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 #include <vlc_network.h>
  38 #include <vlc_charset.h>
  39
  40 #include "stream_output.h"
  41
  42 /* SAP is always on that port */
  43 #define SAP_PORT 9875
  44
  45 #define DEFAULT_PORT "1234"
  46
  47 #undef EXTRA_DEBUG
  48
  49 /* SAP Specific structures */
  50
  51 /* 100ms */
  52 #define SAP_IDLE ((mtime_t)(0.100*CLOCK_FREQ))
  53 #define SAP_MAX_BUFFER 65534
  54 #define MIN_INTERVAL 2
  55 #define MAX_INTERVAL 300
  56
  57 /* A SAP announce address. For each of these, we run the
  58  * control flow algorithm */
  59 struct sap_address_t
  60 {
  61     char *psz_address;
  62     char psz_machine[NI_MAXNUMERICHOST];
  63     int i_rfd; /* Read socket */
  64     int i_wfd; /* Write socket */
  65
  66     /* Used for flow control */
  67     mtime_t t1;
  68     vlc_bool_t b_enabled;
  69     vlc_bool_t b_ready;
  70     int i_interval;
  71     int i_buff;
  72     int i_limit;
  73 };
  74
  75 /* A SAP session descriptor, enqueued in the SAP handler queue */
  76 struct sap_session_t {
  77     char          *psz_sdp;
  78     uint8_t       *psz_data;
  79     unsigned      i_length;
  80     sap_address_t *p_address;
  81     session_descriptor_t *p_sd;
  82
  83     /* Last and next send */
  84     mtime_t        i_last;
  85     mtime_t        i_next;
  86 };
  87
  88 /*****************************************************************************
  89  * Local prototypes
  90  *****************************************************************************/
  91 static void RunThread( vlc_object_t *p_this);
  92 static int CalculateRate( sap_handler_t *p_sap, sap_address_t *p_address );
  93 static char *SDPGenerate( sap_handler_t *p_sap,
  94                           const session_descriptor_t *p_session,
  95                           const sap_address_t *p_addr, vlc_bool_t b_ssm );
  96
  97 static int announce_SendSAPAnnounce( sap_handler_t *p_sap,
  98                                      sap_session_t *p_session );
  99
 100
 101 static int announce_SAPAnnounceAdd( sap_handler_t *p_sap,
 102                              session_descriptor_t *p_session );
 103
 104 static int announce_SAPAnnounceDel( sap_handler_t *p_sap,
 105                              session_descriptor_t *p_session );
 106
 107
 108 /**
 109  * Create the SAP handler
 110  *
 111  * \param p_announce the parent announce_handler
 112  * \return the newly created SAP handler or NULL on error
 113  */
 114 sap_handler_t *announce_SAPHandlerCreate( announce_handler_t *p_announce )
 115 {
 116     sap_handler_t *p_sap;
 117
 118     p_sap = vlc_object_create( p_announce, sizeof( sap_handler_t ) );
 119
 120     if( !p_sap )
 121     {
 122         msg_Err( p_announce, "out of memory" );
 123         return NULL;
 124     }
 125
 126     vlc_mutex_init( p_sap, &p_sap->object_lock );
 127
 128     p_sap->pf_add = announce_SAPAnnounceAdd;
 129     p_sap->pf_del = announce_SAPAnnounceDel;
 130
 131     p_sap->i_sessions = 0;
 132     p_sap->i_addresses = 0;
 133     p_sap->i_current_session = 0;
 134
 135     p_sap->b_control = config_GetInt( p_sap, "sap-flow-control");
 136
 137     if( vlc_thread_create( p_sap, "sap handler", RunThread,
 138                        VLC_THREAD_PRIORITY_LOW, VLC_FALSE ) )
 139     {
 140         msg_Dbg( p_announce, "unable to spawn SAP handler thread");
 141         free( p_sap );
 142         return NULL;
 143     };
