¶ Type 3 Tag attribute block WriteF field value. Must be in range
0<=INT<=255
. The default value is 0.
-
--rw
INT
¶ Type 3 Tag attribute block RW Flag field value. Must be in range
0<=INT<=255
. The default value is 1.
-
--len
INT
¶ Type 3 Tag attribute block Ln field value that specifies the actual size of the NDEF data stored. Must be in range
0<=INT<=16777215
. The default value is 0.
-
--crs
INT
¶ Type 3 Tag attribute block Checksum field value. Must be in range
0<=INT<=65535
. If this option is not specified the automatically computed checksum is written.
emulate¶
The emulate command emulates an NDEF tag if the hardware and driver support that functionality. The tag type must be specified following the optional parameters. The only currently supported tag type it tt3.
$ tagtool.py emulate [-h] [-l] [-k] [-s SIZE] [-p FILE] [FILE] {tt3} ...
-
FILE
¶
Initialize the tag with NDEF data read from FILE. If not specified the tag will be just empty.
-
-l
,
--loop
¶
Automatically restart after the tag has been released by the Initiator.
-
-k
,
--keep
¶
If the
--loop
option is set, keep the same memory content after tag relase for the next tag activation. Without the-k
option the tag memory is initialized from the command options for every activation.
-
-s
SIZE
¶ The maximum size for NDEF data. Depending on the tag type this may be rounded to the nearest multiple of the tag storage granularity.
-
-p
FILE
¶ Preserve memory content in FILE after the tag is relased by the Initiator. The file is created if it does not exist and otherwise overwritten.
emulate tt3¶
The emulate tt3 command emulates an NFC Forum Type 3 Tag.
$ tagtool.py [options] emulate [options] tt3 [-h] [--idm HEX] [--pmm HEX]
[--sys HEX] [--bitrate {212,424}]
-
--idm
HEX
¶ The Manufacture Identifier to use in the polling response. Specified as a hexadecimal string. Defaults to
03FEFFE011223344
.
-
--pmm
HEX
¶ The Manufacture Parameter to use in the polling response. Specified as a hexadecimal string. Defaults to
01E0000000FFFF00
.
-
--sys
HEX
,
--sc
HEX
¶ The system code use in the polling response if requested. Specified as a hexadecimal string. Defaults to
12FC
.
-
--bitrate
{212,424}
¶ The bitrate to listen for and respond with. Must be either 212 or 424. Defaults to 212 kbps.
ndeftool.py¶
The ndeftool intends to be a swiss army knife for working with NDEF data.
$ ndeftool.py [-h] [-v] [-d] {print,make,pack,split,cat} ...
Commands¶
print¶
The print command decodes and prints the content of an NDEF message. The message data may be in raw binary or hexadecimal string format and is read from message-file or standard input if message-file is not provided.:
$ ndeftool.py print [-h|--help] [message]
make¶
The make command allows generating specific NDEF messages. The type of message is determined by a further sub-command:
- make smartposter - creates a smartposter record
- make wificfg - creates a WiFi Configuration record
- make wifipwd - creates a WiFi Password record
- make btcfg - creates a Bluetooth out-of-band record
make smartposter¶
The make smartposter command creates a smartposter message for the uniform resource identifier reference:
$ ndeftool.py make smartposter [-h|--help] [options] reference
Options:
-
-t
titlespec
¶ Add a smart poster title. The titlespec consists of an ISO/IANA language code, a ”:” as separator, and the title string. The language code is optional and defaults to “en”. The separator may then also be omitted unless the title string itself contains a colon. Multiple
-t
options may be present for different languages.
-
-i
iconfile
¶ Add a smart poster icon. The iconfile must be an existing and readable image file for which a mime type is registered. Multiple
-i
options may be present for different image types.
-
-a
actionstring
¶ Set the smart poster action. Valid action strings are “default” (default action of the receiving device), “exec” (send SMS, launch browser, call phone number), “save” (store SMS in INBOX, bookmark hyperlink, save phone number in contacts), and “edit”.
-
-o
output-file
¶ Write message data to output-file (default is write to standard output). The
-o
option also switches the output format to raw bytes versus the hexadecimal string written to stdout.
make wificfg¶
The make wificfg command creates a configuration token for the WiFi network with SSID network-name. Without further options this command creates configuration data for an open network:
$ ndeftool.py make wificfg [-h|--help] [options] network-name
Options:
-
--key
network-key
¶ Set the network-key for a secured WiFi network. The security method is set to WPA2-Personal.
-
--mixed-mode
¶
With this option set the security method is set to also include the older WPA-Personal standard.
-
--mac
mac-address
¶ The MAC address of the device for which the credential was generated. Without the
--mac
option the broadcast MAC “ff:ff:ff:ff:ff:ff” is used to indicate that the credential is not device specific.
Set this option if the network configuration may be shared with other devices.
-
-o
output-file
¶ Write message data to output-file (default is write to standard output). The
-o
option also switches the output format to raw bytes versus the hexadecimal string written to stdout.
-
--hs
¶
Encapsulate the Wifi Configuration record into a Handover Select Message. The carrier power state will set to ‘unknown’.
-
--active
¶
Generate a Handover Select message with the WiFi carrier power state set to ‘active’. This option is mutually exclusive with the
--inactive
and--activating
options.
-
--inactive
¶
Generate a Handover Select message with the WiFi carrier power state set to ‘inactive’. This option is mutually exclusive with the
--active
and--activating
options.
-
--activating
¶
Generate a Handover Select message with the WiFi carrier power state set to ‘activating’. This option is mutually exclusive with the
--active
and--inactive
options.
make wifipwd¶
The make wifipwd command creates a password token for the WiFi Protected Setup registration protocol, signed with the first 160 bits of SHA-256 hash of the enrollee’s public key in public-key-file.:
$ ndeftool.py make wificfg [-h|--help] [options] public-key-file
Options:
-
-p
device-password
¶ A 16 - 32 octet long device password. If the
-p
option is not given a 32 octet long random device password is generated.
-
-i
password-id
¶ An arbitrary value between 0x0010 and 0xFFFF that serves as an identifier for the device password. If the
-i
option is not given a random password identifier is generated.
-
-o
output-file
¶ Write message data to output-file (default is write to standard output). The
-o
option also switches the output format to raw bytes versus the hexadecimal string written to stdout.
make btcfg¶
The make btcfg command creates an out-of-band configuration record for a Bluetooth device.:
$ ndeftool.py make btcfg [-h|--help] [options] device-address
Options:
-
-c
class-of-device
¶ The 24 class of device/service bits as a string of ‘0’ and ‘1’ characters, with the most significant bit left.
-
-n
name-of-device
¶ The user friendly name of the device.
-
-s
service-class
¶ A service class implemented by the device. A service class may be specified by description or as a 128-bit UUID string (for example, “00001108-0000-1000-8000-00805f9b34fb” would indicate “Printing”). Textual descriptions are evaluated case insensitive and must then match one of the following:
‘Handsfree Audio Gateway’, ‘PnP Information’, ‘Message Access Server’, ‘ESDP UPNP IP PAN’, ‘HDP Source’, ‘Generic Networking’, ‘Message Notification Server’, ‘Browse Group Descriptor’, ‘NAP’, ‘A/V Remote Control Target’, ‘Basic Imaging Profile’, ‘Generic File Transfer’, ‘Message Access Profile’, ‘Generic Telephony’, ‘Basic Printing’, ‘Intercom’, ‘HCR Print’, ‘Dialup Networking’, ‘Advanced Audio Distribution’, ‘Printing Status’, ‘OBEX File Transfer’, ‘Handsfree’, ‘Hardcopy Cable Replacement’, ‘Imaging Responder’, ‘Phonebook Access - PSE’, ‘ESDP UPNP IP LAP’, ‘IrMC Sync’, ‘Cordless Telephony’, ‘LAN Access Using PPP’, ‘OBEX Object Push’, ‘Video Source’, ‘Audio Source’, ‘Human Interface Device’, ‘Video Sink’, ‘Reflected UI’, ‘ESDP UPNP L2CAP’, ‘Service Discovery Server’, ‘HDP Sink’, ‘Direct Printing Reference’, ‘Serial Port’, ‘SIM Access’, ‘Imaging Referenced Objects’, ‘UPNP Service’, ‘A/V Remote Control Controller’, ‘HCR Scan’, ‘Headset - HS’, ‘UPNP IP Service’, ‘IrMC Sync Command’, ‘GNSS’, ‘Headset’, ‘WAP Client’, ‘Imaging Automatic Archive’, ‘Phonebook Access’, ‘Fax’, ‘Generic Audio’, ‘Audio Sink’, ‘GNSS Server’, ‘A/V Remote Control’, ‘Video Distribution’, ‘WAP’, ‘Common ISDN Access’, ‘Direct Printing’, ‘GN’, ‘PANU’, ‘Phonebook Access - PCE’, ‘Headset - Audio Gateway (AG)’, ‘Reference Printing’, ‘HDP’
-
-o
output-file
¶ Write message data to output-file (default is write to standard output). The
-o
option also switches the output format to raw bytes versus the hexadecimal string written to stdout.
-
--hs
¶
Encapsulate the Bluetooth Configuration record into a Handover Select Message. The carrier power state will set to ‘unknown’ unless one of the options –active, –inactive or –activating is given.
-
--active
¶
Generate a Handover Select message with the Bluetooth carrier power state set to ‘active’. This option is mutually exclusive with the
--inactive
and--activating
options.
-
--inactive
¶
Generate a Handover Select message with the Bluetooth carrier power state set to ‘inactive’. This option is mutually exclusive with the
--active
and--activating
options.
-
--activating
¶
Generate a Handover Select message with the Bluetooth carrier power state set to ‘activating’. This option is mutually exclusive with the
--active
and--inactive
options.
pack¶
The pack command converts a file into an NDEF record with both
message begin and end flag set to 1. If the -t
option is not given
the record type is guessed from the file content using the mimetypes
module. The record name is by default set to the name of the file
being converted, unless data is read from stdin in which case the
record name is not encoded.
If a file mime type is text/plain
it will be encoded as an NDEF
Text Record (type urn:nfc:wkt:T
) if -t
is not set. The text
record language is guessed from the file content if the Python module
guess_language
is installed, otherwise set to English.
$ ndeftool.py pack [-h|--help] [options] FILE
Options:
-
-t
record-type
¶ Set the record type to record-type (the default is to guess it from the file mime type).
-
-n
record-name
¶ Set the record identifier to record-name (the default is to use the file path name).
-
-o
output-file
¶ Write message data to output-file (default is write to standard output). The
-o
option also switches the output format to raw bytes versus the hexadecimal string written to stdout.
split¶
The split command separates an an NDEF message into individual records. If data is read from a file, records are written as binary data into individual files with file names constructed from the input file base name, a hyphen followed by a three digit number and the input file name extension. If data is read from stdin, records are written to stdout as individual lines of hexadecimal strings.
$ ndeftool.py split [-h|--help] [options] message-file
Options:
-
--keep-message-flags
¶
Do not reset the record’s message begin and end flags but leave tem as found in the input message data.
cat¶
The cat command concatenates records into a single message.
$ ndeftool.py cat [-h|--help] record-file [record-file ...]
Options:
-
-o
output-file
¶ Write message data to output-file (default is write to standard output). The
-o
option also switches the output format to raw bytes versus the hexadecimal string written to stdout.
