Missing fallback to audio fax feature when T.38 re-INVITE failed

When a T.38 re-INVITE failed with an 488 or 606 answer, we should
fallback to audio fax by send a re-re-INVITE without T.38. The
function is backported from 1.6 asterisk.

(closes issue #16795)
Reported by: vrban

(closes issue #16692)
Reported by: vrban
Patches:
      t38_fallback_to_audio_v3.patch uploaded by vrban (license 756)
Tested by: lmadsen, vrban, haggard

https://reviewboard.asterisk.org/r/514/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@266579 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 84209b0dd8a8f202b7bcdb3691f1f32a413b5cf3..bcc3469a6e47a1e5d178872055b71fed7c997f0e 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -13107,23 +13107,21 @@ static void handle_response_invite(struct sip_pvt *p, int resp, char *rest, stru
        case 606: /* Not Acceptable */
                xmitres = transmit_request(p, SIP_ACK, seqno, XMIT_UNRELIABLE, FALSE);
                if (reinvite && p->udptl) {
-                       /* If this is a T.38 call, we should go back to 
-                          audio. If this is an audio call - something went
-                          terribly wrong since we don't renegotiate codecs,
-                          only IP/port .
-                       */
                        p->t38.state = T38_DISABLED;
                        /* Try to reset RTP timers */
                        ast_rtp_set_rtptimers_onhold(p->rtp);
-                       ast_log(LOG_ERROR, "Got error on T.38 re-invite. Bad configuration. Peer needs to have T.38 disabled.\n");
+                       /* Trigger a reinvite back to audio */
+                       transmit_reinvite_with_sdp(p);
 
-                       /*! \bug Is there any way we can go back to the audio call on both
-                          sides here? 
-                       */
-                       /* While figuring that out, hangup the call */
-                       if (p->owner && !ast_test_flag(req, SIP_PKT_IGNORE))
-                               ast_queue_control(p->owner, AST_CONTROL_CONGESTION);
-                       ast_set_flag(&p->flags[0], SIP_NEEDDESTROY);
+                       if (p->owner && (p->owner->_state == AST_STATE_UP) && (bridgepeer = ast_bridged_channel(p->owner))) { /* if this is a re-invite */
+                               struct sip_pvt *bridgepvt = NULL;
+                               if (bridgepeer->tech == &sip_tech || bridgepeer->tech == &sip_tech_info) {
+                                       bridgepvt = (struct sip_pvt*)(bridgepeer->tech_pvt);
+                                       if (bridgepvt->udptl) {
+                                               sip_handle_t38_reinvite(bridgepeer, p, 0);
+                                       }
+                               }
+                       }
                } else {
                        /* We can't set up this call, so give up */
                        if (p->owner && !ast_test_flag(req, SIP_PKT_IGNORE))
@@ -18980,7 +18978,7 @@ static int sip_handle_t38_reinvite(struct ast_channel *chan, struct sip_pvt *pvt
                p->lastrtprx = p->lastrtptx = time(NULL);
                ast_mutex_unlock(&p->lock);
                return 0;
-       } else {        /* If we are handling sending 200 OK to the other side of the bridge */
+       } else if (pvt->t38.state != T38_DISABLED) {    /* If we are handling sending 200 OK to the other side of the bridge */
                if (ast_test_flag(&p->flags[0], SIP_CAN_REINVITE) && ast_test_flag(&pvt->flags[0], SIP_CAN_REINVITE)) {
                        ast_udptl_get_peer(pvt->udptl, &p->udptlredirip);
                        flag = 1;
@@ -19003,6 +19001,20 @@ static int sip_handle_t38_reinvite(struct ast_channel *chan, struct sip_pvt *pvt
                p->lastrtprx = p->lastrtptx = time(NULL);
                ast_mutex_unlock(&p->lock);
                return 0;
+       } else if (pvt->t38.state == T38_DISABLED) { /* The other side can not talk T.38 with us. We tell it to the the originating T.38 party with a 488 */
+               p->t38.state = T38_DISABLED;
+               if (option_debug > 1) {
+                       ast_log(LOG_DEBUG, "T38 changed state to %d on channel %s\n", pvt->t38.state, pvt->owner ? pvt->owner->name : "<none>");
+                       ast_log(LOG_DEBUG, "T38 changed state to %d on channel %s\n", p->t38.state, chan ? chan->name : "<none>");
+               }
+               transmit_response_reliable(p, "488 Not acceptable here", &p->initreq);
+               p->lastrtprx = p->lastrtptx = time(NULL);
+               ast_mutex_unlock(&p->lock);
+               return 0;
+       } else {
+                       ast_log(LOG_ERROR, "Something went wrong with T.38. State is:%d on channel %s and %d on channel %s\n", pvt->t38.state, pvt->owner ? pvt->owner->name : "<none>", p->t38.state, chan ? chan->name : "<none>");
+                       ast_mutex_unlock(&p->lock);
+                       return 0;
        }
 }