src/network/udp.c

   1 /*****************************************************************************
   2  * udp.c:
   3  *****************************************************************************
   4  * Copyright (C) 2004-2006 VLC authors and VideoLAN
   5  * Copyright © 2006-2007 Rémi Denis-Courmont
   6  *
   7  * $Id$
   8  *
   9  * Authors: Laurent Aimar <fenrir@videolan.org>
  10  *          Rémi Denis-Courmont <rem # videolan.org>
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU Lesser General Public License as published by
  14  * the Free Software Foundation; either version 2.1 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  20  * GNU Lesser General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Lesser General Public License
  23  * along with this program; if not, write to the Free Software Foundation,
  24  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  25  *****************************************************************************/
  26
  27 /*****************************************************************************
  28  * Preamble
  29  *****************************************************************************/
  30 #ifdef HAVE_CONFIG_H
  31 # include "config.h"
  32 #endif
  33
  34 #include <vlc_common.h>
  35
  36 #include <errno.h>
  37 #include <assert.h>
  38
  39 #include <vlc_network.h>
  40
  41 #ifdef WIN32
  42 #   define EAFNOSUPPORT WSAEAFNOSUPPORT
  43 #else
  44 #   include <unistd.h>
  45 #   ifdef HAVE_NET_IF_H
  46 #       include <net/if.h>
  47 #   endif
  48 #endif
  49
  50 #ifdef HAVE_LINUX_DCCP_H
  51 # include <linux/dccp.h>
  52 # ifndef SOCK_DCCP /* provisional API */
  53 #  define SOCK_DCCP 6
  54 # endif
  55 #endif
  56
  57 #ifndef SOL_IP
  58 # define SOL_IP IPPROTO_IP
  59 #endif
  60 #ifndef SOL_IPV6
  61 # define SOL_IPV6 IPPROTO_IPV6
  62 #endif
  63 #ifndef IPPROTO_IPV6
  64 # define IPPROTO_IPV6 41 /* IANA */
  65 #endif
  66 #ifndef SOL_DCCP
  67 # define SOL_DCCP IPPROTO_DCCP
  68 #endif
  69 #ifndef IPPROTO_DCCP
  70 # define IPPROTO_DCCP 33 /* IANA */
  71 #endif
  72 #ifndef SOL_UDPLITE
  73 # define SOL_UDPLITE IPPROTO_UDPLITE
  74 #endif
  75 #ifndef IPPROTO_UDPLITE
  76 # define IPPROTO_UDPLITE 136 /* IANA */
  77 #endif
  78
  79 #if defined (HAVE_NETINET_UDPLITE_H)
  80 # include <netinet/udplite.h>
  81 #elif defined (__linux__)
  82 /* still missing from glibc 2.6 */
  83 # define UDPLITE_SEND_CSCOV     10
  84 # define UDPLITE_RECV_CSCOV     11
  85 #endif
  86
  87 extern int net_Socket( vlc_object_t *p_this, int i_family, int i_socktype,
  88                        int i_protocol );
  89
  90 /* */
  91 static int net_SetupDgramSocket (vlc_object_t *p_obj, int fd,
  92                                  const struct addrinfo *ptr)
  93 {
  94 #ifdef SO_REUSEPORT
  95     setsockopt (fd, SOL_SOCKET, SO_REUSEPORT, &(int){ 1 }, sizeof (int));
  96 #endif
  97
  98 #ifdef SO_RCVBUF
  99     /* Increase the receive buffer size to 1/2MB (8Mb/s during 1/2s)
 100      * to avoid packet loss caused in case of scheduling hiccups */
 101     setsockopt (fd, SOL_SOCKET, SO_RCVBUF,
 102                 (void *)&(int){ 0x80000 }, sizeof (int));
 103     setsockopt (fd, SOL_SOCKET, SO_SNDBUF,
 104                 (void *)&(int){ 0x80000 }, sizeof (int));
 105 #endif
 106
 107 #if defined (WIN32)
 108     if (net_SockAddrIsMulticast (ptr->ai_addr, ptr->ai_addrlen)
 109      && (sizeof (struct sockaddr_storage) >= ptr->ai_addrlen))
 110     {
 111         // This works for IPv4 too - don't worry!
