/*
  * UDP prototype streaming system

  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard

  *

  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

  * version 2.1 of the License, or (at your option) any later version.

  *

  * FFmpeg 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
  * Lesser General Public License for more details.

  *

  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  */

 
 /**

  * @file

  * UDP protocol
  */
 

 #define _BSD_SOURCE     /* Needed for using struct ip_mreq with recent glibc */

 #include "avformat.h"

 #include "avio_internal.h"

 #include "libavutil/parseutils.h"

 #include "libavutil/fifo.h"

 #include "libavutil/intreadwrite.h"

 #include "libavutil/avstring.h"

 #include "libavutil/opt.h"
 #include "libavutil/log.h"

 #include "internal.h"

 #include "network.h"

 #include "os_support.h"

 #include "url.h"

 #if HAVE_PTHREAD_CANCEL

 #include <pthread.h>

 #endif
 

 #ifndef HAVE_PTHREAD_CANCEL
 #define HAVE_PTHREAD_CANCEL 0
 #endif
 

 #ifndef IPV6_ADD_MEMBERSHIP
 #define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
 #define IPV6_DROP_MEMBERSHIP IPV6_LEAVE_GROUP
 #endif
 

 #define UDP_TX_BUF_SIZE 32768
 #define UDP_MAX_PKT_SIZE 65536
 

 typedef struct {

     const AVClass *class;

     int udp_fd;
     int ttl;

     int buffer_size;

     int is_multicast;
     int local_port;

     int reuse_socket;

     int overrun_nonfatal;

     struct sockaddr_storage dest_addr;

     int dest_addr_len;

     int is_connected;

 
     /* Circular Buffer variables for use in UDP receive code */
     int circular_buffer_size;

     AVFifoBuffer *fifo;

     int circular_buffer_error;

 #if HAVE_PTHREAD_CANCEL

     pthread_t circular_buffer_thread;

     pthread_mutex_t mutex;
     pthread_cond_t cond;

     int thread_started;

 #endif

     uint8_t tmp[UDP_MAX_PKT_SIZE+4];
     int remaining_in_dg;

     char *local_addr;
     int packet_size;
     int timeout;

 } UDPContext;
 

 #define OFFSET(x) offsetof(UDPContext, x)
 #define D AV_OPT_FLAG_DECODING_PARAM
 #define E AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {
 {"buffer_size", "Socket buffer size in bytes", OFFSET(buffer_size), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, D|E },
 {"localport", "Set local port to bind to", OFFSET(local_port), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, D|E },
 {"localaddr", "Choose local IP address", OFFSET(local_addr), AV_OPT_TYPE_STRING, {.str = ""}, 0, 0, D|E },
 {"pkt_size", "Set size of UDP packets", OFFSET(packet_size), AV_OPT_TYPE_INT, {.i64 = 1472}, 0, INT_MAX, D|E },
 {"reuse", "Explicitly allow or disallow reusing UDP sockets", OFFSET(reuse_socket), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, D|E },
 {"ttl", "Set the time to live value (for multicast only)", OFFSET(ttl), AV_OPT_TYPE_INT, {.i64 = 16}, 0, INT_MAX, E },
 {"connect", "Should connect() be called on socket", OFFSET(is_connected), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, D|E },
 /* TODO 'sources', 'block' option */
 {"fifo_size", "Set the UDP receiving circular buffer size, expressed as a number of packets with size of 188 bytes", OFFSET(circular_buffer_size), AV_OPT_TYPE_INT, {.i64 = 7*4096}, 0, INT_MAX, D },
 {"overrun_nonfatal", "Survive in case of UDP receiving circular buffer overrun", OFFSET(overrun_nonfatal), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, D },
 {"timeout", "In read mode: if no data arrived in more than this time interval, raise error", OFFSET(timeout), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, D },
 {NULL}
 };
 
 static const AVClass udp_context_class = {
     .class_name     = "udp",
     .item_name      = av_default_item_name,
     .option         = options,
     .version        = LIBAVUTIL_VERSION_INT,
 };
 

 static void log_net_error(void *ctx, int level, const char* prefix)
 {
     char errbuf[100];
     av_strerror(ff_neterrno(), errbuf, sizeof(errbuf));
     av_log(ctx, level, "%s: %s\n", prefix, errbuf);
 }
 

 static int udp_set_multicast_ttl(int sockfd, int mcastTTL,
                                  struct sockaddr *addr)
 {

