1 files changed, 893 insertions, 0 deletions

diff --git a/src/osmo-bsc_nat/bsc_nat_utils.c b/src/osmo-bsc_nat/bsc_nat_utils.c
new file mode 100644
index 000000000..cd294ccfb
--- /dev/null
+++ b/src/osmo-bsc_nat/bsc_nat_utils.c
@@ -0,0 +1,893 @@
+
+/* BSC Multiplexer/NAT Utilities */
+
+/*
+ * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010 by On-Waves
+ * 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 <openbsc/bsc_nat.h>
+#include <openbsc/bsc_nat_sccp.h>
+#include <openbsc/bsc_msc.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/debug.h>
+#include <openbsc/ipaccess.h>
+#include <openbsc/vty.h>
+
+#include <osmocore/linuxlist.h>
+#include <osmocore/talloc.h>
+#include <osmocore/gsm0808.h>
+
+#include <osmocore/protocol/gsm_08_08.h>
+
+#include <osmocom/sccp/sccp.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+
+static const struct rate_ctr_desc bsc_cfg_ctr_description[] = {
+	[BCFG_CTR_SCCP_CONN]     = { "sccp.conn",      "SCCP Connections         "},
+	[BCFG_CTR_SCCP_CALLS]    = { "sccp.calls",     "SCCP Assignment Commands "},
+	[BCFG_CTR_NET_RECONN]    = { "net.reconnects", "Network reconnects       "},
+	[BCFG_CTR_DROPPED_SCCP]  = { "dropped.sccp",   "Dropped SCCP connections."},
+	[BCFG_CTR_DROPPED_CALLS] = { "dropped.calls",  "Dropped active calls.    "},
+	[BCFG_CTR_REJECTED_CR]   = { "rejected.cr",    "Rejected CR due filter   "},
+	[BCFG_CTR_REJECTED_MSG]  = { "rejected.msg",   "Rejected MSG due filter  "},
+	[BCFG_CTR_ILL_PACKET]    = { "rejected.ill",   "Rejected due parse error "},
+	[BCFG_CTR_CON_TYPE_LU]   = { "conn.lu",        "Conn Location Update     "},
+	[BCFG_CTR_CON_CMSERV_RQ] = { "conn.rq",        "Conn CM Service Req      "},
+	[BCFG_CTR_CON_PAG_RESP]  = { "conn.pag",       "Conn Paging Response     "},
+	[BCFG_CTR_CON_SSA]       = { "conn.ssa",       "Conn USSD                "},
+	[BCFG_CTR_CON_OTHER]     = { "conn.other",     "Conn Other               "},
+};
+
+static const struct rate_ctr_group_desc bsc_cfg_ctrg_desc = {
+	.group_name_prefix = "nat.bsc",
+	.group_description = "NAT BSC Statistics",
+	.num_ctr = ARRAY_SIZE(bsc_cfg_ctr_description),
+	.ctr_desc = bsc_cfg_ctr_description,
+};
+
+static const struct rate_ctr_desc acc_list_ctr_description[] = {
+	[ACC_LIST_BSC_FILTER]	= { "access-list.bsc-filter", "Rejected by rule for BSC"},
+	[ACC_LIST_NAT_FILTER]	= { "access-list.nat-filter", "Rejected by rule for NAT"},
+};
+
+static const struct rate_ctr_group_desc bsc_cfg_acc_list_desc = {
+	.group_name_prefix = "nat.filter",
+	.group_description = "NAT Access-List Statistics",
+	.num_ctr = ARRAY_SIZE(acc_list_ctr_description),
+	.ctr_desc = acc_list_ctr_description,
+};
+
+struct bsc_nat *bsc_nat_alloc(void)
+{
+	struct bsc_nat *nat = talloc_zero(tall_bsc_ctx, struct bsc_nat);
+	if (!nat)
+		return NULL;
+
+	INIT_LLIST_HEAD(&nat->sccp_connections);
+	INIT_LLIST_HEAD(&nat->bsc_connections);
+	INIT_LLIST_HEAD(&nat->bsc_configs);
+	INIT_LLIST_HEAD(&nat->access_lists);
+
+	nat->stats.sccp.conn = counter_alloc("nat.sccp.conn");