Examples¶
To build a smartposter that points to the nfcpy documentation page:
$ ndeftool.py make smartposter http://nfcpy.org/docs
d102135370d1010f55036e666370792e6f72672f646f6373
The output can be made readable with the ndeftool print command:
$ ndeftool.py make smartposter http://nfcpy.org/docs | ndeftool.py print
Smartposter Record
resource = http://nfcpy.org/docs
action = default
To get the smartposter as raw bytes specify an output file:
$ ndeftool.py make smartposter http://nfcpy.org/docs -o sp_nfcpy_docs.ndef
Here’s a more complex example setting multi-language smartposter title, icons and a non-default action:
$ ndeftool.py make smartposter http://nfcpy.org/docs -t "nfcpy documentation" -t "de:nfcpy Dokumentation" -i logo.gif -i logo.png -a save -o sp_nfcpy_docs.ndef
It is sometimes helpful to have an NDEF message of specific length where the payload consists of monotonically increasing byte values:
$ python -c "import sys; sys.stdout.write(bytearray([x % 256 for x in xrange(1024-6)]))" | ndeftool.py pack - -o message-1k.ndef
beam.py¶
The beam.py example program uses the Simple NDEF Exchange Protocol (SNEP) to send or receive NDEF messages to or from a peer device, in most cases this will be a smartphone. The name beam is inspired by Android Beam and thus beam.py will be able to receive most content sent through Android Beam. It will not work for data that Android Beam sends with connection handover to Bluetooth or Wi-Fi, this may become a feature in a later version. Despite it’s name, beam.py works not only with Android phones but any NFC enabled phone that implements the NFC Forum Default SNEP Server, such as Blackberry and Windows Phone 8.
$ beam.py [-h|--help] [OPTIONS] {send|recv} [-h] [OPTIONS]
Options¶
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
--mode
{t,i}
¶ Restrict the choice of NFC-DEP connection setup role to either
Target
(only listen) orInitiator
(only poll). If this option is not given the dafault is to alternate between both roles with a randomized listen time.
-
--miu
INT
¶ Set a specific value for the LLCP Link MIU. The dafault value is 2175 octets.
-
--lto
INT
¶ Set a specific LLCP Link Timeout value. The default link timeout is 500 milliseconds.
-
--listen-time
INT
¶ Set the time to listen for initialization command from an NFC-DEP Initiator. The default listen time is 250 milliseconds.
-
--no-aggregation
¶
Disable outbound packet aggregation for LLCP, i.e. do not generate LLCP AGF PDUs if multiple packets are waiting to be send. This is mostly to achieve communication with some older/buggy implementations.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
Commands¶
send¶
Send an NDEF message to the peer device. The message depends on the positional argument that follows the send command and additional data.
$ beam.py send [--timeit] {link,text,file,ndef} [-h] [OPTIONS]
-
--timeit
¶
Measure and print the time that was needed to send the message.
send link¶
Send a hyperlink embedded into a smartposter record.
$ beam.py send link URI [TITLE]
-
URI
¶
The resource identifier, for example
http://nfcpy.org
.
-
TITLE
¶
The smartposter title, for example
"nfcpy project home"
.
send text¶
Send plain text embedded into an NDEF Text Record. The default
language identifier en
can be changed with the --lang
flag.
$ beam.py send text TEXT [OPTIONS]
-
TEXT
¶
The text string to send.
-
--lang
STRING
¶ The language code to use when constructing the NDEF Text Record.
send file¶
Send a data file. This will construct a single NDEF record with type
and name set to the file’s mime type and path name, and the payload
containing the file content. Both record type and name can also be
explicitly set with the options -t
and -n
, respectively.
$ beam.py send file FILE [OPTIONS]
-
FILE
¶
The file to send.
-
-t
STRING
¶ Set the record type. See NFC Data Exchange Format for how to specify record types in nfcpy.
-
-n
STRING
¶ Set the record name (identifier).
send ndef¶
Send an NDEF message read from file. The file may contain multiple
messages and if it does, then the strategy to select a specific
message for sending can be specified with the --select STRATEGY
option. For strategies that select a different message per touch
beam.py must be called with the --loop
flag. The strategies
first
, last
and random
select the first, or last, or a
random message from FILE. The strategies next
and cycle
start
with the first message and then count up, the difference is that
next
stops at the last message while cycle
continues with the
first.
$ beam.py send ndef FILE [OPTIONS]
-
FILE
¶
The file from which to read NDEF messages.
-
--select
STRATEGY
¶ The strategy for NDEF message selection, it may be one of
first
,last
,next
,cycle
,random
.
recv¶
Receive an NDEF message from the peer device. The next positional argument determines what is done with the received message.
$ beam.py [OPTIONS] recv {print,save,echo,send} [-h] [OPTIONS]
recv save¶
Save the received message into a file. If the file already exists the message is appended.
$ beam.py recv save FILE
-
FILE
¶
Name of the file to save messages received from the remote peer. If the file exists any new messages are appended.
recv send¶
Receive a message and send back a corresponding message if such is found in the translations file. The translations file must contain an even number of NDEF messages which are sequentially read into inbound/outbound pairs to form a translation table. If the receved message corresponds to any of the translation table inbound messages the corresponding outbound message is then sent back.
$ beam.py [OPTIONS] recv send [-h] TRANSLATIONS
-
TRANSLATIONS
¶
A file with a sequence of NDEF messages.
Examples¶
Get a smartphone to open the nfcpy project page (which in fact just points to the code repository and documentation).
$ beam.py send link http://nfcpy.org "nfcpy project home"
Send the source file beam.py
. On an Android phone this should pop
up the “new tag collected” screen and show that a text/x-python
media type has been received.
$ beam.py send file beam.py
The file beam.py
is about 11 KB and may take some time to
transfer, depending on the phone hardware and software. With a Google
Nexus 10 it takes as little as 500 milliseconds while a Nexus 4 won’t
do it under 2.5 seconds.
$ beam.py send --timeit file beam.py
Receive a single NDEF message from the peer device and save it to message.ndef (note that if message.ndef exists the received data will be appended):
$ beam.py recv save message.ndef
With the --loop
option it gets easy to collect messages into
a single file.
$ beam.py --loop recv save collected.ndef
A file that contains a sequence of request/response message pairs can be used to send a specific response message whenever the associated request message was received.
$ echo -n "this is a request message" > request.txt
$ ndeftool.py pack -n '' request.txt -o request.ndef
$ echo -n "this is my reponse message" > response.txt
$ ndeftool.py pack -n '' response.txt -o response.ndef
$ cat request.ndef response.ndef > translation.ndef
$ beam.py recv send translation.ndef
Interoperability Tests¶
Logical Link Control Protocol¶
llcp-test-server.py¶
The LLCP test server program implements an NFC device that provides three distinct server applications:
A connection-less echo server that accepts connection-less transport mode PDUs. Service data units may have any size between zero and the maximum information unit size announced with the LLCP Link MIU parameter. Inbound service data units enter a linear buffer of service data units. The buffer has a capacity of two service data units. The first service data unit entering the buffer starts a delay timer of 2 seconds (echo delay). Expiration of the delay timer causes service data units in the buffer to be sent back to the original sender, which may be different for each service data unit, until the buffer is completely emptied. The buffer empty condition then re-enables the delay timer start event for the next service data unit.
A connection-mode echo server that waits for a connect request and then accepts and processes connection-oriented transport mode PDUs. Further connect requests will be rejected until termination of the data link connection. When accepting the connect request, the receive window parameter is transmitted with a value of 2.
The connection-oriented mode echo service stores inbound service data units in a linear buffer of service data units. The buffer has a capacity of three service data units. The first service data unit entering the buffer starts a delay timer of 2 seconds (echo delay). Expiration of the delay timer causes service data units in the buffer to be sent back to the orignal sender until the buffer is completely emptied. The buffer empty condition then re-enables the delay timer start event for the next service data unit.
The echo service determines itself as busy if it is unable to accept further incoming service data units.
A connection-mode dump server that accepts connections and then accepts and forgets all data received on a data link connection. This is mostly useful to measure transfer speed under load conditions.
Usage
$ llcp-test-server.py [-h|--help] [OPTION]...
Options
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
--mode
{t,i}
¶ Restrict the choice of NFC-DEP connection setup role to either
Target
(only listen) orInitiator
(only poll). If this option is not given the dafault is to alternate between both roles with a randomized listen time.
-
--miu
INT
¶ Set a specific value for the LLCP Link MIU. The dafault value is 2175 octets.
-
--lto
INT
¶ Set a specific LLCP Link Timeout value. The default link timeout is 500 milliseconds.
-
--listen-time
INT
¶ Set the time to listen for initialization command from an NFC-DEP Initiator. The default listen time is 250 milliseconds.
-
--no-aggregation
¶
Disable outbound packet aggregation for LLCP, i.e. do not generate LLCP AGF PDUs if multiple packets are waiting to be send. This is mostly to achieve communication with some older/buggy implementations.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
llcp-test-client.py¶
Usage
$ llcp-test-client.py [-h|--help] [OPTION]...
Options
-
-t
N
,
--test
N
¶ Run test number N. May be set more than once.
-
-T
,
--test-all
¶
Run all tests.
-
--cl-echo
SAP
¶ Service access point address of the connection-less mode echo server.
-
--co-echo
SAP
¶ Service access point address of the connection-oriented mode echo server.
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
--mode
{t,i}
¶ Restrict the choice of NFC-DEP connection setup role to either
Target
(only listen) orInitiator
(only poll). If this option is not given the dafault is to alternate between both roles with a randomized listen time.
-
--miu
INT
¶ Set a specific value for the LLCP Link MIU. The dafault value is 2175 octets.
-
--lto
INT
¶ Set a specific LLCP Link Timeout value. The default link timeout is 500 milliseconds.
-
--listen-time
INT
¶ Set the time to listen for initialization command from an NFC-DEP Initiator. The default listen time is 250 milliseconds.
-
--no-aggregation
¶
Disable outbound packet aggregation for LLCP, i.e. do not generate LLCP AGF PDUs if multiple packets are waiting to be send. This is mostly to achieve communication with some older/buggy implementations.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
Test Scenarios¶
Link activation, symmetry and deactivation¶
$ llcp-test-client.py -t 1
Verify that the LLCP Link can be activated successfully, that the symmetry procedure is performed and the link can be intentionally deactivated.
- Start the MAC link activation procedure on two implementations and verify that the version number parameter is received and version number agreement is achieved.
- Verify for a duration of 5 seconds that SYMM PDUs are exchanged within the Link Timout values provided by the implementations.
- Perform intentional link deactivation by sending a DISC PDU to the remote Link Management component. Verify that SYMM PDUs are no longer exchanged.
Connection-less information transfer¶
$ llcp-test-client.py -t 2
Verify that the source and destination access point address fields are correctly interpreted, the content of the information field is extracted as the service data unit and the service data unit can take any length between zero and the announced Link MIU. The LLCP Link must be activated prior to running this scenario and the Link MIU of the peer implementation must have been determined. In this scenario, sending of a service data unit (SDU) means that the SDU is carried within the information field of a UI PDU.
- Send a service data unit of 128 octets length to the connection-less mode echo service and verify that the same SDU is sent back after the echo delay time.
- Send within echo delay time with a time interval of at least 0.5 second two consecutive service data units of 128 octets length to the connection-less mode echo service and verify that both SDUs are sent back correctly.
- Send within echo delay time with a time interval of at least 0.5 second three consecutive service data units of 128 octets length to the connection-less mode echo service and verify that the first two SDUs are sent back correctly and the third SDU is discarded.
- Send a service data unit of zero octets length to the connection-less mode echo service and verify that the same zero length SDU is sent back after the echo delay time.
- Send a service data unit of maximum octets length to the connection-less mode echo service and verify that the same SDU is sent back after the echo delay time. Note that the maximum length here must be the smaller value of both implementations Link MIU.
Connection-oriented information transfer¶
$ llcp-test-client.py -t 3
Verify that a data link connection can be established, a service data unit is received and sent back correctly and the data link connection can be terminated. The LLCP Link must be activated prior to running this scenario and the connection-oriented mode echo service must be in the unconnected state. In this scenario, sending of a service data unit (SDU) means that the SDU is carried within the information field of an I PDU.
