tdns

An asynchronous Tornado pycares DNS client wrapper, exporting the full API.

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Installation

tdns is available from the Python Package Index and can be installed by running pip install tdns

Contents

tdns API

The Channel implements a Python class for interacting with the c-ares API using native Tornado asynchronous conventions. For example, to query the MX records for google you could use the following snippet:

from tornado import gen, ioloop, web
import tdns


class RequestHandler(web.RequestHandler):

    @gen.coroutine
    def get(self, *args, **kwargs):
        channel = tdns.Channel(io_loop=ioloop.IOLoop.current())
        response = yield channel.query('google.com', 'MX')

tnds is build on top of the excellent pycares library.

Ares Channel

class tdns.Channel(io_loop=None, **kwargs)[source]

An asynchronous wrapper class for c-ares channels.

cancel()[source]

Cancel any pending query on this channel. All pending requests will raise a AresError with the ARES_ECANCELLED errorno.

Raises:AresError
destroy()[source]

Destroy the channel. All pending requests will raise a AresError with the ARES_EDESTRUCTION errorno.

Raises:AresError
gethostbyaddr(addr)[source]

Retrieves the host information corresponding to a network address.

Parameters:addr (str) – Network address to query
Return type:str
Raises:AresError
gethostbyname(name, family)[source]

Retrieves host information corresponding to a host name from a host database.

Parameters:
  • name (str) – Name to query
  • family (int) – Socket family
Raises:

AresError
getnameinfo(name, port, flags)[source]

Provides protocol-independent name resolution from an address to a host name and from a port number to the service name.

Parameters:
  • name (str) – Name to query
  • port (int) – Port of the service to query
  • flags (int) – Query flags, see the NI flags section
Raises:

AresError
query(name, query_type)[source]

Do a DNS query of the specified type. Available types:

  • tdns.QUERY_TYPE_A
  • tdns.QUERY_TYPE_AAAA
  • tdns.QUERY_TYPE_CNAME
  • tdns.QUERY_TYPE_MX
  • tdns.QUERY_TYPE_NAPTR
  • tdns.QUERY_TYPE_NS
  • tdns.QUERY_TYPE_PTR
  • tdns.QUERY_TYPE_SOA
  • tdns.QUERY_TYPE_SRV
  • tdns.QUERY_TYPE_TXT
Parameters:
  • name (str) – Name to query
  • query_type (int) – Type of query to perform.

Return Types:

  • A and AAAA: ares_query_simple_result, fields:
    • host
    • ttl
  • CNAME: ares_query_cname_result, fields:
    • cname
    • ttl
  • MX: ares_query_mx_result, fields:
    • host
    • priority
    • ttl
  • NAPTR: ares_query_naptr_result, fields:
    • order
    • preference
    • flags
    • service
    • regex
    • replacement
    • ttl
  • NS: ares_query_ns_result, fields:
  • host
  • ttl
  • PTR: ares_query_ptr_result, fields:
    • name
    • ttl
  • SOA: ares_query_soa_result, fields:
    • nsmane
    • hostmaster
    • serial
    • refresh
    • retry
    • expires
    • minttl
    • ttl
  • SRV: ares_query_srv_result, fields:
    • host
    • port
    • priority
    • weight
    • ttl
  • TXT: ares_query_txt_result, fields:
    • text
    • ttl
Raises:AresError
servers

List of nameservers to use for DNS queries

Return type:list
set_local_dev(local_dev)[source]

Set the local ethernet device from which the queries will be sent.

Parameters:local_dev (str) – Network device name
Raises:AresError
Raises:ValueError
set_local_ip(local_ip)[source]

Set the local IPv4 or IPv6 address from which the queries will be sent.

Parameters:local_ip (str) – IP address
Raises:AresError
Raises:ValueError
timeout(max_timeout)[source]

Set the maximum time for which the caller should wait before invoking process_fd to process timeouts. If the max_timeout parameter is specified, it is stored on the channel and the appropriate value is then returned.

Parameters:max_timeout (float) – Maximum timeout
Return type:float
Raises:AresError
Raises:ValueError

Utility Functions

tdns.reverse_address(ip_address)[source]

Returns the reversed representation of an IP address, usually used when doing PTR queries.

Parameters:ip_address (str) – IP address to be reversed
Return type:str

Version History

  • 0.2.0 - released 2016-06-06
    • exported constants from pycares.errno
  • 0.1.0 - released 2016-04-27
    • initial version

Issues

Please report any issues to the Github repo at https://github.com/gmr/tdns/issues

Source

tdns source is available on Github at https://github.com/gmr/tdns

Indices and tables