Accept additional T.38 reinvites after an initial one has been handled.

Discussion of this subject has yielded that it is not actually acceptable to change
T.38 parameters after the initial reinvite but declining is harsh and can cause the
fax to fail when it may be possible to allow it to continue. This patch changes things
so that additional T.38 reinvites are accepted but parameter changes ignored. This gives
the fax a fighting chance.

(closes issue #15610)
Reported by: huangtx2009

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@210817 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 78b42c8219ff0fda602f4694dc5f5e30c3d54c04..5b7fa593b4b2ef405122fa3ed18a173142b201c1 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -8463,108 +8463,110 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
        }
        
        if (udptlportno != -1) {
-               int found = 0, x;
+               if (p->t38.state != T38_ENABLED) {
+                       int found = 0, x;
                
-               old = 0;
-               memset(&p->t38.their_parms, 0, sizeof(p->t38.their_parms));
+                       old = 0;
+                       memset(&p->t38.their_parms, 0, sizeof(p->t38.their_parms));
                
-               /* Scan trough the a= lines for T38 attributes and set apropriate fileds */
-               iterator = req->sdp_start;
-               while ((a = get_sdp_iterate(&iterator, req, "a"))[0] != '\0') {
-                       if ((sscanf(a, "T38FaxMaxBuffer:%d", &x) == 1)) {
-                               found = 1;
-                               ast_debug(3, "MaxBufferSize:%d\n", x);
-                       } else if ((sscanf(a, "T38MaxBitRate:%d", &x) == 1) || (sscanf(a, "T38FaxMaxRate:%d", &x) == 1)) {
-                               found = 1;
-                               ast_debug(3, "T38MaxBitRate: %d\n", x);
-                               switch (x) {
-                               case 14400:
-                                       p->t38.their_parms.rate = AST_T38_RATE_14400;
-                                       break;
-                               case 12000:
-                                       p->t38.their_parms.rate = AST_T38_RATE_12000;
-                                       break;
-                               case 9600:
-                                       p->t38.their_parms.rate = AST_T38_RATE_9600;
-                                       break;
-                               case 7200:
-                                       p->t38.their_parms.rate = AST_T38_RATE_7200;
-                                       break;
-                               case 4800:
-                                       p->t38.their_parms.rate = AST_T38_RATE_4800;
-                                       break;
-                               case 2400:
-                                       p->t38.their_parms.rate = AST_T38_RATE_2400;
-                                       break;
-                               }
-                       } else if ((sscanf(a, "T38FaxVersion:%d", &x) == 1)) {
-                               found = 1;
-                               ast_debug(3, "FaxVersion: %d\n", x);
-                               p->t38.their_parms.version = x;
-                       } else if ((sscanf(a, "T38FaxMaxDatagram:%d", &x) == 1) || (sscanf(a, "T38MaxDatagram:%d", &x) == 1)) {
-                               found = 1;
-                               ast_debug(3, "FaxMaxDatagram: %d\n", x);
-                               ast_udptl_set_far_max_datagram(p->udptl, x);
-                       } else if ((strncmp(a, "T38FaxFillBitRemoval", 20) == 0)) {
-                               found = 1;
-                               if (sscanf(a, "T38FaxFillBitRemoval:%d", &x) == 1) {
-                                       ast_debug(3, "FillBitRemoval: %d\n", x);
-                                       if (x == 1) {
+                       /* Scan trough the a= lines for T38 attributes and set apropriate fileds */
+                       iterator = req->sdp_start;
+                       while ((a = get_sdp_iterate(&iterator, req, "a"))[0] != '\0') {
+                               if ((sscanf(a, "T38FaxMaxBuffer:%d", &x) == 1)) {
+                                       found = 1;
+                                       ast_debug(3, "MaxBufferSize:%d\n", x);
+                               } else if ((sscanf(a, "T38MaxBitRate:%d", &x) == 1) || (sscanf(a, "T38FaxMaxRate:%d", &x) == 1)) {
+                                       found = 1;
+                                       ast_debug(3, "T38MaxBitRate: %d\n", x);
+                                       switch (x) {
+                                       case 14400:
