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, 1226 insertions, 0 deletions

diff --git a/src/ipaccess/ipaccess-proxy.c b/src/ipaccess/ipaccess-proxy.c
new file mode 100644
index 000000000..d3674426c
--- /dev/null
+++ b/src/ipaccess/ipaccess-proxy.c
@@ -0,0 +1,1226 @@
+/* OpenBSC Abis/IP proxy ip.access nanoBTS */
+
+/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by On-Waves
+ * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.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 <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <signal.h>
+#include <time.h>
+#include <sys/fcntl.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#define _GNU_SOURCE
+#include <getopt.h>
+
+#include <openbsc/gsm_data.h>
+#include <osmocom/core/application.h>
+#include <osmocom/core/select.h>
+#include <osmocom/gsm/tlv.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/gsm/ipa.h>
+#include <osmocom/abis/ipa.h>
+#include <osmocom/abis/ipaccess.h>
+#include <openbsc/debug.h>
+#include <openbsc/ipaccess.h>
+#include <openbsc/socket.h>
+#include <osmocom/core/talloc.h>
+
+/* one instance of an ip.access protocol proxy */
+struct ipa_proxy {
+	/* socket where we listen for incoming OML from BTS */
+	struct osmo_fd oml_listen_fd;
+	/* socket where we listen for incoming RSL from BTS */
+	struct osmo_fd rsl_listen_fd;
+	/* list of BTS's (struct ipa_bts_conn */
+	struct llist_head bts_list;
+	/* the BSC reconnect timer */
+	struct osmo_timer_list reconn_timer;
+	/* global GPRS NS data */
+	struct in_addr gprs_addr;
+	struct in_addr listen_addr;
+};
+
+/* global pointer to the proxy structure */
+static struct ipa_proxy *ipp;
+
+struct ipa_proxy_conn {
+	struct osmo_fd fd;
+	struct llist_head tx_queue;
+	struct ipa_bts_conn *bts_conn;
+};
+#define MAX_TRX 4
+
+/* represents a particular BTS in our proxy */
+struct ipa_bts_conn {
+	/* list of BTS's (ipa_proxy->bts_list) */
+	struct llist_head list;
+	/* back pointer to the proxy which we belong to */
+	struct ipa_proxy *ipp;
+	/* the unit ID as determined by CCM */
+	struct {
+		uint16_t site_id;
+		uint16_t bts_id;
+	} unit_id;
+
+	/* incoming connections from BTS */
+	struct ipa_proxy_conn *oml_conn;
+	struct ipa_proxy_conn *rsl_conn[MAX_TRX];
+
+	/* outgoing connections to BSC */
+	struct ipa_proxy_conn *bsc_oml_conn;
+	struct ipa_proxy_conn *bsc_rsl_conn[MAX_TRX];
+
+	/* UDP sockets for BTS and BSC injection */
+	struct osmo_fd udp_bts_fd;
+	struct osmo_fd udp_bsc_fd;
+
+	/* NS data */
+	struct in_addr bts_addr;
+	struct osmo_fd gprs_ns_fd;
+	int gprs_local_port;
+	uint16_t gprs_orig_port;
+	uint32_t gprs_orig_ip;
+
+	char *id_tags[256];
+	uint8_t *id_resp;
+	unsigned int id_resp_len;
+};
+
+enum ipp_fd_type {
+	OML_FROM_BTS = 1,
+	RSL_FROM_BTS = 2,
+	OML_TO_BSC = 3,
+	RSL_TO_BSC = 4,
+	UDP_TO_BTS = 5,
+	UDP_TO_BSC = 6,
+};
+
+/* some of the code against we link from OpenBSC needs this */
+void *tall_bsc_ctx;
+
+static char *listen_ipaddr;
+static char *bsc_ipaddr;
+static char *gprs_ns_ipaddr;
+
+static int gprs_ns_cb(struct osmo_fd *bfd, unsigned int what);
+
+#define PROXY_ALLOC_SIZE	1200
+
+static struct ipa_bts_conn *find_bts_by_unitid(struct ipa_proxy *ipp,
+						uint16_t site_id,
+						uint16_t bts_id)
+{
+	struct ipa_bts_conn *ipbc;
+
+	llist_for_each_entry(ipbc, &ipp->bts_list, list) {
+		if (ipbc->unit_id.site_id == site_id &&
+		    ipbc->unit_id.bts_id == bts_id)
+			return ipbc;
+	}
+
+	return NULL;
+}
+
+struct ipa_proxy_conn *alloc_conn(void)
+{
+	struct ipa_proxy_conn *ipc;
+
+	ipc = talloc_zero(tall_bsc_ctx, struct ipa_proxy_conn);
+	if (!ipc)
+		return NULL;
+
+	INIT_LLIST_HEAD(&ipc->tx_queue);
+
+	return ipc;
+}
+
+static int store_idtags(struct ipa_bts_conn *ipbc, struct tlv_parsed *tlvp)
+{
+	unsigned int i, len;
+
+	for (i = 0; i <= 0xff; i++) {
+		if (!TLVP_PRESENT(tlvp, i))
+			continue;
+
+		len = TLVP_LEN(tlvp, i);
+#if 0
+		if (!ipbc->id_tags[i])
+			ipbc->id_tags[i] = talloc_size(tall_bsc_ctx, len);
+		else
+#endif
+			ipbc->id_tags[i] = talloc_realloc_size(ipbc,
+							  ipbc->id_tags[i], len);
+		if (!ipbc->id_tags[i])
+			return -ENOMEM;
