src/hlr_sms.c - osmo-hlr - Gitiles

 /* OsmoHLR SMS routing implementation */

 /* (C) 2019 by Vadim Yanitskiy <axilirator@gmail.com>
  *
  * All Rights Reserved
  *
  * 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 <stdint.h>
 #include <string.h>
 #include <errno.h>

 #include <osmocom/core/talloc.h>
 #include <osmocom/core/utils.h>

 #include <osmocom/gsm/protocol/gsm_04_11.h>
 #include <osmocom/gsm/gsm48_ie.h>
 #include <osmocom/gsm/gsup.h>

 #include <osmocom/hlr/hlr.h>
 #include <osmocom/hlr/hlr_sms.h>
 #include <osmocom/hlr/hlr_ussd.h>
 #include <osmocom/hlr/gsup_server.h>
 #include <osmocom/hlr/gsup_router.h>
 #include <osmocom/hlr/logging.h>
 #include <osmocom/hlr/db.h>

 struct hlr_sms_route *sms_route_find(struct hlr *hlr,
 				     enum hlr_sms_route_type type,
 				     const char *pattern)
 {
 	struct hlr_sms_route *rt;

 	llist_for_each_entry(rt, &hlr->sms_routes, list) {
 		if (rt->type != type)
 			continue;
 		if (!strcmp(rt->match_pattern, pattern))
 			return rt;
 	}

 	return NULL;
 }

 struct hlr_sms_route *sms_route_alloc(struct hlr *hlr,
 				      enum hlr_sms_route_type type,
 				      const char *pattern,
 				      const struct hlr_euse *euse)
 {
 	struct hlr_sms_route *rt;

 	if (sms_route_find(hlr, type, pattern))
 		return NULL;

 	rt = talloc(hlr, struct hlr_sms_route);
 	OSMO_ASSERT(rt != NULL);

 	rt->match_pattern = talloc_strdup(rt, pattern);
 	rt->type = type;
 	rt->euse = euse;

 	llist_add_tail(&rt->list, &hlr->sms_routes);

 	return rt;
 }

 void sms_route_del(struct hlr_sms_route *rt)
 {
 	llist_del(&rt->list);
 	talloc_free(rt);
 }

 /* Common helper for preparing to be encoded GSUP message */
 static void gsup_prepare_sm_error(struct osmo_gsup_message *msg,
 				  const struct osmo_gsup_message *src_msg)
 {
 	/* Init a mew GSUP message */
 	*msg = (struct osmo_gsup_message) {
 		.message_type = OSMO_GSUP_TO_MSGT_ERROR(src_msg->message_type),
 		.message_class = OSMO_GSUP_MESSAGE_CLASS_SMS,
 		.sm_rp_mr = src_msg->sm_rp_mr,

 		/* Swap optional source and destination addresses */
 		.destination_name_len = src_msg->source_name_len,
 		.destination_name = src_msg->source_name,
 	};

 	/* Fill in subscriber's IMSI */
 	OSMO_STRLCPY_ARRAY(msg->imsi, src_msg->imsi);
 }

 static int gsup_conn_enc_send(struct osmo_gsup_conn *conn,
 			      struct osmo_gsup_message *msg)
 {
 	struct msgb *gsup_msgb;
 	int rc;

 	gsup_msgb = msgb_alloc_headroom(512, 64, __func__);
 	if (!gsup_msgb) {
 		LOGP(DLSMS, LOGL_ERROR, "Failed to allocate a GSUP message\n");
 		return -ENOMEM;
 	}

 	rc = osmo_gsup_encode(gsup_msgb, msg);
 	if (rc) {
 		LOGP(DLSMS, LOGL_ERROR, "Failed to encode GSUP message '%s' (rc=%d)\n",
 		     osmo_gsup_message_type_name(msg->message_type), rc);
 		return rc;
 	}

 	rc = osmo_gsup_conn_send(conn, gsup_msgb);
 	if (rc) {
 		LOGP(DLSMS, LOGL_ERROR, "Failed to send GSUP message '%s' (rc=%d)\n",
 		     osmo_gsup_message_type_name(msg->message_type), rc);
 		return rc;
 	}

