/* $Id: server.c 4360 2013-02-21 11:26:35Z bennylp $ */
/*
 * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
 * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include "turn.h"
#include "auth.h"

#define MAX_CLIENTS		32
#define MAX_PEERS_PER_CLIENT	8
//#define MAX_HANDLES		(MAX_CLIENTS*MAX_PEERS_PER_CLIENT+MAX_LISTENERS)
#define MAX_HANDLES		PJ_IOQUEUE_MAX_HANDLES
#define MAX_TIMER		(MAX_HANDLES * 2)
#define MIN_PORT		49152
#define MAX_PORT		65535
#define MAX_LISTENERS		16
#define MAX_THREADS		2
#define MAX_NET_EVENTS		1000

/* Prototypes */
static int server_thread_proc(void *arg);
static pj_status_t on_tx_stun_msg( pj_stun_session *sess,
				   void *token,
				   const void *pkt,
				   pj_size_t pkt_size,
				   const pj_sockaddr_t *dst_addr,
				   unsigned addr_len);
static pj_status_t on_rx_stun_request(pj_stun_session *sess,
				      const pj_uint8_t *pkt,
				      unsigned pkt_len,
				      const pj_stun_rx_data *rdata,
				      void *user_data,
				      const pj_sockaddr_t *src_addr,
				      unsigned src_addr_len);

struct saved_cred
{
    pj_str_t realm;
    pj_str_t username;
    pj_str_t nonce;
    int	     data_type;
    pj_str_t data;
};


/*
 * Get transport type name, normally for logging purpose only.
 */
PJ_DEF(const char*) pj_turn_tp_type_name(int tp_type)
{
    /* Must be 3 characters long! */
    if (tp_type == PJ_TURN_TP_UDP) {
	return "UDP";
    } else if (tp_type == PJ_TURN_TP_TCP) {
	return "TCP";
    } else {
	pj_assert(!"Unsupported transport");
	return "???";
    }
}

/*
 * Create server.
 */
PJ_DEF(pj_status_t) pj_turn_srv_create(pj_pool_factory *pf,
				       pj_turn_srv **p_srv)
{
    pj_pool_t *pool;
    pj_stun_session_cb sess_cb;
    pj_turn_srv *srv;
    unsigned i;
    pj_status_t status;

    PJ_ASSERT_RETURN(pf && p_srv, PJ_EINVAL);

    /* Create server and init core settings */
    pool = pj_pool_create(pf, "srv%p", 1000, 1000, NULL);
    srv = PJ_POOL_ZALLOC_T(pool, pj_turn_srv);
    srv->obj_name = pool->obj_name;
    srv->core.pf = pf;
    srv->core.pool = pool;
    srv->core.tls_key = srv->core.tls_data = -1;

    /* Create ioqueue */
    status = pj_ioqueue_create(pool, MAX_HANDLES, &srv->core.ioqueue);
    if (status != PJ_SUCCESS)
	goto on_error;

    /* Server mutex */
    status = pj_lock_create_recursive_mutex(pool, srv->obj_name,
					    &srv->core.lock);
    if (status != PJ_SUCCESS)
	goto on_error;

    /* Allocate TLS */
    status = pj_thread_local_alloc(&srv->core.tls_key);
    if (status != PJ_SUCCESS)
	goto on_error;

    status = pj_thread_local_alloc(&srv->core.tls_data);
    if (status != PJ_SUCCESS)
	goto on_error;

    /* Create timer heap */
    status = pj_timer_heap_create(pool, MAX_TIMER, &srv->core.timer_heap);
    if (status != PJ_SUCCESS)
	goto on_error;

    /* Configure lock for the timer heap */
    pj_timer_heap_set_lock(srv->core.timer_heap, srv->core.lock, PJ_FALSE);

    /* Array of listeners */
    srv->core.listener = (pj_turn_listener**)
			 pj_pool_calloc(pool, MAX_LISTENERS,
					sizeof(srv->core.listener[0]));

