Change in osmo-bsc[master]: codec_pref: handle S0-S15 in ASSIGNMENT REQUEST

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dexter gerrit-no-reply at lists.osmocom.org
Fri Sep 21 14:47:41 UTC 2018


dexter has uploaded this change for review. ( https://gerrit.osmocom.org/11060


Change subject: codec_pref: handle S0-S15 in ASSIGNMENT REQUEST
......................................................................

codec_pref: handle S0-S15 in ASSIGNMENT REQUEST

Opposed to all other codecs that are common in GSM, AMR requires a codec
configuration that is expressed by a bitmask (S0 to S15) in the speech
codec list in the ASSIGNMENT REQUEST. Also the BSC acknowledges those
configuration in the ASSIGNMENT COMPLETE message.

At the moment osmo-bsc ignores all incoming configuration bits. The bits
in the ASSIGNMENT COMPLETE speech codec (choosen) field are hardcoded.

- Store the configuration bits while parsing the ASSIGNMENT COMPLETE
- Create an intersection with the configuration that is actually
  supported by the BSS
- Return the resulting (choosen) configuration bits with the assignment
  complete message.

Change-Id: I2d8ded51b3eb4c003fe2da6f2d6f48d001b73737
Related: OS#3529
---
M include/osmocom/bsc/codec_pref.h
M include/osmocom/bsc/gsm_data.h
M src/osmo-bsc/assignment_fsm.c
M src/osmo-bsc/codec_pref.c
M src/osmo-bsc/handover_fsm.c
M src/osmo-bsc/osmo_bsc_bssap.c
M tests/codec_pref/codec_pref_test.c
7 files changed, 89 insertions(+), 50 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/60/11060/1

diff --git a/include/osmocom/bsc/codec_pref.h b/include/osmocom/bsc/codec_pref.h
index 09aaa60..3085ad4 100644
--- a/include/osmocom/bsc/codec_pref.h
+++ b/include/osmocom/bsc/codec_pref.h
@@ -12,11 +12,11 @@
 
 int match_codec_pref(enum gsm48_chan_mode *chan_mode,
 		     bool *full_rate,
+		     uint16_t *s15_s0,
 		     const struct gsm0808_channel_type *ct,
 		     const struct gsm0808_speech_codec_list *scl,
-		     struct gsm_audio_support * const *audio_support,
-		     int audio_length,
-		     const struct bts_codec_conf *bts_codec);
+		     const struct bsc_msc_data *msc,
+		     const struct gsm_bts *bts);
 
 void gen_bss_supported_codec_list(struct gsm0808_speech_codec_list *scl,
 				  const struct bsc_msc_data *msc,
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 33a5a8d..7c91e59 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -109,6 +109,7 @@
 
 	enum gsm48_chan_mode chan_mode;
 	bool full_rate;
+	uint16_t s15_s0;
 };
 
 struct assignment_fsm_data {
diff --git a/src/osmo-bsc/assignment_fsm.c b/src/osmo-bsc/assignment_fsm.c
index 5304d6c..221657e 100644
--- a/src/osmo-bsc/assignment_fsm.c
+++ b/src/osmo-bsc/assignment_fsm.c
@@ -169,8 +169,8 @@
 		 * assignment complete message. */
 		if (gscon_is_aoip(conn)) {
 			/* Extrapolate speech codec from speech mode */
-			/* FIXME: AMR codec configuration must be derived from lchan1! */
 			gsm0808_speech_codec_from_chan_type(&sc, perm_spch);
+			sc.cfg = conn->assignment.req.s15_s0;
 			sc_ptr = ≻
 		}
 	}
diff --git a/src/osmo-bsc/codec_pref.c b/src/osmo-bsc/codec_pref.c
index c998e60..7aa5130 100644
--- a/src/osmo-bsc/codec_pref.c
+++ b/src/osmo-bsc/codec_pref.c
@@ -94,14 +94,18 @@
  * 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_channel_type *ct,
-			    const struct gsm0808_speech_codec_list *scl, uint8_t perm_spch)
+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++) {
@@ -129,8 +133,10 @@
 	/* 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)
+		if (sc.type == scl->codec[i].type) {
+			*sc_match = &scl->codec[i];
 			return true;
+		}
 	}
 
