diff --git a/openbsc/src/Makefile.am b/openbsc/src/Makefile.am
index 891a112..7912008 100644
--- a/openbsc/src/Makefile.am
+++ b/openbsc/src/Makefile.am
@@ -2,7 +2,7 @@
 AM_CFLAGS=-Wall
 
 sbin_PROGRAMS = bsc_hack bs11_config ipaccess-find ipaccess-config isdnsync
-noinst_LIBRARIES = libbsc.a libmsc.a libvty.a
+noinst_LIBRARIES = libbsc.a libmsc.a libvty.a libsccp.a
 noinst_HEADERS = vty/cardshell.h
 
 libbsc_a_SOURCES = abis_rsl.c abis_nm.c gsm_data.c gsm_04_08_utils.c \
@@ -18,6 +18,8 @@
 
 libvty_a_SOURCES = vty/buffer.c vty/command.c vty/vector.c vty/vty.c
 
+libsccp_a_SOURCES = sccp/sccp.c
+
 bsc_hack_SOURCES = bsc_hack.c bsc_init.c vty_interface.c vty_interface_layer3.c
 bsc_hack_LDADD = libmsc.a libbsc.a libmsc.a libvty.a -ldl -ldbi $(LIBCRYPT)
 
diff --git a/openbsc/src/sccp/sccp.c b/openbsc/src/sccp/sccp.c
new file mode 100644
index 0000000..8b111b2
--- /dev/null
+++ b/openbsc/src/sccp/sccp.c
@@ -0,0 +1,1129 @@
+/*
+ * SCCP management code
+ *
+ * (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2009 by on-waves.com
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <string.h>
+
+#include <sccp/sccp.h>
+
+#include <openbsc/debug.h>
+#include <openbsc/talloc.h>
+#include <openbsc/linuxlist.h>
+
+static void *tall_sccp_ctx;
+static LLIST_HEAD(sccp_connections);
+
+#define SCCP_MSG_SIZE 4096
+#define SCCP_MSG_HEADROOM 128
+
+/* global data */
+const struct sockaddr_sccp sccp_ssn_bssap = {
+	.sccp_family	= 0,
+	.sccp_ssn	= SCCP_SSN_BSSAP,
+};
+
+struct sccp_system {
+	/* layer3 -> layer2 */
+	int (*write_data)(struct msgb *data, void *context);
+	void *write_context;
+};
+
+
+static struct sccp_system sccp_system = {
+	.write_data = NULL,
+};
+
+struct sccp_data_callback {
+	/* connection based */
+	int (*accept_cb)(struct sccp_connection *, void *);
+	void *accept_context;
+
+	/* connection less */
+	int (*read_cb)(struct msgb *, unsigned int, void *);
+	void *read_context;
+
+	u_int8_t ssn;
+	struct llist_head callback;
+};
+
+static LLIST_HEAD(sccp_callbacks);
+
+static struct sccp_data_callback *_find_ssn(u_int8_t ssn)
+{
+	struct sccp_data_callback *cb;
+
+	llist_for_each_entry(cb, &sccp_callbacks, callback) {
+		if (cb->ssn == ssn)
+			return cb;
+	}
+
+	/* need to add one */
+	cb = talloc_zero(tall_sccp_ctx, struct sccp_data_callback);
+	if (!cb) {
+		DEBUGP(DSCCP, "Failed to allocate sccp callback.\n");
+		return NULL;
+	}
+
+	cb->ssn = ssn;
+	llist_add_tail(&cb->callback, &sccp_callbacks);
+	return cb;
+}
+
+
+static int _send_msg(struct msgb *msg)
+{
+	return sccp_system.write_data(msg, sccp_system.write_context);
+}
+
+/*
+ * parsing routines
+ */
+static int copy_address(struct sccp_address *addr, u_int8_t offset, struct msgb *msgb)
+{
+	struct sccp_called_party_address *party;
+
+	int room = msgb_l2len(msgb) - offset;
+	u_int8_t read = 0;
+	u_int8_t length;
+
+	if (room <= 0) {
+		DEBUGP(DSCCP, "Not enough room for an address: %u\n", room);
+		return -1;
+	}
+
+	length = msgb->l2h[offset];
+	if (room <= length) {
+		DEBUGP(DSCCP, "Not enough room for optional data %u %u\n", room, length);
+		return -1;
+	}
+
+
+	party = (struct sccp_called_party_address *)(msgb->l2h + offset + 1);
+	if (party->point_code_indicator) {
+		if (length <= read + 2) {
+		    DEBUGP(DSCCP, "POI does not fit %u\n", length);
+		    return -1;
+		}
+
+
+		memcpy(&addr->poi, &party->data[read], 2);
+		read += 2;
+	}
+
+	if (party->ssn_indicator) {
+		if (length <= read + 1) {
+		    DEBUGP(DSCCP, "SSN does not fit %u\n", length);
+		    return -1;
+		}
+
+		addr->ssn = party->data[read];
+		read += 1;
+	}
+
+	if (party->global_title_indicator) {
+		DEBUGP(DSCCP, "GTI not supported %u\n", *(u_int8_t *)party);
+		return -1;
+	}
+
+	addr->address = *party;
+	return 0;
+}
+
+static int check_address(struct sccp_address *addr)
+{
+	/* ignore point_code_indicator... it should be zero... but */
+	if (addr->address.ssn_indicator != 1
