move openbsc/* to repos root

This is the first step in creating this repository from the legacy openbsc.git.

Like all other Osmocom repositories, keep the autoconf and automake files in
the repository root. openbsc.git has been the sole exception, which ends now.

Change-Id: I9c6f2a448d9cb1cc088cf1cf6918b69d7e69b4e7

1 files changed, 1736 insertions, 0 deletions

diff --git a/src/osmo-bsc_nat/bsc_nat.c b/src/osmo-bsc_nat/bsc_nat.c
new file mode 100644
index 000000000..daa066d05
--- /dev/null
+++ b/src/osmo-bsc_nat/bsc_nat.c
@@ -0,0 +1,1736 @@
+/* BSC Multiplexer/NAT */
+
+/*
+ * (C) 2010-2013 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010-2013 by On-Waves
+ * (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ * 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 <sys/socket.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <arpa/inet.h>
+
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <libgen.h>
+
+#define _GNU_SOURCE
+#include <getopt.h>
+
+#include <openbsc/debug.h>
+#include <openbsc/bsc_msc.h>
+#include <openbsc/bsc_nat.h>
+#include <openbsc/bsc_nat_sccp.h>
+#include <openbsc/bsc_msg_filter.h>
+#include <openbsc/ipaccess.h>
+#include <openbsc/abis_nm.h>
+#include <openbsc/socket.h>
+#include <openbsc/vty.h>
+
+#include <osmocom/ctrl/control_cmd.h>
+#include <osmocom/ctrl/control_if.h>
+#include <osmocom/ctrl/ports.h>
+#include <osmocom/ctrl/control_vty.h>
+
+#include <osmocom/crypt/auth.h>
+
+#include <osmocom/core/application.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/stats.h>
+
+#include <osmocom/gsm/tlv.h>
+#include <osmocom/gsm/gsm0808.h>
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+
+#include <osmocom/vty/telnet_interface.h>
+#include <osmocom/vty/vty.h>
+#include <osmocom/vty/logging.h>
+#include <osmocom/vty/stats.h>
+#include <osmocom/vty/ports.h>
+
+#include <osmocom/sccp/sccp.h>
+
+#include <osmocom/abis/ipa.h>
+
+#include <openssl/rand.h>
+
+#include "../../bscconfig.h"
+
+#define SCCP_CLOSE_TIME 20
+#define SCCP_CLOSE_TIME_TIMEOUT 19
+
+static const char *config_file = "bsc-nat.cfg";
+static struct in_addr local_addr;
+static struct osmo_fd bsc_listen;
+static const char *msc_ip = NULL;
+static struct osmo_timer_list sccp_close;
+static int daemonize = 0;
+
+const char *openbsc_copyright =
+	"Copyright (C) 2010 Holger Hans Peter Freyther and On-Waves\r\n"
+	"License AGPLv3+: GNU AGPL version 3 or later <http://gnu.org/licenses/agpl-3.0.html>\r\n"
+	"This is free software: you are free to change and redistribute it.\r\n"
+	"There is NO WARRANTY, to the extent permitted by law.\r\n";
+
+static struct bsc_nat *nat;
+static void bsc_send_data(struct bsc_connection *bsc, const uint8_t *data, unsigned int length, int);
+static void msc_send_reset(struct bsc_msc_connection *con);
+static void bsc_stat_reject(int filter, struct bsc_connection *bsc, int normal);
+
+struct bsc_config *bsc_config_num(struct bsc_nat *nat, int num)
+{
+	struct bsc_config *conf;
+
+	llist_for_each_entry(conf, &nat->bsc_configs, entry)
+		if (conf->nr == num)
+			return conf;
+
+	return NULL;
+}
+
+static void queue_for_msc(struct bsc_msc_connection *con, struct msgb *msg)
+{
+	if (!con) {
+		LOGP(DLINP, LOGL_ERROR, "No MSC Connection assigned. Check your code.\n");
+		msgb_free(msg);
+		return;
+	}
+
+
+	if (osmo_wqueue_enqueue(&con->write_queue, msg) != 0) {
+		LOGP(DLINP, LOGL_ERROR, "Failed to enqueue the write.\n");
+		msgb_free(msg);
+	}
+}
+
+static void send_reset_ack(struct bsc_connection *bsc)
+{
+	static const uint8_t gsm_reset_ack[] = {
+		0x09, 0x00, 0x03, 0x07, 0x0b, 0x04, 0x43, 0x01,
+		0x00, 0xfe, 0x04, 0x43, 0x5c, 0x00, 0xfe, 0x03,
+		0x00, 0x01, 0x31,
+	};
+
+	bsc_send_data(bsc, gsm_reset_ack, sizeof(gsm_reset_ack), IPAC_PROTO_SCCP);
+}
+
+static void send_ping(struct bsc_connection *bsc)
+{
+	static const uint8_t id_ping[] = {
+		IPAC_MSGT_PING,
+	};
+
+	bsc_send_data(bsc, id_ping, sizeof(id_ping), IPAC_PROTO_IPACCESS);
+}
+
+static void send_pong(struct bsc_connection *bsc)
+{
+	static const uint8_t id_pong[] = {
+		IPAC_MSGT_PONG,
+	};
+
+	bsc_send_data(bsc, id_pong, sizeof(id_pong), IPAC_PROTO_IPACCESS);
+}
+
+static void bsc_pong_timeout(void *_bsc)
+{
+	struct bsc_connection *bsc = _bsc;
+
+	LOGP(DNAT, LOGL_ERROR, "BSC Nr: %d PONG timeout.\n", bsc->cfg->nr);
+	bsc_close_connection(bsc);
+}
+
+static void bsc_ping_timeout(void *_bsc)
+{
+	struct bsc_connection *bsc = _bsc;
+
+	if (bsc->nat->ping_timeout < 0)
+		return;
+
+	send_ping(bsc);
+
+	/* send another ping in 20 seconds */
+	osmo_timer_schedule(&bsc->ping_timeout, bsc->nat->ping_timeout, 0);
+
+	/* also start a pong timer */
+	osmo_timer_schedule(&bsc->pong_timeout, bsc->nat->pong_timeout, 0);
+}
+
+static void start_ping_pong(struct bsc_connection *bsc)
+{
+	osmo_timer_setup(&bsc->pong_timeout, bsc_pong_timeout, bsc);
+	osmo_timer_setup(&bsc->ping_timeout, bsc_ping_timeout, bsc);
+
+	bsc_ping_timeout(bsc);
+}
+
+static void send_id_ack(struct bsc_connection *bsc)
+{
+	static const uint8_t id_ack[] = {
+		IPAC_MSGT_ID_ACK
+	};
+
+	bsc_send_data(bsc, id_ack, sizeof(id_ack), IPAC_PROTO_IPACCESS);
+}
+
+static void send_id_req(struct bsc_nat *nat, struct bsc_connection *bsc)
+{
+	static const uint8_t s_id_req[] = {
+		IPAC_MSGT_ID_GET,
+		0x01, IPAC_IDTAG_UNIT,
+		0x01, IPAC_IDTAG_MACADDR,
+		0x01, IPAC_IDTAG_LOCATION1,
+		0x01, IPAC_IDTAG_LOCATION2,
+		0x01, IPAC_IDTAG_EQUIPVERS,
+		0x01, IPAC_IDTAG_SWVERSION,
+		0x01, IPAC_IDTAG_UNITNAME,
+		0x01, IPAC_IDTAG_SERNR,
+	};
+
+	uint8_t *mrand;
+	uint8_t id_req[sizeof(s_id_req) + (2+16)];
+	uint8_t *buf = &id_req[sizeof(s_id_req)];
+
+	/* copy the static data */
+	memcpy(id_req, s_id_req, sizeof(s_id_req));
+
+	/* put the RAND with length, tag, value */
+	buf = v_put(buf, 0x11);
+	buf = v_put(buf, 0x23);
+	mrand = bsc->last_rand;
+
+	if (RAND_bytes(mrand, 16) != 1)
+		goto failed_random;