+
+		memset(ipbc->id_tags[i], 0, len);
+		//memcpy(ipbc->id_tags[i], TLVP_VAL(tlvp, i), len);
+	}
+	return 0;
+}
+
+
+static struct ipa_proxy_conn *connect_bsc(struct sockaddr_in *sa, int priv_nr, void *data);
+
+#define logp_ipbc_uid(ss, lvl, ipbc, trx_id) _logp_ipbc_uid(ss, lvl, __FILE__, __LINE__, ipbc, trx_id)
+
+static void _logp_ipbc_uid(unsigned int ss, unsigned int lvl, char *file, int line,
+			   struct ipa_bts_conn *ipbc, uint8_t trx_id)
+{
+	if (ipbc)
+		logp2(ss, lvl, file, line, 0, "(%u/%u/%u) ", ipbc->unit_id.site_id,
+		     ipbc->unit_id.bts_id, trx_id);
+	else
+		logp2(ss, lvl, file, line, 0, "unknown ");
+}
+
+static int handle_udp_read(struct osmo_fd *bfd)
+{
+	struct ipa_bts_conn *ipbc = bfd->data;
+	struct ipa_proxy_conn *other_conn = NULL;
+	struct msgb *msg = msgb_alloc(PROXY_ALLOC_SIZE, "Abis/IP UDP");
+	struct ipaccess_head *hh;
+	int ret;
+
+	/* with UDP sockets, we cannot read partial packets but have to read
+	 * all of it in one go */
+	hh = (struct ipaccess_head *) msg->data;
+	ret = recv(bfd->fd, msg->data, msg->data_len, 0);
+	if (ret < 0) {
+		if (errno != EAGAIN)
+			LOGP(DLINP, LOGL_ERROR, "recv error  %s\n", strerror(errno));
+		msgb_free(msg);
+		return ret;
+	}
+	if (ret == 0) {
+		DEBUGP(DLINP, "UDP peer disappeared, dead socket\n");
+		osmo_fd_unregister(bfd);
+		close(bfd->fd);
+		bfd->fd = -1;
+		msgb_free(msg);
+		return -EIO;
+	}
+	if (ret < sizeof(*hh)) {
+		DEBUGP(DLINP, "could not even read header!?!\n");
+		msgb_free(msg);
+		return -EIO;
+	}
+	msgb_put(msg, ret);
+	msg->l2h = msg->data + sizeof(*hh);
+	DEBUGP(DLMI, "UDP RX: %s\n", osmo_hexdump(msg->data, msg->len));
+
+	if (hh->len != msg->len - sizeof(*hh)) {
+		DEBUGP(DLINP, "length (%u/%u) disagrees with header(%u)\n",
+			msg->len, msg->len - 3, hh->len);
+		msgb_free(msg);
+		return -EIO;
+	}
+
+	switch (bfd->priv_nr & 0xff) {
+	case UDP_TO_BTS:
+		/* injection towards BTS */
+		switch (hh->proto) {
+		case IPAC_PROTO_RSL:
+			/* FIXME: what to do about TRX > 0 */
+			other_conn = ipbc->rsl_conn[0];
+			break;
+		default:
+			DEBUGP(DLINP, "Unknown protocol 0x%02x, sending to "
+				"OML FD\n", hh->proto);
+			/* fall through */
+		case IPAC_PROTO_IPACCESS:
+		case IPAC_PROTO_OML:
+			other_conn = ipbc->oml_conn;
+			break;
+		}
+		break;
+	case UDP_TO_BSC:
+		/* injection towards BSC */
+		switch (hh->proto) {
+		case IPAC_PROTO_RSL:
+			/* FIXME: what to do about TRX > 0 */
+			other_conn = ipbc->bsc_rsl_conn[0];
+			break;
+		default:
+			DEBUGP(DLINP, "Unknown protocol 0x%02x, sending to "
+				"OML FD\n", hh->proto);
+			/* fall through */
+		case IPAC_PROTO_IPACCESS:
+		case IPAC_PROTO_OML:
+			other_conn = ipbc->bsc_oml_conn;
+			break;
+		}
+		break;
+	default:
+		DEBUGP(DLINP, "Unknown filedescriptor priv_nr=%04x\n", bfd->priv_nr);
+		break;
+	}
+
+	if (other_conn) {
+		/* enqueue the message for TX on the respective FD */
+		msgb_enqueue(&other_conn->tx_queue, msg);
+		other_conn->fd.when |= BSC_FD_WRITE;
+	} else
+		msgb_free(msg);
+
+	return 0;
+}
+
+static int handle_udp_write(struct osmo_fd *bfd)
+{
+	/* not implemented yet */
+	bfd->when &= ~BSC_FD_WRITE;
+
+	return -EIO;
+}
+
+/* callback from select.c in case one of the fd's can be read/written */
+static int udp_fd_cb(struct osmo_fd *bfd, unsigned int what)
+{
+	int rc = 0;
+
+	if (what & BSC_FD_READ)
+		rc = handle_udp_read(bfd);
+	if (what & BSC_FD_WRITE)
+		rc = handle_udp_write(bfd);
+
+	return rc;
+}
+
+
+static int ipbc_alloc_connect(struct ipa_proxy_conn *ipc, struct osmo_fd *bfd,
+			      uint16_t site_id, uint16_t bts_id,
+			      uint16_t trx_id, struct tlv_parsed *tlvp,
+			      struct msgb *msg)
+{
+	struct ipa_bts_conn *ipbc;
+	uint16_t udp_port;
+	int ret = 0;
+	struct sockaddr_in sin;
+
+	memset(&sin, 0, sizeof(sin));
+	sin.sin_family = AF_INET;
+	inet_aton(bsc_ipaddr, &sin.sin_addr);
+
+	DEBUGP(DLINP, "(%u/%u/%u) New BTS connection: ",
+		site_id, bts_id, trx_id);
+
+	/* OML needs to be established before RSL */
+	if ((bfd->priv_nr & 0xff) != OML_FROM_BTS) {
+		DEBUGPC(DLINP, "Not a OML connection ?!?\n");
+		return -EIO;
