git.sesse.net Git - vlc/blob - src/stream_output/sap.c

   1 /*****************************************************************************
   2  * sap.c : SAP announce handler
   3  *****************************************************************************
   4  * Copyright (C) 2002-2005 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Clément Stenac <zorglub@videolan.org>
   8  *          Rémi Denis-Courmont <rem # videolan.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  23  *****************************************************************************/
  24
  25 /*****************************************************************************
  26  * Preamble
  27  *****************************************************************************/
  28
  29 #include <vlc/vlc.h>
  30
  31 #include <stdlib.h>                                                /* free() */
  32 #include <stdio.h>                                              /* sprintf() */
  33 #include <string.h>                                            /* strerror() */
  34 #include <ctype.h>                                  /* tolower(), isxdigit() */
  35
  36 #include <vlc/sout.h>
  37
  38 #include "network.h"
  39 #include "charset.h"
  40
  41 /* SAP is always on that port */
  42 #define SAP_PORT 9875
  43
  44 #define DEFAULT_PORT "1234"
  45
  46 #undef EXTRA_DEBUG
  47
  48 /* SAP Specific structures */
  49
  50 /* 100ms */
  51 #define SAP_IDLE ((mtime_t)(0.100*CLOCK_FREQ))
  52 #define SAP_MAX_BUFFER 65534
  53 #define MIN_INTERVAL 2
  54 #define MAX_INTERVAL 300
  55
  56 /* A SAP announce address. For each of these, we run the
  57  * control flow algorithm */
  58 struct sap_address_t
  59 {
  60     char *psz_address;
  61     char psz_machine[NI_MAXNUMERICHOST];
  62     int i_rfd; /* Read socket */
  63     int i_wfd; /* Write socket */
  64
  65     /* Used for flow control */
  66     mtime_t t1;
  67     vlc_bool_t b_enabled;
  68     vlc_bool_t b_ready;
  69     int i_interval;
  70     int i_buff;
  71     int i_limit;
  72 };
  73
  74 /*****************************************************************************
  75  * Local prototypes
  76  *****************************************************************************/
  77 static void RunThread( vlc_object_t *p_this);
  78 static int CalculateRate( sap_handler_t *p_sap, sap_address_t *p_address );
  79 static char *SDPGenerate( sap_handler_t *p_sap,
  80                           const session_descriptor_t *p_session,
  81                           const sap_address_t *p_addr, vlc_bool_t b_ssm );
  82
  83 static int announce_SendSAPAnnounce( sap_handler_t *p_sap,
  84                                      sap_session_t *p_session );
  85
  86
  87 static int announce_SAPAnnounceAdd( sap_handler_t *p_sap,
  88                              session_descriptor_t *p_session );
  89
  90 static int announce_SAPAnnounceDel( sap_handler_t *p_sap,
  91                              session_descriptor_t *p_session );
  92
  93
  94 /**
  95  * Create the SAP handler
  96  *
  97  * \param p_announce the parent announce_handler
  98  * \return the newly created SAP handler or NULL on error
  99  */
 100 sap_handler_t *announce_SAPHandlerCreate( announce_handler_t *p_announce )
 101 {
 102     sap_handler_t *p_sap;
 103
 104     p_sap = vlc_object_create( p_announce, sizeof( sap_handler_t ) );
 105
 106     if( !p_sap )
 107     {
 108         msg_Err( p_announce, "out of memory" );
 109         return NULL;
 110     }
 111
 112     vlc_mutex_init( p_sap, &p_sap->object_lock );
 113