 112         struct sockaddr_in6 dumb =
 113         {
 114             .sin6_family = ptr->ai_addr->sa_family,
 115             .sin6_port =  ((struct sockaddr_in *)(ptr->ai_addr))->sin_port
 116         };
 117
 118         bind (fd, (struct sockaddr *)&dumb, ptr->ai_addrlen);
 119     }
 120     else
 121 #endif
 122     if (bind (fd, ptr->ai_addr, ptr->ai_addrlen))
 123     {
 124         msg_Err( p_obj, "socket bind error (%m)" );
 125         net_Close (fd);
 126         return -1;
 127     }
 128     return fd;
 129 }
 130
 131 /* */
 132 static int net_ListenSingle (vlc_object_t *obj, const char *host, int port,
 133                              int protocol)
 134 {
 135     struct addrinfo hints = {
 136         .ai_socktype = SOCK_DGRAM,
 137         .ai_protocol = protocol,
 138         .ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_IDN,
 139     }, *res;
 140
 141     if (host && !*host)
 142         host = NULL;
 143
 144     msg_Dbg (obj, "net: opening %s datagram port %d",
 145              host ? host : "any", port);
 146
 147     int val = vlc_getaddrinfo (host, port, &hints, &res);
 148     if (val)
 149     {
 150         msg_Err (obj, "Cannot resolve %s port %d : %s", host, port,
 151                  gai_strerror (val));
 152         return -1;
 153     }
 154
 155     val = -1;
 156
 157     for (const struct addrinfo *ptr = res; ptr != NULL; ptr = ptr->ai_next)
 158     {
 159         int fd = net_Socket (obj, ptr->ai_family, ptr->ai_socktype,
 160                              ptr->ai_protocol);
 161         if (fd == -1)
 162         {
 163             msg_Dbg (obj, "socket error: %m");
 164             continue;
 165         }
 166
 167 #ifdef IPV6_V6ONLY
 168         /* Try dual-mode IPv6 if available. */
 169         if (ptr->ai_family == AF_INET6)
 170             setsockopt (fd, SOL_IPV6, IPV6_V6ONLY, &(int){ 0 }, sizeof (int));
 171 #endif
 172         fd = net_SetupDgramSocket( obj, fd, ptr );
 173         if( fd == -1 )
 174             continue;
 175
 176         if (net_SockAddrIsMulticast (ptr->ai_addr, ptr->ai_addrlen)
 177          && net_Subscribe (obj, fd, ptr->ai_addr, ptr->ai_addrlen))
 178         {
 179             net_Close (fd);
 180             continue;
 181         }
 182
 183         val = fd;
 184         break;
 185     }
 186
 187     freeaddrinfo (res);
 188     return val;
 189 }
 190
 191
 192 static int net_SetMcastHopLimit( vlc_object_t *p_this,
 193                                  int fd, int family, int hlim )
 194 {
 195     int proto, cmd;
 196
 197     /* There is some confusion in the world whether IP_MULTICAST_TTL
 198      * takes a byte or an int as an argument.
