FreeRTOS/Common/ethernet/lwIP/core/ipv4/ip.c

   1 /* @file
   2  *
   3  * This is the IP layer implementation for incoming and outgoing IP traffic.
   4  *
   5  * @see ip_frag.c
   6  *
   7  */
   8 /*
   9  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without modification,
  13  * are permitted provided that the following conditions are met:
  14  *
  15  * 1. Redistributions of source code must retain the above copyright notice,
  16  *    this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright notice,
  18  *    this list of conditions and the following disclaimer in the documentation
  19  *    and/or other materials provided with the distribution.
  20  * 3. The name of the author may not be used to endorse or promote products
  21  *    derived from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  24  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  25  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  26  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  27  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  28  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  29  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  30  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  31  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  32  * OF SUCH DAMAGE.
  33  *
  34  * This file is part of the lwIP TCP/IP stack.
  35  *
  36  * Author: Adam Dunkels <adam@sics.se>
  37  *
  38  */
  39
  40 #include "lwip/opt.h"
  41
  42 #include "lwip/def.h"
  43 #include "lwip/mem.h"
  44 #include "lwip/ip.h"
  45 #include "lwip/ip_frag.h"
  46 #include "lwip/inet.h"
  47 #include "lwip/netif.h"
  48 #include "lwip/icmp.h"
  49 #include "lwip/raw.h"
  50 #include "lwip/udp.h"
  51 #include "lwip/tcp.h"
  52
  53 #include "lwip/stats.h"
  54
  55 #include "arch/perf.h"
  56
  57 #include "lwip/snmp.h"
  58 #if LWIP_DHCP
  59 #  include "lwip/dhcp.h"
  60 #endif /* LWIP_DHCP */
  61
  62 /**
  63  * Initializes the IP layer.
  64  */
  65
  66 void
  67 ip_init(void)
  68 {
  69 #if IP_FRAG
  70   ip_frag_init();
  71 #endif
  72 }
  73
  74 /**
  75  * Finds the appropriate network interface for a given IP address. It
  76  * searches the list of network interfaces linearly. A match is found
  77  * if the masked IP address of the network interface equals the masked
  78  * IP address given to the function.
  79  */
  80
  81 struct netif *
  82 ip_route(struct ip_addr *dest)
  83 {
  84   struct netif *netif;
  85
  86   /* iterate through netifs */
  87   for(netif = netif_list; netif != NULL; netif = netif->next) {
  88     /* network mask matches? */
  89     if (ip_addr_netcmp(dest, &(netif->ip_addr), &(netif->netmask))) {
  90       /* return netif on which to forward IP packet */
  91       return netif;
  92     }
  93   }
  94   /* no matching netif found, use default netif */
  95   return netif_default;
  96 }
  97 #if IP_FORWARD
  98
  99 /**
 100  * Forwards an IP packet. It finds an appropriate route for the
 101  * packet, decrements the TTL value of the packet, adjusts the
 102  * checksum and outputs the packet on the appropriate interface.
 103  */
 104
 105 static struct netif *
 106 ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
 107 {
 108   struct netif *netif;
 109
 110   PERF_START;
 111   /* Find network interface where to forward this IP packet to. */
 112   netif = ip_route((struct ip_addr *)&(iphdr->dest));
 113   if (netif == NULL) {
 114     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: no forwarding route for 0x%"X32_F" found\n",
 115                       iphdr->dest.addr));
 116     snmp_inc_ipoutnoroutes();
 117     return (struct netif *)NULL;
 118   }
 119   /* Do not forward packets onto the same network interface on which
 120    * they arrived. */
 121   if (netif == inp) {
 122     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not bouncing packets back on incoming interface.\n"));
 123     snmp_inc_ipoutnoroutes();
 124     return (struct netif *)NULL;
 125   }
 126
 127   /* decrement TTL */
 128   IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
 129   /* send ICMP if TTL == 0 */
 130   if (IPH_TTL(iphdr) == 0) {
 131     snmp_inc_ipinhdrerrors();
 132     /* Don't send ICMP messages in response to ICMP messages */
 133     if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
 134       icmp_time_exceeded(p, ICMP_TE_TTL);
 135     }
 136     return (struct netif *)NULL;
 137   }
 138
 139   /* Incrementally update the IP checksum. */
 140   if (IPH_CHKSUM(iphdr) >= htons(0xffff - 0x100)) {
 141     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100) + 1);
 142   } else {
 143     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100));
 144   }
 145
 146   LWIP_DEBUGF(IP_DEBUG, ("ip_forward: forwarding packet to 0x%"X32_F"\n",
 147                     iphdr->dest.addr));
 148
 149   IP_STATS_INC(ip.fw);
 150   IP_STATS_INC(ip.xmit);
 151   snmp_inc_ipforwdatagrams();
 152
 153   PERF_STOP("ip_forward");
 154   /* transmit pbuf on chosen interface */
 155   netif->output(netif, p, (struct ip_addr *)&(iphdr->dest));
 156   return netif;
 157 }
 158 #endif /* IP_FORWARD */
 159
 160 /**
 161  * This function is called by the network interface device driver when
 162  * an IP packet is received. The function does the basic checks of the
 163  * IP header such as packet size being at least larger than the header
 164  * size etc. If the packet was not destined for us, the packet is
 165  * forwarded (using ip_forward). The IP checksum is always checked.