    /* Create hash tables */
    srv->tables.alloc = pj_hash_create(pool, MAX_CLIENTS);
    srv->tables.res = pj_hash_create(pool, MAX_CLIENTS);

    /* Init ports settings */
    srv->ports.min_udp = srv->ports.next_udp = MIN_PORT;
    srv->ports.max_udp = MAX_PORT;
    srv->ports.min_tcp = srv->ports.next_tcp = MIN_PORT;
    srv->ports.max_tcp = MAX_PORT;

    /* Init STUN config */
    pj_stun_config_init(&srv->core.stun_cfg, pf, 0, srv->core.ioqueue,
		        srv->core.timer_heap);

    /* Init STUN credential */
    srv->core.cred.type = PJ_STUN_AUTH_CRED_DYNAMIC;
    srv->core.cred.data.dyn_cred.user_data = srv;
    srv->core.cred.data.dyn_cred.get_auth = &pj_turn_get_auth;
    srv->core.cred.data.dyn_cred.get_password = &pj_turn_get_password;
    srv->core.cred.data.dyn_cred.verify_nonce = &pj_turn_verify_nonce;

    /* Create STUN session to handle new allocation */
    pj_bzero(&sess_cb, sizeof(sess_cb));
    sess_cb.on_rx_request = &on_rx_stun_request;
    sess_cb.on_send_msg = &on_tx_stun_msg;

    status = pj_stun_session_create(&srv->core.stun_cfg, srv->obj_name,
				    &sess_cb, PJ_FALSE, NULL,
				    &srv->core.stun_sess);
    if (status != PJ_SUCCESS) {
	goto on_error;
    }

    pj_stun_session_set_user_data(srv->core.stun_sess, srv);
    pj_stun_session_set_credential(srv->core.stun_sess, PJ_STUN_AUTH_LONG_TERM,
				   &srv->core.cred);


    /* Array of worker threads */
    srv->core.thread_cnt = MAX_THREADS;
    srv->core.thread = (pj_thread_t**)
		       pj_pool_calloc(pool, srv->core.thread_cnt,
				      sizeof(pj_thread_t*));

    /* Start the worker threads */
    for (i=0; i<srv->core.thread_cnt; ++i) {
	status = pj_thread_create(pool, srv->obj_name, &server_thread_proc,
				  srv, 0, 0, &srv->core.thread[i]);
	if (status != PJ_SUCCESS)
	    goto on_error;
    }

    /* We're done. Application should add listeners now */
    PJ_LOG(4,(srv->obj_name, "TURN server v%s is running",
	      pj_get_version()));

    *p_srv = srv;
    return PJ_SUCCESS;

on_error:
    pj_turn_srv_destroy(srv);
    return status;
}


/*
 * Handle timer and network events
 */
static void srv_handle_events(pj_turn_srv *srv, const pj_time_val *max_timeout)
{
    /* timeout is 'out' var. This just to make compiler happy. */
    pj_time_val timeout = { 0, 0};
    unsigned net_event_count = 0;
    int c;

    /* Poll the timer. The timer heap has its own mutex for better
     * granularity, so we don't need to lock the server.
     */
    timeout.sec = timeout.msec = 0;
    c = pj_timer_heap_poll( srv->core.timer_heap, &timeout );

    /* timer_heap_poll should never ever returns negative value, or otherwise
     * ioqueue_poll() will block forever!
     */
    pj_assert(timeout.sec >= 0 && timeout.msec >= 0);
    if (timeout.msec >= 1000) timeout.msec = 999;

    /* If caller specifies maximum time to wait, then compare the value with
     * the timeout to wait from timer, and use the minimum value.
     */
    if (max_timeout && PJ_TIME_VAL_GT(timeout, *max_timeout)) {
	timeout = *max_timeout;
    }