+	nat->stats.sccp.calls = counter_alloc("nat.sccp.calls");
+	nat->stats.bsc.reconn = counter_alloc("nat.bsc.conn");
+	nat->stats.bsc.auth_fail = counter_alloc("nat.bsc.auth_fail");
+	nat->stats.msc.reconn = counter_alloc("nat.msc.conn");
+	nat->stats.ussd.reconn = counter_alloc("nat.ussd.conn");
+	nat->msc_ip = talloc_strdup(nat, "127.0.0.1");
+	nat->msc_port = 5000;
+	nat->auth_timeout = 2;
+	nat->ping_timeout = 20;
+	nat->pong_timeout = 5;
+	return nat;
+}
+
+void bsc_nat_set_msc_ip(struct bsc_nat *nat, const char *ip)
+{
+	bsc_replace_string(nat, &nat->msc_ip, ip);
+}
+
+struct bsc_connection *bsc_connection_alloc(struct bsc_nat *nat)
+{
+	struct bsc_connection *con = talloc_zero(nat, struct bsc_connection);
+	if (!con)
+		return NULL;
+
+	con->nat = nat;
+	write_queue_init(&con->write_queue, 100);
+	return con;
+}
+
+struct bsc_config *bsc_config_alloc(struct bsc_nat *nat, const char *token)
+{
+	struct bsc_config *conf = talloc_zero(nat, struct bsc_config);
+	if (!conf)
+		return NULL;
+
+	conf->token = talloc_strdup(conf, token);
+	conf->nr = nat->num_bsc;
+	conf->nat = nat;
+	conf->max_endpoints = 32;
+
+	INIT_LLIST_HEAD(&conf->lac_list);
+
+	llist_add_tail(&conf->entry, &nat->bsc_configs);
+	++nat->num_bsc;
+
+	conf->stats.ctrg = rate_ctr_group_alloc(conf, &bsc_cfg_ctrg_desc, conf->nr);
+	if (!conf->stats.ctrg) {
+		talloc_free(conf);
+		return NULL;
+	}
+
+	return conf;
+}
+
+void bsc_config_free(struct bsc_config *cfg)
+{
+	rate_ctr_group_free(cfg->stats.ctrg);
+}
+
+void bsc_config_add_lac(struct bsc_config *cfg, int _lac)
+{
+	struct bsc_lac_entry *lac;
+
+	llist_for_each_entry(lac, &cfg->lac_list, entry)
+		if (lac->lac == _lac)
+			return;
+
+	lac = talloc_zero(cfg, struct bsc_lac_entry);
+	if (!lac) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
+		return;
+	}
+
+	lac->lac = _lac;
+	llist_add_tail(&lac->entry, &cfg->lac_list);
+}
+
+void bsc_config_del_lac(struct bsc_config *cfg, int _lac)
+{
+	struct bsc_lac_entry *lac;
+
+	llist_for_each_entry(lac, &cfg->lac_list, entry)
+		if (lac->lac == _lac) {
+			llist_del(&lac->entry);
+			talloc_free(lac);
+			return;
+		}
+}
+
+int bsc_config_handles_lac(struct bsc_config *cfg, int lac_nr)
+{
+	struct bsc_lac_entry *entry;
+
+	llist_for_each_entry(entry, &cfg->lac_list, entry)
+		if (entry->lac == lac_nr)
+			return 1;
+
+	return 0;
+}
+
+void sccp_connection_destroy(struct sccp_connections *conn)
+{
+	LOGP(DNAT, LOGL_DEBUG, "Destroy 0x%x <-> 0x%x mapping for con %p\n",
+	     sccp_src_ref_to_int(&conn->real_ref),
+	     sccp_src_ref_to_int(&conn->patched_ref), conn->bsc);
+	bsc_mgcp_dlcx(conn);
+	llist_del(&conn->list_entry);
+	talloc_free(conn);
+}
+
+struct bsc_connection *bsc_nat_find_bsc(struct bsc_nat *nat, struct msgb *msg, int *lac_out)
+{
+	struct bsc_connection *bsc;
+	int data_length;
+	const uint8_t *data;
+	struct tlv_parsed tp;
+	int i = 0;
+
+	*lac_out = -1;
+
+	if (!msg->l3h || msgb_l3len(msg) < 3) {
+		LOGP(DNAT, LOGL_ERROR, "Paging message is too short.\n");
