/* NS-over-IP proxy */

/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
 * (C) 2010-2013 by On-Waves
 * (C) 2013 by Holger Hans Peter Freyther
 * 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 <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <errno.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <arpa/inet.h>

#include <osmocom/core/talloc.h>
#include <osmocom/core/select.h>
#include <osmocom/core/rate_ctr.h>

#include <osmocom/vty/misc.h>

#include <osmocom/gprs/gprs_ns.h>
#include <osmocom/gprs/gprs_bssgp.h>

#include <openbsc/signal.h>
#include <openbsc/debug.h>
#include <openbsc/gb_proxy.h>

enum gbprox_global_ctr {
	GBPROX_GLOB_CTR_INV_BVCI,
	GBPROX_GLOB_CTR_INV_LAC,
	GBPROX_GLOB_CTR_INV_RAC,
	GBPROX_GLOB_CTR_INV_NSEI,
	GBPROX_GLOB_CTR_PROTO_ERR_BSS,
	GBPROX_GLOB_CTR_PROTO_ERR_SGSN,
	GBPROX_GLOB_CTR_NOT_SUPPORTED_BSS,
	GBPROX_GLOB_CTR_NOT_SUPPORTED_SGSN,
	GBPROX_GLOB_CTR_RESTART_RESET_SGSN,
	GBPROX_GLOB_CTR_TX_ERR_SGSN,
	GBPROX_GLOB_CTR_OTHER_ERR,
};

static const struct rate_ctr_desc global_ctr_description[] = {
	{ "inv-bvci",	    "Invalid BVC Identifier          " },
	{ "inv-lac",	    "Invalid Location Area Code      " },
	{ "inv-rac",	    "Invalid Routing Area Code       " },
	{ "inv-nsei",	    "No BVC established for NSEI     " },
	{ "proto-err.bss",  "BSSGP protocol error      (BSS )" },
	{ "proto-err.sgsn", "BSSGP protocol error      (SGSN)" },
	{ "not-supp.bss",   "Feature not supported     (BSS )" },
	{ "not-supp.sgsn",  "Feature not supported     (SGSN)" },
	{ "restart.sgsn",   "Restarted RESET procedure (SGSN)" },
	{ "tx-err.sgsn",    "NS Transmission error     (SGSN)" },
	{ "error",          "Other error                     " },
};

static const struct rate_ctr_group_desc global_ctrg_desc = {
	.group_name_prefix = "gbproxy.global",
	.group_description = "GBProxy Global Statistics",
	.num_ctr = ARRAY_SIZE(global_ctr_description),
	.ctr_desc = global_ctr_description,
};

static struct rate_ctr_group *global_ctrg = NULL;

static struct rate_ctr_group *get_global_ctrg()
{
	if (global_ctrg)
		return global_ctrg;

	global_ctrg = rate_ctr_group_alloc(tall_bsc_ctx, &global_ctrg_desc, 0);
	return global_ctrg;
}

enum gbprox_peer_ctr {
	GBPROX_PEER_CTR_BLOCKED,
	GBPROX_PEER_CTR_UNBLOCKED,
	GBPROX_PEER_CTR_DROPPED,
	GBPROX_PEER_CTR_INV_NSEI,
	GBPROX_PEER_CTR_TX_ERR,
};

static const struct rate_ctr_desc peer_ctr_description[] = {
	{ "blocked",	  "BVC Block                       " },
	{ "unblocked",	  "BVC Unblock                     " },
	{ "dropped",	  "BVC blocked, dropped packet     " },
	{ "inv-nsei",	  "NSEI mismatch                   " },
	{ "tx-err",       "NS Transmission error           " },
};

static const struct rate_ctr_group_desc peer_ctrg_desc = {
	.group_name_prefix = "gbproxy.peer",
	.group_description = "GBProxy Peer Statistics",
	.num_ctr = ARRAY_SIZE(peer_ctr_description),
	.ctr_desc = peer_ctr_description,
};

struct gbprox_peer {
	struct llist_head list;

	/* NSEI of the peer entity */
	uint16_t nsei;

	/* BVCI used for Point-to-Point to this peer */
	uint16_t bvci;
	int blocked;

	/* Routeing Area that this peer is part of (raw 04.08 encoding) */
	uint8_t ra[6];

	/* Counter */
	struct rate_ctr_group *ctrg;
};

/* Linked list of all Gb peers (except SGSN) */
static LLIST_HEAD(gbprox_bts_peers);

/* Find the gbprox_peer by its BVCI */
static struct gbprox_peer *peer_by_bvci(uint16_t bvci)
{
	struct gbprox_peer *peer;
	llist_for_each_entry(peer, &gbprox_bts_peers, list) {
		if (peer->bvci == bvci)
			return peer;
	}
	return NULL;
}