 	return 0;
 }

 /* Short Message delivery status, to be forwarded 'as-is' */
 int forward_sm_res_or_err(struct osmo_gsup_conn *conn,
 			  const struct osmo_gsup_message *gsup,
 			  struct msgb *msg)
 {
 	struct hlr_subscriber subscr;
 	char src_name_buf[32];
 	char dst_name_buf[32];
 	int rc;

 	rc = db_subscr_get_by_imsi(g_hlr->dbc, gsup->imsi, &subscr);
 	if (rc) {
 		LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' for unknown subscriber IMSI-%s\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
 		/* TODO: send some error back? */
 		msgb_free(msg);
 		return -ENODEV;
 	}

 	/* Make sure destination name is present */
 	if (gsup->destination_name == NULL || !gsup->destination_name_len) {
 		LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) without destination name\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
 		/* TODO: send some error back? */
 		msgb_free(msg);
 		return -EINVAL;
 	}

 	/* Make sure source name is present */
 	if (gsup->source_name == NULL || !gsup->source_name_len) {
 		LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) without source name\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
 		/* TODO: send some error back? */
 		msgb_free(msg);
 		return -EINVAL;
 	}

 	LOGP(DLSMS, LOGL_INFO, "Forward '%s' (IMSI-%s) from %s to %s\n",
 	     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
 	     osmo_quote_str_buf2(src_name_buf, sizeof(src_name_buf),
 				 (const char *) gsup->source_name,
 				 gsup->source_name_len),
 	     osmo_quote_str_buf2(dst_name_buf, sizeof(dst_name_buf),
 				 (const char *) gsup->destination_name,
 				 gsup->destination_name_len));

 	rc = osmo_gsup_addr_send(conn->server, gsup->destination_name,
 				 gsup->destination_name_len, msg);
 	if (rc) {
 		LOGP(DLSMS, LOGL_NOTICE, "Failed to forward '%s' (IMSI-%s)\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
 		/* osmo_gsup_addr_send() free()d msg */
 		return rc;
 	}

 	return 0;
 }

 static const struct hlr_euse *find_euse(const struct hlr_subscriber *subscr,
 					const char *smsc_addr)
 {
 	struct hlr_sms_route *rt;
 	const char *pattern;

 	/* Iterate over all known routes */
 	llist_for_each_entry(rt, &g_hlr->sms_routes, list) {
 		switch (rt->type) {
 		case HLR_SMS_RT_SMSC_ADDR:
 			pattern = smsc_addr;
 			break;
 		case HLR_SMS_RT_SENDER_MSISDN:
 			pattern = subscr->msisdn;
 			break;
 		case HLR_SMS_RT_SENDER_IMSI:
 			pattern = subscr->imsi;
 			break;
 		default:
 			/* Shall not happen, make Coverity happy */
 			continue;
 		}

 		if (strcmp(rt->match_pattern, pattern) == 0)
 			return rt->euse;
 	}

 	/* Fall-back to default route if nothing will be found */
 	return g_hlr->sms_euse_default;
 }

 static const struct osmo_gsup_conn *find_conn(struct osmo_gsup_server *srv,
 					      const struct hlr_euse *euse)
 {
 	char euse_addr[128];
 	int rc;

 	rc = snprintf(euse_addr, sizeof(euse_addr), "EUSE-%s", euse->name);
 	return gsup_route_find(srv, (uint8_t *) euse_addr, rc + 1);
 }

 /* Short Message from MSC/VLR towards SMSC */
 int forward_mo_sms(struct osmo_gsup_conn *conn,
 		   const struct osmo_gsup_message *gsup,
 		   struct msgb *msg)
 {
 	char smsc_addr[GSM23003_MSISDN_MAX_DIGITS + 1];
 	struct osmo_gsup_message rsp_msg;
 	struct hlr_subscriber subscr;
 	uint8_t ext, ton, npi;
 	uint8_t sm_rp_cause;
 	int rc;

 	rc = db_subscr_get_by_imsi(g_hlr->dbc, gsup->imsi, &subscr);
 	if (rc) {
 		LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' for unknown subscriber IMSI-%s\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		rsp_msg.cause = GMM_CAUSE_IMSI_UNKNOWN;
 		goto exit_error;
 	}