+
+	memcpy(buf, mrand, 16);
+	buf += 16;
+
+	bsc_send_data(bsc, id_req, sizeof(id_req), IPAC_PROTO_IPACCESS);
+	return;
+
+failed_random:
+	/* the timeout will trigger and close this connection */
+	LOGP(DNAT, LOGL_ERROR, "Failed to read from urandom.\n");
+	return;
+}
+
+static struct msgb *nat_create_rlsd(struct nat_sccp_connection *conn)
+{
+	struct sccp_connection_released *rel;
+	struct msgb *msg;
+
+	msg = msgb_alloc_headroom(4096, 128, "rlsd");
+	if (!msg) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate released.\n");
+		return NULL;
+	}
+
+	msg->l2h = msgb_put(msg, sizeof(*rel));
+	rel = (struct sccp_connection_released *) msg->l2h;
+	rel->type = SCCP_MSG_TYPE_RLSD;
+	rel->release_cause = SCCP_RELEASE_CAUSE_SCCP_FAILURE;
+	rel->destination_local_reference = conn->remote_ref;
+	rel->source_local_reference = conn->patched_ref;
+
+	return msg;
+}
+
+static void nat_send_rlsd_ussd(struct bsc_nat *nat, struct nat_sccp_connection *conn)
+{
+	struct msgb *msg;
+
+	if (!nat->ussd_con)
+		return;
+
+	msg = nat_create_rlsd(conn);
+	if (!msg)
+		return;
+
+	bsc_do_write(&nat->ussd_con->queue, msg, IPAC_PROTO_SCCP);
+}
+
+static void nat_send_rlsd_msc(struct nat_sccp_connection *conn)
+{
+	struct msgb *msg;
+
+	msg = nat_create_rlsd(conn);
+	if (!msg)
+		return;
+
+	ipa_prepend_header(msg, IPAC_PROTO_SCCP);
+	queue_for_msc(conn->msc_con, msg);
+}
+
+static void nat_send_rlsd_bsc(struct nat_sccp_connection *conn)
+{
+	struct msgb *msg;
+	struct sccp_connection_released *rel;
+
+	msg = msgb_alloc_headroom(4096, 128, "rlsd");
+	if (!msg) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate clear command.\n");
+		return;
+	}
+
+	msg->l2h = msgb_put(msg, sizeof(*rel));
+	rel = (struct sccp_connection_released *) msg->l2h;
+	rel->type = SCCP_MSG_TYPE_RLSD;
+	rel->release_cause = SCCP_RELEASE_CAUSE_SCCP_FAILURE;
+	rel->destination_local_reference = conn->real_ref;
+	rel->source_local_reference = conn->remote_ref;
+
+	bsc_write(conn->bsc, msg, IPAC_PROTO_SCCP);
+}
+
+static struct msgb *nat_creat_clrc(struct nat_sccp_connection *conn, uint8_t cause)
+{
+	struct msgb *msg;
+	struct msgb *sccp;
+
+	msg = gsm0808_create_clear_command(cause);
+	if (!msg) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate clear command.\n");
+		return NULL;
+	}
+
+	sccp = sccp_create_dt1(&conn->real_ref, msg->data, msg->len);
+	if (!sccp) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate SCCP msg.\n");
+		msgb_free(msg);
+		return NULL;
+	}
+
+	msgb_free(msg);
+	return sccp;
+}
+
+static int nat_send_clrc_bsc(struct nat_sccp_connection *conn)
+{
+	struct msgb *sccp;
+
+	sccp = nat_creat_clrc(conn, 0x20);
+	if (!sccp)
+		return -1;
+	return bsc_write(conn->bsc, sccp, IPAC_PROTO_SCCP);
+}
+
+static void nat_send_rlc(struct bsc_msc_connection *msc_con,
+			 struct sccp_source_reference *src,
+			 struct sccp_source_reference *dst)
+{
+	struct sccp_connection_release_complete *rlc;
+	struct msgb *msg;
+
+	msg = msgb_alloc_headroom(4096, 128, "rlc");
+	if (!msg) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to sccp rlc.\n");
+		return;
+	}
+
+	msg->l2h = msgb_put(msg, sizeof(*rlc));
+	rlc = (struct sccp_connection_release_complete *) msg->l2h;
+	rlc->type = SCCP_MSG_TYPE_RLC;
+	rlc->destination_local_reference = *dst;
+	rlc->source_local_reference = *src;
+
+	ipa_prepend_header(msg, IPAC_PROTO_SCCP);
+
+	queue_for_msc(msc_con, msg);
+}
+
+static void send_mgcp_reset(struct bsc_connection *bsc)
+{
+	static const uint8_t mgcp_reset[] = {
+	    "RSIP 1 13@mgw MGCP 1.0\r\n"
+	};
+
+	bsc_write_mgcp(bsc, mgcp_reset, sizeof mgcp_reset - 1);
+}
+
+void bsc_nat_send_mgcp_to_msc(struct bsc_nat *nat, struct msgb *msg)
+{
+	ipa_prepend_header(msg, IPAC_PROTO_MGCP_OLD);
+	queue_for_msc(nat->msc_con, msg);
+}
+
+/*
+ * Below is the handling of messages coming
+ * from the MSC and need to be forwarded to
+ * a real BSC.
+ */
+static void initialize_msc_if_needed(struct bsc_msc_connection *msc_con)
+{
+	if (msc_con->first_contact)
+		return;
+
+	msc_con->first_contact = 1;
+	msc_send_reset(msc_con);
+}
+
+static void send_id_get_response(struct bsc_msc_connection *msc_con)
+{
+	struct msgb *msg = bsc_msc_id_get_resp(0, nat->token, NULL, 0);
+	if (!msg)
+		return;
+
+	ipa_prepend_header(msg, IPAC_PROTO_IPACCESS);
+	queue_for_msc(msc_con, msg);
+}
+
+/*
+ * Currently we are lacking refcounting so we need to copy each message.
+ */
+static void bsc_send_data(struct bsc_connection *bsc, const uint8_t *data, unsigned int length, int proto)
+{
+	struct msgb *msg;
+
+	if (length > 4096 - 128) {
+		LOGP(DLINP, LOGL_ERROR, "Can not send message of that size.\n");
+		return;
+	}
+
+	msg = msgb_alloc_headroom(4096, 128, "to-bsc");
+	if (!msg) {
+		LOGP(DLINP, LOGL_ERROR, "Failed to allocate memory for BSC msg.\n");
+		return;
+	}
+
+	msg->l2h = msgb_put(msg, length);
+	memcpy(msg->data, data, length);
+
+	bsc_write(bsc, msg, proto);
+}
+
+/*
+ * Update the release statistics
+ */
+static void bsc_stat_reject(int filter, struct bsc_connection *bsc, int normal)
+{
+	if (!bsc->cfg) {
+		LOGP(DNAT, LOGL_ERROR, "BSC is not authenticated.");
+		return;
+	}
+
+	if (filter >= 0) {
+		LOGP(DNAT, LOGL_ERROR, "Connection was not rejected");
+		return;
+	}
+
+	if (filter == -1)
+		rate_ctr_inc(&bsc->cfg->stats.ctrg->ctr[BCFG_CTR_ILL_PACKET]);
+	else if (normal)
+		rate_ctr_inc(&bsc->cfg->stats.ctrg->ctr[BCFG_CTR_REJECTED_MSG]);
+	else
+		rate_ctr_inc(&bsc->cfg->stats.ctrg->ctr[BCFG_CTR_REJECTED_CR]);
+}
+
+/*
+ * Release an established connection. We will have to release it to the BSC
+ * and to the network and we do it the following way.
+ * 1.) Give up on the MSC side
+ *  1.1) Send a RLSD message, it is a bit non standard but should work, we
+ *       ignore the RLC... we might complain about it. Other options would
+ *       be to send a Release Request, handle the Release Complete..
