FreeRTOS/Common/ethernet/lwIP_132/src/core/ipv4/igmp.c

   1 /**
   2  * @file
   3  * IGMP - Internet Group Management Protocol
   4  *
   5  */
   6
   7 /*
   8  * Copyright (c) 2002 CITEL Technologies Ltd.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of CITEL Technologies Ltd nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY CITEL TECHNOLOGIES AND CONTRIBUTORS ``AS IS''
  24  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL CITEL TECHNOLOGIES OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  * This file is a contribution to the lwIP TCP/IP stack.
  36  * The Swedish Institute of Computer Science and Adam Dunkels
  37  * are specifically granted permission to redistribute this
  38  * source code.
  39 */
  40
  41 /*-------------------------------------------------------------
  42 Note 1)
  43 Although the rfc requires V1 AND V2 capability
  44 we will only support v2 since now V1 is very old (August 1989)
  45 V1 can be added if required
  46
  47 a debug print and statistic have been implemented to
  48 show this up.
  49 -------------------------------------------------------------
  50 -------------------------------------------------------------
  51 Note 2)
  52 A query for a specific group address (as opposed to ALLHOSTS)
  53 has now been implemented as I am unsure if it is required
  54
  55 a debug print and statistic have been implemented to
  56 show this up.
  57 -------------------------------------------------------------
  58 -------------------------------------------------------------
  59 Note 3)
  60 The router alert rfc 2113 is implemented in outgoing packets
  61 but not checked rigorously incoming
  62 -------------------------------------------------------------
  63 Steve Reynolds
  64 ------------------------------------------------------------*/
  65
  66 /*-----------------------------------------------------------------------------
  67  * RFC 988  - Host extensions for IP multicasting                         - V0
  68  * RFC 1054 - Host extensions for IP multicasting                         -
  69  * RFC 1112 - Host extensions for IP multicasting                         - V1
  70  * RFC 2236 - Internet Group Management Protocol, Version 2               - V2  <- this code is based on this RFC (it's the "de facto" standard)
  71  * RFC 3376 - Internet Group Management Protocol, Version 3               - V3
  72  * RFC 4604 - Using Internet Group Management Protocol Version 3...       - V3+
  73  * RFC 2113 - IP Router Alert Option                                      -
  74  *----------------------------------------------------------------------------*/
  75
  76 /*-----------------------------------------------------------------------------
  77  * Includes
  78  *----------------------------------------------------------------------------*/
  79
  80 #include "lwip/opt.h"
  81
  82 #if LWIP_IGMP /* don't build if not configured for use in lwipopts.h */
  83
  84 #include "lwip/igmp.h"
  85 #include "lwip/debug.h"
  86 #include "lwip/def.h"
  87 #include "lwip/mem.h"
  88 #include "lwip/ip.h"
  89 #include "lwip/inet.h"
  90 #include "lwip/inet_chksum.h"
  91 #include "lwip/netif.h"
  92 #include "lwip/icmp.h"
  93 #include "lwip/udp.h"
  94 #include "lwip/tcp.h"
  95 #include "lwip/stats.h"
  96
  97 #include "string.h"
  98
  99 /*-----------------------------------------------------------------------------
 100  * Globales
 101  *----------------------------------------------------------------------------*/
 102
 103 static struct igmp_group* igmp_group_list;
 104 static struct ip_addr     allsystems;
 105 static struct ip_addr     allrouters;
 106
 107 /**
 108  * Initialize the IGMP module
 109  */
 110 void
 111 igmp_init(void)
 112 {
 113   LWIP_DEBUGF(IGMP_DEBUG, ("igmp_init: initializing\n"));
 114
 115   IP4_ADDR(&allsystems, 224, 0, 0, 1);
 116   IP4_ADDR(&allrouters, 224, 0, 0, 2);
 117 }
 118
 119 #ifdef LWIP_DEBUG
 120 /**