+                                               p->t38.their_parms.rate = AST_T38_RATE_14400;
+                                               break;
+                                       case 12000:
+                                               p->t38.their_parms.rate = AST_T38_RATE_12000;
+                                               break;
+                                       case 9600:
+                                               p->t38.their_parms.rate = AST_T38_RATE_9600;
+                                               break;
+                                       case 7200:
+                                               p->t38.their_parms.rate = AST_T38_RATE_7200;
+                                               break;
+                                       case 4800:
+                                               p->t38.their_parms.rate = AST_T38_RATE_4800;
+                                               break;
+                                       case 2400:
+                                               p->t38.their_parms.rate = AST_T38_RATE_2400;
+                                               break;
+                                       }
+                               } else if ((sscanf(a, "T38FaxVersion:%d", &x) == 1)) {
+                                       found = 1;
+                                       ast_debug(3, "FaxVersion: %d\n", x);
+                                       p->t38.their_parms.version = x;
+                               } else if ((sscanf(a, "T38FaxMaxDatagram:%d", &x) == 1) || (sscanf(a, "T38MaxDatagram:%d", &x) == 1)) {
+                                       found = 1;
+                                       ast_debug(3, "FaxMaxDatagram: %d\n", x);
+                                       ast_udptl_set_far_max_datagram(p->udptl, x);
+                               } else if ((strncmp(a, "T38FaxFillBitRemoval", 20) == 0)) {
+                                       found = 1;
+                                       if (sscanf(a, "T38FaxFillBitRemoval:%d", &x) == 1) {
+                                               ast_debug(3, "FillBitRemoval: %d\n", x);
+                                               if (x == 1) {
+                                                       p->t38.their_parms.fill_bit_removal = TRUE;
+                                               }
+                                       } else {
+                                               ast_debug(3, "FillBitRemoval\n");
                                                p->t38.their_parms.fill_bit_removal = TRUE;
                                        }
-                               } else {
-                                       ast_debug(3, "FillBitRemoval\n");
-                                       p->t38.their_parms.fill_bit_removal = TRUE;
-                               }
-                       } else if ((strncmp(a, "T38FaxTranscodingMMR", 20) == 0)) {
-                               found = 1;
-                               if (sscanf(a, "T38FaxTranscodingMMR:%d", &x) == 1) {
-                                       ast_debug(3, "Transcoding MMR: %d\n", x);
-                                       if (x == 1) {
+                               } else if ((strncmp(a, "T38FaxTranscodingMMR", 20) == 0)) {
+                                       found = 1;
+                                       if (sscanf(a, "T38FaxTranscodingMMR:%d", &x) == 1) {
+                                               ast_debug(3, "Transcoding MMR: %d\n", x);
+                                               if (x == 1) {
+                                                       p->t38.their_parms.transcoding_mmr = TRUE;
+                                               }
+                                       } else {
+                                               ast_debug(3, "Transcoding MMR\n");
                                                p->t38.their_parms.transcoding_mmr = TRUE;
                                        }
-                               } else {
-                                       ast_debug(3, "Transcoding MMR\n");
-                                       p->t38.their_parms.transcoding_mmr = TRUE;
-                               }
-                       } else if ((strncmp(a, "T38FaxTranscodingJBIG", 21) == 0)) {
-                               found = 1;
-                               if (sscanf(a, "T38FaxTranscodingJBIG:%d", &x) == 1) {
-                                       ast_debug(3, "Transcoding JBIG: %d\n", x);
-                                       if (x == 1) {
+                               } else if ((strncmp(a, "T38FaxTranscodingJBIG", 21) == 0)) {
+                                       found = 1;
+                                       if (sscanf(a, "T38FaxTranscodingJBIG:%d", &x) == 1) {
