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osmo-bsc/src/osmo-bsc/codec_pref.c

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/*
* (C) 2017-2018 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
* All Rights Reserved
*
* Author: Philipp Maier
*
* 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/core/msgb.h>
#include <osmocom/mgcp_client/mgcp_client_fsm.h>
#include <osmocom/netif/rtp.h>
#include <osmocom/gsm/protocol/gsm_08_08.h>
#include <osmocom/gsm/gsm0808_utils.h>
#include <osmocom/bsc/bsc_msc_data.h>
#include <osmocom/bsc/codec_pref.h>
#include <osmocom/bsc/gsm_data.h>
#include <osmocom/bsc/bts.h>
/* Determine whether a permitted speech value is specifies a half rate or full
* rate codec */
static int full_rate_from_perm_spch(bool * full_rate,
enum gsm0808_permitted_speech perm_spch)
{
/* Check if the result is a half or full rate codec */
switch (perm_spch) {
case GSM0808_PERM_HR1:
case GSM0808_PERM_HR2:
case GSM0808_PERM_HR3:
case GSM0808_PERM_HR4:
case GSM0808_PERM_HR6:
*full_rate = false;
break;
case GSM0808_PERM_FR1:
case GSM0808_PERM_FR2:
case GSM0808_PERM_FR3:
case GSM0808_PERM_FR4:
case GSM0808_PERM_FR5:
*full_rate = true;
break;
default:
LOGP(DMSC, LOGL_ERROR, "Invalid permitted-speech value: %u\n",
perm_spch);
return -EINVAL;
}
return 0;
}
/* Look up a matching chan mode for a given permitted speech value */
static enum gsm48_chan_mode gsm88_to_chan_mode(enum gsm0808_permitted_speech speech)
{
switch (speech) {
case GSM0808_PERM_HR1:
case GSM0808_PERM_FR1:
return GSM48_CMODE_SPEECH_V1;
break;
case GSM0808_PERM_FR2:
return GSM48_CMODE_SPEECH_EFR;
break;
case GSM0808_PERM_HR3:
case GSM0808_PERM_FR3:
return GSM48_CMODE_SPEECH_AMR;
break;
case GSM0808_PERM_HR2:
LOGP(DMSC, LOGL_FATAL, "Speech HR2 was never specified!\n");
/* fall through */
default:
LOGP(DMSC, LOGL_FATAL, "Unsupported permitted speech %s selected, "
"assuming AMR as channel mode...\n",
gsm0808_permitted_speech_name(speech));
return GSM48_CMODE_SPEECH_AMR;
}
}
/* Look up a matching permitted speech value for a given msc audio codec pref */
static enum gsm0808_permitted_speech audio_support_to_gsm88(const struct gsm_audio_support *audio)
{
if (audio->hr) {
switch (audio->ver) {
case 1:
return GSM0808_PERM_HR1;
break;
case 2:
return GSM0808_PERM_HR2;
break;
case 3:
return GSM0808_PERM_HR3;
break;
default:
LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: hr%d, using hr1 instead\n", audio->ver);
return GSM0808_PERM_HR1;
}
} else {
switch (audio->ver) {
case 1:
return GSM0808_PERM_FR1;
break;
case 2:
return GSM0808_PERM_FR2;
break;
case 3:
return GSM0808_PERM_FR3;
break;
default:
LOGP(DMSC, LOGL_ERROR, "Wrong speech mode: fr%d, using fr1 instead\n", audio->ver);
return GSM0808_PERM_FR1;
}
}
}
/* Test if a given audio support matches one of the permitted speech settings
* of the channel type element. The matched permitted speech value is then also
* compared against the speech codec list. (optional, only relevant for AoIP) */
static bool test_codec_pref(const struct gsm0808_speech_codec **sc_match,
const struct gsm0808_speech_codec_list *scl,
const struct gsm0808_channel_type *ct,
uint8_t perm_spch)
{
unsigned int i;
bool match = false;
struct gsm0808_speech_codec sc;
int rc;
*sc_match = NULL;
/* Try to find the given permitted speech value in the
* codec list of the channel type element */
for (i = 0; i < ct->perm_spch_len; i++) {
if (ct->perm_spch[i] == perm_spch) {
match = true;
break;
}
}
/* If we do not have a speech codec list to test against,
* we just exit early (will be always the case in non-AoIP networks) */
if (!scl || !scl->len)
return match;
/* If we failed to match until here, there is no
* point in testing further */
if (match == false)
return false;
/* Extrapolate speech codec data */