 114     p_sap->pf_add = announce_SAPAnnounceAdd;
 115     p_sap->pf_del = announce_SAPAnnounceDel;
 116
 117     p_sap->i_sessions = 0;
 118     p_sap->i_addresses = 0;
 119     p_sap->i_current_session = 0;
 120
 121     p_sap->b_control = config_GetInt( p_sap, "sap-flow-control");
 122
 123     if( vlc_thread_create( p_sap, "sap handler", RunThread,
 124                        VLC_THREAD_PRIORITY_LOW, VLC_FALSE ) )
 125     {
 126         msg_Dbg( p_announce, "unable to spawn SAP handler thread");
 127         free( p_sap );
 128         return NULL;
 129     };
 130     msg_Dbg( p_announce, "thread created, %i sessions", p_sap->i_sessions);
 131     return p_sap;
 132 }
 133
 134 /**
 135  *  Destroy the SAP handler
 136  *  \param p_this the SAP Handler to destroy
 137  *  \return nothing
 138  */
 139 void announce_SAPHandlerDestroy( sap_handler_t *p_sap )
 140 {
 141     int i;
 142
 143     vlc_mutex_destroy( &p_sap->object_lock );
 144
 145     /* Free the remaining sessions */
 146     for( i = 0 ; i< p_sap->i_sessions ; i++)
 147     {
 148         sap_session_t *p_session = p_sap->pp_sessions[i];
 149         FREENULL( p_session->psz_sdp );
 150         FREENULL( p_session->psz_data );
 151         REMOVE_ELEM( p_sap->pp_sessions, p_sap->i_sessions , i );
 152         FREENULL( p_session );
 153     }
 154
 155     /* Free the remaining addresses */
 156     for( i = 0 ; i< p_sap->i_addresses ; i++)
 157     {
 158         sap_address_t *p_address = p_sap->pp_addresses[i];
 159         FREENULL( p_address->psz_address );
 160         if( p_address->i_rfd > -1 )
 161         {
 162             net_Close( p_address->i_rfd );
 163         }
 164         if( p_address->i_wfd > -1 && p_sap->b_control )
 165         {
 166             net_Close( p_address->i_wfd );
 167         }
 168         REMOVE_ELEM( p_sap->pp_addresses, p_sap->i_addresses, i );
 169         FREENULL( p_address );
 170     }
 171
 172     /* Free the structure */
 173     vlc_object_destroy( p_sap );
 174 }
 175
 176 /**
 177  * main SAP handler thread
 178  * \param p_this the SAP Handler object
 179  * \return nothing
 180  */
 181 static void RunThread( vlc_object_t *p_this)
 182 {
 183     sap_handler_t *p_sap = (sap_handler_t*)p_this;
 184     sap_session_t *p_session;
 185
 186     while( !p_sap->b_die )
 187     {
 188         int i;
 189
 190         /* If needed, get the rate info */
 191         if( p_sap->b_control == VLC_TRUE )
 192         {
 193             for( i = 0 ; i< p_sap->i_addresses ; i++)
 194             {
 195                 if( p_sap->pp_addresses[i]->b_enabled == VLC_TRUE )
 196                 {
 197                     CalculateRate( p_sap, p_sap->pp_addresses[i] );
 198                 }
 199             }
 200         }
 201
 202         /* Find the session to announce */
 203         vlc_mutex_lock( &p_sap->object_lock );
 204         if( p_sap->i_sessions > p_sap->i_current_session + 1)
 205         {
 206             p_sap->i_current_session++;
 207         }
 208         else if( p_sap->i_sessions > 0)
 209         {
 210             p_sap->i_current_session = 0;
 211         }
 212         else
 213         {
 214             vlc_mutex_unlock( &p_sap->object_lock );
 215             msleep( SAP_IDLE );
 216             continue;
 217         }
 218         p_session = p_sap->pp_sessions[p_sap->i_current_session];
 219         vlc_mutex_unlock( &p_sap->object_lock );
 220
 221         /* And announce it */
 222         if( p_session->p_address->b_enabled == VLC_TRUE &&
 223             p_session->p_address->b_ready == VLC_TRUE )