- Send a CONNECT PDU to the connection-oriented mode echo service and verify that the connection request is acknowledged with a CC PDU. The CONNECT PDU shall encode the RW parameter with a value of 2. Verify that the CC PDU encodes the RW parameter with a value of 2 (as specified for the echo server).
- Send a single service data unit of 128 octets length over the data link connection and verify that the echo service sends an RR PDU before returning the same SDU after the echo delay time.
- Send a DISC PDU to terminate the data link connection and verify that the echo service responds with a correct DM PDU.
Send and receive sequence number handling¶
$ llcp-test-client.py -t 4
Verify that a sequence of service data units that causes the send and receive sequence numbers to take all possible values is received and sent back correctly. The LLCP Link must be activated prior to running this scenario and the connection-oriented mode echo service must be in the unconnected state. In this scenario, sending of a service data unit (SDU) means that the SDU is carried within the information field of an I PDU.
- Send a CONNECT PDU to the connection-oriented mode echo service and verify that the connection request is acknowledged with a CC PDU. The CONNECT PDU shall encode the RW parameter with a value of 2. Verify that the CC PDU encodes the RW parameter with a value of 2 (as specified for the echo server).
- Send a sequence of at least 16 data units of each 128 octets length over the data link connection and verify that all SDUs are sent back correctly.
- Send a DISC PDU to terminate the data link connection and verify that the echo service responds with a correct DM PDU.
Handling of receiver busy condition¶
$ llcp-test-client.py -t 5
Verify the handling of a busy condition. The LLCP Link must be activated prior to running this scenario and the connection-oriented mode echo service must be in the unconnected state. In this scenario, sending of a service data unit (SDU) shall mean that the SDU is carried within the information field of an I PDU.
- Send a CONNECT PDU to the connection-oriented mode echo service and verify that the connect request is acknowledged with a CC PDU. The CONNECT PDU shall encode the RW parameter with a value of 0. Verify that the CC PDU encodes the RW parameter with a value of 2 (as specified for the echo server).
- Send four service data units of 128 octets length over the data link connection and verify that the echo service enters the busy state when acknowledging the last packet.
- Send a DISC PDU to terminate the data link connection and verify that the echo service responds with a correct DM PDU.
Rejection of connect request¶
$ llcp-test-client.py -t 6
Verify that an attempt to establish a second connection with the connection-oriented mode echo service is rejected. The LLCP Link must be activated prior to running this scenario.
- Send a first CONNECT PDU to the connection-oriented mode echo service and verify that the connect request is acknowledged with a CC PDU.
- Send a second CONNECT PDU to the connection-oriented mode echo service and verify that the connect request is rejected with a DM PDU and appropriate reason code.
- Send a service data unit of 128 octets length over the data link connection and verify that the echo service returns the same SDU after the echo delay time.
- Send a DISC PDU to terminate the data link connection and verify that the echo service responds with a correct DM PDU.
Connect by service name¶
$ llcp-test-client.py -t 7
Verify that a data link connection can be established by specifying a service name. The LLCP Link must be activated prior to running this scenario and the connection-oriented mode echo service must be in the unconnected state.
- Send a CONNECT PDU with an SN parameter that encodes the value “urn:nfc:sn:co-echo” to the service discovery service access point address and verify that the connect request is acknowledged with a CC PDU.
- Send a service data unit over the data link connection and verify that it is sent back correctly.
- Send a DISC PDU to terminate the data link connection and verify that the echo service responds with a correct DM PDU.
Aggregation and disaggregation¶
$ llcp-test-client.py -t 8
Verify that the aggregation procedure is performed correctly. The LLCP Link must be activated prior to running this scenario. In this scenario, sending of a service data unit (SDU) shall mean that the SDU is carried within the information field of a UI PDU.
- Send two service data units of 50 octets length to the connection-less mode echo service such that the two resulting UI PDUs will be aggregated into a single AGF PDU by the LLC sublayer. Verify that both SDUs are sent back correctly and in the same order.
- Send three service data units of 50 octets length to the connection-less mode echo service such that the three resulting UI PDUs will be aggregated into a single AGF PDU by the LLC sublayer. Verify that the two first SDUs are sent back correctly and the third SDU is discarded.
Service name lookup¶
$ llcp-test-client.py -t 9
Verify that a service name is correctly resolved into a service access point address by the remote LLC. The LLCP Link must be activated prior to running this scenario. In this scenario, sending of a service data unit (SDU) shall mean that the SDU is carried within the information field of a UI PDU.
- Send an SNL PDU with an SDREQ parameter in the information field that encodes the value “urn:nfc:sn:sdp” to the service discovery service access point address and verify that the request is responded with an SNL PDU that contains an SDRES parameter with the SAP value ‘1’ and a TID value that is the same as the value encoded in the antecedently transmitted SDREQ parameter.
- Send an SNL PDU with an SDREQ parameter in the information field that encodes the value “urn:nfc:sn:cl-echo” to the service discovery service access point address and verify that the request is responded with an SNL PDU that contains an SDRES parameter with a SAP value other than ‘0’ and a TID value that is the same as the value encoded in the antecedently transmitted SDREQ parameter.
- Send a service data unit of 128 octets length to the service access point address received in step 2 and verify that the same SDU is sent back after the echo delay time.
- Send an SNL PDU with an SDREQ parameter in the information field that encodes the value “urn:nfc:sn:sdp-test” to the service discovery service access point address and verify that the request is responded with an SNL PDU that contains an SDRES parameter with the SAP value ‘0’ and a TID value that is the same as the value encoded in the antecedently transmitted SDREQ parameter.
Send more data than allowed¶
$ llcp-test-client.py -t 10
Use invalid send sequence number¶
$ llcp-test-client.py -t 11
Use maximum data size on data link connection¶
$ llcp-test-client.py -t 12
Connect, release and connect again¶
$ llcp-test-client.py -t 13
Connect to unknown service name¶
$ llcp-test-client.py -t 14
Verify that a data link connection can be established by specifying a service name. The LLCP Link must be activated prior to running this scenario and the connection-oriented mode echo service must be in the unconnected state.
- Send a CONNECT PDU with an SN parameter that encodes the value “urn:nfc:sn:co-echo-unknown” to the service discovery service access point address and verify that the connect request is rejected.
Simple NDEF Exchange Protocol¶
snep-test-server.py¶
The SNEP test server program implements an NFC device that provides two SNEP servers:
A Default SNEP Server that is compliant with the NFC Forum Default SNEP Server defined in section 6 of the SNEP specification.
A Validation SNEP Server that accepts SNEP Put and Get requests. A Put request causes the server to store the NDEF message transmitted with the request. A Get request causes the server to attempt to return a previously stored NDEF message of the same NDEF message type and identifier as transmitted with the request. The server will keep any number of distinct NDEF messages received with Put request until the client terminates the data link connection.
The Validation SNEP Server uses the service name
urn:nfc:xsn:nfc-forum.org:snep-validation
, assigned for the purpose of validating the SNEP candidate specification prior to adoption.
Usage
$ snep-test-server.py [-h|--help] [OPTION]...
Options
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
--mode
{t,i}
¶ Restrict the choice of NFC-DEP connection setup role to either
Target
(only listen) orInitiator
(only poll). If this option is not given the dafault is to alternate between both roles with a randomized listen time.
-
--miu
INT
¶ Set a specific value for the LLCP Link MIU. The dafault value is 2175 octets.
-
--lto
INT
¶ Set a specific LLCP Link Timeout value. The default link timeout is 500 milliseconds.
-
--listen-time
INT
¶ Set the time to listen for initialization command from an NFC-DEP Initiator. The default listen time is 250 milliseconds.
-
--no-aggregation
¶
Disable outbound packet aggregation for LLCP, i.e. do not generate LLCP AGF PDUs if multiple packets are waiting to be send. This is mostly to achieve communication with some older/buggy implementations.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
snep-test-client.py¶
Usage
$ snep-test-client.py [-h|--help] [OPTION]...
Options
-
-t
N
,
--test
N
¶ Run test number N. May be set more than once.
-
-T
,
--test-all
¶
Run all tests.
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
--mode
{t,i}
¶ Restrict the choice of NFC-DEP connection setup role to either
Target
(only listen) orInitiator
(only poll). If this option is not given the dafault is to alternate between both roles with a randomized listen time.
-
--miu
INT
¶ Set a specific value for the LLCP Link MIU. The dafault value is 2175 octets.
-
--lto
INT
¶ Set a specific LLCP Link Timeout value. The default link timeout is 500 milliseconds.
-
--listen-time
INT
¶ Set the time to listen for initialization command from an NFC-DEP Initiator. The default listen time is 250 milliseconds.
-
--no-aggregation
¶
Disable outbound packet aggregation for LLCP, i.e. do not generate LLCP AGF PDUs if multiple packets are waiting to be send. This is mostly to achieve communication with some older/buggy implementations.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
Test Scenarios¶
Connect and terminate¶
$ snep-test-client.py -t 1
Verify that a data link connection with the remote validation server can be established and terminated gracefully and that the server returns to a connectable state.
- Establish a data link connection with the Validation Server.
- Verify that the data link connection was established successfully.
- Close the data link connection with the Validation Server.
- Establish a new data link connection with the Validation Server.
- Verify that the data link connection was established successfully.
- Close the data link connection with the Validation Server.
Unfragmented message exchange¶
$ snep-test-client.py -t 2
Verify that the remote validation server is able to receive unfragmented SNEP messages.
- Establish a data link connection with the Validation Server.
- Send a Put request with an NDEF message of no more than 122 octets total length.
- Verify that the Validation Server accepted the Put request.
- Send a Get request that identifies the NDEF message sent in step 2 to be retrieved.
- Verify that the retrieved NDEF message is identical to the one transmitted in step 2.
- Close the data link connection.
Fragmented message exchange¶
$ snep-test-client.py -t 3
Verify that the remote validation server is able to receive fragmented SNEP messages.
- Establish a data link connection with the Validation Server.
- Send a Put request with an NDEF message of more than 2170 octets total length.
- Verify that the Validation Server accepted the Put request.
- Send a Get request that identifies the NDEF message sent in step 2 to be retrieved.
- Verify that the retrieved NDEF message is identical to the one transmitted in step 2.
- Close the data link connection.
Multiple ndef messages¶
$ snep-test-client.py -t 4
Verify that the remote validation server accepts more than a single NDEF message on the same data link connection.
- Establish a data link connection with the Validation Server.
- Send a Put request with an NDEF message that differs from the NDEF message to be send in step 3.
- Send a Put request with an NDEF message that differs from the NDEF message that has been send send in step 2.
- Send a Get request that identifies the NDEF message sent in step 2 to be retrieved.
- Send a Get request that identifies the NDEF message sent in step 3 to be retrieved.
- Verify that the retrieved NDEF messages are identical to the NDEF messages transmitted in steps 2 and 3.
- Close the data link connection.
Undeliverable resource¶
$ snep-test-client.py -t 5
Verify verify that the remote validation server responds appropriately if the client requests an NDEF message that exceeds the maximum acceptable length specified by the request.
- Establish a data link connection with the Validation Server.
- Send a Put request with an NDEF message of total lenght N.
- Verify that the Validation Server accepted the Put request.
- Send a Get request with the maximum acceptable lenght field set to N − 1 and an NDEF message that identifies the NDEF message sent in step 2 to be retrieved.
- Verify that the server replies with the appropriate response message.
- Close the data link connection.
Default server limits¶
$ snep-test-client.py -t 7
Verify verify that the remote default server accepts a Put request with an information field of up to 1024 octets, and that it rejects a Get request.
- Establish a data link connection with the Default Server.
- Send a Put request with an NDEF message of up to 1024 octets total length.
- Verify that the Default Server replies with a Success response message.
