codec_filter_set_ms_from_bc: prepare for CSD
In all the places where codec_filter_ functions get called, for CSD we
will need to filter the bearer services. Add a new
transaction_cc.c file for functions that either combine the
codec_filter_ function with logic for CSD and voice calls or just call
the existing codec_filter function and a new csd_filter function.
Start with moving codec_filter_set_ms_from_bc to this new file, it will
be extended with a case for CSD in a future patch.
Related: OS#4394
Change-Id: If225f2a299ce6bc9ae35a17d6f591d889f49155e
diff --git a/src/libmsc/transaction_cc.c b/src/libmsc/transaction_cc.c
new file mode 100644
index 0000000..3a0db2c
--- /dev/null
+++ b/src/libmsc/transaction_cc.c
@@ -0,0 +1,43 @@
+/* Filter/overlay codec and CSD bearer service selections for voice calls/CSD,
+ * across MS, RAN and CN limitations
+ *
+ * (C) 2023 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Oliver Smith
+ *
+ * SPDX-License-Identifier: AGPL-3.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <osmocom/msc/transaction_cc.h>
+
+void trans_cc_filter_set_ms_from_bc(struct gsm_trans *trans, const struct gsm_mncc_bearer_cap *bcap)
+{
+ trans->cc.codecs.ms = (struct sdp_audio_codecs){0};
+
+ if (!bcap)
+ return;
+
+ switch (bcap->transfer) {
+ case GSM48_BCAP_ITCAP_SPEECH:
+ sdp_audio_codecs_from_bearer_cap(&trans->cc.codecs.ms, bcap);
+ break;
+ default:
+ LOG_TRANS(trans, LOGL_ERROR, "Handling of information transfer capability %d not implemented\n",
+ bcap->transfer);
+ break;
+ }
+}