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/* Filter/overlay codec selections for a voice call, across MS, RAN and CN limitations */
/*
* (C) 2019-2023 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
* All Rights Reserved
*
* Author: Neels Hofmeyr
*
* 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/gsm/protocol/gsm_08_08.h>
#include <osmocom/msc/codec_filter.h>
#include <osmocom/msc/codec_mapping.h>
#include <osmocom/msc/ran_infra.h>
#include <osmocom/msc/debug.h>
void codec_filter_set_ran(struct codec_filter *codec_filter, const struct sdp_audio_codecs *codecs)
{
const struct sdp_audio_codec *c;
codec_filter->ran = (struct sdp_audio_codecs){};
/* Add codecs one by one, to resolve any payload type number conflicts or duplicates. */
sdp_audio_codecs_foreach (c, codecs)
sdp_audio_codecs_add_copy(&codec_filter->ran, c, true, true);
}
void codec_filter_set_bss(struct codec_filter *codec_filter,
const struct gsm0808_speech_codec_list *codec_list_bss_supported)
{
codec_filter->bss = (struct sdp_audio_codecs){};
if (codec_list_bss_supported)
sdp_audio_codecs_from_speech_codec_list(&codec_filter->bss, codec_list_bss_supported);
}
/* Render intersections of all known audio codec constraints to reach a resulting choice of favorite audio codec, plus
* possible set of alternative audio codecs, in codec_filter->result. (The result.rtp address remains unchanged.) */
int codec_filter_run(struct codec_filter *codec_filter, struct sdp_msg *result, const struct sdp_msg *remote)
{
struct sdp_audio_codecs *r = &result->audio_codecs;
struct sdp_audio_codec *a = &codec_filter->assignment;
*r = codec_filter->ran;
if (codec_filter->ms.count)
sdp_audio_codecs_intersection(r, &codec_filter->ms, false);
if (codec_filter->bss.count)
sdp_audio_codecs_intersection(r, &codec_filter->bss, false);
if (remote->audio_codecs.count)
sdp_audio_codecs_intersection(r, &remote->audio_codecs, true);
if (sdp_audio_codec_is_set(a)) {
/* Assignment has completed, the chosen codec should be the first of the resulting SDP.
* If present, make sure this is listed in first place.
* If 'select' is NULL, the assigned codec is not present in the intersection of possible choices for
* TFO. Just omit the assigned codec from the filter result, and it is the CC code's responsibility to
* detect this and assign a working codec instead. */
struct sdp_audio_codec *select = sdp_audio_codecs_by_descr(r, a);
if (select)
sdp_audio_codecs_select(r, select);
}
return 0;
}
int codec_filter_to_str_buf(char *buf, size_t buflen, const struct codec_filter *codec_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 (sdp_audio_codec_is_set(&codec_filter->assignment)) {
OSMO_STRBUF_PRINTF(sb, " assigned=");
OSMO_STRBUF_APPEND(sb, sdp_audio_codec_to_str_buf, &codec_filter->assignment);
}
if (remote->audio_codecs.count
|| osmo_sockaddr_str_is_nonzero(&remote->rtp)) {
OSMO_STRBUF_PRINTF(sb, " remote=");
OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, remote);
}
if (codec_filter->ms.count) {
OSMO_STRBUF_PRINTF(sb, " MS={");
OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ms);
OSMO_STRBUF_PRINTF(sb, "}");
}
if (codec_filter->bss.count) {
OSMO_STRBUF_PRINTF(sb, " bss={");
OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->bss);
OSMO_STRBUF_PRINTF(sb, "}");
}
OSMO_STRBUF_PRINTF(sb, " RAN={");
OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ran);
OSMO_STRBUF_PRINTF(sb, "}");
OSMO_STRBUF_PRINTF(sb, ")");
return sb.chars_needed;
}
char *codec_filter_to_str_c(void *ctx, const struct codec_filter *codec_filter, const struct sdp_msg *result,
const struct sdp_msg *remote)
{
OSMO_NAME_C_IMPL(ctx, 128, "codec_filter_to_str_c-ERROR", codec_filter_to_str_buf, codec_filter, result, remote)
}
const char *codec_filter_to_str(const struct codec_filter *codec_filter, const struct sdp_msg *result,
const struct sdp_msg *remote)
{
return codec_filter_to_str_c(OTC_SELECT, codec_filter, result, remote);
}
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