+	}
+
+	/* allocate new BTS connection data structure */
+	ipbc = talloc_zero(tall_bsc_ctx, struct ipa_bts_conn);
+	if (!ipbc) {
+		ret = -ENOMEM;
+		goto err_out;
+	}
+
+	DEBUGPC(DLINP, "Created BTS Conn data structure\n");
+	ipbc->ipp = ipp;
+	ipbc->unit_id.site_id = site_id;
+	ipbc->unit_id.bts_id = bts_id;
+	ipbc->oml_conn = ipc;
+	ipc->bts_conn = ipbc;
+
+	/* store the content of the ID TAGS for later reference */
+	store_idtags(ipbc, tlvp);
+	ipbc->id_resp_len = msg->len;
+	ipbc->id_resp = talloc_size(tall_bsc_ctx, ipbc->id_resp_len);
+	memcpy(ipbc->id_resp, msg->data, ipbc->id_resp_len);
+
+	/* Create OML TCP connection towards BSC */
+	sin.sin_port = htons(IPA_TCP_PORT_OML);
+	ipbc->bsc_oml_conn = connect_bsc(&sin, OML_TO_BSC, ipbc);
+	if (!ipbc->bsc_oml_conn) {
+		ret = -EIO;
+		goto err_bsc_conn;
+	}
+
+	DEBUGP(DLINP, "(%u/%u/%u) OML Connected to BSC\n",
+		site_id, bts_id, trx_id);
+
+	/* Create UDP socket for BTS packet injection */
+	udp_port = 10000 + (site_id % 1000)*100 + (bts_id % 100);
+	ret = make_sock(&ipbc->udp_bts_fd, IPPROTO_UDP, INADDR_ANY, udp_port,
+			UDP_TO_BTS, udp_fd_cb, ipbc);
+	if (ret < 0)
+		goto err_udp_bts;
+	DEBUGP(DLINP, "(%u/%u/%u) Created UDP socket for injection "
+		"towards BTS at port %u\n", site_id, bts_id, trx_id, udp_port);
+
+	/* Create UDP socket for BSC packet injection */
+	udp_port = 20000 + (site_id % 1000)*100 + (bts_id % 100);
+	ret = make_sock(&ipbc->udp_bsc_fd, IPPROTO_UDP, INADDR_ANY, udp_port,
+			UDP_TO_BSC, udp_fd_cb, ipbc);
+	if (ret < 0)
+		goto err_udp_bsc;
+	DEBUGP(DLINP, "(%u/%u/%u) Created UDP socket for injection "
+		"towards BSC at port %u\n", site_id, bts_id, trx_id, udp_port);
+
+
+	/* GPRS NS related code */
+	if (gprs_ns_ipaddr) {
+		struct sockaddr_in sock;
+		socklen_t len = sizeof(sock);
+		struct in_addr addr;
+		uint32_t ip;
+
+		inet_aton(listen_ipaddr, &addr);
+		ip = ntohl(addr.s_addr); /* make_sock() needs host byte order */
+		ret = make_sock(&ipbc->gprs_ns_fd, IPPROTO_UDP, ip, 0, 0,
+				gprs_ns_cb, ipbc);
+		if (ret < 0) {
+			LOGP(DLINP, LOGL_ERROR, "Creating the GPRS socket failed.\n");
+			goto err_udp_bsc;
+		}
+
+		ret = getsockname(ipbc->gprs_ns_fd.fd, (struct sockaddr* ) &sock, &len);
+		ipbc->gprs_local_port = ntohs(sock.sin_port);
+		LOGP(DLINP, LOGL_NOTICE,
+			"Created GPRS NS Socket. Listening on: %s:%d\n",
+			inet_ntoa(sock.sin_addr), ipbc->gprs_local_port);
+
+		ret = getpeername(bfd->fd, (struct sockaddr* ) &sock, &len);
+		ipbc->bts_addr = sock.sin_addr;
+	}
+
+	llist_add(&ipbc->list, &ipp->bts_list);
+
+	return 0;
+
+err_udp_bsc:
+	osmo_fd_unregister(&ipbc->udp_bts_fd);
+err_udp_bts:
+	osmo_fd_unregister(&ipbc->bsc_oml_conn->fd);
+	close(ipbc->bsc_oml_conn->fd.fd);
+	talloc_free(ipbc->bsc_oml_conn);
+	ipbc->bsc_oml_conn = NULL;
+err_bsc_conn:
+	talloc_free(ipbc->id_resp);
+	talloc_free(ipbc);
+#if 0
+	osmo_fd_unregister(bfd);
+	close(bfd->fd);
+	talloc_free(bfd);
+#endif
+err_out:
+	return ret;
+}
+
+static int ipaccess_rcvmsg(struct ipa_proxy_conn *ipc, struct msgb *msg,
+			   struct osmo_fd *bfd)
+{
+	struct tlv_parsed tlvp;
+	uint8_t msg_type = *(msg->l2h);
+	struct ipaccess_unit unit_data;
+	struct ipa_bts_conn *ipbc;
+	int ret = 0;
+
+	switch (msg_type) {
+	case IPAC_MSGT_PING:
+		ret = ipa_ccm_send_pong(bfd->fd);
+		break;
+	case IPAC_MSGT_PONG:
+		DEBUGP(DLMI, "PONG!\n");
+		break;
+	case IPAC_MSGT_ID_RESP:
+		DEBUGP(DLMI, "ID_RESP ");
+		/* parse tags, search for Unit ID */
+		ipa_ccm_idtag_parse(&tlvp, (uint8_t *)msg->l2h + 2,
+				     msgb_l2len(msg)-2);
+		DEBUGP(DLMI, "\n");
+
+		if (!TLVP_PRESENT(&tlvp, IPAC_IDTAG_UNIT)) {
+			LOGP(DLINP, LOGL_ERROR, "No Unit ID in ID RESPONSE !?!\n");
+			return -EIO;
+		}
+
+		/* lookup BTS, create sign_link, ... */
+		memset(&unit_data, 0, sizeof(unit_data));
+		ipa_parse_unitid((char *)TLVP_VAL(&tlvp, IPAC_IDTAG_UNIT),
+				      &unit_data);
+		ipbc = find_bts_by_unitid(ipp, unit_data.site_id, unit_data.bts_id);
+		if (!ipbc) {
+			/* We have not found an ipbc (per-bts proxy instance)
+			 * for this BTS yet.  The first connection of a new BTS must
