chan_sip/res_pjsip_t38: Handle a request to negotiate T.38 after it is enabled.

Some T.38 implementations may send another re-invite after the initial
one which adds additional negotiation details (such as the max bitrate).
Currently this will fail when passthrough is being done in chan_sip as we
do nothing if T.38 is already active.

Other handlers of T.38 inside of Asterisk (such as res_fax) handle this
scenario so this change adds support for it to chan_sip and res_pjsip_t38.
If a request to negotiate is received while T.38 is already enabled a
new re-INVITE is sent and negotiation is done again.

ASTERISK-26179 #close

Change-Id: I0298494d3da6df3219bbfa4be9aa04015043145c

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index a5aa6c3d3ce817c8d34d2b26da68feb90e500889..7d4cf8722bcea26df3b111c57a668da2623bdf8b 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -7665,7 +7665,8 @@ static int interpret_t38_parameters(struct sip_pvt *p, const struct ast_control_
                        ast_udptl_set_local_max_ifp(p->udptl, p->t38.our_parms.max_ifp);
                        change_t38_state(p, T38_ENABLED);
                        transmit_response_with_t38_sdp(p, "200 OK", &p->initreq, XMIT_CRITICAL);
-               } else if (p->t38.state != T38_ENABLED) {
+               } else if ((p->t38.state != T38_ENABLED) || ((p->t38.state == T38_ENABLED) &&
+                               (parameters->request_response == AST_T38_REQUEST_NEGOTIATE))) {
                        p->t38.our_parms = *parameters;
                        ast_udptl_set_local_max_ifp(p->udptl, p->t38.our_parms.max_ifp);
                        change_t38_state(p, T38_LOCAL_REINVITE);

diff --git a/res/res_pjsip_t38.c b/res/res_pjsip_t38.c
index 14207d9c056f3b74201556fb8470aef1b70b1bbe..992902af2e3b87a61cdda7fc3162828fe2e4f870 100644 (file)
--- a/res/res_pjsip_t38.c
+++ b/res/res_pjsip_t38.c
@@ -361,7 +361,9 @@ static int t38_interpret_parameters(void *obj)
                        ast_udptl_set_local_max_ifp(session_media->udptl, state->our_parms.max_ifp);
                        t38_change_state(data->session, session_media, state, T38_ENABLED);
                        ast_sip_session_resume_reinvite(data->session);
-               } else if (data->session->t38state != T38_ENABLED) {
+               } else if ((data->session->t38state != T38_ENABLED) ||
+                               ((data->session->t38state == T38_ENABLED) &&
+                                (parameters->request_response == AST_T38_REQUEST_NEGOTIATE))) {
                        if (t38_initialize_session(data->session, session_media)) {
                                break;
                        }