[codecs filter] send + receive SDP via MNCC
Transmit and receive full SDP information via MNCC, to accurately pass
codecs choices between the call legs.
In msc_vlr_test_call.c test_call_mt(), show that when receiving MNCC,
the codec information in SDP overrules the Bearer Cap codec information
-- we expect to still receive inaccurate Bearer Cap from e.g.
osmo-sip-connector, because we have chosen to add SDP to MNCC instead of
trying to fix the codecs represented in Bearer Cap.
For internal MNCC, the MT call leg now knows which codec the MO has
chosen and assigned.
For external MNCC, osmo-sip-connector receives SDP about our codecs
choices and sends it in SIP messages, and we also receive the full SDP
information from the remote SIP leg.
Update the SDP in codec_filter every time it is received, to always have
the latest SDP information from the remote leg.
CC MNCC
| ---ALERTING--> | add local side SDP to MNCC msg
| <--ALERTING--- | store remote side SDP
| <--SETUP-RESP- | store remote side SDP
| --SETUP-CNF--> | add local side SDP to MNCC msg
| -RTP-CREATE--> | use codec_filter, add local side SDP to MNCC msg
| <-RTP-CONNECT- | store remote side SDP
There still is one problem: when initiating MNCC, we do not yet know the
RTP address and port to be used for the CN side, because the CN CRCX
happens later. So far we send 0.0.0.0:0 as RTP endpoint in the SDP,
until the CN CRCX is done. A subsequent patch moves CN CRCX to an
earlier time, adding proper RTP information right from the start.
Related: SYS#5066
Change-Id: Ie0668c0e079ec69da1532b52d00621efe114fc2c
diff --git a/src/libmsc/gsm_04_08_cc.c b/src/libmsc/gsm_04_08_cc.c
index 214d81f..dd2c776 100644
--- a/src/libmsc/gsm_04_08_cc.c
+++ b/src/libmsc/gsm_04_08_cc.c
@@ -571,6 +571,8 @@
unsigned int payload_len = msgb_l3len(msg) - sizeof(*gh);
struct tlv_parsed tp;
struct gsm_mncc setup;
+ struct sdp_msg *sdp;
+ int rc;
gsm48_start_guard_timer(trans);
@@ -680,6 +682,18 @@
rate_ctr_inc(rate_ctr_group_get_ctr(trans->net->msc_ctrs, MSC_CTR_CALL_MO_SETUP));
+ /* FUTURE: so far this is composing SDP although the RTP address is not established yet (sending 0.0.0.0:0).
+ * Subsequent patch 'do CN CRCX first' (Ie433db1ba0c46d4b97538a969233c155cefac21c) changes the ordering so that
+ * the CN CRCX is completed before dispatching CC SETUP to remote, so that a valid RTP address is set. */
+
+ sdp = trans->cc.codecs.result.audio_codecs.count ? &trans->cc.codecs.result : NULL;
+ rc = sdp_msg_to_sdp_str_buf(setup.sdp, sizeof(setup.sdp), sdp);
+ if (rc >= sizeof(setup.sdp)) {
+ LOG_TRANS(trans, LOGL_ERROR, "MNCC_SETUP_IND: SDP too long (%d > %zu bytes)\n", rc, sizeof(setup.sdp));
+ trans_free(trans);
+ return -EINVAL;
+ }
+
/* indicate setup to MNCC */
mncc_recvmsg(trans->net, trans, MNCC_SETUP_IND, &setup);
@@ -689,6 +703,17 @@
return 0;
}
+static void rx_mncc_sdp(struct gsm_trans *trans, uint32_t mncc_msg_type, const char *sdp)
+{
+ int rc;
+ if (!sdp[0])
+ return;
+ rc = sdp_msg_from_sdp_str(&trans->cc.codecs.remote, sdp);
+ if (rc)
+ LOG_TRANS_CAT(trans, DMNCC, LOGL_ERROR, "rx %s: Failed to parse SDP: %d\n",
+ get_mncc_name(mncc_msg_type), rc);
+}
+
static int gsm48_cc_tx_setup(struct gsm_trans *trans, void *arg)
{
struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 CC SETUP");
@@ -741,17 +766,15 @@
