[codecs filter] store BSS codec list from Compl L3

The initial Compl L3 happens long before we establish a CC transaction.
Remember the Codec List (BSS Supported), so that we can feed the new
codecs filter with it. Subsequent patches implement feeding the filter.

Related: SYS#5066
Change-Id: I7cdc348218433141a43d2e42750af02591688240

include/osmocom/msc/msc_a.h

@@ -121,6 +121,9 @@ struct msc_a {
 	 *                   \-------RTP--> (ISUP) <--RTP--> <--RTP-->
 	 */
 	struct {
+		/* Codec List (BSS Supported) as received during Complete Layer 3 Information */
+		struct gsm0808_speech_codec_list compl_l3_codec_list_bss_supported;
+
 		/* All of the RTP stream handling */
 		struct call_leg *call_leg;
 		struct mncc_call *mncc_forwarding_to_remote_ran;

src/libmsc/msc_a.c

@@ -46,6 +46,7 @@
 #include <osmocom/msc/call_leg.h>
 #include <osmocom/msc/rtp_stream.h>
 #include <osmocom/msc/msc_ho.h>
+#include <osmocom/msc/codec_mapping.h>
 
 #define MSC_A_USE_WAIT_CLEAR_COMPLETE "wait-Clear-Complete"
 
@@ -1443,6 +1444,18 @@ int msc_a_ran_dec_from_msc_i(struct msc_a *msc_a, struct msc_a_ran_dec_data *d)
 		};
 		gsm0808_cell_id_to_cgi(&msc_a->via_cell, msg->compl_l3.cell_id);
 
+		/* If a codec list was sent along in the RAN_MSG_COMPL_L3, remember it for any upcoming codec
+		 * resolution. */
+		if (msg->compl_l3.codec_list_bss_supported) {
+			msc_a->cc.compl_l3_codec_list_bss_supported = *msg->compl_l3.codec_list_bss_supported;
+			if (log_check_level(msc_a->c.ran->log_subsys, LOGL_DEBUG)) {
+				struct sdp_audio_codecs ac = {};
+				sdp_audio_codecs_from_speech_codec_list(&ac, &msc_a->cc.compl_l3_codec_list_bss_supported);
+				LOG_MSC_A(msc_a, LOGL_DEBUG, "Complete Layer 3: Codec List (BSS Supported): %s\n",
+					  sdp_audio_codecs_to_str(&ac));
+			}
+		}
+
 		/* Submit the Complete Layer 3 Information DTAP */
 		rc = msc_a_up_l3(msc_a, msg->compl_l3.msg);
 		if (!rc) {