mgcp: Optionally send ptime in SDP
Currently the SDP 'ptime' media attribute is never set in generated
MGCP responses.
This patch optionally includes the 'ptime' attribute if
packet_duration_ms is != 0. This behaviour can be enabled/disabled
by using the VTY command "sdp audio-payload send-ptime" (enabled by
default).
Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/libmgcp/mgcp_protocol.c b/openbsc/src/libmgcp/mgcp_protocol.c
index b8d1920..7d3ad74 100644
--- a/openbsc/src/libmgcp/mgcp_protocol.c
+++ b/openbsc/src/libmgcp/mgcp_protocol.c
@@ -230,11 +230,12 @@
const char *addr = endp->cfg->local_ip;
const char *fmtp_extra = endp->bts_end.fmtp_extra;
char sdp_record[4096];
+ int len;
if (!addr)
addr = endp->cfg->source_addr;
- snprintf(sdp_record, sizeof(sdp_record) - 1,
+ len = snprintf(sdp_record, sizeof(sdp_record) - 1,
"I: %u\n\n"
"v=0\r\n"
"o=- %u 23 IN IP4 %s\r\n"
@@ -247,7 +248,25 @@
endp->net_end.local_port, endp->bts_end.payload_type,
endp->bts_end.payload_type, endp->tcfg->audio_name,
fmtp_extra ? fmtp_extra : "", fmtp_extra ? "\r\n" : "");
+
+ if (len < 0 || len >= sizeof(sdp_record))
+ goto buffer_too_small;
+
+ if (endp->bts_end.packet_duration_ms > 0 && endp->tcfg->audio_send_ptime) {
+ int nchars = snprintf(sdp_record + len, sizeof(sdp_record) - len,
+ "a=ptime:%d\r\n",
+ endp->bts_end.packet_duration_ms);
+ if (nchars < 0 || nchars >= sizeof(sdp_record) - len)
+ goto buffer_too_small;
+
+ len += nchars;
+ }
return create_resp(endp, 200, " OK", msg, trans_id, NULL, sdp_record);
+
+buffer_too_small:
+ LOGP(DMGCP, LOGL_ERROR, "SDP buffer too small: %d (needed %d)\n",
+ sizeof(sdp_record), len);
+ return NULL;
}
/*
@@ -1109,6 +1128,7 @@
cfg->trunk.trunk_type = MGCP_TRUNK_VIRTUAL;
cfg->trunk.audio_name = talloc_strdup(cfg, "AMR/8000");
cfg->trunk.audio_payload = 126;
+ cfg->trunk.audio_send_ptime = 1;
cfg->trunk.omit_rtcp = 0;
INIT_LLIST_HEAD(&cfg->trunks);
@@ -1131,6 +1151,7 @@
trunk->trunk_nr = nr;
trunk->audio_name = talloc_strdup(cfg, "AMR/8000");
trunk->audio_payload = 126;
+ trunk->audio_send_ptime = 1;
trunk->number_endpoints = 33;
trunk->omit_rtcp = 0;
llist_add_tail(&trunk->entry, &cfg->trunks);