 199      * BSD seems to indicate byte so we are going with that and use
 200      * int as a fallback to be safe */
 201     switch( family )
 202     {
 203 #ifdef IP_MULTICAST_TTL
 204         case AF_INET:
 205             proto = SOL_IP;
 206             cmd = IP_MULTICAST_TTL;
 207             break;
 208 #endif
 209
 210 #ifdef IPV6_MULTICAST_HOPS
 211         case AF_INET6:
 212             proto = SOL_IPV6;
 213             cmd = IPV6_MULTICAST_HOPS;
 214             break;
 215 #endif
 216
 217         default:
 218             errno = EAFNOSUPPORT;
 219             msg_Warn( p_this, "%m" );
 220             return VLC_EGENERIC;
 221     }
 222
 223     if( setsockopt( fd, proto, cmd, &hlim, sizeof( hlim ) ) < 0 )
 224     {
 225         /* BSD compatibility */
 226         unsigned char buf;
 227
 228         msg_Dbg( p_this, "cannot set hop limit (%d): %m", hlim );
 229         buf = (unsigned char)(( hlim > 255 ) ? 255 : hlim);
 230         if( setsockopt( fd, proto, cmd, &buf, sizeof( buf ) ) )
 231         {
 232             msg_Err( p_this, "cannot set hop limit (%d): %m", hlim );
 233             return VLC_EGENERIC;
 234         }
 235     }
 236
 237     return VLC_SUCCESS;
 238 }
 239
 240
 241 static int net_SetMcastOut (vlc_object_t *p_this, int fd, int family,
 242                             const char *iface)
 243 {
 244     int scope = if_nametoindex (iface);
 245     if (scope == 0)
 246     {
 247         msg_Err (p_this, "invalid multicast interface: %s", iface);
 248         return -1;
 249     }
 250
 251     switch (family)
 252     {
 253 #ifdef IPV6_MULTICAST_IF
 254         case AF_INET6:
 255             if (setsockopt (fd, SOL_IPV6, IPV6_MULTICAST_IF,
 256                             &scope, sizeof (scope)) == 0)
 257                 return 0;
 258 #endif
 259
 260 #ifdef __linux__
 261         case AF_INET:
 262         {
 263             struct ip_mreqn req = { .imr_ifindex = scope };
 264             if (setsockopt (fd, SOL_IP, IP_MULTICAST_IF,
 265                             &req, sizeof (req)) == 0)
 266                 return 0;
 267         }
 268 #endif
 269         default:
 270             errno = EAFNOSUPPORT;
 271     }
 272     msg_Err (p_this, "cannot force multicast interface %s: %m", iface);
 273     return -1;
 274 }
 275
 276
 277 static unsigned var_GetIfIndex (vlc_object_t *obj)
 278 {
 279     char *ifname = var_InheritString (obj, "miface");
 280     if (ifname == NULL)
 281         return 0;
 282
 283     unsigned ifindex = if_nametoindex (ifname);
 284     if (ifindex == 0)
 285         msg_Err (obj, "invalid multicast interface: %s", ifname);
 286     free (ifname);
 287     return ifindex;
 288 }
 289
 290
 291 /**
 292  * IP-agnostic multicast join,
 293  * with fallback to old APIs, and fallback from SSM to ASM.
 294  */
 295 static int
 296 net_SourceSubscribe (vlc_object_t *obj, int fd,
 297                      const struct sockaddr *src, socklen_t srclen,
 298                      const struct sockaddr *grp, socklen_t grplen)
 299 {
 300 #ifdef MCAST_JOIN_SOURCE_GROUP
 301     /* Agnostic SSM multicast join */
 302     int level;
 303     struct group_source_req gsr;
 304
 305     memset (&gsr, 0, sizeof (gsr));
 306     gsr.gsr_interface = var_GetIfIndex (obj);
 307
 308     switch (grp->sa_family)
 309     {
 310 #ifdef AF_INET6
 311         case AF_INET6:
 312         {
 313             const struct sockaddr_in6 *g6 = (const struct sockaddr_in6 *)grp;
 314
 315             level = SOL_IPV6;
 316             assert (grplen >= sizeof (struct sockaddr_in6));