 	/* Make sure SM-RP-DA (SMSC address) is present */
 	if (gsup->sm_rp_da == NULL || !gsup->sm_rp_da_len) {
 		LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) without mandatory SM-RP-DA\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		rsp_msg.cause = GMM_CAUSE_INV_MAND_INFO;
 		goto exit_error;
 	}

 	if (gsup->sm_rp_da_type != OSMO_GSUP_SMS_SM_RP_ODA_SMSC_ADDR) {
 		LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) with unexpected SM-RP-DA 0x%02x\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
 		     gsup->sm_rp_da_type);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		rsp_msg.cause = GMM_CAUSE_INV_MAND_INFO;
 		goto exit_error;
 	}

 	/* Parse ToN (Type of Number) / NPI (Numbering Plan Indicator) */
 	ext = (gsup->sm_rp_da[0] >> 7) ^ 0x01; /* NOTE: inversed */
 	ton = (gsup->sm_rp_da[0] >> 4) & 0x07;
 	npi = gsup->sm_rp_da[0] & 0x0f;

 	/* We only support International ISDN/telephone format */
 	if (ext || ton != 0x01 || npi != 0x01) {
 		LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) with unsupported SMSC address format: "
 					 "ToN=0x%02x, NPI=0x%02x\n, extension=%s\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
 		     ton, npi, ext ? "yes" : "no");
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		rsp_msg.cause = GMM_CAUSE_SEM_INCORR_MSG;
 		goto exit_error;
 	}

 	/* Decode SMSC address from SM-RP-DA */
 	rc = osmo_bcd2str(smsc_addr, sizeof(smsc_addr), gsup->sm_rp_da + 1,
 			  2, (gsup->sm_rp_da_len - 1) * 2, true);
 	if (rc < 0 || rc >= sizeof(smsc_addr)) {
 		LOGP(DLSMS, LOGL_NOTICE, "Failed to decode SMSC address from '%s' (IMSI-%s): rc=%d\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi, rc);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		rsp_msg.cause = GMM_CAUSE_SEM_INCORR_MSG;
 		goto exit_error;
 	}

 	/* Attempt to find a EUSE */
 	const struct hlr_euse *euse = find_euse(&subscr, smsc_addr);
 	if (euse == NULL) {
 		LOGP(DLSMS, LOGL_NOTICE, "Failed to find a route for '%s' (IMSI-%s, MR-0x%02x)\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi, *gsup->sm_rp_mr);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		sm_rp_cause = GSM411_RP_CAUSE_MO_NUM_UNASSIGNED;
 		rsp_msg.sm_rp_cause = &sm_rp_cause;
 		goto exit_error;
 	}

 	const struct osmo_gsup_conn *euse_conn = find_conn(conn->server, euse);
 	if (euse_conn == NULL) {
 		LOGP(DLSMS, LOGL_ERROR, "EUSE '%s' is not connected!\n", euse->name);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		sm_rp_cause = GSM411_RP_CAUSE_MO_TEMP_FAIL;
 		rsp_msg.sm_rp_cause = &sm_rp_cause;
 		goto exit_error;
 	}

 	LOGP(DLSMS, LOGL_INFO, "Forwarding '%s' (IMSI-%s, MR-0x%02x) to SMSC '%s'\n",
 	     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
 	     *gsup->sm_rp_mr, euse->name);

 	/* HACK: make sure source name is present, fill in if needed */
 	if (gsup->source_name == NULL || !gsup->source_name_len) {
 		/* FIXME: distinguish between MSC/VLR and SGSN */
 		msgb_tlv_put(msg, OSMO_GSUP_SOURCE_NAME_IE,
 			     strlen(subscr.vlr_number) + 1,
 			     (uint8_t *) subscr.vlr_number);
 	}

 	/* Ensure the buffer has enough headroom to put IPA headers */
 	msgb_pull_to_l2(msg);