+ *  1.2) Mark the data structure to be con_local and wait for 2nd
+ *
+ * 2.) Give up on the BSC side
+ *  2.1) Depending on the con type reject the service, or just close it
+ */
+static void bsc_send_con_release(struct bsc_connection *bsc,
+		struct nat_sccp_connection *con,
+		struct bsc_filter_reject_cause *cause)
+{
+	struct msgb *rlsd;
+	/* 1. release the network */
+	rlsd = sccp_create_rlsd(&con->patched_ref, &con->remote_ref,
+				SCCP_RELEASE_CAUSE_END_USER_ORIGINATED);
+	if (!rlsd)
+		LOGP(DNAT, LOGL_ERROR, "Failed to create RLSD message.\n");
+	else {
+		ipa_prepend_header(rlsd, IPAC_PROTO_SCCP);
+		queue_for_msc(con->msc_con, rlsd);
+	}
+	con->con_local = NAT_CON_END_LOCAL;
+	con->msc_con = NULL;
+
+	/* 2. release the BSC side */
+	if (con->filter_state.con_type == FLT_CON_TYPE_LU) {
+		struct msgb *payload, *udt;
+		payload = gsm48_create_loc_upd_rej(cause->lu_reject_cause);
+
+		if (payload) {
+			gsm0808_prepend_dtap_header(payload, 0);
+			udt = sccp_create_dt1(&con->real_ref, payload->data, payload->len);
+			if (udt)
+				bsc_write(bsc, udt, IPAC_PROTO_SCCP);
+			else
+				LOGP(DNAT, LOGL_ERROR, "Failed to create DT1\n");
+
+			msgb_free(payload);
+		} else {
+			LOGP(DNAT, LOGL_ERROR, "Failed to allocate LU Reject.\n");
+		}
+	}
+
+	nat_send_clrc_bsc(con);
+
+	rlsd = sccp_create_rlsd(&con->remote_ref, &con->real_ref,
+				SCCP_RELEASE_CAUSE_END_USER_ORIGINATED);
+	if (!rlsd) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate RLSD for the BSC.\n");
+		sccp_connection_destroy(con);
+		return;
+	}
+
+	con->filter_state.con_type = FLT_CON_TYPE_LOCAL_REJECT;
+	bsc_write(bsc, rlsd, IPAC_PROTO_SCCP);
+}
+
+static void bsc_send_con_refuse(struct bsc_connection *bsc,
+			struct bsc_nat_parsed *parsed, int con_type,
+			struct bsc_filter_reject_cause *cause)
+{
+	struct msgb *payload;
+	struct msgb *refuse;
+
+	if (con_type == FLT_CON_TYPE_LU)
+		payload = gsm48_create_loc_upd_rej(cause->lu_reject_cause);
+	else if (con_type == FLT_CON_TYPE_CM_SERV_REQ || con_type == FLT_CON_TYPE_SSA)
+		payload = gsm48_create_mm_serv_rej(cause->cm_reject_cause);
+	else {
+		LOGP(DNAT, LOGL_ERROR, "Unknown connection type: %d\n", con_type);
+		payload = NULL;
+	}
+
+	/*
+	 * Some BSCs do not handle the payload inside a SCCP CREF msg
+	 * so we will need to:
+	 * 1.) Allocate a local connection and mark it as local..
+	 * 2.) queue data for downstream.. and the RLC should delete everything
+	 */
+	if (payload) {
+		struct msgb *cc, *udt, *clear, *rlsd;
+		struct nat_sccp_connection *con;
+		con = create_sccp_src_ref(bsc, parsed);
+		if (!con)
+			goto send_refuse;
+
+		/* declare it local and assign a unique remote_ref */
+		con->filter_state.con_type = FLT_CON_TYPE_LOCAL_REJECT;
+		con->con_local = NAT_CON_END_LOCAL;
+		con->has_remote_ref = 1;
+		con->remote_ref = con->patched_ref;
+
+		/* 1. create a confirmation */
+		cc = sccp_create_cc(&con->remote_ref, &con->real_ref);
+		if (!cc)
+			goto send_refuse;
+
+		/* 2. create the DT1 */
+		gsm0808_prepend_dtap_header(payload, 0);
+		udt = sccp_create_dt1(&con->real_ref, payload->data, payload->len);
+		if (!udt) {
+			msgb_free(cc);
+			goto send_refuse;
+		}
+
+		/* 3. send a Clear Command */
+		clear = nat_creat_clrc(con, 0x20);
+		if (!clear) {
+			msgb_free(cc);
+			msgb_free(udt);
+			goto send_refuse;
+		}
+
+		/* 4. send a RLSD */
+		rlsd = sccp_create_rlsd(&con->remote_ref, &con->real_ref,
+					SCCP_RELEASE_CAUSE_END_USER_ORIGINATED);
+		if (!rlsd) {
+			msgb_free(cc);
+			msgb_free(udt);
+			msgb_free(clear);
+			goto send_refuse;
+		}
+
+		bsc_write(bsc, cc, IPAC_PROTO_SCCP);
+		bsc_write(bsc, udt, IPAC_PROTO_SCCP);
+		bsc_write(bsc, clear, IPAC_PROTO_SCCP);
+		bsc_write(bsc, rlsd, IPAC_PROTO_SCCP);
+		msgb_free(payload);
+		return;
+	}
+
+
+send_refuse:
+	if (payload)
+		msgb_free(payload);
+
+	refuse = sccp_create_refuse(parsed->src_local_ref,
+				    SCCP_REFUSAL_SCCP_FAILURE, NULL, 0);
+	if (!refuse) {
+		LOGP(DNAT, LOGL_ERROR,
+		     "Creating refuse msg failed for SCCP 0x%x on BSC Nr: %d.\n",
+		      sccp_src_ref_to_int(parsed->src_local_ref), bsc->cfg->nr);
+		return;
+	}
+
+	bsc_write(bsc, refuse, IPAC_PROTO_SCCP);
+}
+
+static void bsc_nat_send_paging(struct bsc_connection *bsc, struct msgb *msg)
+{
+	if (bsc->cfg->forbid_paging) {
+		LOGP(DNAT, LOGL_DEBUG, "Paging forbidden for BTS: %d\n", bsc->cfg->nr);
+		return;
+	}
+
+	bsc_send_data(bsc, msg->l2h, msgb_l2len(msg), IPAC_PROTO_SCCP);
+}
+
+static void bsc_nat_handle_paging(struct bsc_nat *nat, struct msgb *msg)
+{
+	struct bsc_connection *bsc;
+	const uint8_t *paging_start;
+	int paging_length, i, ret;
+
+	ret = bsc_nat_find_paging(msg, &paging_start, &paging_length);
+	if (ret != 0) {
+		LOGP(DNAT, LOGL_ERROR, "Could not parse paging message: %d\n", ret);
+		return;
+	}
+
+	/* This is quite expensive now */
+	for (i = 0; i < paging_length; i += 2) {
+		unsigned int _lac = ntohs(*(unsigned int *) &paging_start[i]);
+		unsigned int paged = 0;
+		llist_for_each_entry(bsc, &nat->bsc_connections, list_entry) {
+			if (!bsc->cfg)
+				continue;
+			if (!bsc->authenticated)
+				continue;
+			if (!bsc_config_handles_lac(bsc->cfg, _lac))
+				continue;
+			bsc_nat_send_paging(bsc, msg);
+			paged += 1;
+		}
+
+		/* highlight a possible config issue */
+		if (paged == 0)
+			LOGP(DNAT, LOGL_ERROR, "No BSC for LAC %d/0x%d\n", _lac, _lac);
+
+	}
+}
+
+
+/*
+ * Update the auth status. This can be either a CIPHER MODE COMMAND or
+ * a CM Serivce Accept. Maybe also LU Accept or such in the future.