 121  * Dump global IGMP groups list
 122  */
 123 void
 124 igmp_dump_group_list()
 125 {
 126   struct igmp_group *group = igmp_group_list;
 127
 128   while (group != NULL) {
 129     LWIP_DEBUGF(IGMP_DEBUG, ("igmp_dump_group_list: [%"U32_F"] ", (u32_t)(group->group_state)));
 130     ip_addr_debug_print(IGMP_DEBUG, &group->group_address);
 131     LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", group->interface));
 132     group = group->next;
 133   }
 134   LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
 135 }
 136 #else
 137 #define igmp_dump_group_list()
 138 #endif /* LWIP_DEBUG */
 139
 140 /**
 141  * Start IGMP processing on interface
 142  *
 143  * @param netif network interface on which start IGMP processing
 144  */
 145 err_t
 146 igmp_start(struct netif *netif)
 147 {
 148   struct igmp_group* group;
 149
 150   LWIP_DEBUGF(IGMP_DEBUG, ("igmp_start: starting IGMP processing on if %p\n", netif));
 151
 152   group = igmp_lookup_group(netif, &allsystems);
 153
 154   if (group != NULL) {
 155     group->group_state = IGMP_GROUP_IDLE_MEMBER;
 156     group->use++;
 157
 158     /* Allow the igmp messages at the MAC level */
 159     if (netif->igmp_mac_filter != NULL) {
 160       LWIP_DEBUGF(IGMP_DEBUG, ("igmp_start: igmp_mac_filter(ADD "));
 161       ip_addr_debug_print(IGMP_DEBUG, &allsystems);
 162       LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
 163       netif->igmp_mac_filter( netif, &allsystems, IGMP_ADD_MAC_FILTER);
 164     }
 165
 166     return ERR_OK;
 167   }
 168
 169   return ERR_MEM;
 170 }
 171
 172 /**
 173  * Stop IGMP processing on interface
 174  *
 175  * @param netif network interface on which stop IGMP processing
 176  */
 177 err_t
 178 igmp_stop(struct netif *netif)
 179 {
 180   struct igmp_group *group = igmp_group_list;
 181   struct igmp_group *prev  = NULL;
 182   struct igmp_group *next;
 183
 184   /* look for groups joined on this interface further down the list */
 185   while (group != NULL) {
 186     next = group->next;
 187     /* is it a group joined on this interface? */
 188     if (group->interface == netif) {
 189       /* is it the first group of the list? */
 190       if (group == igmp_group_list) {
 191         igmp_group_list = next;
 192       }
 193       /* is there a "previous" group defined? */
 194       if (prev != NULL) {
 195         prev->next = next;
 196       }
 197       /* disable the group at the MAC level */
 198       if (netif->igmp_mac_filter != NULL) {
 199         LWIP_DEBUGF(IGMP_DEBUG, ("igmp_stop: igmp_mac_filter(DEL "));
 200         ip_addr_debug_print(IGMP_DEBUG, &group->group_address);
 201         LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
 202         netif->igmp_mac_filter(netif, &(group->group_address), IGMP_DEL_MAC_FILTER);
 203       }
 204       /* free group */
 205       memp_free(MEMP_IGMP_GROUP, group);
 206     } else {
 207       /* change the "previous" */
 208       prev = group;
 209     }
 210     /* move to "next" */
 211     group = next;
 212   }
 213   return ERR_OK;
 214 }
 215
 216 /**
 217  * Report IGMP memberships for this interface
 218  *
 219  * @param netif network interface on which report IGMP memberships
 220  */
 221 void
 222 igmp_report_groups( struct netif *netif)
 223 {
 224   struct igmp_group *group = igmp_group_list;
 225
 226   LWIP_DEBUGF(IGMP_DEBUG, ("igmp_report_groups: sending IGMP reports on if %p\n", netif));
 227
 228   while (group != NULL) {
 229     if (group->interface == netif) {
 230       igmp_delaying_member( group, IGMP_JOIN_DELAYING_MEMBER_TMR);
 231     }
 232     group = group->next;
 233   }
 234 }
 235
 236 /**
 237  * Search for a group in the global igmp_group_list
 238  *
 239  * @param ifp the network interface for which to look
 240  * @param addr the group ip address to search for
 241  * @return a struct igmp_group* if the group has been found,
 242  *         NULL if the group wasn't found.