codec_filter_set_ran(&trans->cc.codecs, trans->msc_a->c.ran->type);
codec_filter_set_bss(&trans->cc.codecs, &trans->msc_a->cc.compl_l3_codec_list_bss_supported);
/* sdp.remote: if SDP is included in the MNCC, take that as definitive list of remote audio codecs. */
- if (setup->sdp[0]) {
- rc = sdp_msg_from_sdp_str(&trans->cc.codecs.remote, setup->sdp);
- if (rc)
- LOG_TRANS(trans, LOGL_ERROR, "Failed to parse remote call leg SDP: %d\n", rc);
- }
+ rx_mncc_sdp(trans, setup->msg_type, setup->sdp);
/* sdp.remote: if there is no SDP information or we failed to parse it, try using the Bearer Capability from
* MNCC, if any. */
if (!trans->cc.codecs.remote.audio_codecs.count && (setup->fields & MNCC_F_BEARER_CAP)) {
trans->cc.codecs.remote = (struct sdp_msg){};
sdp_audio_codecs_from_bearer_cap(&trans->cc.codecs.remote.audio_codecs,
&setup->bearer_cap);
+ LOG_TRANS_CAT(trans, DMNCC, LOGL_DEBUG, "rx %s Bearer Cap: remote=%s\n",
+ get_mncc_name(setup->msg_type), sdp_msg_to_str(&trans->cc.codecs.remote));
}
if (!trans->cc.codecs.remote.audio_codecs.count)
LOG_TRANS(trans, LOGL_INFO,
@@ -931,6 +954,7 @@
unsigned int payload_len = msgb_l3len(msg) - sizeof(*gh);
struct tlv_parsed tp;
struct gsm_mncc alerting;
+ int rc;
gsm48_stop_cc_timer(trans);
gsm48_start_cc_timer(trans, 0x301, GSM48_T301);
@@ -960,6 +984,16 @@
new_cc_state(trans, GSM_CSTATE_CALL_RECEIVED);
+ codec_filter_run(&trans->cc.codecs);
+ LOG_TRANS(trans, LOGL_DEBUG, "codecs: %s\n", codec_filter_to_str(&trans->cc.codecs));
+ rc = sdp_msg_to_sdp_str_buf(alerting.sdp, sizeof(alerting.sdp), &trans->cc.codecs.result);
+ if (rc >= sizeof(alerting.sdp)) {
+ LOG_TRANS(trans, LOGL_ERROR, "MNCC_ALERT_IND: SDP too long (%d > %zu bytes)\n",
+ rc, sizeof(alerting.sdp));
+ trans_free(trans);
+ return -EINVAL;
+ }
+
return mncc_recvmsg(trans->net, trans, MNCC_ALERT_IND,
&alerting);
}
@@ -984,6 +1018,19 @@
new_cc_state(trans, GSM_CSTATE_CALL_DELIVERED);
+ if (alerting->sdp[0]) {
+ struct call_leg *cl = trans->msc_a->cc.call_leg;
+ struct rtp_stream *rtp_cn = cl ? cl->rtp[RTP_TO_CN] : NULL;
+ codec_filter_set_remote(&trans->cc.codecs, alerting->sdp);
+ codec_filter_run(&trans->cc.codecs);
+ LOG_TRANS(trans, LOGL_DEBUG, "%s codecs: %s\n",
+ get_mncc_name(alerting->msg_type), codec_filter_to_str(&trans->cc.codecs));
+ if (rtp_cn) {
+ rtp_stream_set_remote_addr_and_codecs(rtp_cn, &trans->cc.codecs.remote);
+ rtp_stream_commit(rtp_cn);
+ }
+ }
+
return trans_tx_gsm48(trans, msg);
}
@@ -1030,6 +1077,21 @@
new_cc_state(trans, GSM_CSTATE_CONNECT_IND);
+ /* Received an MNCC_SETUP_RSP with the remote leg's SDP information. Apply codec choice. */
+ if (connect->sdp[0]) {
+ struct call_leg *cl = trans->msc_a->cc.call_leg;
+ struct rtp_stream *rtp_cn = cl ? cl->rtp[RTP_TO_CN] : NULL;
+ rx_mncc_sdp(trans, connect->msg_type, connect->sdp);
+ codec_filter_run(&trans->cc.codecs);
+ LOG_TRANS(trans, LOGL_DEBUG, "%s codecs: %s\n",
+ get_mncc_name(connect->msg_type),
+ codec_filter_to_str(&trans->cc.codecs));
+ if (rtp_cn) {
+ rtp_stream_set_remote_addr_and_codecs(rtp_cn, &trans->cc.codecs.remote);
+ rtp_stream_commit(rtp_cn);
+ }
+ }
+
return trans_tx_gsm48(trans, msg);
}
@@ -1072,6 +1134,8 @@
new_cc_state(trans, GSM_CSTATE_CONNECT_REQUEST);
rate_ctr_inc(rate_ctr_group_get_ctr(trans->net->msc_ctrs, MSC_CTR_CALL_MT_CONNECT));
+ codec_filter_run(&trans->cc.codecs);
