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

3 files changed, 34 insertions, 1 deletions

diff --git a/include/osmocom/msc/Makefile.am b/include/osmocom/msc/Makefile.am
index 34b4902ce..948021a0c 100644
--- a/include/osmocom/msc/Makefile.am
+++ b/include/osmocom/msc/Makefile.am
@@ -49,6 +49,7 @@ noinst_HEADERS = \
 	silent_call.h \
 	sms_queue.h \
 	transaction.h \
+	transaction_cc.h \
 	vlr.h \
 	vlr_sgs.h \
 	vty.h \
diff --git a/include/osmocom/msc/codec_filter.h b/include/osmocom/msc/codec_filter.h
index b488e9831..c90388dcc 100644
--- a/include/osmocom/msc/codec_filter.h
+++ b/include/osmocom/msc/codec_filter.h
@@ -54,7 +54,6 @@ struct codec_filter {
 
 void codec_filter_init(struct codec_filter *codec_filter);
 void codec_filter_set_ran(struct codec_filter *codec_filter, enum osmo_rat_type ran_type);
-void codec_filter_set_ms_from_bc(struct codec_filter *codec_filter, const struct gsm_mncc_bearer_cap *ms_bearer_cap);
 void codec_filter_set_bss(struct codec_filter *codec_filter,
 			  const struct gsm0808_speech_codec_list *codec_list_bss_supported);
 int codec_filter_set_remote(struct codec_filter *codec_filter, const char *remote_sdp);
diff --git a/include/osmocom/msc/transaction_cc.h b/include/osmocom/msc/transaction_cc.h
new file mode 100644
index 000000000..df0f9d841
--- /dev/null
+++ b/include/osmocom/msc/transaction_cc.h
@@ -0,0 +1,33 @@
+/* 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/>.
+ */
+
+#pragma once
+
+#include <osmocom/gsm/mncc.h>
+
+#include <osmocom/msc/codec_mapping.h>
+#include <osmocom/msc/transaction.h>
+#include <osmocom/msc/vlr.h>
+
+void trans_cc_filter_set_ms_from_bc(struct gsm_trans *trans, const struct gsm_mncc_bearer_cap *bcap);