 224         {
 225             announce_SendSAPAnnounce( p_sap, p_session );
 226         }
 227
 228         msleep( SAP_IDLE );
 229     }
 230 }
 231
 232 /* Add a SAP announce */
 233 static int announce_SAPAnnounceAdd( sap_handler_t *p_sap,
 234                              session_descriptor_t *p_session )
 235 {
 236     int i_header_size, i;
 237     char *psz_head, psz_addr[NI_MAXNUMERICHOST];
 238     vlc_bool_t b_ipv6 = VLC_FALSE, b_ssm = VLC_FALSE;
 239     sap_session_t *p_sap_session;
 240     mtime_t i_hash;
 241     struct addrinfo hints, *res;
 242     struct sockaddr_storage addr;
 243     socklen_t addrlen;
 244
 245     vlc_mutex_lock( &p_sap->object_lock );
 246
 247     if( p_session->psz_uri == NULL )
 248     {
 249         vlc_mutex_unlock( &p_sap->object_lock );
 250         msg_Err( p_sap, "*FIXME* unexpected NULL URI for SAP announce" );
 251         msg_Err( p_sap, "This should not happen. VLC needs fixing." );
 252         return VLC_EGENERIC;
 253     }
 254
 255     /* Determine SAP multicast address automatically */
 256     memset( &hints, 0, sizeof( hints ) );
 257     hints.ai_socktype = SOCK_DGRAM;
 258     hints.ai_flags = AI_NUMERICHOST;
 259
 260     i = vlc_getaddrinfo( (vlc_object_t *)p_sap, p_session->psz_uri, 0,
 261                          &hints, &res );
 262     if( i )
 263     {
 264         vlc_mutex_unlock( &p_sap->object_lock );
 265         msg_Err( p_sap, "Invalid URI for SAP announce: %s: %s",
 266                  p_session->psz_uri, vlc_gai_strerror( i ) );
 267         return VLC_EGENERIC;
 268     }
 269
 270     addrlen = res->ai_addrlen;
 271     if ((unsigned)addrlen > sizeof (addr))
 272     {
 273         vlc_mutex_unlock( &p_sap->object_lock );
 274         vlc_freeaddrinfo( res );
 275         msg_Err( p_sap, "Unsupported address family of size %d > %u",
 276                  res->ai_addrlen, (unsigned) sizeof( addr ) );
 277         return VLC_EGENERIC;
 278     }
 279
 280     memcpy (&addr, res->ai_addr, addrlen);
 281     vlc_freeaddrinfo (res);
 282
 283     switch( addr.ss_family )
 284     {
 285 #if defined (HAVE_INET_PTON) || defined (WIN32)
 286         case AF_INET6:
 287         {
 288             /* See RFC3513 for list of valid IPv6 scopes */
 289             struct in6_addr *a6 = &((struct sockaddr_in6 *)&addr)->sin6_addr;
 290
 291             memcpy( a6->s6_addr + 2, "\x00\x00\x00\x00\x00\x00"
 292                    "\x00\x00\x00\x00\x00\x02\x7f\xfe", 14 );
 293             if( IN6_IS_ADDR_MULTICAST( a6 ) )
 294             {
 295                 /* force flags to zero, preserve scope */
 296                 a6->s6_addr[1] &= 0xf;
 297
 298                 /* SSM <=> ff3x::/32 */
 299                 b_ssm = (GetDWLE (a6->s6_addr) & 0xfff0ffff) == 0xff300000;
 300             }
 301             else
 302                 /* Unicast IPv6 - assume global scope */
 303                 memcpy( a6->s6_addr, "\xff\x0e", 2 );
 304
 305             b_ipv6 = VLC_TRUE;
 306             break;
 307         }
 308 #endif
 309
 310         case AF_INET:
 311         {
 312             /* See RFC2365 for IPv4 scopes */
 313             uint32_t ipv4;
 314
 315             ipv4 = ntohl( ((struct sockaddr_in *)&addr)->sin_addr.s_addr );
 316             /* 224.0.0.0/24 => 224.0.0.255 */
 317             if ((ipv4 & 0xffffff00) == 0xe0000000)
 318                 ipv4 =  0xe00000ff;
 319             else
 320             /* 239.255.0.0/16 => 239.255.255.255 */
 321             if ((ipv4 & 0xffff0000) == 0xefff0000)
 322                 ipv4 =  0xefffffff;
 323             else
