/* OpenBSC Abis input driver for ip.access */

/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
 * (C) 2010 by Holger Hans Peter Freyther
 * (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 <unistd.h>
#include <stdint.h>
#include <errno.h>
#include <stdlib.h>

#include <arpa/inet.h>

#include <osmocom/core/msgb.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/macaddr.h>
#include <osmocom/core/select.h>

#include <osmocom/gsm/tlv.h>
#include <osmocom/gsm/protocol/ipaccess.h>
#include <osmocom/gsm/ipa.h>

#define IPA_ALLOC_SIZE 1200

/*
 * Common propietary IPA messages:
 *      - PONG: in reply to PING.
 *      - ID_REQUEST: first messages once OML has been established.
 *      - ID_ACK: in reply to ID_ACK.
 */
static const uint8_t ipa_pong_msg[] = {
	0, 1, IPAC_PROTO_IPACCESS, IPAC_MSGT_PONG
};

static const uint8_t ipa_id_ack_msg[] = {
	0, 1, IPAC_PROTO_IPACCESS, IPAC_MSGT_ID_ACK
};

static const uint8_t ipa_id_req_msg[] = {
	0, 17, IPAC_PROTO_IPACCESS, IPAC_MSGT_ID_GET,
	0x01, IPAC_IDTAG_UNIT,
	0x01, IPAC_IDTAG_MACADDR,
	0x01, IPAC_IDTAG_LOCATION1,
	0x01, IPAC_IDTAG_LOCATION2,
	0x01, IPAC_IDTAG_EQUIPVERS,
	0x01, IPAC_IDTAG_SWVERSION,
	0x01, IPAC_IDTAG_UNITNAME,
	0x01, IPAC_IDTAG_SERNR,
};


static const char *idtag_names[] = {
	[IPAC_IDTAG_SERNR]	= "Serial_Number",
	[IPAC_IDTAG_UNITNAME]	= "Unit_Name",
	[IPAC_IDTAG_LOCATION1]	= "Location_1",
	[IPAC_IDTAG_LOCATION2]	= "Location_2",
	[IPAC_IDTAG_EQUIPVERS]	= "Equipment_Version",
	[IPAC_IDTAG_SWVERSION]	= "Software_Version",
	[IPAC_IDTAG_IPADDR]	= "IP_Address",
	[IPAC_IDTAG_MACADDR]	= "MAC_Address",
	[IPAC_IDTAG_UNIT]	= "Unit_ID",
};

const char *ipa_ccm_idtag_name(uint8_t tag)
{
	if (tag >= ARRAY_SIZE(idtag_names))
		return "unknown";

	return idtag_names[tag];
}

int ipa_ccm_idtag_parse(struct tlv_parsed *dec, unsigned char *buf, int len)
{
	uint8_t t_len;
	uint8_t t_tag;
	uint8_t *cur = buf;

	memset(dec, 0, sizeof(*dec));

	while (len >= 2) {
		len -= 2;
		t_len = *cur++;
		t_tag = *cur++;

		if (t_len > len + 1) {
			LOGP(DLMI, LOGL_ERROR, "The tag does not fit: %d\n", t_len);
			return -EINVAL;
		}

		DEBUGPC(DLMI, "%s='%s' ", ipa_ccm_idtag_name(t_tag), cur);

		dec->lv[t_tag].len = t_len;
		dec->lv[t_tag].val = cur;

		cur += t_len;
		len -= t_len;
	}
	return 0;
}

int ipa_parse_unitid(const char *str, struct ipaccess_unit *unit_data)
{
	unsigned long ul;
	char *endptr;
	const char *nptr;

	nptr = str;
	ul = strtoul(nptr, &endptr, 10);
	if (endptr <= nptr)
		return -EINVAL;
	unit_data->site_id = ul & 0xffff;

	if (*endptr++ != '/')
		return -EINVAL;

	nptr = endptr;
	ul = strtoul(nptr, &endptr, 10);
	if (endptr <= nptr)
		return -EINVAL;
	unit_data->bts_id = ul & 0xffff;

	if (*endptr++ != '/')
		return -EINVAL;

	nptr = endptr;
	ul = strtoul(nptr, &endptr, 10);
	if (endptr <= nptr)
		return -EINVAL;
	unit_data->trx_id = ul & 0xffff;

	return 0;
}

int ipa_ccm_tlv_to_unitdata(struct ipaccess_unit *ud,
			     const struct tlv_parsed *tp)
{
	int rc = 0;