+		return NULL;
+	}
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l3h + 3, msgb_l3len(msg) - 3, 0, 0);
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST)) {
+		LOGP(DNAT, LOGL_ERROR, "No CellIdentifier List inside paging msg.\n");
+		return NULL;
+	}
+
+	data_length = TLVP_LEN(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
+	data = TLVP_VAL(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
+
+	/* No need to try a different BSS */
+	if (data[0] == CELL_IDENT_BSS) {
+		return NULL;
+	} else if (data[0] != CELL_IDENT_LAC) {
+		LOGP(DNAT, LOGL_ERROR, "Unhandled cell ident discrminator: %d\n", data[0]);
+		return NULL;
+	}
+
+	/* Currently we only handle one BSC */
+	for (i = 1; i < data_length - 1; i += 2) {
+		unsigned int _lac = ntohs(*(unsigned int *) &data[i]);
+		*lac_out = _lac;
+		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;
+
+			return bsc;
+		}
+	}
+
+	return NULL;
+}
+
+int bsc_write_mgcp(struct bsc_connection *bsc, const uint8_t *data, unsigned int length)
+{
+	struct msgb *msg;
+
+	if (length > 4096 - 128) {
+		LOGP(DINP, LOGL_ERROR, "Can not send message of that size.\n");
+		return -1;
+	}
+
+	msg = msgb_alloc_headroom(4096, 128, "to-bsc");
+	if (!msg) {
+		LOGP(DINP, LOGL_ERROR, "Failed to allocate memory for BSC msg.\n");
+		return -1;
+	}
+
+	/* copy the data */
+	msg->l3h = msgb_put(msg, length);
+	memcpy(msg->l3h, data, length);
+
+        return bsc_write(bsc, msg, IPAC_PROTO_MGCP_OLD);
+}
+
+int bsc_write(struct bsc_connection *bsc, struct msgb *msg, int proto)
+{
+	return bsc_do_write(&bsc->write_queue, msg, proto);
+}
+
+int bsc_do_write(struct write_queue *queue, struct msgb *msg, int proto)
+{
+	/* prepend the header */
+	ipaccess_prepend_header(msg, proto);
+	return bsc_write_msg(queue, msg);
+}
+
+int bsc_write_msg(struct write_queue *queue, struct msgb *msg)
+{
+	if (write_queue_enqueue(queue, msg) != 0) {
+		LOGP(DINP, LOGL_ERROR, "Failed to enqueue the write.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	return 0;
+}
+
+int bsc_nat_lst_check_allow(struct bsc_nat_acc_lst *lst, const char *mi_string)
+{
+	struct bsc_nat_acc_lst_entry *entry;
+
+	llist_for_each_entry(entry, &lst->fltr_list, list) {
+		if (!entry->imsi_allow)
+			continue;
+		if (regexec(&entry->imsi_allow_re, mi_string, 0, NULL, 0) == 0)
+			return 0;
+	}
+
+	return 1;
+}
+
+static int lst_check_deny(struct bsc_nat_acc_lst *lst, const char *mi_string)
+{
+	struct bsc_nat_acc_lst_entry *entry;
+
+	llist_for_each_entry(entry, &lst->fltr_list, list) {
+		if (!entry->imsi_deny)
+			continue;
+		if (regexec(&entry->imsi_deny_re, mi_string, 0, NULL, 0) == 0)
+			return 0;
+	}
+
+	return 1;
+}
+
+/* apply white/black list */
+static int auth_imsi(struct bsc_connection *bsc, const char *mi_string)
+{
+	/*
+	 * Now apply blacklist/whitelist of the BSC and the NAT.
+	 * 1.) Allow directly if the IMSI is allowed at the BSC
+	 * 2.) Reject if the IMSI is not allowed at the BSC
+	 * 3.) Reject if the IMSI not allowed at the global level.