 317             if (g6->sin6_scope_id != 0)
 318                 gsr.gsr_interface = g6->sin6_scope_id;
 319             break;
 320         }
 321 #endif
 322         case AF_INET:
 323             level = SOL_IP;
 324             break;
 325         default:
 326             errno = EAFNOSUPPORT;
 327             return -1;
 328     }
 329
 330     assert (grplen <= sizeof (gsr.gsr_group));
 331     memcpy (&gsr.gsr_source, src, srclen);
 332     assert (srclen <= sizeof (gsr.gsr_source));
 333     memcpy (&gsr.gsr_group,  grp, grplen);
 334     if (setsockopt (fd, level, MCAST_JOIN_SOURCE_GROUP,
 335                     &gsr, sizeof (gsr)) == 0)
 336         return 0;
 337
 338 #else
 339     if (src->sa_family != grp->sa_family)
 340     {
 341         errno = EAFNOSUPPORT;
 342         return -1;
 343     }
 344
 345     switch (grp->sa_family)
 346     {
 347 # ifdef IP_ADD_SOURCE_MEMBERSHIP
 348         /* IPv4-specific API */
 349         case AF_INET:
 350         {
 351             struct ip_mreq_source imr;
 352
 353             memset (&imr, 0, sizeof (imr));
 354             assert (grplen >= sizeof (struct sockaddr_in));
 355             imr.imr_multiaddr = ((const struct sockaddr_in *)grp)->sin_addr;
 356             assert (srclen >= sizeof (struct sockaddr_in));
 357             imr.imr_sourceaddr = ((const struct sockaddr_in *)src)->sin_addr;
 358             if (setsockopt (fd, SOL_IP, IP_ADD_SOURCE_MEMBERSHIP,
 359                             &imr, sizeof (imr)) == 0)
 360                 return 0;
 361             break;
 362         }
 363 # endif
 364         default:
 365             errno = EAFNOSUPPORT;
 366     }
 367
 368 #endif
 369     msg_Err (obj, "cannot join source multicast group: %m");
 370     msg_Warn (obj, "trying ASM instead of SSM...");
 371     return net_Subscribe (obj, fd, grp, grplen);
 372 }
 373
 374
 375 int net_Subscribe (vlc_object_t *obj, int fd,
 376                    const struct sockaddr *grp, socklen_t grplen)
 377 {
 378 /* MCAST_JOIN_GROUP was introduced to OS X in v10.7, but it doesn't work,
 379  * so ignore it to use the same code as on 10.5 or 10.6 */
 380 #if defined (MCAST_JOIN_GROUP) && !defined (__APPLE__)
 381     /* Agnostic SSM multicast join */
 382     int level;
 383     struct group_req gr;
 384
 385     memset (&gr, 0, sizeof (gr));
 386     gr.gr_interface = var_GetIfIndex (obj);
 387
 388     switch (grp->sa_family)
 389     {
 390 #ifdef AF_INET6
 391         case AF_INET6:
 392         {
 393             const struct sockaddr_in6 *g6 = (const struct sockaddr_in6 *)grp;
 394
 395             level = SOL_IPV6;
 396             assert (grplen >= sizeof (struct sockaddr_in6));
 397             if (g6->sin6_scope_id != 0)
 398                 gr.gr_interface = g6->sin6_scope_id;
 399             break;
 400         }
 401 #endif
 402         case AF_INET:
 403             level = SOL_IP;
 404             break;
 405         default:
 406             errno = EAFNOSUPPORT;
 407             return -1;
 408     }
 409
 410     assert (grplen <= sizeof (gr.gr_group));
 411     memcpy (&gr.gr_group, grp, grplen);
 412     if (setsockopt (fd, level, MCAST_JOIN_GROUP, &gr, sizeof (gr)) == 0)
 413         return 0;
 414
 415 #else
 416     switch (grp->sa_family)
 417     {
 418 # ifdef IPV6_JOIN_GROUP
 419         case AF_INET6:
 420         {
 421             struct ipv6_mreq ipv6mr;
 422             const struct sockaddr_in6 *g6 = (const struct sockaddr_in6 *)grp;
 423
 424             memset (&ipv6mr, 0, sizeof (ipv6mr));