+	    || addr->address.global_title_indicator == 1
+	    || addr->address.routing_indicator != 1) {
+		DEBUGP(DSCCP, "Invalid called address according to 08.06: 0x%x 0x%x\n",
+			*(u_int8_t *)&addr->address, addr->ssn);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int _sccp_parse_optional_data(const int offset,
+				     struct msgb *msgb, struct sccp_optional_data *data)
+{
+	u_int16_t room = msgb_l2len(msgb) - offset;
+	u_int16_t read = 0;
+
+	while (room > read) {
+		u_int8_t type = msgb->l2h[offset + read];
+		if (type == SCCP_PNC_END_OF_OPTIONAL)
+			return 0;
+
+		if (read + 1 >= room) {
+			DEBUGP(DSCCP, "no place for length\n");
+			return 0;
+		}
+
+		u_int8_t length = msgb->l2h[offset + read + 1];
+		read += 2 + length;
+
+
+		if (room <= read) {
+			DEBUGP(DSCCP, "no space for the data: type: %d read: %d room: %d l2: %d\n",
+			       type, read, room, msgb_l2len(msgb));
+			return 0;
+		}
+
+		if (type == SCCP_PNC_DATA) {
+			data->data_len = length;
+			data->data_start = offset + read - length;
+		}
+
+	}
+
+	return -1;
+}
+
+/*
+ * Send UDT. Currently we have a fixed address...
+ */
+static int _sccp_send_data(int class, const struct sockaddr_sccp *in,
+			   const struct sockaddr_sccp *out, struct msgb *payload)
+{
+	struct sccp_data_unitdata *udt;
+	u_int8_t *data;
+	int ret;
+
+	if (msgb_l3len(payload) > 256) {
+		DEBUGP(DSCCP, "The payload is too big for one udt\n");
+		return -1;
+	}
+
+	struct msgb *msg = msgb_alloc_headroom(SCCP_MSG_SIZE,
+					       SCCP_MSG_HEADROOM, "sccp: udt");
+	msg->l2h = &msg->data[0];
+	udt = (struct sccp_data_unitdata *)msgb_put(msg, sizeof(*udt));
+
+	udt->type = SCCP_MSG_TYPE_UDT;
+	udt->proto_class = class;
+	udt->variable_called = 3;
+	udt->variable_calling = 5;
+	udt->variable_data = 7;
+
+	/* for variable data we start with a size and the data */
+	data = msgb_put(msg, 1 + 2);
+	data[0] = 2;
+	data[1] = 0x42;
+	data[2] = out->sccp_ssn;
+
+	data = msgb_put(msg, 1 + 2);
+	data[0] = 2;
+	data[1] = 0x42;
+	data[2] = in->sccp_ssn;
+
+	/* copy the payload */
+	data = msgb_put(msg, 1 + msgb_l3len(payload));
+	data[0] = msgb_l3len(payload);
+	memcpy(&data[1], payload->l3h, msgb_l3len(payload));
+
+	ret = _send_msg(msg);
+	msgb_free(msg);
+
+	return ret;
+}
+
+static int _sccp_handle_read(struct msgb *msgb)
+{
+	static const u_int32_t header_size = sizeof(struct sccp_data_unitdata);
+	static const u_int32_t called_offset = offsetof(struct sccp_data_unitdata, variable_called);
+	static const u_int32_t calling_offset = offsetof(struct sccp_data_unitdata, variable_calling);
+	static const u_int32_t data_offset = offsetof(struct sccp_data_unitdata, variable_data);
+
+	struct sccp_data_callback *cb;
+	struct sccp_data_unitdata *udt = (struct sccp_data_unitdata *)msgb->l2h;
+	struct sccp_address called, calling;
+
+	/* we don't have enough size for the struct */
+	if (msgb_l2len(msgb) < header_size) {
+		DEBUGP(DSCCP, "msgb < header_size %u %u\n",
+		        msgb_l2len(msgb), header_size);
+		return -1;
+	}
+
+	/* copy out the calling and called address. Add the off */
+	if (copy_address(&called, called_offset + udt->variable_called, msgb) != 0)
+		return -1;
+
+	if (check_address(&called) != 0) {
+		DEBUGP(DSCCP, "Invalid called address according to 08.06: 0x%x 0x%x\n",
+			*(u_int8_t *)&called.address, called.ssn);
+		return -1;
+	}
+
+	cb = _find_ssn(called.ssn);
+	if (!cb || !cb->read_cb) {
+		DEBUGP(DSCCP, "No routing for UDT for called SSN: %u\n", called.ssn);
+		return -1;
+	}
+
+	if (copy_address(&calling, calling_offset + udt->variable_calling, msgb) != 0)
+		return -1;
+
+	if (check_address(&calling) != 0) {
+		DEBUGP(DSCCP, "Invalid called address according to 08.06: 0x%x 0x%x\n",
+			*(u_int8_t *)&called.address, called.ssn);
+	}
+
+	/* we don't have enough size for the data */
+	if (msgb_l2len(msgb) < data_offset + udt->variable_data + 1) {
+		DEBUGP(DSCCP, "msgb < header + offset %u %u %u\n",