    /* Poll ioqueue.
     * Repeat polling the ioqueue while we have immediate events, because
     * timer heap may process more than one events, so if we only process
     * one network events at a time (such as when IOCP backend is used),
     * the ioqueue may have trouble keeping up with the request rate.
     *
     * For example, for each send() request, one network event will be
     *   reported by ioqueue for the send() completion. If we don't poll
     *   the ioqueue often enough, the send() completion will not be
     *   reported in timely manner.
     */
    do {
	c = pj_ioqueue_poll( srv->core.ioqueue, &timeout);
	if (c < 0) {
	    pj_thread_sleep(PJ_TIME_VAL_MSEC(timeout));
	    return;
	} else if (c == 0) {
	    break;
	} else {
	    net_event_count += c;
	    timeout.sec = timeout.msec = 0;
	}
    } while (c > 0 && net_event_count < MAX_NET_EVENTS);

}

/*
 * Server worker thread proc.
 */
static int server_thread_proc(void *arg)
{
    pj_turn_srv *srv = (pj_turn_srv*)arg;

    while (!srv->core.quit) {
	pj_time_val timeout_max = {0, 100};
	srv_handle_events(srv, &timeout_max);
    }

    return 0;
}

/*
 * Destroy the server.
 */
PJ_DEF(pj_status_t) pj_turn_srv_destroy(pj_turn_srv *srv)
{
    pj_hash_iterator_t itbuf, *it;
    unsigned i;

    /* Stop all worker threads */
    srv->core.quit = PJ_TRUE;
    for (i=0; i<srv->core.thread_cnt; ++i) {
	if (srv->core.thread[i]) {
	    pj_thread_join(srv->core.thread[i]);
	    pj_thread_destroy(srv->core.thread[i]);
	    srv->core.thread[i] = NULL;
	}
    }

    /* Destroy all allocations FIRST */
    if (srv->tables.alloc) {
	it = pj_hash_first(srv->tables.alloc, &itbuf);
	while (it != NULL) {
	    pj_turn_allocation *alloc = (pj_turn_allocation*)
					pj_hash_this(srv->tables.alloc, it);
	    pj_hash_iterator_t *next = pj_hash_next(srv->tables.alloc, it);
	    pj_turn_allocation_destroy(alloc);
	    it = next;
	}
    }

    /* Destroy all listeners. */
    for (i=0; i<srv->core.lis_cnt; ++i) {
	if (srv->core.listener[i]) {
	    pj_turn_listener_destroy(srv->core.listener[i]);
	    srv->core.listener[i] = NULL;
	}
    }

    /* Destroy STUN session */
    if (srv->core.stun_sess) {
	pj_stun_session_destroy(srv->core.stun_sess);
	srv->core.stun_sess = NULL;
    }

    /* Destroy hash tables (well, sort of) */
    if (srv->tables.alloc) {
	srv->tables.alloc = NULL;
	srv->tables.res = NULL;
    }

    /* Destroy timer heap */
    if (srv->core.timer_heap) {
	pj_timer_heap_destroy(srv->core.timer_heap);
	srv->core.timer_heap = NULL;
    }

    /* Destroy ioqueue */
    if (srv->core.ioqueue) {
	pj_ioqueue_destroy(srv->core.ioqueue);
	srv->core.ioqueue = NULL;
    }

    /* Destroy thread local IDs */
    if (srv->core.tls_key != -1) {
	pj_thread_local_free(srv->core.tls_key);
	srv->core.tls_key = -1;
    }
    if (srv->core.tls_data != -1) {
	pj_thread_local_free(srv->core.tls_data);
	srv->core.tls_data = -1;
    }

    /* Destroy server lock */
    if (srv->core.lock) {
	pj_lock_destroy(srv->core.lock);
	srv->core.lock = NULL;
    }

    /* Release pool */
    if (srv->core.pool) {
	pj_pool_t *pool = srv->core.pool;
	srv->core.pool = NULL;
	pj_pool_release(pool);
    }