+ */
+static void update_con_authorize(struct nat_sccp_connection *con,
+				 struct bsc_nat_parsed *parsed,
+				 struct msgb *msg)
+{
+	if (!con)
+		return;
+	if (con->authorized)
+		return;
+
+	if (parsed->bssap == BSSAP_MSG_BSS_MANAGEMENT &&
+	    parsed->gsm_type == BSS_MAP_MSG_CIPHER_MODE_CMD) {
+		con->authorized = 1;
+	} else if (parsed->bssap == BSSAP_MSG_DTAP) {
+		uint8_t msg_type, proto;
+		uint32_t len;
+		struct gsm48_hdr *hdr48;
+		hdr48 = bsc_unpack_dtap(parsed, msg, &len);
+		if (!hdr48)
+			return;
+
+		proto = gsm48_hdr_pdisc(hdr48);
+		msg_type = gsm48_hdr_msg_type(hdr48);
+		if (proto == GSM48_PDISC_MM &&
+		    msg_type == GSM48_MT_MM_CM_SERV_ACC)
+			con->authorized = 1;
+	}
+}
+
+static int forward_sccp_to_bts(struct bsc_msc_connection *msc_con, struct msgb *msg)
+{
+	struct nat_sccp_connection *con = NULL;
+	struct bsc_connection *bsc;
+	struct bsc_nat_parsed *parsed;
+	int proto;
+
+	/* filter, drop, patch the message? */
+	parsed = bsc_nat_parse(msg);
+	if (!parsed) {
+		LOGP(DNAT, LOGL_ERROR, "Can not parse msg from BSC.\n");
+		return -1;
+	}
+
+	if (bsc_nat_filter_ipa(DIR_BSC, msg, parsed))
+		goto exit;
+
+	proto = parsed->ipa_proto;
+
+	/* Route and modify the SCCP packet */
+	if (proto == IPAC_PROTO_SCCP) {
+		switch (parsed->sccp_type) {
+		case SCCP_MSG_TYPE_UDT:
+			/* forward UDT messages to every BSC */
+			goto send_to_all;
+			break;
+		case SCCP_MSG_TYPE_RLSD:
+		case SCCP_MSG_TYPE_CREF:
+		case SCCP_MSG_TYPE_DT1:
+		case SCCP_MSG_TYPE_IT:
+			con = patch_sccp_src_ref_to_bsc(msg, parsed, nat);
+			if (parsed->gsm_type == BSS_MAP_MSG_ASSIGMENT_RQST) {
+				osmo_counter_inc(nat->stats.sccp.calls);
+
+				if (con) {
+					struct rate_ctr_group *ctrg;
+					ctrg = con->bsc->cfg->stats.ctrg;
+					rate_ctr_inc(&ctrg->ctr[BCFG_CTR_SCCP_CALLS]);
+					if (bsc_mgcp_assign_patch(con, msg) != 0)
+						LOGP(DNAT, LOGL_ERROR, "Failed to assign...\n");
+				} else
+					LOGP(DNAT, LOGL_ERROR, "Assignment command but no BSC.\n");
+			} else if (con && con->con_local == NAT_CON_END_USSD &&
+				   parsed->gsm_type == BSS_MAP_MSG_CLEAR_CMD) {
+				LOGP(DNAT, LOGL_NOTICE, "Clear Command for USSD Connection. Ignoring.\n");
+				con = NULL;
+			}
+			break;
+		case SCCP_MSG_TYPE_CC:
+			con = patch_sccp_src_ref_to_bsc(msg, parsed, nat);
+			if (!con || update_sccp_src_ref(con, parsed) != 0)
+				goto exit;
+			break;
+		case SCCP_MSG_TYPE_RLC:
+			LOGP(DNAT, LOGL_ERROR, "Unexpected release complete from MSC.\n");
+			goto exit;
+			break;
+		case SCCP_MSG_TYPE_CR:
+			/* MSC never opens a SCCP connection, fall through */
+		default:
+			goto exit;
+		}
+
+		if (!con && parsed->sccp_type == SCCP_MSG_TYPE_RLSD) {
+			LOGP(DNAT, LOGL_NOTICE, "Sending fake RLC on RLSD message to network.\n");
+			/* Exchange src/dest for the reply */
+			nat_send_rlc(msc_con, &parsed->original_dest_ref,
+					parsed->src_local_ref);
+		} else if (!con)
+			LOGP(DNAT, LOGL_ERROR, "Unknown connection for msg type: 0x%x from the MSC.\n", parsed->sccp_type);
+	}
+
+	if (!con) {
+		talloc_free(parsed);
+		return -1;
+	}
+	if (!con->bsc->authenticated) {
+		talloc_free(parsed);
+		LOGP(DNAT, LOGL_ERROR, "Selected BSC not authenticated.\n");
+		return -1;
+	}
+
+	update_con_authorize(con, parsed, msg);
+	talloc_free(parsed);
+
+	bsc_send_data(con->bsc, msg->l2h, msgb_l2len(msg), proto);
+	return 0;
+
+send_to_all:
+	/*
+	 * Filter Paging from the network. We do not want to send a PAGING
+	 * Command to every BSC in our network. We will analys the PAGING
+	 * message and then send it to the authenticated messages...
+	 */
+	if (parsed->ipa_proto == IPAC_PROTO_SCCP && parsed->gsm_type == BSS_MAP_MSG_PAGING) {
+		bsc_nat_handle_paging(nat, msg);
+		goto exit;
+	}
+	/* currently send this to every BSC connected */
+	llist_for_each_entry(bsc, &nat->bsc_connections, list_entry) {
+		if (!bsc->authenticated)
+			continue;
+
+		bsc_send_data(bsc, msg->l2h, msgb_l2len(msg), parsed->ipa_proto);
+	}
+
+exit:
+	talloc_free(parsed);
+	return 0;
+}
+
+static void msc_connection_was_lost(struct bsc_msc_connection *con)
+{
+	struct bsc_connection *bsc, *tmp;
+
+	LOGP(DMSC, LOGL_ERROR, "Closing all connections downstream.\n");
+	llist_for_each_entry_safe(bsc, tmp, &nat->bsc_connections, list_entry)
+		bsc_close_connection(bsc);
+
+	bsc_mgcp_free_endpoints(nat);
+	bsc_msc_schedule_connect(con);
+}
+
+static void msc_connection_connected(struct bsc_msc_connection *con)
+{
+	osmo_counter_inc(nat->stats.msc.reconn);
+}
+
+static void msc_send_reset(struct bsc_msc_connection *msc_con)
+{
+	static const uint8_t reset[] = {
+		0x00, 0x12, 0xfd,
+		0x09, 0x00, 0x03, 0x05, 0x07, 0x02, 0x42, 0xfe,
+		0x02, 0x42, 0xfe, 0x06, 0x00, 0x04, 0x30, 0x04,
+		0x01, 0x20
+	};
+
+	struct msgb *msg;
+
+	msg = msgb_alloc_headroom(4096, 128, "08.08 reset");
+	if (!msg) {
+		LOGP(DMSC, LOGL_ERROR, "Failed to allocate reset msg.\n");
+		return;
+	}
+
+	msg->l2h = msgb_put(msg, sizeof(reset));
+	memcpy(msg->l2h, reset, msgb_l2len(msg));
+
+	queue_for_msc(msc_con, msg);
+
+	LOGP(DMSC, LOGL_NOTICE, "Scheduled GSM0808 reset msg for the MSC.\n");
+}
+
+static int ipaccess_msc_read_cb(struct osmo_fd *bfd)
+{
+	struct bsc_msc_connection *msc_con;
+	struct msgb *msg = NULL;
+	struct ipaccess_head *hh;
+	int ret;
+
+	msc_con = (struct bsc_msc_connection *) bfd->data;
+
+	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &msc_con->pending_msg);
+	if (ret <= 0) {
+		if (ret == -EAGAIN)
+			return 0;
+		if (ret == 0)
+			LOGP(DNAT, LOGL_FATAL,
+				"The connection the MSC(%s) was lost, exiting\n",
+				msc_con->name);
+		else
+			LOGP(DNAT, LOGL_ERROR,
+				"Failed to parse ip access message on %s: %d\n",
+				msc_con->name, ret);
+
+		bsc_msc_lost(msc_con);
+		return -1;
+	}
+
+	LOGP(DNAT, LOGL_DEBUG,
+		"MSG from MSC(%s): %s proto: %d\n", msc_con->name,
+		osmo_hexdump(msg->data, msg->len), msg->l2h[0]);
+
+	/* handle base message handling */
+	hh = (struct ipaccess_head *) msg->data;
+
+	/* initialize the networking. This includes sending a GSM08.08 message */
+	if (hh->proto == IPAC_PROTO_IPACCESS) {
+		ipa_ccm_rcvmsg_base(msg, bfd);
+		if (msg->l2h[0] == IPAC_MSGT_ID_ACK)
+			initialize_msc_if_needed(msc_con);
+		else if (msg->l2h[0] == IPAC_MSGT_ID_GET)
+			send_id_get_response(msc_con);
+	} else if (hh->proto == IPAC_PROTO_SCCP) {
+		forward_sccp_to_bts(msc_con, msg);
+	} else if (hh->proto == IPAC_PROTO_MGCP_OLD) {
+		bsc_nat_handle_mgcp(nat, msg);
+	}
+
+	msgb_free(msg);
+	return 0;
+}
+
+static int ipaccess_msc_write_cb(struct osmo_fd *bfd, struct msgb *msg)
+{
+	int rc;
+	rc = write(bfd->fd, msg->data, msg->len);
+
+	if (rc != msg->len) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to write MSG to MSC.\n");
+		return -1;
+	}
+
+	return rc;
+}
+
+/*
+ * Below is the handling of messages coming
+ * from the BSC and need to be forwarded to
+ * a real BSC.
