Neels Hofmeyr | 63881a3 | 2022-01-13 18:34:52 +0100 | [diff] [blame] | 1 | /* Filter/overlay codec selections for a voice call, across MS, RAN and CN limitations */ |
| 2 | /* |
Vadim Yanitskiy | 999a593 | 2023-05-18 17:22:26 +0700 | [diff] [blame] | 3 | * (C) 2019-2023 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de> |
Neels Hofmeyr | 63881a3 | 2022-01-13 18:34:52 +0100 | [diff] [blame] | 4 | * All Rights Reserved |
| 5 | * |
| 6 | * Author: Neels Hofmeyr |
| 7 | * |
| 8 | * SPDX-License-Identifier: AGPL-3.0+ |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify |
| 11 | * it under the terms of the GNU Affero General Public License as published by |
| 12 | * the Free Software Foundation; either version 3 of the License, or |
| 13 | * (at your option) any later version. |
| 14 | * |
| 15 | * This program is distributed in the hope that it will be useful, |
| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | * GNU Affero General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU Affero General Public License |
| 21 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 22 | */ |
| 23 | |
| 24 | #include <osmocom/gsm/protocol/gsm_08_08.h> |
| 25 | |
| 26 | #include <osmocom/msc/codec_filter.h> |
| 27 | #include <osmocom/msc/codec_mapping.h> |
| 28 | #include <osmocom/msc/debug.h> |
| 29 | |
| 30 | /* Add all known payload types encountered in GSM networks */ |
| 31 | static void sdp_add_all_geran_codecs(struct sdp_audio_codecs *ac) |
| 32 | { |
| 33 | /* In order of preference. TODO: make configurable */ |
| 34 | static const enum gsm48_bcap_speech_ver mobile_codecs[] = { |
| 35 | GSM48_BCAP_SV_AMR_F /*!< 4 GSM FR V3 (FR AMR) */, |
| 36 | GSM48_BCAP_SV_AMR_H /*!< 5 GSM HR V3 (HR_AMR) */, |
| 37 | GSM48_BCAP_SV_EFR /*!< 2 GSM FR V2 (GSM EFR) */, |
| 38 | GSM48_BCAP_SV_FR /*!< 0 GSM FR V1 (GSM FR) */, |
| 39 | GSM48_BCAP_SV_HR /*!< 1 GSM HR V1 (GSM HR) */, |
| 40 | }; |
| 41 | int i; |
| 42 | for (i = 0; i < ARRAY_SIZE(mobile_codecs); i++) |
| 43 | sdp_audio_codecs_add_speech_ver(ac, mobile_codecs[i]); |
| 44 | } |
| 45 | |
| 46 | /* Add all known AMR payload types encountered in UTRAN networks */ |
| 47 | static void sdp_add_all_utran_codecs(struct sdp_audio_codecs *ac) |
| 48 | { |
| 49 | /* In order of preference. TODO: make configurable */ |
| 50 | static const enum gsm48_bcap_speech_ver utran_codecs[] = { |
| 51 | GSM48_BCAP_SV_AMR_F /*!< 4 GSM FR V3 (FR AMR) */, |
| 52 | GSM48_BCAP_SV_AMR_H /*!< 5 GSM HR V3 (HR_AMR) */, |
| 53 | GSM48_BCAP_SV_AMR_OH /*!< 11 GSM HR V6 (OHR AMR) */, |
| 54 | GSM48_BCAP_SV_AMR_FW /*!< 8 GSM FR V5 (FR AMR-WB) */, |
| 55 | GSM48_BCAP_SV_AMR_OFW /*!< 6 GSM FR V4 (OFR AMR-WB) */, |
| 56 | GSM48_BCAP_SV_AMR_OHW /*!< 7 GSM HR V4 (OHR AMR-WB) */, |
| 57 | }; |
| 58 | int i; |
| 59 | for (i = 0; i < ARRAY_SIZE(utran_codecs); i++) |
| 60 | sdp_audio_codecs_add_speech_ver(ac, utran_codecs[i]); |
| 61 | } |
| 62 | |
| 63 | void codec_filter_init(struct codec_filter *codec_filter) |
| 64 | { |
| 65 | *codec_filter = (struct codec_filter){}; |
| 66 | } |
| 67 | |
| 68 | void codec_filter_set_ran(struct codec_filter *codec_filter, enum osmo_rat_type ran_type) |