 243  */
 244 struct igmp_group *
 245 igmp_lookfor_group(struct netif *ifp, struct ip_addr *addr)
 246 {
 247   struct igmp_group *group = igmp_group_list;
 248
 249   while (group != NULL) {
 250     if ((group->interface == ifp) && (ip_addr_cmp(&(group->group_address), addr))) {
 251       return group;
 252     }
 253     group = group->next;
 254   }
 255
 256   /* to be clearer, we return NULL here instead of
 257    * 'group' (which is also NULL at this point).
 258    */
 259   return NULL;
 260 }
 261
 262 /**
 263  * Search for a specific igmp group and create a new one if not found-
 264  *
 265  * @param ifp the network interface for which to look
 266  * @param addr the group ip address to search
 267  * @return a struct igmp_group*,
 268  *         NULL on memory error.
 269  */
 270 struct igmp_group *
 271 igmp_lookup_group(struct netif *ifp, struct ip_addr *addr)
 272 {
 273   struct igmp_group *group = igmp_group_list;
 274
 275   /* Search if the group already exists */
 276   group = igmp_lookfor_group(ifp, addr);
 277   if (group != NULL) {
 278     /* Group already exists. */
 279     return group;
 280   }
 281
 282   /* Group doesn't exist yet, create a new one */
 283   group = memp_malloc(MEMP_IGMP_GROUP);
 284   if (group != NULL) {
 285     group->interface          = ifp;
 286     ip_addr_set(&(group->group_address), addr);
 287     group->timer              = 0; /* Not running */
 288     group->group_state        = IGMP_GROUP_NON_MEMBER;
 289     group->last_reporter_flag = 0;
 290     group->use                = 0;
 291     group->next               = igmp_group_list;
 292
 293     igmp_group_list = group;
 294   }
 295
 296   LWIP_DEBUGF(IGMP_DEBUG, ("igmp_lookup_group: %sallocated a new group with address ", (group?"":"impossible to ")));
 297   ip_addr_debug_print(IGMP_DEBUG, addr);
 298   LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", ifp));
 299
 300   return group;
 301 }
 302
 303 /**
 304  * Remove a group in the global igmp_group_list
 305  *
 306  * @param group the group to remove from the global igmp_group_list
 307  * @return ERR_OK if group was removed from the list, an err_t otherwise
 308  */
 309 err_t
 310 igmp_remove_group(struct igmp_group *group)
 311 {
 312   err_t err = ERR_OK;
 313
 314   /* Is it the first group? */
 315   if (igmp_group_list == group) {
 316     igmp_group_list = group->next;
 317   } else {
 318     /* look for group further down the list */
 319     struct igmp_group *tmpGroup;
 320     for (tmpGroup = igmp_group_list; tmpGroup != NULL; tmpGroup = tmpGroup->next) {
 321       if (tmpGroup->next == group) {
 322         tmpGroup->next = group->next;
 323         break;
 324       }
 325     }
 326     /* Group not found in the global igmp_group_list */
 327     if (tmpGroup == NULL)
 328       err = ERR_ARG;
 329   }
 330   /* free group */
 331   memp_free(MEMP_IGMP_GROUP, group);
 332
 333   return err;
 334 }
 335
 336 /**
 337  * Called from ip_input() if a new IGMP packet is received.