 #ifdef IP_MULTICAST_TTL

     if (addr->sa_family == AF_INET) {
         if (setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &mcastTTL, sizeof(mcastTTL)) < 0) {

             log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IP_MULTICAST_TTL)");

             return -1;
         }
     }

 #endif

 #if defined(IPPROTO_IPV6) && defined(IPV6_MULTICAST_HOPS)

     if (addr->sa_family == AF_INET6) {
         if (setsockopt(sockfd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &mcastTTL, sizeof(mcastTTL)) < 0) {

             log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IPV6_MULTICAST_HOPS)");

             return -1;
         }
     }

 #endif

     return 0;
 }
 

 static int udp_join_multicast_group(int sockfd, struct sockaddr *addr)

 {

 #ifdef IP_ADD_MEMBERSHIP

     if (addr->sa_family == AF_INET) {

         struct ip_mreq mreq;
 

         mreq.imr_multiaddr.s_addr = ((struct sockaddr_in *)addr)->sin_addr.s_addr;
         mreq.imr_interface.s_addr= INADDR_ANY;
         if (setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (const void *)&mreq, sizeof(mreq)) < 0) {

             log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IP_ADD_MEMBERSHIP)");

             return -1;
         }
     }

 #endif

 #if HAVE_STRUCT_IPV6_MREQ && defined(IPPROTO_IPV6)

     if (addr->sa_family == AF_INET6) {

         struct ipv6_mreq mreq6;
 

         memcpy(&mreq6.ipv6mr_multiaddr, &(((struct sockaddr_in6 *)addr)->sin6_addr), sizeof(struct in6_addr));
         mreq6.ipv6mr_interface= 0;
         if (setsockopt(sockfd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq6, sizeof(mreq6)) < 0) {

             log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IPV6_ADD_MEMBERSHIP)");

             return -1;
         }
     }

 #endif

     return 0;
 }
 

 static int udp_leave_multicast_group(int sockfd, struct sockaddr *addr)
 {

 #ifdef IP_DROP_MEMBERSHIP

     if (addr->sa_family == AF_INET) {

         struct ip_mreq mreq;
 

         mreq.imr_multiaddr.s_addr = ((struct sockaddr_in *)addr)->sin_addr.s_addr;
         mreq.imr_interface.s_addr= INADDR_ANY;
         if (setsockopt(sockfd, IPPROTO_IP, IP_DROP_MEMBERSHIP, (const void *)&mreq, sizeof(mreq)) < 0) {

             log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IP_DROP_MEMBERSHIP)");

             return -1;
         }
     }

 #endif

 #if HAVE_STRUCT_IPV6_MREQ && defined(IPPROTO_IPV6)

     if (addr->sa_family == AF_INET6) {

         struct ipv6_mreq mreq6;
 

         memcpy(&mreq6.ipv6mr_multiaddr, &(((struct sockaddr_in6 *)addr)->sin6_addr), sizeof(struct in6_addr));
         mreq6.ipv6mr_interface= 0;
         if (setsockopt(sockfd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6)) < 0) {

             log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IPV6_DROP_MEMBERSHIP)");

             return -1;
         }
     }

 #endif

     return 0;
 }
 

 static struct addrinfo* udp_resolve_host(const char *hostname, int port,
                                          int type, int family, int flags)
 {

     struct addrinfo hints = { 0 }, *res = 0;

     int error;
     char sport[16];

     const char *node = 0, *service = "0";

 
     if (port > 0) {

         snprintf(sport, sizeof(sport), "%d", port);

         service = sport;
     }
     if ((hostname) && (hostname[0] != '\0') && (hostname[0] != '?')) {
         node = hostname;
     }

     hints.ai_socktype = type;
     hints.ai_family   = family;
     hints.ai_flags = flags;
     if ((error = getaddrinfo(node, service, &hints, &res))) {

         res = NULL;

         av_log(NULL, AV_LOG_ERROR, "udp_resolve_host: %s\n", gai_strerror(error));