- Send a Get request with an NDEF message of arbitrary type and identifier.
- Verify that the Default Server replies with a Not Implemented response message.
- Close the data link connection.
Connection Handover¶
The handover-test-server.py and handover-test-client.py programs provide a test facility for the NFC Forum Connection Handover 1.2 specification.
handover-test-server.py¶
Usage:
$ handover-test-server.py [-h|--help] [OPTION]... [CARRIER]...
The handover test server implements the handover selector role. A
handover client can connect to the server with the well-known service
name urn:nfc:sn:handover
and send handover request messages. The
server replies with handover select messages populated with carriers
provided through CARRIER arguments and matching the a carrier in the
received handover request carrier list.
Each CARRIER argument must provide an NDEF message file, which may be a handover select message with one or more alternative carriers (including auxiliary data) or an alternative carrier record optionally followed by one or more auxiliary data records. Note that only the handover select message format allows to specify the carrier power state. All carriers including power state information and auxiliary data records are accumulated into a list of selectable carriers, ordered by argument position and carrier sequence within a handover select message.
Unless the --skip-local
option is given, the server attempts to
include carriers that are locally available on the host device. Local
carriers are always added after all CARRIER arguments.
Note
Local carrier detection currently requires a Linux OS with the bluez Bluetooth stack and D-Bus. This is true for many Linux distributions, but has so far only be tested on Ubuntu.
Options:
-
--skip-local
¶
Skip the local carrier detection. Without this option the handover test server tries to discover locally available carriers and consider them in the selection process. Local carriers are considered after all carriers provided manually.
-
--select
NUM
¶ Return at most NUM carriers with the handover select message. The default is to return all matching carriers.
-
--delay
INT
¶ Delay the handover response for the number of milliseconds specified as INT. The handover specification says that the server should answer within 1 second and if it doesn’t the client may assume a processing error.
-
--recv-miu
INT
¶ Set the maximum information unit size for inbound LLCP packets on the data link connection between the server and the remote client. This value is transmitted with the CC PDU to the remote client.
-
--recv-buf
INT
¶ Set the receive window size for inbound LLCP packets on the data link connection between the server and the remote client. This value is transmitted with the CC PDU to the remote client.
-
--quirks
¶
This option causes the handover test server to try support non-compliant implementations if possible and as known. Currently implemented work-arounds are:
- a ‘urn:nfc:sn:snep‘ server is enabled and accepts the GET request with a handover request message that was implemented in Android Jelly Bean
- the version of the handover request message sent by Android Jelly Bean is changed to 1.1 to accomodate the missing collision resolution record that is required for version 1.2.
- the incorrect type-name-format encoding in handover carrier records sent by some Sony Xperia phones is corrected to mime-type.
Test Scenarios¶
Empty handover select response¶
$ handover-test-server.py --select 0
Verify that the remote handover client accepts a handover select message that has no alternative carriers.
A carrier that is being activated¶
$ ndeftool.py make btcfg 01:02:03:04:05:06 --activating | handover-test-server --skip-local -
Verify that the remote handover client understands and tries to connect to a Bluetooth carrier that is in the process of activation.
Delayed handover select response¶
$ examples/handover-test-server.py --delay 10000
Check hot the remote handover implementation behaves if the handover select response is delayed for about 10 seconds. This test intends to help identify user interface issues.
handover-test-client.py¶
Usage
$ handover-test-client.py [-h|--help] [OPTION]... [CARRIER]...
The handover test client implements the handover requester role. The
handover client connects to the remote server with well-known service
name urn:nfc:sn:handover
and sends handover request messages
populated with carriers provided through one or more CARRIER
arguments or implicitly if tests from the test suite are executed. The
client expects the server to reply with handover select messages that
list carriers matching one or more of the carriers sent with the
handover request carrier list.
Each CARRIER argument must provide an NDEF message file which may be a handover message with one or more alternative carriers (including auxiliary data) or an alternative carrier record followed by zero or more auxiliary data records. Note that only the handover message format allows to specify the carrier power state. All carriers, including power state information and auxiliary data records, are accumulated into a list of requestable carriers ordered by argument position and carrier sequence within a handover message.
Options
-
-t
N
,
--test
N
¶ Run test number N from the test suite. Multiple tests can be specified.
-
--relax
¶
The
--relax
option affects how missing optional, but highly recommended, handover data is handled when running test scenarios. Without--relax
any missing data is regarded as a test error that terminates test execution. With the--relax
option set only a warning message is logged.
-
--recv-miu
INT
¶ Set the maximum information unit size for inbound LLCP packets on the data link connection between the client and the remote server. This value is transmitted with the CONNECT PDU to the remote server.
-
--recv-buf
INT
¶ Set the receive window size for inbound LLCP packets on the data link connection between the client and the remote server. This value is transmitted with the CONNECT PDU to the remote server.
-
--quirks
¶
This option causes the handover test client to try support non-compliant implementations as much as possible, including and beyond the
--relax
behavor. The modifications activated with--quirks
are:- After test procedures are completed the client does not terminate the LLCP link but waits until the link is disrupted to prevent the NFC stack segfault and recovery on pre 4.1 Android devices.
- Try sending the handover request message with a SNEP GET request to the remote default SNEP server if the urn:nfc:sn:handover service is not available.
Test Scenarios¶
Presence and connectivity¶
$ handover-test-client.py -t 1
Verify that the remote device has the connection handover service active and that the client can open, close and re-open a connection with the server.
- Connect to the remote handover service.
- Close the data link conection.
- Connect to the remote handover service.
- Close the data link conection.
Empty carrier list¶
$ handover-test-client.py -t 2
Verify that the handover server responds to a handover request without alternative carriers with a handover select message that also has no alternative carriers.
- Connect to the remote handover service.
- Send a handover request message containing zero alternative carriers.
- Verify that the server returns a handover select message within no more than 3 seconds; and that the message contains zero alternative carriers.
- Close the data link conection.
Version handling¶
$ handover-test-client.py -t 3
Verify that the remote handover server handles historic and future
handover request version numbers. This test is run as a series of
steps where for each step the connection to the server is established
and closed after completion. For all steps the configuration sent is a
Bluetooth carrier for device address 01:02:03:04:05:06
.
- Connect to the remote handover service.
- Send a handover request message with version
1.2
. - Verify that the server replies with version
1.2
. - Close the data link conection.
- Connect to the remote handover service.
- Send a handover request message with version
1.1
. - Verify that the server replies with version
1.2
. - Close the data link conection.
- Connect to the remote handover service.
- Send a handover request message with version
1.15
. - Verify that the server replies with version
1.2
. - Close the data link conection.
- Connect to the remote handover service.
- Send a handover request message with version
15.0
. - Verify that the server replies with version
1.2
. - Close the data link conection.
Bluetooth just-works pairing¶
$ handover-test-client.py -t 4
Verify that the application/vnd.bluetooth.ep.oob
alternative
carrier is correctly evaluated and replied. This test is only
applicable if the peer device does have Bluetooth connectivity.
- Connect to the remote handover service.
- Send a handover request message with a single alternative carrier
of type
application/vnd.bluetooth.ep.oob
and power stateactive
. Secure pairing hash and randomizer are not provided with the Bluetooth configuration. - Verify that the server returns a handover select message within no
more than 3 seconds; that the message contains exactly one
alternative carrier with type
application/vnd.bluetooth.ep.oob
and power stateactive
oractivating
; that the Bluetooth local device name is transmitted; and that secure simple pairing hash and randomizer are not transmitted. Issues a warning if class of device/service or service class UUID attributes are not transmitted. - Close the data link conection.
Bluetooth secure pairing¶
$ handover-test-client.py -t 5
Verify that the application/vnd.bluetooth.ep.oob
alternative
carrier is correctly evaluated and replied. This test is only
applicable if the peer device does have Bluetooth connectivity.
- Connect to the remote handover service.
- Send a handover request message with a single alternative carrier
of type
application/vnd.bluetooth.ep.oob
and power stateactive
. Secure pairing hash and randomizer are transmitted with the Bluetooth configuration. - Verify that the server returns a handover select message within no
more than 3 seconds; that the message contains exactly one
alternative carrier with type
application/vnd.bluetooth.ep.oob
and power stateactive
oractivating
; that the Bluetooth local device name is transmitted; and that secure simple pairing hash and randomizer are transmitted. Issues a warning if class of device/service or service class UUID attributes are not transmitted. - Close the data link conection.
Unknown carrier type¶
$ handover-test-client.py -t 6
Verify that the remote handover server returns a select message without alternative carriers if a single carrier of unknown type was sent with the handover request.
- Connect to the remote handover service.
- Send a handover request message with a single alternative carrier
of type
urn:nfc:ext:nfcpy.org:unknown-carrier-type
. - Verify that the server returns a handover select message with an empty alternative carrier selection.
- Close the data link conection.
Two handover requests¶
$ handover-test-client.py -t 7
Verify that the remote handover server does not close the data link connection after the first handover request message.
- Connect to the remote handover service.
- Send a handover request with a single carrier of unknown type
- Send a handover request with a single Bluetooth carrier
- Close the data link conection.
Reserved-future-use check¶
$ handover-test-client.py -t 8
Verify that reserved bits are set to zero and optional reserved bytes are not present in the payload of the alternative carrier record. This test requires that the remote server selects a Bluetooth alternative carrier if present in the request.
- Connect to the remote handover service.
- Send a handover request with a single Bluetooth carrier
- Verify that an alternative carrier record is present; that reserved bits in the first octet are zero; and that the record payload ends with the last auxiliary data reference.
- Close the data link conection.
Skip meaningless records¶
$ handover-test-client.py -t 9
Verify that records that have no defined meaning in the payload of a handover request record are ignored. This test assumes that the remote server selects a Bluetooth alternative carrier if present in the request.
- Connect to the remote handover service.
- Send a handover request with a single Bluetooth carrier and a meaningless text record as the first record of the handover request record payload.
- Verify that an Bluetooth alternative carrier record is returned.
- Close the data link conection.
Personal Health Device Communication¶
phdc-test-manager.py¶
This program implements an NFC device that provides a PHDC manager
with the well-known service name urn:nfc:sn:phdc
and a
non-standard PHDC manager with the experimental service name
urn:nfc:xsn:nfc-forum.org:phdc-validation
.
Usage
$ phdc-test-manager.py [-h|--help] [OPTION]...
Options
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
--mode
{t,i}
¶ Restrict the choice of NFC-DEP connection setup role to either
Target
(only listen) orInitiator
(only poll). If this option is not given the dafault is to alternate between both roles with a randomized listen time.
-
--miu
INT
¶ Set a specific value for the LLCP Link MIU. The dafault value is 2175 octets.
-
--lto
INT
¶ Set a specific LLCP Link Timeout value. The default link timeout is 500 milliseconds.
-
--listen-time
INT
¶ Set the time to listen for initialization command from an NFC-DEP Initiator. The default listen time is 250 milliseconds.
-
--no-aggregation
¶
Disable outbound packet aggregation for LLCP, i.e. do not generate LLCP AGF PDUs if multiple packets are waiting to be send. This is mostly to achieve communication with some older/buggy implementations.
-
--wait
¶
After reading or writing a tag wait until it is removed before returning. This option is implicit when the option
--loop
is set. Only relevant for reader/writer mode.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
phdc-test-agent.py p2p¶
Usage
$ phdc-test-agent.py p2p [-h|--help] [OPTION]...
Options
-
-t
N
,
--test
N
¶ Run test number N. May be set more than once.
-
-T
,
--test-all
¶
Run all tests.
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
--mode
{t,i}
¶ Restrict the choice of NFC-DEP connection setup role to either
Target
(only listen) orInitiator
(only poll). If this option is not given the dafault is to alternate between both roles with a randomized listen time.