 324             /* 239.192.0.0/14 => 239.195.255.255 */
 325             if ((ipv4 & 0xfffc0000) == 0xefc00000)
 326                 ipv4 =  0xefc3ffff;
 327             else
 328             if ((ipv4 & 0xff000000) == 0xef000000)
 329                 ipv4 = 0;
 330             else
 331             /* other addresses => 224.2.127.254 */
 332             {
 333                 ipv4 = 0xe0027ffe;
 334
 335                 /* SSM: 232.0.0.0/8 */
 336                 b_ssm = (ipv4 >> 24) == 232;
 337             }
 338
 339             if( ipv4 == 0 )
 340             {
 341                 msg_Err( p_sap, "Out-of-scope multicast address "
 342                         "not supported by SAP: %s", p_session->psz_uri );
 343                 vlc_mutex_unlock( &p_sap->object_lock );
 344                 return VLC_EGENERIC;
 345             }
 346
 347             ((struct sockaddr_in *)&addr)->sin_addr.s_addr = htonl( ipv4 );
 348             break;
 349         }
 350
 351         default:
 352             vlc_mutex_unlock( &p_sap->object_lock );
 353             msg_Err( p_sap, "Address family %d not supported by SAP",
 354                      addr.ss_family );
 355             return VLC_EGENERIC;
 356     }
 357
 358     i = vlc_getnameinfo( (struct sockaddr *)&addr, addrlen,
 359                          psz_addr, sizeof( psz_addr ), NULL, NI_NUMERICHOST );
 360
 361     if( i )
 362     {
 363         vlc_mutex_unlock( &p_sap->object_lock );
 364         msg_Err( p_sap, "%s", vlc_gai_strerror( i ) );
 365         return VLC_EGENERIC;
 366     }
 367
 368     msg_Dbg( p_sap, "using SAP address: %s", psz_addr);
 369
 370     /* XXX: Check for dupes */
 371     p_sap_session = (sap_session_t*)malloc(sizeof(sap_session_t));
 372     p_sap_session->p_address = NULL;
 373
 374     /* Add the address to the buffer */
 375     for( i = 0; i < p_sap->i_addresses; i++)
 376     {
 377         if( !strcmp( psz_addr, p_sap->pp_addresses[i]->psz_address ) )
 378         {
 379             p_sap_session->p_address = p_sap->pp_addresses[i];
 380             break;
 381         }
 382     }
 383
 384     if( p_sap_session->p_address == NULL )
 385     {
 386         sap_address_t *p_address = (sap_address_t *)
 387                                     malloc( sizeof(sap_address_t) );
 388         if( !p_address )
 389         {
 390             msg_Err( p_sap, "out of memory" );
 391             return VLC_ENOMEM;
 392         }
 393         p_address->psz_address = strdup( psz_addr );
 394         p_address->i_wfd = net_ConnectUDP( p_sap, psz_addr, SAP_PORT, 255 );
 395         if( p_address->i_wfd != -1 )
 396         {
 397             char *ptr;
 398
 399             net_StopRecv( p_address->i_wfd );
 400             net_GetSockAddress( p_address->i_wfd, p_address->psz_machine,
 401                                 NULL );
 402
 403             /* removes scope if present */
 404             ptr = strchr( p_address->psz_machine, '%' );
 405             if( ptr != NULL )
 406                 *ptr = '\0';
 407         }
 408
 409         if( p_sap->b_control == VLC_TRUE )
 410         {
 411             p_address->i_rfd = net_ListenUDP1( (vlc_object_t*)p_sap, psz_addr, SAP_PORT );
 412             if( p_address->i_rfd != -1 )
 413                 net_StopSend( p_address->i_rfd );
 414             p_address->i_buff = 0;
 415             p_address->b_enabled = VLC_TRUE;
 416             p_address->b_ready = VLC_FALSE;
 417             p_address->i_limit = 10000; /* 10000 bps */
 418             p_address->t1 = 0;
 419         }
 420         else
