strans/accept: fix cancel/rejection #423

maximilianfridrich · 2022-07-06T16:09:51Z

This PR fixes an issue introduced with PR #419. It prevented a call from being canceled during early media/ringing if a 100rel/PRACK exchange happened in the transaction.

Without the changes in src/sipsess/accept.c, the SIP 4xx responses were being retransmitted until T2 fired even though the 4xx responses were being ACKed. I haven't been able to figure out why that happened, maybe there is a better solution than the one I propose in this PR.

Update: The server transactions are now being correctly used. The changes in this PR provide a clean solution.

src/sipsess/accept.c

src/sip/strans.c

maximilianfridrich · 2022-07-07T09:51:51Z

I have tried to find a different approach by not resetting the server transaction when a response code >=200 is received to a PRACK message (in sip/strans.c:sip_strans_reply:358). That simplified some of the changes introduced with PR #419 but led to multiple memory leaks that I was not able fix easily.

The solution was to not re-use the server transaction of the initial INVITE when replying to a PRACK. The function sip_treplyf allocates a new temporary strans if no strans is passed to it. This way, the server transaction of the initial INVITE is not erroneously freed.

src/sipsess/accept.c

src/sipsess/reply.c

In sipsess_reply_2xx, the reply is sent using a server transaction which sets the st to NULL when replying with scode >=200. This is problematic when sending 2xx responses to PRACKs after which sess->st was NULL. Now, st is not passed to sip_treplyf if the request was PRACK, so st is not set to NULL.

src/sipsess/accept.c

src/sipsess/reply.c

strans/accept: fix cancel/rejection

5147fea