	if (TLVP_PRES_LEN(tp, IPAC_IDTAG_SERNR, 1))
		ud->serno = talloc_strdup(ud, (char *)
					TLVP_VAL(tp, IPAC_IDTAG_SERNR));

	if (TLVP_PRES_LEN(tp, IPAC_IDTAG_UNITNAME, 1))
		ud->unit_name = talloc_strdup(ud, (char *)
					TLVP_VAL(tp, IPAC_IDTAG_UNITNAME));

	if (TLVP_PRES_LEN(tp, IPAC_IDTAG_LOCATION1, 1))
		ud->location1 = talloc_strdup(ud, (char *)
					TLVP_VAL(tp, IPAC_IDTAG_LOCATION1));

	if (TLVP_PRES_LEN(tp, IPAC_IDTAG_LOCATION2, 1))
		ud->location2 = talloc_strdup(ud, (char *)
					TLVP_VAL(tp, IPAC_IDTAG_LOCATION2));

	if (TLVP_PRES_LEN(tp, IPAC_IDTAG_EQUIPVERS, 1))
		ud->equipvers = talloc_strdup(ud, (char *)
					TLVP_VAL(tp, IPAC_IDTAG_EQUIPVERS));

	if (TLVP_PRES_LEN(tp, IPAC_IDTAG_SWVERSION, 1))
		ud->swversion = talloc_strdup(ud, (char *)
					TLVP_VAL(tp, IPAC_IDTAG_SWVERSION));

	if (TLVP_PRES_LEN(tp, IPAC_IDTAG_MACADDR, 17)) {
		rc = osmo_macaddr_parse(ud->mac_addr, (char *)
					TLVP_VAL(tp, IPAC_IDTAG_MACADDR));
		if (rc < 0)
			goto out;
	}

	if (TLVP_PRES_LEN(tp, IPAC_IDTAG_UNIT, 1))
		rc = ipa_parse_unitid((char *)
					TLVP_VAL(tp, IPAC_IDTAG_UNIT), ud);

out:
	return rc;
}

int ipa_send(int fd, const void *msg, size_t msglen)
{
	int ret;

	ret = write(fd, msg, msglen);
	if (ret < 0)
		return ret;
	if (ret < msglen) {
		LOGP(DLINP, LOGL_ERROR, "ipa_send: short write\n");
		return -EIO;
	}
	return ret;
}

int ipa_ccm_send_pong(int fd)
{
	return ipa_send(fd, ipa_pong_msg, sizeof(ipa_pong_msg));
}

int ipa_ccm_send_id_ack(int fd)
{
	return ipa_send(fd, ipa_id_ack_msg, sizeof(ipa_id_ack_msg));
}

int ipa_ccm_send_id_req(int fd)
{
	return ipa_send(fd, ipa_id_req_msg, sizeof(ipa_id_req_msg));
}

/* base handling of the ip.access protocol */
int ipa_ccm_rcvmsg_base(struct msgb *msg, struct osmo_fd *bfd)
{
	uint8_t msg_type = *(msg->l2h);
	int ret;

	switch (msg_type) {
	case IPAC_MSGT_PING:
		ret = ipa_ccm_send_pong(bfd->fd);
		if (ret < 0) {
			LOGP(DLINP, LOGL_ERROR, "Cannot send PING "
			     "message. Reason: %s\n", strerror(errno));
			break;
		}
		ret = 1;
		break;
	case IPAC_MSGT_PONG:
		DEBUGP(DLMI, "PONG!\n");
		ret = 1;
		break;
	case IPAC_MSGT_ID_ACK:
		DEBUGP(DLMI, "ID_ACK? -> ACK!\n");
		ret = ipa_ccm_send_id_ack(bfd->fd);
		if (ret < 0) {
			LOGP(DLINP, LOGL_ERROR, "Cannot send ID_ACK "
			     "message. Reason: %s\n", strerror(errno));
			break;
		}
		ret = 1;
		break;
	default:
		/* This is not an IPA PING, PONG or ID_ACK message */
		ret = 0;
		break;
	}
	return ret;
}

/* base handling of the ip.access protocol */
int ipa_ccm_rcvmsg_bts_base(struct msgb *msg, struct osmo_fd *bfd)
{
	uint8_t msg_type = *(msg->l2h);
	int ret = 0;

	switch (msg_type) {
	case IPAC_MSGT_PING:
		ret = ipa_ccm_send_pong(bfd->fd);
		if (ret < 0) {
			LOGP(DLINP, LOGL_ERROR, "Cannot send PONG "
			     "message. Reason: %s\n", strerror(errno));
		}
		break;
	case IPAC_MSGT_PONG:
		DEBUGP(DLMI, "PONG!\n");
		break;
	case IPAC_MSGT_ID_ACK:
		DEBUGP(DLMI, "ID_ACK\n");
		break;
	}
	return ret;
}


void ipa_prepend_header_ext(struct msgb *msg, int proto)
{
	struct ipaccess_head_ext *hh_ext;

