/* Trunk handling */

/*
 * (C) 2009-2012 by Holger Hans Peter Freyther <zecke@selfish.org>
 * (C) 2009-2012 by On-Waves
 * (C) 2017-2020 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
 * 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 <osmocom/mgcp/mgcp_internal.h>
#include <osmocom/mgcp/mgcp_endp.h>
#include <osmocom/mgcp/mgcp_trunk.h>

/*! allocate trunk and add it (if required) to the trunk list
 *  (called once at startup by VTY)
 *  \param[in] cfg mgcp configuration
 *  \param[in] nr trunk number
 *  \param[in] ttype trunk type
 *  \returns pointer to allocated trunk, NULL on failure */
struct mgcp_trunk *mgcp_trunk_alloc(struct mgcp_config *cfg, enum mgcp_trunk_type ttype, int nr)
{
	struct mgcp_trunk *trunk;

	trunk = talloc_zero(cfg, struct mgcp_trunk);
	if (!trunk) {
		LOGP(DLMGCP, LOGL_ERROR, "Failed to allocate.\n");
		return NULL;
	}

	trunk->cfg = cfg;
	trunk->trunk_type = ttype;
	trunk->trunk_nr = nr;

	trunk->audio_send_ptime = 1;
	trunk->audio_send_name = 1;
	trunk->vty_number_endpoints = 33;
	trunk->omit_rtcp = 0;

	mgcp_trunk_set_keepalive(trunk, MGCP_KEEPALIVE_ONCE);

	/* Note: Trunk Nr.0 is reserved as "virtual trunk",
	 * it is not stored using a separate pointer and
	 * not in the trunk list. */
	if (nr > 0)
		llist_add_tail(&trunk->entry, &cfg->trunks);

        mgcp_ratectr_trunk_alloc(cfg, &trunk->ratectr);

	return trunk;
}

/*! allocate endpoints and set default values.
 *  (called once at startup by VTY)
 *  \param[in] trunk trunk configuration
 *  \returns 0 on success, -1 on failure */
int mgcp_trunk_alloc_endpts(struct mgcp_trunk *trunk)
{
	int i;
	char ep_name_buf[MGCP_ENDPOINT_MAXLEN];
	struct mgcp_endpoint *endp;

	/* Make sure the amount of requested endpoints does not execeed
	 * sane limits. The VTY already limits the possible amount,
	 * however miss-initalation of the struct or memory corruption
	 * could still lead to an excessive allocation of endpoints, so
	 * better stop early if that is the case. */
	OSMO_ASSERT(trunk->vty_number_endpoints < 65534);

	/* This function is called once on startup by the VTY to allocate the
	 * endpoints. The number of endpoints must not change througout the
	 * runtime of the MGW */
	OSMO_ASSERT(trunk->number_endpoints == 0);
	OSMO_ASSERT(trunk->endpoints == NULL);

	/* allocate pointer array for the endpoints */
	trunk->endpoints = _talloc_zero_array(trunk->cfg,
					     sizeof(struct mgcp_endpoint *), trunk->vty_number_endpoints, "endpoints");
	if (!trunk->endpoints)
		return -1;

	/* create endpoints */
	for (i = 0; i < trunk->vty_number_endpoints; ++i) {
		switch (trunk->trunk_type) {
		case MGCP_TRUNK_VIRTUAL:
			snprintf(ep_name_buf, sizeof(ep_name_buf), "%s%x@%s", MGCP_ENDPOINT_PREFIX_VIRTUAL_TRUNK, i,
				 trunk->cfg->domain);
			break;
		case MGCP_TRUNK_E1:
			/* FIXME: E1 trunk implementation is work in progress, this endpoint
			 * name is incomplete (subslots) */
			snprintf(ep_name_buf, sizeof(ep_name_buf), "%s-1/%x", MGCP_ENDPOINT_PREFIX_E1_TRUNK, i);
			break;
		default:
			osmo_panic("Cannot allocate unimplemented trunk type %d! %s:%d\n",
				   trunk->trunk_type, __FILE__, __LINE__);
		}

		endp = mgcp_endp_alloc(trunk, ep_name_buf);
		if (!endp) {
			talloc_free(trunk->endpoints);
			return -1;
		}
		trunk->endpoints[i] = endp;
	}

	/* make the endpoints we just created available to the MGW code */
	trunk->number_endpoints = trunk->vty_number_endpoints;

	return 0;
}

/*! get trunk configuration by trunk number (index).
 *  \param[in] cfg mgcp configuration
 *  \param[in] index trunk number
 *  \returns pointer to trunk configuration, NULL on error */
struct mgcp_trunk *mgcp_trunk_by_num(const struct mgcp_config *cfg, int index)
{
	struct mgcp_trunk *trunk;

	llist_for_each_entry(trunk, &cfg->trunks, entry)
	    if (trunk->trunk_nr == index)
		return trunk;

	return NULL;
}

/*! Find a trunk by the trunk prefix in the endpoint name.
 *  \param[in] epname endpoint name with trunk prefix to look up.
 *  \param[in] cfg that contains the trunks where the endpoint is located.
 *  \returns trunk or NULL if trunk was not found. */
struct mgcp_trunk *mgcp_trunk_by_name(const struct mgcp_config *cfg, const char *epname)
{
	size_t prefix_len;
	char epname_lc[MGCP_ENDPOINT_MAXLEN];

	osmo_str_tolower_buf(epname_lc, sizeof(epname_lc), epname);
	epname = epname_lc;

	prefix_len = sizeof(MGCP_ENDPOINT_PREFIX_VIRTUAL_TRUNK) - 1;
	if (strncmp(epname, MGCP_ENDPOINT_PREFIX_VIRTUAL_TRUNK, prefix_len) == 0) {
		return cfg->virt_trunk;
	}

	/* E1 trunks are not implemented yet, so we deny any request for an
	 * e1 trunk for now. */
	prefix_len = sizeof(MGCP_ENDPOINT_PREFIX_E1_TRUNK) - 1;
	if (strncmp(epname, MGCP_ENDPOINT_PREFIX_E1_TRUNK, prefix_len) == 0) {
		LOGP(DLMGCP, LOGL_ERROR,
		     "endpoint name \"%s\" suggests an E1 trunk, but E1 trunks are not implemented in this version of osmo-mgw!\n", epname);
		return NULL;
	}

	/* Earlier versions of osmo-mgw were accepting endpoint names
	 * without trunk prefix. This is normally not allowed, each MGCP
	 * request should supply an endpoint name with trunk prefix.
	 * However in order to stay compatible with old versions of
	 * osmo-bsc and osmo-msc we still accept endpoint names without
	 * trunk prefix and just assume that the virtual trunk should
	 * be selected. There is even a TTCN3 test for this, see also:
	 * MGCP_Test.TC_crcx_noprefix */
	if ((epname[0] >= '0' && epname[0] <= '9') || (epname[0] >= 'a' && epname[0] <= 'f')) {
		LOGP(DLMGCP, LOGL_ERROR, "missing trunk prefix in endpoint name \"%s\", assuming trunk \"%s\"!\n", epname,
		     MGCP_ENDPOINT_PREFIX_VIRTUAL_TRUNK);
		return cfg->virt_trunk;
	}

	LOGP(DLMGCP, LOGL_ERROR, "unable to find trunk for endpoint name \"%s\"!\n", epname);
	return NULL;
}