 338  *
 339  * @param p received igmp packet, p->payload pointing to the ip header
 340  * @param inp network interface on which the packet was received
 341  * @param dest destination ip address of the igmp packet
 342  */
 343 void
 344 igmp_input(struct pbuf *p, struct netif *inp, struct ip_addr *dest)
 345 {
 346   struct ip_hdr *    iphdr;
 347   struct igmp_msg*   igmp;
 348   struct igmp_group* group;
 349   struct igmp_group* groupref;
 350
 351   /* Note that the length CAN be greater than 8 but only 8 are used - All are included in the checksum */
 352   iphdr = p->payload;
 353   if (pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4)) || (p->len < IGMP_MINLEN)) {
 354     pbuf_free(p);
 355     IGMP_STATS_INC(igmp.lenerr);
 356     LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: length error\n"));
 357     return;
 358   }
 359
 360   LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: message from "));
 361   ip_addr_debug_print(IGMP_DEBUG, &(iphdr->src));
 362   LWIP_DEBUGF(IGMP_DEBUG, (" to address "));
 363   ip_addr_debug_print(IGMP_DEBUG, &(iphdr->dest));
 364   LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", inp));
 365
 366   /* Now calculate and check the checksum */
 367   igmp = (struct igmp_msg *)p->payload;
 368   if (inet_chksum(igmp, p->len)) {
 369     pbuf_free(p);
 370     IGMP_STATS_INC(igmp.chkerr);
 371     LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: checksum error\n"));
 372     return;
 373   }
 374
 375   /* Packet is ok so find an existing group */
 376   group = igmp_lookfor_group(inp, dest); /* use the incoming IP address! */
 377
 378   /* If group can be found or create... */
 379   if (!group) {
 380     pbuf_free(p);
 381     LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP frame not for us\n"));
 382     return;
 383   }
 384
 385   /* NOW ACT ON THE INCOMING MESSAGE TYPE... */
 386   switch (igmp->igmp_msgtype) {
 387    case IGMP_MEMB_QUERY: {
 388      /* IGMP_MEMB_QUERY to the "all systems" address ? */
 389      if ((ip_addr_cmp(dest, &allsystems)) && (igmp->igmp_group_address.addr == 0)) {
 390        /* THIS IS THE GENERAL QUERY */
 391        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: General IGMP_MEMB_QUERY on \"ALL SYSTEMS\" address (224.0.0.1) [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));
 392
 393        if (igmp->igmp_maxresp == 0) {
 394          IGMP_STATS_INC(igmp.v1_rxed);
 395          LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: got an all hosts query with time== 0 - this is V1 and not implemented - treat as v2\n"));
 396          igmp->igmp_maxresp = IGMP_V1_DELAYING_MEMBER_TMR;
 397        }
 398
 399        IGMP_STATS_INC(igmp.group_query_rxed);
 400        groupref = igmp_group_list;
 401        while (groupref) {
 402          /* Do not send messages on the all systems group address! */
 403          if ((groupref->interface == inp) && (!(ip_addr_cmp(&(groupref->group_address), &allsystems)))) {
 404            igmp_delaying_member( groupref, igmp->igmp_maxresp);
 405          }
 406          groupref = groupref->next;
 407        }
 408      } else {
 409        /* IGMP_MEMB_QUERY to a specific group ? */
 410        if (group->group_address.addr != 0) {
 411          LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP_MEMB_QUERY to a specific group "));
 412          ip_addr_debug_print(IGMP_DEBUG, &group->group_address);
 413          if (ip_addr_cmp (dest, &allsystems)) {
 414            LWIP_DEBUGF(IGMP_DEBUG, (" using \"ALL SYSTEMS\" address (224.0.0.1) [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));
 415            /* we first need to re-lookfor the group since we used dest last time */
 416            group = igmp_lookfor_group(inp, &igmp->igmp_group_address);
 417          } else {
 418            LWIP_DEBUGF(IGMP_DEBUG, (" with the group address as destination [igmp_maxresp=%i]\n", (int)(igmp->igmp_maxresp)));
 419          }
 420
 421          if (group != NULL) {
 422            IGMP_STATS_INC(igmp.unicast_query);
 423            igmp_delaying_member( group, igmp->igmp_maxresp);
 424          }
 425        }
 426      }
 427      break;
 428    }
 429    case IGMP_V2_MEMB_REPORT: {
 430      LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: IGMP_V2_MEMB_REPORT\n"));
 431
 432      IGMP_STATS_INC(igmp.report_rxed);
 433      if (group->group_state == IGMP_GROUP_DELAYING_MEMBER) {
 434        /* This is on a specific group we have already looked up */
 435        group->timer = 0; /* stopped */
 436        group->group_state = IGMP_GROUP_IDLE_MEMBER;
 437        group->last_reporter_flag = 0;
 438      }
 439      break;
 440    }
 441    default: {
 442      LWIP_DEBUGF(IGMP_DEBUG, ("igmp_input: unexpected msg %d in state %d on group %p on if %p\n",
 443        igmp->igmp_msgtype, group->group_state, &group, group->interface));
 444      break;
 445    }
 446   }
 447
 448   pbuf_free(p);
 449   return;
 450 }
 451
 452 /**
 453  * Join a group on one network interface.