-
--miu
INT
¶ Set a specific value for the LLCP Link MIU. The dafault value is 2175 octets.
-
--lto
INT
¶ Set a specific LLCP Link Timeout value. The default link timeout is 500 milliseconds.
-
--listen-time
INT
¶ Set the time to listen for initialization command from an NFC-DEP Initiator. The default listen time is 250 milliseconds.
-
--no-aggregation
¶
Disable outbound packet aggregation for LLCP, i.e. do not generate LLCP AGF PDUs if multiple packets are waiting to be send. This is mostly to achieve communication with some older/buggy implementations.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
Test Scenarios¶
Connect, Associate and Release¶
$ phdc-test-agent.py p2p -t 1
Verify that the Agent can connect to the PHDC Manager, associate with the IEEE Manager and finally release the association.
- Establish communication distance between the Thermometer Peer Agent and the Manager device.
- Connect to the
urn:nfc:sn:phdc
service. - Send a Thermometer Association Request.
- Verify that the Manager sends a Thermometer Association Response.
- Wait 3 seconds not sending any IEEE APDU, then send an Association Release Request.
- Verify that the Manager sends an Association Release Response
- Disconnect from the
urn:nfc:sn:phdc
service. - Move Agent and Manager device out of communication range.
Association after Release¶
$ phdc-test-agent.py p2p -t 2
Verify that the Agent can again associate with the Manager after a first association has been established and released.
- Establish communication distance between the Thermometer Peer Agent and the Manager device.
- Connect to the
urn:nfc:sn:phdc
service. - Send a Thermometer Association Request.
- Verify that the Manager sends a Thermometer Association Response.
- Disconnect from the
urn:nfc:sn:phdc
service. - Connect to the
urn:nfc:sn:phdc
service. - Send a Thermometer Association Request.
- Verify that the Manager sends a Thermometer Association Response.
- Send a Association Release Request.
- Verify that the Manager sends a Association Release Response.
- Disconnect from the
urn:nfc:sn:phdc
service. - Move Agent and Manager device out of communication range.
PHDC PDU Fragmentation and Reassembly¶
$ phdc-test-agent.py p2p -t 3
Verify that large PHDC PDUs are correctly fragmented and reassembled.
- Establish communication distance between the Validation Agent and the Manager device.
- Connect to the
urn:nfc:xsn:nfc-forum.org:phdc-validation
service. - Send a PHDC PDU with an Information field of 2176 random octets.
- Verify to receive an PHDC PDU that contains the same random octets in reversed order.
- Disconnect from the
urn:nfc:xsn:nfc-forum.org:phdc-validation
service. - Move Agent and Manager device out of communication range.
phdc-test-agent.py tag¶
Usage
$ phdc-test-agent.py tag [-h|--help] [OPTION]...
Options
-
-t
N
,
--test
N
¶ Run test number N. May be set more than once.
-
-T
,
--test-all
¶
Run all tests.
-
--loop
,
-l
¶
Repeat the command endlessly, use Control-C to abort.
-
-q
¶
Do not print log messages except for errors and warnings.
-
-d
MODULE
¶ Output debug messages for MODULE to the log facility. Logs are written to <stderr> unless a log file is set with
-f
. MODULE is a string that corresponds to an nfcpy module or individual file, with dots between path components. For example,-d nfc
enables all nfcpy debug logs,-d nfc.tag
enables debug logs for all tag types, and-d nfc.tag.tt3
enables debug logs only for type 3 tags. This option may be given multiple times to enable debug logs for several modules.
-
-f
LOGFILE
¶ Write debug log messages to <LOGFILE> instead of <stderr>. Info, warning and error logs will still be printed to <stderr> unless
-q
is set to supress info messages on <stderr>.
-
--nolog-symm
¶
When operating in peer mode this option prevents logging of LLCP Symmetry PDUs from the
nfc.llcp.llc
module. Symmetry PDUs are exchanged regularly and quite frequently over an LLCP Link and are logged by default if debug output is enabled for the llcp module.
-
--device
PATH
¶ Use a specific reader or search only for a subset of readers. The syntax for PATH is:
usb[:vendor[:product]]
with optional vendor and product as four digit hexadecimal numbers, likeusb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader.usb[:bus[:device]]
with optional bus and device number as three-digit decimal numbers, likeusb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1.tty:port:driver
with mandatory port and driver name should be used on Posix systems to open the serial port at device node/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
.com:port:driver
with mandatory port and driver name should be used on Windows systems to open the serial portCOM<port>
and load thenfc/dev/<driver>.py
driver module.udp[:host][:port]
with optional host name or address and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
Test Scenarios¶
Discovery, Association and Release¶
$ phdc-test-agent.py tag -t 1
Verify that a PHDC Tag Agent is discovered by a PHDC Manager and IEEE APDU exchange is successful.
- Establish communication distance between the Thermometer Tag Agent and the Manager.
- Send a Thermometer Association Request.
- Verify that the Manager sends a Thermometer Association Response.
- Wait 3 seconds not sending any IEEE APDU, then send an Association Release Request.
- Verify that the Manager sends a Association Release Response.
- Move Thermometer Tag Agent and Manager out of communication range.
Association after Release¶
$ phdc-test-agent.py tag -t 2
Verify that a Tag Agent can again associate with the Manager after a first association has been established and released.
- Establish communication distance between the Thermometer Tag Agent and the Manager.
- Send a Thermometer Association Request.
- Verify that the Manager sends a Thermometer Association Response.
- Send an Association Release Request.
- Verify that the Manager sends a Association Release Response.
- Wait 3 seconds not sending any IEEE APDU, then send a Thermometer Association Request.
- Verify that the Manager sends a Thermometer Association Response.
- Move Thermometer Tag Agent and Manager out of communication range.
Activation with invalid settings¶
$ phdc-test-agent.py tag -t 3
Verify that a PHDC Manager refuses communication with a Tag Agent that presents an invalid PHDC record payload during activation.
- Establish communication distance between the Tag Agent and the Manager.
- Send the first PHDC PDU with invalid settings in one or any of the MC, LC or MD fields.
- Verify that the Manager stops further PHDC communication with the Tag Agent.
Activation with invalid RFU value¶
$ phdc-test-agent.py tag -t 4
Verify that a PHDC Manager communicates with a Tag Agent that presents a PHDC record payload with an invalid RFU value during activation.
- Establish communication distance between the Tag Agent and the Manager.
- Send the first PHDC PDU with an invalid value in the RFU field.
- Verify that the Manager continues PHDC communication with the Tag Agent.
Generate Test Tags¶
This page contains instructions to generate tags for testing reader
compliance with NFC Forum Tag Type, NDEF and RTD specifications. The
tools used are in the examples
directory.
Type 3 Tags¶
Attribute Block Tests¶
This is a collection of tags to test processing of the the Type 3 Tag attribute information block. These can be used to verify if the NFC device correctly reads or writes tags with different attribute information, both valid and invalid. Below figure (from the NFC Forum Type 3 Tag Operation Specification) shows the Attribute Information Format.
TT3_READ_BV_001¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation hosted on readthedocs" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 80 --max 5 --rw 0
- Settings: Len = Nmaxb * 16, RWFlag = 0x00
- Expected: Fully used tag. Read all data stored (Len)
TT3_READ_BV_002¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 58 --rw 0 --nbr 1
- Settings: Nbr = 1, RWFlag = 0x00
- Expected: Identify as „Read Only“ (normal read-only tag, read only 1 block at a time)
TT3_READ_BV_003¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 58 --rw 0 --max 3
- Nbr > Nbmax, RWFlag = 0x00
- Read Nbmax blocks (NOT read Nbr blocks)
TT3_READ_BV_004¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 58 --rw 0 --wf 15
- WriteFlag = 0x0F, RWFlag = 0x00
- Identify as „corrupted data“ (previous write interrupted)
TT3_READ_BV_005¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 58 --rw 0 --max 3
- Nmaxb * 16 < Len, RWFlag = 0x00
- Identify as „Corrupted data“ (invalid length)
TT3_READ_BV_006¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t `python -c 'print(810*"nfcpy")'` | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 4495 --rw 0
- Nmaxb > 255, Len > 255, RWFlag = 0x00
- Read all data. Identify as „Read Only“. Write prohibited. (normal read-only tag)
- Requires a tag with more than 4 kbyte NDEF capacity
TT3_READ_BI_001¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 58 --rw 0 --nbr 0 --nbw 0
- Nbr = 0, Nbw = 0, RWFlag = 0x00
- Identify as „Corrupted data“ (invalid attribute information block)
TT3_READ_BI_002¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 58 --rw 0 --crc 4660
- Checksum invalid, RWFlag = 0x00
- Identify as „Corrupted data“ (invalid attribute information block)
TT3_READ_BI_003¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 58 --rw 0 --ver 2.0
- Version = 2.0, RWFlag = 0x00
- Identify as unknown version
TT3_READ_BI_004¶
$ ./tagtool.py format
$ ./ndeftool.py make smartposter http://nfcpy.readthedocs.org/ -t "nfcpy documentation" | ./tagtool.py load -
$ ./tagtool.py format tt3 --len 58 --rw 0 --rfu 255
- All unused bytes in attribute block = 0xFF
- Ignore when reading RWFlag = 0x00
TT3_WRITE_BV_001¶
$ ./tagtool.py format tt3 --rw 0
- RWFlag = 0x00, no content
- Identify as „Read Only“. Write prohibited. (normal read-only tag)
TT3_WRITE_BV_002¶
$ ./tagtool.py format tt3 --rw 1
- RWFlag = 0x01, no content
- Identify as „Read/Write“. Write permitted. (normal writtable tag)
TT3_WRITE_BV_003¶
$ ./tagtool.py format tt3 --rw 0 --max 4
- Nbw > Nbmax, RWFlag = 0x01
- Write Nbmax blocks (not write Nbw blocks)
Module Reference¶
nfc¶
nfc.ContactlessFrontend¶
-
class
nfc.
ContactlessFrontend
(path=None)¶ The contactless frontend is the main interface class for working with contactless reader devices. A reader device may be opened when an instance is created by providing the path argument, see
nfc.ContactlessFrontend.open()
for how it must be constructed.The initializer method raises
IOError(errno.ENODEV)
if a path is specified but no no reader are found.-
open
(path)¶ Open a contactless reader device identified by path.
Parameters: path – search path for contactless reader Returns True: if reader was found and activated Path specification:
usb[:vendor[:product]]
- with optional vendor and product as four digit
hexadecimal numbers, like
usb:054c:06c3
would open the first Sony RC-S380 reader andusb:054c
the first Sony reader. usb[:bus[:device]]
- with optional bus and device number as three-digit
decimal numbers, like
usb:001:023
would specifically mean the usb device with bus number 1 and device id 23 whereasusb:001
would mean to use the first available reader on bus number 1. tty:port:driver
- with mandatory port and driver name should be used on
Posix systems to open the serial port at device node
/dev/tty<port>
and load the driver from modulenfc/dev/<driver>.py
. A typical example would betty:USB0:arygon
for the Arygon APPx/ADRx at/dev/ttyUSB0
. com:port:driver
- with mandatory port and driver name should be used on
Windows systems to open the serial port
COM<port>
and load thenfc/dev/<driver>.py
driver module. udp[:host][:port]
with optional host name or address- and port number will use a fake communication channel over UDP/IP. Either value may be omitted in which case host defaults to ‘localhost’ and port defaults to 54321.
-
close
()¶ Close the contacless reader device.