 144     msg_Dbg( p_announce, "thread created, %i sessions", p_sap->i_sessions);
 145     return p_sap;
 146 }
 147
 148 /**
 149  *  Destroy the SAP handler
 150  *  \param p_this the SAP Handler to destroy
 151  *  \return nothing
 152  */
 153 void announce_SAPHandlerDestroy( sap_handler_t *p_sap )
 154 {
 155     int i;
 156
 157     vlc_mutex_destroy( &p_sap->object_lock );
 158
 159     /* Free the remaining sessions */
 160     for( i = 0 ; i< p_sap->i_sessions ; i++)
 161     {
 162         sap_session_t *p_session = p_sap->pp_sessions[i];
 163         FREENULL( p_session->psz_sdp );
 164         FREENULL( p_session->psz_data );
 165         REMOVE_ELEM( p_sap->pp_sessions, p_sap->i_sessions , i );
 166         FREENULL( p_session );
 167     }
 168
 169     /* Free the remaining addresses */
 170     for( i = 0 ; i< p_sap->i_addresses ; i++)
 171     {
 172         sap_address_t *p_address = p_sap->pp_addresses[i];
 173         FREENULL( p_address->psz_address );
 174         if( p_address->i_rfd > -1 )
 175         {
 176             net_Close( p_address->i_rfd );
 177         }
 178         if( p_address->i_wfd > -1 && p_sap->b_control )
 179         {
 180             net_Close( p_address->i_wfd );
 181         }
 182         REMOVE_ELEM( p_sap->pp_addresses, p_sap->i_addresses, i );
 183         FREENULL( p_address );
 184     }
 185
 186     /* Free the structure */
 187     vlc_object_destroy( p_sap );
 188 }
 189
 190 /**
 191  * main SAP handler thread
 192  * \param p_this the SAP Handler object
 193  * \return nothing
 194  */
 195 static void RunThread( vlc_object_t *p_this)
 196 {
 197     sap_handler_t *p_sap = (sap_handler_t*)p_this;
 198     sap_session_t *p_session;
 199
 200     while( !p_sap->b_die )
 201     {
 202         int i;
 203
 204         /* If needed, get the rate info */
 205         if( p_sap->b_control == VLC_TRUE )
 206         {
 207             for( i = 0 ; i< p_sap->i_addresses ; i++)
 208             {
 209                 if( p_sap->pp_addresses[i]->b_enabled == VLC_TRUE )
 210                 {
 211                     CalculateRate( p_sap, p_sap->pp_addresses[i] );
 212                 }
 213             }
 214         }
 215
 216         /* Find the session to announce */
 217         vlc_mutex_lock( &p_sap->object_lock );
 218         if( p_sap->i_sessions > p_sap->i_current_session + 1)
 219         {
 220             p_sap->i_current_session++;
 221         }
 222         else if( p_sap->i_sessions > 0)
 223         {
 224             p_sap->i_current_session = 0;
 225         }
 226         else
 227         {
 228             vlc_mutex_unlock( &p_sap->object_lock );
 229             msleep( SAP_IDLE );
 230             continue;
 231         }
 232         p_session = p_sap->pp_sessions[p_sap->i_current_session];
 233         vlc_mutex_unlock( &p_sap->object_lock );
 234
 235         /* And announce it */
 236         if( p_session->p_address->b_enabled == VLC_TRUE &&
 237             p_session->p_address->b_ready == VLC_TRUE )
 238         {
 239             announce_SendSAPAnnounce( p_sap, p_session );
 240         }
 241
 242         msleep( SAP_IDLE );
 243     }
 244 }
 245
 246 /* Add a SAP announce */
 247 static int announce_SAPAnnounceAdd( sap_handler_t *p_sap,
 248                              session_descriptor_t *p_session )
 249 {
 250     int i_header_size, i;
 251     char *psz_head, psz_addr[NI_MAXNUMERICHOST];
 252     vlc_bool_t b_ipv6 = VLC_FALSE, b_ssm = VLC_FALSE;