 166  *
 167  * Finally, the packet is sent to the upper layer protocol input function.
 168  *
 169  *
 170  *
 171  */
 172
 173 err_t
 174 ip_input(struct pbuf *p, struct netif *inp) {
 175   struct ip_hdr *iphdr;
 176   struct netif *netif;
 177   u16_t iphdrlen;
 178
 179   IP_STATS_INC(ip.recv);
 180   snmp_inc_ipinreceives();
 181
 182   /* identify the IP header */
 183   iphdr = p->payload;
 184   if (IPH_V(iphdr) != 4) {
 185     LWIP_DEBUGF(IP_DEBUG | 1, ("IP packet dropped due to bad version number %"U16_F"\n", IPH_V(iphdr)));
 186     ip_debug_print(p);
 187     pbuf_free(p);
 188     IP_STATS_INC(ip.err);
 189     IP_STATS_INC(ip.drop);
 190     snmp_inc_ipinhdrerrors();
 191     return ERR_OK;
 192   }
 193   /* obtain IP header length in number of 32-bit words */
 194   iphdrlen = IPH_HL(iphdr);
 195   /* calculate IP header length in bytes */
 196   iphdrlen *= 4;
 197
 198   /* header length exceeds first pbuf length? */
 199   if (iphdrlen > p->len) {
 200     LWIP_DEBUGF(IP_DEBUG | 2, ("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet droppped.\n",
 201       iphdrlen, p->len));
 202     /* free (drop) packet pbufs */
 203     pbuf_free(p);
 204     IP_STATS_INC(ip.lenerr);
 205     IP_STATS_INC(ip.drop);
 206     snmp_inc_ipindiscards();
 207     return ERR_OK;
 208   }
 209
 210   /* verify checksum */
 211 #if CHECKSUM_CHECK_IP
 212   if (inet_chksum(iphdr, iphdrlen) != 0) {
 213
 214     LWIP_DEBUGF(IP_DEBUG | 2, ("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdrlen)));
 215     ip_debug_print(p);
 216     pbuf_free(p);
 217     IP_STATS_INC(ip.chkerr);
 218     IP_STATS_INC(ip.drop);
 219     snmp_inc_ipinhdrerrors();
 220     return ERR_OK;
 221   }
 222 #endif
 223
 224   /* Trim pbuf. This should have been done at the netif layer,
 225    * but we'll do it anyway just to be sure that its done. */
 226   pbuf_realloc(p, ntohs(IPH_LEN(iphdr)));
 227
 228   /* match packet against an interface, i.e. is this packet for us? */
 229   for (netif = netif_list; netif != NULL; netif = netif->next) {
 230
 231     LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%"X32_F" netif->ip_addr 0x%"X32_F" (0x%"X32_F", 0x%"X32_F", 0x%"X32_F")\n",
 232       iphdr->dest.addr, netif->ip_addr.addr,
 233       iphdr->dest.addr & netif->netmask.addr,
 234       netif->ip_addr.addr & netif->netmask.addr,
 235       iphdr->dest.addr & ~(netif->netmask.addr)));
 236
 237     /* interface is up and configured? */
 238     if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr))))
 239     {
 240       /* unicast to this interface address? */
 241       if (ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
 242          /* or broadcast on this interface network address? */
 243          ip_addr_isbroadcast(&(iphdr->dest), netif)) {
 244         LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
 245           netif->name[0], netif->name[1]));
 246         /* break out of for loop */
 247         break;
 248       }
 249     }
 250   }
 251 #if LWIP_DHCP
 252   /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
 253    * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
 254    * According to RFC 1542 section 3.1.1, referred by RFC 2131).