 	/* Finally forward the original message */
 	rc = osmo_gsup_conn_send((struct osmo_gsup_conn *) euse_conn, msg);
 	if (rc) {
 		LOGP(DLSMS, LOGL_ERROR, "Failed to send GSUP message '%s' (rc=%d)\n",
 		     osmo_gsup_message_type_name(gsup->message_type), rc);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		sm_rp_cause = GSM411_RP_CAUSE_MO_TEMP_FAIL;
 		rsp_msg.sm_rp_cause = &sm_rp_cause;
 		msg = NULL; /* free()d by osmo_gsup_conn_send() */
 		goto exit_error;
 	}

 	return 0;

 exit_error:
 	gsup_conn_enc_send(conn, &rsp_msg);
 	if (msg != NULL)
 		talloc_free(msg);
 	return rc;
 }

 /* Short Message from SMSC towards MSC/VLR */
 int forward_mt_sms(struct osmo_gsup_conn *conn,
 		   const struct osmo_gsup_message *gsup,
 		   struct msgb *msg)
 {
 	struct osmo_gsup_message rsp_msg;
 	struct hlr_subscriber subscr;
 	uint8_t sm_rp_cause;
 	int rc;

 	rc = db_subscr_get_by_imsi(g_hlr->dbc, gsup->imsi, &subscr);
 	if (rc) {
 		LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' for unknown subscriber IMSI-%s\n",
 		     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		rsp_msg.cause = GMM_CAUSE_IMSI_UNKNOWN;
 		goto exit_error;
 	}

 #if 0
 	LOGP(DLSMS, LOGL_INFO, "Forwarding '%s' (IMSI-%s, MR-0x%02x) to MSC/VLR '%s'\n",
 	     osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
 	     *gsup->sm_rp_mr, FIXME!);

 	/* Finally forward the original message */
 	rc = osmo_gsup_conn_send(subscr_conn, msg);
 	if (rc) {
 		LOGP(DLSMS, LOGL_ERROR, "Failed to send GSUP message '%s' (rc=%d)\n",
 		     osmo_gsup_message_type_name(gsup->message_type), rc);
 		gsup_prepare_sm_error(&rsp_msg, gsup);
 		sm_rp_cause = GSM411_RP_CAUSE_MO_TEMP_FAIL;
 		rsp_msg.sm_rp_cause = &sm_rp_cause;
 		msg = NULL; /* free()d by osmo_gsup_conn_send() */
 		goto exit_error;
 	}
 #endif

 	return 0;

 exit_error:
 	gsup_conn_enc_send(conn, &rsp_msg);
 	if (msg != NULL)
 		talloc_free(msg);
 	return rc;
 }
	/* OsmoHLR SMS routing implementation */

	/* (C) 2019 by Vadim Yanitskiy <axilirator@gmail.com>
	*
	* All Rights Reserved
	*
	* 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 <stdint.h>
	#include <string.h>
	#include <errno.h>

	#include <osmocom/core/talloc.h>
	#include <osmocom/core/utils.h>

	#include <osmocom/gsm/protocol/gsm_04_11.h>
	#include <osmocom/gsm/gsm48_ie.h>
	#include <osmocom/gsm/gsup.h>

	#include <osmocom/hlr/hlr.h>
	#include <osmocom/hlr/hlr_sms.h>
	#include <osmocom/hlr/hlr_ussd.h>
	#include <osmocom/hlr/gsup_server.h>
	#include <osmocom/hlr/gsup_router.h>
	#include <osmocom/hlr/logging.h>
	#include <osmocom/hlr/db.h>

	struct hlr_sms_route sms_route_find(struct hlr hlr,
	enum hlr_sms_route_type type,
	const char *pattern)
	{
	struct hlr_sms_route *rt;

	llist_for_each_entry(rt, &hlr->sms_routes, list) {
	if (rt->type != type)
	continue;
	if (!strcmp(rt->match_pattern, pattern))
	return rt;
	}

	return NULL;
	}

	struct hlr_sms_route sms_route_alloc(struct hlr hlr,
	enum hlr_sms_route_type type,
	const char *pattern,
	const struct hlr_euse *euse)
	{
	struct hlr_sms_route *rt;

	if (sms_route_find(hlr, type, pattern))
	return NULL;

	rt = talloc(hlr, struct hlr_sms_route);
	OSMO_ASSERT(rt != NULL);

	rt->match_pattern = talloc_strdup(rt, pattern);
	rt->type = type;
	rt->euse = euse;

	llist_add_tail(&rt->list, &hlr->sms_routes);

	return rt;
	}

	void sms_route_del(struct hlr_sms_route *rt)
	{
	llist_del(&rt->list);
	talloc_free(rt);
	}

