Via: branch in non-200 ACK differs from Via: branch in INVITE.

[whosgonna]

When receiving a non 200 reply for an INVITE sipexer sends a response, but the branch parameter of the via header does not match the branch parameter of the INVITE.

Given this minimal Kamailio config:

#!KAMAILIO

loadmodule "tm.so"
loadmodule "sl.so"
loadmodule "pv.so"

request_route {
    if ( $rm == "ACK" ) {
        if( !t_check_trans() ) {
            exit;
        }
    }
    t_newtran();
    t_reply("404","Not Found");
}

Sending an Invite from sipexer (where kamailio resolves to the host running the kamailio.cfg above):

sipexer -invite kamailio

Has Kamailio repeatedly sending the 404 reply after sipexer sends an ACK. This appears to be due to the ACK's via: header having a different branch than the INVITE.

INVITE (minus SDP):

INVITE sip:kamailio:5060 SIP/2.0
Via: SIP/2.0/UDP 172.31.0.4:56595;rport;branch=z9hG4bKSG.f7f686a3-ce6d-45a1-95a7-42652740d210
From: <sip:alice@localhost>;tag=9dc18f12-c779-4b0e-b30e-681d0526c72e
To: <sip:bob@localhost>
Call-ID: 0418f8d8-d472-43ab-9dc2-786129278a1c
CSeq: 481768 INVITE
Date: Fri, 01 Apr 2022 16:30:13 CDT
User-Agent: SIPExer v1.0.0
Content-Length: 210
Content-Type: application/sdp

ACK:

ACK sip:kamailio:5060 SIP/2.0
Via: SIP/2.0/UDP 172.31.0.4:56595;rport;branch=z9hG4bKSG.cda7e72d-892c-4bee-ad36-cec0734d8c59
From: <sip:alice@localhost>;tag=9dc18f12-c779-4b0e-b30e-681d0526c72e
To: <sip:bob@localhost>;tag=a6a1c5f60faecf035a1ae5b6e96e979a-f254
Call-ID: 0418f8d8-d472-43ab-9dc2-786129278a1c
CSeq: 481768 ACK
Content-Length: 0

Call flow:

             172.31.0.4:56595              172.31.0.3:5060  
          ──────────┬─────────          ──────────┬─────────
  16:30:13.498783   │           INVITE            │ 
        +0.000956   │ ──────────────────────────> │ 
  16:30:13.499739   │        404 Not Found        │ 
        +0.000530   │ <────────────────────────── │ 
  16:30:13.500269   │             ACK             │ 
        +0.447913   │ ──────────────────────────> │ 
  16:30:13.948182   │        404 Not Found        │ 
        +0.999823   │ <<<──────────────────────── │ 
  16:30:14.948005   │        404 Not Found        │ 
        +2.000091   │ <<<──────────────────────── │ 
  16:30:16.948096   │        404 Not Found        │        
                    │ <<<──────────────────────── │

[miconda]

Thanks for testing and reporting back! Somehow I failed to notice the issue report so far.

I just pushed a commit for it, but I had no chance to test it myself yet. If you have time to test soon, let me know if works ok.

[whosgonna]

Sorry for the delayed response here. Yes, that seems to correct it. Note: I'm not sure what your workflow for updating the pre-compiled binary is, but it's still the older version. I don't think that's really a problem. I just didn't think about it at first and my first test just grabbed the binary. :)

Closing the issue.

[miconda]

Thanks for testing and reporting back. Binaries are generated on a release, not on commit. I was waiting to see if it fixes and I will trigger a new release.