 421         {
 422             p_address->b_enabled = VLC_TRUE;
 423             p_address->b_ready = VLC_TRUE;
 424             p_address->i_interval = config_GetInt( p_sap,"sap-interval");
 425             p_address->i_rfd = -1;
 426         }
 427
 428         if( p_address->i_wfd == -1 || (p_address->i_rfd == -1
 429                                         && p_sap->b_control ) )
 430         {
 431             msg_Warn( p_sap, "disabling address" );
 432             p_address->b_enabled = VLC_FALSE;
 433         }
 434
 435         INSERT_ELEM( p_sap->pp_addresses,
 436                      p_sap->i_addresses,
 437                      p_sap->i_addresses,
 438                      p_address );
 439         p_sap_session->p_address = p_address;
 440     }
 441
 442
 443     /* Build the SAP Headers */
 444     i_header_size = ( b_ipv6 ? 16 : 4 ) + 20;
 445     psz_head = (char *) malloc( i_header_size * sizeof( char ) );
 446     if( psz_head == NULL )
 447     {
 448         msg_Err( p_sap, "out of memory" );
 449         return VLC_ENOMEM;
 450     }
 451
 452     /* SAPv1, not encrypted, not compressed */
 453     psz_head[0] = b_ipv6 ? 0x30 : 0x20;
 454     psz_head[1] = 0x00; /* No authentification length */
 455
 456     i_hash = mdate();
 457     psz_head[2] = (i_hash & 0xFF00) >> 8; /* Msg id hash */
 458     psz_head[3] = (i_hash & 0xFF);        /* Msg id hash 2 */
 459
 460 #if defined (HAVE_INET_PTON) || defined (WIN32)
 461     if( b_ipv6 )
 462     {
 463         inet_pton( AF_INET6, /* can't fail */
 464                    p_sap_session->p_address->psz_machine,
 465                    psz_head + 4 );
 466     }
 467     else
 468 #endif
 469     {
 470         inet_pton( AF_INET, /* can't fail */
 471                    p_sap_session->p_address->psz_machine,
 472                    psz_head + 4 );
 473     }
 474
 475     memcpy( psz_head + (b_ipv6 ? 20 : 8), "application/sdp", 15 );
 476
 477     /* If needed, build the SDP */
 478     if( p_session->psz_sdp == NULL )
 479     {
 480         p_session->psz_sdp = SDPGenerate( p_sap, p_session,
 481                                           p_sap_session->p_address, b_ssm );
 482         if( p_session->psz_sdp == NULL )
 483         {
 484             vlc_mutex_unlock( &p_sap->object_lock );
 485             return VLC_ENOMEM;
 486         }
 487     }
 488
 489     p_sap_session->psz_sdp = strdup( p_session->psz_sdp );
 490     p_sap_session->i_last = 0;
 491
 492     psz_head[ i_header_size-1 ] = '\0';
 493     p_sap_session->i_length = i_header_size + strlen( p_sap_session->psz_sdp);
 494
 495     p_sap_session->psz_data = (uint8_t *)malloc( sizeof(char)*
 496                                                  p_sap_session->i_length );
 497
 498     /* Build the final message */
 499     memcpy( p_sap_session->psz_data, psz_head, i_header_size );
 500     memcpy( p_sap_session->psz_data+i_header_size, p_sap_session->psz_sdp,
 501             strlen( p_sap_session->psz_sdp) );
 502
 503     free( psz_head );
 504
 505     /* Enqueue the announce */
 506     INSERT_ELEM( p_sap->pp_sessions,
 507                  p_sap->i_sessions,
 508                  p_sap->i_sessions,
 509                  p_sap_session );
 510     msg_Dbg( p_sap,"%i addresses, %i sessions",
 511                    p_sap->i_addresses,p_sap->i_sessions);
 512
 513     /* Remember the SAP session for later deletion */
 514     p_session->p_sap = p_sap_session;
 515
 516     vlc_mutex_unlock( &p_sap->object_lock );
 517
 518     return VLC_SUCCESS;
 519 }
 520
 521 /* Remove a SAP Announce */
