Import pjproject-2.0.1

1 files changed, 915 insertions, 0 deletions

diff --git a/pjmedia/src/pjmedia/transport_udp.c b/pjmedia/src/pjmedia/transport_udp.c
new file mode 100644
index 0000000..76f9bbb
--- /dev/null
+++ b/pjmedia/src/pjmedia/transport_udp.c
@@ -0,0 +1,915 @@
+/* $Id: transport_udp.c 3841 2011-10-24 09:28:13Z ming $ */
+/* 
+ * 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 <pjmedia/transport_udp.h>
+#include <pj/addr_resolv.h>
+#include <pj/assert.h>
+#include <pj/errno.h>
+#include <pj/ioqueue.h>
+#include <pj/log.h>
+#include <pj/pool.h>
+#include <pj/rand.h>
+#include <pj/string.h>
+
+
+/* Maximum size of incoming RTP packet */
+#define RTP_LEN	    PJMEDIA_MAX_MTU
+
+/* Maximum size of incoming RTCP packet */
+#define RTCP_LEN    600
+
+/* Maximum pending write operations */
+#define MAX_PENDING 4
+
+static const pj_str_t ID_RTP_AVP  = { "RTP/AVP", 7 };
+
+/* Pending write buffer */
+typedef struct pending_write
+{
+    char		buffer[RTP_LEN];
+    pj_ioqueue_op_key_t	op_key;
+} pending_write;
+
+
+struct transport_udp
+{
+    pjmedia_transport	base;		/**< Base transport.		    */
+
+    pj_pool_t	       *pool;		/**< Memory pool		    */
+    unsigned		options;	/**< Transport options.		    */
+    unsigned		media_options;	/**< Transport media options.	    */
+    void	       *user_data;	/**< Only valid when attached	    */
+    pj_bool_t		attached;	/**< Has attachment?		    */
+    pj_sockaddr		rem_rtp_addr;	/**< Remote RTP address		    */
+    pj_sockaddr		rem_rtcp_addr;	/**< Remote RTCP address	    */
+    int			addr_len;	/**< Length of addresses.	    */
+    void  (*rtp_cb)(	void*,		/**< To report incoming RTP.	    */
+			void*,
+			pj_ssize_t);
+    void  (*rtcp_cb)(	void*,		/**< To report incoming RTCP.	    */
+			void*,
+			pj_ssize_t);
+
+    unsigned		tx_drop_pct;	/**< Percent of tx pkts to drop.    */
+    unsigned		rx_drop_pct;	/**< Percent of rx pkts to drop.    */
+
+    pj_sock_t	        rtp_sock;	/**< RTP socket			    */
+    pj_sockaddr		rtp_addr_name;	/**< Published RTP address.	    */
+    pj_ioqueue_key_t   *rtp_key;	/**< RTP socket key in ioqueue	    */
+    pj_ioqueue_op_key_t	rtp_read_op;	/**< Pending read operation	    */
+    unsigned		rtp_write_op_id;/**< Next write_op to use	    */
+    pending_write	rtp_pending_write[MAX_PENDING];  /**< Pending write */
+    pj_sockaddr		rtp_src_addr;	/**< Actual packet src addr.	    */
+    unsigned		rtp_src_cnt;	/**< How many pkt from this addr.   */
+    int			rtp_addrlen;	/**< Address length.		    */
+    char		rtp_pkt[RTP_LEN];/**< Incoming RTP packet buffer    */
+
+    pj_sock_t		rtcp_sock;	/**< RTCP socket		    */
+    pj_sockaddr		rtcp_addr_name;	/**< Published RTCP address.	    */
+    pj_sockaddr		rtcp_src_addr;	/**< Actual source RTCP address.    */
+    unsigned		rtcp_src_cnt;	/**< How many pkt from this addr.   */
+    int			rtcp_addr_len;	/**< Length of RTCP src address.    */
+    pj_ioqueue_key_t   *rtcp_key;	/**< RTCP socket key in ioqueue	    */
+    pj_ioqueue_op_key_t rtcp_read_op;	/**< Pending read operation	    */
+    pj_ioqueue_op_key_t rtcp_write_op;	/**< Pending write operation	    */
+    char		rtcp_pkt[RTCP_LEN];/**< Incoming RTCP packet buffer */
+};
+
+
+
+static void on_rx_rtp( pj_ioqueue_key_t *key, 
+                       pj_ioqueue_op_key_t *op_key, 
+                       pj_ssize_t bytes_read);
+static void on_rx_rtcp(pj_ioqueue_key_t *key, 
+                       pj_ioqueue_op_key_t *op_key, 
+                       pj_ssize_t bytes_read);
+
+/*
+ * These are media transport operations.