+	 * 4.) Allow directly if the IMSI is allowed at the global level
+	 */
+	struct bsc_nat_acc_lst *nat_lst = NULL;
+	struct bsc_nat_acc_lst *bsc_lst = NULL;
+
+	bsc_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->cfg->acc_lst_name);
+	nat_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->nat->acc_lst_name);
+
+
+	if (bsc_lst) {
+		/* 1. BSC allow */
+		if (bsc_nat_lst_check_allow(bsc_lst, mi_string) == 0)
+			return 1;
+
+		/* 2. BSC deny */
+		if (lst_check_deny(bsc_lst, mi_string) == 0) {
+			LOGP(DNAT, LOGL_ERROR,
+			     "Filtering %s by imsi_deny on bsc nr: %d.\n", mi_string, bsc->cfg->nr);
+			rate_ctr_inc(&bsc_lst->stats->ctr[ACC_LIST_BSC_FILTER]);
+			return -2;
+		}
+
+	}
+
+	/* 3. NAT deny */
+	if (nat_lst) {
+		if (lst_check_deny(nat_lst, mi_string) == 0) {
+			LOGP(DNAT, LOGL_ERROR,
+			     "Filtering %s by nat imsi_deny on bsc nr: %d.\n", mi_string, bsc->cfg->nr);
+			rate_ctr_inc(&nat_lst->stats->ctr[ACC_LIST_NAT_FILTER]);
+			return -3;
+		}
+	}
+
+	return 1;
+}
+
+static int _cr_check_loc_upd(struct bsc_connection *bsc,
+			     uint8_t *data, unsigned int length,
+			     char **imsi)
+{
+	uint8_t mi_type;
+	struct gsm48_loc_upd_req *lu;
+	char mi_string[GSM48_MI_SIZE];
+
+	if (length < sizeof(*lu)) {
+		LOGP(DNAT, LOGL_ERROR,
+		     "LU does not fit. Length is %d \n", length);
+		return -1;
+	}
+
+	lu = (struct gsm48_loc_upd_req *) data;
+	mi_type = lu->mi[0] & GSM_MI_TYPE_MASK;
+
+	/*
+	 * We can only deal with the IMSI. This will fail for a phone that
+	 * will send the TMSI of a previous network to us.
+	 */
+	if (mi_type != GSM_MI_TYPE_IMSI)
+		return 0;
+
+	gsm48_mi_to_string(mi_string, sizeof(mi_string), lu->mi, lu->mi_len);
+	*imsi = talloc_strdup(bsc, mi_string);
+	return auth_imsi(bsc, mi_string);
+}
+
+static int _cr_check_cm_serv_req(struct bsc_connection *bsc,
+				 uint8_t *data, unsigned int length,
+				 int *con_type, char **imsi)
+{
+	static const uint32_t classmark_offset =
+				offsetof(struct gsm48_service_request, classmark);
+
+	char mi_string[GSM48_MI_SIZE];
+	uint8_t mi_type;
+	int rc;
+	struct gsm48_service_request *req;
+
+	/* unfortunately in Phase1 the classmark2 length is variable */
+
+	if (length < sizeof(*req)) {
+		LOGP(DNAT, LOGL_ERROR,
+		     "CM Serv Req does not fit. Length is %d\n", length);
+		return -1;
+	}
+
+	req = (struct gsm48_service_request *) data;
+	if (req->cm_service_type == 0x8)
+		*con_type = NAT_CON_TYPE_SSA;
+	rc = gsm48_extract_mi((uint8_t *) &req->classmark,
+			      length - classmark_offset, mi_string, &mi_type);
+	if (rc < 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to parse the classmark2/mi. error: %d\n", rc);
+		return -1;
+	}
+
+	/* we have to let the TMSI or such pass */
+	if (mi_type != GSM_MI_TYPE_IMSI)
+		return 0;
+
+	*imsi = talloc_strdup(bsc, mi_string);
+	return auth_imsi(bsc, mi_string);
+}
+
+static int _cr_check_pag_resp(struct bsc_connection *bsc,
+			      uint8_t *data, unsigned int length,