| 69 | { |
| 70 | codec_filter->ran = (struct sdp_audio_codecs){}; |
| 71 | |
| 72 | switch (ran_type) { |
| 73 | default: |
| 74 | case OSMO_RAT_GERAN_A: |
| 75 | sdp_add_all_geran_codecs(&codec_filter->ran); |
| 76 | break; |
| 77 | |
| 78 | case OSMO_RAT_UTRAN_IU: |
| 79 | sdp_add_all_utran_codecs(&codec_filter->ran); |
| 80 | break; |
| 81 | } |
| 82 | } |
| 83 | |
Neels Hofmeyr | 63881a3 | 2022-01-13 18:34:52 +0100 | [diff] [blame] | 84 | void codec_filter_set_bss(struct codec_filter *codec_filter, |
| 85 | const struct gsm0808_speech_codec_list *codec_list_bss_supported) |
| 86 | { |
| 87 | codec_filter->bss = (struct sdp_audio_codecs){}; |
| 88 | if (codec_list_bss_supported) |
| 89 | sdp_audio_codecs_from_speech_codec_list(&codec_filter->bss, codec_list_bss_supported); |
| 90 | } |
| 91 | |
| 92 | int codec_filter_set_remote(struct codec_filter *codec_filter, const char *remote_sdp) |
| 93 | { |
| 94 | return sdp_msg_from_sdp_str(&codec_filter->remote, remote_sdp); |
| 95 | } |
| 96 | |
| 97 | void codec_filter_set_local_rtp(struct codec_filter *codec_filter, const struct osmo_sockaddr_str *rtp) |
| 98 | { |
| 99 | if (!rtp) |
| 100 | codec_filter->result.rtp = (struct osmo_sockaddr_str){0}; |
| 101 | else |
| 102 | codec_filter->result.rtp = *rtp; |
| 103 | } |
| 104 | |
| 105 | /* Render intersections of all known audio codec constraints to reach a resulting choice of favorite audio codec, plus |
| 106 | * possible set of alternative audio codecs, in codec_filter->result. (The result.rtp address remains unchanged.) */ |
| 107 | int codec_filter_run(struct codec_filter *codec_filter) |
| 108 | { |
| 109 | struct sdp_audio_codecs *r = &codec_filter->result.audio_codecs; |
| 110 | struct sdp_audio_codec *a = &codec_filter->assignment; |
| 111 | *r = codec_filter->ran; |
| 112 | if (codec_filter->ms.count) |
| 113 | sdp_audio_codecs_intersection(r, &codec_filter->ms, false); |
| 114 | if (codec_filter->bss.count) |
| 115 | sdp_audio_codecs_intersection(r, &codec_filter->bss, false); |
| 116 | if (codec_filter->remote.audio_codecs.count) |
| 117 | sdp_audio_codecs_intersection(r, &codec_filter->remote.audio_codecs, true); |
| 118 | |
| 119 | #if 0 |
| 120 | /* Future: If osmo-msc were able to trigger a re-assignment after the remote side has picked a codec mismatching |
| 121 | * the initial Assignment, then this code here would make sense: keep the other codecs as available to choose |
| 122 | * from, but put the currently assigned codec in the first position. So far we only offer the single assigned |
| 123 | * codec, because we have no way to deal with the remote side picking a different codec. |
| 124 | * Another approach would be to postpone assignment until we know the codecs from the remote side. */ |
| 125 | if (sdp_audio_codec_is_set(a)) { |
| 126 | /* Assignment has completed, the chosen codec should be the first of the resulting SDP. |
| 127 | * Make sure this is actually listed in the result SDP and move to first place. */ |
| 128 | struct sdp_audio_codec *select = sdp_audio_codecs_by_descr(r, a); |
| 129 | |
| 130 | if (!select) { |
| 131 | /* Not present. Add. */ |