+			 * be a OML connection.  We allocate the associated data structures,
+			 * and try to connect to the remote end */
+
+			return ipbc_alloc_connect(ipc, bfd, unit_data.site_id,
+						  unit_data.bts_id,
+						  unit_data.trx_id, &tlvp, msg);
+			/* if this fails, the caller will clean up bfd */
+		} else {
+			struct sockaddr_in sin;
+			memset(&sin, 0, sizeof(sin));
+			sin.sin_family = AF_INET;
+			inet_aton(bsc_ipaddr, &sin.sin_addr);
+
+			DEBUGP(DLINP, "Identified BTS %u/%u/%u\n",
+				unit_data.site_id, unit_data.bts_id, unit_data.trx_id);
+
+			if ((bfd->priv_nr & 0xff) != RSL_FROM_BTS) {
+				LOGP(DLINP, LOGL_ERROR, "Second OML connection from "
+				     "same BTS ?!?\n");
+				return 0;
+			}
+
+			if (unit_data.trx_id >= MAX_TRX) {
+				LOGP(DLINP, LOGL_ERROR, "We don't support more "
+				     "than %u TRX\n", MAX_TRX);
+				return -EINVAL;
+			}
+
+			ipc->bts_conn = ipbc;
+			/* store TRX number in higher 8 bit of the bfd private number */
+			bfd->priv_nr |= unit_data.trx_id << 8;
+			ipbc->rsl_conn[unit_data.trx_id] = ipc;
+
+			/* Create RSL TCP connection towards BSC */
+			sin.sin_port = htons(IPA_TCP_PORT_RSL);
+			ipbc->bsc_rsl_conn[unit_data.trx_id] =
+				connect_bsc(&sin, RSL_TO_BSC | (unit_data.trx_id << 8), ipbc);
+			if (!ipbc->bsc_oml_conn)
+				return -EIO;
+			DEBUGP(DLINP, "(%u/%u/%u) Connected RSL to BSC\n",
+				unit_data.site_id, unit_data.bts_id, unit_data.trx_id);
+		}
+		break;
+	case IPAC_MSGT_ID_GET:
+		DEBUGP(DLMI, "ID_GET\n");
+		if ((bfd->priv_nr & 0xff) != OML_TO_BSC &&
+		    (bfd->priv_nr & 0xff) != RSL_TO_BSC) {
+			DEBUGP(DLINP, "IDentity REQuest from BTS ?!?\n");
+			return -EIO;
+		}
+		ipbc = ipc->bts_conn;
+		if (!ipbc) {
+			DEBUGP(DLINP, "ID_GET from BSC before we have ID_RESP from BTS\n");
+			return -EIO;
+		}
+		ret = write(bfd->fd, ipbc->id_resp, ipbc->id_resp_len);
+		if (ret != ipbc->id_resp_len) {
+			LOGP(DLINP, LOGL_ERROR, "Partial write: %d of %d\n",
+			     ret, ipbc->id_resp_len);
+			return -EIO;
+		}
+		ret = 0;
+		break;
+	case IPAC_MSGT_ID_ACK:
+		DEBUGP(DLMI, "ID_ACK? -> ACK!\n");
+		ret = ipa_ccm_send_id_ack(bfd->fd);
+		break;
+	default:
+		LOGP(DLMI, LOGL_ERROR, "Unhandled IPA type; %d\n", msg_type);
+		return 1;
+		break;
+	}
+	return ret;
+}
+
+struct msgb *ipaccess_proxy_read_msg(struct osmo_fd *bfd, int *error)
+{
+	struct msgb *msg = msgb_alloc(PROXY_ALLOC_SIZE, "Abis/IP");
+	struct ipaccess_head *hh;
+	int len, ret = 0;
+
+	if (!msg) {
+		*error = -ENOMEM;
+		return NULL;
+	}
+
+	/* first read our 3-byte header */
+	hh = (struct ipaccess_head *) msg->data;
+	ret = recv(bfd->fd, msg->data, 3, 0);
+	if (ret < 0) {
+		if (errno != EAGAIN)
+			LOGP(DLINP, LOGL_ERROR, "recv error: %s\n", strerror(errno));
+		msgb_free(msg);
+		*error = ret;
+		return NULL;
+	} else if (ret == 0) {
+		msgb_free(msg);
+		*error = ret;
+		return NULL;
+	}
+
+	msgb_put(msg, ret);
+
+	/* then read te length as specified in header */
+	msg->l2h = msg->data + sizeof(*hh);
+	len = ntohs(hh->len);
+	ret = recv(bfd->fd, msg->l2h, len, 0);
+	if (ret < len) {
+		LOGP(DLINP, LOGL_ERROR, "short read!\n");
+		msgb_free(msg);
+		*error = -EIO;
+		return NULL;
+	}
+	msgb_put(msg, ret);
+
+	return msg;
+}
+
+static struct ipa_proxy_conn *ipc_by_priv_nr(struct ipa_bts_conn *ipbc,
+					     unsigned int priv_nr)
+{
+	struct ipa_proxy_conn *bsc_conn;
+	unsigned int trx_id = priv_nr >> 8;
+
+	switch (priv_nr & 0xff) {
+	case OML_FROM_BTS: /* incoming OML data from BTS, forward to BSC OML */
+		bsc_conn = ipbc->bsc_oml_conn;
+		break;
+	case RSL_FROM_BTS: /* incoming RSL data from BTS, forward to BSC RSL */
+		bsc_conn = ipbc->bsc_rsl_conn[trx_id];
+		break;
+	case OML_TO_BSC: /* incoming OML data from BSC, forward to BTS OML */
+		bsc_conn = ipbc->oml_conn;
+		break;
+	case RSL_TO_BSC: /* incoming RSL data from BSC, forward to BTS RSL */
+		bsc_conn = ipbc->rsl_conn[trx_id];
+		break;
+	default:
+		bsc_conn = NULL;
+		break;
+	}
+	return bsc_conn;
+}
+
+static void reconn_tmr_cb(void *data)
+{
+	struct ipa_proxy *ipp = data;
+	struct ipa_bts_conn *ipbc;
+	struct sockaddr_in sin;
+	int i;