+ */
+static pj_status_t transport_get_info (pjmedia_transport *tp,
+				       pjmedia_transport_info *info);
+static pj_status_t transport_attach   (pjmedia_transport *tp,
+				       void *user_data,
+				       const pj_sockaddr_t *rem_addr,
+				       const pj_sockaddr_t *rem_rtcp,
+				       unsigned addr_len,
+				       void (*rtp_cb)(void*,
+						      void*,
+						      pj_ssize_t),
+				       void (*rtcp_cb)(void*,
+						       void*,
+						       pj_ssize_t));
+static void	   transport_detach   (pjmedia_transport *tp,
+				       void *strm);
+static pj_status_t transport_send_rtp( pjmedia_transport *tp,
+				       const void *pkt,
+				       pj_size_t size);
+static pj_status_t transport_send_rtcp(pjmedia_transport *tp,
+				       const void *pkt,
+				       pj_size_t size);
+static pj_status_t transport_send_rtcp2(pjmedia_transport *tp,
+				       const pj_sockaddr_t *addr,
+				       unsigned addr_len,
+				       const void *pkt,
+				       pj_size_t size);
+static pj_status_t transport_media_create(pjmedia_transport *tp,
+				       pj_pool_t *pool,
+				       unsigned options,
+				       const pjmedia_sdp_session *sdp_remote,
+				       unsigned media_index);
+static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
+				        pj_pool_t *pool,
+				        pjmedia_sdp_session *sdp_local,
+				        const pjmedia_sdp_session *rem_sdp,
+				        unsigned media_index);
+static pj_status_t transport_media_start (pjmedia_transport *tp,
+				       pj_pool_t *pool,
+				       const pjmedia_sdp_session *sdp_local,
+				       const pjmedia_sdp_session *sdp_remote,
+				       unsigned media_index);
+static pj_status_t transport_media_stop(pjmedia_transport *tp);
+static pj_status_t transport_simulate_lost(pjmedia_transport *tp,
+				       pjmedia_dir dir,
+				       unsigned pct_lost);
+static pj_status_t transport_destroy  (pjmedia_transport *tp);
+
+
+static pjmedia_transport_op transport_udp_op = 
+{
+    &transport_get_info,
+    &transport_attach,
+    &transport_detach,
+    &transport_send_rtp,
+    &transport_send_rtcp,
+    &transport_send_rtcp2,
+    &transport_media_create,
+    &transport_encode_sdp,
+    &transport_media_start,
+    &transport_media_stop,
+    &transport_simulate_lost,
+    &transport_destroy
+};
+
+
+/**
+ * Create UDP stream transport.
+ */
+PJ_DEF(pj_status_t) pjmedia_transport_udp_create( pjmedia_endpt *endpt,
+						  const char *name,
+						  int port,
+						  unsigned options,
+						  pjmedia_transport **p_tp)
+{
+    return pjmedia_transport_udp_create2(endpt, name, NULL, port, options, 
+					p_tp);
+}
+
+/**
+ * Create UDP stream transport.
+ */
+PJ_DEF(pj_status_t) pjmedia_transport_udp_create2(pjmedia_endpt *endpt,
+						  const char *name,
+						  const pj_str_t *addr,
+						  int port,
+						  unsigned options,
+						  pjmedia_transport **p_tp)
+{
+    return pjmedia_transport_udp_create3(endpt, pj_AF_INET(), name,
+					 addr, port, options, p_tp);
+}
+
+/**
+ * Create UDP stream transport.
