diff options
authorNeels Hofmeyr <nhofmeyr@sysmocom.de>2017-03-16 16:14:34 +0100
committerNeels Hofmeyr <nhofmeyr@sysmocom.de>2017-08-11 18:34:01 +0200
commit76af13e4d635377c091169aa948c225c815d170b (patch)
parent08bdb29632de633d8abb53bbe6f2e07b467fb189 (diff)
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
2 files changed, 8 insertions, 0 deletions
diff --git a/include/openbsc/mgcp_internal.h b/include/openbsc/mgcp_internal.h
index b58eb9b58..4e215b8f1 100644
--- a/include/openbsc/mgcp_internal.h
+++ b/include/openbsc/mgcp_internal.h
@@ -64,6 +64,7 @@ struct mgcp_rtp_state {
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 c9fe17973..a1c7e85fc 100644
--- a/src/libmgcp/mgcp_network.c
+++ b/src/libmgcp/mgcp_network.c
@@ -667,6 +667,13 @@ int mgcp_send(struct mgcp_endpoint *endp, int dest, int is_rtp,
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->rtp_port, buf, len);