 253     sap_session_t *p_sap_session;
 254     mtime_t i_hash;
 255     struct addrinfo hints, *res;
 256     struct sockaddr_storage addr;
 257     socklen_t addrlen;
 258
 259     vlc_mutex_lock( &p_sap->object_lock );
 260
 261     if( p_session->psz_uri == NULL )
 262     {
 263         vlc_mutex_unlock( &p_sap->object_lock );
 264         msg_Err( p_sap, "*FIXME* unexpected NULL URI for SAP announce" );
 265         msg_Err( p_sap, "This should not happen. VLC needs fixing." );
 266         return VLC_EGENERIC;
 267     }
 268     /* Determine SAP multicast address automatically */
 269     memset( &hints, 0, sizeof( hints ) );
 270     hints.ai_socktype = SOCK_DGRAM;
 271     hints.ai_flags = AI_NUMERICHOST;
 272
 273     i = vlc_getaddrinfo( (vlc_object_t *)p_sap, p_session->psz_uri, 0,
 274                          &hints, &res );
 275     if( i )
 276     {
 277         vlc_mutex_unlock( &p_sap->object_lock );
 278         msg_Err( p_sap, "Invalid URI for SAP announce: %s: %s",
 279                  p_session->psz_uri, vlc_gai_strerror( i ) );
 280         return VLC_EGENERIC;
 281     }
 282
 283     addrlen = res->ai_addrlen;
 284     if ((unsigned)addrlen > sizeof (addr))
 285     {
 286         vlc_mutex_unlock( &p_sap->object_lock );
 287         vlc_freeaddrinfo( res );
 288         msg_Err( p_sap, "Unsupported address family of size %d > %u",
 289                  res->ai_addrlen, (unsigned) sizeof( addr ) );
 290         return VLC_EGENERIC;
 291     }
 292
 293     memcpy (&addr, res->ai_addr, addrlen);
 294     vlc_freeaddrinfo (res);
 295
 296     switch( addr.ss_family )
 297     {
 298 #if defined (HAVE_INET_PTON) || defined (WIN32)
 299         case AF_INET6:
 300         {
 301             /* See RFC3513 for list of valid IPv6 scopes */
 302             struct in6_addr *a6 = &((struct sockaddr_in6 *)&addr)->sin6_addr;
 303
 304             memcpy( a6->s6_addr + 2, "\x00\x00\x00\x00\x00\x00"
 305                    "\x00\x00\x00\x00\x00\x02\x7f\xfe", 14 );
 306             if( IN6_IS_ADDR_MULTICAST( a6 ) )
 307             {
 308                 /* SSM <=> ff3x::/32 */
 309                 b_ssm = (U32_AT (a6->s6_addr) & 0xfff0ffff) == 0xff300000;
 310
 311                 /* force flags to zero, preserve scope */
 312                 a6->s6_addr[1] &= 0xf;
 313             }
 314             else
 315                 /* Unicast IPv6 - assume global scope */
 316                 memcpy( a6->s6_addr, "\xff\x0e", 2 );
 317
 318             b_ipv6 = VLC_TRUE;
 319             break;
 320         }
 321 #endif
 322
 323         case AF_INET:
 324         {
 325             /* See RFC2365 for IPv4 scopes */
 326             uint32_t ipv4;
 327
 328             ipv4 = ntohl( ((struct sockaddr_in *)&addr)->sin_addr.s_addr );
 329             /* 224.0.0.0/24 => 224.0.0.255 */
 330             if ((ipv4 & 0xffffff00) == 0xe0000000)
 331                 ipv4 =  0xe00000ff;
 332             else
 333             /* 239.255.0.0/16 => 239.255.255.255 */
 334             if ((ipv4 & 0xffff0000) == 0xefff0000)
 335                 ipv4 =  0xefffffff;
 336             else
 337             /* 239.192.0.0/14 => 239.195.255.255 */
 338             if ((ipv4 & 0xfffc0000) == 0xefc00000)
 339                 ipv4 =  0xefc3ffff;
 340             else
 341             if ((ipv4 & 0xff000000) == 0xef000000)
 342                 ipv4 = 0;
 343             else
 344             /* other addresses => 224.2.127.254 */