+ */
+
+/*
+ * Remove the connection from the connections list,
+ * remove it from the patching of SCCP header lists
+ * as well. Maybe in the future even close connection..
+ */
+void bsc_close_connection(struct bsc_connection *connection)
+{
+	struct nat_sccp_connection *sccp_patch, *tmp;
+	struct bsc_cmd_list *cmd_entry, *cmd_tmp;
+	struct rate_ctr *ctr = NULL;
+
+	/* stop the timeout timer */
+	osmo_timer_del(&connection->id_timeout);
+	osmo_timer_del(&connection->ping_timeout);
+	osmo_timer_del(&connection->pong_timeout);
+
+	if (connection->cfg)
+		ctr = &connection->cfg->stats.ctrg->ctr[BCFG_CTR_DROPPED_SCCP];
+
+	/* remove all SCCP connections */
+	llist_for_each_entry_safe(sccp_patch, tmp, &nat->sccp_connections, list_entry) {
+		if (sccp_patch->bsc != connection)
+			continue;
+
+		if (ctr)
+			rate_ctr_inc(ctr);
+		if (sccp_patch->has_remote_ref) {
+			if (sccp_patch->con_local == NAT_CON_END_MSC)
+				nat_send_rlsd_msc(sccp_patch);
+			else if (sccp_patch->con_local == NAT_CON_END_USSD)
+				nat_send_rlsd_ussd(nat, sccp_patch);
+		}
+
+		sccp_connection_destroy(sccp_patch);
+	}
+
+	/* Reply to all outstanding commands */
+	llist_for_each_entry_safe(cmd_entry, cmd_tmp, &connection->cmd_pending, list_entry) {
+		cmd_entry->cmd->type = CTRL_TYPE_ERROR;
+		cmd_entry->cmd->reply = "BSC closed the connection";
+		ctrl_cmd_send(&cmd_entry->ccon->write_queue, cmd_entry->cmd);
+		bsc_nat_ctrl_del_pending(cmd_entry);
+	}
+
+	/* close endpoints allocated by this BSC */
+	bsc_mgcp_clear_endpoints_for(connection);
+
+	osmo_fd_unregister(&connection->write_queue.bfd);
+	close(connection->write_queue.bfd.fd);
+	osmo_wqueue_clear(&connection->write_queue);
+	llist_del(&connection->list_entry);
+
+	if (connection->pending_msg) {
+		LOGP(DNAT, LOGL_ERROR, "Dropping partial message on connection %d.\n",
+		     connection->cfg ? connection->cfg->nr : -1);
+		msgb_free(connection->pending_msg);
+		connection->pending_msg = NULL;
+	}
+
+	talloc_free(connection);
+}
+
+static void bsc_maybe_close(struct bsc_connection *bsc)
+{
+	struct nat_sccp_connection *sccp;
+	if (!bsc->nat->blocked)
+		return;
+
+	/* are there any connections left */
+	llist_for_each_entry(sccp, &bsc->nat->sccp_connections, list_entry)
+		if (sccp->bsc == bsc)
+			return;
+
+	/* nothing left, close the BSC */
+	LOGP(DNAT, LOGL_NOTICE, "Cleaning up BSC %d in blocking mode.\n",
+	     bsc->cfg ? bsc->cfg->nr : -1);
+	bsc_close_connection(bsc);
+}
+
+static void ipaccess_close_bsc(void *data)
+{
+	struct sockaddr_in sock;
+	socklen_t len = sizeof(sock);
+	struct bsc_connection *conn = data;
+
+
+	getpeername(conn->write_queue.bfd.fd, (struct sockaddr *) &sock, &len);
+	LOGP(DNAT, LOGL_ERROR, "BSC on %s didn't respond to identity request. Closing.\n",
+	     inet_ntoa(sock.sin_addr));
+	bsc_close_connection(conn);
+}
+
+static int verify_key(struct bsc_connection *conn, struct bsc_config *conf, const uint8_t *key, const int keylen)
+{
+	struct osmo_auth_vector vec;
+
+	struct osmo_sub_auth_data auth = {
+		.type		= OSMO_AUTH_TYPE_GSM,
+		.algo		= OSMO_AUTH_ALG_MILENAGE,
+	};
+
+	/* expect a specific keylen */
+	if (keylen != 8) {
+		LOGP(DNAT, LOGL_ERROR, "Key length is wrong: %d for bsc nr %d\n",
+			keylen, conf->nr);
+		return 0;
+	}
+
+	memcpy(auth.u.umts.opc, conf->key, 16);
+	memcpy(auth.u.umts.k, conf->key, 16);
+	memset(auth.u.umts.amf, 0, 2);
+	auth.u.umts.sqn = 0;
+
+	memset(&vec, 0, sizeof(vec));
+	osmo_auth_gen_vec(&vec, &auth, conn->last_rand);
+
+	if (vec.res_len != 8) {
+		LOGP(DNAT, LOGL_ERROR, "Res length is wrong: %d for bsc nr %d\n",
+			vec.res_len, conf->nr);
+		return 0;
+	}
+
+	return osmo_constant_time_cmp(vec.res, key, 8) == 0;
+}
+
+static void ipaccess_auth_bsc(struct tlv_parsed *tvp, struct bsc_connection *bsc)
+{
+	struct bsc_config *conf;
+	const char *token = (const char *) TLVP_VAL(tvp, IPAC_IDTAG_UNITNAME);
+	int len = TLVP_LEN(tvp, IPAC_IDTAG_UNITNAME);
+	const uint8_t *xres = TLVP_VAL(tvp, 0x24);
+	const int xlen = TLVP_LEN(tvp, 0x24);
+
+	if (bsc->cfg) {
+		LOGP(DNAT, LOGL_ERROR, "Reauth on fd %d bsc nr %d\n",
+		     bsc->write_queue.bfd.fd, bsc->cfg->nr);
+		return;
+	}
+
+	if (len <= 0) {
+		LOGP(DNAT, LOGL_ERROR, "Token with length zero on fd: %d\n",
+			bsc->write_queue.bfd.fd);
+		return;
+	}
+
+	if (token[len - 1] != '\0') {
+		LOGP(DNAT, LOGL_ERROR, "Token not null terminated on fd: %d\n",
+			bsc->write_queue.bfd.fd);
+		return;
+	}
+
+	/*
+	 * New systems have fixed the structure of the message but
+	 * we need to support old ones too.