rc = gsm0808_speech_codec_from_chan_type(&sc, perm_spch);
if (rc < 0)
return false;
/* Try to find extrapolated speech codec data in
* the speech codec list */
for (i = 0; i < scl->len; i++) {
if (sc.type == scl->codec[i].type) {
*sc_match = &scl->codec[i];
return true;
}
}
return false;
}
static bool test_codec_support_bts_rate(const struct gsm_bts *bts, const bool full_rate)
{
unsigned int i;
struct gsm_bts_trx *trx;
llist_for_each_entry(trx, &bts->trx_list, list) {
for (i = 0; i < TRX_NR_TS; i++) {
switch (trx->ts[i].pchan_from_config) {
case GSM_PCHAN_OSMO_DYN:
return true;
case GSM_PCHAN_TCH_F:
case GSM_PCHAN_TCH_F_PDCH:
if (full_rate)
return true;
break;
case GSM_PCHAN_TCH_H:
if (!full_rate)
return true;
break;
default:
continue;
}
}
}
return false;
}
/* Check if the given permitted speech value is supported by the BTS
* (vty option bts->codec-support). */
static bool test_codec_support_bts(const struct gsm_bts *bts, uint8_t perm_spch)
{
const struct bts_codec_conf *bts_codec = &bts->codec;
bool full_rate;
int rc;
/* Check if the BTS provides a physical channel that matches the
* bandwidth of the desired codec. */
rc = full_rate_from_perm_spch(&full_rate, perm_spch);
if (rc < 0)
return false;
if (!test_codec_support_bts_rate(bts, full_rate))
return false;
/* Check codec support */
switch (perm_spch) {
case GSM0808_PERM_FR1:
/* GSM-FR is always supported by all BTSs. There is also no way to
* selectively disable GSM-RF per BTS via VTY. */
return true;
case GSM0808_PERM_FR2:
return (bool)bts_codec->efr;
case GSM0808_PERM_FR3:
case GSM0808_PERM_HR3:
return (bool)bts_codec->amr;
case GSM0808_PERM_HR1:
return (bool)bts_codec->hr;
default:
return false;
}
return false;
}
/* Generate the bss supported amr configuration bits (S0-S15) */
static uint16_t gen_bss_supported_amr_s15_s0(const struct bsc_msc_data *msc, const struct gsm_bts *bts, bool hr)
{
const struct gsm48_multi_rate_conf *amr_cfg_bts;
const struct gsm48_multi_rate_conf *amr_cfg_msc;
uint16_t amr_s15_s0_bts;
uint16_t amr_s15_s0_msc;
/* Lookup the BTS specific AMR rate configuration. This config is set
* via the VTY for each BTS individually. In cases where no configuration
* is set we will assume a safe default */
if (hr) {
amr_cfg_bts = (struct gsm48_multi_rate_conf *)&bts->mr_half.gsm48_ie;
amr_s15_s0_bts = gsm0808_sc_cfg_from_gsm48_mr_cfg(amr_cfg_bts, false);
} else {
amr_cfg_bts = (struct gsm48_multi_rate_conf *)&bts->mr_full.gsm48_ie;
amr_s15_s0_bts = gsm0808_sc_cfg_from_gsm48_mr_cfg(amr_cfg_bts, true);
}
/* Lookup the AMR rate configuration that is set for the MSC */
amr_cfg_msc = &msc->amr_conf;
amr_s15_s0_msc = gsm0808_sc_cfg_from_gsm48_mr_cfg(amr_cfg_msc, true);
/* Calculate the intersection of the two configurations and update S0-S15
* in the codec list. */
return amr_s15_s0_bts & amr_s15_s0_msc;
}
/* Special handling for AMR rate configuration bits (S15-S0) */
static int match_amr_s15_s0(struct channel_mode_and_rate *ch_mode_rate, const struct bsc_msc_data *msc, const struct gsm_bts *bts, const struct gsm0808_speech_codec *sc_match, uint8_t perm_spch)
{
uint16_t amr_s15_s0_supported;
/* Normally the MSC should never try to advertise an AMR codec
* configuration that we did not previously advertised as supported.
* However, to ensure that no unsupported AMR codec configuration
* enters the further processing steps we again lookup what we support
* and generate an intersection. All further processing is then done
* with this intersection result. At the same time we will make sure
* that the intersection contains at least one rate setting. */
amr_s15_s0_supported = gen_bss_supported_amr_s15_s0(msc, bts, (perm_spch == GSM0808_PERM_HR3));
/* NOTE: The sc_match pointer points to a speech codec from the speech
* codec list that has been communicated with the ASSIGNMENT COMMAND.