+			      char **imsi)
+{
+	struct gsm48_pag_resp *resp;
+	char mi_string[GSM48_MI_SIZE];
+	uint8_t mi_type;
+
+	if (length < sizeof(*resp)) {
+		LOGP(DNAT, LOGL_ERROR, "PAG RESP does not fit. Length was %d.\n", length);
+		return -1;
+	}
+
+	resp = (struct gsm48_pag_resp *) data;
+	if (gsm48_paging_extract_mi(resp, length, mi_string, &mi_type) < 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to extract the MI.\n");
+		return -1;
+	}
+
+	/* we need to let it pass for now */
+	if (mi_type != GSM_MI_TYPE_IMSI)
+		return 0;
+
+	*imsi = talloc_strdup(bsc, mi_string);
+	return auth_imsi(bsc, mi_string);
+}
+
+static int _dt_check_id_resp(struct bsc_connection *bsc,
+			     uint8_t *data, unsigned int length,
+			     struct sccp_connections *con)
+{
+	char mi_string[GSM48_MI_SIZE];
+	uint8_t mi_type;
+	int ret;
+
+	if (length < 2) {
+		LOGP(DNAT, LOGL_ERROR, "mi does not fit.\n");
+		return -1;
+	}
+
+	if (data[0] < length - 1) {
+		LOGP(DNAT, LOGL_ERROR, "mi length too big.\n");
+		return -2;
+	}
+
+	mi_type = data[1] & GSM_MI_TYPE_MASK;
+	gsm48_mi_to_string(mi_string, sizeof(mi_string), &data[1], data[0]);
+
+	if (mi_type != GSM_MI_TYPE_IMSI)
+		return 0;
+
+	ret = auth_imsi(bsc, mi_string);
+	con->imsi_checked = 1;
+	con->imsi = talloc_strdup(con, mi_string);
+	return ret;
+}
+
+/* Filter out CR data... */
+int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
+			   struct bsc_nat_parsed *parsed, int *con_type,
+			   char **imsi)
+{
+	struct tlv_parsed tp;
+	struct gsm48_hdr *hdr48;
+	int hdr48_len;
+	int len;
+	uint8_t msg_type;
+
+	*con_type = NAT_CON_TYPE_NONE;
+	*imsi = NULL;
+
+	if (parsed->gsm_type != BSS_MAP_MSG_COMPLETE_LAYER_3) {
+		LOGP(DNAT, LOGL_ERROR,
+		     "Rejecting CR message due wrong GSM Type %d\n", parsed->gsm_type);
+		return -1;
+	}
+
+	/* the parsed has had some basic l3 length check */
+	len = msg->l3h[1];
+	if (msgb_l3len(msg) - 3 < len) {
+		LOGP(DNAT, LOGL_ERROR,
+		     "The CR Data has not enough space...\n");
+		return -1;
+	}
+
+	msg->l4h = &msg->l3h[3];
+	len -= 1;
+
+	tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h, len, 0, 0);
+
+	if (!TLVP_PRESENT(&tp, GSM0808_IE_LAYER_3_INFORMATION)) {
+		LOGP(DNAT, LOGL_ERROR, "CR Data does not contain layer3 information.\n");
+		return -1;
+	}
+
+	hdr48_len = TLVP_LEN(&tp, GSM0808_IE_LAYER_3_INFORMATION);
+
+	if (hdr48_len < sizeof(*hdr48)) {
+		LOGP(DNAT, LOGL_ERROR, "GSM48 header does not fit.\n");
+		return -1;
+	}
+
+	hdr48 = (struct gsm48_hdr *) TLVP_VAL(&tp, GSM0808_IE_LAYER_3_INFORMATION);
+
+	msg_type = hdr48->msg_type & 0xbf;
+	if (hdr48->proto_discr == GSM48_PDISC_MM &&
+	    msg_type == GSM48_MT_MM_LOC_UPD_REQUEST) {
+		*con_type = NAT_CON_TYPE_LU;
+		return _cr_check_loc_upd(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48), imsi);
+	} else if (hdr48->proto_discr == GSM48_PDISC_MM &&
+		  msg_type == GSM48_MT_MM_CM_SERV_REQ) {
+		*con_type = NAT_CON_TYPE_CM_SERV_REQ;