	/* prepend the osmo ip.access header extension */
	hh_ext = (struct ipaccess_head_ext *) msgb_push(msg, sizeof(*hh_ext));
	hh_ext->proto = proto;
}

void ipa_prepend_header(struct msgb *msg, int proto)
{
	struct ipaccess_head *hh;

	/* prepend the ip.access header */
	hh = (struct ipaccess_head *) msgb_push(msg, sizeof(*hh));
	hh->len = htons(msg->len - sizeof(*hh));
	hh->proto = proto;
}

int ipa_msg_recv(int fd, struct msgb **rmsg)
{
	int rc = ipa_msg_recv_buffered(fd, rmsg, NULL);
	if (rc < 0) {
		errno = -rc;
		rc = -1;
	}
	return rc;
}

int ipa_msg_recv_buffered(int fd, struct msgb **rmsg, struct msgb **tmp_msg)
{
	struct msgb *msg = tmp_msg ? *tmp_msg : NULL;
	struct ipaccess_head *hh;
	int len, ret;
	int needed;

	if (msg == NULL) {
		msg = ipa_msg_alloc(0);
		if (msg == NULL) {
			ret = -ENOMEM;
			goto discard_msg;
		}
		msg->l1h = msg->tail;
	}

	if (msg->l2h == NULL) {
		/* first read our 3-byte header */
		needed = sizeof(*hh) - msg->len;
		ret = recv(fd, msg->tail, needed, 0);
		if (ret == 0)
		       goto discard_msg;

		if (ret < 0) {
			if (errno == EAGAIN || errno == EINTR)
				ret = 0;
			else {
				ret = -errno;
				goto discard_msg;
			}
		}

		msgb_put(msg, ret);

		if (ret < needed) {
			if (msg->len == 0) {
				ret = -EAGAIN;
				goto discard_msg;
			}

			LOGP(DLINP, LOGL_INFO,
			     "Received part of IPA message header (%d/%zu)\n",
			     msg->len, sizeof(*hh));
			if (!tmp_msg) {
				ret = -EIO;
				goto discard_msg;
			}
			*tmp_msg = msg;
			return -EAGAIN;
		}

		msg->l2h = msg->tail;
	}

	hh = (struct ipaccess_head *) msg->data;

	/* then read the length as specified in header */
	len = ntohs(hh->len);

	if (len < 0 || IPA_ALLOC_SIZE < len + sizeof(*hh)) {
		LOGP(DLINP, LOGL_ERROR, "bad message length of %d bytes, "
					"received %d bytes\n", len, msg->len);
		ret = -EIO;
		goto discard_msg;
	}

	needed = len - msgb_l2len(msg);

	if (needed > 0) {
		ret = recv(fd, msg->tail, needed, 0);

		if (ret == 0)
			goto discard_msg;

		if (ret < 0) {
			if (errno == EAGAIN || errno == EINTR)
				ret = 0;
			else {
				ret = -errno;
				goto discard_msg;
			}
		}

		msgb_put(msg, ret);

		if (ret < needed) {
			LOGP(DLINP, LOGL_INFO,
			     "Received part of IPA message L2 data (%d/%d)\n",
			    msgb_l2len(msg), len);
			if (!tmp_msg) {
				ret = -EIO;
				goto discard_msg;
			}
			*tmp_msg = msg;
			return -EAGAIN;
		}
	}

	ret = msgb_l2len(msg);

	if (ret == 0) {
		LOGP(DLINP, LOGL_INFO,
		     "Discarding IPA message without payload\n");
		ret = -EAGAIN;
		goto discard_msg;
	}

	if (tmp_msg)
		*tmp_msg = NULL;
	*rmsg = msg;
	return ret;

discard_msg:
	if (tmp_msg)
		*tmp_msg = NULL;
	msgb_free(msg);
	return ret;
}

struct msgb *ipa_msg_alloc(int headroom)
{
	struct msgb *nmsg;

	headroom += sizeof(struct ipaccess_head);

	nmsg = msgb_alloc_headroom(1200 + headroom, headroom, "Abis/IP");
	if (!nmsg)
		return NULL;
	return nmsg;
}