     }
 

     return res;
 }
 

 static int udp_set_multicast_sources(int sockfd, struct sockaddr *addr,
                                      int addr_len, char **sources,
                                      int nb_sources, int include)
 {
 #if HAVE_STRUCT_GROUP_SOURCE_REQ && defined(MCAST_BLOCK_SOURCE) && !defined(_WIN32)
     /* These ones are available in the microsoft SDK, but don't seem to work
      * as on linux, so just prefer the v4-only approach there for now. */
     int i;
     for (i = 0; i < nb_sources; i++) {
         struct group_source_req mreqs;
         int level = addr->sa_family == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
         struct addrinfo *sourceaddr = udp_resolve_host(sources[i], 0,
                                                        SOCK_DGRAM, AF_UNSPEC,
                                                        AI_NUMERICHOST);
         if (!sourceaddr)
             return AVERROR(ENOENT);
 
         mreqs.gsr_interface = 0;
         memcpy(&mreqs.gsr_group, addr, addr_len);
         memcpy(&mreqs.gsr_source, sourceaddr->ai_addr, sourceaddr->ai_addrlen);
         freeaddrinfo(sourceaddr);
 
         if (setsockopt(sockfd, level,
                        include ? MCAST_JOIN_SOURCE_GROUP : MCAST_BLOCK_SOURCE,
                        (const void *)&mreqs, sizeof(mreqs)) < 0) {
             if (include)
                 log_net_error(NULL, AV_LOG_ERROR, "setsockopt(MCAST_JOIN_SOURCE_GROUP)");
             else
                 log_net_error(NULL, AV_LOG_ERROR, "setsockopt(MCAST_BLOCK_SOURCE)");
             return ff_neterrno();
         }
     }
 #elif HAVE_STRUCT_IP_MREQ_SOURCE && defined(IP_BLOCK_SOURCE)
     int i;
     if (addr->sa_family != AF_INET) {
         av_log(NULL, AV_LOG_ERROR,
                "Setting multicast sources only supported for IPv4\n");
         return AVERROR(EINVAL);
     }
     for (i = 0; i < nb_sources; i++) {
         struct ip_mreq_source mreqs;
         struct addrinfo *sourceaddr = udp_resolve_host(sources[i], 0,
                                                        SOCK_DGRAM, AF_UNSPEC,
                                                        AI_NUMERICHOST);
         if (!sourceaddr)
             return AVERROR(ENOENT);
         if (sourceaddr->ai_addr->sa_family != AF_INET) {
             freeaddrinfo(sourceaddr);
             av_log(NULL, AV_LOG_ERROR, "%s is of incorrect protocol family\n",
                    sources[i]);
             return AVERROR(EINVAL);
         }
 
         mreqs.imr_multiaddr.s_addr = ((struct sockaddr_in *)addr)->sin_addr.s_addr;
         mreqs.imr_interface.s_addr = INADDR_ANY;
         mreqs.imr_sourceaddr.s_addr = ((struct sockaddr_in *)sourceaddr->ai_addr)->sin_addr.s_addr;
         freeaddrinfo(sourceaddr);
 
         if (setsockopt(sockfd, IPPROTO_IP,
                        include ? IP_ADD_SOURCE_MEMBERSHIP : IP_BLOCK_SOURCE,
                        (const void *)&mreqs, sizeof(mreqs)) < 0) {
             if (include)
                 log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IP_ADD_SOURCE_MEMBERSHIP)");
             else
                 log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IP_BLOCK_SOURCE)");
             return ff_neterrno();
         }
     }
 #else
     return AVERROR(ENOSYS);
 #endif
     return 0;
 }

 static int udp_set_url(struct sockaddr_storage *addr,
                        const char *hostname, int port)
 {

     struct addrinfo *res0;

     int addr_len;
 

     res0 = udp_resolve_host(hostname, port, SOCK_DGRAM, AF_UNSPEC, 0);

     if (res0 == 0) return AVERROR(EIO);

     memcpy(addr, res0->ai_addr, res0->ai_addrlen);
     addr_len = res0->ai_addrlen;

     freeaddrinfo(res0);

 
     return addr_len;