+			msgb_l2len(msgb), header_size, udt->variable_data);
+		return -1;
+	}
+
+
+	msgb->l3h = &udt->data[udt->variable_data];
+
+	if (msgb_l3len(msgb) !=  msgb->l3h[-1]) {
+		DEBUGP(DSCCP, "msgb is truncated %u %u\n",
+			msgb_l3len(msgb), msgb->l3h[-1]);
+		return -1;
+	}
+
+	/* sanity check */
+	return cb->read_cb(msgb, msgb_l3len(msgb), cb->read_context);
+}
+
+/*
+ * handle connection orientated methods
+ */
+static int source_local_reference_is_free(struct sccp_source_reference *reference)
+{
+	struct sccp_connection *connection;
+
+	llist_for_each_entry(connection, &sccp_connections, list) {
+		if (memcmp(reference, &connection->source_local_reference, sizeof(*reference)) == 0)
+			return -1;
+	}
+
+	return 0;
+}
+
+static int destination_local_reference_is_free(struct sccp_source_reference *reference)
+{
+	struct sccp_connection *connection;
+
+	llist_for_each_entry(connection, &sccp_connections, list) {
+		if (memcmp(reference, &connection->destination_local_reference, sizeof(*reference)) == 0)
+			return -1;
+	}
+
+	return 0;
+}
+
+static int assign_source_local_reference(struct sccp_connection *connection)
+{
+	static u_int32_t last_ref = 0x30000;
+	int wrapped = 0;
+
+	do {
+		struct sccp_source_reference reference;
+		reference.octet1 = (last_ref >>  0) & 0xff;
+		reference.octet2 = (last_ref >>  8) & 0xff;
+		reference.octet3 = (last_ref >> 16) & 0xff;
+
+		++last_ref;
+		/* do not use the reversed word and wrap around */
+		if ((last_ref & 0x00FFFFFF) == 0x00FFFFFF) {
+			DEBUGP(DSCCP, "Wrapped searching for a free code\n");
+			last_ref = 0;
+			++wrapped;
+		}
+
+		if (source_local_reference_is_free(&reference) == 0) {
+			connection->source_local_reference = reference;
+			return 0;
+		}
+	} while (wrapped != 2);
+
+	DEBUGP(DSCCP, "Finding a free reference failed\n");
+	return -1;
+}
+
+static void _sccp_set_connection_state(struct sccp_connection *connection, int new_state)
+{
+	int old_state = connection->connection_state;
+
+	connection->connection_state = new_state;
+	if (connection->state_cb)
+		connection->state_cb(connection, old_state);
+}
+
+static int _sccp_send_refuse(struct sccp_connection_request *req, int cause)
+{
+	struct msgb *msgb;
+	struct sccp_connection_refused *ref;
+	u_int8_t *data;
+	int ret;
+
+	msgb = msgb_alloc_headroom(SCCP_MSG_SIZE,
+				   SCCP_MSG_HEADROOM, "sccp ref");
+	msgb->l2h = &msgb->data[0];
+
+	ref = (struct sccp_connection_refused *) msgb_put(msgb, sizeof(*ref));
+	ref->type = SCCP_MSG_TYPE_CREF;
+	memcpy(&ref->destination_local_reference, &req->source_local_reference,
+	       sizeof(struct sccp_source_reference));
+	ref->cause = cause;
+	ref->optional_start = 1;
+
+	data = msgb_put(msgb, 1);
+	data[0] = SCCP_PNC_END_OF_OPTIONAL;
+
+	ret = _send_msg(msgb);
+	msgb_free(msgb);
+	return ret;
+}
+
+static int _sccp_send_connection_confirm(struct sccp_connection *connection)
+{
+	struct msgb *response;
+	struct sccp_connection_confirm *confirm;
+	u_int8_t *optional_data;
+	int ret;
+
+	if (assign_source_local_reference(connection) != 0)
+		return -1;
+
+	response = msgb_alloc_headroom(SCCP_MSG_SIZE,
+				       SCCP_MSG_HEADROOM, "sccp confirm");
+	response->l2h = &response->data[0];
+
+	confirm = (struct sccp_connection_confirm *) msgb_put(response, sizeof(*confirm));
+
+	confirm->type = SCCP_MSG_TYPE_CC;
+	memcpy(&confirm->destination_local_reference,
+	       &connection->destination_local_reference,
+	       sizeof(connection->destination_local_reference));
+	memcpy(&confirm->source_local_reference,
+	       &connection->source_local_reference,
+	       sizeof(connection->source_local_reference));
+	confirm->proto_class = 2;
+	confirm->optional_start = 1;
+
+	optional_data = (u_int8_t *) msgb_put(response, 1);
+	optional_data[0] = SCCP_PNC_END_OF_OPTIONAL;
+
+	ret = _send_msg(response);
+	msgb_free(response);
+