* However, only AoIP based networks will include a speech codec list
* into the ASSIGNMENT COMMAND. For non AoIP based networks, no speech
* codec (sc_match) will be available, so we will fully rely on the
* local configuration for those cases. */
if (sc_match)
ch_mode_rate->s15_s0 = sc_match->cfg & amr_s15_s0_supported;
else
ch_mode_rate->s15_s0 = amr_s15_s0_supported;
/* Prefer "Config-NB-Code = 1" (S1) over all other AMR rates settings.
* When S1 is set, the active set will automatically include 12.2k, 7.4k,
* 5.9k, 4.75k, in case of HR 12,2k is left out. */
if (ch_mode_rate->s15_s0 & GSM0808_SC_CFG_AMR_4_75_5_90_7_40_12_20) {
ch_mode_rate->s15_s0 &= 0xff00;
ch_mode_rate->s15_s0 |= GSM0808_SC_CFG_AMR_4_75_5_90_7_40_12_20;
}
/* Make sure at least one rate is set. */
if ((ch_mode_rate->s15_s0 & 0x00ff) == 0x0000)
return -EINVAL;
return 0;
}
/*! Match the codec preferences from local config with codec preference IEs
* received from the MSC and the BTS' codec configuration.
* \param[out] ch_mode_rate resulting codec and rate information
* \param[in] ct GSM 08.08 channel type received from MSC.
* \param[in] scl GSM 08.08 speech codec list received from MSC (optional).
* \param[in] msc associated msc (current codec settings).
* \param[in] bts associated bts (current codec settings).
* \param[in] pref selected rate preference (full, half or none).
* \returns 0 on success, -1 in case no match was found */
int match_codec_pref(struct channel_mode_and_rate *ch_mode_rate,
const struct gsm0808_channel_type *ct,
const struct gsm0808_speech_codec_list *scl,
const struct bsc_msc_data *msc,
const struct gsm_bts *bts, enum rate_pref rate_pref)
{
unsigned int i;
uint8_t perm_spch;
bool full_rate;
bool match = false;
const struct gsm0808_speech_codec *sc_match = NULL;
int rc;
/* Note: Normally the MSC should never try to advertise a codec that
* we did not advertise as supported before. In order to ensure that
* no unsupported codec is accepted, we make sure that the codec is
* indeed available with the current BTS and MSC configuration */
for (i = 0; i < msc->audio_length; i++) {
/* Pick a permitted speech value from the global codec configuration list */
perm_spch = audio_support_to_gsm88(&msc->audio_support[i]);
/* Determine if the result is a half or full rate codec */
rc = full_rate_from_perm_spch(&full_rate, perm_spch);
if (rc < 0)
return -EINVAL;
ch_mode_rate->chan_rate = full_rate ? CH_RATE_FULL : CH_RATE_HALF;
/* If we have a preference for FR or HR in our request, we
* discard the potential match */
if (rate_pref == RATE_PREF_HR && ch_mode_rate->chan_rate == CH_RATE_FULL)
continue;
if (rate_pref == RATE_PREF_FR && ch_mode_rate->chan_rate == CH_RATE_HALF)
continue;
/* Check this permitted speech value against the BTS specific parameters.
* if the BTS does not support the codec, try the next one */
if (!test_codec_support_bts(bts, perm_spch))
continue;
/* Match the permitted speech value against the codec lists that were
* advertised by the MS and the MSC */
if (!test_codec_pref(&sc_match, scl, ct, perm_spch)) {
continue;
}
/* Special handling for AMR */
if (perm_spch == GSM0808_PERM_HR3 || perm_spch == GSM0808_PERM_FR3) {
rc = match_amr_s15_s0(ch_mode_rate, msc, bts, sc_match, perm_spch);
if (rc < 0) {
ch_mode_rate->s15_s0 = 0;
continue;
}
} else
ch_mode_rate->s15_s0 = 0;
match = true;
break;
}
/* Exit without result, in case no match can be detected */
if (!match) {
ch_mode_rate->chan_mode = GSM48_CMODE_SIGN;
ch_mode_rate->chan_rate = CH_RATE_SDCCH;
ch_mode_rate->s15_s0 = 0;
return -1;
}
/* Lookup a channel mode for the selected codec */
ch_mode_rate->chan_mode = gsm88_to_chan_mode(perm_spch);
return 0;
}
/*! Determine the BSS supported speech codec list that is sent to the MSC with
* the COMPLETE LAYER 3 INFORMATION message.