+
+	DEBUGP(DLINP, "Running reconnect timer\n");
+
+	memset(&sin, 0, sizeof(sin));
+	sin.sin_family = AF_INET;
+	inet_aton(bsc_ipaddr, &sin.sin_addr);
+
+	llist_for_each_entry(ipbc, &ipp->bts_list, list) {
+		/* if OML to BSC is dead, try to restore it */
+		if (ipbc->oml_conn && !ipbc->bsc_oml_conn) {
+			sin.sin_port = htons(IPA_TCP_PORT_OML);
+			logp_ipbc_uid(DLINP, LOGL_NOTICE, ipbc, 0);
+			LOGPC(DLINP, LOGL_NOTICE, "OML Trying to reconnect\n");
+			ipbc->bsc_oml_conn = connect_bsc(&sin, OML_TO_BSC, ipbc);
+			if (!ipbc->bsc_oml_conn)
+				goto reschedule;
+			logp_ipbc_uid(DLINP, LOGL_NOTICE, ipbc, 0);
+			LOGPC(DLINP, LOGL_NOTICE, "OML Reconnected\n");
+		}
+		/* if we (still) don't have a OML connection, skip RSL */
+		if (!ipbc->oml_conn || !ipbc->bsc_oml_conn)
+			continue;
+
+		for (i = 0; i < ARRAY_SIZE(ipbc->rsl_conn); i++) {
+			unsigned int priv_nr;
+			/* don't establish RSL links which we don't have */
+			if (!ipbc->rsl_conn[i])
+				continue;
+			if (ipbc->bsc_rsl_conn[i])
+				continue;
+			priv_nr = ipbc->rsl_conn[i]->fd.priv_nr;
+			priv_nr &= ~0xff;
+			priv_nr |= RSL_TO_BSC;
+			sin.sin_port = htons(IPA_TCP_PORT_RSL);
+			logp_ipbc_uid(DLINP, LOGL_NOTICE, ipbc, priv_nr >> 8);
+			LOGPC(DLINP, LOGL_NOTICE, "RSL Trying to reconnect\n");
+			ipbc->bsc_rsl_conn[i] = connect_bsc(&sin, priv_nr, ipbc);
+			if (!ipbc->bsc_rsl_conn[i])
+				goto reschedule;
+			logp_ipbc_uid(DLINP, LOGL_NOTICE, ipbc, priv_nr >> 8);
+			LOGPC(DLINP, LOGL_NOTICE, "RSL Reconnected\n");
+		}
+	}
+	return;
+
+reschedule:
+	osmo_timer_schedule(&ipp->reconn_timer, 5, 0);
+}
+
+static void handle_dead_socket(struct osmo_fd *bfd)
+{
+	struct ipa_proxy_conn *ipc = bfd->data;		/* local conn */
+	struct ipa_proxy_conn *bsc_conn;		/* remote conn */
+	struct ipa_bts_conn *ipbc = ipc->bts_conn;
+	unsigned int trx_id = bfd->priv_nr >> 8;
+	struct msgb *msg, *msg2;
+
+	osmo_fd_unregister(bfd);
+	close(bfd->fd);
+	bfd->fd = -1;
+
+	/* FIXME: clear tx_queue, remove all references, etc. */
+	llist_for_each_entry_safe(msg, msg2, &ipc->tx_queue, list)
+		msgb_free(msg);
+
+	switch (bfd->priv_nr & 0xff) {
+	case OML_FROM_BTS: /* incoming OML data from BTS, forward to BSC OML */
+		/* The BTS started a connection with us but we got no
+		 * IPAC_MSGT_ID_RESP message yet, in that scenario we did not
+		 * allocate the ipa_bts_conn structure. */
+		if (ipbc == NULL)
+			break;
+		ipbc->oml_conn = NULL;
+		bsc_conn = ipbc->bsc_oml_conn;
+		/* close the connection to the BSC */
+		osmo_fd_unregister(&bsc_conn->fd);
+		close(bsc_conn->fd.fd);
+		llist_for_each_entry_safe(msg, msg2, &bsc_conn->tx_queue, list)
+			msgb_free(msg);
+		talloc_free(bsc_conn);
+		ipbc->bsc_oml_conn = NULL;
+		/* FIXME: do we need to delete the entire ipbc ? */
+		break;
+	case RSL_FROM_BTS: /* incoming RSL data from BTS, forward to BSC RSL */
+		ipbc->rsl_conn[trx_id] = NULL;
+		bsc_conn = ipbc->bsc_rsl_conn[trx_id];
+		/* close the connection to the BSC */
+		osmo_fd_unregister(&bsc_conn->fd);
+		close(bsc_conn->fd.fd);
+		llist_for_each_entry_safe(msg, msg2, &bsc_conn->tx_queue, list)
+			msgb_free(msg);
+		talloc_free(bsc_conn);
+		ipbc->bsc_rsl_conn[trx_id] = NULL;
+		break;
+	case OML_TO_BSC: /* incoming OML data from BSC, forward to BTS OML */
+		ipbc->bsc_oml_conn = NULL;
+		bsc_conn = ipbc->oml_conn;
+		/* start reconnect timer */
+		osmo_timer_schedule(&ipp->reconn_timer, 5, 0);
+		break;
+	case RSL_TO_BSC: /* incoming RSL data from BSC, forward to BTS RSL */
+		ipbc->bsc_rsl_conn[trx_id] = NULL;
+		bsc_conn = ipbc->rsl_conn[trx_id];
+		/* start reconnect timer */
+		osmo_timer_schedule(&ipp->reconn_timer, 5, 0);
+		break;
+	default:
+		bsc_conn = NULL;
+		break;
+	}
+
+	talloc_free(ipc);
+}
+
+static void patch_gprs_msg(struct ipa_bts_conn *ipbc, int priv_nr, struct msgb *msg)
+{
+	uint8_t *nsvci;
+
+	if ((priv_nr & 0xff) != OML_FROM_BTS && (priv_nr & 0xff) != OML_TO_BSC)
+		return;
+
+	if (msgb_l2len(msg) != 39)
+		return;
+
+	/*
+	 * Check if this is a IPA Set Attribute or IPA Set Attribute ACK
+	 * and if the FOM Class is GPRS NSVC0 and then we will patch it.