 522 static int announce_SAPAnnounceDel( sap_handler_t *p_sap,
 523                              session_descriptor_t *p_session )
 524 {
 525     int i;
 526     vlc_mutex_lock( &p_sap->object_lock );
 527
 528     msg_Dbg( p_sap,"removing SAP announce %p",p_session->p_sap);
 529
 530     /* Dequeue the announce */
 531     for( i = 0; i< p_sap->i_sessions; i++)
 532     {
 533         if( p_session->p_sap == p_sap->pp_sessions[i] )
 534         {
 535             REMOVE_ELEM( p_sap->pp_sessions,
 536                          p_sap->i_sessions,
 537                          i );
 538
 539             FREENULL( p_session->p_sap->psz_sdp );
 540             FREENULL( p_session->p_sap->psz_data );
 541             free( p_session->p_sap );
 542             break;
 543         }
 544     }
 545
 546     /* XXX: Dequeue the address too if it is not used anymore
 547      * TODO: - address refcount
 548              - send a SAP deletion packet */
 549
 550     msg_Dbg( p_sap,"%i announcements remaining", p_sap->i_sessions );
 551
 552     vlc_mutex_unlock( &p_sap->object_lock );
 553
 554     return VLC_SUCCESS;
 555 }
 556
 557 static int announce_SendSAPAnnounce( sap_handler_t *p_sap,
 558                                      sap_session_t *p_session )
 559 {
 560     int i_ret;
 561
 562     /* This announce has never been sent yet */
 563     if( p_session->i_last == 0 )
 564     {
 565         p_session->i_next = mdate()+ p_session->p_address->i_interval*1000000;
 566         p_session->i_last = 1;
 567         return VLC_SUCCESS;
 568     }
 569
 570     if( p_session->i_next < mdate() )
 571     {
 572 #ifdef EXTRA_DEBUG
 573         msg_Dbg( p_sap, "sending announce");
 574 #endif
 575         i_ret = net_Write( p_sap, p_session->p_address->i_wfd, NULL,
 576                            p_session->psz_data,
 577                            p_session->i_length );
 578         if( i_ret != (int)p_session->i_length )
 579         {
 580             msg_Warn( p_sap, "SAP send failed on address %s (%i %i)",
 581                       p_session->p_address->psz_address,
 582                       i_ret, p_session->i_length );
 583         }
 584         p_session->i_last = p_session->i_next;
 585         p_session->i_next = p_session->i_last
 586                             + p_session->p_address->i_interval*1000000;
 587     }
 588     else
 589     {
 590         return VLC_SUCCESS;
 591     }
 592     return VLC_SUCCESS;
 593 }
 594
 595 static char *SDPGenerate( sap_handler_t *p_sap,
 596                           const session_descriptor_t *p_session,
 597                           const sap_address_t *p_addr, vlc_bool_t b_ssm )
 598 {
 599     int64_t i_sdp_id = mdate();
 600     int     i_sdp_version = 1 + p_sap->i_sessions + (rand()&0xfff);
 601     char *psz_group, *psz_name, psz_uribuf[NI_MAXNUMERICHOST], *psz_uri,
 602          *psz_sdp;
 603     char ipv;
 604
 605     psz_group = p_session->psz_group;
 606     psz_name = p_session->psz_name;
 607
 608     /* FIXME: really check that psz_uri is a real IP address
 609      * FIXME: make a common function to obtain a canonical IP address */
 610     ipv = ( strchr( p_session->psz_uri, ':' )  != NULL) ? '6' : '4';
 611     if( *p_session->psz_uri == '[' )
 612     {
 613         char *ptr;
 614
 615         strlcpy( psz_uribuf, p_session->psz_uri + 1, sizeof( psz_uribuf ) );
 616         ptr = strchr( psz_uribuf, '%' );
 617         if( ptr != NULL)
 618             *ptr = '\0';
 619         ptr = strchr( psz_uribuf, ']' );
 620         if( ptr != NULL)
 621             *ptr = '\0';