+ sdp_msg_to_sdp_str_buf(connect.sdp, sizeof(connect.sdp), &trans->cc.codecs.result);
return mncc_recvmsg(trans->net, trans, MNCC_SETUP_CNF, &connect);
}
@@ -1782,7 +1846,7 @@
static int mncc_recv_rtp(struct gsm_network *net, struct gsm_trans *trans, uint32_t callref,
int cmd, struct osmo_sockaddr_str *rtp_addr, uint32_t payload_type,
- uint32_t payload_msg_type)
+ uint32_t payload_msg_type, const struct sdp_msg *sdp)
{
uint8_t data[sizeof(struct gsm_mncc)];
struct gsm_mncc_rtp *rtp;
@@ -1798,12 +1862,14 @@
}
rtp->payload_type = payload_type;
rtp->payload_msg_type = payload_msg_type;
+ if (sdp)
+ sdp_msg_to_sdp_str_buf(rtp->sdp, sizeof(rtp->sdp), sdp);
return mncc_recvmsg(net, trans, cmd, (struct gsm_mncc *)data);
}
static void mncc_recv_rtp_err(struct gsm_network *net, struct gsm_trans *trans, uint32_t callref, int cmd)
{
- mncc_recv_rtp(net, trans, callref, cmd, NULL, 0, 0);
+ mncc_recv_rtp(net, trans, callref, cmd, NULL, 0, 0, NULL);
}
static int tch_rtp_create(struct gsm_network *net, const struct gsm_mncc_rtp *rtp)
@@ -1871,7 +1937,7 @@
}
return mncc_recv_rtp(net, trans, trans->callref, MNCC_RTP_CREATE, rtp_cn_local,
- codec->payload_type, mncc_payload_msg_type);
+ codec->payload_type, mncc_payload_msg_type, &trans->cc.codecs.result);
}
static int tch_rtp_connect(struct gsm_network *net, const struct gsm_mncc_rtp *rtp)
@@ -1879,17 +1945,6 @@
struct gsm_trans *trans;
struct call_leg *cl;
struct rtp_stream *rtps;
- struct osmo_sockaddr_str rtp_addr;
-
- /* FIXME: in *rtp we should get the codec information of the remote
- * leg. We will have to populate trans->conn->rtp.codec_cn with a
- * meaningful value based on this information but unfortunately we
- * can't do that yet because the mncc API can not signal dynamic
- * payload types yet. This must be fixed first. Also there may be
- * additional members necessary in trans->conn->rtp because we
- * somehow need to deal with dynamic payload types that do not
- * comply to 3gpp's assumptions of payload type numbers on the A
- * interface. See also related tickets: OS#3399 and OS1683 */
/* Find callref */
trans = trans_find_by_callref(net, rtp->callref);
@@ -1916,12 +1971,20 @@
return -EINVAL;
}
- if (osmo_sockaddr_str_from_sockaddr(&rtp_addr, &rtp->addr) < 0) {
- LOG_TRANS_CAT(trans, DMNCC, LOGL_ERROR, "RTP connect with invalid IP addr\n");
- mncc_recv_rtp_err(net, trans, rtp->callref, MNCC_RTP_CONNECT);
- return -EINVAL;
+ rx_mncc_sdp(trans, rtp->msg_type, rtp->sdp);
+ rtp_stream_set_remote_addr_and_codecs(rtps, &trans->cc.codecs.remote);
+
+ if (!osmo_sockaddr_str_is_nonzero(&rtps->remote)) {
+ /* Didn't get an IP address from SDP. Try legacy MNCC IP address */
+ struct osmo_sockaddr_str rtp_addr;
+ if (osmo_sockaddr_str_from_sockaddr(&rtp_addr, &rtp->addr) < 0) {
+ LOG_TRANS_CAT(trans, DMNCC, LOGL_ERROR, "RTP connect with invalid IP addr\n");
+ mncc_recv_rtp_err(net, trans, rtp->callref, MNCC_RTP_CONNECT);
+ return -EINVAL;
+ }
+ rtp_stream_set_remote_addr(rtps, &rtp_addr);
}
- rtp_stream_set_remote_addr(rtps, &rtp_addr);
+
rtp_stream_commit(rtps);
return 0;
}
@@ -2103,6 +2166,9 @@
return -ENOMEM;
}
+ /* Remember remote SDP, if any */
+ rx_mncc_sdp(trans, data->msg_type, data->sdp);
+
/* If subscriber has no conn */
if (!msc_a) {
/* This condition will return before the common logging of the received MNCC message below, so