 425             assert (grplen >= sizeof (struct sockaddr_in6));
 426             ipv6mr.ipv6mr_multiaddr = g6->sin6_addr;
 427             ipv6mr.ipv6mr_interface = g6->sin6_scope_id;
 428             if (!setsockopt (fd, SOL_IPV6, IPV6_JOIN_GROUP,
 429                              &ipv6mr, sizeof (ipv6mr)))
 430                 return 0;
 431             break;
 432         }
 433 # endif
 434 # ifdef IP_ADD_MEMBERSHIP
 435         case AF_INET:
 436         {
 437             struct ip_mreq imr;
 438
 439             memset (&imr, 0, sizeof (imr));
 440             assert (grplen >= sizeof (struct sockaddr_in));
 441             imr.imr_multiaddr = ((const struct sockaddr_in *)grp)->sin_addr;
 442             if (setsockopt (fd, SOL_IP, IP_ADD_MEMBERSHIP,
 443                             &imr, sizeof (imr)) == 0)
 444                 return 0;
 445             break;
 446         }
 447 # endif
 448         default:
 449             errno = EAFNOSUPPORT;
 450     }
 451
 452 #endif
 453     msg_Err (obj, "cannot join multicast group: %m");
 454     return -1;
 455 }
 456
 457
 458 static int net_SetDSCP( int fd, uint8_t dscp )
 459 {
 460     struct sockaddr_storage addr;
 461     if( getsockname( fd, (struct sockaddr *)&addr, &(socklen_t){ sizeof (addr) }) )
 462         return -1;
 463
 464     int level, cmd;
 465
 466     switch( addr.ss_family )
 467     {
 468 #ifdef IPV6_TCLASS
 469         case AF_INET6:
 470             level = SOL_IPV6;
 471             cmd = IPV6_TCLASS;
 472             break;
 473 #endif
 474
 475         case AF_INET:
 476             level = SOL_IP;
 477             cmd = IP_TOS;
 478             break;
 479
 480         default:
 481 #ifdef ENOPROTOOPT
 482             errno = ENOPROTOOPT;
 483 #endif
 484             return -1;
 485     }
 486
 487     return setsockopt( fd, level, cmd, &(int){ dscp }, sizeof (int));
 488 }
 489
 490 #undef net_ConnectDgram
 491 /*****************************************************************************
 492  * net_ConnectDgram:
 493  *****************************************************************************
 494  * Open a datagram socket to send data to a defined destination, with an
 495  * optional hop limit.
 496  *****************************************************************************/
 497 int net_ConnectDgram( vlc_object_t *p_this, const char *psz_host, int i_port,
 498                       int i_hlim, int proto )
 499 {
 500     struct addrinfo hints = {
 501         .ai_socktype = SOCK_DGRAM,
 502         .ai_protocol = proto,
 503         .ai_flags = AI_NUMERICSERV | AI_IDN,
 504     }, *res;
 505     int       i_handle = -1;
 506     bool      b_unreach = false;
 507
 508     if( i_hlim < 0 )
 509         i_hlim = var_InheritInteger( p_this, "ttl" );
 510
 511     msg_Dbg( p_this, "net: connecting to [%s]:%d", psz_host, i_port );
 512
 513     int val = vlc_getaddrinfo (psz_host, i_port, &hints, &res);
 514     if (val)
 515     {
 516         msg_Err (p_this, "cannot resolve [%s]:%d : %s", psz_host, i_port,
 517                  gai_strerror (val));
 518         return -1;
 519     }
 520
 521     for (struct addrinfo *ptr = res; ptr != NULL; ptr = ptr->ai_next)
 522     {
 523         char *str;
 524         int fd = net_Socket (p_this, ptr->ai_family, ptr->ai_socktype,
 525                              ptr->ai_protocol);
 526         if (fd == -1)
 527             continue;
 528
 529         /* Increase the receive buffer size to 1/2MB (8Mb/s during 1/2s)