+	_sccp_set_connection_state(connection, SCCP_CONNECTION_STATE_ESTABLISHED);
+	return ret;
+}
+
+static int _sccp_send_connection_request(struct sccp_connection *connection,
+					 const struct sockaddr_sccp *called, struct msgb *msg)
+{
+	struct msgb *request;
+	struct sccp_connection_request *req;
+	u_int8_t *data;
+	u_int8_t extra_size = 3 + 1;
+	int ret;
+
+
+	if (msg && (msgb_l3len(msg) < 3 || msgb_l3len(msg) > 130)) {
+		DEBUGP(DSCCP, "Invalid amount of data... %d\n", msgb_l3len(msg));
+		return -1;
+	}
+
+	/* try to find a id */
+	if (assign_source_local_reference(connection) != 0) {
+		DEBUGP(DSCCP, "Assigning a local reference failed.\n");
+		_sccp_set_connection_state(connection, SCCP_CONNECTION_STATE_SETUP_ERROR);
+		return -1;
+	}
+
+
+	if (msg)
+		extra_size += 2 + msgb_l3len(msg);
+	request = msgb_alloc_headroom(SCCP_MSG_SIZE,
+				      SCCP_MSG_HEADROOM, "sccp connection request");
+	request->l2h = &request->data[0];
+	req = (struct sccp_connection_request *) msgb_put(request, sizeof(*req));
+
+	req->type = SCCP_MSG_TYPE_CR;
+	memcpy(&req->source_local_reference, &connection->source_local_reference,
+	       sizeof(connection->source_local_reference));
+	req->proto_class = 2;
+	req->variable_called = 2;
+	req->optional_start = 4;
+
+	/* write the called party address */
+	data = msgb_put(request, 1 + 2);
+	data[0] = 2;
+	data[1] = 0x42;
+	data[2] = called->sccp_ssn;
+
+	/* write the payload */
+	if (msg) {
+	    data = msgb_put(request, 2 + msgb_l3len(msg));
+	    data[0] = SCCP_PNC_DATA;
+	    data[1] = msgb_l3len(msg);
+	    memcpy(&data[2], msg->l3h, msgb_l3len(msg));
+	}
+
+	data = msgb_put(request, 1);
+	data[0] = SCCP_PNC_END_OF_OPTIONAL;
+
+	llist_add_tail(&connection->list, &sccp_connections);
+	_sccp_set_connection_state(connection, SCCP_CONNECTION_STATE_REQUEST);
+
+	ret = _send_msg(request);
+	msgb_free(request);
+
+	return ret;
+}
+
+static int _sccp_send_connection_data(struct sccp_connection *conn, struct msgb *_data)
+{
+	struct msgb *msgb;
+	struct sccp_data_form1 *dt1;
+	u_int8_t *data;
+	int extra_size;
+	int ret;
+
+	if (msgb_l3len(_data) < 2 || msgb_l3len(_data) > 256) {
+		DEBUGP(DSCCP, "data size too big, segmenting unimplemented.\n");
+		return -1;
+	}
+
+	extra_size = 1 + msgb_l3len(_data);
+	msgb = msgb_alloc_headroom(SCCP_MSG_SIZE,
+				   SCCP_MSG_HEADROOM, "sccp dt1");
+	msgb->l2h = &msgb->data[0];
+
+	dt1 = (struct sccp_data_form1 *) msgb_put(msgb, sizeof(*dt1));
+	dt1->type = SCCP_MSG_TYPE_DT1;
+	memcpy(&dt1->destination_local_reference, &conn->destination_local_reference,
+	       sizeof(struct sccp_source_reference));
+	dt1->segmenting = 0;
+
+	/* copy the data */
+	dt1->variable_start = 1;
+	data = msgb_put(msgb, extra_size);
+	data[0] = extra_size - 1;
+	memcpy(&data[1], _data->l3h, extra_size - 1);
+
+	ret = _send_msg(msgb);
+	msgb_free(msgb);
+
+	return ret;
+}
+
+static int _sccp_send_connection_released(struct sccp_connection *conn, int cause)
+{
+	struct msgb *msg;
+	struct sccp_connection_released *rel;
+	u_int8_t *data;
+	int ret;
+
+	msg = msgb_alloc_headroom(SCCP_MSG_SIZE, SCCP_MSG_HEADROOM,
+				  "sccp: connection released");
+	msg->l2h = &msg->data[0];
+	rel = (struct sccp_connection_released *) msgb_put(msg, sizeof(*rel));
+	rel->type = SCCP_MSG_TYPE_RLSD;
+	rel->release_cause = cause;
+
+	/* copy the source references */
+	memcpy(&rel->destination_local_reference, &conn->destination_local_reference,
+	       sizeof(struct sccp_source_reference));
+	memcpy(&rel->source_local_reference, &conn->source_local_reference,
+	       sizeof(struct sccp_source_reference));
+
+	data = msgb_put(msg, 1);
+	data[0] = SCCP_PNC_END_OF_OPTIONAL;
+
+	_sccp_set_connection_state(conn, SCCP_CONNECTION_STATE_RELEASE);
+	ret = _send_msg(msg);
+	msgb_free(msg);
+
+	return ret;
+}
+
+/*
+ * Open a connection. The following is going to happen:
+ *
+ *	- Verify the packet, e.g. that we have no other connection
+ *	  that id.
