[pjsip] DNS bug

Klaus Darilion klaus.mailinglists at pernau.at
Fri Aug 28 04:05:23 EDT 2009


Hi!

There is problem in pjproject handling SERVFAIL responses from the 
nameserver. Obviously, if a nameserver responds several times with 
SERVFAIL, the NS get marked as bad. This is wrong, as the nameserver 
might be good - it it is just an upstream error.

e.g. take a look at the attached 2 traces. I started pjsua to register a 
at a SIP proxy. In one case, the used STUN server has a broken domain 
configuration, thus the resolver responds with SERVFAIL. This marks the 
nameserver as broken and the following DNS lookup for the SIP domain is 
not even tried, as the nameserver is tagged as broken!

Conclusion: A nameserver must not be tagged as "nonworking" just because 
of received SERVFAIL - as this might be caused by an upstream problem.

regards
Klaus
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