+ */
+PJ_DEF(pj_status_t) pjmedia_transport_udp_create3(pjmedia_endpt *endpt,
+						  int af,
+						  const char *name,
+						  const pj_str_t *addr,
+						  int port,
+						  unsigned options,
+						  pjmedia_transport **p_tp)
+{
+    pjmedia_sock_info si;
+    pj_status_t status;
+
+    
+    /* Sanity check */
+    PJ_ASSERT_RETURN(endpt && port && p_tp, PJ_EINVAL);
+
+
+    pj_bzero(&si, sizeof(pjmedia_sock_info));
+    si.rtp_sock = si.rtcp_sock = PJ_INVALID_SOCKET;
+
+    /* Create RTP socket */
+    status = pj_sock_socket(af, pj_SOCK_DGRAM(), 0, &si.rtp_sock);
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+    /* Bind RTP socket */
+    status = pj_sockaddr_init(af, &si.rtp_addr_name, addr, (pj_uint16_t)port);
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+    status = pj_sock_bind(si.rtp_sock, &si.rtp_addr_name, 
+			  pj_sockaddr_get_len(&si.rtp_addr_name));
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+
+    /* Create RTCP socket */
+    status = pj_sock_socket(af, pj_SOCK_DGRAM(), 0, &si.rtcp_sock);
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+    /* Bind RTCP socket */
+    status = pj_sockaddr_init(af, &si.rtcp_addr_name, addr, 
+			      (pj_uint16_t)(port+1));
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+    status = pj_sock_bind(si.rtcp_sock, &si.rtcp_addr_name,
+			  pj_sockaddr_get_len(&si.rtcp_addr_name));
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+    
+    /* Create UDP transport by attaching socket info */
+    return pjmedia_transport_udp_attach( endpt, name, &si, options, p_tp);
+
+
+on_error:
+    if (si.rtp_sock != PJ_INVALID_SOCKET)
+	pj_sock_close(si.rtp_sock);
+    if (si.rtcp_sock != PJ_INVALID_SOCKET)
+	pj_sock_close(si.rtcp_sock);
+    return status;
+}
+
+
+/**
+ * Create UDP stream transport from existing socket info.
+ */
+PJ_DEF(pj_status_t) pjmedia_transport_udp_attach( pjmedia_endpt *endpt,
+						  const char *name,
+						  const pjmedia_sock_info *si,
+						  unsigned options,
+						  pjmedia_transport **p_tp)
+{
+    struct transport_udp *tp;
+    pj_pool_t *pool;
+    pj_ioqueue_t *ioqueue;
+    pj_ioqueue_callback rtp_cb, rtcp_cb;
+    pj_ssize_t size;
+    unsigned i;
+    pj_status_t status;
+
+
+    /* Sanity check */
+    PJ_ASSERT_RETURN(endpt && si && p_tp, PJ_EINVAL);
+
+    /* Get ioqueue instance */
+    ioqueue = pjmedia_endpt_get_ioqueue(endpt);
+
+    if (name==NULL)
+	name = "udp%p";
+
+    /* Create transport structure */
+    pool = pjmedia_endpt_create_pool(endpt, name, 512, 512);
+    if (!pool)
+	return PJ_ENOMEM;
+
+    tp = PJ_POOL_ZALLOC_T(pool, struct transport_udp);
+    tp->pool = pool;
+    tp->options = options;
+    pj_memcpy(tp->base.name, pool->obj_name, PJ_MAX_OBJ_NAME);
+    tp->base.op = &transport_udp_op;
+    tp->base.type = PJMEDIA_TRANSPORT_TYPE_UDP;
+
+    /* Copy socket infos */
+    tp->rtp_sock = si->rtp_sock;
+    tp->rtp_addr_name = si->rtp_addr_name;
+    tp->rtcp_sock = si->rtcp_sock;
+    tp->rtcp_addr_name = si->rtcp_addr_name;
+
+    /* If address is 0.0.0.0, use host's IP address */
+    if (!pj_sockaddr_has_addr(&tp->rtp_addr_name)) {
+	pj_sockaddr hostip;
+
+	status = pj_gethostip(tp->rtp_addr_name.addr.sa_family, &hostip);
+	if (status != PJ_SUCCESS)
+	    goto on_error;
+
+	pj_memcpy(pj_sockaddr_get_addr(&tp->rtp_addr_name), 
+		  pj_sockaddr_get_addr(&hostip),
+		  pj_sockaddr_get_addr_len(&hostip));
+    }
+
+    /* Same with RTCP */
+    if (!pj_sockaddr_has_addr(&tp->rtcp_addr_name)) {
+	pj_memcpy(pj_sockaddr_get_addr(&tp->rtcp_addr_name),
+		  pj_sockaddr_get_addr(&tp->rtp_addr_name),
+		  pj_sockaddr_get_addr_len(&tp->rtp_addr_name));
+    }
+
+    /* Setup RTP socket with the ioqueue */
+    pj_bzero(&rtp_cb, sizeof(rtp_cb));
+    rtp_cb.on_read_complete = &on_rx_rtp;
+
+    status = pj_ioqueue_register_sock(pool, ioqueue, tp->rtp_sock, tp,
+				      &rtp_cb, &tp->rtp_key);
+    if (status != PJ_SUCCESS)
+	goto on_error;
+    
+    /* Disallow concurrency so that detach() and destroy() are
+     * synchronized with the callback.