| 132 | if (sdp_audio_codec_by_payload_type(r, a->payload_type, false)) { |
| 133 | /* Oh crunch, that payload type number is already in use. |
| 134 | * Find an unused one. */ |
| 135 | for (a->payload_type = 96; a->payload_type <= 127; a->payload_type++) { |
| 136 | if (!sdp_audio_codec_by_payload_type(r, a->payload_type, false)) |
| 137 | break; |
| 138 | } |
| 139 | |
| 140 | if (a->payload_type > 127) |
| 141 | return -ENOSPC; |
| 142 | } |
| 143 | select = sdp_audio_codecs_add_copy(r, a); |
| 144 | } |
| 145 | |
| 146 | sdp_audio_codecs_select(r, select); |
| 147 | } |
| 148 | #else |
| 149 | /* Currently, osmo-msc does not trigger re-assignment if the remote side has picked a codec that is different |
| 150 | * from the already assigned codec. |
| 151 | * So, if locally, Assignment has already chosen a codec, this is the single definitive result to be used |
| 152 | * towards the CN. */ |
| 153 | if (sdp_audio_codec_is_set(a)) { |
| 154 | /* Assignment has completed, the chosen codec should be the the only possible one. */ |
| 155 | *r = (struct sdp_audio_codecs){}; |
| 156 | sdp_audio_codecs_add_copy(r, a); |
| 157 | } |
| 158 | #endif |
| 159 | return 0; |
| 160 | } |
| 161 | |
| 162 | int codec_filter_to_str_buf(char *buf, size_t buflen, const struct codec_filter *codec_filter) |
| 163 | { |
| 164 | struct osmo_strbuf sb = { .buf = buf, .len = buflen }; |
| 165 | OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, &codec_filter->result); |
| 166 | OSMO_STRBUF_PRINTF(sb, " (from:"); |
| 167 | |
| 168 | if (sdp_audio_codec_is_set(&codec_filter->assignment)) { |
| 169 | OSMO_STRBUF_PRINTF(sb, " assigned="); |
| 170 | OSMO_STRBUF_APPEND(sb, sdp_audio_codec_to_str_buf, &codec_filter->assignment); |
| 171 | } |
| 172 | |
| 173 | if (codec_filter->remote.audio_codecs.count |
| 174 | || osmo_sockaddr_str_is_nonzero(&codec_filter->remote.rtp)) { |
| 175 | OSMO_STRBUF_PRINTF(sb, " remote="); |
| 176 | OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, &codec_filter->remote); |
| 177 | } |
| 178 | |
| 179 | if (codec_filter->ms.count) { |
| 180 | OSMO_STRBUF_PRINTF(sb, " MS={"); |
| 181 | OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ms); |
| 182 | OSMO_STRBUF_PRINTF(sb, "}"); |
| 183 | } |
| 184 | |
| 185 | if (codec_filter->bss.count) { |
| 186 | OSMO_STRBUF_PRINTF(sb, " bss={"); |
| 187 | OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->bss); |
| 188 | OSMO_STRBUF_PRINTF(sb, "}"); |
| 189 | } |
| 190 | |
| 191 | OSMO_STRBUF_PRINTF(sb, " RAN={"); |
| 192 | OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ran); |
| 193 | OSMO_STRBUF_PRINTF(sb, "}"); |
| 194 | |
| 195 | OSMO_STRBUF_PRINTF(sb, ")"); |
| 196 | |
| 197 | return sb.chars_needed; |
| 198 | } |
| 199 | |
| 200 | char *codec_filter_to_str_c(void *ctx, const struct codec_filter *codec_filter) |
| 201 | { |
| 202 | OSMO_NAME_C_IMPL(ctx, 128, "codec_filter_to_str_c-ERROR", codec_filter_to_str_buf, codec_filter) |
| 203 | } |
| 204 | |
| 205 | const char *codec_filter_to_str(const struct codec_filter *codec_filter) |
| 206 | { |
| 207 | return codec_filter_to_str_c(OTC_SELECT, codec_filter); |
| 208 | } |