+	 *
+	 * The patch assumes the message looks like the one from the trace
+	 * but we only match messages with a specific size anyway... So
+	 * this hack should work just fine.
+	 */
+
+	if (msg->l2h[0] == 0x10 && msg->l2h[1] == 0x80 &&
+	    msg->l2h[2] == 0x00 && msg->l2h[3] == 0x15 &&
+	    msg->l2h[18] == 0xf5 && msg->l2h[19] == 0xf2) {
+		nsvci = &msg->l2h[23];
+		ipbc->gprs_orig_port =  *(uint16_t *)(nsvci+8);
+		ipbc->gprs_orig_ip = *(uint32_t *)(nsvci+10);
+		*(uint16_t *)(nsvci+8) = htons(ipbc->gprs_local_port);
+		*(uint32_t *)(nsvci+10) = ipbc->ipp->listen_addr.s_addr;
+	} else if (msg->l2h[0] == 0x10 && msg->l2h[1] == 0x80 &&
+	    msg->l2h[2] == 0x00 && msg->l2h[3] == 0x15 &&
+	    msg->l2h[18] == 0xf6 && msg->l2h[19] == 0xf2) {
+		nsvci = &msg->l2h[23];
+		*(uint16_t *)(nsvci+8) = ipbc->gprs_orig_port;
+		*(uint32_t *)(nsvci+10) = ipbc->gprs_orig_ip;
+	}
+}
+
+static int handle_tcp_read(struct osmo_fd *bfd)
+{
+	struct ipa_proxy_conn *ipc = bfd->data;
+	struct ipa_bts_conn *ipbc = ipc->bts_conn;
+	struct ipa_proxy_conn *bsc_conn;
+	struct msgb *msg;
+	struct ipaccess_head *hh;
+	int ret = 0;
+	char *btsbsc;
+
+	if ((bfd->priv_nr & 0xff) <= 2)
+		btsbsc = "BTS";
+	else
+		btsbsc = "BSC";
+
+	msg = ipaccess_proxy_read_msg(bfd, &ret);
+	if (!msg) {
+		if (ret == 0) {
+			logp_ipbc_uid(DLINP, LOGL_NOTICE, ipbc, bfd->priv_nr >> 8);
+			LOGPC(DLINP, LOGL_NOTICE, "%s disappeared, "
+			     "dead socket\n", btsbsc);
+			handle_dead_socket(bfd);
+		}
+		return ret;
+	}
+
+	msgb_put(msg, ret);
+	logp_ipbc_uid(DLMI, LOGL_DEBUG, ipbc, bfd->priv_nr >> 8);
+	DEBUGPC(DLMI, "RX<-%s: %s\n", btsbsc, osmo_hexdump(msg->data, msg->len));
+
+	hh = (struct ipaccess_head *) msg->data;
+	if (hh->proto == IPAC_PROTO_IPACCESS) {
+		ret = ipaccess_rcvmsg(ipc, msg, bfd);
+		if (ret < 0) {
+			osmo_fd_unregister(bfd);
+			close(bfd->fd);
+			bfd->fd = -1;
+			talloc_free(bfd);
+			msgb_free(msg);
+			return ret;
+		} else if (ret == 0) {
+			/* we do not forward parts of the CCM protocol
+			 * through the proxy but rather terminate it ourselves. */
+			msgb_free(msg);
+			return ret;
+		}
+	}
+
+	if (!ipbc) {
+		LOGP(DLINP, LOGL_ERROR,
+		     "received %s packet but no ipc->bts_conn?!?\n", btsbsc);
+		msgb_free(msg);
+		return -EIO;
+	}
+
+	bsc_conn = ipc_by_priv_nr(ipbc, bfd->priv_nr);
+	if (bsc_conn) {
+		if (gprs_ns_ipaddr)
+			patch_gprs_msg(ipbc, bfd->priv_nr, msg);
+		/* enqueue packet towards BSC */
+		msgb_enqueue(&bsc_conn->tx_queue, msg);
+		/* mark respective filedescriptor as 'we want to write' */
+		bsc_conn->fd.when |= BSC_FD_WRITE;
+	} else {
+		logp_ipbc_uid(DLINP, LOGL_INFO, ipbc, bfd->priv_nr >> 8);
+		LOGPC(DLINP, LOGL_INFO, "Dropping packet from %s, "
+		     "since remote connection is dead\n", btsbsc);
+		msgb_free(msg);
+	}
+
+	return ret;
+}
+
+/* a TCP socket is ready to be written to */
+static int handle_tcp_write(struct osmo_fd *bfd)
+{
+	struct ipa_proxy_conn *ipc = bfd->data;
+	struct ipa_bts_conn *ipbc = ipc->bts_conn;
+	struct llist_head *lh;
+	struct msgb *msg;
+	char *btsbsc;
+	int ret;
+
+	if ((bfd->priv_nr & 0xff) <= 2)
+		btsbsc = "BTS";
+	else
+		btsbsc = "BSC";
+
+
+	/* get the next msg for this timeslot */
+	if (llist_empty(&ipc->tx_queue)) {
+		bfd->when &= ~BSC_FD_WRITE;
+		return 0;
+	}
+	lh = ipc->tx_queue.next;
+	llist_del(lh);
+	msg = llist_entry(lh, struct msgb, list);
+
+	logp_ipbc_uid(DLMI, LOGL_DEBUG, ipbc, bfd->priv_nr >> 8);
+	DEBUGPC(DLMI, "TX %04x: %s\n", bfd->priv_nr,
+		osmo_hexdump(msg->data, msg->len));
+
+	ret = send(bfd->fd, msg->data, msg->len, 0);
+	msgb_free(msg);
+
+	if (ret == 0) {
+		logp_ipbc_uid(DLINP, LOGL_NOTICE, ipbc, bfd->priv_nr >> 8);
+		LOGP(DLINP, LOGL_NOTICE, "%s disappeared, dead socket\n", btsbsc);
+		handle_dead_socket(bfd);
+	}
+
+	return ret;
+}
+
+/* callback from select.c in case one of the fd's can be read/written */
+static int proxy_ipaccess_fd_cb(struct osmo_fd *bfd, unsigned int what)
+{