 }
 

 static int udp_socket_create(UDPContext *s, struct sockaddr_storage *addr,

                              socklen_t *addr_len, const char *localaddr)

 {

     int udp_fd = -1;

     struct addrinfo *res0 = NULL, *res = NULL;

     int family = AF_UNSPEC;

     if (((struct sockaddr *) &s->dest_addr)->sa_family)
         family = ((struct sockaddr *) &s->dest_addr)->sa_family;

     res0 = udp_resolve_host(localaddr[0] ? localaddr : NULL, s->local_port,
                             SOCK_DGRAM, family, AI_PASSIVE);

     if (res0 == 0)
         goto fail;
     for (res = res0; res; res=res->ai_next) {
         udp_fd = socket(res->ai_family, SOCK_DGRAM, 0);

         if (udp_fd != -1) break;

         log_net_error(NULL, AV_LOG_ERROR, "socket");

     }

 
     if (udp_fd < 0)

         goto fail;

     memcpy(addr, res->ai_addr, res->ai_addrlen);
     *addr_len = res->ai_addrlen;

     freeaddrinfo(res0);

     return udp_fd;

  fail:
     if (udp_fd >= 0)
         closesocket(udp_fd);

     if(res0)
         freeaddrinfo(res0);

     return -1;
 }
 

 static int udp_port(struct sockaddr_storage *addr, int addr_len)
 {

     char sbuf[sizeof(int)*3+1];

     int error;

     if ((error = getnameinfo((struct sockaddr *)addr, addr_len, NULL, 0,  sbuf, sizeof(sbuf), NI_NUMERICSERV)) != 0) {
         av_log(NULL, AV_LOG_ERROR, "getnameinfo: %s\n", gai_strerror(error));

         return -1;
     }
 
     return strtol(sbuf, NULL, 10);
 }
 

 /**
  * If no filename is given to av_open_input_file because you want to
  * get the local port first, then you must call this function to set
  * the remote server address.
  *
  * url syntax: udp://host:port[?option=val...]

  * option: 'ttl=n'       : set the ttl value (for multicast only)

  *         'localport=n' : set the local port

  *         'pkt_size=n'  : set max packet size

  *         'reuse=1'     : enable reusing the socket

  *         'overrun_nonfatal=1': survive in case of circular buffer overrun

  *

  * @param h media file context

  * @param uri of the remote server
  * @return zero if no error.
  */

 int ff_udp_set_remote_url(URLContext *h, const char *uri)

 {
     UDPContext *s = h->priv_data;

     char hostname[256], buf[10];

     int port;

     const char *p;

     av_url_split(NULL, 0, NULL, 0, hostname, sizeof(hostname), &port, NULL, 0, uri);

     /* set the destination address */

     s->dest_addr_len = udp_set_url(&s->dest_addr, hostname, port);
     if (s->dest_addr_len < 0) {

         return AVERROR(EIO);

     }

     s->is_multicast = ff_is_multicast_address((struct sockaddr*) &s->dest_addr);

     p = strchr(uri, '?');
     if (p) {

         if (av_find_info_tag(buf, sizeof(buf), "connect", p)) {

             int was_connected = s->is_connected;
             s->is_connected = strtol(buf, NULL, 10);
             if (s->is_connected && !was_connected) {
                 if (connect(s->udp_fd, (struct sockaddr *) &s->dest_addr,
                             s->dest_addr_len)) {
                     s->is_connected = 0;

                     log_net_error(h, AV_LOG_ERROR, "connect");

                     return AVERROR(EIO);
                 }
             }
         }
     }

     return 0;
 }
 
 /**

  * Return the local port used by the UDP connection

  * @param h media file context

  * @return the local port number
  */

 int ff_udp_get_local_port(URLContext *h)

 {
     UDPContext *s = h->priv_data;
     return s->local_port;
 }
 
 /**
  * Return the udp file handle for select() usage to wait for several RTP
  * streams at the same time.
  * @param h media file context
  */

 static int udp_get_file_handle(URLContext *h)