 530         * to avoid packet loss caused by scheduling problems */
 531         setsockopt (fd, SOL_SOCKET, SO_RCVBUF, &(int){ 0x80000 }, sizeof (int));
 532         setsockopt (fd, SOL_SOCKET, SO_SNDBUF, &(int){ 0x80000 }, sizeof (int));
 533
 534         /* Allow broadcast sending */
 535         setsockopt (fd, SOL_SOCKET, SO_BROADCAST, &(int){ 1 }, sizeof (int));
 536
 537         if( i_hlim >= 0 )
 538             net_SetMcastHopLimit( p_this, fd, ptr->ai_family, i_hlim );
 539
 540         str = var_InheritString (p_this, "miface");
 541         if (str != NULL)
 542         {
 543             net_SetMcastOut (p_this, fd, ptr->ai_family, str);
 544             free (str);
 545         }
 546
 547         net_SetDSCP (fd, var_InheritInteger (p_this, "dscp"));
 548
 549         if( connect( fd, ptr->ai_addr, ptr->ai_addrlen ) == 0 )
 550         {
 551             /* success */
 552             i_handle = fd;
 553             break;
 554         }
 555
 556 #if defined( WIN32 )
 557         if( WSAGetLastError () == WSAENETUNREACH )
 558 #else
 559         if( errno == ENETUNREACH )
 560 #endif
 561             b_unreach = true;
 562         else
 563         {
 564             msg_Warn( p_this, "%s port %d : %m", psz_host, i_port);
 565             net_Close( fd );
 566             continue;
 567         }
 568     }
 569
 570     freeaddrinfo( res );
 571
 572     if( i_handle == -1 )
 573     {
 574         if( b_unreach )
 575             msg_Err( p_this, "Host %s port %d is unreachable", psz_host,
 576                      i_port );
 577         return -1;
 578     }
 579
 580     return i_handle;
 581 }
 582
 583 #undef net_OpenDgram
 584 /*****************************************************************************
 585  * net_OpenDgram:
 586  *****************************************************************************
 587  * OpenDgram a datagram socket and return a handle
 588  *****************************************************************************/
 589 int net_OpenDgram( vlc_object_t *obj, const char *psz_bind, int i_bind,
 590                    const char *psz_server, int i_server, int protocol )
 591 {
 592     if ((psz_server == NULL) || (psz_server[0] == '\0'))
 593         return net_ListenSingle (obj, psz_bind, i_bind, protocol);
 594
 595     msg_Dbg (obj, "net: connecting to [%s]:%d from [%s]:%d",
 596              psz_server, i_server, psz_bind, i_bind);
 597
 598     struct addrinfo hints = {
 599         .ai_socktype = SOCK_DGRAM,
 600         .ai_protocol = protocol,
 601         .ai_flags = AI_NUMERICSERV | AI_IDN,
 602     }, *loc, *rem;
 603
 604     int val = vlc_getaddrinfo (psz_server, i_server, &hints, &rem);
 605     if (val)
 606     {
 607         msg_Err (obj, "cannot resolve %s port %d : %s", psz_bind, i_bind,
 608                  gai_strerror (val));
 609         return -1;
 610     }
 611
 612     hints.ai_flags |= AI_PASSIVE;
 613     val = vlc_getaddrinfo (psz_bind, i_bind, &hints, &loc);
 614     if (val)
 615     {
 616         msg_Err (obj, "cannot resolve %s port %d : %s", psz_bind, i_bind,
 617                  gai_strerror (val));
 618         freeaddrinfo (rem);
 619         return -1;
 620     }
 621
 622     val = -1;
 623     for (struct addrinfo *ptr = loc; ptr != NULL; ptr = ptr->ai_next)
 624     {
 625         int fd = net_Socket (obj, ptr->ai_family, ptr->ai_socktype,
 626                              ptr->ai_protocol);
 627         if (fd == -1)
 628             continue; // usually, address family not supported
 629
 630         fd = net_SetupDgramSocket( obj, fd, ptr );
