Add initial CSD support with external MNCC
Implement and use CSD bearer service logic (with similar audio codec code):
* csd_filter (codec_filter)
* csd_bs (sdp_audio_codec)
* csd_bs_list (sdp_audio_codecs)
Related: OS#4394
Change-Id: Ide8b8321e0401dcbe35da2ec9cee0abca821d99a
diff --git a/src/libmsc/csd_filter.c b/src/libmsc/csd_filter.c
new file mode 100644
index 0000000..0f428cf
--- /dev/null
+++ b/src/libmsc/csd_filter.c
@@ -0,0 +1,157 @@
+/* Filter/overlay bearer service selections 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/mgcp_client/mgcp_client.h>
+
+#include <osmocom/msc/csd_filter.h>
+
+static void add_all_geran_bs(struct csd_bs_list *list)
+{
+ /* See 3GPP TS 122.002 Bearer Services */
+ /* In order of preference. TODO: make configurable */
+
+ /* GSM-R */
+ csd_bs_list_add_bs(list, CSD_BS_24_T_V110_2k4);
+ csd_bs_list_add_bs(list, CSD_BS_25_T_V110_4k8);
+ csd_bs_list_add_bs(list, CSD_BS_26_T_V110_9k6);
+
+ /* Other */
+ csd_bs_list_add_bs(list, CSD_BS_21_T_V110_0k3);
+ csd_bs_list_add_bs(list, CSD_BS_22_T_V110_1k2);
+ csd_bs_list_add_bs(list, CSD_BS_21_NT_V110_0k3);
+ csd_bs_list_add_bs(list, CSD_BS_22_NT_V110_1k2);
+ csd_bs_list_add_bs(list, CSD_BS_24_NT_V110_2k4);
+ csd_bs_list_add_bs(list, CSD_BS_25_NT_V110_4k8);
+ csd_bs_list_add_bs(list, CSD_BS_26_NT_V110_9k6);
+ csd_bs_list_add_bs(list, CSD_BS_31_T_V110_1k2);
+ csd_bs_list_add_bs(list, CSD_BS_32_T_V110_2k4);
+ csd_bs_list_add_bs(list, CSD_BS_33_T_V110_4k8);
+ csd_bs_list_add_bs(list, CSD_BS_34_T_V110_9k6);
+}
+
+static void add_all_utran_bs(struct csd_bs_list *list)
+{
+ /* See 3GPP TS 122.002 Bearer Services */
+ /* In order of preference. TODO: make configurable */
+ csd_bs_list_add_bs(list, CSD_BS_21_NT_V110_0k3);
+ csd_bs_list_add_bs(list, CSD_BS_22_NT_V110_1k2);
+ csd_bs_list_add_bs(list, CSD_BS_24_NT_V110_2k4);
+ csd_bs_list_add_bs(list, CSD_BS_25_NT_V110_4k8);
+ csd_bs_list_add_bs(list, CSD_BS_26_NT_V110_9k6);
+}
+
+void csd_filter_set_ran(struct csd_filter *filter, enum osmo_rat_type ran_type)
+{
+ filter->ran = (struct csd_bs_list){};
+
+ switch (ran_type) {
+ default:
+ case OSMO_RAT_GERAN_A:
+ add_all_geran_bs(&filter->ran);
+ break;
+ case OSMO_RAT_UTRAN_IU:
+ add_all_utran_bs(&filter->ran);
+ break;
+ }
+}
+
+int csd_filter_run(struct csd_filter *filter, struct sdp_msg *result, const struct sdp_msg *remote)
+{
+ struct csd_bs_list *r = &result->bearer_services;
+ enum csd_bs a = filter->assignment;
+
+ *r = filter->ran;
+
+ if (filter->ms.count)
+ csd_bs_list_intersection(r, &filter->ms);
+ if (filter->bss.count)
+ csd_bs_list_intersection(r, &filter->bss);
+ if (remote->bearer_services.count)
+ csd_bs_list_intersection(r, &remote->bearer_services);
+
+ /* Future: If osmo-msc were able to trigger a re-assignment [...] see
+ * comment in codec_filter_run(). */
+
+ if (a) {
+ *r = (struct csd_bs_list){};
+ csd_bs_list_add_bs(r, a);
+ }
+
+ result->audio_codecs.count = 1;
+ result->audio_codecs.codec[0] = (struct sdp_audio_codec){
+ .payload_type = CODEC_CLEARMODE,
+ .subtype_name = "CLEARMODE",
+ .rate = 8000,
+ };
+
+ return 0;
+}
+
+
+int csd_filter_to_str_buf(char *buf, size_t buflen, const struct csd_filter *filter,
+ const struct sdp_msg *result, const struct sdp_msg *remote)
+{
+ struct osmo_strbuf sb = { .buf = buf, .len = buflen };
+ OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, result);
+ OSMO_STRBUF_PRINTF(sb, " (from:");
+
+ if (filter->assignment) {
+ OSMO_STRBUF_PRINTF(sb, " assigned=");
+ OSMO_STRBUF_APPEND(sb, csd_bs_to_str_buf, filter->assignment);
+ }
+
+ if (remote->bearer_services.count || osmo_sockaddr_str_is_nonzero(&remote->rtp)) {
+ OSMO_STRBUF_PRINTF(sb, " remote=");
+ OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, remote);
+ }
+
+ if (filter->ms.count) {
+ OSMO_STRBUF_PRINTF(sb, " MS={");
+ OSMO_STRBUF_APPEND(sb, csd_bs_list_to_str_buf, &filter->ms);
+ OSMO_STRBUF_PRINTF(sb, "}");
+ }
+
+ if (filter->bss.count) {
+ OSMO_STRBUF_PRINTF(sb, " bss={");
+ OSMO_STRBUF_APPEND(sb, csd_bs_list_to_str_buf, &filter->bss);
+ OSMO_STRBUF_PRINTF(sb, "}");
+ }
+
+ OSMO_STRBUF_PRINTF(sb, " RAN={");
+ OSMO_STRBUF_APPEND(sb, csd_bs_list_to_str_buf, &filter->ran);
+ OSMO_STRBUF_PRINTF(sb, "}");
+
+ OSMO_STRBUF_PRINTF(sb, ")");
+
+ return sb.chars_needed;
+}
+
+char *csd_filter_to_str_c(void *ctx, const struct csd_filter *filter, const struct sdp_msg *result, const struct sdp_msg *remote)
+{
+ OSMO_NAME_C_IMPL(ctx, 128, "csd_filter_to_str_c-ERROR", csd_filter_to_str_buf, filter, result, remote)
+}
+
+const char *csd_filter_to_str(const struct csd_filter *filter, const struct sdp_msg *result, const struct sdp_msg *remote)
+{
+ return csd_filter_to_str_c(OTC_SELECT, filter, result, remote);
+}