+ *      - Ask the user if he wants to accept the connection
+ *      - Try to open the connection by assigning a source local reference
+ *        and sending the packet
+ */
+static int _sccp_handle_connection_request(struct msgb *msgb)
+{
+	static const u_int32_t header_size =
+			sizeof(struct sccp_connection_request);
+	static const u_int32_t optional_offset =
+			offsetof(struct sccp_connection_request, optional_start);
+	static const u_int32_t called_offset =
+			offsetof(struct sccp_connection_request, variable_called);
+
+	struct sccp_data_callback *cb;
+	struct sccp_connection_request *req = (struct sccp_connection_request *)msgb->data;
+	struct sccp_address called;
+	struct sccp_connection *connection;
+	struct sccp_optional_data optional_data;
+
+	/* header check */
+	if (msgb_l2len(msgb) < header_size) {
+		DEBUGP(DSCCP, "msgb < header_size %u %u\n",
+		        msgb_l2len(msgb), header_size);
+		return -1;
+	}
+
+	/* copy out the calling and called address. Add the offset */
+	if (copy_address(&called, called_offset + req->variable_called, msgb) != 0)
+		return -1;
+
+	if (check_address(&called) != 0) {
+		DEBUGP(DSCCP, "Invalid called address according to 08.06: 0x%x 0x%x\n",
+			*(u_int8_t *)&called.address, called.ssn);
+		return -1;
+	}
+
+	cb = _find_ssn(called.ssn);
+	if (!cb || !cb->accept_cb) {
+		DEBUGP(DSCCP, "No routing for CR for called SSN: %u\n", called.ssn);
+		return -1;
+	}
+
+	/* check if the system wants this connection */
+	connection = talloc_zero(tall_sccp_ctx, struct sccp_connection);
+	if (!connection) {
+		DEBUGP(DSCCP, "Allocation failed\n");
+		return -1;
+	}
+
+	/*
+	 * sanity checks:
+	 *	- Is the source_local_reference in any other connection?
+	 * then will call accept, assign a "destination" local reference
+	 * and send a connection confirm, otherwise we will send a refuseed
+	 * one....
+	 */
+	if (destination_local_reference_is_free(&req->source_local_reference) != 0) {
+		DEBUGP(DSCCP, "Need to reject connection with existing reference\n");
+		_sccp_send_refuse(req, SCCP_REFUSAL_SCCP_FAILURE);
+		talloc_free(connection);
+		return -1;
+	}
+
+	connection->incoming = 1;
+	connection->destination_local_reference = req->source_local_reference;
+
+	/*
+	 * parse optional data.
+	 */
+	memset(&optional_data, 0, sizeof(optional_data));
+	if (_sccp_parse_optional_data(optional_offset + req->optional_start, msgb, &optional_data) != 0) {
+		DEBUGP(DSCCP, "parsing of optional data failed.\n");
+		talloc_free(connection);
+		return -1;
+	}
+
+	if (cb->accept_cb(connection, cb->accept_context) != 0) {
+		_sccp_send_refuse(req, SCCP_REFUSAL_END_USER_ORIGINATED);
+		_sccp_set_connection_state(connection, SCCP_CONNECTION_STATE_REFUSED);
+		talloc_free(connection);
+		return 0;
+	}
+
+
+	llist_add_tail(&connection->list, &sccp_connections);
+
+	if (_sccp_send_connection_confirm(connection) != 0) {
+		DEBUGP(DSCCP, "Sending confirm failed... no available source reference?\n");
+
+		_sccp_send_refuse(req, SCCP_REFUSAL_SCCP_FAILURE);
+		_sccp_set_connection_state(connection, SCCP_CONNECTION_STATE_REFUSED);
+		llist_del(&connection->list);
+		talloc_free(connection);
+
+		return -1;
+	}
+
+	/*
+	 * If we have data let us forward things.
