/* Filter/overlay codec selections for a voice call, across MS, RAN and CN limitations */ /* * (C) 2019-2022 by sysmocom - s.m.f.c. GmbH * All Rights Reserved * * Author: Neels Hofmeyr * * SPDX-License-Identifier: GPL-2.0+ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 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 General Public License for more details. */ #include #include #include #include /* Add all known payload types encountered in GSM networks */ static void sdp_add_all_mobile_codecs(struct sdp_audio_codecs *ac) { /* In order of preference. TODO: make configurable */ static const enum gsm48_bcap_speech_ver mobile_codecs[] = { GSM48_BCAP_SV_AMR_F /*!< 4 GSM FR V3 (FR AMR) */, GSM48_BCAP_SV_AMR_H /*!< 5 GSM HR V3 (HR_AMR) */, GSM48_BCAP_SV_EFR /*!< 2 GSM FR V2 (GSM EFR) */, GSM48_BCAP_SV_FR /*!< 0 GSM FR V1 (GSM FR) */, GSM48_BCAP_SV_HR /*!< 1 GSM HR V1 (GSM HR) */, }; int i; for (i = 0; i < ARRAY_SIZE(mobile_codecs); i++) sdp_audio_codecs_add_speech_ver(ac, mobile_codecs[i]); } /* Add all known AMR payload types encountered in UTRAN networks */ static void sdp_add_all_utran_codecs(struct sdp_audio_codecs *ac) { /* In order of preference. TODO: make configurable */ static const enum gsm48_bcap_speech_ver utran_codecs[] = { GSM48_BCAP_SV_AMR_F /*!< 4 GSM FR V3 (FR AMR) */, GSM48_BCAP_SV_AMR_H /*!< 5 GSM HR V3 (HR_AMR) */, GSM48_BCAP_SV_AMR_OH /*!< 11 GSM HR V6 (OHR AMR) */, GSM48_BCAP_SV_AMR_FW /*!< 8 GSM FR V5 (FR AMR-WB) */, GSM48_BCAP_SV_AMR_OFW /*!< 6 GSM FR V4 (OFR AMR-WB) */, GSM48_BCAP_SV_AMR_OHW /*!< 7 GSM HR V4 (OHR AMR-WB) */, }; int i; for (i = 0; i < ARRAY_SIZE(utran_codecs); i++) sdp_audio_codecs_add_speech_ver(ac, utran_codecs[i]); } void codec_filter_init(struct codec_filter *codec_filter) { *codec_filter = (struct codec_filter){}; } void codec_filter_set_ran(struct codec_filter *codec_filter, enum osmo_rat_type ran_type) { codec_filter->ran = (struct sdp_audio_codecs){}; switch (ran_type) { default: case OSMO_RAT_GERAN_A: sdp_add_all_mobile_codecs(&codec_filter->ran); break; case OSMO_RAT_UTRAN_IU: sdp_add_all_utran_codecs(&codec_filter->ran); break; } } void codec_filter_set_ms_from_bc(struct codec_filter *codec_filter, const struct gsm_mncc_bearer_cap *ms_bearer_cap) { codec_filter->ms = (struct sdp_audio_codecs){0}; if (ms_bearer_cap) sdp_audio_codecs_from_bearer_cap(&codec_filter->ms, ms_bearer_cap); } 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); } int codec_filter_set_remote(struct codec_filter *codec_filter, const char *remote_sdp) { return sdp_msg_from_sdp_str(&codec_filter->remote, remote_sdp); } void codec_filter_set_local_rtp(struct codec_filter *codec_filter, const struct osmo_sockaddr_str *rtp) { if (!rtp) codec_filter->result.rtp = (struct osmo_sockaddr_str){0}; else codec_filter->result.rtp = *rtp; } /* 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_audio_codecs *r = &codec_filter->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 (codec_filter->remote.audio_codecs.count) sdp_audio_codecs_intersection(r, &codec_filter->remote.audio_codecs, true); #if ALLOW_REASSIGNMENT /* If osmo-msc were able to trigger a re-assignment after the remote side has picked a codec mismatching the * initial Assignment, then this code here would make sense: keep the other codecs as available to choose from, * but put the currently assigned codec in the first position. */ if (sdp_audio_codec_is_set(a)) { /* Assignment has completed, the chosen codec should be the first of the resulting SDP. * Make sure this is actually listed in the result SDP and move to first place. */ struct sdp_audio_codec *select = sdp_audio_codec_by_descr(r, a); if (!select) { /* Not present. Add. */ if (sdp_audio_codec_by_payload_type(r, a->payload_type, false)) { /* Oh crunch, that payload type number is already in use. * Find an unused one. */ for (a->payload_type = 96; a->payload_type <= 127; a->payload_type++) { if (!sdp_audio_codec_by_payload_type(r, a->payload_type, false)) break; } if (a->payload_type > 127) return -ENOSPC; } select = sdp_audio_codec_add_copy(r, a); } sdp_audio_codecs_select(r, select); } #else /* Currently, osmo-msc does not trigger re-assignment if the remote side has picked a codec that the local side * would also support, but the local side has already assigned a mismatching codec before. Mismatching codecs * means call failure. So, currently, if locally, Assignment has already happened, it makes sense to send only * the assigned codec as available choice to the remote side. */ if (sdp_audio_codec_is_set(a)) { /* Assignment has completed, the chosen codec should be the the only possible one. */ struct sdp_audio_codecs assigned_codec = {}; sdp_audio_codecs_add_copy(&assigned_codec, a); sdp_audio_codecs_intersection(r, &assigned_codec, false); } #endif return 0; } int codec_filter_to_str_buf(char *buf, size_t buflen, const struct codec_filter *codec_filter) { struct osmo_strbuf sb = { .buf = buf, .len = buflen }; OSMO_STRBUF_PRINTF(sb, "RAN={"); OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ran); 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, "}"); } 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->remote.audio_codecs.count || osmo_sockaddr_str_is_nonzero(&codec_filter->remote.rtp)) { OSMO_STRBUF_PRINTF(sb, " remote="); OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, &codec_filter->remote); } 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); } OSMO_STRBUF_PRINTF(sb, " result="); OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, &codec_filter->result); return sb.chars_needed; } char *codec_filter_to_str_c(void *ctx, const struct codec_filter *codec_filter) { OSMO_NAME_C_IMPL(ctx, 128, "codec_filter_to_str_c-ERROR", codec_filter_to_str_buf, codec_filter) } const char *codec_filter_to_str(const struct codec_filter *codec_filter) { return codec_filter_to_str_c(OTC_SELECT, codec_filter); }