+                                               ast_debug(3, "Transcoding JBIG: %d\n", x);
+                                               if (x == 1) {
+                                                       p->t38.their_parms.transcoding_jbig = TRUE;
+                                               }
+                                       } else {
+                                               ast_debug(3, "Transcoding JBIG\n");
                                                p->t38.their_parms.transcoding_jbig = TRUE;
                                        }
-                               } else {
-                                       ast_debug(3, "Transcoding JBIG\n");
-                                       p->t38.their_parms.transcoding_jbig = TRUE;
-                               }
-                       } else if ((sscanf(a, "T38FaxRateManagement:%255s", s) == 1)) {
-                               found = 1;
-                               ast_debug(3, "RateManagement: %s\n", s);
-                               if (!strcasecmp(s, "localTCF"))
-                                       p->t38.their_parms.rate_management = AST_T38_RATE_MANAGEMENT_LOCAL_TCF;
-                               else if (!strcasecmp(s, "transferredTCF"))
-                                       p->t38.their_parms.rate_management = AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF;
-                       } else if ((sscanf(a, "T38FaxUdpEC:%255s", s) == 1)) {
-                               found = 1;
-                               ast_debug(3, "UDP EC: %s\n", s);
-                               if (!strcasecmp(s, "t38UDPRedundancy")) {
-                                       ast_udptl_set_error_correction_scheme(p->udptl, UDPTL_ERROR_CORRECTION_REDUNDANCY);
-                               } else if (!strcasecmp(s, "t38UDPFEC")) {
-                                       ast_udptl_set_error_correction_scheme(p->udptl, UDPTL_ERROR_CORRECTION_FEC);
-                               } else {
-                                       ast_udptl_set_error_correction_scheme(p->udptl, UDPTL_ERROR_CORRECTION_NONE);
+                               } else if ((sscanf(a, "T38FaxRateManagement:%255s", s) == 1)) {
+                                       found = 1;
+                                       ast_debug(3, "RateManagement: %s\n", s);
+                                       if (!strcasecmp(s, "localTCF"))
+                                               p->t38.their_parms.rate_management = AST_T38_RATE_MANAGEMENT_LOCAL_TCF;
+                                       else if (!strcasecmp(s, "transferredTCF"))
+                                               p->t38.their_parms.rate_management = AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF;
+                               } else if ((sscanf(a, "T38FaxUdpEC:%255s", s) == 1)) {
+                                       found = 1;
+                                       ast_debug(3, "UDP EC: %s\n", s);
+                                       if (!strcasecmp(s, "t38UDPRedundancy")) {
+                                               ast_udptl_set_error_correction_scheme(p->udptl, UDPTL_ERROR_CORRECTION_REDUNDANCY);
+                                       } else if (!strcasecmp(s, "t38UDPFEC")) {
+                                               ast_udptl_set_error_correction_scheme(p->udptl, UDPTL_ERROR_CORRECTION_FEC);
+                                       } else {
+                                               ast_udptl_set_error_correction_scheme(p->udptl, UDPTL_ERROR_CORRECTION_NONE);
+                                       }
                                }
                        }
-               }
 
-               /* Remote party offers T38, we need to update state */
-               if ((t38action == SDP_T38_ACCEPT) &&
-                   (p->t38.state == T38_LOCAL_REINVITE)) {
-                       change_t38_state(p, T38_ENABLED);
-               } else if ((t38action == SDP_T38_INITIATE) &&
-                          p->owner && p->lastinvite) {
-                       change_t38_state(p, T38_PEER_REINVITE); /* T38 Offered in re-invite from remote party */
+                       /* Remote party offers T38, we need to update state */
+                       if ((t38action == SDP_T38_ACCEPT) &&
+                           (p->t38.state == T38_LOCAL_REINVITE)) {
+                               change_t38_state(p, T38_ENABLED);
+                       } else if ((t38action == SDP_T38_INITIATE) &&
+                                  p->owner && p->lastinvite) {
+                               change_t38_state(p, T38_PEER_REINVITE); /* T38 Offered in re-invite from remote party */
+                       }
                }
        } else {
                change_t38_state(p, T38_DISABLED);