+	 */
+	if (optional_data.data_len != 0 && connection->data_cb) {
+		msgb->l3h = &msgb->l2h[optional_data.data_start];
+		connection->data_cb(connection, msgb, optional_data.data_len);
+	}
+
+	return 0;
+}
+
+/* Handle the release confirmed */
+static int _sccp_handle_connection_release_complete(struct msgb *data)
+{
+	static int header_size = sizeof(struct sccp_connection_release_complete);
+
+	struct sccp_connection_release_complete *cmpl;
+	struct sccp_connection *conn;
+
+	/* header check */
+	if (msgb_l2len(data) < header_size) {
+		DEBUGP(DSCCP, "msgb < header_size %u %u\n",
+		        msgb_l2len(data), header_size);
+		return -1;
+	}
+
+	cmpl = (struct sccp_connection_release_complete *) data->l2h;
+
+	/* find the connection */
+	llist_for_each_entry(conn, &sccp_connections, list) {
+		if (conn->data_cb
+		    && memcmp(&conn->source_local_reference,
+			      &cmpl->destination_local_reference,
+			      sizeof(conn->source_local_reference)) == 0
+		    && memcmp(&conn->destination_local_reference,
+			      &cmpl->source_local_reference,
+			      sizeof(conn->destination_local_reference)) == 0) {
+		    goto found;
+		}
+	}
+
+
+	DEBUGP(DSCCP, "Release complete of unknown connection\n");
+	return -1;
+
+found:
+	llist_del(&conn->list);
+	_sccp_set_connection_state(conn, SCCP_CONNECTION_STATE_RELEASE_COMPLETE);
+	return 0;
+}
+
+/* Handle the Data Form 1 message */
+static int _sccp_handle_connection_dt1(struct msgb *data)
+{
+	static int variable_offset = offsetof(struct sccp_data_form1, variable_start);
+	static int header_size = sizeof(struct sccp_data_form1);
+
+	struct sccp_data_form1 *dt1 = (struct sccp_data_form1 *)data->l2h;
+	struct sccp_connection *conn;
+	int size;
+
+	/* we don't have enough size for the struct */
+	if (msgb_l2len(data) < header_size) {
+		DEBUGP(DSCCP, "msgb > header_size %u %u\n",
+		        msgb_l2len(data), header_size);
+		return -1;
+	}
+
+	if (dt1->segmenting != 0) {
+		DEBUGP(DSCCP, "This packet has segmenting, not supported: %d\n", dt1->segmenting);
+		return -1;
+	}
+
+	/* lookup if we have a connection with the given reference */
+	llist_for_each_entry(conn, &sccp_connections, list) {
+		if (conn->data_cb
+		    && memcmp(&conn->source_local_reference,
+			      &dt1->destination_local_reference,
+			      sizeof(conn->source_local_reference)) == 0) {
+
+			/* some more  size checks in here */
+			if (msgb_l2len(data) < variable_offset + dt1->variable_start + 1) {
+				DEBUGP(DSCCP, "Not enough space for variable start: %u %u\n",
+					msgb_l2len(data), dt1->variable_start);
+				return -1;
+			}
+
+			size = data->l2h[variable_offset + dt1->variable_start];
+			data->l3h = &data->l2h[dt1->variable_start + variable_offset + 1];
+
+			if (msgb_l3len(data) < size) {
+				DEBUGP(DSCCP, "Not enough room for the payload: %u %u\n",
+					msgb_l3len(data), size);
+				return -1;
+			}
+
+			conn->data_cb(conn, data, size);
+			return 0;
+		}
+	}
+
+	DEBUGP(DSCCP, "No connection found for dt1 data\n");
+	return -1;
+}
+
+/* confirm a connection release */
+static int _sccp_send_connection_release_complete(struct sccp_connection *connection)
+{
+	struct msgb *msgb;
+	struct sccp_connection_release_complete *rlc;
+	int ret;
+
+	msgb = msgb_alloc_headroom(SCCP_MSG_SIZE,
+				   SCCP_MSG_HEADROOM, "sccp rlc");
+	msgb->l2h = &msgb->data[0];
+
+	rlc = (struct sccp_connection_release_complete *) msgb_put(msgb, sizeof(*rlc));
+	rlc->type = SCCP_MSG_TYPE_RLC;
+	memcpy(&rlc->destination_local_reference,
+	       &connection->destination_local_reference, sizeof(struct sccp_source_reference));
+	memcpy(&rlc->source_local_reference,
+	       &connection->source_local_reference, sizeof(struct sccp_source_reference));
+
+	ret = _send_msg(msgb);
+	msgb_free(msgb);
+
+	/*
+	 * Remove from the list of active connections and set the state. User code
+	 * should now free the entry.
