From d3d62f4d40bfe204adebb646375da41ccf04ced7 Mon Sep 17 00:00:00 2001 From: Neels Hofmeyr Date: Fri, 21 Oct 2016 01:35:57 +0200 Subject: 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: If0887b0b7714fc204f2addab2d43d44bb283ba21 --- openbsc/include/openbsc/mgcp_internal.h | 1 + openbsc/src/libmgcp/mgcp_network.c | 9 +++++++++ 2 files changed, 10 insertions(+) diff --git a/openbsc/include/openbsc/mgcp_internal.h b/openbsc/include/openbsc/mgcp_internal.h index b58eb9b58..4e215b8f1 100644 --- a/openbsc/include/openbsc/mgcp_internal.h +++ b/openbsc/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/openbsc/src/libmgcp/mgcp_network.c b/openbsc/src/libmgcp/mgcp_network.c index 5686e5944..b64e25dd7 100644 --- a/openbsc/src/libmgcp/mgcp_network.c +++ b/openbsc/src/libmgcp/mgcp_network.c @@ -666,6 +666,14 @@ 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 = &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); @@ -685,6 +693,7 @@ int mgcp_send(struct mgcp_endpoint *endp, int dest, int is_rtp, ntohs(rtp_end->rtp_port), ntohs(rtp_end->rtcp_port) ); + return mgcp_udp_send(rtp_end->rtcp.fd, &rtp_end->addr, rtp_end->rtcp_port, buf, rc); -- cgit v1.2.3