+     */
+    status = pj_ioqueue_set_concurrency(tp->rtp_key, PJ_FALSE);
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+    pj_ioqueue_op_key_init(&tp->rtp_read_op, sizeof(tp->rtp_read_op));
+    for (i=0; i<PJ_ARRAY_SIZE(tp->rtp_pending_write); ++i)
+	pj_ioqueue_op_key_init(&tp->rtp_pending_write[i].op_key, 
+			       sizeof(tp->rtp_pending_write[i].op_key));
+
+    /* Kick of pending RTP read from the ioqueue */
+    tp->rtp_addrlen = sizeof(tp->rtp_src_addr);
+    size = sizeof(tp->rtp_pkt);
+    status = pj_ioqueue_recvfrom(tp->rtp_key, &tp->rtp_read_op,
+			         tp->rtp_pkt, &size, PJ_IOQUEUE_ALWAYS_ASYNC,
+				 &tp->rtp_src_addr, &tp->rtp_addrlen);
+    if (status != PJ_EPENDING)
+	goto on_error;
+
+
+    /* Setup RTCP socket with ioqueue */
+    pj_bzero(&rtcp_cb, sizeof(rtcp_cb));
+    rtcp_cb.on_read_complete = &on_rx_rtcp;
+
+    status = pj_ioqueue_register_sock(pool, ioqueue, tp->rtcp_sock, tp,
+				      &rtcp_cb, &tp->rtcp_key);
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+    status = pj_ioqueue_set_concurrency(tp->rtcp_key, PJ_FALSE);
+    if (status != PJ_SUCCESS)
+	goto on_error;
+
+    pj_ioqueue_op_key_init(&tp->rtcp_read_op, sizeof(tp->rtcp_read_op));
+    pj_ioqueue_op_key_init(&tp->rtcp_write_op, sizeof(tp->rtcp_write_op));
+
+
+    /* Kick of pending RTCP read from the ioqueue */
+    size = sizeof(tp->rtcp_pkt);
+    tp->rtcp_addr_len = sizeof(tp->rtcp_src_addr);
+    status = pj_ioqueue_recvfrom( tp->rtcp_key, &tp->rtcp_read_op,
+				  tp->rtcp_pkt, &size, PJ_IOQUEUE_ALWAYS_ASYNC,
+				  &tp->rtcp_src_addr, &tp->rtcp_addr_len);
+    if (status != PJ_EPENDING)
+	goto on_error;
+
+
+    /* Done */
+    *p_tp = &tp->base;
+    return PJ_SUCCESS;
+
+
+on_error:
+    transport_destroy(&tp->base);
+    return status;
+}
+
+
+/**
+ * Close UDP transport.
+ */
+static pj_status_t transport_destroy(pjmedia_transport *tp)
+{
+    struct transport_udp *udp = (struct transport_udp*) tp;
+
+    /* Sanity check */
+    PJ_ASSERT_RETURN(tp, PJ_EINVAL);
+
+    /* Must not close while application is using this */
+    //PJ_ASSERT_RETURN(!udp->attached, PJ_EINVALIDOP);
+    
+
+    if (udp->rtp_key) {
+	/* This will block the execution if callback is still
+	 * being called.
+	 */
+	pj_ioqueue_unregister(udp->rtp_key);
+	udp->rtp_key = NULL;
+	udp->rtp_sock = PJ_INVALID_SOCKET;
+    } else if (udp->rtp_sock != PJ_INVALID_SOCKET) {
+	pj_sock_close(udp->rtp_sock);
+	udp->rtp_sock = PJ_INVALID_SOCKET;
+    }
+
+    if (udp->rtcp_key) {
+	pj_ioqueue_unregister(udp->rtcp_key);
+	udp->rtcp_key = NULL;
+	udp->rtcp_sock = PJ_INVALID_SOCKET;
+    } else if (udp->rtcp_sock != PJ_INVALID_SOCKET) {
+	pj_sock_close(udp->rtcp_sock);
+	udp->rtcp_sock = PJ_INVALID_SOCKET;
+    }
+
+    pj_pool_release(udp->pool);
+
+    return PJ_SUCCESS;
+}
+
+
+/* Notification from ioqueue about incoming RTP packet */
+static void on_rx_rtp( pj_ioqueue_key_t *key, 
+                       pj_ioqueue_op_key_t *op_key, 
+                       pj_ssize_t bytes_read)
+{
+    struct transport_udp *udp;
+    pj_status_t status;
+
+    PJ_UNUSED_ARG(op_key);
+
+    udp = (struct transport_udp*) pj_ioqueue_get_user_data(key);
+
+    do {
+	void (*cb)(void*,void*,pj_ssize_t);
+	void *user_data;
+	pj_bool_t discard = PJ_FALSE;
+
+	cb = udp->rtp_cb;
+	user_data = udp->user_data;
+
+	/* Simulate packet lost on RX direction */
+	if (udp->rx_drop_pct) {
+	    if ((pj_rand() % 100) <= (int)udp->rx_drop_pct) {
+		PJ_LOG(5,(udp->base.name, 
+			  "RX RTP packet dropped because of pkt lost "
+			  "simulation"));
+		discard = PJ_TRUE;
+	    }
+	}
+
+	/* See if source address of RTP packet is different than the 
+	 * configured address, and switch RTP remote address to 
+	 * source packet address after several consecutive packets
+	 * have been received.