 345             {
 346                 /* SSM: 232.0.0.0/8 */
 347                 b_ssm = (ipv4 >> 24) == 232;
 348                 ipv4 = 0xe0027ffe;
 349             }
 350
 351             if( ipv4 == 0 )
 352             {
 353                 msg_Err( p_sap, "Out-of-scope multicast address "
 354                         "not supported by SAP: %s", p_session->psz_uri );
 355                 vlc_mutex_unlock( &p_sap->object_lock );
 356                 return VLC_EGENERIC;
 357             }
 358
 359             ((struct sockaddr_in *)&addr)->sin_addr.s_addr = htonl( ipv4 );
 360             break;
 361         }
 362
 363         default:
 364             vlc_mutex_unlock( &p_sap->object_lock );
 365             msg_Err( p_sap, "Address family %d not supported by SAP",
 366                      addr.ss_family );
 367             return VLC_EGENERIC;
 368     }
 369
 370     i = vlc_getnameinfo( (struct sockaddr *)&addr, addrlen,
 371                          psz_addr, sizeof( psz_addr ), NULL, NI_NUMERICHOST );
 372
 373     if( i )
 374     {
 375         vlc_mutex_unlock( &p_sap->object_lock );
 376         msg_Err( p_sap, "%s", vlc_gai_strerror( i ) );
 377         return VLC_EGENERIC;
 378     }
 379
 380     msg_Dbg( p_sap, "using SAP address: %s", psz_addr);
 381
 382     /* XXX: Check for dupes */
 383     p_sap_session = (sap_session_t*)malloc(sizeof(sap_session_t));
 384     p_sap_session->p_sd = p_session;
 385     p_sap_session->p_address = NULL;
 386
 387     /* Add the address to the buffer */
 388     for( i = 0; i < p_sap->i_addresses; i++)
 389     {
 390         if( !strcmp( psz_addr, p_sap->pp_addresses[i]->psz_address ) )
 391         {
 392             p_sap_session->p_address = p_sap->pp_addresses[i];
 393             break;
 394         }
 395     }
 396
 397     if( p_sap_session->p_address == NULL )
 398     {
 399         sap_address_t *p_address = (sap_address_t *)
 400                                     malloc( sizeof(sap_address_t) );
 401         if( !p_address )
 402         {
 403             msg_Err( p_sap, "out of memory" );
 404             return VLC_ENOMEM;
 405         }
 406         p_address->psz_address = strdup( psz_addr );
 407         p_address->i_wfd = net_ConnectUDP( VLC_OBJECT(p_sap), psz_addr, SAP_PORT, 255 );
 408         if( p_address->i_wfd != -1 )
 409         {
 410             char *ptr;
 411
 412             net_StopRecv( p_address->i_wfd );
 413             net_GetSockAddress( p_address->i_wfd, p_address->psz_machine,
 414                                 NULL );
 415
 416             /* removes scope if present */
 417             ptr = strchr( p_address->psz_machine, '%' );
 418             if( ptr != NULL )
 419                 *ptr = '\0';
 420         }
 421
 422         if( p_sap->b_control == VLC_TRUE )
 423         {
 424             p_address->i_rfd = net_ListenUDP1( (vlc_object_t*)p_sap, psz_addr, SAP_PORT );
 425             if( p_address->i_rfd != -1 )
 426                 net_StopSend( p_address->i_rfd );
 427             p_address->i_buff = 0;
 428             p_address->b_enabled = VLC_TRUE;
 429             p_address->b_ready = VLC_FALSE;
 430             p_address->i_limit = 10000; /* 10000 bps */
 431             p_address->t1 = 0;
 432         }
 433         else
 434         {
 435             p_address->b_enabled = VLC_TRUE;
 436             p_address->b_ready = VLC_TRUE;