 454  *
 455  * @param ifaddr ip address of the network interface which should join a new group
 456  * @param groupaddr the ip address of the group which to join
 457  * @return ERR_OK if group was joined on the netif(s), an err_t otherwise
 458  */
 459 err_t
 460 igmp_joingroup(struct ip_addr *ifaddr, struct ip_addr *groupaddr)
 461 {
 462   err_t              err = ERR_VAL; /* no matching interface */
 463   struct igmp_group *group;
 464   struct netif      *netif;
 465
 466   /* make sure it is multicast address */
 467   LWIP_ERROR("igmp_joingroup: attempt to join non-multicast address", ip_addr_ismulticast(groupaddr), return ERR_VAL;);
 468   LWIP_ERROR("igmp_joingroup: attempt to join allsystems address", (!ip_addr_cmp(groupaddr, &allsystems)), return ERR_VAL;);
 469
 470   /* loop through netif's */
 471   netif = netif_list;
 472   while (netif != NULL) {
 473     /* Should we join this interface ? */
 474     if ((netif->flags & NETIF_FLAG_IGMP) && ((ip_addr_isany(ifaddr) || ip_addr_cmp(&(netif->ip_addr), ifaddr)))) {
 475       /* find group or create a new one if not found */
 476       group = igmp_lookup_group(netif, groupaddr);
 477
 478       if (group != NULL) {
 479         /* This should create a new group, check the state to make sure */
 480         if (group->group_state != IGMP_GROUP_NON_MEMBER) {
 481           LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: join to group not in state IGMP_GROUP_NON_MEMBER\n"));
 482         } else {
 483           /* OK - it was new group */
 484           LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: join to new group: "));
 485           ip_addr_debug_print(IGMP_DEBUG, groupaddr);
 486           LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
 487
 488           /* If first use of the group, allow the group at the MAC level */
 489           if ((group->use==0) && (netif->igmp_mac_filter != NULL)) {
 490             LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: igmp_mac_filter(ADD "));
 491             ip_addr_debug_print(IGMP_DEBUG, groupaddr);
 492             LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
 493             netif->igmp_mac_filter(netif, groupaddr, IGMP_ADD_MAC_FILTER);
 494           }
 495
 496           IGMP_STATS_INC(igmp.join_sent);
 497           igmp_send(group, IGMP_V2_MEMB_REPORT);
 498
 499           igmp_start_timer(group, IGMP_JOIN_DELAYING_MEMBER_TMR);
 500
 501           /* Need to work out where this timer comes from */
 502           group->group_state = IGMP_GROUP_DELAYING_MEMBER;
 503         }
 504         /* Increment group use */
 505         group->use++;
 506         /* Join on this interface */
 507         err = ERR_OK;
 508       } else {
 509         /* Return an error even if some network interfaces are joined */
 510         /** @todo undo any other netif already joined */
 511         LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: Not enought memory to join to group\n"));
 512         return ERR_MEM;
 513       }
 514     }
 515     /* proceed to next network interface */
 516     netif = netif->next;
 517   }
 518
 519   return err;
 520 }
 521
 522 /**
 523  * Leave a group on one network interface.