+	 */
+	llist_del(&connection->list);
+	_sccp_set_connection_state(connection, SCCP_CONNECTION_STATE_RELEASE_COMPLETE);
+
+	return ret;
+}
+
+/* connection released, send a released confirm */
+static int _sccp_handle_connection_released(struct msgb *data)
+{
+	static int header_size = sizeof(struct sccp_connection_released);
+	static int optional_offset = offsetof(struct sccp_connection_released, optional_start);
+
+	struct sccp_optional_data optional_data;
+	struct sccp_connection_released *rls = (struct sccp_connection_released *)data->l2h;
+	struct sccp_connection *conn;
+
+	/* we don't have enough size for the struct */
+	if (msgb_l2len(data) < header_size) {
+		DEBUGP(DSCCP, "msgb > header_size %u %u\n",
+		        msgb_l2len(data), header_size);
+		return -1;
+	}
+
+	/* lookup if we have a connection with the given reference */
+	llist_for_each_entry(conn, &sccp_connections, list) {
+		if (conn->data_cb
+		    && memcmp(&conn->source_local_reference,
+			      &rls->destination_local_reference,
+			      sizeof(conn->source_local_reference)) == 0
+		    && memcmp(&conn->destination_local_reference,
+			      &rls->source_local_reference,
+			      sizeof(conn->destination_local_reference)) == 0) {
+		    goto found;
+		}
+	}
+
+
+	DEBUGP(DSCCP, "Unknown connection was released.\n");
+	return -1;
+
+	/* we have found a connection */
+found:
+	memset(&optional_data, 0, sizeof(optional_data));
+	if (_sccp_parse_optional_data(optional_offset + rls->optional_start, data, &optional_data) != 0) {
+		DEBUGP(DSCCP, "parsing of optional data failed.\n");
+		return -1;
+	}
+
+	/* optional data */
+	if (optional_data.data_len != 0 && conn->data_cb) {
+		data->l3h = &data->l2h[optional_data.data_start];
+		conn->data_cb(conn, data, optional_data.data_len);
+	}
+
+	/* generate a response */
+	if (_sccp_send_connection_release_complete(conn) != 0) {
+		DEBUGP(DSCCP, "Sending release confirmed failed\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int _sccp_handle_connection_refused(struct msgb *msgb)
+{
+	static const u_int32_t header_size =
+			sizeof(struct sccp_connection_refused);
+	static int optional_offset = offsetof(struct sccp_connection_refused, optional_start);
+
+	struct sccp_optional_data optional_data;
+	struct sccp_connection *conn;
+	struct sccp_connection_refused *ref;
+
+	/* header check */
+	if (msgb_l2len(msgb) < header_size) {
+		DEBUGP(DSCCP, "msgb < header_size %u %u\n",
+		        msgb_l2len(msgb), header_size);
+		return -1;
+	}
+
+	ref = (struct sccp_connection_refused *) msgb->l2h;
+
+	/* lookup if we have a connection with the given reference */
+	llist_for_each_entry(conn, &sccp_connections, list) {
+		if (conn->incoming == 0 && conn->data_cb
+		    && memcmp(&conn->source_local_reference,
+			      &ref->destination_local_reference,
+			      sizeof(conn->source_local_reference)) == 0) {
+		    goto found;
+		}
+	}
+
+	DEBUGP(DSCCP, "Refused but no connection found\n");
+	return -1;
+
+found:
+	memset(&optional_data, 0, sizeof(optional_data));
+	if (_sccp_parse_optional_data(optional_offset + ref->optional_start, msgb, &optional_data) != 0) {
+		DEBUGP(DSCCP, "parsing of optional data failed.\n");
+		return -1;
+	}
+
+	/* optional data */
+	if (optional_data.data_len != 0 && conn->data_cb) {
+		msgb->l3h = &msgb->l2h[optional_data.data_start];
+		conn->data_cb(conn, msgb, optional_data.data_len);
+	}
+
+
+	llist_del(&conn->list);
+	_sccp_set_connection_state(conn, SCCP_CONNECTION_STATE_REFUSED);
+	return 0;
+}
+
+static int _sccp_handle_connection_confirm(struct msgb *msgb)
+{
+	static u_int32_t header_size =
+		    sizeof(struct sccp_connection_confirm);
+	static const u_int32_t optional_offset =
+			offsetof(struct sccp_connection_confirm, optional_start);
+
+	struct sccp_optional_data optional_data;
+	struct sccp_connection *conn;
+	struct sccp_connection_confirm *con;
+
+	/* header check */
+	if (msgb_l2len(msgb) < header_size) {
+		DEBUGP(DSCCP, "msgb < header_size %u %u\n",
+		        msgb_l2len(msgb), header_size);
+		return -1;
+	}
+
+	con = (struct sccp_connection_confirm *) msgb->l2h;
+
+	/* lookup if we have a connection with the given reference */
+	llist_for_each_entry(conn, &sccp_connections, list) {
+		if (conn->incoming == 0 && conn->data_cb
+		    && memcmp(&conn->source_local_reference,
+			      &con->destination_local_reference,
+			      sizeof(conn->source_local_reference)) == 0) {
+		    goto found;
+		}
+	}
+
+	DEBUGP(DSCCP, "Confirmed but no connection found\n");
+	return -1;
+
+found:
+	/* copy the addresses of the connection */
+	conn->destination_local_reference = con->source_local_reference;
+	_sccp_set_connection_state(conn, SCCP_CONNECTION_STATE_ESTABLISHED);
