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[codecs filter] MT call: apply remote call leg codecs 

Use either the SDP or the Bearer Capabilites indicated in the incoming
MNCC to apply the remote call leg's codecs selection to the codecs
filter. Use the codecs filter result for outgoing Bearer Capabilites.

So far, we just forwarded the Bearer Capabilities received in MNCC from
the remote call leg, and omitted Bearer Cap if the remote call leg did
not provide any.

Instead, always include Bearer Cap, and compose it from the codecs
filter result. Hence the Bearer Cap is now an intersection of MS, BSS
and remote call leg, instead of just the remote call leg.

Related: SYS#5066
Change-Id: I84d9bbca3e4061da622b1b2fc0bde8868e7e3521
This commit is contained in:
Neels Hofmeyr 2022-01-13 21:40:58 +01:00
parent fabe49c431
commit 230389adea
3 changed files with 64 additions and 11 deletions
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61
src/libmsc/gsm_04_08_cc.c
View File

@ -639,6 +639,7 @@ static int gsm48_cc_tx_setup(struct gsm_trans *trans, void *arg)
struct gsm48_hdr *gh;
struct gsm_mncc *setup = arg;
int rc, trans_id;
struct gsm_mncc_bearer_cap bearer_cap;
gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
@ -683,14 +684,60 @@ static int gsm48_cc_tx_setup(struct gsm_trans *trans, void *arg)
codec_filter_init(&trans->cc.codecs);
codec_filter_set_ran(&trans->cc.codecs, trans->msc_a->c.ran->type);
codec_filter_set_bss(&trans->cc.codecs, &trans->msc_a->cc.compl_l3_codec_list_bss_supported);
/* bearer capability */
if (setup->fields & MNCC_F_BEARER_CAP) {
/* Create a copy of the bearer capability in the transaction struct, so we
* can use this information later */
memcpy(&trans->bearer_cap, &setup->bearer_cap, sizeof(trans->bearer_cap));
gsm48_encode_bearer_cap(msg, 0, &setup->bearer_cap);
/* sdp.remote: if SDP is included in the MNCC, take that as definitive list of remote audio codecs. */
if (setup->sdp[0]) {
rc = sdp_msg_from_sdp_str(&trans->cc.codecs.remote, setup->sdp);
if (rc)
LOG_TRANS(trans, LOGL_ERROR, "Failed to parse remote call leg SDP: %d\n", rc);
}
/* sdp.remote: if there is no SDP information or we failed to parse it, try using the Bearer Capability from
* MNCC, if any. */
if (!trans->cc.codecs.remote.audio_codecs.count && (setup->fields & MNCC_F_BEARER_CAP)) {
trans->cc.codecs.remote = (struct sdp_msg){};
sdp_audio_codecs_from_bearer_cap(&trans->cc.codecs.remote.audio_codecs,
&setup->bearer_cap);
}
LOG_TRANS(trans, LOGL_DEBUG, "codecs: %s\n", codec_filter_to_str(&trans->cc.codecs));
if (!trans->cc.codecs.remote.audio_codecs.count)
LOG_TRANS(trans, LOGL_INFO,
"Got no information of remote audio codecs: neither SDP nor Bearer Capability. Trying anyway.\n");
codec_filter_run(&trans->cc.codecs);
LOG_TRANS(trans, LOGL_DEBUG, "codecs: %s\n", codec_filter_to_str(&trans->cc.codecs));
/* Compose Bearer Capability information that reflects only the codecs (Speech Versions) remaining after
* intersecting MS, BSS and remote call leg restrictions. To store in trans for later use, and to include in
* the outgoing CC Setup message. */
bearer_cap = (struct gsm_mncc_bearer_cap){
.speech_ver = { -1 },
};
sdp_audio_codecs_to_bearer_cap(&bearer_cap, &trans->cc.codecs.result.audio_codecs);
rc = bearer_cap_set_radio(&bearer_cap);
if (rc) {
LOG_TRANS(trans, LOGL_ERROR, "Error composing Bearer Capability for CC Setup\n");
trans_free(trans);
msgb_free(msg);
return rc;
}
/* Create a copy of the bearer capability in the transaction struct, so we can use this information later */
trans->bearer_cap = bearer_cap;
/* If no resulting codecs remain, error out. We cannot find a codec that matches both call legs. If the MGW were
* able to transcode, we could use non-identical codecs on each conn of the MGW endpoint, but we are aiming for
* finding a matching codec. */
if (bearer_cap.speech_ver[0] == -1) {
LOG_TRANS(trans, LOGL_ERROR, "%s: no codec match possible: %s\n",
get_mncc_name(setup->msg_type), codec_filter_to_str(&trans->cc.codecs));
/* incompatible codecs */
rc = mncc_release_ind(trans->net, trans, trans->callref,
GSM48_CAUSE_LOC_PRN_S_LU,
GSM48_CC_CAUSE_INCOMPAT_DEST /* TODO: correct cause code? */);
trans_free(trans);
msgb_free(msg);
return rc;
}
gsm48_encode_bearer_cap(msg, 0, &bearer_cap);
/* facility */
if (setup->fields & MNCC_F_FACILITY)
gsm48_encode_facility(msg, 0, &setup->facility);