 	return false;
@@ -168,40 +174,74 @@
 	return false;
 }
 
+/* Helper function to 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. Thsi 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;
+}
+
 /*! Match the codec preferences from local config with a received codec preferences IEs received from the
  * MSC and the BTS' codec configuration.
  *  \param[out] chan_mode GSM 04.08 channel mode.
  *  \param[out] full_rate true if full-rate.
+ *  \param[out] s15_s0 codec configuration bits S15-S0 (AMR)
  *  \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] audio_support List of allowed codecs as from local config.
- *  \param[in] audio_length Number of items in audio_support.
- *  \param[in] bts_codec BTS codec configuration.
+ *  \param[in] msc associated msc (current codec settings).
+ *  \param[in] bts associated bts (current codec settings).
  *  \returns 0 on success, -1 in case no match was found */
 int match_codec_pref(enum gsm48_chan_mode *chan_mode,
 		     bool *full_rate,
+		     uint16_t *s15_s0,
 		     const struct gsm0808_channel_type *ct,
 		     const struct gsm0808_speech_codec_list *scl,
-		     struct gsm_audio_support * const *audio_support,
-		     int audio_length,
-		     const struct bts_codec_conf *bts_codec)
+		     const struct bsc_msc_data *msc,
+		     const struct gsm_bts *bts)
 {
 	unsigned int i;
 	uint8_t perm_spch;
 	bool match = false;
+	const struct gsm0808_speech_codec *sc_match = NULL;
+	uint16_t amr_s15_s0_supported;
 
-	for (i = 0; i < audio_length; i++) {
+	/* 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(audio_support[i]);
+		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_codec, perm_spch))
+		if (!test_codec_support_bts(&bts->codec, 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(ct, scl, perm_spch)) {
+		if (test_codec_pref(&sc_match, scl, ct, perm_spch)) {
 			match = true;
 			break;
 		}
@@ -211,6 +251,7 @@
 	if (!match) {
 		*full_rate = false;
 		*chan_mode = GSM48_CMODE_SIGN;
+		*s15_s0 = 0;
 		return -1;
 	}
 
@@ -240,6 +281,24 @@
 	/* Lookup a channel mode for the selected codec */
 	*chan_mode = gsm88_to_chan_mode(perm_spch);
 
+	/* Special handling for AMR */
+	if (perm_spch == GSM0808_PERM_HR3 || perm_spch == GSM0808_PERM_FR3)
+	{
+		/* 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 agein
+		 * lookup what we support and generate an intersection. All
+		 * further processing is then done with this intersection
+		 * result */
+		amr_s15_s0_supported = gen_bss_supported_amr_s15_s0(msc, bts, (perm_spch == GSM0808_PERM_HR3));
+		if (sc_match)
+			*s15_s0 = sc_match->cfg & amr_s15_s0_supported;
+		else
+			*s15_s0 = amr_s15_s0_supported;
+	} else
+		*s15_s0 = 0;
+
 	return 0;
 }
 
@@ -254,11 +313,6 @@
 	uint8_t perm_spch;
 	unsigned int i;
 	int rc;
-	uint16_t amr_s15_s0_bts;
-	uint16_t amr_s15_s0_msc;
-	uint16_t amr_s15_s0;
-	const struct gsm48_multi_rate_conf *amr_cfg_bts;
-	const struct gsm48_multi_rate_conf *amr_cfg_msc;
 
 	memset(scl, 0, sizeof(*scl));
 
@@ -280,28 +334,8 @@
 		/* 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) {
-
-			/* First lookup the BTS specific AMR rate configuration. Thsi config
-			 * is set via the VTY for each BTS individually. In cases where no
-			 * configuration is set we will assume a safe default */
-			if (msc->audio_support[i]->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);
-			}
-
-			/* At next, 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. */
-			amr_s15_s0 = amr_s15_s0_bts & amr_s15_s0_msc;
-			scl->codec[scl->len].cfg = amr_s15_s0;
-		}
+		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++;
 	}
diff --git a/src/osmo-bsc/handover_fsm.c b/src/osmo-bsc/handover_fsm.c
index 9d558bc..e95ab9c 100644
--- a/src/osmo-bsc/handover_fsm.c
+++ b/src/osmo-bsc/handover_fsm.c
@@ -522,6 +522,7 @@
 	int match_idx;
 	enum gsm48_chan_mode mode;
 	bool full_rate;
+	uint16_t s15_s0;
 	struct osmo_fsm_inst *fi;
 
 	handover_fsm_alloc(conn);
@@ -560,8 +561,9 @@
 		       bts->nr, req->cell_id_target_name);
 