/* Find the gbprox_peer by its NSEI */
static struct gbprox_peer *peer_by_nsei(uint16_t nsei)
{
	struct gbprox_peer *peer;
	llist_for_each_entry(peer, &gbprox_bts_peers, list) {
		if (peer->nsei == nsei)
			return peer;
	}
	return NULL;
}

/* look-up a peer by its Routeing Area Code (RAC) */
static struct gbprox_peer *peer_by_rac(const uint8_t *ra)
{
	struct gbprox_peer *peer;
	llist_for_each_entry(peer, &gbprox_bts_peers, list) {
		if (!memcmp(peer->ra, ra, 6))
			return peer;
	}
	return NULL;
}

/* look-up a peer by its Location Area Code (LAC) */
static struct gbprox_peer *peer_by_lac(const uint8_t *la)
{
	struct gbprox_peer *peer;
	llist_for_each_entry(peer, &gbprox_bts_peers, list) {
		if (!memcmp(peer->ra, la, 5))
			return peer;
	}
	return NULL;
}

static int check_peer_nsei(struct gbprox_peer *peer, uint16_t nsei)
{
	if (peer->nsei != nsei) {
		LOGP(DGPRS, LOGL_NOTICE, "Peer entry doesn't match current NSEI "
		     "BVCI=%u via NSEI=%u (expected NSEI=%u)\n",
		     peer->bvci, nsei, peer->nsei);
		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_INV_NSEI]);
		return 1;
	}

	return 0;
}

static struct gbprox_peer *peer_alloc(uint16_t bvci)
{
	struct gbprox_peer *peer;

	peer = talloc_zero(tall_bsc_ctx, struct gbprox_peer);
	if (!peer)
		return NULL;

	peer->bvci = bvci;
	peer->ctrg = rate_ctr_group_alloc(peer, &peer_ctrg_desc, bvci);

	llist_add(&peer->list, &gbprox_bts_peers);

	return peer;
}

static void peer_free(struct gbprox_peer *peer)
{
	rate_ctr_group_free(peer->ctrg);
	llist_del(&peer->list);
	talloc_free(peer);
}

/* FIXME: this needs to go to libosmocore/msgb.c */
static struct msgb *msgb_copy(const struct msgb *msg, const char *name)
{
	struct libgb_msgb_cb *old_cb, *new_cb;
	struct msgb *new_msg;

	new_msg = msgb_alloc(msg->data_len, name);
	if (!new_msg)
		return NULL;

	/* copy data */
	memcpy(new_msg->_data, msg->_data, new_msg->data_len);

	/* copy header */
	new_msg->len = msg->len;
	new_msg->data += msg->data - msg->_data;
	new_msg->head += msg->head - msg->_data;
	new_msg->tail += msg->tail - msg->_data;

	new_msg->l1h = new_msg->_data + (msg->l1h - msg->_data);
	new_msg->l2h = new_msg->_data + (msg->l2h - msg->_data);
	new_msg->l3h = new_msg->_data + (msg->l3h - msg->_data);
	new_msg->l4h = new_msg->_data + (msg->l4h - msg->_data);

	/* copy GB specific data */
	old_cb = LIBGB_MSGB_CB(msg);
	new_cb = LIBGB_MSGB_CB(new_msg);

	new_cb->bssgph = new_msg->_data + (old_cb->bssgph - msg->_data);
	new_cb->llch = new_msg->_data + (old_cb->llch - msg->_data);

	/* bssgp_cell_id is a pointer into the old msgb, so we need to make
	 * it a pointer into the new msgb */
	new_cb->bssgp_cell_id = new_msg->_data + (old_cb->bssgp_cell_id - msg->_data);
	new_cb->nsei = old_cb->nsei;
	new_cb->bvci = old_cb->bvci;
	new_cb->tlli = old_cb->tlli;

	return new_msg;
}

/* strip off the NS header */
static void strip_ns_hdr(struct msgb *msg)
{
	int strip_len = msgb_bssgph(msg) - msg->data;
	msgb_pull(msg, strip_len);
}

/* feed a message down the NS-VC associated with the specified peer */
static int gbprox_relay2sgsn(struct msgb *old_msg, uint16_t ns_bvci)
{
	/* create a copy of the message so the old one can
	 * be free()d safely when we return from gbprox_rcvmsg() */
	struct msgb *msg = msgb_copy(old_msg, "msgb_relay2sgsn");
	int rc;