4
tests/msc_vlr/msc_vlr_test_call.c
View File

@ -316,7 +316,7 @@ static void test_call_mt()
VERBOSE_ASSERT(security_mode_ctrl_sent, == true, "%d");
btw("MS sends SecurityModeControl acceptance, VLR accepts, sends CC Setup");
dtap_expect_tx("0305" /* CC: Setup */);
dtap_expect_tx("0305" /* CC: Setup */ "04 07 60 04 05 0b 06 08 87" /* Bearer Cap */);
ms_sends_security_mode_complete(1);
btw("MS confirms call, we create a RAN-side RTP and forward MNCC_CALL_CONF_IND");
@ -419,7 +419,7 @@ static void test_call_mt2()
VERBOSE_ASSERT(security_mode_ctrl_sent, == true, "%d");
btw("MS sends SecurityModeControl acceptance, VLR accepts, sends CC Setup");
dtap_expect_tx("0305" /* CC: Setup */);
dtap_expect_tx("0305" /* CC: Setup */ "04 07 60 04 05 0b 06 08 87" /* Bearer Cap */);
ms_sends_security_mode_complete(1);
btw("MS confirms call, we create a RAN-side RTP and forward MNCC_CALL_CONF_IND");

10
tests/msc_vlr/msc_vlr_test_call.err
View File

@ -761,10 +761,13 @@ DREF msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RES
DMSC msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_AUTHENTICATED}: Received Event MSC_A_EV_TRANSACTION_ACCEPTED
DMSC msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_AUTHENTICATED}: state_chg to MSC_A_ST_COMMUNICATING
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) starting timer T303 with 30 seconds
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) codecs: :0{(no-codecs)} (from: RAN={AMR:octet-align=1#112,AMR-WB:octet-align=1#113})
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) Got no information of remote audio codecs: neither SDP nor Bearer Capability. Trying anyway.
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) codecs: :0{AMR:octet-align=1#112,AMR-WB:octet-align=1#113} (from: RAN={AMR:octet-align=1#112,AMR-WB:octet-align=1#113})
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) new state NULL -> CALL_PRESENT
DIUCS msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_COMMUNICATING}: Sending DTAP: CC GSM48_MT_CC_SETUP
DMSC msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_COMMUNICATING}: RAN encode: DTAP on UTRAN-Iu
- DTAP --UTRAN-Iu--> MS: GSM48_MT_CC_SETUP: 0305
- DTAP --UTRAN-Iu--> MS: GSM48_MT_CC_SETUP: 030504076004050b060887
- DTAP matches expected message
DMSC dummy_msc_i(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){0}: Received Event MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST
DREF VLR subscr IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100 - Paging: now used by 3 (attached,CC,active-conn)
@ -1231,10 +1234,13 @@ DREF msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RES
DMSC msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_AUTHENTICATED}: Received Event MSC_A_EV_TRANSACTION_ACCEPTED
DMSC msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_AUTHENTICATED}: state_chg to MSC_A_ST_COMMUNICATING
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) starting timer T303 with 30 seconds
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) codecs: :0{(no-codecs)} (from: RAN={AMR:octet-align=1#112,AMR-WB:octet-align=1#113})
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) Got no information of remote audio codecs: neither SDP nor Bearer Capability. Trying anyway.
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) codecs: :0{AMR:octet-align=1#112,AMR-WB:octet-align=1#113} (from: RAN={AMR:octet-align=1#112,AMR-WB:octet-align=1#113})
DCC trans(CC:NULL IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP callref-0x423 tid-0) new state NULL -> CALL_PRESENT
DIUCS msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_COMMUNICATING}: Sending DTAP: CC GSM48_MT_CC_SETUP
DMSC msc_a(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){MSC_A_ST_COMMUNICATING}: RAN encode: DTAP on UTRAN-Iu
- DTAP --UTRAN-Iu--> MS: GSM48_MT_CC_SETUP: 0305
- DTAP --UTRAN-Iu--> MS: GSM48_MT_CC_SETUP: 030504076004050b060887
- DTAP matches expected message
DMSC dummy_msc_i(IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100:UTRAN-Iu:PAGING_RESP){0}: Received Event MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST
DREF VLR subscr IMSI-901700000010650:MSISDN-42342:TMSI-0x03020100 - Paging: now used by 3 (attached,CC,active-conn)