net/freeswitch-stable/patches/390-t38-reinvite-488-fix.patch

   1 commit 167294ea2649afd0ffedf4520b0f308979c3ca2a
   2 Author: Sebastian Kemper <sebastian_ml@gmx.net>
   3 Date:   Fri Oct 18 18:28:07 2019 +0200
   4
   5     [mod-sofia] Fix reINVITE after T38 is rejected
   6
   7     From FS-11833.
   8
   9     After FS sends a reINVITE to T38 which gets rejected by peer it is no
  10     longer in a state where it can properly answer a reINVITE which requests
  11     a change of the media setup.
  12
  13     1. FS sends INVITE (destination is a fax machine)
  14     2. Call connects with "8 101"
  15     3. FS sends reINVITE to T38
  16     4. T38 rejected (488)
  17     5. FS receives INVITE to "8"
  18     6. FS replies with 200 OK without SDP
  19     7. Call fails
  20
  21     The bug is related to TFLAG_SDP. This flag is set when a media session
  22     is established. And when there's a reINVITE sofia_glue_do_invite() from
  23     sofia_glue.c is called and clears the flag again:
  24
  25     sofia_clear_flag_locked(tech_pvt, TFLAG_SDP);
  26
  27     So when FS sends a reINVITE to T38 the flag gets cleared. But when the
  28     reINVITE is rejected with 488 the flag is not set again. It stays
  29     cleared. So the call continues with the previously negotiated media, fax
  30     passthrough (8 101 in this case), but TFLAG_SDP is not set.
  31
  32     So when FS receives a reINVITE at this point it doesn't see the need to
  33     renegotiate anything, even though it realizes that 2833 DTMF is now off:
  34
  35     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]
  36     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
  37     2019-04-30 16:42:12.478025 [DEBUG] switch_core_media.c:5802 No 2833 in SDP. Disable 2833 dtmf and switch to INFO
  38
  39     When FS doesn't send a reINVITE (fax_enable_t38_request=false) and the
  40     reINVITE to "8" is received, TFLAG_SDP is still set and then FS
  41     understands that it needs to renegotiate and replies with a 200 OK that
  42     includes SDP:
  43
  44     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]
  45     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
  46     2019-04-30 16:41:19.358028 [DEBUG] switch_core_media.c:5802 No 2833 in SDP. Disable 2833 dtmf and switch to INFO
  47     2019-04-30 16:41:19.358028 [DEBUG] sofia.c:8237 skemper was here in line 8232
  48     2019-04-30 16:41:19.358028 [DEBUG] switch_core_media.c:8390 skemper was here in line 8390.
  49     2019-04-30 16:41:19.358028 [DEBUG] switch_core_media.c:8496 Audio params are unchanged for sofia/external/+called_number.
  50     2019-04-30 16:41:19.358028 [DEBUG] sofia.c:8243 Processing updated SDP
  51
  52     This fixes the state problem after a rejected T38 reINVITE by setting
  53     TFLAG_SDP.
  54
  55     Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>
  56
  57 --- a/src/mod/endpoints/mod_sofia/sofia.c
  58 +++ b/src/mod/endpoints/mod_sofia/sofia.c
  59 @@ -6501,6 +6501,7 @@ static void sofia_handle_sip_r_invite(sw
  60                         switch_channel_clear_app_flag_key("T38", tech_pvt->channel, CF_APP_T38_REQ);
  61                         switch_channel_set_app_flag_key("T38", tech_pvt->channel, CF_APP_T38_FAIL);
  62                         switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_DEBUG, "%s T38 invite failed\n", switch_channel_get_name(tech_pvt->channel));
  63 +                       sofia_set_flag(tech_pvt, TFLAG_SDP);
  64                 }
  65
  66