[Freeipa-devel] [PATCH] 260 Replace DNS client based on acutil with python-dns

[Petr Viktorin]

On 05/16/2012 09:44 AM, Martin Kosek wrote:
> On Tue, 2012-05-15 at 14:02 +0200, Petr Viktorin wrote:
>> >  On 05/11/2012 06:52 PM, Martin Kosek wrote:
>>> >  >  python-dns is very feature-rich and it can help us a lot with our DNS
>>> >  >  related code. This patch does the first step, i.e. replaces acutil use
>>> >  >  with python-dns, which is more convenient to use as you will see in the
>>> >  >  patch. More integration will follow in the future.
>>> >  >
>>> >  >  I send this patch rather early, so that I can get responses to this
>>> >  >  patch early and also so that we are able to catch issues in a safe
>>> >  >  distance from the next release.
>> >
>>> >  >  ---
>>> >  >  IPA client and server tool set used authconfig acutil module to
>>> >  >  for client DNS operations. This is not optimal DNS interface for
>>> >  >  several reasons:
>>> >  >  - does not provide native Python object oriented interface
>>> >  >      but but rather C-like interface based on functions and
>>> >  >      structures which is not easy to use and extend
>>> >  >  - acutil is not meant to be used by third parties besides
>>> >  >      authconfig and thus can break without notice
>>> >  >
>>> >  >  Replace the acutil with python-dns package which has a feature rich
>>> >  >  interface for dealing with all different aspects of DNS including
>>> >  >  DNSSEC. The main target of this patch is to replace all uses of
>>> >  >  acutil DNS library with a use python-dns. In most cases, even
>>> >  >  though the larger parts of the code are changed, the actual
>>> >  >  functionality is changed only in the following cases:
>>> >  >  - redundant DNS checks were removed from verify_fqdn function
>>> >  >      in installutils to make the whole DNS check simpler and
>>> >  >      less error-prone. Logging was improves for the remaining
>>> >  >      checks
>>> >  >  - improved logging for ipa-client-install DNS discovery
>>> >  >
>>> >  >  https://fedorahosted.org/freeipa/ticket/2730
>> >

[...]

> Fixed.
>
> Martin

I've been testing the patches in various setups and haven't found a 
regression so far. ACK on 261, for 260 I have a comment below.


> diff --git a/ipa-client/ipaclient/ipadiscovery.py b/ipa-client/ipaclient/ipadiscovery.py
> index 86bef28b2d7fdfc8111b493bddec7ac6888f021a..1889d1918c01fe0c80a3d56b9a7ef304c5a7d97c 100644
> --- a/ipa-client/ipaclient/ipadiscovery.py
> +++ b/ipa-client/ipaclient/ipadiscovery.py
> @@ -310,84 +313,74 @@ class IPADiscovery:
>               os.rmdir(temp_ca_dir)
>
>
> -    def ipadnssearchldap(self, tdomain):
> -        servers = ""
> -        rserver = ""
> +    def ipadns_search_srv(self, domain, srv_record_name, default_port,
> +                          get_first=True):
> +        """
> +        Search for SRV records in given domain. When no record is found,
> +        en empty string is returned
>
> -        qname = "_ldap._tcp."+tdomain
> -        # terminate the name
> -        if not qname.endswith("."):
> -            qname += "."
> -        results = ipapython.dnsclient.query(qname, ipapython.dnsclient.DNS_C_IN, ipapython.dnsclient.DNS_T_SRV)
> +        :param domain: Search domain name
> +        :param srv_record_name: SRV record name, e.g. "_ldap._tcp"
> +        :param default_port: When default_port is not None, it is being
> +                    checked with the port in SRV record and if they don't
> +                    match, the port from SRV record is appended to
> +                    found hostname in this format: "hostname:port"
> +        :param get_first: break on first find, otherwise multiple finds
> +                    separated by ":" may be returned

They are separated by ",".
In the calling code, for splitting a comma-separated string it is better 
to use servers.split(',') than ipautil.parse_items(servers). Or, return 
a list directly from here.

-- 
Petr³