-
connect
(**options)¶ Connect with a contactless target or become connected as a contactless target. The calling thread is blocked until a single activation and deactivation has completed or a callback function supplied as the keyword argument
terminate
returned True. The result of the terminate function also applies to the loop run after activation, so the example below will makeconnect()
return after 10 seconds from either waiting for a peer device or when connected.>>> import nfc, time >>> clf = nfc.ContactlessFrontend('usb') >>> after5s = lambda: time.time() - started > 5 >>> started = time.time(); clf.connect(llcp={}, terminate=after5s)
Connect options are given as keyword arguments with dictionary values. Possible options are:
rdwr={key: value, ...}
- options for reader/writer operationllcp={key: value, ...}
- options for peer to peer mode operationcard={key: value, ...}
- options for card emulation operation
Reader/Writer Options
- ‘targets’: sequence
- A list of target specifications with each target of either
type
TTA
,TTB
, orTTF
. A default set is choosen if ‘targets’ is not provided. - ‘on-startup’: function
- A function that will be called with the list of targets
(from ‘targets’) to search for. Must return a list of
targets or
None
. Only the targets returned are finally considered. - ‘on-connect’: function
- A function object that will be called with an activated
Tag
object.
>>> import nfc >>> def connected(tag): ... print tag ... return True ... >>> clf = nfc.ContactlessFrontend() >>> clf.connect(rdwr={'on-connect': connected}) Type3Tag IDm=01010501b00ac30b PMm=03014b024f4993ff SYS=12fc True
Peer To Peer Options
- ‘on-startup’: function
- A function that is called before an attempt is made to
establish peer to peer communication. The function receives
the initialized
LogicalLinkController
instance as parameter, which may then be used to allocate and bind communication sockets for service applications. The return value must be either theLogicalLinkController
instance orNone
to effectively remove llcp from the options considered. - ‘on-connect’: function
- A function that is be called when peer to peer communication
was established. The function receives the connected
LogicalLinkController
instance as parameter, which may then be used to allocate communication sockets withsocket()
and spawn working threads to perform communication. The callback must return more or less immediately withTrue
unless the logical link controller run loop is handled within the callback. - ‘role’: string
- Defines which role the local LLC shall take for the data exchange protocol activation. Possible values are ‘initiator’ and ‘target’. The default is to alternate between both roles until communication is established.
- ‘miu’: integer
- Defines the maximum information unit size that will be supported and announced to the remote LLC. The default value is 128.
- ‘lto’: integer
- Defines the link timeout value (in milliseconds) that will be announced to the remote LLC. The default value is 100 milliseconds.
- ‘agf’: boolean
- Defines if the local LLC performs PDU aggregation and may thus send Aggregated Frame (AGF) PDUs to the remote LLC. The dafault is to use aggregation.
>>> import nfc >>> import threading >>> def worker(socket): ... socket.sendto("Hi there!", address=16) ... socket.close() ... >>> def connected(llc): ... socket = llc.socket(nfc.llcp.LOGICAL_DATA_LINK) ... threading.Thread(target=worker, args=(socket,)).start() ... return True ... >>> clf = nfc.ContactlessFrontend() >>> clf.connect(llcp={'on-connect': connected})
Card Emulation Options
- ‘targets’: sequence
- A list of target specifications with each target of either
type
TTA
,TTB
, orTTF
. The list of targets is processed sequentially. Defaults to an empty list. - ‘on-startup’: function
- A function that will be called with the list of targets
(from ‘targets’) to emulate. Must return a list of one
target choosen or
None
. - ‘on-connect’: function
- A function that will be called with an activated
TagEmulation
instance as first parameter and the first command received as the second parameter. - ‘on-release’: function A function that will be called when the
- activated tag has been released by it’s Initiator, basically that is when the tag has been removed from the Initiator’s RF field.
- ‘timeout’: integer
- The timeout in seconds to wait for for each target to become initialized. The default value is 1 second.
>>> import nfc >>> >>> def connected(tag, command): ... print tag ... print str(command).encode("hex") ... >>> clf = nfc.ContactlessFrontend() >>> idm = bytearray.fromhex("01010501b00ac30b") >>> pmm = bytearray.fromhex("03014b024f4993ff") >>> sys = bytearray.fromhex("12fc") >>> target = nfc.clf.TTF(212, idm, pmm, sys) >>> clf.connect(card={'targets': [target], 'on-connect': connected}) Type3TagEmulation IDm=01010501b00ac30b PMm=03014b024f4993ff SYS=12fc 100601010501b00ac30b010b00018000 True
Connect returns
None
if no options were to execute,False
if interrupted by aKeyboardInterrupt
, orTrue
if terminated normally and the ‘on-connect’ callback function had returnedTrue
. If the ‘on-connect’ callback had returnedFalse
the return value of connect() is the same parameters as were provided to the callback function.Connect raises
IOError(errno.ENODEV)
if called before a contactless reader was opened.
-
sense
(targets, **kwargs)¶ Send discovery and activation requests to find a target. Targets is a list of target specifications (TTA, TTB, TTF). Not all readers may support all possible target types. The return value is an activated target with a possibly updated specification (bitrate) or None.
Additional keyword arguments are driver specific.
Note
This is a direct interface to the driver and not needed if
connect()
is used.
-
listen
(target, timeout)¶ Listen for timeout seconds to become initialized as a target. The target must be one of
nfc.clf.TTA
,nfc.clf.TTB
,nfc.clf.TTF
, ornfc.clf.DEP
(note that target type support depends on the hardware capabilities). The return value isNone
if timeout elapsed without activation or a tuple (target, command) where target is the activated target (which may differ from the requested target, see below) and command is the first command received from the initiator.If an activated target is returned, the target type and attributes may differ from the target requested. This is especically true if activation as a
nfc.clf.DEP
target is requested but the contactless frontend does not have a hardware implementation of the data exchange protocol and returns anfc.clf.TTA
ornfc.clf.TTF
target instead.Note
This is a direct interface to the driver and not needed if
connect()
is used.
-
exchange
(send_data, timeout)¶ Exchange data with an activated target (data is a command frame) or as an activated target (data is a response frame). Returns a target response frame (if data is send to an activated target) or a next command frame (if data is send from an activated target). Returns None if the communication link broke during exchange (if data is sent as a target). The timeout is the number of seconds to wait for data to return, if the timeout expires an nfc.clf.TimeoutException is raised. Other nfc.clf.DigitalProtocolExceptions may be raised if an error is detected during communication.
Note
This is a direct interface to the driver and not needed if
connect()
is used.
-
set_communication_mode
(brm, **kwargs)¶ Set the hardware communication mode. The effect of calling this method depends on the hardware support, some drivers may purposely ignore this function. If supported, the parameter brm specifies the communication mode to choose as a string composed of the bitrate and modulation type, for example ‘212F’ shall switch to 212 kbps Type F communication. Other communication parameters may be changed with optional keyword arguments. Currently implemented by the RC-S380 driver are the parameters ‘add-crc’ and ‘check-crc’ when running as initator. It is possible to set brm to an empty string if bitrate and modulation shall not be changed but only optional parameters executed.
Note
This is a direct interface to the driver and not needed if
connect()
is used.
-
-
class
nfc.clf.
TTA
(br=None, cfg=None, uid=None, ats=None)¶ Represents a Type A target. The integer br is the bitrate. The bytearray cf is the two byte SENS_RES data plus the one byte SEL_RES data for a tag type 1/4 tag. The bytearray uid is the target UID. The bytearray ats is the answer to select data of a type 4 tag if the chipset does activation as part of discovery.
-
class
nfc.clf.
TTB
(br=None)¶ Represents a Type B target. The integer br is the bitrate. Type B targets are not yet supported in nfcpy, for the simple reason that no cards for testing are available.
-
class
nfc.clf.
TTF
(br=None, idm=None, pmm=None, sys=None)¶ Represents a Type F target. The integer br is the bitrate. The bytearray idm is the 8 byte manufacture id. The bytearray pmm is the 8 byte manufacture parameter. The bytearray sys is the 2 byte system code.
-
class
nfc.clf.
DEP
(br=None, gb=None)¶ Represents a DEP target. The integer br is the bitrate. The bytearray gb is the ATR general bytes.
nfc.tag¶
nfc.tag.tt1.Type1Tag¶
-
class
nfc.tag.tt1.
Type1Tag
¶ -
is_present
¶ Returns True if the tag is still within communication range.
-
read_id
()¶ Read header rom and all static memory bytes (blocks 0-14).
-
read_all
()¶ Read header rom and all static memory bytes (blocks 0-14).
-
read_byte
(addr)¶ Read a single byte from static memory area (blocks 0-14).
-
write_byte
(addr, byte, erase=True)¶ Write a single byte to static memory area (blocks 0-14). The target byte is zero’d first if ‘erase’ is True (default).
-
read_block
(block)¶ Read an 8-byte data block at address (block * 8).
-
write_block
(block, data, erase=True)¶ Write an 8-byte data block at address (block * 8). The target bytes are zero’d first if ‘erase’ is True (default).
-
nfc.tag.tt2.Type2Tag¶
-
class
nfc.tag.tt2.
Type2Tag
¶ -
is_present
¶ Returns True if the tag is still within communication range.
-
read
(block)¶ Read 16-byte of data from the tag. The block argument specifies the offset in multiples of 4 bytes (i.e. block number 1 will return bytes 4 to 19). The data returned is a byte array of length 16.
-
write
(block, data)¶ Write 4-byte of data to the tag. The block argument specifies the offset in multiples of 4 bytes. The data argument must be a string or bytearray of length 4.
-
nfc.tag.tt3.Type3Tag¶
-
class
nfc.tag.tt3.
Type3Tag
¶ -
is_present
¶ True if the tag is still within communication range.
-
poll
(system_code)¶ Send the polling command to recognize a system on the card. The system_code may be specified as a short integer or as a string or bytearray of length 2. The return value is the tuple of the two bytearrays (idm, pmm) if the requested system is present or the tuple (None, None) if not.
-
read
(blocks, service=11)¶ Read service data blocks from tag. The service argument is the tag type 3 service code to use, 0x000b for reading NDEF. The blocks argument holds a list of integers representing the block numbers to read. The data is returned as a character string.
-
write
(data, blocks, service=9)¶ Write service data blocks to tag. The service argument is the tag type 3 service code to use, 0x0009 for writing NDEF. The blocks argument holds a list of integers representing the block numbers to write. The data argument must be a character string with length equal to the number of blocks times 16.
-
nfc.tag.tt4.Type4Tag¶
-
class
nfc.tag.tt4.
Type4Tag
¶ -
is_present
¶ True if the tag is still within communication range.
-
select_file
(p1, p2, data, expected_response_length=None)¶ Select a file or directory with parameters defined in ISO/IEC 7816-4
-
read_binary
(offset, count)¶ Read count bytes from selected file starting at offset
-
update_binary
(offset, data)¶ Write data bytes to selected file starting at offset
-
nfc.ndef¶
- nfc.ndef.Message
- nfc.ndef.Record
- nfc.ndef.TextRecord
- nfc.ndef.UriRecord
- nfc.ndef.SmartPosterRecord
- nfc.ndef.HandoverRequestMessage
- nfc.ndef.HandoverSelectMessage
- nfc.ndef.HandoverCarrierRecord
- nfc.ndef.handover.Version
- nfc.ndef.handover.Carrier
- nfc.ndef.handover.HandoverError
- nfc.ndef.BluetoothConfigRecord
- nfc.ndef.WifiConfigRecord
- nfc.ndef.WifiPasswordRecord
Support for decoding and encoding of NFC Data Exchange Format (NDEF) records and messages.
nfc.ndef.Message¶
-
class
nfc.ndef.
Message
(*args)¶ Wraps a sequence of NDEF records and provides methods for appending, inserting and indexing. Instantiation accepts a variable number of positional arguments. A call without argument produces a Message object with no records. A single str or bytearray argument is parsed as NDEF message bytes. A single list or tuple of
nfc.ndef.Record
objects produces a Message with those records in order. One or morenfc.ndef.Record
arguments produce a Message with those records in order.>>> nfc.ndef.Message(b'\x10\x00\x00') # NDEF data bytes >>> nfc.ndef.Message(bytearray([16,0,0])) # NDEF data bytes >>> nfc.ndef.Message([record1, record2]) # list of records >>> nfc.ndef.Message(record1, record2) # two record args
-
append
(record)¶ Add a record to the end of the message. The record argument must be an instance of
nfc.ndef.Record
.