+	int rc = 0;
+
+	if (what & BSC_FD_READ) {
+		rc = handle_tcp_read(bfd);
+		if (rc < 0)
+			return rc;
+	}
+	if (what & BSC_FD_WRITE)
+		rc = handle_tcp_write(bfd);
+
+	return rc;
+}
+
+/* callback of the listening filedescriptor */
+static int listen_fd_cb(struct osmo_fd *listen_bfd, unsigned int what)
+{
+	int ret;
+	struct ipa_proxy_conn *ipc;
+	struct osmo_fd *bfd;
+	struct sockaddr_in sa;
+	socklen_t sa_len = sizeof(sa);
+
+	if (!(what & BSC_FD_READ))
+		return 0;
+
+	ret = accept(listen_bfd->fd, (struct sockaddr *) &sa, &sa_len);
+	if (ret < 0) {
+		perror("accept");
+		return ret;
+	}
+	DEBUGP(DLINP, "accept()ed new %s link from %s\n",
+		(listen_bfd->priv_nr & 0xff) == OML_FROM_BTS ? "OML" : "RSL",
+		inet_ntoa(sa.sin_addr));
+
+	ipc = alloc_conn();
+	if (!ipc) {
+		close(ret);
+		return -ENOMEM;
+	}
+
+	bfd = &ipc->fd;
+	bfd->fd = ret;
+	bfd->data = ipc;
+	bfd->priv_nr = listen_bfd->priv_nr;
+	bfd->cb = proxy_ipaccess_fd_cb;
+	bfd->when = BSC_FD_READ;
+	ret = osmo_fd_register(bfd);
+	if (ret < 0) {
+		LOGP(DLINP, LOGL_ERROR, "could not register FD\n");
+		close(bfd->fd);
+		talloc_free(ipc);
+		return ret;
+	}
+
+	/* Request ID. FIXME: request LOCATION, HW/SW VErsion, Unit Name, Serno */
+	ret = ipa_ccm_send_id_req(bfd->fd);
+
+	return 0;
+}
+
+static void send_ns(int fd, const char *buf, int size, struct in_addr ip, int port)
+{
+	int ret;
+	struct sockaddr_in addr;
+	socklen_t len = sizeof(addr);
+	memset(&addr, 0, sizeof(addr));
+
+	addr.sin_family = AF_INET;
+	addr.sin_port = htons(port);
+	addr.sin_addr = ip;
+
+	ret = sendto(fd, buf, size, 0, (struct sockaddr *) &addr, len);
+	if (ret < 0) {
+		LOGP(DLINP, LOGL_ERROR, "Failed to forward GPRS message.\n");
+	}
+}
+
+static int gprs_ns_cb(struct osmo_fd *bfd, unsigned int what)
+{
+	struct ipa_bts_conn *bts;
+	char buf[4096];
+	int ret;
+	struct sockaddr_in sock;
+	socklen_t len = sizeof(sock);
+
+	/* 1. get the data... */
+	ret = recvfrom(bfd->fd, buf, sizeof(buf), 0, (struct sockaddr *) &sock, &len);
+	if (ret < 0) {
+		LOGP(DLINP, LOGL_ERROR, "Failed to recv GPRS NS msg: %s.\n", strerror(errno));
+		return -1;
+	}
+
+	bts = bfd->data;
+
+	/* 2. figure out where to send it to */
+	if (memcmp(&sock.sin_addr, &ipp->gprs_addr, sizeof(sock.sin_addr)) == 0) {
+		LOGP(DLINP, LOGL_DEBUG, "GPRS NS msg from network.\n");
+		send_ns(bfd->fd, buf, ret, bts->bts_addr, 23000);
+	} else if (memcmp(&sock.sin_addr, &bts->bts_addr, sizeof(sock.sin_addr)) == 0) {
+		LOGP(DLINP, LOGL_DEBUG, "GPRS NS msg from BTS.\n");
+		send_ns(bfd->fd, buf, ret, ipp->gprs_addr, 23000);
+	} else {
+		LOGP(DLINP, LOGL_ERROR, "Unknown GPRS source: %s\n", inet_ntoa(sock.sin_addr));
+	}
+
+	return 0;
+}
+
+/* Actively connect to a BSC.  */
+static struct ipa_proxy_conn *connect_bsc(struct sockaddr_in *sa, int priv_nr, void *data)
+{
+	struct ipa_proxy_conn *ipc;
+	struct osmo_fd *bfd;
+	int ret, on = 1;
+
+	ipc = alloc_conn();
+	if (!ipc)
+		return NULL;
+
+	ipc->bts_conn = data;
+
+	bfd = &ipc->fd;
+	bfd->fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	bfd->cb = ipaccess_fd_cb;
+	bfd->when = BSC_FD_READ | BSC_FD_WRITE;
+	bfd->data = ipc;
+	bfd->priv_nr = priv_nr;
+
+	if (bfd->fd < 0) {
+		LOGP(DLINP, LOGL_ERROR, "Could not create socket: %s\n",
+			strerror(errno));
+		talloc_free(ipc);
+		return NULL;
+	}
+
+	ret = setsockopt(bfd->fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+	if (ret < 0) {
+		LOGP(DLINP, LOGL_ERROR, "Could not set socket option\n");
+		close(bfd->fd);
+		talloc_free(ipc);
+		return NULL;
+	}
+
+	ret = connect(bfd->fd, (struct sockaddr *) sa, sizeof(*sa));
+	if (ret < 0) {
+		LOGP(DLINP, LOGL_ERROR, "Could not connect socket: %s\n",
+		     inet_ntoa(sa->sin_addr));
+		close(bfd->fd);
+		talloc_free(ipc);
+		return NULL;
+	}
+
+	/* pre-fill tx_queue with identity request */
+	ret = osmo_fd_register(bfd);
+	if (ret < 0) {
+		close(bfd->fd);
+		talloc_free(ipc);
+		return NULL;
+	}
+
+	return ipc;
+}
+