 		/* Figure out channel type */
-		if (match_codec_pref(&mode, &full_rate, &req->ct, &req->scl, msc->audio_support,
-				     msc->audio_length, &bts->codec)) {
+		if (match_codec_pref(&mode, &full_rate, &s15_s0, &req->ct, &req->scl, msc, bts)) {
+			/* FIXME: use the value in s15_s0 that has been computed by
+			 * match_codec_pref(). */
 			LOG_HO(conn, LOGL_DEBUG,
 			       "BTS %u has no matching channel codec (%s, speech codec list len = %u)",
 			       bts->nr, gsm0808_channel_type_name(&req->ct), req->scl.len);
diff --git a/src/osmo-bsc/osmo_bsc_bssap.c b/src/osmo-bsc/osmo_bsc_bssap.c
index 97daa5c..537b851 100644
--- a/src/osmo-bsc/osmo_bsc_bssap.c
+++ b/src/osmo-bsc/osmo_bsc_bssap.c
@@ -603,6 +603,7 @@
 	uint16_t cic = 0;
 	enum gsm48_chan_mode chan_mode = GSM48_CMODE_SIGN;
 	bool full_rate = false;
+	uint16_t s15_s0 = 0;
 	bool aoip = false;
 	struct sockaddr_storage rtp_addr;
 	struct gsm0808_channel_type ct;
@@ -706,9 +707,8 @@
 
 		/* Match codec information from the assignment command against the
 		 * local preferences of the BSC and BTS */
-		rc = match_codec_pref(&chan_mode, &full_rate, &ct, &conn->codec_list,
-				      msc->audio_support, msc->audio_length,
-				      &conn_get_bts(conn)->codec);
+		rc = match_codec_pref(&chan_mode, &full_rate, &s15_s0, &ct, &conn->codec_list,
+				      msc, conn_get_bts(conn));
 		if (rc < 0) {
 			LOGP(DMSC, LOGL_ERROR, "No supported audio type found for channel_type ="
 			     " { ch_indctr=0x%x, ch_rate_type=0x%x, perm_spch=[ %s] }\n",
@@ -730,6 +730,7 @@
 			.msc_assigned_cic = cic,
 			.chan_mode = chan_mode,
 			.full_rate = full_rate,
+			.s15_s0 = s15_s0
 		};
 		if (aoip) {
 			unsigned int rc = osmo_sockaddr_to_str_and_uint(req.msc_rtp_addr,
diff --git a/tests/codec_pref/codec_pref_test.c b/tests/codec_pref/codec_pref_test.c
index 20e3525..34b8c75 100644
--- a/tests/codec_pref/codec_pref_test.c
+++ b/tests/codec_pref/codec_pref_test.c
@@ -374,6 +374,7 @@
 	unsigned int i;
 	bool full_rate;
 	enum gsm48_chan_mode chan_mode;
+	uint16_t s15_s0;
 
 	printf("Determining channel mode and rate:\n");
 
@@ -398,7 +399,7 @@
 	printf("   codec->efr=%u\n", bts->codec.efr);
 	printf("   codec->amr=%u\n", bts->codec.amr);
 
-	rc = match_codec_pref(&chan_mode, &full_rate, ct, scl, msc->audio_support, msc->audio_length, &bts->codec);
+	rc = match_codec_pref(&chan_mode, &full_rate, &s15_s0, ct, scl, msc, bts);
 	printf(" * result: rc=%i, full_rate=%i, chan_mode=%s\n", rc, full_rate, gsm48_chan_mode_name(chan_mode));
 
 	printf("\n");

-- 
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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I2d8ded51b3eb4c003fe2da6f2d6f48d001b73737
Gerrit-Change-Number: 11060
Gerrit-PatchSet: 1
Gerrit-Owner: dexter <pmaier at sysmocom.de>
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