-
extend
(records)¶ Extend the message by appending all the records in the given list. The records argument must be a sequence of
nfc.ndef.Record
elements.
-
insert
(i, record)¶ Insert a record at the given position. The first argument i is the index of the record before which to insert, so message.insert(0, record) inserts at the front of the message, and message.insert(len(message), record) is equivalent to message.append(record). The second argument record must be an instance of
nfc.ndef.Record
.
-
pop
(i=-1)¶ Remove the record at the given position i in the message, and return it. If no position is specified, message.pop() removes and returns the last item.
-
type
¶ The message type. Corresponds to the record type of the first record in the message. None if the message has no records. This attribute is read-only.
-
name
¶ The message name. Corresponds to the record name of the first record in the message. None if the message has no records. This attribute is read-only.
-
pretty
()¶ Returns a message representation that might be considered pretty-printable.
-
nfc.ndef.Record¶
-
class
nfc.ndef.
Record
(record_type=None, record_name=None, data=None)¶ Wraps an NDEF record and provides getting and setting of the record type name (
type
), record identifier (name
) and record payload (data
).Parameters: - record_type – NDEF record type name
- record_name – NDEF record identifier
- data – NDEF record payload or NDEF record data
All arguments accept a
str
orbytearray
object.Interpretation of the data argument depends on the presence of record_type and record_name. If any of the record_type or record_name argument is present, the data argument is interpreted as the record payload and copied to
data
. If none of the record_type or record_name argument are present, the data argument is interpreted as a NDEF record bytes (NDEF header and payload) and parsed.The record_type argument combines the NDEF TNF (Type Name Format) and NDEF TYPE information into a single string. The TNF values 0, 5 and 6 are expressed by the strings ‘’, ‘unknown’ and ‘unchanged’. For TNF values 2 and 4 the record_type is the prefix ‘urn:nfc:wkt:’ and ‘urn:nfc:ext:’, respectively, followed by the NDEF TYPE string. TNF values 2 and 3 are not distinguished by regular expressions matching the either the media-type format ‘type-name/subtype-name’ or absolute URI format ‘scheme:hier-part’
>>> nfc.ndef.Record('urn:nfc:wkt:T', 'id', b'enHello World') >>> nfc.ndef.Record('urn:nfc:wkt:T', data=b'enHello World') >>> nfc.ndef.Record(data=b'ÑTenHello World')
-
type
¶ The record type. A string that matches the empty string ‘’, or the string ‘unknown’, or the string ‘unchanged’, or starts with ‘urn:nfc:wkt:’, or starts with ‘urn:nfc:ext:’, or matches the mime-type format, or matches the absolute-URI format.
-
name
¶ The record identifier as an octet string. Any type that can be coverted into a sequence of characters in range(0,256) can be assigned.
-
data
¶ The record payload as an octet string. Any type that can be coverted into a sequence of characters in range(0,256) can be assigned.
-
pretty
(indent=0)¶ Returns a string with a formatted representation that might be considered pretty-printable. The optional argument indent specifies the amount of indentation added for each level of output.
nfc.ndef.TextRecord¶
-
class
nfc.ndef.
TextRecord
(text=None, language='en', encoding='UTF-8')¶ Bases:
nfc.ndef.record.Record
Wraps an NDEF Text record and provides access to the
encoding
,language
and actualtext
content.Parameters: - text – Text string or
nfc.ndef.Record
object - language – ISO/IANA language code string
- encoding – Text encoding in binary NDEF
The text argument may alternatively supply an instance of class
nfc.ndef.Record
. Initialization is then done by parsing the record payload. If the record type does not match ‘urn:nfc:wkt:T‘ aValueError
exception is raised.>>> nfc.ndef.TextRecord(nfc.ndef.Record()) >>> nfc.ndef.TextRecord("English UTF-8 encoded") >>> nfc.ndef.TextRecord("Deutsch UTF-8", language="de") >>> nfc.ndef.TextRecord("English UTF-16", encoding="UTF-16")
-
text
¶ The text content. A unicode string that specifies the TEXT record text field. Coerced into unicode when set.
-
language
¶ The text language. A string that specifies the ISO/IANA language code coded into the TEXT record. The value is not verified except that a
ValueError
exception is raised if the assigned value string exceeds 64 characters.
-
encoding
¶ The text encoding, given as a string. May be ‘UTF-8’ or ‘UTF-16’. A
ValueError
exception is raised for anythinge else.
- text – Text string or
nfc.ndef.UriRecord¶
-
class
nfc.ndef.
UriRecord
(uri=None)¶ Bases:
nfc.ndef.record.Record
Wraps an NDEF URI record and provides access to the
uri
content. The URI RTD specification defines the payload of the URI record as a URI identifier code byte followed by a URI string. The URI identifier code provides one byte code points for abbreviations of commonly used URI protocol names. TheUriRecord
class handles abbreviations transparently by expanding and compressing when decoding and encoding.Parameters: uri – URI string or nfc.ndef.Record
objectThe uri argument may alternatively supply an instance of class
nfc.ndef.Record
. Initialization is then done by parsing the record payload. If the record type does not match ‘urn:nfc:wkt:U‘ aValueError
exception is raised.>>> nfc.ndef.UriRecord(nfc.ndef.Record()) >>> nfc.ndef.UriRecord("http://nfcpy.org")
-
uri
¶ The URI string, including any abbreviation that is possibly available. A
ValueError
exception is raised if the string contains non ascii characters.
-
nfc.ndef.SmartPosterRecord¶
-
class
nfc.ndef.
SmartPosterRecord
(uri, title={}, icons={}, action='default', resource_size=None, resource_type=None)¶ Bases:
nfc.ndef.record.Record
Wraps an NDEF SmartPoster record and provides access to the
encoding
,language
and actualtext
content.Parameters: - uri – URI string or
nfc.ndef.Record
object - title – Smart poster title(s), assigned to
title
- icons – Smart poster icons, assigned to
icons
- action – Recommended action, assigned to
action
- resource_size – Size of the referenced resource
- resource_type – Type of the referenced resource
The uri argument may alternatively supply an instance of class
nfc.ndef.Record
. Initialization is then done by parsing the record payload. If the record type does not match ‘urn:nfc:wkt:Sp‘ aValueError
exception is raised.>>> nfc.ndef.SmartPosterRecord(nfc.ndef.Record()) >>> nfc.ndef.SmartPosterRecord("http://nfcpy.org", "nfcpy") >>> nfc.ndef.SmartPosterRecord("http://nfcpy.org", "nfcpy", action="save")
-
uri
¶ The smart poster URI, a string of ascii characters. A
ValueError
exception is raised if non ascii characters are contained.
-
title
¶ A dictionary of smart poster titles with ISO/IANA language codes as keys and title strings as values. Set specific title strings with
obj.title['en']=title
. Assigning a string value is equivalent to setting the title for language code ‘en’. Titles are optional for a smart poster record
-
icons
¶ A dictionary of smart poster icon images. The keys specify the image mime sub-type and the values are strings of image data. Icons are optional for a smart poster record.
-
action
¶ The recommended action for the receiver of the smart poster. Reads as ‘default’, ‘exec’, ‘save’, ‘edit’ or a number string if RFU values were decoded. Can be set to ‘exec’, ‘save’, ‘edit’ or
None
. The action is optional in a smart poster record.
-
resource_size
¶ The size of the resource referred by the URI. A 32 bit unsigned integer value or
None
. The resource size is optional in a smart poster record.
-
resource_type
¶ The type of the resource referred by the URI. A UTF-8 formatted string that describes an Internet media type (MIME type) or
None
. The resource type is optional in a smart poster record.
- uri – URI string or
nfc.ndef.HandoverRequestMessage¶
-
class
nfc.ndef.
HandoverRequestMessage
(message=None, version=None)¶ The handover request message is used in the the NFC Connection Handover protocol to send proposals for alternative carriers to a peer device.
Parameters: - message (
nfc.ndef.Message
) – a parsed message with type ‘urn:nfc:wkt:Hr‘ - version (
str
) – a ‘<major-number>.<minor-number>’ version string
Either the message or version argument must be supplied. A
ValueError
is raised if both arguments are present or absent.The message argument must be a parsed NDEF message with, according to the Connection Handover Specification, at least two records. The first record, and thus the message, must match the NFC Forum Well-Known Type ‘urn:nfc:wkt:Hr‘.
The version argument indicates the Connection Handover version that shall be used for encoding the handover request message NDEF data. It is currently limited to major-version ‘1’ and minor-version ‘0’ to ‘15’ and for any other value a
ValueError
exception is raised.>>> nfc.ndef.HandoverRequestMessage(nfc.ndef.Message(ndef_message_data)) >>> nfc.ndef.HandoverRequestMessage(version='1.2')
-
type
¶ The message type. This is a read-only attribute which returns the NFC Forum Well-Known Type ‘urn:nfc:wkt:Hr‘
-
name
¶ The message name (identifier). Corresponds to the name of the handover request record.
-
version
¶ Connection Handover version number that the messsage complies to. A read-only
Version
object that provides the major and minor versionint
values.
-
nonce
¶ A nonce received or to be send as the random number for handover request collision resolution. This attribute is supported only since version 1.2.
-
carriers
¶ List of alternative carriers. Each entry is an
Carrier
object that holds properties of the alternative carrier. Useadd_carrier()
to expand this list.
-
add_carrier
(carrier_record, power_state, aux_data_records=None)¶ Add a new carrier to the handover request message.
Parameters: - carrier_record (
nfc.ndef.Record
) – a record providing carrier information - power_state (
str
) – a string describing the carrier power state - aux_data_records (
RecordList
) – list of auxiliary data records
>>> hr = nfc.ndef.HandoverRequestMessage(version="1.2") >>> hr.add_carrier(some_carrier_record, "active")
- carrier_record (
-
pretty
(indent=0)¶ Returns a string with a formatted representation that might be considered pretty-printable.
- message (
nfc.ndef.HandoverSelectMessage¶
-
class
nfc.ndef.
HandoverSelectMessage
(message=None, version=None)¶ The handover select message is used in the the NFC Connection Handover protocol to send agreements for alternative carriers to a peer device as response to a handover request message.
Parameters: - message (
nfc.ndef.Message
) – a parsed message with type ‘urn:nfc:wkt:Hs‘ - version (
str
) – a ‘<major-number>.<minor-number>’ version string
Either the message or version argument must be supplied. A
ValueError
is raised if both arguments are present or absent.The message argument must be a parsed NDEF message with, according to the Connection Handover Specification, at least one record. The first record, and thus the message, must match the NFC Forum Well-Known Type ‘urn:nfc:wkt:Hs‘.
The version argument indicates the Connection Handover version that shall be used for encoding the handover select message NDEF data. It is currently limited to major-version ‘1’ and minor-version ‘0’ to ‘15’ and for any other value a
ValueError
exception is raised.>>> nfc.ndef.HandoverSelectMessage(nfc.ndef.Message(ndef_message_data)) >>> nfc.ndef.HandoverSelectMessage(version='1.2')
-
type
¶ The message type. This is a read-only attribute which returns the NFC Forum Well-Known Type ‘urn:nfc:wkt:Hs‘
-
name
¶ The message name (identifier). Corresponds to the name of the handover select record.
-
version
¶ Connection Handover version number that the messsage complies to. A read-only
Version
object that provides the major and minor versionint
values.
-
error
¶ A
HandoverError
structure that provides error reason and data received or to be send with the handover select message. Anerror.reason
value of 0 means that no error was received or is to be send.