    /* Done */
    return PJ_SUCCESS;
}


/*
 * Add listener.
 */
PJ_DEF(pj_status_t) pj_turn_srv_add_listener(pj_turn_srv *srv,
					     pj_turn_listener *lis)
{
    unsigned index;

    PJ_ASSERT_RETURN(srv && lis, PJ_EINVAL);
    PJ_ASSERT_RETURN(srv->core.lis_cnt < MAX_LISTENERS, PJ_ETOOMANY);

    /* Add to array */
    index = srv->core.lis_cnt;
    srv->core.listener[index] = lis;
    lis->server = srv;
    lis->id = index;
    srv->core.lis_cnt++;

    PJ_LOG(4,(srv->obj_name, "Listener %s/%s added at index %d",
	      lis->obj_name, lis->info, lis->id));

    return PJ_SUCCESS;
}


/*
 * Destroy listener.
 */
PJ_DEF(pj_status_t) pj_turn_listener_destroy(pj_turn_listener *listener)
{
    pj_turn_srv *srv = listener->server;
    unsigned i;

    /* Remove from our listener list */
    pj_lock_acquire(srv->core.lock);
    for (i=0; i<srv->core.lis_cnt; ++i) {
	if (srv->core.listener[i] == listener) {
	    srv->core.listener[i] = NULL;
	    srv->core.lis_cnt--;
	    listener->id = PJ_TURN_INVALID_LIS_ID;
	    break;
	}
    }
    pj_lock_release(srv->core.lock);

    /* Destroy */
    return listener->destroy(listener);
}


/**
 * Add a reference to a transport.
 */
PJ_DEF(void) pj_turn_transport_add_ref( pj_turn_transport *transport,
					pj_turn_allocation *alloc)
{
    transport->add_ref(transport, alloc);
}


/**
 * Decrement transport reference counter.
 */
PJ_DEF(void) pj_turn_transport_dec_ref( pj_turn_transport *transport,
					pj_turn_allocation *alloc)
{
    transport->dec_ref(transport, alloc);
}


/*
 * Register an allocation to the hash tables.
 */
PJ_DEF(pj_status_t) pj_turn_srv_register_allocation(pj_turn_srv *srv,
						    pj_turn_allocation *alloc)
{
    /* Add to hash tables */
    pj_lock_acquire(srv->core.lock);
    pj_hash_set(alloc->pool, srv->tables.alloc,
		&alloc->hkey, sizeof(alloc->hkey), 0, alloc);
    pj_hash_set(alloc->pool, srv->tables.res,
		&alloc->relay.hkey, sizeof(alloc->relay.hkey), 0,
		&alloc->relay);
    pj_lock_release(srv->core.lock);

    return PJ_SUCCESS;
}


/*
 * Unregister an allocation from the hash tables.
 */
PJ_DEF(pj_status_t) pj_turn_srv_unregister_allocation(pj_turn_srv *srv,
						     pj_turn_allocation *alloc)
{
    /* Unregister from hash tables */
    pj_lock_acquire(srv->core.lock);
    pj_hash_set(alloc->pool, srv->tables.alloc,
		&alloc->hkey, sizeof(alloc->hkey), 0, NULL);
    pj_hash_set(alloc->pool, srv->tables.res,
		&alloc->relay.hkey, sizeof(alloc->relay.hkey), 0, NULL);
    pj_lock_release(srv->core.lock);

    return PJ_SUCCESS;
}


/* Callback from our own STUN session whenever it needs to send
 * outgoing STUN packet.
 */
static pj_status_t on_tx_stun_msg( pj_stun_session *sess,
				   void *token,
				   const void *pdu,
				   pj_size_t pdu_size,
				   const pj_sockaddr_t *dst_addr,
				   unsigned addr_len)
{
    pj_turn_transport *transport = (pj_turn_transport*) token;

    PJ_ASSERT_RETURN(transport!=NULL, PJ_EINVALIDOP);

    PJ_UNUSED_ARG(sess);

    return transport->sendto(transport, pdu, pdu_size, 0,
			     dst_addr, addr_len);
}