 524  *
 525  * @param ifaddr ip address of the network interface which should leave a group
 526  * @param groupaddr the ip address of the group which to leave
 527  * @return ERR_OK if group was left on the netif(s), an err_t otherwise
 528  */
 529 err_t
 530 igmp_leavegroup(struct ip_addr *ifaddr, struct ip_addr *groupaddr)
 531 {
 532   err_t              err = ERR_VAL; /* no matching interface */
 533   struct igmp_group *group;
 534   struct netif      *netif;
 535
 536   /* make sure it is multicast address */
 537   LWIP_ERROR("igmp_leavegroup: attempt to leave non-multicast address", ip_addr_ismulticast(groupaddr), return ERR_VAL;);
 538   LWIP_ERROR("igmp_leavegroup: attempt to leave allsystems address", (!ip_addr_cmp(groupaddr, &allsystems)), return ERR_VAL;);
 539
 540   /* loop through netif's */
 541   netif = netif_list;
 542   while (netif != NULL) {
 543     /* Should we leave this interface ? */
 544     if ((netif->flags & NETIF_FLAG_IGMP) && ((ip_addr_isany(ifaddr) || ip_addr_cmp(&(netif->ip_addr), ifaddr)))) {
 545       /* find group */
 546       group = igmp_lookfor_group(netif, groupaddr);
 547
 548       if (group != NULL) {
 549         /* Only send a leave if the flag is set according to the state diagram */
 550         LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: Leaving group: "));
 551         ip_addr_debug_print(IGMP_DEBUG, groupaddr);
 552         LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
 553
 554         /* If there is no other use of the group */
 555         if (group->use <= 1) {
 556           /* If we are the last reporter for this group */
 557           if (group->last_reporter_flag) {
 558             LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: sending leaving group\n"));
 559             IGMP_STATS_INC(igmp.leave_sent);
 560             igmp_send(group, IGMP_LEAVE_GROUP);
 561           }
 562
 563           /* Disable the group at the MAC level */
 564           if (netif->igmp_mac_filter != NULL) {
 565             LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: igmp_mac_filter(DEL "));
 566             ip_addr_debug_print(IGMP_DEBUG, groupaddr);
 567             LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", netif));
 568             netif->igmp_mac_filter(netif, groupaddr, IGMP_DEL_MAC_FILTER);
 569           }
 570
 571           LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: remove group: "));
 572           ip_addr_debug_print(IGMP_DEBUG, groupaddr);
 573           LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
 574
 575           /* Free the group */
 576           igmp_remove_group(group);
 577         } else {
 578           /* Decrement group use */
 579           group->use--;
 580         }
 581         /* Leave on this interface */
 582         err = ERR_OK;
 583       } else {
 584         /* It's not a fatal error on "leavegroup" */
 585         LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: not member of group\n"));
 586       }
 587     }
 588     /* proceed to next network interface */
 589     netif = netif->next;
 590   }
 591
 592   return err;
 593 }
 594
 595 /**
 596  * The igmp timer function (both for NO_SYS=1 and =0)
 597  * Should be called every IGMP_TMR_INTERVAL milliseconds (100 ms is default).
 598  */
 599 void
 600 igmp_tmr(void)
 601 {
 602   struct igmp_group *group = igmp_group_list;
 603
 604   while (group != NULL) {
 605     if (group->timer != 0) {
 606       group->timer -= 1;
 607       if (group->timer == 0) {
 608         igmp_timeout(group);
 609       }
 610     }
 611     group = group->next;
 612   }
 613 }
 614
 615 /**
 616  * Called if a timeout for one group is reached.
 617  * Sends a report for this group.
 618  *
 619  * @param group an igmp_group for which a timeout is reached
 620  */
 621 void
 622 igmp_timeout(struct igmp_group *group)
 623 {
 624   /* If the state is IGMP_GROUP_DELAYING_MEMBER then we send a report for this group */
 625   if (group->group_state == IGMP_GROUP_DELAYING_MEMBER) {
 626     LWIP_DEBUGF(IGMP_DEBUG, ("igmp_timeout: report membership for group with address "));
 627     ip_addr_debug_print(IGMP_DEBUG, &(group->group_address));
 628     LWIP_DEBUGF(IGMP_DEBUG, (" on if %p\n", group->interface));
 629
 630     igmp_send(group, IGMP_V2_MEMB_REPORT);
 631   }
 632 }
 633
 634 /**
 635  * Start a timer for an igmp group
 636  *
 637  * @param group the igmp_group for which to start a timer
 638  * @param max_time the time in multiples of IGMP_TMR_INTERVAL (decrease with
 639  *        every call to igmp_tmr())
 640  */
 641 void
 642 igmp_start_timer(struct igmp_group *group, u8_t max_time)
 643 {
 644   /**
 645    * @todo Important !! this should be random 0 -> max_time. Find out how to do this
 646    */
 647   group->timer = max_time;
 648 }
 649
 650 /**
 651  * Stop a timer for an igmp_group
 652  *
 653  * @param group the igmp_group for which to stop the timer
 654  */
 655 void
 656 igmp_stop_timer(struct igmp_group *group)
 657 {
 658   group->timer = 0;
 659 }
 660
 661 /**
 662  * Delaying membership report for a group if necessary
 663  *
 664  * @param group the igmp_group for which "delaying" membership report
 665  * @param maxresp query delay
 666  */
 667 void
 668 igmp_delaying_member( struct igmp_group *group, u8_t maxresp)
 669 {
 670   if ((group->group_state == IGMP_GROUP_IDLE_MEMBER) ||
 671      ((group->group_state == IGMP_GROUP_DELAYING_MEMBER) && (maxresp > group->timer))) {
 672     igmp_start_timer(group, (maxresp)/2);
 673     group->group_state = IGMP_GROUP_DELAYING_MEMBER;
 674   }
 675 }
 676
 677
 678 /**
 679  * Sends an IP packet on a network interface. This function constructs the IP header
 680  * and calculates the IP header checksum. If the source IP address is NULL,
 681  * the IP address of the outgoing network interface is filled in as source address.
