Change in libosmo-abis[master]: osmo_ortp: Fix seqno reset to 0 upon ssrc_changed

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pespin gerrit-no-reply at
Mon Jul 26 13:02:47 UTC 2021

pespin has submitted this change. ( )

Change subject: osmo_ortp: Fix seqno reset to 0 upon ssrc_changed

osmo_ortp: Fix seqno reset to 0 upon ssrc_changed

It was spotted in an osmo-mgw instance receiving RTP from osmo-bts 1.2.3
that sometimes the seqno was reset to 0 (while tx_timestamp was kept
properly). This seems to be the only possible way osmo-bts can reset the
seqno to 0 (calling rtp_session_reset()), since osmo_rtp_socket_create
already sets it to other values and inside ortp rtp_session_reset() is
the only one setting it to 0.
If SSRC changes, we are fine resetting some Rx state, which is done by
calling rtp_session_resync. However, calling rtp_session_reset() is too
much, since it erases other stuff like Tx state, which sholdn't be
affected in this case, since we are still transmitting the same stream.

Related: OS#3104
Related: OS#3299
Related: SYS#5498
Fixes: 28eeb6bc9365bbe47125775fcb1f696317c22466

Change-Id: Ic6006b4991c85413b009b70f8f3a6f97c41990ec
M src/trau/osmo_ortp.c
1 file changed, 2 insertions(+), 2 deletions(-)

  Jenkins Builder: Verified
  daniel: Looks good to me, but someone else must approve
  osmith: Looks good to me, but someone else must approve
  Hoernchen: Looks good to me, but someone else must approve
  pespin: Looks good to me, approved

diff --git a/src/trau/osmo_ortp.c b/src/trau/osmo_ortp.c
index b72f681..011f097 100644
--- a/src/trau/osmo_ortp.c
+++ b/src/trau/osmo_ortp.c
@@ -142,8 +142,8 @@
 	uint32_t ssrc = rtp_session_get_recv_ssrc(rs);
-	     "osmo-ortp(%d): ssrc_changed to 0x%08x, resetting\n", port, ssrc);
-	rtp_session_reset(rs);
+	     "osmo-ortp(%d): ssrc_changed to 0x%08x, resyncing\n", port, ssrc);
+	rtp_session_resync(rs);
 static void ortp_sig_cb_pt(RtpSession *rs, void *data)

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Gerrit-Project: libosmo-abis
Gerrit-Branch: master
Gerrit-Change-Id: Ic6006b4991c85413b009b70f8f3a6f97c41990ec
Gerrit-Change-Number: 24966
Gerrit-PatchSet: 1
Gerrit-Owner: pespin <pespin at>
Gerrit-Reviewer: Hoernchen <ewild at>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: daniel <dwillmann at>
Gerrit-Reviewer: dexter <pmaier at>
Gerrit-Reviewer: laforge <laforge at>
Gerrit-Reviewer: osmith <osmith at>
Gerrit-Reviewer: pespin <pespin at>
Gerrit-MessageType: merged
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