[pjsip] Resolving A records for domains without SRV records fails

[Alexei Kuznetsov]

Hi,

Here's what I've noticed when started to use DNS SRV features of pjsua- 
lib. If the registrar does not have SRV records, resolving of A record  
fails.

01:39:20.191     resolver.c  Transmitting 37 bytes to NS 0  
(192.168.1.1:53): DNS SRV query for _sip._udp.cubio.net
01:39:22.192     resolver.c  Re-transmitting 37 bytes to NS 0  
(192.168.1.1:53): DNS SRV query for _sip._udp.cubio.net
01:39:24.191     resolver.c  Re-transmitting 37 bytes to NS 0  
(192.168.1.1:53): DNS SRV query for _sip._udp.cubio.net
01:39:26.187 _sip._udp.cubi  DNS SRV resolution failed for  
_sip._udp.cubio.net: DNS "Server failure" (PJLIB_UTIL_EDNS_SERVFAIL)
01:39:26.187 _sip._udp.cubi  DNS SRV resolution failed for  
_sip._udp.cubio.net, trying resolving A record for cubio.net
01:39:26.187 _sip._udp.cubi  DNS A record resolution error for  
'cubio.net'. Err=320046 (No working DNS nameserver  
(PJLIB_UTIL_EDNSNOWORKINGNS))
01:39:26.187  sip_resolve.c  DNS A record resolution failed: No  
working DNS nameserver (PJLIB_UTIL_EDNSNOWORKINGNS)
01:39:26.187    tsx0x8ac064  Failed to send Request msg REGISTER/ 
cseq=15062 (tdta0x8eac00)! err=320046 (No working DNS nameserver  
(PJLIB_UTIL_EDNSNOWORKINGNS))
01:39:26.187    pjsua_acc.c  SIP registration failed, status=503  
(Service Unavailable)


And here are two dig outputs for the same computer and DNS server (it  
can resolve A record for cubio.net).

$ dig _sip._udp.cubio.net srv

; <<>> DiG 9.4.2-P2 <<>> _sip._udp.cubio.net srv
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 42530
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;_sip._udp.cubio.net.		IN	SRV

;; Query time: 4393 msec
;; SERVER: 192.168.1.1#53(192.168.1.1)
;; WHEN: Wed Feb  4 01:46:52 2009
;; MSG SIZE  rcvd: 37


$ dig cubio.net

; <<>> DiG 9.4.2-P2 <<>> cubio.net
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16101
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 3

;; QUESTION SECTION:
;cubio.net.			IN	A

;; ANSWER SECTION:
cubio.net.		3600	IN	A	81.29.134.11

;; AUTHORITY SECTION:
cubio.net.		3600	IN	NS	ns3.cubio.net.
cubio.net.		3600	IN	NS	ns1.cubio.net.
cubio.net.		3600	IN	NS	ns2.cubio.net.

;; ADDITIONAL SECTION:
ns1.cubio.net.		3094	IN	A	81.29.128.1
ns2.cubio.net.		3094	IN	A	81.29.128.2
ns3.cubio.net.		3094	IN	A	81.29.129.125

;; Query time: 58 msec
;; SERVER: 192.168.1.1#53(192.168.1.1)
;; WHEN: Wed Feb  4 01:47:07 2009
;; MSG SIZE  rcvd: 145


Alexei