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getdns: Python bindings for getdns

"getdns" is an implementation of Python language bindings for the getdns API. getdns is a modern, asynchronous DNS API that simplifies access to advanced DNS features, including DNSSEC. The API specification was developed by Paul Hoffman. getdns is built on top of the getdns implementation developed as a joint project between Verisign Labs and NLnet Labs.

We have tried to keep this interface as Pythonic as we can while staying true to the getdns architecture, including trying to maintain consistency with Python object design.

Dependencies

This version of getdns has been built and tested against Python 2.7 and Python 3.4. We also expect these other prerequisites to be installed:

This release has been tested against libgetdns 0.9.0.

Building

The code repository for getdns is available at: https://github.com/getdnsapi/getdns-python-bindings. If you are building from source you will need the Python development package for Python 2.7. On Linux systems this is typically something along the lines of "python-dev" or "python2.7-dev", available through your package system. On Mac OS we are building against the python.org release, available in source form here.

For the actual build, we are using the standard Python distutils. To build and install:

python setup.py build
python setup.py install

If you have installed getdns libraries and headers in other than the default location, build the Python bindings using the --with-getdns argument to setup.py, providing the getdns root directory as an argument. (Note that there should be a space between --with-getdns and the directory). For example,

python setup.py build --with-getdns ~/build

if you installed getdns into your home/build directory.

We've added optional support for draft-ietf-dnsop-cookies. It is implemented as a getdns extension (see below). It is not built by default. To enable it, you must build libgetdns with cookies support and add the --with-edns-cookies to the Python module build (i.e. python setup.py build --with-edns-cookies).

Using getdns

Contexts

All getdns queries happen within a resolution context, and among the first tasks you'll need to do before issuing a query is to acquire a Context object. A context is an opaque object with attributes describing the environment within which the query and replies will take place, including elements such as DNSSEC validation, whether the resolution should be performed as a recursive resolver or a stub resolver, and so on. Individual Context attributes may be examined directly, and the overall state of a given context can be queried with the Context.get_api_information() method.

See section 8 of the API specification

Examples

In this example, we do a simple address lookup and dump the results to the screen:

import getdns, pprint, sys

def main():
    if len(sys.argv) != 2:
        print "Usage: {0} hostname".format(sys.argv[0])
        sys.exit(1)

    ctx = getdns.Context()
    extensions = { "return_both_v4_and_v6" :
    getdns.EXTENSION_TRUE }
    results = ctx.address(name=sys.argv[1],
    extensions=extensions)
    if results.status == getdns.RESPSTATUS_GOOD:
        sys.stdout.write("Addresses: ")

        for addr in results.just_address_answers:
            print " {0}".format(addr["address_data"])
        sys.stdout.write("\n\n")
        print "Entire results tree: "
        pprint.pprint(results.replies_tree)
    if results.status == getdns.RESPSTATUS_NO_NAME:
        print "{0} not found".format(sys.argv[1])

if __name__ == "__main__":
    main()

In this example, we do a DNSSEC query and check the response:

import getdns, sys

dnssec_status = {
    "DNSSEC_SECURE" : 400,
    "DNSSEC_BOGUS" : 401,
    "DNSSEC_INDETERINATE" : 402,
    "DNSSEC_INSECURE" : 403,
    "DNSSEC_NOT_PERFORMED" : 404
}


def dnssec_message(value):
    for message in dnssec_status.keys():
        if dnssec_status[message] == value:
            return message

def main():
    if len(sys.argv) != 2:
        print "Usage: {0} hostname".format(sys.argv[0])
        sys.exit(1)

    ctx = getdns.Context()
    extensions = { "return_both_v4_and_v6" :
    getdns.EXTENSION_TRUE,
                   "dnssec_return_status" :
                   getdns.EXTENSION_TRUE }
    results = ctx.address(name=sys.argv[1],
    extensions=extensions)
    if results.status == getdns.RESPSTATUS_GOOD:
        sys.stdout.write("Addresses: ")
        for addr in results.just_address_answers:
            print " {0}".format(addr["address_data"])
        sys.stdout.write("\n")

        for result in results.replies_tree:
            if "dnssec_status" in result.keys():
                print "{0}: dnssec_status:
                {1}".format(result["canonical_name"],
                                                       dnssec_message(result["dnssec_status"]))

    if results.status == getdns.RESPSTATUS_NO_NAME:
        print "{0} not found".format(sys.argv[1])


if __name__ == "__main__":
    main()

Module-level attributes and methods

.. py:attribute:: __version__

   The ``getdns.__version__`` attribute contains the version
   string for the Python getdns module.  Please note that
   this is independent of the version of the underlying
   getdns library, which may be retrieved through attributes
   associated with a Context.

.. py:method:: get_errorstr_by_id()

   Returns a human-friendly string representation of an
   error ID.

.. py:method:: ulabel_to_alabel()

   Converts a ulabel to an alabel.  Takes one argument (the
   ulabel)

.. py:method:: alabel_to_ulabel()

   Converts an alabel to a ulabel.  Takes one argument (the
   alabel)

.. py:method:: root_trust_anchor()

   Returns the default root trust anchor for DNSSEC.

Known issues

  • "userarg" currently only accepts a string. This will be changed in a future release, to take arbitrary data types

Contents:

.. toctree::
   :maxdepth: 1

   functions
   response
   exceptions


Indices and tables