+static int ipaccess_proxy_setup(void)
+{
+	int ret;
+
+	ipp = talloc_zero(tall_bsc_ctx, struct ipa_proxy);
+	if (!ipp)
+		return -ENOMEM;
+	INIT_LLIST_HEAD(&ipp->bts_list);
+	osmo_timer_setup(&ipp->reconn_timer, reconn_tmr_cb, ipp);
+
+	/* Listen for OML connections */
+	ret = make_sock(&ipp->oml_listen_fd, IPPROTO_TCP, INADDR_ANY,
+			IPA_TCP_PORT_OML, OML_FROM_BTS, listen_fd_cb, NULL);
+	if (ret < 0)
+		return ret;
+
+	/* Listen for RSL connections */
+	ret = make_sock(&ipp->rsl_listen_fd, IPPROTO_TCP, INADDR_ANY,
+			IPA_TCP_PORT_RSL, RSL_FROM_BTS, listen_fd_cb, NULL);
+
+	if (ret < 0)
+		return ret;
+
+	/* Connect the GPRS NS Socket */
+	if (gprs_ns_ipaddr) {
+		inet_aton(gprs_ns_ipaddr, &ipp->gprs_addr);
+		inet_aton(listen_ipaddr, &ipp->listen_addr);
+	}
+
+	return ret;
+}
+
+static void signal_handler(int signal)
+{
+	fprintf(stdout, "signal %u received\n", 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 print_help(void)
+{
+	printf(" ipaccess-proxy is a proxy BTS.\n");
+	printf(" -h --help. This help text.\n");
+	printf(" -l --listen IP. The ip to listen to.\n");
+	printf(" -b --bsc IP. The BSC IP address.\n");
+	printf(" -g --gprs IP. Take GPRS NS from that IP.\n");
+	printf("\n");
+	printf(" -s --disable-color. Disable the color inside the logging message.\n");
+	printf(" -e --log-level number. Set the global loglevel.\n");
+	printf(" -T --timestamp. Prefix every log message with a timestamp.\n");
+	printf(" -V --version. Print the version of OpenBSC.\n");
+}
+
+static void print_usage(void)
+{
+	printf("Usage: ipaccess-proxy [options]\n");
+}
+
+enum {
+	IPA_PROXY_OPT_LISTEN_NONE	= 0,
+	IPA_PROXY_OPT_LISTEN_IP		= (1 << 0),
+	IPA_PROXY_OPT_BSC_IP		= (1 << 1),
+};
+
+static void handle_options(int argc, char** argv)
+{
+	int options_mask = 0;
+
+	/* disable explicit missing arguments error output from getopt_long */
+	opterr = 0;
+
+	while (1) {
+		int option_index = 0, c;
+		static struct option long_options[] = {
+			{"help", 0, 0, 'h'},
+			{"disable-color", 0, 0, 's'},
+			{"timestamp", 0, 0, 'T'},
+			{"log-level", 1, 0, 'e'},
+			{"listen", 1, 0, 'l'},
+			{"bsc", 1, 0, 'b'},
+			{0, 0, 0, 0}
+		};
+
+		c = getopt_long(argc, argv, "hsTe:l:b:g:",
+				long_options, &option_index);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'h':
+			print_usage();
+			print_help();
+			exit(0);
+		case 'l':
+			listen_ipaddr = optarg;
+			options_mask |= IPA_PROXY_OPT_LISTEN_IP;
+			break;
+		case 'b':
+			bsc_ipaddr = optarg;
+			options_mask |= IPA_PROXY_OPT_BSC_IP;
+			break;
+		case 'g':
+			gprs_ns_ipaddr = optarg;
+			break;
+		case 's':
+			log_set_use_color(osmo_stderr_target, 0);
+			break;
+		case 'T':
+			log_set_print_timestamp(osmo_stderr_target, 1);
+			break;
+		case 'e':
+			log_set_log_level(osmo_stderr_target, atoi(optarg));
+			break;
+		case '?':
+			if (optopt) {
+				printf("ERROR: missing mandatory argument "
+				       "for `%s' option\n", argv[optind-1]);
+			} else {
+				printf("ERROR: unknown option `%s'\n",
+					argv[optind-1]);
+			}
+			print_usage();
+			print_help();
+			exit(EXIT_FAILURE);
+			break;
+		default:
+			/* ignore */
+			break;
+		}
+	}
+	if ((options_mask & (IPA_PROXY_OPT_LISTEN_IP | IPA_PROXY_OPT_BSC_IP))
+		 != (IPA_PROXY_OPT_LISTEN_IP | IPA_PROXY_OPT_BSC_IP)) {
+		printf("ERROR: You have to specify `--listen' and `--bsc' "
+		       "options at least.\n");
+		print_usage();
+		print_help();
+		exit(EXIT_FAILURE);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	int rc;
+
+	tall_bsc_ctx = talloc_named_const(NULL, 1, "ipaccess-proxy");
+	msgb_talloc_ctx_init(tall_bsc_ctx, 0);
+
+	osmo_init_logging(&log_info);
+	log_parse_category_mask(osmo_stderr_target, "DLINP:DLMI");
+
+	handle_options(argc, argv);
+
+	rc = ipaccess_proxy_setup();
+	if (rc < 0)
+		exit(1);
+
+	signal(SIGUSR1, &signal_handler);
+	signal(SIGABRT, &signal_handler);
+	osmo_init_ignore_signals();
+
+	while (1) {
+		osmo_select_main(0);
+	}
+}