	/* Common helper for preparing to be encoded GSUP message */
	static void gsup_prepare_sm_error(struct osmo_gsup_message *msg,
	const struct osmo_gsup_message *src_msg)
	{
	/* Init a mew GSUP message */
	*msg = (struct osmo_gsup_message) {
	.message_type = OSMO_GSUP_TO_MSGT_ERROR(src_msg->message_type),
	.message_class = OSMO_GSUP_MESSAGE_CLASS_SMS,
	.sm_rp_mr = src_msg->sm_rp_mr,

	/* Swap optional source and destination addresses */
	.destination_name_len = src_msg->source_name_len,
	.destination_name = src_msg->source_name,
	};

	/* Fill in subscriber's IMSI */
	OSMO_STRLCPY_ARRAY(msg->imsi, src_msg->imsi);
	}

	static int gsup_conn_enc_send(struct osmo_gsup_conn *conn,
	struct osmo_gsup_message *msg)
	{
	struct msgb *gsup_msgb;
	int rc;

	gsup_msgb = msgb_alloc_headroom(512, 64, __func__);
	if (!gsup_msgb) {
	LOGP(DLSMS, LOGL_ERROR, "Failed to allocate a GSUP message\n");
	return -ENOMEM;
	}

	rc = osmo_gsup_encode(gsup_msgb, msg);
	if (rc) {
	LOGP(DLSMS, LOGL_ERROR, "Failed to encode GSUP message '%s' (rc=%d)\n",
	osmo_gsup_message_type_name(msg->message_type), rc);
	return rc;
	}

	rc = osmo_gsup_conn_send(conn, gsup_msgb);
	if (rc) {
	LOGP(DLSMS, LOGL_ERROR, "Failed to send GSUP message '%s' (rc=%d)\n",
	osmo_gsup_message_type_name(msg->message_type), rc);
	return rc;
	}

	return 0;
	}

	/* Short Message delivery status, to be forwarded 'as-is' */
	int forward_sm_res_or_err(struct osmo_gsup_conn *conn,
	const struct osmo_gsup_message *gsup,
	struct msgb *msg)
	{
	struct hlr_subscriber subscr;
	char src_name_buf[32];
	char dst_name_buf[32];
	int rc;

	rc = db_subscr_get_by_imsi(g_hlr->dbc, gsup->imsi, &subscr);
	if (rc) {
	LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' for unknown subscriber IMSI-%s\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
	/* TODO: send some error back? */
	msgb_free(msg);
	return -ENODEV;
	}

	/* Make sure destination name is present */
	if (gsup->destination_name == NULL \|\| !gsup->destination_name_len) {
	LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) without destination name\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
	/* TODO: send some error back? */
	msgb_free(msg);
	return -EINVAL;
	}

	/* Make sure source name is present */
	if (gsup->source_name == NULL \|\| !gsup->source_name_len) {
	LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) without source name\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
	/* TODO: send some error back? */
	msgb_free(msg);
	return -EINVAL;
	}

	LOGP(DLSMS, LOGL_INFO, "Forward '%s' (IMSI-%s) from %s to %s\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
	osmo_quote_str_buf2(src_name_buf, sizeof(src_name_buf),
	(const char *) gsup->source_name,
	gsup->source_name_len),
	osmo_quote_str_buf2(dst_name_buf, sizeof(dst_name_buf),
	(const char *) gsup->destination_name,
	gsup->destination_name_len));

	rc = osmo_gsup_addr_send(conn->server, gsup->destination_name,
	gsup->destination_name_len, msg);
	if (rc) {
	LOGP(DLSMS, LOGL_NOTICE, "Failed to forward '%s' (IMSI-%s)\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
	/* osmo_gsup_addr_send() free()d msg */
	return rc;
	}

	return 0;
	}

	static const struct hlr_euse find_euse(const struct hlr_subscriber subscr,
	const char *smsc_addr)
	{
	struct hlr_sms_route *rt;
	const char *pattern;

