[Dnsmasq-discuss] When multiple CNAMEs are mapped to same domain, then some of the CNAME entries becomes outdated.

Atul Gupta atul14.kumar at gmail.com
Wed Sep 12 04:28:29 BST 2012


I am seeing the following issues with the DNSMASQ:

When multiple CNAMEs are mapped to a single domain then the code seems to
update the domain in the cache multiple times causing the UID to be
updated. When the CNAMEs are requested next time although they are in the
cache, it is marked as outdated (because of the UID mismatch) triggering
the DNSMASQ to forward the query back up to the server.

For example:

Host                                                        Address
                                        Flags     Expires
india.blogs.nytimes.com
                                CF         Fri Sep 14 13:25:24 2012
cityroom.blogs.nytimes.com
                             CF         Fri Sep 14 13:25:17 2012
mediadecoder.blogs.nytimes.com
                       CF         Fri Sep 14 13:25:23 2012
afterdeadline.blogs.nytimes.com
                         CF         Fri Sep 14 13:25:18 2012
opinionator.blogs.nytimes.com
                          CF         Fri Sep 14 13:25:18 2012
well.blogs.nytimes.com
                                  CF         Fri Sep 14 13:25:22 2012
publiceditor.blogs.nytimes.com
                           CF         Fri Sep 14 13:25:18 2012
dealbook.nytimes.com                        dealbook.blogs.nytimes.com
        CF         Fri Sep 14 13:25:10 2012
takingnote.blogs.nytimes.com           blog.nytimes.com
            CF         Fri Sep 14 13:25:24 2012
rendezvous.blogs.nytimes.com
                          CF         Fri Sep 14 13:25:24 2012
tmagazine.blogs.nytimes.com
                           CF         Fri Sep 14 13:25:24 2012
campaignstops.blogs.nytimes.com
                       CF         Fri Sep 14 13:25:18 2012
dealbook.blogs.nytimes.com             blog.nytimes.com
            CF         Fri Sep 14 13:25:10 2012
runway.blogs.nytimes.com
                             CF         Fri Sep 14 13:25:23 2012
lens.blogs.nytimes.com
                                  CF         Fri Sep 14 13:25:11 2012
artsbeat.blogs.nytimes.com
                              CF         Fri Sep 14 13:25:23 2012
krugman.blogs.nytimes.com
                           CF         Fri Sep 14 13:25:24 2012
blog.nytimes.com                                 170.149.168.153
                      4F         Fri Sep 14 13:25:24 2012
blog.nytimes.com
                                      6F   N     Fri Sep 14 13:25:10 2012

In this example when on receiving any one of the CNAME domains query from
the client PC, the DNSMASQ resends the query to the server because the
entry in the cache is deemed as outdated. I fixed the issue by checking the
cache before the "cache_insert" is invoked from the function
"extract_addresses".

Has anyone faced similar issue? Is the fix ok?

Atul.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/attachments/20120912/91ed037a/attachment.html>


More information about the Dnsmasq-discuss mailing list