	DEBUGP(DGPRS, "NSEI=%u proxying BTS->SGSN (NS_BVCI=%u, NSEI=%u)\n",
		msgb_nsei(msg), ns_bvci, gbcfg.nsip_sgsn_nsei);

	msgb_bvci(msg) = ns_bvci;
	msgb_nsei(msg) = gbcfg.nsip_sgsn_nsei;

	strip_ns_hdr(msg);

	rc = gprs_ns_sendmsg(bssgp_nsi, msg);
	if (rc < 0)
		rate_ctr_inc(&get_global_ctrg()->ctr[GBPROX_GLOB_CTR_TX_ERR_SGSN]);

	return rc;
}

/* feed a message down the NS-VC associated with the specified peer */
static int gbprox_relay2peer(struct msgb *old_msg, struct gbprox_peer *peer,
			  uint16_t ns_bvci)
{
	/* create a copy of the message so the old one can
	 * be free()d safely when we return from gbprox_rcvmsg() */
	struct msgb *msg = msgb_copy(old_msg, "msgb_relay2peer");
	int rc;

	DEBUGP(DGPRS, "NSEI=%u proxying SGSN->BSS (NS_BVCI=%u, NSEI=%u)\n",
		msgb_nsei(msg), ns_bvci, peer->nsei);

	msgb_bvci(msg) = ns_bvci;
	msgb_nsei(msg) = peer->nsei;

	/* Strip the old NS header, it will be replaced with a new one */
	strip_ns_hdr(msg);

	rc = gprs_ns_sendmsg(bssgp_nsi, msg);
	if (rc < 0)
		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_TX_ERR]);

	return rc;
}

static int block_unblock_peer(uint16_t ptp_bvci, uint8_t pdu_type)
{
	struct gbprox_peer *peer;

	peer = peer_by_bvci(ptp_bvci);
	if (!peer) {
		LOGP(DGPRS, LOGL_ERROR, "BVCI=%u: Cannot find BSS\n",
			ptp_bvci);
		rate_ctr_inc(&get_global_ctrg()->ctr[GBPROX_GLOB_CTR_INV_BVCI]);
		return -ENOENT;
	}

	switch (pdu_type) {
	case BSSGP_PDUT_BVC_BLOCK_ACK:
		peer->blocked = 1;
		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_BLOCKED]);
		break;
	case BSSGP_PDUT_BVC_UNBLOCK_ACK:
		peer->blocked = 0;
		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_UNBLOCKED]);
		break;
	default:
		break;
	}
	return 0;
}

/* Send a message to a peer identified by ptp_bvci but using ns_bvci
 * in the NS hdr */
static int gbprox_relay2bvci(struct msgb *msg, uint16_t ptp_bvci,
			  uint16_t ns_bvci)
{
	struct gbprox_peer *peer;

	peer = peer_by_bvci(ptp_bvci);
	if (!peer) {
		LOGP(DGPRS, LOGL_ERROR, "BVCI=%u: Cannot find BSS\n",
			ptp_bvci);
		rate_ctr_inc(&get_global_ctrg()->ctr[GBPROX_GLOB_CTR_INV_BVCI]);
		return -ENOENT;
	}

	return gbprox_relay2peer(msg, peer, ns_bvci);
}

int bssgp_prim_cb(struct osmo_prim_hdr *oph, void *ctx)
{
	return 0;
}

/* Receive an incoming signalling message from a BSS-side NS-VC */
static int gbprox_rx_sig_from_bss(struct msgb *msg, uint16_t nsei,
				  uint16_t ns_bvci)
{
	struct bssgp_normal_hdr *bgph = (struct bssgp_normal_hdr *) msgb_bssgph(msg);
	struct tlv_parsed tp;
	uint8_t pdu_type = bgph->pdu_type;
	int data_len = msgb_bssgp_len(msg) - sizeof(*bgph);
	struct gbprox_peer *from_peer;
	struct gprs_ra_id raid;

	if (ns_bvci != 0 && ns_bvci != 1) {
		LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u BVCI=%u is not signalling\n",
			nsei, ns_bvci);
		return -EINVAL;
	}