 437             p_address->i_interval = config_GetInt( p_sap,"sap-interval");
 438             p_address->i_rfd = -1;
 439         }
 440
 441         if( p_address->i_wfd == -1 || (p_address->i_rfd == -1
 442                                         && p_sap->b_control ) )
 443         {
 444             msg_Warn( p_sap, "disabling address" );
 445             p_address->b_enabled = VLC_FALSE;
 446         }
 447
 448         INSERT_ELEM( p_sap->pp_addresses,
 449                      p_sap->i_addresses,
 450                      p_sap->i_addresses,
 451                      p_address );
 452         p_sap_session->p_address = p_address;
 453     }
 454
 455
 456     /* Build the SAP Headers */
 457     i_header_size = ( b_ipv6 ? 16 : 4 ) + 20;
 458     psz_head = (char *) malloc( i_header_size * sizeof( char ) );
 459     if( psz_head == NULL )
 460     {
 461         msg_Err( p_sap, "out of memory" );
 462         return VLC_ENOMEM;
 463     }
 464
 465     /* SAPv1, not encrypted, not compressed */
 466     psz_head[0] = b_ipv6 ? 0x30 : 0x20;
 467     psz_head[1] = 0x00; /* No authentification length */
 468
 469     i_hash = mdate();
 470     psz_head[2] = (i_hash & 0xFF00) >> 8; /* Msg id hash */
 471     psz_head[3] = (i_hash & 0xFF);        /* Msg id hash 2 */
 472
 473 #if defined (HAVE_INET_PTON) || defined (WIN32)
 474     if( b_ipv6 )
 475     {
 476         inet_pton( AF_INET6, /* can't fail */
 477                    p_sap_session->p_address->psz_machine,
 478                    psz_head + 4 );
 479     }
 480     else
 481 #endif
 482     {
 483         inet_pton( AF_INET, /* can't fail */
 484                    p_sap_session->p_address->psz_machine,
 485                    psz_head + 4 );
 486     }
 487
 488     memcpy( psz_head + (b_ipv6 ? 20 : 8), "application/sdp", 15 );
 489
 490     /* If needed, build the SDP */
 491     if( p_session->psz_sdp == NULL )
 492     {
 493         p_session->psz_sdp = SDPGenerate( p_sap, p_session,
 494                                           p_sap_session->p_address, b_ssm );
 495         if( p_session->psz_sdp == NULL )
 496         {
 497             vlc_mutex_unlock( &p_sap->object_lock );
 498             return VLC_ENOMEM;
 499         }
 500     }
 501
 502     p_sap_session->psz_sdp = strdup( p_session->psz_sdp );
 503     p_sap_session->i_last = 0;
 504
 505     psz_head[ i_header_size-1 ] = '\0';
 506     p_sap_session->i_length = i_header_size + strlen( p_sap_session->psz_sdp);
 507
 508     p_sap_session->psz_data = (uint8_t *)malloc( sizeof(char)*
 509                                                  p_sap_session->i_length );
 510
 511     /* Build the final message */
 512     memcpy( p_sap_session->psz_data, psz_head, i_header_size );
 513     memcpy( p_sap_session->psz_data+i_header_size, p_sap_session->psz_sdp,
 514             strlen( p_sap_session->psz_sdp) );
 515
 516     free( psz_head );
 517
 518     /* Enqueue the announce */
 519     INSERT_ELEM( p_sap->pp_sessions,
 520                  p_sap->i_sessions,
 521                  p_sap->i_sessions,
 522                  p_sap_session );
 523     msg_Dbg( p_sap,"%i addresses, %i sessions",
 524                    p_sap->i_addresses,p_sap->i_sessions);
 525
 526     vlc_mutex_unlock( &p_sap->object_lock );
 527
 528     return VLC_SUCCESS;
 529 }
 530
 531 /* Remove a SAP Announce */
 532 static int announce_SAPAnnounceDel( sap_handler_t *p_sap,
 533                              session_descriptor_t *p_session )
 534 {
