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. With this release we are moving towards a design that is more consistent with Python object design.
Dependencies¶
This version of getdns has been built and tested against Python 2.7. We also expect these other prerequisites to be installed:
- libgetdns, version 0.1.2 or later
- libldns, version 1.6.11 or later
- libunbound, version 1.4.16 or later
- libexpat (needed for unbound)
- libidn version 1
- libevent version 2.0.21 stable
n.b.: libgetdns must be built with the libevent extension, as follows:
./configure --with-libevent
This release has been tested against libgetdns 0.1.5.
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
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.GETDNS_EXTENSION_TRUE }
results = ctx.address(name=sys.argv[1], extensions=extensions)
if results["status"] == getdns.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)
if results["status"] == getdns.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 = {
"GETDNS_DNSSEC_SECURE" : 400,
"GETDNS_DNSSEC_BOGUS" : 401,
"GETDNS_DNSSEC_INDETERINATE" : 402,
"GETDNS_DNSSEC_INSECURE" : 403,
"GETDNS_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.GETDNS_EXTENSION_TRUE,
"dnssec_return_status" : getdns.GETDNS_EXTENSION_TRUE }
results = ctx.address(name=sys.argv[1], extensions=extensions)
if results["status"] == getdns.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.GETDNS_RESPSTATUS_NO_NAME:
print "{0} not found".format(sys.argv[1])
if __name__ == "__main__":
main()
Known issues¶
- “userarg” currently only accepts a string. This will be changed in a future release, to take arbitrary data types
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