	/* we actually should never see those two for BVCI == 0, but double-check
	 * just to make sure  */
	if (pdu_type == BSSGP_PDUT_UL_UNITDATA ||
	    pdu_type == BSSGP_PDUT_DL_UNITDATA) {
		LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u UNITDATA not allowed in "
			"signalling\n", nsei);
		return -EINVAL;
	}

	bssgp_tlv_parse(&tp, bgph->data, data_len);

	switch (pdu_type) {
	case BSSGP_PDUT_SUSPEND:
	case BSSGP_PDUT_RESUME:
		/* We implement RAC snooping during SUSPEND/RESUME, since
		 * it establishes a relationsip between BVCI/peer and the
		 * routeing area code.  The snooped information is then
		 * used for routing the {SUSPEND,RESUME}_[N]ACK back to
		 * the correct BSSGP */
		if (!TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA))
			goto err_mand_ie;
		from_peer = peer_by_nsei(nsei);
		if (!from_peer)
			goto err_no_peer;
		memcpy(from_peer->ra, TLVP_VAL(&tp, BSSGP_IE_ROUTEING_AREA),
			sizeof(from_peer->ra));
		gsm48_parse_ra(&raid, from_peer->ra);
		LOGP(DGPRS, LOGL_INFO, "NSEI=%u BSSGP SUSPEND/RESUME "
			"RAC snooping: RAC %u-%u-%u-%u behind BVCI=%u\n",
			nsei, raid.mcc, raid.mnc, raid.lac,
			raid.rac , from_peer->bvci);
		/* FIXME: This only supports one BSS per RA */
		break;
	case BSSGP_PDUT_BVC_RESET:
		/* If we receive a BVC reset on the signalling endpoint, we
		 * don't want the SGSN to reset, as the signalling endpoint
		 * is common for all point-to-point BVCs (and thus all BTS) */
		if (TLVP_PRESENT(&tp, BSSGP_IE_BVCI)) {
			uint16_t bvci = ntohs(tlvp_val16_unal(&tp, BSSGP_IE_BVCI));
			LOGP(DGPRS, LOGL_INFO, "NSEI=%u Rx BVC RESET (BVCI=%u)\n",
				nsei, bvci);
			if (bvci == 0) {
				/* FIXME: only do this if SGSN is alive! */
				LOGP(DGPRS, LOGL_INFO, "NSEI=%u Tx fake "
					"BVC RESET ACK of BVCI=0\n", nsei);
				return bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_RESET_ACK,
							    nsei, 0, ns_bvci);
			}
			from_peer = peer_by_bvci(bvci);
			if (!from_peer) {
				/* if a PTP-BVC is reset, and we don't know that
				 * PTP-BVCI yet, we should allocate a new peer */
				LOGP(DGPRS, LOGL_INFO, "Allocationg new peer for "
				     "BVCI=%u via NSEI=%u\n", bvci, nsei);
				from_peer = peer_alloc(bvci);
				from_peer->nsei = nsei;
			}
			check_peer_nsei(from_peer, nsei);
			if (TLVP_PRESENT(&tp, BSSGP_IE_CELL_ID)) {
				struct gprs_ra_id raid;
				/* We have a Cell Identifier present in this
				 * PDU, this means we can extend our local
				 * state information about this particular cell
				 * */
				memcpy(from_peer->ra,
					TLVP_VAL(&tp, BSSGP_IE_CELL_ID),
					sizeof(from_peer->ra));
				gsm48_parse_ra(&raid, from_peer->ra);
				LOGP(DGPRS, LOGL_INFO, "NSEI=%u/BVCI=%u "
				     "Cell ID %u-%u-%u-%u\n", nsei,
				     bvci, raid.mcc, raid.mnc, raid.lac,
				     raid.rac);
			}
		}
		break;
	}

	/* Normally, we can simply pass on all signalling messages from BSS to
	 * SGSN */
	return gbprox_relay2sgsn(msg, ns_bvci);
err_no_peer:
	LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(BSS) cannot find peer based on NSEI\n",
		nsei);
	rate_ctr_inc(&get_global_ctrg()->ctr[GBPROX_GLOB_CTR_INV_NSEI]);
	return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, NULL, msg);
err_mand_ie:
	LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(BSS) missing mandatory RA IE\n",
		nsei);
	rate_ctr_inc(&get_global_ctrg()->ctr[GBPROX_GLOB_CTR_PROTO_ERR_BSS]);
	return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
}

/* Receive paging request from SGSN, we need to relay to proper BSS */
static int gbprox_rx_paging(struct msgb *msg, struct tlv_parsed *tp,
			    uint32_t nsei, uint16_t ns_bvci)
{
	struct gbprox_peer *peer = NULL;
	int errctr = GBPROX_GLOB_CTR_PROTO_ERR_SGSN;