-
carriers
¶ List of alternative carriers. Each entry is an
Carrier
object that holds properties of the alternative carrier. Useadd_carrier()
to expand this list.
-
add_carrier
(carrier_record, power_state, aux_data_records=[])¶ Add a new carrier to the handover select message.
Parameters: - carrier_record (
nfc.ndef.Record
) – a record providing carrier information - power_state (
str
) – a string describing the carrier power state - aux_data_records (
RecordList
) – list of auxiliary data records
>>> hs = nfc.ndef.HandoverSelectMessage(version="1.2") >>> hs.add_carrier(some_carrier_record, "active")
- carrier_record (
-
pretty
(indent=0)¶ Returns a string with a formatted representation that might be considered pretty-printable.
- message (
nfc.ndef.HandoverCarrierRecord¶
-
class
nfc.ndef.
HandoverCarrierRecord
(carrier_type, carrier_data=None)¶ Bases:
nfc.ndef.record.Record
The handover carrier record is used to identify an alternative carrier technology in a handover request message when no carrier configuration data shall be transmitted.
Parameters: - carrier_type (
str
) – identification of an alternative carrier - carrier_data (
str
) – additional alternative carrier information
>>> nfc.ndef.HandoverCarrierRecord('application/vnd.bluetooth.ep.oob')
-
carrier_type
¶ Identification of an alternative carrier. A string formatted as an NFC Forum Well-Known or External Type or Internet Media Type or absolute URI. This attribute is read-only.
-
carrier_data
¶ An octet string that provides additional information about the alternative carrier.
- carrier_type (
nfc.ndef.handover.Carrier¶
-
class
nfc.ndef.handover.
Carrier
¶ -
type
¶ The alternative carrier type name, equivalent to
Carrier.record.type
orCarrier.record.carrier_type
if the carrier is specified as aHandoverCarrierRecord
.
-
record
¶ A carrier configuration record. Recognized and further interpreted records are:
HandoverCarrierRecord
,BluetoothConfigRecord
,WifiConfigRecord
,WifiPasswordRecord
.
-
power_state
¶ The carrier power state. This may be one of the following strings: “inactive”, “active”, “activating”, or “unknown”.
-
auxiliary_data_records
¶ A list of auxiliary data records providing additional carrier information.
-
nfc.ndef.BluetoothConfigRecord¶
-
class
nfc.ndef.
BluetoothConfigRecord
¶ Bases:
nfc.ndef.record.Record
-
device_address
¶ Bluetooth device address. A string of hexadecimal characters with 8-bit quantities spearated by colons and the most significant byte first. For example, the device address
'01:23:45:67:89:AB'
corresponds to0x0123456789AB
.
-
local_device_name
¶ Bluetooth Local Name encoded as sequence of characters in the given order. Received as complete (EIR type 0x09) or shortened (EIR type 0x08) local name. Transmitted as complete local name. Set to None if not received or not to be transmitted.
-
simple_pairing_hash
¶ Simple Pairing Hash C. Received and transmitted as EIR type 0x0E. Set to None if not received or not to be transmitted. Raises nfc.ndef.DecodeError if the received value or nfc.ndef.EncodeError if the assigned value is not a sequence of 16 octets.
-
simple_pairing_rand
¶ Simple Pairing Randomizer R. Received and transmitted as EIR type 0x0F. Set to None if not received or not to be transmitted. Raises nfc.ndef.DecodeError if the received value or nfc.ndef.EncodeError if the assigned value is not a sequence of 16 octets.
-
service_class_uuid_list
¶ Listq of Service Class UUIDs. Set and retrieved as a list of complete 128-bit UUIDs. Decoded from and encoded as EIR types 0x02/0x03 (16-bit partial/complete UUIDs), 0x04/0x05 (32-bit partial/complete UUIDs), 0x06/0x07 (128-bit partial/complete UUIDs).
-
class_of_device
¶ Class of Device encoded as unsigned long integer. Received and transmitted as EIR type 0x0D in little endian byte order. Set to None if not received or not to be transmitted.
-
nfc.ndef.WifiConfigRecord¶
-
class
nfc.ndef.
WifiConfigRecord
¶ Bases:
nfc.ndef.record.Record
-
version
¶ The WiFi Simple Configuration version, coded as a ‘major.minor’ string
-
credentials
¶ A list of WiFi credentials. Each credential is a dictionary with any of the possible keys
'network-name'
,'network-key'
,'shareable'
,'authentication'
,'encryption'
,'mac-address'
, and'other'
.
-
credential
¶ The first WiFi credential. Same as
WifiConfigRecord().credentials[0]
.
-
other
¶ A list of WiFi attribute (key, value) pairs other than version and credential(s). Keys are two character strings for standard WiFi attributes, one character strings for subelements within a WFA vendor extension attribute, and three character strings for other vendor ecxtension attributes.
-
nfc.ndef.WifiPasswordRecord¶
-
class
nfc.ndef.
WifiPasswordRecord
¶ Bases:
nfc.ndef.record.Record
-
version
¶ The WiFi Simple Configuration version, coded as a ‘major.minor’ string
-
passwords
¶ A list of WiFi out-of-band device passwords. Each password is a dictionary with the keys
'public-key-hash'
,'password-id'
, and'password'
.
-
password
¶ The first WiFi device password. Same as
WifiPasswordRecord().passwords[0]
.
-
other
¶ A list of WiFi attribute (key, value) pairs other than version and device password. Keys are two character strings for standard WiFi attributes, one character strings for subelements within a WFA vendor extension attribute, and three character strings for other vendor extension attributes.
-
nfc.llcp¶
The nfc.llcp module implements the NFC Forum Logical Link Control Protocol (LLCP) specification and provides a socket interface to use the connection-less and connection-mode transport facilities of LLCP.
nfc.llcp.Socket¶
-
class
nfc.llcp.
Socket
(llc, sock_type)¶ Create a new LLCP socket with the given socket type. The socket type should be one of:
nfc.llcp.LOGICAL_DATA_LINK
for best-effort communication using LLCP connection-less PDU exchangenfc.llcp.DATA_LINK_CONNECTION
for reliable communication using LLCP connection-mode PDU exchangenfc.llcp.llc.RAW_ACCESS_POINT
for unregulated LLCP PDU exchange (useful to implement test programs)
-
llc
¶ The
LogicalLinkController
instance to which this socket belongs. This attribute is read-only.
-
resolve
(name)¶ Resolve a service name into an address. This may involve conversation with the remote service discovery component if the name is hasn’t yet been resolved. The return value is the service access point address that the service name is bound to at the remote device. A zero address indicates that the remote device does not know about the service name requested. The return value is None if communication with the peer device got terminated.
-
setsockopt
(option, value)¶ Set the value of the given socket option and return the current value which may have been corrected if it was out of bounds.
-
getsockopt
(option)¶ Return the value of the given socket option.
-
bind
(address=None)¶ Bind the socket to address. The socket must not already be bound. The address may be a service name string, a service access point number, or it may be omitted. If address is a well-known service name the socket will be bound to the corresponding service access point address, otherwise the socket will be bound to the next available service access point address between 16 and 31 (inclusively). If address is a number between 32 and 63 (inclusively) the socket will be bound to that service access point address. If the address argument is omitted the socket will be bound to the next available service access point address between 32 and 63.
-
connect
(address)¶ Connect to a remote socket at address. Address may be a service name string or a service access point number.
-
listen
(backlog)¶ Mark a socket as a socket that will be used to accept incoming connection requests using accept(). The backlog defines the maximum length to which the queue of pending connections for the socket may grow. A backlog of zero disables queuing of connection requests.
-
accept
()¶ Accept a connection. The socket must be bound to an address and listening for connections. The return value is a new socket object usable to send and receive data on the connection.
-
send
(string)¶ Send data to the socket. The socket must be connected to a remote socket. Returns a boolean value that indicates success or failure. Failure to send is generally an indication that the socket or connection was closed.
-
sendto
(string, address)¶ Send data to the socket. The socket should not be connected to a remote socket, since the destination socket is specified by address. Returns a boolean value that indicates success or failure. Failure to send is generally an indication that the socket was closed.
-
recv
()¶ Receive data from the socket. The return value is a string representing the data received. The maximum amount of data that may be returned is determined by the link or connection maximum information unit size.
-
recvfrom
()¶ Receive data from the socket. The return value is a pair (string, address) where string is a string representing the data received and address is the address of the socket sending the data.
-
poll
(event, timeout=None)¶ Wait for a socket event.
-
getsockname
()¶ Obtain the address to which the socket is bound. For an unbound socket the returned value is None.
-
getpeername
()¶ Obtain the address of the peer connected on the socket. For an unconnected socket the returned value is None.
-
close
()¶ Close the socket. All future operations on the socket object will fail. The remote end will receive no more data Sockets are automatically closed when the logical link controller terminates (gracefully or by link disruption). A connection-mode socket will attempt to disconnect the data link connection (if in connected state).
nfc.snep¶
The nfc.snep module implements the NFC Forum Simple NDEF Exchange Protocol (SNEP) specification and provides a server and client class for applications to easily send or receive SNEP messages.
nfc.snep.SnepServer¶
-
class
nfc.snep.
SnepServer
(llc, service_name='urn:nfc:sn:snep', max_acceptable_length=1048576, recv_miu=1984, recv_buf=15)¶ NFC Forum Simple NDEF Exchange Protocol server
-
get
(acceptable_length, ndef_message)¶ Handle Get requests. This method should be overwritten by a subclass of SnepServer to customize it’s behavior. The default implementation simply returns Not Implemented.
-
put
(ndef_message)¶ Handle Put requests. This method should be overwritten by a subclass of SnepServer to customize it’s behavior. The default implementation simply returns Not Implemented.
-
nfc.snep.SnepClient¶
-
class
nfc.snep.
SnepClient
(llc, max_ndef_msg_recv_size=1024)¶ Simple NDEF exchange protocol - client implementation
-
connect
(service_name)¶ Connect to a SNEP server. This needs only be called to connect to a server other than the Default SNEP Server at urn:nfc:sn:snep or if the client wants to send multiple requests with a single connection.
-
close
()¶ Close the data link connection with the SNEP server.
-
get
(ndef_message=None, timeout=1.0)¶ Get an NDEF message from the server. Temporarily connects to the default SNEP server if the client is not yet connected.
-
put
(ndef_message, timeout=1.0)¶ Send an NDEF message to the server. Temporarily connects to the default SNEP server if the client is not yet connected.
-
nfc.handover¶
The nfc.handover module implements the NFC Forum Connection Handover 1.2 protocol as a server and client class that simplify realization of handover selector and requester functionality.
nfc.handover.HandoverServer¶
-
class
nfc.handover.
HandoverServer
(llc, request_size_limit=65536, recv_miu=1984, recv_buf=15)¶ NFC Forum Connection Handover server
-
process_request
(request)¶ Process a handover request message. The request argument is a
nfc.ndef.HandoverRequestMessage
object. The return value must be anfc.ndef.HandoverSelectMessage
object to be sent back to the client.This method should be overwritten by a subclass of
HandoverServer
to customize it’s behavior. The default implementation returns a version1.2
nfc.ndef.HandoverSelectMessage
with no carriers.
-
nfc.handover.HandoverClient¶
-
class
nfc.handover.
HandoverClient
(llc)¶ NFC Forum Connection Handover client
-
connect
(recv_miu=248, recv_buf=2)¶ Connect to the remote handover server if available. Raises
nfc.llcp.ConnectRefused
if the remote device does not have a handover service or the service does not accept any more connections.
-
close
()¶ Disconnect from the remote handover server.
-
send
(message)¶ Send a handover request message to the remote server.
-
recv
(timeout=None)¶ Receive a handover select message from the remote server.
-