+	 */
+	if (len >= 2 && token[len - 2] == '\0')
+		len -= 1;
+
+	conf = bsc_config_by_token(bsc->nat, token, len);
+	if (!conf) {
+		LOGP(DNAT, LOGL_ERROR,
+			"No bsc found for token '%s' len %d on fd: %d.\n", token,
+			bsc->write_queue.bfd.fd, len);
+		bsc_close_connection(bsc);
+		return;
+	}
+
+	/* We have set a key and expect it to be present */
+	if (conf->key_present && !verify_key(bsc, conf, xres, xlen - 1)) {
+		LOGP(DNAT, LOGL_ERROR,
+			"Wrong key for bsc nr %d fd: %d.\n", conf->nr,
+			bsc->write_queue.bfd.fd);
+		bsc_close_connection(bsc);
+		return;
+	}
+
+	rate_ctr_inc(&conf->stats.ctrg->ctr[BCFG_CTR_NET_RECONN]);
+	bsc->authenticated = 1;
+	bsc->cfg = conf;
+	osmo_timer_del(&bsc->id_timeout);
+	LOGP(DNAT, LOGL_NOTICE, "Authenticated bsc nr: %d on fd %d\n",
+		conf->nr, bsc->write_queue.bfd.fd);
+	start_ping_pong(bsc);
+}
+
+static void handle_con_stats(struct nat_sccp_connection *con)
+{
+	struct rate_ctr_group *ctrg;
+	int id = bsc_conn_type_to_ctr(con);
+
+	if (id == -1)
+		return;
+
+	if (!con->bsc || !con->bsc->cfg)
+		return;
+
+	ctrg = con->bsc->cfg->stats.ctrg;
+	rate_ctr_inc(&ctrg->ctr[id]);
+}
+
+static int forward_sccp_to_msc(struct bsc_connection *bsc, struct msgb *msg)
+{
+	int con_filter = 0;
+	char *imsi = NULL;
+	struct bsc_msc_connection *con_msc = NULL;
+	struct bsc_connection *con_bsc = NULL;
+	int con_type;
+	struct bsc_nat_parsed *parsed;
+	struct bsc_filter_reject_cause cause;
+
+	/* Parse and filter messages */
+	parsed = bsc_nat_parse(msg);
+	if (!parsed) {
+		LOGP(DNAT, LOGL_ERROR, "Can not parse msg from BSC.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	if (bsc_nat_filter_ipa(DIR_MSC, msg, parsed))
+		goto exit;
+
+	/*
+	 * check authentication after filtering to not reject auth
+	 * responses coming from the BSC. We have to make sure that
+	 * nothing from the exit path will forward things to the MSC
+	 */
+	if (!bsc->authenticated) {
+		LOGP(DNAT, LOGL_ERROR, "BSC is not authenticated.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+
+	/* modify the SCCP entries */
+	if (parsed->ipa_proto == IPAC_PROTO_SCCP) {
+		int filter;
+		struct nat_sccp_connection *con;
+		switch (parsed->sccp_type) {
+		case SCCP_MSG_TYPE_CR:
+			memset(&cause, 0, sizeof(cause));
+			filter = bsc_nat_filter_sccp_cr(bsc, msg, parsed,
+						&con_type, &imsi, &cause);
+			if (filter < 0) {
+				if (imsi)
+					bsc_nat_inform_reject(bsc, imsi);
+				bsc_stat_reject(filter, bsc, 0);
+				goto exit3;
+			}
+
+			if (!create_sccp_src_ref(bsc, parsed))
+				goto exit2;
+			con = patch_sccp_src_ref_to_msc(msg, parsed, bsc);
+			OSMO_ASSERT(con);
+			con->msc_con = bsc->nat->msc_con;
+			con_msc = con->msc_con;
+			con->filter_state.con_type = con_type;
+			con->filter_state.imsi_checked = filter;
+			bsc_nat_extract_lac(bsc, con, parsed, msg);
+			if (imsi)
+				con->filter_state.imsi = talloc_steal(con, imsi);
+			imsi = NULL;
+			con_bsc = con->bsc;
+			handle_con_stats(con);
+			break;
+		case SCCP_MSG_TYPE_RLSD:
+		case SCCP_MSG_TYPE_CREF:
+		case SCCP_MSG_TYPE_DT1:
+		case SCCP_MSG_TYPE_CC:
+		case SCCP_MSG_TYPE_IT:
+			con = patch_sccp_src_ref_to_msc(msg, parsed, bsc);
+			if (con) {
+				/* only filter non local connections */
+				if (!con->con_local) {
+					memset(&cause, 0, sizeof(cause));
+					filter = bsc_nat_filter_dt(bsc, msg,
+							con, parsed, &cause);
+					if (filter < 0) {
+						if (con->filter_state.imsi)
+							bsc_nat_inform_reject(bsc,
+								con->filter_state.imsi);
+						bsc_stat_reject(filter, bsc, 1);
+						bsc_send_con_release(bsc, con, &cause);
+						con = NULL;
+						goto exit2;
+					}
+
+					/* hand data to a side channel */
+					if (bsc_ussd_check(con, parsed, msg) == 1) 
+						con->con_local = NAT_CON_END_USSD;
+
+					/*
+					 * Optionally rewrite setup message. This can
+					 * replace the msg and the parsed structure becomes
+					 * invalid.
+					 */
+					msg = bsc_nat_rewrite_msg(bsc->nat, msg, parsed,
+									con->filter_state.imsi);
+					talloc_free(parsed);
+					parsed = NULL;
+				} else if (con->con_local == NAT_CON_END_USSD) {
+					bsc_ussd_check(con, parsed, msg);
+				}
+
+				con_bsc = con->bsc;
+				con_msc = con->msc_con;
+				con_filter = con->con_local;
+			}
+
+			break;
+		case SCCP_MSG_TYPE_RLC:
+			con = patch_sccp_src_ref_to_msc(msg, parsed, bsc);
+			if (con) {
+				con_bsc = con->bsc;
+				con_msc = con->msc_con;
+				con_filter = con->con_local;
+			}
+			remove_sccp_src_ref(bsc, msg, parsed);
+			bsc_maybe_close(bsc);
+			break;
+		case SCCP_MSG_TYPE_UDT:
+			/* simply forward everything */
+			con = NULL;
+			break;
+		default:
+			LOGP(DNAT, LOGL_ERROR, "Not forwarding to msc sccp type: 0x%x\n", parsed->sccp_type);
+			con = NULL;
+			goto exit2;
+			break;
+		}
+        } else if (parsed->ipa_proto == IPAC_PROTO_MGCP_OLD) {
+                bsc_mgcp_forward(bsc, msg);
+                goto exit2;
+	} else {
+		LOGP(DNAT, LOGL_ERROR, "Not forwarding unknown stream id: 0x%x\n", parsed->ipa_proto);
+		goto exit2;
+	}
+
+	if (con_msc && con_bsc != bsc) {
+		LOGP(DNAT, LOGL_ERROR, "The connection belongs to a different BTS: input: %d con: %d\n",
+		     bsc->cfg->nr, con_bsc->cfg->nr);
+		goto exit2;
+	}
+
+	/* do not forward messages to the MSC */
+	if (con_filter)
+		goto exit2;
+
+	if (!con_msc) {
+		LOGP(DNAT, LOGL_ERROR, "Not forwarding data bsc_nr: %d ipa: %d type: 0x%x\n",
+			bsc->cfg->nr,
+			parsed ? parsed->ipa_proto : -1,
+			parsed ? parsed->sccp_type : -1);
+		goto exit2;
+	}
+
+	/* send the non-filtered but maybe modified msg */
+	queue_for_msc(con_msc, msg);
+	if (parsed)
+		talloc_free(parsed);
+	return 0;
+
+exit:
+	/* if we filter out the reset send an ack to the BSC */
+	if (parsed->bssap == 0 && parsed->gsm_type == BSS_MAP_MSG_RESET) {
+		send_reset_ack(bsc);
+		send_reset_ack(bsc);
+	} else if (parsed->ipa_proto == IPAC_PROTO_IPACCESS) {
+		/* do we know who is handling this? */