+
+	memset(&optional_data, 0, sizeof(optional_data));
+	if (_sccp_parse_optional_data(optional_offset + con->optional_start, msgb, &optional_data) != 0) {
+		DEBUGP(DSCCP, "parsing of optional data failed.\n");
+		return -1;
+	}
+
+	/* optional data */
+	if (optional_data.data_len != 0 && conn->data_cb) {
+		msgb->l3h = &msgb->l2h[optional_data.data_start];
+		conn->data_cb(conn, msgb, optional_data.data_len);
+	}
+
+	return 0;
+}
+
+
+int sccp_system_init(int (*outgoing)(struct msgb *data, void *ctx), void *ctx)
+{
+	sccp_system.write_data = outgoing;
+	sccp_system.write_context = ctx;
+
+	return 0;
+}
+
+/* oh my god a real SCCP packet. need to dispatch it now */
+int sccp_system_incoming(struct msgb *msgb)
+{
+	if (msgb_l2len(msgb) < 1 ) {
+		DEBUGP(DSCCP, "Too short packet\n");
+		return -1;
+	}
+
+	int type = msgb->l2h[0];
+
+	switch(type) {
+	case SCCP_MSG_TYPE_CR:
+		return _sccp_handle_connection_request(msgb);
+		break;
+	case SCCP_MSG_TYPE_RLSD:
+		return _sccp_handle_connection_released(msgb);
+		break;
+	case SCCP_MSG_TYPE_CREF:
+		return _sccp_handle_connection_refused(msgb);
+		break;
+	case SCCP_MSG_TYPE_CC:
+		return _sccp_handle_connection_confirm(msgb);
+		break;
+	case SCCP_MSG_TYPE_RLC:
+		return _sccp_handle_connection_release_complete(msgb);
+		break;
+	case SCCP_MSG_TYPE_DT1:
+		return _sccp_handle_connection_dt1(msgb);
+		break;
+	case SCCP_MSG_TYPE_UDT:
+		return _sccp_handle_read(msgb);
+		break;
+	default:
+		DEBUGP(DSCCP, "unimplemented msg type: %d\n", type);
+	};
+
+	return -1;
+}
+
+/* create a packet from the data */
+int sccp_connection_write(struct sccp_connection *connection, struct msgb *data)
+{
+	if (connection->connection_state < SCCP_CONNECTION_STATE_CONFIRM
+	    || connection->connection_state > SCCP_CONNECTION_STATE_ESTABLISHED) {
+		DEBUGP(DSCCP, "sccp_connection_write: Wrong connection state: %p %d\n",
+		       connection, connection->connection_state);
+		return -1;
+	}
+
+	return _sccp_send_connection_data(connection, data);
+}
+
+/* send a connection release and wait for the connection released */
+int sccp_connection_close(struct sccp_connection *connection, int cause)
+{
+	if (connection->connection_state < SCCP_CONNECTION_STATE_CONFIRM
+	    || connection->connection_state > SCCP_CONNECTION_STATE_ESTABLISHED) {
+		DEBUGPC(DSCCP, "Can not close the connection. It was never opened: %p %d\n",
+			connection, connection->connection_state);
+		return -1;
+	}
+
+	return _sccp_send_connection_released(connection, cause);
+}
+
+int sccp_connection_free(struct sccp_connection *connection)
+{
+	if (connection->connection_state > SCCP_CONNECTION_STATE_NONE
+	    && connection->connection_state < SCCP_CONNECTION_STATE_RELEASE_COMPLETE) {
+		DEBUGP(DSCCP, "The connection needs to be released before it is freed");
+		return -1;
+	}
+
+	talloc_free(connection);
+	return 0;
+}
+
+struct sccp_connection *sccp_connection_socket(void)
+{
+	return talloc_zero(tall_sccp_ctx, struct sccp_connection);
+}
+
+int sccp_connection_connect(struct sccp_connection *conn,
+			    const struct sockaddr_sccp *local,
+			    struct msgb *data)
+{
+	return _sccp_send_connection_request(conn, local, data);
+}
+
+int sccp_connection_set_incoming(const struct sockaddr_sccp *sock,
+				 int (*accept_cb)(struct sccp_connection *, void *), void *context)
+{
+	struct sccp_data_callback *cb;
+
+	if (!sock)
+		return -2;
+
+	cb = _find_ssn(sock->sccp_ssn);
+	if (!cb)
+		return -1;
+
+	cb->accept_cb = accept_cb;
+	cb->accept_context = context;
+	return 0;
+}
+
+int sccp_write(struct msgb *data, const struct sockaddr_sccp *in,
+	       const struct sockaddr_sccp *out, int class)
+{
+	return _sccp_send_data(class, in, out, data);
+}
+
+int sccp_set_read(const struct sockaddr_sccp *sock,
+		  int (*read_cb)(struct msgb *, unsigned int, void *), void *context)
+{
+	struct sccp_data_callback *cb;
+
+	if (!sock)
+		return -2;
+
+	cb  = _find_ssn(sock->sccp_ssn);
+	if (!cb)
+		return -1;
+
+	cb->read_cb = read_cb;
+	cb->read_context = context;
+	return 0;
+}
+
+static_assert(sizeof(struct sccp_source_reference) <= sizeof(u_int32_t), enough_space);
+
+u_int32_t sccp_src_ref_to_int(struct sccp_source_reference *ref)
+{
+	u_int32_t src_ref = 0;
+	memcpy(&src_ref, ref, sizeof(*ref));
+	return src_ref;
+}
+
+struct sccp_source_reference sccp_src_ref_from_int(u_int32_t int_ref)
+{
+	struct sccp_source_reference ref;
+	memcpy(&ref, &int_ref, sizeof(ref));
+	return ref;
+}
+
+static __attribute__((constructor)) void on_dso_load(void)
+{
+	tall_sccp_ctx = talloc_named_const(NULL, 1, "sccp");
+}
+
+static __attribute__((destructor)) void on_dso_unload(void)
+{
+	talloc_report_full(tall_sccp_ctx, stderr);
+}