	/* Iterate over all known routes */
	llist_for_each_entry(rt, &g_hlr->sms_routes, list) {
	switch (rt->type) {
	case HLR_SMS_RT_SMSC_ADDR:
	pattern = smsc_addr;
	break;
	case HLR_SMS_RT_SENDER_MSISDN:
	pattern = subscr->msisdn;
	break;
	case HLR_SMS_RT_SENDER_IMSI:
	pattern = subscr->imsi;
	break;
	default:
	/* Shall not happen, make Coverity happy */
	continue;
	}

	if (strcmp(rt->match_pattern, pattern) == 0)
	return rt->euse;
	}

	/* Fall-back to default route if nothing will be found */
	return g_hlr->sms_euse_default;
	}

	static const struct osmo_gsup_conn find_conn(struct osmo_gsup_server srv,
	const struct hlr_euse *euse)
	{
	char euse_addr[128];
	int rc;

	rc = snprintf(euse_addr, sizeof(euse_addr), "EUSE-%s", euse->name);
	return gsup_route_find(srv, (uint8_t *) euse_addr, rc + 1);
	}

	/* Short Message from MSC/VLR towards SMSC */
	int forward_mo_sms(struct osmo_gsup_conn *conn,
	const struct osmo_gsup_message *gsup,
	struct msgb *msg)
	{
	char smsc_addr[GSM23003_MSISDN_MAX_DIGITS + 1];
	struct osmo_gsup_message rsp_msg;
	struct hlr_subscriber subscr;
	uint8_t ext, ton, npi;
	uint8_t sm_rp_cause;
	int rc;

	rc = db_subscr_get_by_imsi(g_hlr->dbc, gsup->imsi, &subscr);
	if (rc) {
	LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' for unknown subscriber IMSI-%s\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	rsp_msg.cause = GMM_CAUSE_IMSI_UNKNOWN;
	goto exit_error;
	}

	/* Make sure SM-RP-DA (SMSC address) is present */
	if (gsup->sm_rp_da == NULL \|\| !gsup->sm_rp_da_len) {
	LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) without mandatory SM-RP-DA\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	rsp_msg.cause = GMM_CAUSE_INV_MAND_INFO;
	goto exit_error;
	}

	if (gsup->sm_rp_da_type != OSMO_GSUP_SMS_SM_RP_ODA_SMSC_ADDR) {
	LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) with unexpected SM-RP-DA 0x%02x\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
	gsup->sm_rp_da_type);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	rsp_msg.cause = GMM_CAUSE_INV_MAND_INFO;
	goto exit_error;
	}

	/* Parse ToN (Type of Number) / NPI (Numbering Plan Indicator) */
	ext = (gsup->sm_rp_da[0] >> 7) ^ 0x01; /* NOTE: inversed */
	ton = (gsup->sm_rp_da[0] >> 4) & 0x07;
	npi = gsup->sm_rp_da[0] & 0x0f;

	/* We only support International ISDN/telephone format */
	if (ext \|\| ton != 0x01 \|\| npi != 0x01) {
	LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' (IMSI-%s) with unsupported SMSC address format: "
	"ToN=0x%02x, NPI=0x%02x\n, extension=%s\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
	ton, npi, ext ? "yes" : "no");
	gsup_prepare_sm_error(&rsp_msg, gsup);
	rsp_msg.cause = GMM_CAUSE_SEM_INCORR_MSG;
	goto exit_error;
	}

	/* Decode SMSC address from SM-RP-DA */
	rc = osmo_bcd2str(smsc_addr, sizeof(smsc_addr), gsup->sm_rp_da + 1,
	2, (gsup->sm_rp_da_len - 1) * 2, true);
	if (rc < 0 \|\| rc >= sizeof(smsc_addr)) {
	LOGP(DLSMS, LOGL_NOTICE, "Failed to decode SMSC address from '%s' (IMSI-%s): rc=%d\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi, rc);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	rsp_msg.cause = GMM_CAUSE_SEM_INCORR_MSG;
	goto exit_error;
	}

