[Users] DNS queries and TLS

[Papadopoulos Georgios]

Hello,
 
I am having some performance issues with Openser and I tend to believe
they are related with DNS. So I am trying to figure out when and why
Openser is doing DNS queries. Doing ngrep on port 53 I realized that
right before sending out the "100 trying -- your call is important to
us" message, Openser is doing a reverse DNS lookup for the IP where the
INVITE came from. So the sequence is something like:
client                            Openser                   DNS
   |---INVITE------------------------>|
   |<---407 Proxy Auth Reqd---|
   |---ACK--------------------------->|
   |---INVITE------------------------>|
                                           |---client IP?-------->|
                                           |<-------------------------|
   |<--------------------100 trying---|
 
 
I am using Openser-1.1.0-notls and in my script I have 
dns=no
rev_dns=no
So first question is whether this DNS query is necessary and how I could
avoid it.
 
What is furthermore confusing is that I have a test system with the same
Openser version and same script, where this DNS query is not happening.
Looking into the production system I found the following:
ser2:/usr/local/openser-1.1.0-notls/sbin# ldd openser
        linux-gate.so.1 =>  (0xffffe000)
        libdl.so.2 => /lib/tls/libdl.so.2 (0x55571000)
        libresolv.so.2 => /lib/tls/libresolv.so.2 (0x55574000)
        libc.so.6 => /lib/tls/libc.so.6 (0x55587000)
        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x55555000)
whereas the test system shows:
sertest:/usr/local/openser-1.1.0-notls/sbin# ldd openser
        libdl.so.2 => /lib/libdl.so.2 (0x7002c000)
        libresolv.so.2 => /lib/libresolv.so.2 (0x70040000)
        libc.so.6 => /lib/libc.so.6 (0x70064000)
        /lib/ld-linux.so.2 (0x70000000)

So the two systems link to different libresolv.so libraries. Is the
tls/libresolve.so that is responsible for the DNS query? Given that in
both cases I am using the notls version of Openser 1.1, why is there a
difference between the two? 
 
thank you for any help
 
George
 

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