+		return _cr_check_cm_serv_req(bsc, &hdr48->data[0],
+					     hdr48_len - sizeof(*hdr48),
+					     con_type, imsi);
+	} else if (hdr48->proto_discr == GSM48_PDISC_RR &&
+		   msg_type == GSM48_MT_RR_PAG_RESP) {
+		*con_type = NAT_CON_TYPE_PAG_RESP;
+		return _cr_check_pag_resp(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48), imsi);
+	} else {
+		/* We only want to filter the above, let other things pass */
+		*con_type = NAT_CON_TYPE_OTHER;
+		return 0;
+	}
+}
+
+struct gsm48_hdr *bsc_unpack_dtap(struct bsc_nat_parsed *parsed,
+				  struct msgb *msg, uint32_t *len)
+{
+	/* gsm_type is actually the size of the dtap */
+	*len = parsed->gsm_type;
+	if (*len < msgb_l3len(msg) - 3) {
+		LOGP(DNAT, LOGL_ERROR, "Not enough space for DTAP.\n");
+		return NULL;
+	}
+
+	if (*len < sizeof(struct gsm48_hdr)) {
+		LOGP(DNAT, LOGL_ERROR, "GSM48 header does not fit.\n");
+		return NULL;
+	}
+
+	msg->l4h = &msg->l3h[3];
+	return (struct gsm48_hdr *) msg->l4h;
+}
+
+int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
+		      struct sccp_connections *con, struct bsc_nat_parsed *parsed)
+{
+	uint32_t len;
+	uint8_t msg_type;
+	struct gsm48_hdr *hdr48;
+
+	if (con->imsi_checked)
+		return 0;
+
+	/* only care about DTAP messages */
+	if (parsed->bssap != BSSAP_MSG_DTAP)
+		return 0;
+
+	hdr48 = bsc_unpack_dtap(parsed, msg, &len);
+	if (!hdr48)
+		return -1;
+
+	msg_type = hdr48->msg_type & 0xbf;
+	if (hdr48->proto_discr == GSM48_PDISC_MM &&
+	    msg_type == GSM48_MT_MM_ID_RESP) {
+		return _dt_check_id_resp(bsc, &hdr48->data[0], len - sizeof(*hdr48), con);
+	} else {
+		return 0;
+	}
+}
+
+void bsc_parse_reg(void *ctx, regex_t *reg, char **imsi, int argc, const char **argv)
+{
+	if (*imsi) {
+		talloc_free(*imsi);
+		*imsi = NULL;
+	}
+	regfree(reg);
+
+	if (argc > 0) {
+		*imsi = talloc_strdup(ctx, argv[0]);
+		regcomp(reg, argv[0], 0);
+	}
+}
+
+static const char *con_types [] = {
+	[NAT_CON_TYPE_NONE] = "n/a",
+	[NAT_CON_TYPE_LU] = "Location Update",
+	[NAT_CON_TYPE_CM_SERV_REQ] = "CM Serv Req",
+	[NAT_CON_TYPE_PAG_RESP] = "Paging Response",
+	[NAT_CON_TYPE_SSA] = "Supplementar Service Activation",
+	[NAT_CON_TYPE_LOCAL_REJECT] = "Local Reject",
+	[NAT_CON_TYPE_OTHER] = "Other",
+};
+
+const char *bsc_con_type_to_string(int type)
+{
+	return con_types[type];
+}
+
+struct bsc_nat_acc_lst *bsc_nat_acc_lst_find(struct bsc_nat *nat, const char *name)
+{
+	struct bsc_nat_acc_lst *lst;
+
+	if (!name)
+		return NULL;
+
+	llist_for_each_entry(lst, &nat->access_lists, list)
+		if (strcmp(lst->name, name) == 0)
+			return lst;
+
+	return NULL;
+}
+
+struct bsc_nat_acc_lst *bsc_nat_acc_lst_get(struct bsc_nat *nat, const char *name)
+{
+	struct bsc_nat_acc_lst *lst;
+
+	lst = bsc_nat_acc_lst_find(nat, name);
+	if (lst)
+		return lst;
+
+	lst = talloc_zero(nat, struct bsc_nat_acc_lst);
+	if (!lst) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate access list");
+		return NULL;
+	}
+
+	/* TODO: get the index right */