 535     int i;
 536     vlc_mutex_lock( &p_sap->object_lock );
 537
 538     msg_Dbg( p_sap, "removing session %p from SAP", p_session);
 539
 540     /* Dequeue the announce */
 541     for( i = 0; i< p_sap->i_sessions; i++)
 542     {
 543         if( p_session == p_sap->pp_sessions[i]->p_sd )
 544         {
 545             sap_session_t *p_mysession = p_sap->pp_sessions[i];
 546             REMOVE_ELEM( p_sap->pp_sessions,
 547                          p_sap->i_sessions,
 548                          i );
 549
 550             free( p_mysession->psz_sdp );
 551             free( p_mysession->psz_data );
 552             free( p_mysession );
 553             break;
 554         }
 555     }
 556
 557     /* XXX: Dequeue the address too if it is not used anymore
 558      * TODO: - address refcount
 559              - send a SAP deletion packet */
 560
 561     msg_Dbg( p_sap,"%i announcements remaining", p_sap->i_sessions );
 562
 563     vlc_mutex_unlock( &p_sap->object_lock );
 564
 565     return VLC_SUCCESS;
 566 }
 567
 568 static int announce_SendSAPAnnounce( sap_handler_t *p_sap,
 569                                      sap_session_t *p_session )
 570 {
 571     int i_ret;
 572
 573     /* This announce has never been sent yet */
 574     if( p_session->i_last == 0 )
 575     {
 576         p_session->i_next = mdate()+ p_session->p_address->i_interval*1000000;
 577         p_session->i_last = 1;
 578         return VLC_SUCCESS;
 579     }
 580
 581     if( p_session->i_next < mdate() )
 582     {
 583 #ifdef EXTRA_DEBUG
 584         msg_Dbg( p_sap, "sending announce");
 585 #endif
 586         i_ret = net_Write( p_sap, p_session->p_address->i_wfd, NULL,
 587                            p_session->psz_data,
 588                            p_session->i_length );
 589         if( i_ret != (int)p_session->i_length )
 590         {
 591             msg_Warn( p_sap, "SAP send failed on address %s (%i %i)",
 592                       p_session->p_address->psz_address,
 593                       i_ret, p_session->i_length );
 594         }
 595         p_session->i_last = p_session->i_next;
 596         p_session->i_next = p_session->i_last
 597                             + p_session->p_address->i_interval*1000000;
 598     }
 599     else
 600     {
 601         return VLC_SUCCESS;
 602     }
 603     return VLC_SUCCESS;
 604 }
 605
 606 static char *SDPGenerate( sap_handler_t *p_sap,
 607                           const session_descriptor_t *p_session,
 608                           const sap_address_t *p_addr, vlc_bool_t b_ssm )
 609 {
 610     int64_t i_sdp_id = mdate();
 611     int     i_sdp_version = 1 + p_sap->i_sessions + (rand()&0xfff);
 612     char *psz_group, *psz_name, psz_uribuf[NI_MAXNUMERICHOST], *psz_uri,
 613          *psz_sdp;
 614     char ipv;
 615
 616     psz_group = p_session->psz_group;
 617     psz_name = p_session->psz_name;
 618
 619     /* FIXME: really check that psz_uri is a real IP address
 620      * FIXME: make a common function to obtain a canonical IP address */
 621     ipv = ( strchr( p_session->psz_uri, ':' )  != NULL) ? '6' : '4';
 622     if( *p_session->psz_uri == '[' )
 623     {
 624         char *ptr;
 625
 626         strlcpy( psz_uribuf, p_session->psz_uri + 1, sizeof( psz_uribuf ) );
 627         ptr = strchr( psz_uribuf, '%' );
 628         if( ptr != NULL)
 629             *ptr = '\0';
 630         ptr = strchr( psz_uribuf, ']' );
 631         if( ptr != NULL)