/* Respond to STUN request */
static pj_status_t stun_respond(pj_stun_session *sess,
				pj_turn_transport *transport,
				const pj_stun_rx_data *rdata,
				unsigned code,
				const char *errmsg,
				pj_bool_t cache,
				const pj_sockaddr_t *dst_addr,
				unsigned addr_len)
{
    pj_status_t status;
    pj_str_t reason;
    pj_stun_tx_data *tdata;

    /* Create response */
    status = pj_stun_session_create_res(sess, rdata, code,
					(errmsg?pj_cstr(&reason,errmsg):NULL),
					&tdata);
    if (status != PJ_SUCCESS)
	return status;

    /* Send the response */
    return pj_stun_session_send_msg(sess, transport, cache, PJ_FALSE,
				    dst_addr,  addr_len, tdata);
}


/* Callback from our own STUN session when incoming request arrives.
 * This function is triggered by pj_stun_session_on_rx_pkt() call in
 * pj_turn_srv_on_rx_pkt() function below.
 */
static pj_status_t on_rx_stun_request(pj_stun_session *sess,
				      const pj_uint8_t *pdu,
				      unsigned pdu_len,
				      const pj_stun_rx_data *rdata,
				      void *token,
				      const pj_sockaddr_t *src_addr,
				      unsigned src_addr_len)
{
    pj_turn_transport *transport;
    const pj_stun_msg *msg = rdata->msg;
    pj_turn_allocation *alloc;
    pj_status_t status;

    PJ_UNUSED_ARG(pdu);
    PJ_UNUSED_ARG(pdu_len);

    transport = (pj_turn_transport*) token;

    /* Respond any requests other than ALLOCATE with 437 response */
    if (msg->hdr.type != PJ_STUN_ALLOCATE_REQUEST) {
	stun_respond(sess, transport, rdata, PJ_STUN_SC_ALLOCATION_MISMATCH,
		     NULL, PJ_FALSE, src_addr, src_addr_len);
	return PJ_SUCCESS;
    }

    /* Create new allocation. The relay resource will be allocated
     * in this function.
     */
    status = pj_turn_allocation_create(transport, src_addr, src_addr_len,
				       rdata, sess, &alloc);
    if (status != PJ_SUCCESS) {
	/* STUN response has been sent, no need to reply here */
	return PJ_SUCCESS;
    }

    /* Done. */
    return PJ_SUCCESS;
}

/* Handle STUN Binding request */
static void handle_binding_request(pj_turn_pkt *pkt,
				   unsigned options)
{
    pj_stun_msg *request, *response;
    pj_uint8_t pdu[200];
    pj_size_t len;
    pj_status_t status;

    /* Decode request */
    status = pj_stun_msg_decode(pkt->pool, pkt->pkt, pkt->len, options,
				&request, NULL, NULL);
    if (status != PJ_SUCCESS)
	return;

    /* Create response */
    status = pj_stun_msg_create_response(pkt->pool, request, 0, NULL,
					 &response);
    if (status != PJ_SUCCESS)
	return;

    /* Add XOR-MAPPED-ADDRESS */
    pj_stun_msg_add_sockaddr_attr(pkt->pool, response,
				  PJ_STUN_ATTR_XOR_MAPPED_ADDR,
				  PJ_TRUE,
				  &pkt->src.clt_addr,
				  pkt->src_addr_len);

    /* Encode */
    status = pj_stun_msg_encode(response, pdu, sizeof(pdu), 0, NULL, &len);
    if (status != PJ_SUCCESS)
	return;

    /* Send response */
    pkt->transport->sendto(pkt->transport, pdu, len, 0,
			   &pkt->src.clt_addr, pkt->src_addr_len);
}