+	 */
+	if (bytes_read>0 && 
+	    (udp->options & PJMEDIA_UDP_NO_SRC_ADDR_CHECKING)==0) 
+	{
+	    if (pj_sockaddr_cmp(&udp->rem_rtp_addr, &udp->rtp_src_addr) == 0) {
+		/* We're still receiving from rem_rtp_addr. Don't switch. */
+		udp->rtp_src_cnt = 0;
+	    } else {
+		udp->rtp_src_cnt++;
+
+		if (udp->rtp_src_cnt < PJMEDIA_RTP_NAT_PROBATION_CNT) {
+		    discard = PJ_TRUE;
+		} else {
+		
+		    char addr_text[80];
+
+		    /* Set remote RTP address to source address */
+		    pj_memcpy(&udp->rem_rtp_addr, &udp->rtp_src_addr,
+			      sizeof(pj_sockaddr));
+
+		    /* Reset counter */
+		    udp->rtp_src_cnt = 0;
+
+		    PJ_LOG(4,(udp->base.name,
+			      "Remote RTP address switched to %s",
+			      pj_sockaddr_print(&udp->rtp_src_addr, addr_text,
+						sizeof(addr_text), 3)));
+
+		    /* Also update remote RTCP address if actual RTCP source
+		     * address is not heard yet.
+		     */
+		    if (!pj_sockaddr_has_addr(&udp->rtcp_src_addr)) {
+			pj_uint16_t port;
+
+			pj_memcpy(&udp->rem_rtcp_addr, &udp->rem_rtp_addr, 
+				  sizeof(pj_sockaddr));
+			pj_sockaddr_copy_addr(&udp->rem_rtcp_addr,
+					      &udp->rem_rtp_addr);
+			port = (pj_uint16_t)
+			       (pj_sockaddr_get_port(&udp->rem_rtp_addr)+1);
+			pj_sockaddr_set_port(&udp->rem_rtcp_addr, port);
+
+			pj_memcpy(&udp->rtcp_src_addr, &udp->rem_rtcp_addr, 
+				  sizeof(pj_sockaddr));
+
+			PJ_LOG(4,(udp->base.name,
+				  "Remote RTCP address switched to predicted"
+				  " address %s",
+				  pj_sockaddr_print(&udp->rtcp_src_addr, 
+						    addr_text,
+						    sizeof(addr_text), 3)));
+
+		    }
+		}
+	    }
+	}
+
+	if (!discard && udp->attached && cb)
+	    (*cb)(user_data, udp->rtp_pkt, bytes_read);
+
+	bytes_read = sizeof(udp->rtp_pkt);
+	udp->rtp_addrlen = sizeof(udp->rtp_src_addr);
+	status = pj_ioqueue_recvfrom(udp->rtp_key, &udp->rtp_read_op,
+				     udp->rtp_pkt, &bytes_read, 0,
+				     &udp->rtp_src_addr, 
+				     &udp->rtp_addrlen);
+
+	if (status != PJ_EPENDING && status != PJ_SUCCESS)
+	    bytes_read = -status;
+
+    } while (status != PJ_EPENDING && status != PJ_ECANCELLED);
+}
+
+
+/* Notification from ioqueue about incoming RTCP packet */
+static void on_rx_rtcp(pj_ioqueue_key_t *key, 
+                       pj_ioqueue_op_key_t *op_key, 
+                       pj_ssize_t bytes_read)
+{
+    struct transport_udp *udp;
+    pj_status_t status;
+
+    PJ_UNUSED_ARG(op_key);
+
+    udp = (struct transport_udp*) pj_ioqueue_get_user_data(key);
+
+    do {
+	void (*cb)(void*,void*,pj_ssize_t);
+	void *user_data;
+
+	cb = udp->rtcp_cb;
+	user_data = udp->user_data;
+
+	if (udp->attached && cb)
+	    (*cb)(user_data, udp->rtcp_pkt, bytes_read);
+
+	/* Check if RTCP source address is the same as the configured
+	 * remote address, and switch the address when they are
+	 * different.