 {
     UDPContext *s = h->priv_data;
     return s->udp_fd;
 }
 

 #if HAVE_PTHREAD_CANCEL

 static void *circular_buffer_task( void *_URLContext)
 {
     URLContext *h = _URLContext;
     UDPContext *s = h->priv_data;

     int old_cancelstate;

     pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_cancelstate);

     pthread_mutex_lock(&s->mutex);

     if (ff_socket_nonblock(s->udp_fd, 0) < 0) {
         av_log(h, AV_LOG_ERROR, "Failed to set blocking mode");
         s->circular_buffer_error = AVERROR(EIO);
         goto end;
     }

     while(1) {

         int len;
 

         pthread_mutex_unlock(&s->mutex);

         /* Blocking operations are always cancellation points;
            see "General Information" / "Thread Cancelation Overview"
            in Single Unix. */
         pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &old_cancelstate);

         len = recv(s->udp_fd, s->tmp+4, sizeof(s->tmp)-4, 0);

         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_cancelstate);

         pthread_mutex_lock(&s->mutex);

         if (len < 0) {
             if (ff_neterrno() != AVERROR(EAGAIN) && ff_neterrno() != AVERROR(EINTR)) {

                 s->circular_buffer_error = ff_neterrno();

                 goto end;

             }

             continue;

         }

         AV_WL32(s->tmp, len);

 
         if(av_fifo_space(s->fifo) < len + 4) {

             /* No Space left */
             if (s->overrun_nonfatal) {
                 av_log(h, AV_LOG_WARNING, "Circular buffer overrun. "
                         "Surviving due to overrun_nonfatal option\n");
                 continue;
             } else {
                 av_log(h, AV_LOG_ERROR, "Circular buffer overrun. "
                         "To avoid, increase fifo_size URL option. "
                         "To survive in such case, use overrun_nonfatal option\n");
                 s->circular_buffer_error = AVERROR(EIO);
                 goto end;
             }
         }

         av_fifo_generic_write(s->fifo, s->tmp, len+4, NULL);

         pthread_cond_signal(&s->cond);

     }
 

 end:
     pthread_cond_signal(&s->cond);
     pthread_mutex_unlock(&s->mutex);

     return NULL;
 }

 #endif

 /* put it in UDP context */

 /* return non zero if error */
 static int udp_open(URLContext *h, const char *uri, int flags)
 {

     char hostname[1024], localaddr[1024] = "";

     int port, udp_fd = -1, tmp, bind_ret = -1;

     UDPContext *s = h->priv_data;

     int is_output;

     const char *p;
     char buf[256];

     struct sockaddr_storage my_addr;

     socklen_t len;

     int reuse_specified = 0;

     int i, include = 0, num_sources = 0;
     char *sources[32];

 
     h->is_streamed = 1;
 

     is_output = !(flags & AVIO_FLAG_READ);

     if (!s->buffer_size) /* if not set explicitly */
         s->buffer_size = is_output ? UDP_TX_BUF_SIZE : UDP_MAX_PKT_SIZE;

     p = strchr(uri, '?');
     if (p) {

         if (av_find_info_tag(buf, sizeof(buf), "reuse", p)) {

             char *endptr = NULL;

             s->reuse_socket = strtol(buf, &endptr, 10);
             /* assume if no digits were found it is a request to enable it */
             if (buf == endptr)
                 s->reuse_socket = 1;
             reuse_specified = 1;
         }

         if (av_find_info_tag(buf, sizeof(buf), "overrun_nonfatal", p)) {
             char *endptr = NULL;
             s->overrun_nonfatal = strtol(buf, &endptr, 10);
             /* assume if no digits were found it is a request to enable it */
             if (buf == endptr)
                 s->overrun_nonfatal = 1;

             if (!HAVE_PTHREAD_CANCEL)
                 av_log(h, AV_LOG_WARNING,
                        "'overrun_nonfatal' option was set but it is not supported "
                        "on this build (pthread support is required)\n");