/*
 * This callback is called by UDP listener on incoming packet. This is
 * the first entry for incoming packet (from client) to the server. From
 * here, the packet may be handed over to an allocation if an allocation
 * is found for the client address, or handed over to owned STUN session
 * if an allocation is not found.
 */
PJ_DEF(void) pj_turn_srv_on_rx_pkt(pj_turn_srv *srv,
				   pj_turn_pkt *pkt)
{
    pj_turn_allocation *alloc;

    /* Get TURN allocation from the source address */
    pj_lock_acquire(srv->core.lock);
    alloc = (pj_turn_allocation*)
	    pj_hash_get(srv->tables.alloc, &pkt->src, sizeof(pkt->src), NULL);
    pj_lock_release(srv->core.lock);

    /* If allocation is found, just hand over the packet to the
     * allocation.
     */
    if (alloc) {
	pj_turn_allocation_on_rx_client_pkt(alloc, pkt);
    } else {
	/* Otherwise this is a new client */
	unsigned options;
	pj_size_t parsed_len;
	pj_status_t status;

	/* Check that this is a STUN message */
	options = PJ_STUN_CHECK_PACKET | PJ_STUN_NO_FINGERPRINT_CHECK;
	if (pkt->transport->listener->tp_type == PJ_TURN_TP_UDP)
	    options |= PJ_STUN_IS_DATAGRAM;

	status = pj_stun_msg_check(pkt->pkt, pkt->len, options);
	if (status != PJ_SUCCESS) {
	    /* If the first byte are not STUN, drop the packet. First byte
	     * of STUN message is always 0x00 or 0x01. Otherwise wait for
	     * more data as the data might have come from TCP.
	     *
	     * Also drop packet if it's unreasonably too big, as this might
	     * indicate invalid data that's building up in the buffer.
	     *
	     * Or if packet is a datagram.
	     */
	    if ((*pkt->pkt != 0x00 && *pkt->pkt != 0x01) ||
		pkt->len > 1600 ||
		(options & PJ_STUN_IS_DATAGRAM))
	    {
		char errmsg[PJ_ERR_MSG_SIZE];
		char ip[PJ_INET6_ADDRSTRLEN+10];

		pkt->len = 0;

		pj_strerror(status, errmsg, sizeof(errmsg));
		PJ_LOG(5,(srv->obj_name,
			  "Non-STUN packet from %s is dropped: %s",
			  pj_sockaddr_print(&pkt->src.clt_addr, ip, sizeof(ip), 3),
			  errmsg));
	    }
	    return;
	}

	/* Special handling for Binding Request. We won't give it to the
	 * STUN session since this request is not authenticated.
	 */
	if (pkt->pkt[1] == 1) {
	    handle_binding_request(pkt, options);
	    return;
	}

	/* Hand over processing to STUN session. This will trigger
	 * on_rx_stun_request() callback to be called if the STUN
	 * message is a request.
	 */
	options &= ~PJ_STUN_CHECK_PACKET;
	parsed_len = 0;
	status = pj_stun_session_on_rx_pkt(srv->core.stun_sess, pkt->pkt,
					   pkt->len, options, pkt->transport,
					   &parsed_len, &pkt->src.clt_addr,
					   pkt->src_addr_len);
	if (status != PJ_SUCCESS) {
	    char errmsg[PJ_ERR_MSG_SIZE];
	    char ip[PJ_INET6_ADDRSTRLEN+10];

	    pj_strerror(status, errmsg, sizeof(errmsg));
	    PJ_LOG(5,(srv->obj_name,
		      "Error processing STUN packet from %s: %s",
		      pj_sockaddr_print(&pkt->src.clt_addr, ip, sizeof(ip), 3),
		      errmsg));
	}

	if (pkt->transport->listener->tp_type == PJ_TURN_TP_UDP) {
	    pkt->len = 0;
	} else if (parsed_len > 0) {
	    if (parsed_len == pkt->len) {
		pkt->len = 0;
	    } else {
		pj_memmove(pkt->pkt, pkt->pkt+parsed_len,
			   pkt->len - parsed_len);
		pkt->len -= parsed_len;
	    }
	}
    }
}


