[codecs filter] use filter result in MT DTAP CC Setup
So far, we just forwarded the Bearer Capabilities received in MNCC from
the remote MO call leg, and omitted Bearer Cap if the remote call leg
did not provide any.
Instead, always include Bearer Cap, and compose it from the codecs
filter result. Hence the Bearer Cap is now an intersection of MS, BSS
and remote call leg, instead of just the remote call leg.
Related: SYS#5066
Change-Id: I9586221ef56352b7ce4b2604ae0dc04554145a78
diff --git a/src/libmsc/gsm_04_08_cc.c b/src/libmsc/gsm_04_08_cc.c
index 269fd57..f0aca9c 100644
--- a/src/libmsc/gsm_04_08_cc.c
+++ b/src/libmsc/gsm_04_08_cc.c
@@ -695,6 +695,7 @@
struct gsm48_hdr *gh;
struct gsm_mncc *setup = arg;
int rc, trans_id;
+ struct gsm_mncc_bearer_cap bearer_cap;
gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
@@ -759,15 +760,42 @@
codec_filter_run(&trans->cc.codecs);
LOG_TRANS(trans, LOGL_DEBUG, "codecs: %s\n", codec_filter_to_str(&trans->cc.codecs));
- /* NEAR FUTURE: upcoming patch will use the codecs filter to determine the Bearer Cap to send to the MS.
- * So far just gathering information in the new codecs filter. */
- /* bearer capability */
- if (setup->fields & MNCC_F_BEARER_CAP) {
- /* Create a copy of the bearer capability in the transaction struct, so we
- * can use this information later */
- memcpy(&trans->bearer_cap, &setup->bearer_cap, sizeof(trans->bearer_cap));
- gsm48_encode_bearer_cap(msg, 0, &setup->bearer_cap);
+ /* Compose Bearer Capability information that reflects only the codecs (Speech Versions) remaining after
+ * intersecting MS, BSS and remote call leg restrictions. To store in trans for later use, and to include in
+ * the outgoing CC Setup message. */
+ bearer_cap = (struct gsm_mncc_bearer_cap){
+ .speech_ver = { -1 },
+ };
+ sdp_audio_codecs_to_bearer_cap(&bearer_cap, &trans->cc.codecs.result.audio_codecs);
+ rc = bearer_cap_set_radio(&bearer_cap);
+ if (rc) {
+ LOG_TRANS(trans, LOGL_ERROR, "Error composing Bearer Capability for CC Setup\n");
+ trans_free(trans);
+ msgb_free(msg);
+ return rc;
}
+ /* Create a copy of the bearer capability in the transaction struct, so we can use this information later */
+ /* TODO: we should be able to drop trans->bearer_cap, replaced by the codecs filter. Verify this.
+ * So far let's just store it there like previous code did. */
+ trans->bearer_cap = bearer_cap;
+ /* If no resulting codecs remain, error out. We cannot find a codec that matches both call legs. If the MGW were
+ * able to transcode, we could use non-identical codecs on each conn of the MGW endpoint, but we are aiming for
+ * finding a matching codec. */
+ if (bearer_cap.speech_ver[0] == -1) {
+ LOG_TRANS(trans, LOGL_ERROR, "%s: no codec match possible: %s\n",
+ get_mncc_name(setup->msg_type), codec_filter_to_str(&trans->cc.codecs));
+
+ /* incompatible codecs */
+ rc = mncc_release_ind(trans->net, trans, trans->callref,
+ GSM48_CAUSE_LOC_PRN_S_LU,
+ GSM48_CC_CAUSE_INCOMPAT_DEST /* TODO: correct cause code? */);
+ trans->callref = 0;
+ trans_free(trans);
+ msgb_free(msg);
+ return rc;
+ }
+ gsm48_encode_bearer_cap(msg, 0, &bearer_cap);
+
/* facility */
if (setup->fields & MNCC_F_FACILITY)
gsm48_encode_facility(msg, 0, &setup->facility);