         }

         if (av_find_info_tag(buf, sizeof(buf), "ttl", p)) {

             s->ttl = strtol(buf, NULL, 10);
         }

         if (av_find_info_tag(buf, sizeof(buf), "localport", p)) {

             s->local_port = strtol(buf, NULL, 10);
         }

         if (av_find_info_tag(buf, sizeof(buf), "pkt_size", p)) {

             s->packet_size = strtol(buf, NULL, 10);

         }

         if (av_find_info_tag(buf, sizeof(buf), "buffer_size", p)) {

             s->buffer_size = strtol(buf, NULL, 10);
         }

         if (av_find_info_tag(buf, sizeof(buf), "connect", p)) {

             s->is_connected = strtol(buf, NULL, 10);
         }

         if (av_find_info_tag(buf, sizeof(buf), "fifo_size", p)) {

             s->circular_buffer_size = strtol(buf, NULL, 10);

             if (!HAVE_PTHREAD_CANCEL)
                 av_log(h, AV_LOG_WARNING,
                        "'circular_buffer_size' option was set but it is not supported "
                        "on this build (pthread support is required)\n");

         }

         if (av_find_info_tag(buf, sizeof(buf), "localaddr", p)) {
             av_strlcpy(localaddr, buf, sizeof(localaddr));
         }

         if (av_find_info_tag(buf, sizeof(buf), "sources", p))
             include = 1;
         if (include || av_find_info_tag(buf, sizeof(buf), "block", p)) {
             char *source_start;
 
             source_start = buf;
             while (1) {
                 char *next = strchr(source_start, ',');
                 if (next)
                     *next = '\0';
                 sources[num_sources] = av_strdup(source_start);
                 if (!sources[num_sources])
                     goto fail;
                 source_start = next + 1;
                 num_sources++;
                 if (num_sources >= FF_ARRAY_ELEMS(sources) || !next)
                     break;
             }
         }

         if (!is_output && av_find_info_tag(buf, sizeof(buf), "timeout", p))

             s->timeout = strtol(buf, NULL, 10);

     }

     /* handling needed to support options picking from both AVOption and URL */
     s->circular_buffer_size *= 188;
     h->max_packet_size = s->packet_size;
     h->rw_timeout = s->timeout;

 
     /* fill the dest addr */

     av_url_split(NULL, 0, NULL, 0, hostname, sizeof(hostname), &port, NULL, 0, uri);

     /* XXX: fix av_url_split */

     if (hostname[0] == '\0' || hostname[0] == '?') {
         /* only accepts null hostname if input */

         if (!(flags & AVIO_FLAG_READ))

             goto fail;
     } else {

         if (ff_udp_set_remote_url(h, uri) < 0)

             goto fail;

     }

     if ((s->is_multicast || !s->local_port) && (h->flags & AVIO_FLAG_READ))

         s->local_port = port;

     udp_fd = udp_socket_create(s, &my_addr, &len, localaddr[0] ? localaddr : s->local_addr);

     if (udp_fd < 0)
         goto fail;
 

     /* Follow the requested reuse option, unless it's multicast in which

      * case enable reuse unless explicitly disabled.

      */
     if (s->reuse_socket || (s->is_multicast && !reuse_specified)) {
         s->reuse_socket = 1;

         if (setsockopt (udp_fd, SOL_SOCKET, SO_REUSEADDR, &(s->reuse_socket), sizeof(s->reuse_socket)) != 0)
             goto fail;

     }

     /* If multicast, try binding the multicast address first, to avoid
      * receiving UDP packets from other sources aimed at the same UDP

      * port. This fails on windows. This makes sending to the same address
      * using sendto() fail, so only do it if we're opened in read-only mode. */
     if (s->is_multicast && !(h->flags & AVIO_FLAG_WRITE)) {

         bind_ret = bind(udp_fd,(struct sockaddr *)&s->dest_addr, len);
     }
     /* bind to the local address if not multicast or if the multicast
      * bind failed */

     /* the bind is needed to give a port to the socket now */

     if (bind_ret < 0 && bind(udp_fd,(struct sockaddr *)&my_addr, len) < 0) {

         log_net_error(h, AV_LOG_ERROR, "bind failed");

         goto fail;