+	lst->stats = rate_ctr_group_alloc(lst, &bsc_cfg_acc_list_desc, 0);
+	if (!lst->stats) {
+		talloc_free(lst);
+		return NULL;
+	}
+
+	INIT_LLIST_HEAD(&lst->fltr_list);
+	lst->name = talloc_strdup(lst, name);
+	llist_add_tail(&lst->list, &nat->access_lists);
+	return lst;
+}
+
+void bsc_nat_acc_lst_delete(struct bsc_nat_acc_lst *lst)
+{
+	llist_del(&lst->list);
+	rate_ctr_group_free(lst->stats);
+	talloc_free(lst);
+}
+
+struct bsc_nat_acc_lst_entry *bsc_nat_acc_lst_entry_create(struct bsc_nat_acc_lst *lst)
+{
+	struct bsc_nat_acc_lst_entry *entry;
+
+	entry = talloc_zero(lst, struct bsc_nat_acc_lst_entry);
+	if (!entry)
+		return NULL;
+
+	llist_add_tail(&entry->list, &lst->fltr_list);
+	return entry;
+}
+
+int bsc_nat_msc_is_connected(struct bsc_nat *nat)
+{
+	return nat->msc_con->is_connected;
+}
+
+static const int con_to_ctr[] = {
+	[NAT_CON_TYPE_NONE]		= -1,
+	[NAT_CON_TYPE_LU]		= BCFG_CTR_CON_TYPE_LU,
+	[NAT_CON_TYPE_CM_SERV_REQ]	= BCFG_CTR_CON_CMSERV_RQ,
+	[NAT_CON_TYPE_PAG_RESP]		= BCFG_CTR_CON_PAG_RESP,
+	[NAT_CON_TYPE_SSA]		= BCFG_CTR_CON_SSA,
+	[NAT_CON_TYPE_LOCAL_REJECT]	= -1,
+	[NAT_CON_TYPE_OTHER]		= BCFG_CTR_CON_OTHER,
+};
+
+int bsc_conn_type_to_ctr(struct sccp_connections *conn)
+{
+	return con_to_ctr[conn->con_type];
+}
+
+int bsc_write_cb(struct bsc_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 message to the BSC.\n");
+
+	return rc;
+}
+
+/**
+ * Rewrite non global numbers... according to rules based on the IMSI
+ */
+struct msgb *bsc_nat_rewrite_setup(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *parsed, const char *imsi)
+{
+	struct tlv_parsed tp;
+	struct gsm48_hdr *hdr48;
+	uint32_t len;
+	uint8_t msg_type;
+	unsigned int payload_len;
+	struct gsm_mncc_number called;
+	struct msg_entry *entry;
+	char *new_number = NULL;
+	struct msgb *out, *sccp;
+	uint8_t *outptr;
+	const uint8_t *msgptr;
+	int sec_len;
+
+	if (!imsi || strlen(imsi) < 5)
+		return msg;
+
+	if (!nat->num_rewr)
+		return msg;
+
+	/* only care about DTAP messages */
+	if (parsed->bssap != BSSAP_MSG_DTAP)
+		return msg;
+	if (!parsed->dest_local_ref)
+		return msg;
+
+	hdr48 = bsc_unpack_dtap(parsed, msg, &len);
+	if (!hdr48)
+		return msg;
+
+	msg_type = hdr48->msg_type & 0xbf;
+	if (hdr48->proto_discr != GSM48_PDISC_CC ||
+	    msg_type != GSM48_MT_CC_SETUP)
+		return msg;
+
+	/* decode and rewrite the message */
+	payload_len = len - sizeof(*hdr48);
+	tlv_parse(&tp, &gsm48_att_tlvdef, hdr48->data, payload_len, 0, 0);
+
+	/* no number, well let us ignore it */
+	if (!TLVP_PRESENT(&tp, GSM48_IE_CALLED_BCD))
+		return msg;
+
+	memset(&called, 0, sizeof(called));
+	gsm48_decode_called(&called,
+			    TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) - 1);
+
+	/* check if it looks international and stop */
+	if (called.plan != 1)
+		return msg;
+	if (called.type == 1)
+		return msg;
+	if (strncmp(called.number, "00", 2) == 0)
+		return msg;
+
+	/* need to find a replacement and then fix it */
