From 167294ea2649afd0ffedf4520b0f308979c3ca2a Mon Sep 17 00:00:00 2001 From: Sebastian Kemper Date: Fri, 18 Oct 2019 18:28:07 +0200 Subject: [PATCH] [mod-sofia] Fix reINVITE after T38 is rejected From FS-11833. After FS sends a reINVITE to T38 which gets rejected by peer it is no longer in a state where it can properly answer a reINVITE which requests a change of the media setup. 1. FS sends INVITE (destination is a fax machine) 2. Call connects with "8 101" 3. FS sends reINVITE to T38 4. T38 rejected (488) 5. FS receives INVITE to "8" 6. FS replies with 200 OK without SDP 7. Call fails The bug is related to TFLAG_SDP. This flag is set when a media session is established. And when there's a reINVITE sofia_glue_do_invite() from sofia_glue.c is called and clears the flag again: sofia_clear_flag_locked(tech_pvt, TFLAG_SDP); So when FS sends a reINVITE to T38 the flag gets cleared. But when the reINVITE is rejected with 488 the flag is not set again. It stays cleared. So the call continues with the previously negotiated media, fax passthrough (8 101 in this case), but TFLAG_SDP is not set. So when FS receives a reINVITE at this point it doesn't see the need to renegotiate anything, even though it realizes that 2833 DTMF is now off: 2019-04-30 16:42:12.478025 [DEBUG] switch_core_media.c:5478 Audio Codec Compare [PCMA:8:8000:20:64000:1]/[PCMA:8:8000:20:64000:1] 2019-04-30 16:42:12.478025 [DEBUG] switch_core_media.c:5533 Audio Codec Compare [PCMA:8:8000:20:64000:1] ++++ is saved as a match 2019-04-30 16:42:12.478025 [DEBUG] switch_core_media.c:5802 No 2833 in SDP. Disable 2833 dtmf and switch to INFO When FS doesn't send a reINVITE (fax_enable_t38_request=false) and the reINVITE to "8" is received, TFLAG_SDP is still set and then FS understands that it needs to renegotiate and replies with a 200 OK that includes SDP: 2019-04-30 16:41:19.358028 [DEBUG] switch_core_media.c:5478 Audio Codec Compare [PCMA:8:8000:20:64000:1]/[PCMA:8:8000:20:64000:1] 2019-04-30 16:41:19.358028 [DEBUG] switch_core_media.c:5533 Audio Codec Compare [PCMA:8:8000:20:64000:1] ++++ is saved as a match 2019-04-30 16:41:19.358028 [DEBUG] switch_core_media.c:5802 No 2833 in SDP. Disable 2833 dtmf and switch to INFO 2019-04-30 16:41:19.358028 [DEBUG] sofia.c:8237 skemper was here in line 8232 2019-04-30 16:41:19.358028 [DEBUG] switch_core_media.c:8390 skemper was here in line 8390. 2019-04-30 16:41:19.358028 [DEBUG] switch_core_media.c:8496 Audio params are unchanged for sofia/external/+called_number. 2019-04-30 16:41:19.358028 [DEBUG] sofia.c:8243 Processing updated SDP This fixes the state problem after a rejected T38 reINVITE by setting TFLAG_SDP. Signed-off-by: Sebastian Kemper --- src/mod/endpoints/mod_sofia/sofia.c | 1 + 1 file changed, 1 insertion(+) diff --git a/src/mod/endpoints/mod_sofia/sofia.c b/src/mod/endpoints/mod_sofia/sofia.c index 38cf504f83..18b3e03b75 100644 --- a/src/mod/endpoints/mod_sofia/sofia.c +++ b/src/mod/endpoints/mod_sofia/sofia.c @@ -6507,6 +6507,7 @@ static void sofia_handle_sip_r_invite(switch_core_session_t *session, int status switch_channel_clear_app_flag_key("T38", tech_pvt->channel, CF_APP_T38_REQ); switch_channel_set_app_flag_key("T38", tech_pvt->channel, CF_APP_T38_FAIL); switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_DEBUG, "%s T38 invite failed\n", switch_channel_get_name(tech_pvt->channel)); + sofia_set_flag(tech_pvt, TFLAG_SDP); }