	LOGP(DGPRS, LOGL_INFO, "NSEI=%u(SGSN) BSSGP PAGING ",
		nsei);
	if (TLVP_PRESENT(tp, BSSGP_IE_BVCI)) {
		uint16_t bvci = ntohs(tlvp_val16_unal(tp, BSSGP_IE_BVCI));
		LOGPC(DGPRS, LOGL_INFO, "routing by BVCI to peer BVCI=%u\n",
			bvci);
		errctr = GBPROX_GLOB_CTR_OTHER_ERR;
	} else if (TLVP_PRESENT(tp, BSSGP_IE_ROUTEING_AREA)) {
		peer = peer_by_rac(TLVP_VAL(tp, BSSGP_IE_ROUTEING_AREA));
		LOGPC(DGPRS, LOGL_INFO, "routing by RAC to peer BVCI=%u\n",
			peer ? peer->bvci : -1);
		errctr = GBPROX_GLOB_CTR_INV_RAC;
	} else if (TLVP_PRESENT(tp, BSSGP_IE_LOCATION_AREA)) {
		peer = peer_by_lac(TLVP_VAL(tp, BSSGP_IE_LOCATION_AREA));
		LOGPC(DGPRS, LOGL_INFO, "routing by LAC to peer BVCI=%u\n",
			peer ? peer->bvci : -1);
		errctr = GBPROX_GLOB_CTR_INV_LAC;
	} else
		LOGPC(DGPRS, LOGL_INFO, "\n");

	if (!peer) {
		LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(SGSN) BSSGP PAGING: "
			"unable to route, missing IE\n", nsei);
		rate_ctr_inc(&get_global_ctrg()->ctr[errctr]);
		return -EINVAL;
	}
	return gbprox_relay2peer(msg, peer, ns_bvci);
}

/* Receive an incoming BVC-RESET message from the SGSN */
static int rx_reset_from_sgsn(struct msgb *msg, struct tlv_parsed *tp,
			      uint32_t nsei, uint16_t ns_bvci)
{
	struct gbprox_peer *peer;
	uint16_t ptp_bvci;

	if (!TLVP_PRESENT(tp, BSSGP_IE_BVCI)) {
		rate_ctr_inc(&get_global_ctrg()->
			     ctr[GBPROX_GLOB_CTR_PROTO_ERR_SGSN]);
		return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE,
				       NULL, msg);
	}
	ptp_bvci = ntohs(tlvp_val16_unal(tp, BSSGP_IE_BVCI));

	if (ptp_bvci >= 2) {
		/* A reset for a PTP BVC was received, forward it to its
		 * respective peer */
		peer = peer_by_bvci(ptp_bvci);
		if (!peer) {
			LOGP(DGPRS, LOGL_ERROR, "NSEI=%u BVCI=%u: Cannot find BSS\n",
				nsei, ptp_bvci);
			rate_ctr_inc(&get_global_ctrg()->
				     ctr[GBPROX_GLOB_CTR_INV_BVCI]);
			return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI,
					       NULL, msg);
		}
		return gbprox_relay2peer(msg, peer, ns_bvci);
	}

	/* A reset for the Signalling entity has been received
	 * from the SGSN.  As the signalling BVCI is shared
	 * among all the BSS's that we multiplex, it needs to
	 * be relayed  */
	llist_for_each_entry(peer, &gbprox_bts_peers, list)
		gbprox_relay2peer(msg, peer, ns_bvci);

	return 0;
}

/* Receive an incoming signalling message from the SGSN-side NS-VC */
static int gbprox_rx_sig_from_sgsn(struct msgb *msg, uint32_t nsei,
				   uint16_t ns_bvci)
{
	struct bssgp_normal_hdr *bgph = (struct bssgp_normal_hdr *) msgb_bssgph(msg);
	struct tlv_parsed tp;
	uint8_t pdu_type = bgph->pdu_type;
	int data_len = msgb_bssgp_len(msg) - sizeof(*bgph);
	struct gbprox_peer *peer;
	uint16_t bvci;
	int rc = 0;

	if (ns_bvci != 0 && ns_bvci != 1) {
		LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u(SGSN) BVCI=%u is not "
			"signalling\n", nsei, ns_bvci);
		/* FIXME: Send proper error message */
		return -EINVAL;
	}

	/* we actually should never see those two for BVCI == 0, but double-check
	 * just to make sure  */
	if (pdu_type == BSSGP_PDUT_UL_UNITDATA ||
	    pdu_type == BSSGP_PDUT_DL_UNITDATA) {
		LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u(SGSN) UNITDATA not allowed in "
			"signalling\n", nsei);
		return bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, msg);
	}

	rc = bssgp_tlv_parse(&tp, bgph->data, data_len);