+		if (msg->l2h[0] == IPAC_MSGT_ID_RESP && msgb_l2len(msg) > 2) {
+			struct tlv_parsed tvp;
+			int ret;
+			ret = ipa_ccm_idtag_parse_off(&tvp,
+					     (unsigned char *) msg->l2h + 2,
+					     msgb_l2len(msg) - 2, 0);
+			if (ret < 0) {
+				LOGP(DNAT, LOGL_ERROR, "ignoring IPA response "
+					"message with malformed TLVs\n");
+				return ret;
+			}
+			if (TLVP_PRESENT(&tvp, IPAC_IDTAG_UNITNAME))
+				ipaccess_auth_bsc(&tvp, bsc);
+		}
+
+		goto exit2;
+	}
+
+exit2:
+	if (imsi)
+		talloc_free(imsi);
+	talloc_free(parsed);
+	msgb_free(msg);
+	return -1;
+
+exit3:
+	/* send a SCCP Connection Refused */
+	if (imsi)
+		talloc_free(imsi);
+	bsc_send_con_refuse(bsc, parsed, con_type, &cause);
+	talloc_free(parsed);
+	msgb_free(msg);
+	return -1;
+}
+
+static int ipaccess_bsc_read_cb(struct osmo_fd *bfd)
+{
+	struct bsc_connection *bsc = bfd->data;
+	struct msgb *msg = NULL;
+	struct ipaccess_head *hh;
+	struct ipaccess_head_ext *hh_ext;
+	int ret;
+
+	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &bsc->pending_msg);
+	if (ret <= 0) {
+		if (ret == -EAGAIN)
+			return 0;
+		if (ret == 0)
+			LOGP(DNAT, LOGL_ERROR,
+			     "The connection to the BSC Nr: %d was lost. Cleaning it\n",
+			     bsc->cfg ? bsc->cfg->nr : -1);
+		else
+			LOGP(DNAT, LOGL_ERROR,
+			     "Stream error on BSC Nr: %d. Failed to parse ip access message: %d (%s)\n",
+			     bsc->cfg ? bsc->cfg->nr : -1, ret, strerror(-ret));
+
+		bsc_close_connection(bsc);
+		return -1;
+	}
+
+
+	LOGP(DNAT, LOGL_DEBUG, "MSG from BSC: %s proto: %d\n", osmo_hexdump(msg->data, msg->len), msg->l2h[0]);
+
+	/* Handle messages from the BSC */
+	hh = (struct ipaccess_head *) msg->data;
+
+	/* stop the pong timeout */
+	if (hh->proto == IPAC_PROTO_IPACCESS) {
+		if (msg->l2h[0] == IPAC_MSGT_PONG) {
+			osmo_timer_del(&bsc->pong_timeout);
+			msgb_free(msg);
+			return 0;
+		} else if (msg->l2h[0] == IPAC_MSGT_PING) {
+			send_pong(bsc);
+			msgb_free(msg);
+			return 0;
+		}
+	/* Message contains the ipaccess_head_ext header, investigate further */
+	} else if (hh->proto == IPAC_PROTO_OSMO &&
+		   msg->len > sizeof(*hh) + sizeof(*hh_ext)) {
+
+		hh_ext = (struct ipaccess_head_ext *) hh->data;
+		/* l2h is where the actual command data is expected */
+		msg->l2h = hh_ext->data;
+
+		if (hh_ext->proto == IPAC_PROTO_EXT_CTRL)
+			return bsc_nat_handle_ctrlif_msg(bsc, msg);
+	}
+
+	/* FIXME: Currently no PONG is sent to the BSC */
+	/* FIXME: Currently no ID ACK is sent to the BSC */
+	forward_sccp_to_msc(bsc, msg);
+
+	return 0;
+}
+
+static int ipaccess_listen_bsc_cb(struct osmo_fd *bfd, unsigned int what)
+{
+	struct bsc_connection *bsc;
+	int fd, rc, on;
+	struct sockaddr_in sa;
+	socklen_t sa_len = sizeof(sa);
+
+	if (!(what & BSC_FD_READ))
+		return 0;
+
+	fd = accept(bfd->fd, (struct sockaddr *) &sa, &sa_len);
+	if (fd < 0) {
+		perror("accept");
+		return fd;
+	}
+
+	/* count the reconnect */
+	osmo_counter_inc(nat->stats.bsc.reconn);
+
+	/*
+	 * if we are not connected to a msc... just close the socket
+	 */
+	if (!bsc_nat_msc_is_connected(nat)) {
+		LOGP(DNAT, LOGL_NOTICE, "Disconnecting BSC due lack of MSC connection.\n");
+		close(fd);
+		return 0;
+	}
+
+	if (nat->blocked) {
+		LOGP(DNAT, LOGL_NOTICE, "Disconnecting BSC due NAT being blocked.\n");
+		close(fd);
+		return 0;
+	}
+
+	on = 1;
+	rc = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
+	if (rc != 0)
+                LOGP(DNAT, LOGL_ERROR, "Failed to set TCP_NODELAY: %s\n", strerror(errno));
+
+	rc = setsockopt(fd, IPPROTO_IP, IP_TOS,
+			&nat->bsc_ip_dscp, sizeof(nat->bsc_ip_dscp));
+	if (rc != 0)
+		LOGP(DNAT, LOGL_ERROR, "Failed to set IP_TOS: %s\n", strerror(errno));
+
+	/* todo... do something with the connection */
+	/* todo... use GNUtls to see if we want to trust this as a BTS */
+
+	/*
+	 *
+	 */
+	bsc = bsc_connection_alloc(nat);
+	if (!bsc) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate BSC struct.\n");
+		close(fd);
+		return -1;
+	}
+
+	bsc->write_queue.bfd.data = bsc;
+	bsc->write_queue.bfd.fd = fd;
+	bsc->write_queue.read_cb = ipaccess_bsc_read_cb;
+	bsc->write_queue.write_cb = bsc_write_cb;
+	bsc->write_queue.bfd.when = BSC_FD_READ;
+	if (osmo_fd_register(&bsc->write_queue.bfd) < 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to register BSC fd.\n");
+		close(fd);
+		talloc_free(bsc);
+		return -2;
+	}
+
+	LOGP(DNAT, LOGL_NOTICE, "BSC connection on %d with IP: %s\n",
+		fd, inet_ntoa(sa.sin_addr));
+
+	llist_add(&bsc->list_entry, &nat->bsc_connections);
+	bsc->last_id = 0;
+
+	send_id_ack(bsc);
+	send_id_req(nat, bsc);
+	send_mgcp_reset(bsc);
+
+	/*
+	 * start the hangup timer
+	 */
+	osmo_timer_setup(&bsc->id_timeout, ipaccess_close_bsc, bsc);
+	osmo_timer_schedule(&bsc->id_timeout, nat->auth_timeout, 0);
+	return 0;
+}
+
+static void print_usage()
+{
+	printf("Usage: bsc_nat\n");
+}
+
+static void print_help()
+{
+	printf("  Some useful help...\n");
+	printf("  -h --help this text\n");
+	printf("  -d option --debug=DRLL:DCC:DMM:DRR:DRSL:DNM enable debugging\n");
+	printf("  -D --daemonize Fork the process into a background daemon\n");
+	printf("  -s --disable-color\n");
+	printf("  -c --config-file filename The config file to use.\n");
+	printf("  -m --msc=IP. The address of the MSC.\n");
+	printf("  -l --local=IP. The local address of this BSC.\n");
+}
+
+static void handle_options(int argc, char **argv)
+{
+	while (1) {
+		int option_index = 0, c;
+		static struct option long_options[] = {
+			{"help", 0, 0, 'h'},
+			{"debug", 1, 0, 'd'},
+			{"daemonize", 0, 0, 'D'},
+			{"config-file", 1, 0, 'c'},
+			{"disable-color", 0, 0, 's'},
+			{"timestamp", 0, 0, 'T'},
+			{"msc", 1, 0, 'm'},
+			{"local", 1, 0, 'l'},
+			{0, 0, 0, 0}
+		};
+
+		c = getopt_long(argc, argv, "hd:sTPc:m:l:D",
+				long_options, &option_index);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'h':
+			print_usage();