+	 */
+	if (bytes_read>0 &&
+	    (udp->options & PJMEDIA_UDP_NO_SRC_ADDR_CHECKING)==0)
+	{
+	    if (pj_sockaddr_cmp(&udp->rem_rtcp_addr, &udp->rtcp_src_addr) == 0) {
+		/* Still receiving from rem_rtcp_addr, don't switch */
+		udp->rtcp_src_cnt = 0;
+	    } else {
+		++udp->rtcp_src_cnt;
+
+		if (udp->rtcp_src_cnt >= PJMEDIA_RTCP_NAT_PROBATION_CNT	) {
+		    char addr_text[80];
+
+		    udp->rtcp_src_cnt = 0;
+		    pj_memcpy(&udp->rem_rtcp_addr, &udp->rtcp_src_addr,
+			      sizeof(pj_sockaddr));
+
+		    PJ_LOG(4,(udp->base.name,
+			      "Remote RTCP address switched to %s",
+			      pj_sockaddr_print(&udp->rtcp_src_addr, addr_text,
+						sizeof(addr_text), 3)));
+		}
+	    }
+	}
+
+	bytes_read = sizeof(udp->rtcp_pkt);
+	udp->rtcp_addr_len = sizeof(udp->rtcp_src_addr);
+	status = pj_ioqueue_recvfrom(udp->rtcp_key, &udp->rtcp_read_op,
+				     udp->rtcp_pkt, &bytes_read, 0,
+				     &udp->rtcp_src_addr, 
+				     &udp->rtcp_addr_len);
+	if (status != PJ_EPENDING && status != PJ_SUCCESS)
+	    bytes_read = -status;
+
+    } while (status != PJ_EPENDING && status != PJ_ECANCELLED);
+}
+
+
+/* Called to get the transport info */
+static pj_status_t transport_get_info(pjmedia_transport *tp,
+				      pjmedia_transport_info *info)
+{
+    struct transport_udp *udp = (struct transport_udp*)tp;
+    PJ_ASSERT_RETURN(tp && info, PJ_EINVAL);
+
+    info->sock_info.rtp_sock = udp->rtp_sock;
+    info->sock_info.rtp_addr_name = udp->rtp_addr_name;
+    info->sock_info.rtcp_sock = udp->rtcp_sock;
+    info->sock_info.rtcp_addr_name = udp->rtcp_addr_name;
+
+    /* Get remote address originating RTP & RTCP. */
+    info->src_rtp_name  = udp->rtp_src_addr;
+    info->src_rtcp_name = udp->rtcp_src_addr;
+
+    return PJ_SUCCESS;
+}
+
+
+/* Called by application to initialize the transport */
+static pj_status_t transport_attach(   pjmedia_transport *tp,
+				       void *user_data,
+				       const pj_sockaddr_t *rem_addr,
+				       const pj_sockaddr_t *rem_rtcp,
+				       unsigned addr_len,
+				       void (*rtp_cb)(void*,
+						      void*,
+						      pj_ssize_t),
+				       void (*rtcp_cb)(void*,
+						       void*,
+						       pj_ssize_t))
+{
+    struct transport_udp *udp = (struct transport_udp*) tp;
+    const pj_sockaddr *rtcp_addr;
+
+    /* Validate arguments */
+    PJ_ASSERT_RETURN(tp && rem_addr && addr_len, PJ_EINVAL);
+
+    /* Must not be "attached" to existing application */
+    PJ_ASSERT_RETURN(!udp->attached, PJ_EINVALIDOP);
+
+    /* Lock the ioqueue keys to make sure that callbacks are
+     * not executed. See ticket #844 for details.