	switch (pdu_type) {
	case BSSGP_PDUT_BVC_RESET:
		rc = rx_reset_from_sgsn(msg, &tp, nsei, ns_bvci);
		break;
	case BSSGP_PDUT_FLUSH_LL:
	case BSSGP_PDUT_BVC_RESET_ACK:
		/* simple case: BVCI IE is mandatory */
		if (!TLVP_PRESENT(&tp, BSSGP_IE_BVCI))
			goto err_mand_ie;
		bvci = ntohs(tlvp_val16_unal(&tp, BSSGP_IE_BVCI));
		rc = gbprox_relay2bvci(msg, bvci, ns_bvci);
		break;
	case BSSGP_PDUT_PAGING_PS:
	case BSSGP_PDUT_PAGING_CS:
		/* process the paging request (LAC/RAC lookup) */
		rc = gbprox_rx_paging(msg, &tp, nsei, ns_bvci);
		break;
	case BSSGP_PDUT_STATUS:
		/* Some exception has occurred */
		LOGP(DGPRS, LOGL_NOTICE,
			"NSEI=%u(SGSN) BSSGP STATUS ", nsei);
		if (!TLVP_PRESENT(&tp, BSSGP_IE_CAUSE)) {
			LOGPC(DGPRS, LOGL_NOTICE, "\n");
			goto err_mand_ie;
		}
		LOGPC(DGPRS, LOGL_NOTICE,
			"cause=0x%02x(%s) ", *TLVP_VAL(&tp, BSSGP_IE_CAUSE),
			bssgp_cause_str(*TLVP_VAL(&tp, BSSGP_IE_CAUSE)));
		if (TLVP_PRESENT(&tp, BSSGP_IE_BVCI)) {
			uint16_t bvci = tlvp_val16_unal(&tp, BSSGP_IE_BVCI);
			LOGPC(DGPRS, LOGL_NOTICE,
				"BVCI=%u\n", ntohs(bvci));
		} else
			LOGPC(DGPRS, LOGL_NOTICE, "\n");
		break;
	/* those only exist in the SGSN -> BSS direction */
	case BSSGP_PDUT_SUSPEND_ACK:
	case BSSGP_PDUT_SUSPEND_NACK:
	case BSSGP_PDUT_RESUME_ACK:
	case BSSGP_PDUT_RESUME_NACK:
		/* RAC IE is mandatory */
		if (!TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA))
			goto err_mand_ie;
		peer = peer_by_rac(TLVP_VAL(&tp, BSSGP_IE_ROUTEING_AREA));
		if (!peer)
			goto err_no_peer;
		rc = gbprox_relay2peer(msg, peer, ns_bvci);
		break;
	case BSSGP_PDUT_BVC_BLOCK_ACK:
	case BSSGP_PDUT_BVC_UNBLOCK_ACK:
		if (!TLVP_PRESENT(&tp, BSSGP_IE_BVCI))
			goto err_mand_ie;
		bvci = ntohs(tlvp_val16_unal(&tp, BSSGP_IE_BVCI));
		if (bvci == 0) {
			LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u(SGSN) BSSGP "
			     "%sBLOCK_ACK for signalling BVCI ?!?\n", nsei,
			     pdu_type == BSSGP_PDUT_BVC_UNBLOCK_ACK ? "UN":"");
			/* should we send STATUS ? */
			rate_ctr_inc(&get_global_ctrg()->
				     ctr[GBPROX_GLOB_CTR_INV_BVCI]);
		} else {
			/* Mark BVC as (un)blocked */
			block_unblock_peer(bvci, pdu_type);
		}
		rc = gbprox_relay2bvci(msg, bvci, ns_bvci);
		break;
	case BSSGP_PDUT_SGSN_INVOKE_TRACE:
		LOGP(DGPRS, LOGL_ERROR,
		     "NSEI=%u(SGSN) BSSGP INVOKE TRACE not supported\n",nsei);
		rate_ctr_inc(&get_global_ctrg()->
			     ctr[GBPROX_GLOB_CTR_NOT_SUPPORTED_SGSN]);
		rc = bssgp_tx_status(BSSGP_CAUSE_PDU_INCOMP_FEAT, NULL, msg);
		break;
	default:
		LOGP(DGPRS, LOGL_NOTICE, "BSSGP PDU type 0x%02x unknown\n",
			pdu_type);
		rate_ctr_inc(&get_global_ctrg()->
			     ctr[GBPROX_GLOB_CTR_PROTO_ERR_SGSN]);
		rc = bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, msg);
		break;
	}

	return rc;
err_mand_ie:
	LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(SGSN) missing mandatory IE\n",
		nsei);
	rate_ctr_inc(&get_global_ctrg()->
		     ctr[GBPROX_GLOB_CTR_PROTO_ERR_SGSN]);
	return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
err_no_peer:
	LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(SGSN) cannot find peer based on RAC\n",
		nsei);
	rate_ctr_inc(&get_global_ctrg()-> ctr[GBPROX_GLOB_CTR_INV_RAC]);
	return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, NULL, msg);
}

