[PATCH] osmo-msc[master]: mgcp: hack RAB success from nano3G: patch first RTP payload

[Neels Hofmeyr]

Hello Jenkins Builder,

I'd like you to reexamine a change.  Please visit

    https://gerrit.osmocom.org/3349

to look at the new patch set (#2).

mgcp: hack RAB success from nano3G: patch first RTP payload

The ip.access nano3G needs the first RTP payload's first two bytes to read hex
'e400', or it will reject the RAB assignment. Add flag
patched_first_rtp_payload to mgcp_rtp_state to detect the first RTP payload on
a stream, and overwrite its first bytes with e400. This should probably be
configurable, but seems to not harm other femto cells (as long as we patch only
the first RTP payload in each stream). Only do this when sending to the BTS
side.

Change-Id: I5eff04dcb0936e21690e427ae5e49228cd459bd4
---
M include/openbsc/mgcp_internal.h
M src/libmgcp/mgcp_network.c
2 files changed, 8 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmo-msc refs/changes/49/3349/2

diff --git a/include/openbsc/mgcp_internal.h b/include/openbsc/mgcp_internal.h
index b58eb9b..4e215b8 100644
--- a/include/openbsc/mgcp_internal.h
+++ b/include/openbsc/mgcp_internal.h
@@ -64,6 +64,7 @@
 	uint32_t stats_jitter;
 	int32_t stats_transit;
 	int stats_cycles;
+	bool patched_first_rtp_payload;
 };
 
 struct mgcp_rtp_codec {
diff --git a/src/libmgcp/mgcp_network.c b/src/libmgcp/mgcp_network.c
index c9fe179..a1c7e85 100644
--- a/src/libmgcp/mgcp_network.c
+++ b/src/libmgcp/mgcp_network.c
@@ -667,6 +667,13 @@
 			forward_data(rtp_end->rtp.fd, &endp->taps[tap_idx],
 				     buf, len);
 
+			if (tap_idx == MGCP_TAP_BTS_OUT
+			    && !rtp_state->patched_first_rtp_payload) {
+				uint8_t *data = (uint8_t*)&buf[12];
+				osmo_hexparse("e400", data, 2);
+				rtp_state->patched_first_rtp_payload = true;
+			}
+
 			rc = mgcp_udp_send(rtp_end->rtp.fd,
 					   &rtp_end->addr,
 					   rtp_end->rtp_port, buf, len);

-- 
To view, visit https://gerrit.osmocom.org/3349
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I5eff04dcb0936e21690e427ae5e49228cd459bd4
Gerrit-PatchSet: 2
Gerrit-Project: osmo-msc
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: Jenkins Builder