+     */
+    pj_ioqueue_lock_key(udp->rtp_key);
+    pj_ioqueue_lock_key(udp->rtcp_key);
+
+    /* "Attach" the application: */
+
+    /* Copy remote RTP address */
+    pj_memcpy(&udp->rem_rtp_addr, rem_addr, addr_len);
+
+    /* Copy remote RTP address, if one is specified. */
+    rtcp_addr = (const pj_sockaddr*) rem_rtcp;
+    if (rtcp_addr && pj_sockaddr_has_addr(rtcp_addr)) {
+	pj_memcpy(&udp->rem_rtcp_addr, rem_rtcp, addr_len);
+
+    } else {
+	unsigned rtcp_port;
+
+	/* Otherwise guess the RTCP address from the RTP address */
+	pj_memcpy(&udp->rem_rtcp_addr, rem_addr, addr_len);
+	rtcp_port = pj_sockaddr_get_port(&udp->rem_rtp_addr) + 1;
+	pj_sockaddr_set_port(&udp->rem_rtcp_addr, (pj_uint16_t)rtcp_port);
+    }
+
+    /* Save the callbacks */
+    udp->rtp_cb = rtp_cb;
+    udp->rtcp_cb = rtcp_cb;
+    udp->user_data = user_data;
+
+    /* Save address length */
+    udp->addr_len = addr_len;
+
+    /* Last, mark transport as attached */
+    udp->attached = PJ_TRUE;
+
+    /* Reset source RTP & RTCP addresses and counter */
+    pj_bzero(&udp->rtp_src_addr, sizeof(udp->rtp_src_addr));
+    pj_bzero(&udp->rtcp_src_addr, sizeof(udp->rtcp_src_addr));
+    udp->rtp_src_cnt = 0;
+    udp->rtcp_src_cnt = 0;
+
+    /* Unlock keys */
+    pj_ioqueue_unlock_key(udp->rtcp_key);
+    pj_ioqueue_unlock_key(udp->rtp_key);
+
+    return PJ_SUCCESS;
+}
+
+
+/* Called by application when it no longer needs the transport */
+static void transport_detach( pjmedia_transport *tp,
+			      void *user_data)
+{
+    struct transport_udp *udp = (struct transport_udp*) tp;
+
+    pj_assert(tp);
+
+    if (udp->attached) {
+	/* Lock the ioqueue keys to make sure that callbacks are
+	 * not executed. See ticket #460 for details.
+	 */
+	pj_ioqueue_lock_key(udp->rtp_key);
+	pj_ioqueue_lock_key(udp->rtcp_key);
+
+	/* User data is unreferenced on Release build */
+	PJ_UNUSED_ARG(user_data);
+
+	/* As additional checking, check if the same user data is specified */
+	pj_assert(user_data == udp->user_data);
+
+	/* First, mark transport as unattached */
+	udp->attached = PJ_FALSE;
+
+	/* Clear up application infos from transport */
+	udp->rtp_cb = NULL;
+	udp->rtcp_cb = NULL;
+	udp->user_data = NULL;
+
+	/* Unlock keys */
+	pj_ioqueue_unlock_key(udp->rtcp_key);
+	pj_ioqueue_unlock_key(udp->rtp_key);
+    }
+}
+
+
+/* Called by application to send RTP packet */
+static pj_status_t transport_send_rtp( pjmedia_transport *tp,
+				       const void *pkt,
+				       pj_size_t size)
+{
+    struct transport_udp *udp = (struct transport_udp*)tp;
+    pj_ssize_t sent;
+    unsigned id;
+    struct pending_write *pw;
+    pj_status_t status;
+
+    /* Must be attached */
+    PJ_ASSERT_RETURN(udp->attached, PJ_EINVALIDOP);
+
+    /* Check that the size is supported */
+    PJ_ASSERT_RETURN(size <= RTP_LEN, PJ_ETOOBIG);
+
+    /* Simulate packet lost on TX direction */
+    if (udp->tx_drop_pct) {
+	if ((pj_rand() % 100) <= (int)udp->tx_drop_pct) {
+	    PJ_LOG(5,(udp->base.name, 
+		      "TX RTP packet dropped because of pkt lost "
+		      "simulation"));
+	    return PJ_SUCCESS;
+	}
+    }
+
+
+    id = udp->rtp_write_op_id;
+    pw = &udp->rtp_pending_write[id];
+
+    /* We need to copy packet to our buffer because when the
+     * operation is pending, caller might write something else
+     * to the original buffer.