/* Main input function for Gb proxy */
int gbprox_rcvmsg(struct msgb *msg, uint16_t nsei, uint16_t ns_bvci, uint16_t nsvci)
{
	int rc;
	struct gbprox_peer *peer;
	int remote_end_is_sgsn = nsei == gbcfg.nsip_sgsn_nsei;

	/* Only BVCI=0 messages need special treatment */
	if (ns_bvci == 0 || ns_bvci == 1) {
		if (remote_end_is_sgsn)
			rc = gbprox_rx_sig_from_sgsn(msg, nsei, ns_bvci);
		else
			rc = gbprox_rx_sig_from_bss(msg, nsei, ns_bvci);
	} else {
		peer = peer_by_bvci(ns_bvci);

		/* All other BVCI are PTP and thus can be simply forwarded */
		if (!remote_end_is_sgsn) {
			if (peer)
				check_peer_nsei(peer, nsei);
			return gbprox_relay2sgsn(msg, ns_bvci);
		}

		/* else: SGSN -> BSS direction */
		if (!peer) {
			LOGP(DGPRS, LOGL_INFO, "Didn't find peer for "
			     "BVCI=%u for message from NSVC=%u/NSEI=%u (SGSN)\n",
			     ns_bvci, nsvci, nsei);
			rate_ctr_inc(&get_global_ctrg()->
				     ctr[GBPROX_GLOB_CTR_INV_BVCI]);
			return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI,
					       &ns_bvci, msg);
		}
		if (peer->blocked) {
			LOGP(DGPRS, LOGL_NOTICE, "Dropping PDU for "
			     "blocked BVCI=%u via NSVC=%u/NSEI=%u\n",
			     ns_bvci, nsvci, nsei);
			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_DROPPED]);
			return bssgp_tx_status(BSSGP_CAUSE_BVCI_BLOCKED, NULL, msg);
		}
		rc = gbprox_relay2peer(msg, peer, ns_bvci);
	}

	return rc;
}

int gbprox_reset_persistent_nsvcs(struct gprs_ns_inst *nsi)
{
	struct gprs_nsvc *nsvc;

	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
		if (!nsvc->persistent)
			continue;
		gprs_nsvc_reset(nsvc, NS_CAUSE_OM_INTERVENTION);
	}
	return 0;
}

/* Signal handler for signals from NS layer */
int gbprox_signal(unsigned int subsys, unsigned int signal,
		  void *handler_data, void *signal_data)
{
	struct ns_signal_data *nssd = signal_data;
	struct gprs_nsvc *nsvc = nssd->nsvc;
	struct gbprox_peer *peer;

	if (subsys != SS_L_NS)
		return 0;

	if (signal == S_NS_RESET && nsvc->nsei == gbcfg.nsip_sgsn_nsei) {
		/* We have received a NS-RESET from the NSEI and NSVC
		 * of the SGSN.  This might happen with SGSN that start
		 * their own NS-RESET procedure without waiting for our
		 * NS-RESET */
		nsvc->remote_end_is_sgsn = 1;
	}

	if (signal == S_NS_ALIVE_EXP && nsvc->remote_end_is_sgsn) {
		LOGP(DGPRS, LOGL_NOTICE, "Tns alive expired too often, "
			"re-starting RESET procedure\n");
		rate_ctr_inc(&get_global_ctrg()->
			     ctr[GBPROX_GLOB_CTR_RESTART_RESET_SGSN]);
		gprs_ns_nsip_connect(nsvc->nsi, &nsvc->ip.bts_addr,
				  nsvc->nsei, nsvc->nsvci);
	}

	if (!nsvc->remote_end_is_sgsn) {
		/* from BSS to SGSN */
		peer = peer_by_nsei(nsvc->nsei);
		if (!peer) {
			LOGP(DGPRS, LOGL_NOTICE, "signal %u for unknown peer "
			     "NSEI=%u/NSVCI=%u\n", signal, nsvc->nsei,
			     nsvc->nsvci);
			return 0;
		}
		switch (signal) {
		case S_NS_RESET:
		case S_NS_BLOCK:
			if (!peer->blocked)
				break;
			LOGP(DGPRS, LOGL_NOTICE, "Converting NS_RESET from "
			     "NSEI=%u/NSVCI=%u into BSSGP_BVC_BLOCK to SGSN\n",
			     nsvc->nsei, nsvc->nsvci);
			bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_BLOCK, nsvc->nsei,
					     peer->bvci, 0);
			break;
		}
	} else {
		/* Forward this message to all NS-VC to BSS */
		struct gprs_ns_inst *nsi = gbcfg.nsi;
		struct gprs_nsvc *next_nsvc;

		llist_for_each_entry(next_nsvc, &nsi->gprs_nsvcs, list) {
			if (next_nsvc->remote_end_is_sgsn)
				continue;