 632             *ptr = '\0';
 633         psz_uri = psz_uribuf;
 634     }
 635     else
 636         psz_uri = p_session->psz_uri;
 637
 638     char *sfilter = NULL;
 639     if (b_ssm)
 640     {
 641         if (asprintf (&sfilter, "a=source-filter: incl IN IP%c * %s\r\n",
 642                       ipv, p_addr->psz_machine) == -1)
 643             return NULL;
 644     }
 645
 646     int res = asprintf (&psz_sdp,
 647                         "v=0\r\n"
 648                         "o=- "I64Fd" %d IN IP%c %s\r\n"
 649                         "s=%s\r\n"
 650                         "c=IN IP%c %s/255\r\n"
 651                         "t=0 0\r\n"
 652                         "a=tool:"PACKAGE_STRING"\r\n"
 653                         "a=recvonly\r\n"
 654                         "a=type:broadcast\n"
 655                         "%s"
 656                         "m=video %d %s %d\r\n"
 657                         "%s%s%s",
 658                         i_sdp_id, i_sdp_version,
 659                         ipv, p_addr->psz_machine,
 660                         psz_name, ipv, psz_uri,
 661                         (sfilter != NULL) ? sfilter : "",
 662                         p_session->i_port,
 663                         p_session->b_rtp ? "RTP/AVP" : "udp",
 664                         p_session->i_payload,
 665                         psz_group ? "a=x-plgroup:" : "",
 666                         psz_group ? psz_group : "", psz_group ? "\r\n" : "");
 667     if (sfilter != NULL)
 668         free (sfilter);
 669
 670     if (res == -1)
 671         return NULL;
 672
 673     msg_Dbg( p_sap, "Generated SDP (%i bytes):\n%s", strlen(psz_sdp),
 674              psz_sdp );
 675     return psz_sdp;
 676 }
 677
 678 static int CalculateRate( sap_handler_t *p_sap, sap_address_t *p_address )
 679 {
 680     int i_read;
 681     uint8_t buffer[SAP_MAX_BUFFER];
 682     int i_tot = 0;
 683     mtime_t i_temp;
 684     int i_rate;
 685
 686     if( p_address->t1 == 0 )
 687     {
 688         p_address->t1 = mdate();
 689         return VLC_SUCCESS;
 690     }
 691     do
 692     {
 693         /* Might be too slow if we have huge data */
 694         i_read = net_ReadNonBlock( p_sap, p_address->i_rfd, NULL, buffer,
 695                                    SAP_MAX_BUFFER, 0 );
 696         i_tot += i_read;
 697     } while( i_read > 0 );
 698
 699     i_temp = mdate();
 700
 701     /* We calculate the rate every 5 seconds */
 702     if( i_temp - p_address->t1 < 5000000 )
 703     {
 704         p_address->i_buff += i_tot;
 705         return VLC_SUCCESS;
 706     }
 707
 708     /* Bits/second */
 709     i_rate = (int)(8*1000000*((mtime_t)p_address->i_buff + (mtime_t)i_tot ) /
 710                         (i_temp - p_address->t1 ));
 711
 712     p_address->i_limit = 10000;
 713
 714     p_address->i_interval = ((1000*i_rate / p_address->i_limit) *
 715                             (MAX_INTERVAL - MIN_INTERVAL))/1000 + MIN_INTERVAL;
 716
 717     if( p_address->i_interval > MAX_INTERVAL || p_address->i_interval < 0 )
 718     {
 719         p_address->i_interval = MAX_INTERVAL;
 720     }
 721 #ifdef EXTRA_DEBUG
 722     msg_Dbg( p_sap,"%s:%i: rate=%i, interval = %i s",
 723              p_address->psz_address,SAP_PORT, i_rate, p_address->i_interval );
 724 #endif
 725
 726     p_address->b_ready = VLC_TRUE;
 727
 728     p_address->t1 = i_temp;
 729     p_address->i_buff = 0;
 730
 731     return VLC_SUCCESS;
 732 }