+	llist_for_each_entry(entry, &nat->num_rewr->entry, list) {
+		regex_t reg;
+		regmatch_t matches[2];
+
+		if (entry->mcc[0] != '*' && strncmp(entry->mcc, imsi, 3) != 0)
+			continue;
+		if (entry->mnc[0] != '*' && strncmp(entry->mnc, imsi + 3, 2) != 0)
+			continue;
+
+		if (entry->text[0] == '+') {
+			LOGP(DNAT, LOGL_ERROR,
+				"Plus is not allowed in the number");
+			continue;
+		}
+
+		/* We have an entry for the IMSI. Need to match now */
+		if (regcomp(&reg, entry->option, REG_EXTENDED) != 0) {
+			LOGP(DNAT, LOGL_ERROR,
+				"Regexp '%s' is not valid.\n", entry->option);
+			continue;
+		}
+
+		/* this regexp matches... */
+		if (regexec(&reg, called.number, 2, matches, 0) == 0 &&
+		    matches[1].rm_eo != -1)
+			new_number = talloc_asprintf(msg, "%s%s",
+					entry->text,
+					&called.number[matches[1].rm_so]);
+		regfree(&reg);
+
+		if (new_number)
+			break;
+	}
+
+	if (!new_number) {
+		LOGP(DNAT, LOGL_DEBUG, "No IMSI match found, returning message.\n");
+		return msg;
+	}
+
+	if (strlen(new_number) > sizeof(called.number)) {
+		LOGP(DNAT, LOGL_ERROR, "Number is too long for structure.\n");
+		talloc_free(new_number);
+		return msg;
+	}
+
+	/*
+	 * Need to create a new message now based on the old onew
+	 * with a new number. We can sadly not patch this in place
+	 * so we will need to regenerate it.
+	 */
+
+	out = msgb_alloc_headroom(4096, 128, "changed-setup");
+	if (!out) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
+		talloc_free(new_number);
+		return msg;
+	}
+
+	/* copy the header */
+	outptr = msgb_put(out, sizeof(*hdr48));
+	memcpy(outptr, hdr48, sizeof(*hdr48));
+
+	/* copy everything up to the number */
+	sec_len = TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) - 2 - &hdr48->data[0];
+	outptr = msgb_put(out, sec_len);
+	memcpy(outptr, &hdr48->data[0], sec_len);
+
+	/* create the new number */
+	if (strncmp(new_number, "00", 2) == 0) {
+		called.type = 1;
+		strncpy(called.number, new_number + 2, sizeof(called.number));
+	} else {
+		strncpy(called.number, new_number, sizeof(called.number));
+	}
+	gsm48_encode_called(out, &called);
+
+	/* copy thre rest */
+	msgptr = TLVP_VAL(&tp, GSM48_IE_CALLED_BCD) +
+		 TLVP_LEN(&tp, GSM48_IE_CALLED_BCD);
+	sec_len = payload_len - (msgptr - &hdr48->data[0]);
+	outptr = msgb_put(out, sec_len);
+	memcpy(outptr, msgptr, sec_len);
+
+	/* wrap with DTAP, SCCP, then IPA. TODO: Stop copying */
+	gsm0808_prepend_dtap_header(out, 0);
+	sccp = sccp_create_dt1(parsed->dest_local_ref, out->data, out->len);
+	if (!sccp) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to allocate.\n");
+		talloc_free(new_number);
+		talloc_free(out);
+		return msg;
+	}
+
+	ipaccess_prepend_header(sccp, IPAC_PROTO_SCCP);
+
+	/* give up memory, we are done */
+	talloc_free(new_number);
+	/* the parsed hangs off from msg but it needs to survive */
+	talloc_steal(sccp, parsed);
+	msgb_free(msg);
+	msgb_free(out);
+	out = NULL;
+	return sccp;
+}
+