 622         psz_uri = psz_uribuf;
 623     }
 624     else
 625         psz_uri = p_session->psz_uri;
 626
 627     char *sfilter = NULL;
 628     if (b_ssm)
 629     {
 630         if (asprintf (&sfilter, "a=source-filter: incl IN IP%c * %s\r\n",
 631                       ipv, p_addr->psz_machine) == -1)
 632             return NULL;
 633     }
 634
 635     /* see the lists in modules/stream_out/rtp.c for compliance stuff */
 636     int res = asprintf (&psz_sdp,
 637                         "v=0\r\n"
 638                         "o=- "I64Fd" %d IN IP%c %s\r\n"
 639                         "s=%s\r\n"
 640                         "c=IN IP%c %s/%d\r\n"
 641                         "t=0 0\r\n"
 642                         "a=tool:"PACKAGE_STRING"\r\n"
 643                         "a=recvonly\r\n"
 644                         "a=type:broadcast\n"
 645                         "%s"
 646                         "m=video %d %s %d\r\n"
 647                         "%s%s%s",
 648                         i_sdp_id, i_sdp_version,
 649                         ipv, p_addr->psz_machine,
 650                         psz_name, ipv, psz_uri,
 651                         (p_session->i_ttl != -1) ? p_session->i_ttl : 255,
 652                         (sfilter != NULL) ? sfilter : "",
 653                         p_session->i_port,
 654                         p_session->b_rtp ? "RTP/AVP" : "udp",
 655                         p_session->i_payload,
 656                         psz_group ? "a=x-plgroup:" : "",
 657                         psz_group ? psz_group : "", psz_group ? "\r\n" : "");
 658     if (sfilter != NULL)
 659         free (sfilter);
 660
 661     if (res == -1)
 662         return NULL;
 663
 664     msg_Dbg( p_sap, "Generated SDP (%i bytes):\n%s", strlen(psz_sdp),
 665              psz_sdp );
 666     return psz_sdp;
 667 }
 668
 669 static int CalculateRate( sap_handler_t *p_sap, sap_address_t *p_address )
 670 {
 671     int i_read;
 672     uint8_t buffer[SAP_MAX_BUFFER];
 673     int i_tot = 0;
 674     mtime_t i_temp;
 675     int i_rate;
 676
 677     if( p_address->t1 == 0 )
 678     {
 679         p_address->t1 = mdate();
 680         return VLC_SUCCESS;
 681     }
 682     do
 683     {
 684         /* Might be too slow if we have huge data */
 685         i_read = net_ReadNonBlock( p_sap, p_address->i_rfd, NULL, buffer,
 686                                    SAP_MAX_BUFFER, 0 );
 687         i_tot += i_read;
 688     } while( i_read > 0 );
 689
 690     i_temp = mdate();
 691
 692     /* We calculate the rate every 5 seconds */
 693     if( i_temp - p_address->t1 < 5000000 )
 694     {
 695         p_address->i_buff += i_tot;
 696         return VLC_SUCCESS;
 697     }
 698
 699     /* Bits/second */
 700     i_rate = (int)(8*1000000*((mtime_t)p_address->i_buff + (mtime_t)i_tot ) /
 701                         (i_temp - p_address->t1 ));
 702
 703     p_address->i_limit = 10000;
 704
 705     p_address->i_interval = ((1000*i_rate / p_address->i_limit) *
 706                             (MAX_INTERVAL - MIN_INTERVAL))/1000 + MIN_INTERVAL;
 707
 708     if( p_address->i_interval > MAX_INTERVAL || p_address->i_interval < 0 )
 709     {
 710         p_address->i_interval = MAX_INTERVAL;
 711     }
 712 #ifdef EXTRA_DEBUG
 713     msg_Dbg( p_sap,"%s:%i: rate=%i, interval = %i s",
 714              p_address->psz_address,SAP_PORT, i_rate, p_address->i_interval );
 715 #endif
 716
 717     p_address->b_ready = VLC_TRUE;
 718
 719     p_address->t1 = i_temp;
 720     p_address->i_buff = 0;
 721
 722     return VLC_SUCCESS;
 723 }