+     */
+    pj_memcpy(pw->buffer, pkt, size);
+
+    sent = size;
+    status = pj_ioqueue_sendto( udp->rtp_key, 
+				&udp->rtp_pending_write[id].op_key,
+				pw->buffer, &sent, 0,
+				&udp->rem_rtp_addr, 
+				udp->addr_len);
+
+    udp->rtp_write_op_id = (udp->rtp_write_op_id + 1) %
+			   PJ_ARRAY_SIZE(udp->rtp_pending_write);
+
+    if (status==PJ_SUCCESS || status==PJ_EPENDING)
+	return PJ_SUCCESS;
+
+    return status;
+}
+
+/* Called by application to send RTCP packet */
+static pj_status_t transport_send_rtcp(pjmedia_transport *tp,
+				       const void *pkt,
+				       pj_size_t size)
+{
+    return transport_send_rtcp2(tp, NULL, 0, pkt, size);
+}
+
+
+/* Called by application to send RTCP packet */
+static pj_status_t transport_send_rtcp2(pjmedia_transport *tp,
+					const pj_sockaddr_t *addr,
+					unsigned addr_len,
+				        const void *pkt,
+				        pj_size_t size)
+{
+    struct transport_udp *udp = (struct transport_udp*)tp;
+    pj_ssize_t sent;
+    pj_status_t status;
+
+    PJ_ASSERT_RETURN(udp->attached, PJ_EINVALIDOP);
+
+    if (addr == NULL) {
+	addr = &udp->rem_rtcp_addr;
+	addr_len = udp->addr_len;
+    }
+
+    sent = size;
+    status = pj_ioqueue_sendto( udp->rtcp_key, &udp->rtcp_write_op,
+				pkt, &sent, 0, addr, addr_len);
+
+    if (status==PJ_SUCCESS || status==PJ_EPENDING)
+	return PJ_SUCCESS;
+
+    return status;
+}
+
+
+static pj_status_t transport_media_create(pjmedia_transport *tp,
+				  pj_pool_t *pool,
+				  unsigned options,
+				  const pjmedia_sdp_session *sdp_remote,
+				  unsigned media_index)
+{
+    struct transport_udp *udp = (struct transport_udp*)tp;
+
+    PJ_ASSERT_RETURN(tp && pool, PJ_EINVAL);
+    udp->media_options = options;
+
+    PJ_UNUSED_ARG(sdp_remote);
+    PJ_UNUSED_ARG(media_index);
+
+    return PJ_SUCCESS;
+}
+
+static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
+				        pj_pool_t *pool,
+				        pjmedia_sdp_session *sdp_local,
+				        const pjmedia_sdp_session *rem_sdp,
+				        unsigned media_index)
+{
+    struct transport_udp *udp = (struct transport_udp*)tp;
+
+    /* Validate media transport */
+    /* By now, this transport only support RTP/AVP transport */
+    if ((udp->media_options & PJMEDIA_TPMED_NO_TRANSPORT_CHECKING) == 0) {
+	pjmedia_sdp_media *m_rem, *m_loc;
+
+	m_rem = rem_sdp? rem_sdp->media[media_index] : NULL;
+	m_loc = sdp_local->media[media_index];
+
+	if (pj_stricmp(&m_loc->desc.transport, &ID_RTP_AVP) ||
+	   (m_rem && pj_stricmp(&m_rem->desc.transport, &ID_RTP_AVP)))
+	{
+	    pjmedia_sdp_media_deactivate(pool, m_loc);
+	    return PJMEDIA_SDP_EINPROTO;
+	}
+    }
+
+    return PJ_SUCCESS;
+}
+
+static pj_status_t transport_media_start(pjmedia_transport *tp,
+				  pj_pool_t *pool,
+				  const pjmedia_sdp_session *sdp_local,
+				  const pjmedia_sdp_session *sdp_remote,
+				  unsigned media_index)
+{
+    PJ_ASSERT_RETURN(tp && pool && sdp_local, PJ_EINVAL);
+
+    PJ_UNUSED_ARG(tp);
+    PJ_UNUSED_ARG(pool);
+    PJ_UNUSED_ARG(sdp_local);
+    PJ_UNUSED_ARG(sdp_remote);
+    PJ_UNUSED_ARG(media_index);
+
+    return PJ_SUCCESS;
+}
+
+static pj_status_t transport_media_stop(pjmedia_transport *tp)
+{
+    PJ_UNUSED_ARG(tp);
+
+    return PJ_SUCCESS;
+}
+
+static pj_status_t transport_simulate_lost(pjmedia_transport *tp,
+					   pjmedia_dir dir,
+					   unsigned pct_lost)
+{
+    struct transport_udp *udp = (struct transport_udp*)tp;
+
+    PJ_ASSERT_RETURN(tp && pct_lost <= 100, PJ_EINVAL);
+
+    if (dir & PJMEDIA_DIR_ENCODING)
+	udp->tx_drop_pct = pct_lost;
+    
+    if (dir & PJMEDIA_DIR_DECODING)
+	udp->rx_drop_pct = pct_lost;
+
+    return PJ_SUCCESS;
+}
+