+			print_help();
+			exit(0);
+		case 's':
+			log_set_use_color(osmo_stderr_target, 0);
+			break;
+		case 'd':
+			log_parse_category_mask(osmo_stderr_target, optarg);
+			break;
+		case 'D':
+			daemonize = 1;
+			break;
+		case 'c':
+			config_file = optarg;
+			break;
+		case 'T':
+			log_set_print_timestamp(osmo_stderr_target, 1);
+			break;
+		case 'm':
+			msc_ip = optarg;
+			break;
+		case 'l':
+			inet_aton(optarg, &local_addr);
+			break;
+		default:
+			/* ignore */
+			break;
+		}
+	}
+}
+
+static void signal_handler(int signal)
+{
+	switch (signal) {
+	case SIGABRT:
+		/* in case of abort, we want to obtain a talloc report
+		 * and then return to the caller, who will abort the process */
+	case SIGUSR1:
+		talloc_report_full(tall_bsc_ctx, stderr);
+		break;
+	default:
+		break;
+	}
+}
+
+static void sccp_close_unconfirmed(void *_data)
+{
+	int destroyed = 0;
+	struct bsc_connection *bsc, *bsc_tmp;
+	struct nat_sccp_connection *conn, *tmp1;
+	struct timespec now;
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	llist_for_each_entry_safe(conn, tmp1, &nat->sccp_connections, list_entry) {
+		if (conn->has_remote_ref)
+			continue;
+
+		int diff = (now.tv_sec - conn->creation_time.tv_sec) / 60;
+		if (diff < SCCP_CLOSE_TIME_TIMEOUT)
+			continue;
+
+		LOGP(DNAT, LOGL_ERROR,
+			"SCCP connection 0x%x/0x%x was never confirmed on bsc nr. %d\n",
+			sccp_src_ref_to_int(&conn->real_ref),
+			sccp_src_ref_to_int(&conn->patched_ref),
+			conn->bsc->cfg->nr);
+		sccp_connection_destroy(conn);
+		destroyed = 1;
+	}
+
+	if (!destroyed)
+		goto out;
+
+	/* now close out any BSC */
+	llist_for_each_entry_safe(bsc, bsc_tmp, &nat->bsc_connections, list_entry)
+		bsc_maybe_close(bsc);
+
+out:
+	osmo_timer_schedule(&sccp_close, SCCP_CLOSE_TIME, 0);
+}
+
+extern void *tall_ctr_ctx;
+static void talloc_init_ctx()
+{
+	tall_bsc_ctx = talloc_named_const(NULL, 0, "nat");
+	msgb_talloc_ctx_init(tall_bsc_ctx, 0);
+	tall_ctr_ctx = talloc_named_const(tall_bsc_ctx, 0, "counter");
+}
+
+extern int bsc_vty_go_parent(struct vty *vty);
+
+static struct vty_app_info vty_info = {
+	.name 		= "OsmoBSCNAT",
+	.version	= PACKAGE_VERSION,
+	.go_parent_cb	= bsc_vty_go_parent,
+	.is_config_node	= bsc_vty_is_config_node,
+};
+
+
+int main(int argc, char **argv)
+{
+	int rc;
+
+	talloc_init_ctx();
+
+	osmo_init_logging(&log_info);
+
+	nat = bsc_nat_alloc();
+	if (!nat) {
+		fprintf(stderr, "Failed to allocate the BSC nat.\n");
+		return -4;
+	}
+
+	nat->mgcp_cfg = mgcp_config_alloc();
+	if (!nat->mgcp_cfg) {
+		fprintf(stderr, "Failed to allocate MGCP cfg.\n");
+		return -5;
+	}
+
+	/* We need to add mode-set for amr codecs */
+	nat->sdp_ensure_amr_mode_set = 1;
+
+	vty_info.copyright = openbsc_copyright;
+	vty_init(&vty_info);
+	logging_vty_add_cmds(NULL);
+	osmo_stats_vty_add_cmds(&log_info);
+	bsc_nat_vty_init(nat);
+	ctrl_vty_init(tall_bsc_ctx);
+
+
+	/* parse options */
+	local_addr.s_addr = INADDR_ANY;
+	handle_options(argc, argv);
+
+	nat->include_base = dirname(talloc_strdup(tall_bsc_ctx, config_file));
+
+	rate_ctr_init(tall_bsc_ctx);
+	osmo_stats_init(tall_bsc_ctx);
+
+	/* init vty and parse */
+	if (mgcp_parse_config(config_file, nat->mgcp_cfg, MGCP_BSC_NAT) < 0) {
+		fprintf(stderr, "Failed to parse the config file: '%s'\n", config_file);
+		return -3;
+	}
+
+	/* start telnet after reading config for vty_get_bind_addr() */
+	if (telnet_init_dynif(tall_bsc_ctx, NULL, vty_get_bind_addr(),
+			      OSMO_VTY_PORT_BSC_NAT)) {
+		fprintf(stderr, "Creating VTY telnet line failed\n");
+		return -5;
+	}
+
+	/* over rule the VTY config for MSC IP */
+	if (msc_ip)
+		bsc_nat_set_msc_ip(nat, msc_ip);
+
+	/* seed the PRNG */
+	srand(time(NULL));
+
+	LOGP(DNAT, LOGL_NOTICE, "BSCs configured from %s\n", nat->resolved_path);
+
+	/*
+	 * Setup the MGCP code..
+	 */
+	if (bsc_mgcp_nat_init(nat) != 0)
+		return -4;
+
+	/* connect to the MSC */
+	nat->msc_con = bsc_msc_create(nat, &nat->dests);
+	if (!nat->msc_con) {
+		fprintf(stderr, "Creating a bsc_msc_connection failed.\n");
+		exit(1);
+	}
+
+	/* start control interface after reading config for
+	 * ctrl_vty_get_bind_addr() */
+	nat->ctrl = bsc_nat_controlif_setup(nat, ctrl_vty_get_bind_addr(),
+					    OSMO_CTRL_PORT_BSC_NAT);
+	if (!nat->ctrl) {
+		fprintf(stderr, "Creating the control interface failed.\n");
+		exit(1);
+	}
+
+	nat->msc_con->name = "main MSC";
+	nat->msc_con->connection_loss = msc_connection_was_lost;
+	nat->msc_con->connected = msc_connection_connected;
+	nat->msc_con->write_queue.read_cb = ipaccess_msc_read_cb;
+	nat->msc_con->write_queue.write_cb = ipaccess_msc_write_cb;;
+	nat->msc_con->write_queue.bfd.data = nat->msc_con;
+	bsc_msc_connect(nat->msc_con);
+
+	/* wait for the BSC */
+	rc = make_sock(&bsc_listen, IPPROTO_TCP, ntohl(local_addr.s_addr),
+		       5000, 0, ipaccess_listen_bsc_cb, nat);
+	if (rc != 0) {
+		fprintf(stderr, "Failed to listen for BSC.\n");
+		exit(1);
+	}
+
+	rc = bsc_ussd_init(nat);
+	if (rc != 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to bind the USSD socket.\n");
+		exit(1);
+	}
+
+	signal(SIGABRT, &signal_handler);
+	signal(SIGUSR1, &signal_handler);
+	osmo_init_ignore_signals();
+
+	if (daemonize) {
+		rc = osmo_daemonize();
+		if (rc < 0) {
+			perror("Error during daemonize");
+			exit(1);
+		}
+	}
+
+	/* recycle timer */
+	sccp_set_log_area(DSCCP);
+	osmo_timer_setup(&sccp_close, sccp_close_unconfirmed, NULL);
+	osmo_timer_schedule(&sccp_close, SCCP_CLOSE_TIME, 0);
+
+	while (1) {
+		osmo_select_main(0);
+	}
+
+	return 0;
+}
+
+/* Close all connections handed out to the USSD module */
+int bsc_ussd_close_connections(struct bsc_nat *nat)
+{
+	struct nat_sccp_connection *con;
+	llist_for_each_entry(con, &nat->sccp_connections, list_entry) {
+		if (con->con_local != NAT_CON_END_USSD)
+			continue;
+		if (!con->bsc)
+			continue;
+
+		nat_send_clrc_bsc(con);
+		nat_send_rlsd_bsc(con);
+	}
+
+	return 0;
+}