     }

     len = sizeof(my_addr);
     getsockname(udp_fd, (struct sockaddr *)&my_addr, &len);

     s->local_port = udp_port(&my_addr, len);
 

     if (s->is_multicast) {

         if (h->flags & AVIO_FLAG_WRITE) {

             /* output */

             if (udp_set_multicast_ttl(udp_fd, s->ttl, (struct sockaddr *)&s->dest_addr) < 0)

                 goto fail;

         }
         if (h->flags & AVIO_FLAG_READ) {

             /* input */

             if (num_sources == 0 || !include) {
                 if (udp_join_multicast_group(udp_fd, (struct sockaddr *)&s->dest_addr) < 0)
                     goto fail;
 
                 if (num_sources) {
                     if (udp_set_multicast_sources(udp_fd, (struct sockaddr *)&s->dest_addr, s->dest_addr_len, sources, num_sources, 0) < 0)
                         goto fail;
                 }
             } else if (include && num_sources) {
                 if (udp_set_multicast_sources(udp_fd, (struct sockaddr *)&s->dest_addr, s->dest_addr_len, sources, num_sources, 1) < 0)
                     goto fail;
             } else {
                 av_log(NULL, AV_LOG_ERROR, "invalid udp settings: inclusive multicast but no sources given\n");

                 goto fail;

             }

         }
     }

     if (is_output) {
         /* limit the tx buf size to limit latency */

         tmp = s->buffer_size;

         if (setsockopt(udp_fd, SOL_SOCKET, SO_SNDBUF, &tmp, sizeof(tmp)) < 0) {

             log_net_error(h, AV_LOG_ERROR, "setsockopt(SO_SNDBUF)");

             goto fail;
         }

     } else {
         /* set udp recv buffer size to the largest possible udp packet size to
          * avoid losing data on OSes that set this too low by default. */

         tmp = s->buffer_size;
         if (setsockopt(udp_fd, SOL_SOCKET, SO_RCVBUF, &tmp, sizeof(tmp)) < 0) {

             log_net_error(h, AV_LOG_WARNING, "setsockopt(SO_RECVBUF)");

         }

         /* make the socket non-blocking */
         ff_socket_nonblock(udp_fd, 1);

     }

     if (s->is_connected) {
         if (connect(udp_fd, (struct sockaddr *) &s->dest_addr, s->dest_addr_len)) {

             log_net_error(h, AV_LOG_ERROR, "connect");

             goto fail;
         }
     }

     for (i = 0; i < num_sources; i++)

         av_freep(&sources[i]);

     s->udp_fd = udp_fd;

 #if HAVE_PTHREAD_CANCEL

     if (!is_output && s->circular_buffer_size) {

         int ret;
 

         /* start the task going */

         s->fifo = av_fifo_alloc(s->circular_buffer_size);

         ret = pthread_mutex_init(&s->mutex, NULL);
         if (ret != 0) {
             av_log(h, AV_LOG_ERROR, "pthread_mutex_init failed : %s\n", strerror(ret));

             goto fail;
         }

         ret = pthread_cond_init(&s->cond, NULL);
         if (ret != 0) {
             av_log(h, AV_LOG_ERROR, "pthread_cond_init failed : %s\n", strerror(ret));
             goto cond_fail;
         }
         ret = pthread_create(&s->circular_buffer_thread, NULL, circular_buffer_task, h);
         if (ret != 0) {
             av_log(h, AV_LOG_ERROR, "pthread_create failed : %s\n", strerror(ret));
             goto thread_fail;
         }
         s->thread_started = 1;

     }

 #endif

     return 0;

 #if HAVE_PTHREAD_CANCEL

  thread_fail:
     pthread_cond_destroy(&s->cond);
  cond_fail:
     pthread_mutex_destroy(&s->mutex);
 #endif

  fail:

     if (udp_fd >= 0)

         closesocket(udp_fd);

     av_fifo_free(s->fifo);

     for (i = 0; i < num_sources; i++)

         av_freep(&sources[i]);

     return AVERROR(EIO);

 }
 

 static int udp_read(URLContext *h, uint8_t *buf, int size)