			/* Note that the following does not start the full
			 * procedures including timer based retransmissions. */
			switch (signal) {
			case S_NS_RESET:
				gprs_ns_tx_reset(next_nsvc, nssd->cause);
				break;
			case S_NS_BLOCK:
				gprs_ns_tx_block(next_nsvc, nssd->cause);
				break;
			case S_NS_UNBLOCK:
				gprs_ns_tx_unblock(next_nsvc);
				break;
			}
		}
	}
	return 0;
}

int gbprox_dump_global(FILE *stream, int indent, int verbose)
{
	unsigned int i;
	const struct rate_ctr_group_desc *desc;
	int rc;

	rc = fprintf(stream, "%*sGbproxy global:\n", indent, "");
	if (rc < 0)
		return rc;

	if (!verbose)
		return 0;

	desc = get_global_ctrg()->desc;

	for (i = 0; i < desc->num_ctr; i++) {
		struct rate_ctr *ctr = &get_global_ctrg()->ctr[i];
		if (ctr->current) {
			rc = fprintf(stream, "%*s    %s: %llu\n",
				     indent, "",
				     desc->ctr_desc[i].description,
				     (long long)ctr->current);

			if (rc < 0)
				return rc;
		}
	}

	return 0;
}

int gbprox_dump_peers(FILE *stream, int indent, int verbose)
{
	struct gbprox_peer *peer;
	struct gprs_ra_id raid;
	unsigned int i;
	const struct rate_ctr_group_desc *desc;
	int rc;

	rc = fprintf(stream, "%*sPeers:\n", indent, "");
	if (rc < 0)
		return rc;

	llist_for_each_entry(peer, &gbprox_bts_peers, list) {
		gsm48_parse_ra(&raid, peer->ra);

		rc = fprintf(stream, "%*s  NSEI %u, BVCI %u, %sblocked, "
			     "RAC %u-%u-%u-%u\n",
			     indent, "",
			     peer->nsei, peer->bvci,
			     peer->blocked ? "" : "not ",
			     raid.mcc, raid.mnc, raid.lac, raid.rac);

		if (rc < 0)
			return rc;

		if (!verbose)
			continue;

		desc = peer->ctrg->desc;

		for (i = 0; i < desc->num_ctr; i++) {
			struct rate_ctr *ctr = &peer->ctrg->ctr[i];
			if (ctr->current) {
				rc = fprintf(stream, "%*s    %s: %llu\n",
					     indent, "",
					     desc->ctr_desc[i].description,
					     (long long)ctr->current);

				if (rc < 0)
					return rc;
			}
		}
	}

	return 0;
}

#include <osmocom/vty/command.h>

gDEFUN(show_gbproxy, show_gbproxy_cmd, "show gbproxy [stats]",
       SHOW_STR "Display information about the Gb proxy")
{
	struct gbprox_peer *peer;
	int show_stats = argc >= 1;

	if (show_stats)
		vty_out_rate_ctr_group(vty, "", get_global_ctrg());

	llist_for_each_entry(peer, &gbprox_bts_peers, list) {
		struct gprs_ra_id raid;
		gsm48_parse_ra(&raid, peer->ra);

		vty_out(vty, "NSEI %5u, PTP-BVCI %5u, "
			"RAC %u-%u-%u-%u",
			peer->nsei, peer->bvci,
			raid.mcc, raid.mnc, raid.lac, raid.rac);
		if (peer->blocked)
			vty_out(vty, " [BVC-BLOCKED]");

		vty_out(vty, "%s", VTY_NEWLINE);

		if (show_stats)
			vty_out_rate_ctr_group(vty, "  ", peer->ctrg);
	}
	return CMD_SUCCESS;
}

gDEFUN(delete_gb, delete_gb_cmd,
	"delete-gbproxy-peer <0-65534> bvci <0-65534>",
	"Delete a GBProxy peer by NSEI and BVCI\n"
	"NSEI number\n"
	"BVCI\n"
	"BVCI number\n")
{
	struct gbprox_peer *peer, *tmp;
	const uint16_t nsei = atoi(argv[0]);
	const uint16_t bvci = atoi(argv[1]);

	llist_for_each_entry_safe(peer, tmp, &gbprox_bts_peers, list) {
		if (peer->bvci != bvci)
			continue;
		if (peer->nsei != nsei)
			continue;

		peer_free(peer);
	}

	return CMD_SUCCESS;
}