	/* Attempt to find a EUSE */
	const struct hlr_euse *euse = find_euse(&subscr, smsc_addr);
	if (euse == NULL) {
	LOGP(DLSMS, LOGL_NOTICE, "Failed to find a route for '%s' (IMSI-%s, MR-0x%02x)\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi, *gsup->sm_rp_mr);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	sm_rp_cause = GSM411_RP_CAUSE_MO_NUM_UNASSIGNED;
	rsp_msg.sm_rp_cause = &sm_rp_cause;
	goto exit_error;
	}

	const struct osmo_gsup_conn *euse_conn = find_conn(conn->server, euse);
	if (euse_conn == NULL) {
	LOGP(DLSMS, LOGL_ERROR, "EUSE '%s' is not connected!\n", euse->name);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	sm_rp_cause = GSM411_RP_CAUSE_MO_TEMP_FAIL;
	rsp_msg.sm_rp_cause = &sm_rp_cause;
	goto exit_error;
	}

	LOGP(DLSMS, LOGL_INFO, "Forwarding '%s' (IMSI-%s, MR-0x%02x) to SMSC '%s'\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
	*gsup->sm_rp_mr, euse->name);

	/* HACK: make sure source name is present, fill in if needed */
	if (gsup->source_name == NULL \|\| !gsup->source_name_len) {
	/* FIXME: distinguish between MSC/VLR and SGSN */
	msgb_tlv_put(msg, OSMO_GSUP_SOURCE_NAME_IE,
	strlen(subscr.vlr_number) + 1,
	(uint8_t *) subscr.vlr_number);
	}

	/* Ensure the buffer has enough headroom to put IPA headers */
	msgb_pull_to_l2(msg);

	/* Finally forward the original message */
	rc = osmo_gsup_conn_send((struct osmo_gsup_conn *) euse_conn, msg);
	if (rc) {
	LOGP(DLSMS, LOGL_ERROR, "Failed to send GSUP message '%s' (rc=%d)\n",
	osmo_gsup_message_type_name(gsup->message_type), rc);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	sm_rp_cause = GSM411_RP_CAUSE_MO_TEMP_FAIL;
	rsp_msg.sm_rp_cause = &sm_rp_cause;
	msg = NULL; /* free()d by osmo_gsup_conn_send() */
	goto exit_error;
	}

	return 0;

	exit_error:
	gsup_conn_enc_send(conn, &rsp_msg);
	if (msg != NULL)
	talloc_free(msg);
	return rc;
	}

	/* Short Message from SMSC towards MSC/VLR */
	int forward_mt_sms(struct osmo_gsup_conn *conn,
	const struct osmo_gsup_message *gsup,
	struct msgb *msg)
	{
	struct osmo_gsup_message rsp_msg;
	struct hlr_subscriber subscr;
	uint8_t sm_rp_cause;
	int rc;

	rc = db_subscr_get_by_imsi(g_hlr->dbc, gsup->imsi, &subscr);
	if (rc) {
	LOGP(DLSMS, LOGL_NOTICE, "Rx '%s' for unknown subscriber IMSI-%s\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	rsp_msg.cause = GMM_CAUSE_IMSI_UNKNOWN;
	goto exit_error;
	}

	#if 0
	LOGP(DLSMS, LOGL_INFO, "Forwarding '%s' (IMSI-%s, MR-0x%02x) to MSC/VLR '%s'\n",
	osmo_gsup_message_type_name(gsup->message_type), gsup->imsi,
	*gsup->sm_rp_mr, FIXME!);

	/* Finally forward the original message */
	rc = osmo_gsup_conn_send(subscr_conn, msg);
	if (rc) {
	LOGP(DLSMS, LOGL_ERROR, "Failed to send GSUP message '%s' (rc=%d)\n",
	osmo_gsup_message_type_name(gsup->message_type), rc);
	gsup_prepare_sm_error(&rsp_msg, gsup);
	sm_rp_cause = GSM411_RP_CAUSE_MO_TEMP_FAIL;
	rsp_msg.sm_rp_cause = &sm_rp_cause;
	msg = NULL; /* free()d by osmo_gsup_conn_send() */
	goto exit_error;
	}
	#endif

	return 0;

	exit_error:
	gsup_conn_enc_send(conn, &rsp_msg);
	if (msg != NULL)
	talloc_free(msg);
	return rc;
	}