 682  *
 683  * @param p the packet to send (p->payload points to the data, e.g. next
 684             protocol header; if dest == IP_HDRINCL, p already includes an IP
 685             header and p->payload points to that IP header)
 686  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
 687  *         IP  address of the netif used to send is used as source address)
 688  * @param dest the destination IP address to send the packet to
 689  * @param ttl the TTL value to be set in the IP header
 690  * @param proto the PROTOCOL to be set in the IP header
 691  * @param netif the netif on which to send this packet
 692  * @return ERR_OK if the packet was sent OK
 693  *         ERR_BUF if p doesn't have enough space for IP/LINK headers
 694  *         returns errors returned by netif->output
 695  */
 696 err_t
 697 igmp_ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
 698                   u8_t ttl, u8_t proto, struct netif *netif)
 699 {
 700   /* This is the "router alert" option */
 701   u16_t ra[2];
 702   ra[0] = htons (ROUTER_ALERT);
 703   ra[1] = 0x0000; /* Router shall examine packet */
 704   return ip_output_if_opt(p, src, dest, ttl, 0, proto, netif, ra, ROUTER_ALERTLEN);
 705 }
 706
 707 /**
 708  * Send an igmp packet to a specific group.
 709  *
 710  * @param group the group to which to send the packet
 711  * @param type the type of igmp packet to send
 712  */
 713 void
 714 igmp_send(struct igmp_group *group, u8_t type)
 715 {
 716   struct pbuf*     p    = NULL;
 717   struct igmp_msg* igmp = NULL;
 718   struct ip_addr   src  = {0};
 719   struct ip_addr*  dest = NULL;
 720
 721   /* IP header + "router alert" option + IGMP header */
 722   p = pbuf_alloc(PBUF_TRANSPORT, IGMP_MINLEN, PBUF_RAM);
 723
 724   if (p) {
 725     igmp = p->payload;
 726     LWIP_ASSERT("igmp_send: check that first pbuf can hold struct igmp_msg",
 727                (p->len >= sizeof(struct igmp_msg)));
 728     ip_addr_set(&src, &((group->interface)->ip_addr));
 729
 730     if (type == IGMP_V2_MEMB_REPORT) {
 731       dest = &(group->group_address);
 732       IGMP_STATS_INC(igmp.report_sent);
 733       ip_addr_set(&(igmp->igmp_group_address), &(group->group_address));
 734       group->last_reporter_flag = 1; /* Remember we were the last to report */
 735     } else {
 736       if (type == IGMP_LEAVE_GROUP) {
 737         dest = &allrouters;
 738         ip_addr_set(&(igmp->igmp_group_address), &(group->group_address));
 739       }
 740     }
 741
 742     if ((type == IGMP_V2_MEMB_REPORT) || (type == IGMP_LEAVE_GROUP)) {
 743       igmp->igmp_msgtype  = type;
 744       igmp->igmp_maxresp  = 0;
 745       igmp->igmp_checksum = 0;
 746       igmp->igmp_checksum = inet_chksum( igmp, IGMP_MINLEN);
 747
 748       igmp_ip_output_if(p, &src, dest, IGMP_TTL, IP_PROTO_IGMP, group->interface);
 749     }
 750
 751     pbuf_free(p);
 752   } else {
 753     LWIP_DEBUGF(IGMP_DEBUG, ("igmp_send: not enough memory for igmp_send\n"));
 754   }
 755 }
 756
 757 #endif /* LWIP_IGMP */