* \param[out] scl GSM 08.08 speech codec list with BSS supported codecs.
* \param[in] msc associated msc (current codec settings).
* \param[in] bts associated bts (current codec settings). */
void gen_bss_supported_codec_list(struct gsm0808_speech_codec_list *scl,
const struct bsc_msc_data *msc, const struct gsm_bts *bts)
{
uint8_t perm_spch;
unsigned int i;
int rc;
memset(scl, 0, sizeof(*scl));
for (i = 0; i < msc->audio_length; i++) {
/* Pick a permitted speech value from the global codec configuration list */
perm_spch = audio_support_to_gsm88(&msc->audio_support[i]);
/* Check this permitted speech value against the BTS specific parameters.
* if the BTS does not support the codec, try the next one */
if (!test_codec_support_bts(bts, perm_spch))
continue;
/* Write item into codec list */
rc = gsm0808_speech_codec_from_chan_type(&scl->codec[scl->len], perm_spch);
if (rc != 0)
continue;
/* AMR (HR/FR version 3) is the only codec that requires a codec
* configuration (S0-S15). Determine the current configuration and update
* the cfg flag. */
if (msc->audio_support[i].ver == 3)
scl->codec[scl->len].cfg = gen_bss_supported_amr_s15_s0(msc, bts, msc->audio_support[i].hr);
scl->len++;
}
}
/*! Calculate the intersection of the rate configuration of two multirate configuration
* IE structures. The result c will be a copy of a, but the rate configuration bits
* will be the intersection of the rate configuration bits in a and b.
* \param[out] c user provided memory to store the result.
* \param[in] a multi rate configuration a.
* \param[in] b multi rate configuration b.
* \returns 0 on success, -1 when the result contains an empty set of modes. */
int calc_amr_rate_intersection(struct gsm48_multi_rate_conf *c,
const struct gsm48_multi_rate_conf *b,
const struct gsm48_multi_rate_conf *a)
{
struct gsm48_multi_rate_conf res;
uint8_t *_a = (uint8_t *) a;
uint8_t *_b = (uint8_t *) b;
uint8_t *_res = (uint8_t *) & res;
memcpy(&res, a, sizeof(res));
_res[1] = _a[1] & _b[1];
if (_res[1] == 0x00)
return -1;
if (c)
memcpy(c, &res, sizeof(*c));
return 0;
}
/*! Visit the codec settings for the MSC and for each BTS in order to make sure
* that the configuration does not contain any combinations that lead into a
* mutually exclusive codec configuration (empty intersection).
* \param[in] mscs list head of the msc list.
* \returns 0 on success, -1 in case an invalid setting is found. */
int check_codec_pref(struct llist_head *mscs)
{
struct bsc_msc_data *msc;
struct gsm_bts *bts;
struct gsm0808_speech_codec_list scl;
int rc = 0;
int rc_rate;
const struct gsm48_multi_rate_conf *bts_gsm48_ie;
llist_for_each_entry(msc, mscs, entry) {
llist_for_each_entry(bts, &msc->network->bts_list, list) {
gen_bss_supported_codec_list(&scl, msc, bts);
if (scl.len <= 0) {
LOGP(DMSC, LOGL_FATAL,
"codec-support/trx config of BTS %u does not intersect with codec-list of MSC %u\n",
bts->nr, msc->nr);
rc = -1;
}
/* Full rate codec check, only if any full rate TS is configured. */
if (test_codec_support_bts_rate(bts, true)) {
bts_gsm48_ie = (struct gsm48_multi_rate_conf *)&bts->mr_full.gsm48_ie;
rc_rate = calc_amr_rate_intersection(NULL, &msc->amr_conf, bts_gsm48_ie);
if (rc_rate < 0) {
LOGP(DMSC, LOGL_FATAL,
"network amr tch-f mode config of BTS %u does not intersect with amr-config of MSC %u\n",
bts->nr, msc->nr);
rc = -1;
}
}
/* Half rate codec check, only if any half rate TS is configured. */
if (test_codec_support_bts_rate(bts, false)) {
bts_gsm48_ie = (struct gsm48_multi_rate_conf *)&bts->mr_half.gsm48_ie;
rc_rate = calc_amr_rate_intersection(NULL, &msc->amr_conf, bts_gsm48_ie);
if (rc_rate < 0) {
LOGP(DMSC, LOGL_FATAL,
"network amr tch-h mode config of BTS %u does not intersect with amr-config of MSC %u\n",
bts->nr, msc->nr);
rc = -1;
}
}
}
}
return rc;
}
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