 631         if( fd == -1 )
 632             continue;
 633
 634         for (struct addrinfo *ptr2 = rem; ptr2 != NULL; ptr2 = ptr2->ai_next)
 635         {
 636             if ((ptr2->ai_family != ptr->ai_family)
 637              || (ptr2->ai_socktype != ptr->ai_socktype)
 638              || (ptr2->ai_protocol != ptr->ai_protocol))
 639                 continue;
 640
 641             if (net_SockAddrIsMulticast (ptr->ai_addr, ptr->ai_addrlen)
 642               ? net_SourceSubscribe (obj, fd,
 643                                      ptr2->ai_addr, ptr2->ai_addrlen,
 644                                      ptr->ai_addr, ptr->ai_addrlen)
 645               : connect (fd, ptr2->ai_addr, ptr2->ai_addrlen))
 646             {
 647                 msg_Err (obj, "cannot connect to %s port %d: %m",
 648                          psz_server, i_server);
 649                 continue;
 650             }
 651             val = fd;
 652             break;
 653         }
 654
 655         if (val != -1)
 656             break;
 657
 658         net_Close (fd);
 659     }
 660
 661     freeaddrinfo (rem);
 662     freeaddrinfo (loc);
 663     return val;
 664 }
 665
 666
 667 /**
 668  * net_SetCSCov:
 669  * Sets the send and receive checksum coverage of a socket:
 670  * @param fd socket
 671  * @param sendcov payload coverage of sent packets (bytes), -1 for full
 672  * @param recvcov minimum payload coverage of received packets, -1 for full
 673  */
 674 int net_SetCSCov (int fd, int sendcov, int recvcov)
 675 {
 676     int type;
 677
 678     if (getsockopt (fd, SOL_SOCKET, SO_TYPE,
 679                     &type, &(socklen_t){ sizeof (type) }))
 680         return VLC_EGENERIC;
 681
 682     switch (type)
 683     {
 684 #ifdef UDPLITE_RECV_CSCOV
 685         case SOCK_DGRAM: /* UDP-Lite */
 686             if (sendcov == -1)
 687                 sendcov = 0;
 688             else
 689                 sendcov += 8; /* partial */
 690             if (setsockopt (fd, SOL_UDPLITE, UDPLITE_SEND_CSCOV, &sendcov,
 691                             sizeof (sendcov)))
 692                 return VLC_EGENERIC;
 693
 694             if (recvcov == -1)
 695                 recvcov = 0;
 696             else
 697                 recvcov += 8;
 698             if (setsockopt (fd, SOL_UDPLITE, UDPLITE_RECV_CSCOV,
 699                             &recvcov, sizeof (recvcov)))
 700                 return VLC_EGENERIC;
 701
 702             return VLC_SUCCESS;
 703 #endif
 704 #ifdef DCCP_SOCKOPT_SEND_CSCOV
 705         case SOCK_DCCP: /* DCCP and its ill-named socket type */
 706             if ((sendcov == -1) || (sendcov > 56))
 707                 sendcov = 0;
 708             else
 709                 sendcov = (sendcov + 3) / 4;
 710             if (setsockopt (fd, SOL_DCCP, DCCP_SOCKOPT_SEND_CSCOV,
 711                             &sendcov, sizeof (sendcov)))
 712                 return VLC_EGENERIC;
 713
 714             if ((recvcov == -1) || (recvcov > 56))
 715                 recvcov = 0;
 716             else
 717                 recvcov = (recvcov + 3) / 4;
 718             if (setsockopt (fd, SOL_DCCP, DCCP_SOCKOPT_RECV_CSCOV,
 719                             &recvcov, sizeof (recvcov)))
 720                 return VLC_EGENERIC;
 721
 722             return VLC_SUCCESS;
 723 #endif
 724     }
 725 #if !defined( UDPLITE_RECV_CSCOV ) && !defined( DCCP_SOCKOPT_SEND_CSCOV )
 726     VLC_UNUSED(sendcov);
 727     VLC_UNUSED(recvcov);
 728 #endif
 729
 730     return VLC_EGENERIC;
 731 }