 {
     UDPContext *s = h->priv_data;

     int ret;

     int avail, nonblock = h->flags & AVIO_FLAG_NONBLOCK;

 #if HAVE_PTHREAD_CANCEL

     if (s->fifo) {

         pthread_mutex_lock(&s->mutex);

         do {

             avail = av_fifo_size(s->fifo);

             if (avail) { // >=size) {

                 uint8_t tmp[4];
 
                 av_fifo_generic_read(s->fifo, tmp, 4, NULL);
                 avail= AV_RL32(tmp);
                 if(avail > size){
                     av_log(h, AV_LOG_WARNING, "Part of datagram lost due to insufficient buffer size\n");
                     avail= size;
                 }

                 av_fifo_generic_read(s->fifo, buf, avail, NULL);

                 av_fifo_drain(s->fifo, AV_RL32(tmp) - avail);

                 pthread_mutex_unlock(&s->mutex);

                 return avail;

             } else if(s->circular_buffer_error){

                 int err = s->circular_buffer_error;

                 pthread_mutex_unlock(&s->mutex);

                 return err;

             } else if(nonblock) {

                 pthread_mutex_unlock(&s->mutex);
                 return AVERROR(EAGAIN);

             }
             else {

                 /* FIXME: using the monotonic clock would be better,
                    but it does not exist on all supported platforms. */
                 int64_t t = av_gettime() + 100000;
                 struct timespec tv = { .tv_sec  =  t / 1000000,
                                        .tv_nsec = (t % 1000000) * 1000 };

                 if (pthread_cond_timedwait(&s->cond, &s->mutex, &tv) < 0) {
                     pthread_mutex_unlock(&s->mutex);

                     return AVERROR(errno == ETIMEDOUT ? EAGAIN : errno);

                 }

                 nonblock = 1;

             }
         } while( 1);
     }

 #endif

     if (!(h->flags & AVIO_FLAG_NONBLOCK)) {

         ret = ff_network_wait_fd(s->udp_fd, 0);
         if (ret < 0)
             return ret;

     }

     ret = recv(s->udp_fd, buf, size, 0);

     return ret < 0 ? ff_neterrno() : ret;

 }
 

 static int udp_write(URLContext *h, const uint8_t *buf, int size)

 {
     UDPContext *s = h->priv_data;

     int ret;
 

     if (!(h->flags & AVIO_FLAG_NONBLOCK)) {

         ret = ff_network_wait_fd(s->udp_fd, 1);
         if (ret < 0)
             return ret;

     }

 
     if (!s->is_connected) {
         ret = sendto (s->udp_fd, buf, size, 0,
                       (struct sockaddr *) &s->dest_addr,
                       s->dest_addr_len);
     } else
         ret = send(s->udp_fd, buf, size, 0);
 
     return ret < 0 ? ff_neterrno() : ret;

 }
 
 static int udp_close(URLContext *h)
 {
     UDPContext *s = h->priv_data;

     int ret;

     if (s->is_multicast && (h->flags & AVIO_FLAG_READ))

         udp_leave_multicast_group(s->udp_fd, (struct sockaddr *)&s->dest_addr);

     closesocket(s->udp_fd);

 #if HAVE_PTHREAD_CANCEL

     if (s->thread_started) {

         pthread_cancel(s->circular_buffer_thread);

         ret = pthread_join(s->circular_buffer_thread, NULL);
         if (ret != 0)
             av_log(h, AV_LOG_ERROR, "pthread_join(): %s\n", strerror(ret));

         pthread_mutex_destroy(&s->mutex);
         pthread_cond_destroy(&s->cond);

     }

 #endif

     av_fifo_free(s->fifo);

     return 0;

 }
 

 URLProtocol ff_udp_protocol = {

     .name                = "udp",
     .url_open            = udp_open,
     .url_read            = udp_read,
     .url_write           = udp_write,
     .url_close           = udp_close,

     .url_get_file_handle = udp_get_file_handle,

     .priv_data_size      = sizeof(UDPContext),

     .priv_data_class     = &udp_context_class,

     .flags               = URL_PROTOCOL_FLAG_NETWORK,

 };