 255    */
 256   if (netif == NULL) {
 257     /* remote port is DHCP server? */
 258     if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
 259       LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: UDP packet to DHCP client port %"U16_F"\n",
 260         ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdrlen))->dest)));
 261       if (ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdrlen))->dest) == DHCP_CLIENT_PORT) {
 262         LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: DHCP packet accepted.\n"));
 263         netif = inp;
 264       }
 265     }
 266   }
 267 #endif /* LWIP_DHCP */
 268   /* packet not for us? */
 269   if (netif == NULL) {
 270     /* packet not for us, route or discard */
 271     LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: packet not for us.\n"));
 272 #if IP_FORWARD
 273     /* non-broadcast packet? */
 274     if (!ip_addr_isbroadcast(&(iphdr->dest), inp)) {
 275       /* try to forward IP packet on (other) interfaces */
 276       ip_forward(p, iphdr, inp);
 277     }
 278     else
 279 #endif /* IP_FORWARD */
 280     {
 281       snmp_inc_ipinaddrerrors();
 282       snmp_inc_ipindiscards();
 283     }
 284     pbuf_free(p);
 285     return ERR_OK;
 286   }
 287   /* packet consists of multiple fragments? */
 288   if ((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
 289 #if IP_REASSEMBLY /* packet fragment reassembly code present? */
 290     LWIP_DEBUGF(IP_DEBUG, ("IP packet is a fragment (id=0x%04"X16_F" tot_len=%"U16_F" len=%"U16_F" MF=%"U16_F" offset=%"U16_F"), calling ip_reass()\n",
 291       ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & htons(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
 292     /* reassemble the packet*/
 293     p = ip_reass(p);
 294     /* packet not fully reassembled yet? */
 295     if (p == NULL) {
 296       return ERR_OK;
 297     }
 298     iphdr = p->payload;
 299 #else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
 300     pbuf_free(p);
 301     LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
 302       ntohs(IPH_OFFSET(iphdr))));
 303     IP_STATS_INC(ip.opterr);
 304     IP_STATS_INC(ip.drop);
 305     /* unsupported protocol feature */
 306     snmp_inc_ipinunknownprotos();
 307     return ERR_OK;
 308 #endif /* IP_REASSEMBLY */
 309   }
 310
 311 #if IP_OPTIONS == 0 /* no support for IP options in the IP header? */
 312   if (iphdrlen > IP_HLEN) {
 313     LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since there were IP options (while IP_OPTIONS == 0).\n"));
 314     pbuf_free(p);
 315     IP_STATS_INC(ip.opterr);
 316     IP_STATS_INC(ip.drop);
 317     /* unsupported protocol feature */
 318     snmp_inc_ipinunknownprotos();
 319     return ERR_OK;
 320   }
 321 #endif /* IP_OPTIONS == 0 */
 322
 323   /* send to upper layers */
 324   LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n"));
 325   ip_debug_print(p);
 326   LWIP_DEBUGF(IP_DEBUG, ("ip_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));
 327
 328 #if LWIP_RAW
 329   /* raw input did not eat the packet? */
 330   if (raw_input(p, inp) == 0) {
 331 #endif /* LWIP_RAW */
 332
 333   switch (IPH_PROTO(iphdr)) {
 334 #if LWIP_UDP
 335   case IP_PROTO_UDP:
 336   case IP_PROTO_UDPLITE:
 337     snmp_inc_ipindelivers();
 338     udp_input(p, inp);
 339     break;
 340 #endif /* LWIP_UDP */
 341 #if LWIP_TCP
 342   case IP_PROTO_TCP:
 343     snmp_inc_ipindelivers();
 344     tcp_input(p, inp);
 345     break;
 346 #endif /* LWIP_TCP */
 347   case IP_PROTO_ICMP:
 348     snmp_inc_ipindelivers();
 349     icmp_input(p, inp);
 350     break;
 351   default:
 352     /* send ICMP destination protocol unreachable unless is was a broadcast */
 353     if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
 354         !ip_addr_ismulticast(&(iphdr->dest))) {
 355       p->payload = iphdr;
 356       icmp_dest_unreach(p, ICMP_DUR_PROTO);
 357     }
 358     pbuf_free(p);
 359
 360     LWIP_DEBUGF(IP_DEBUG | 2, ("Unsupported transport protocol %"U16_F"\n", IPH_PROTO(iphdr)));
 361
 362     IP_STATS_INC(ip.proterr);
 363     IP_STATS_INC(ip.drop);
 364     snmp_inc_ipinunknownprotos();
 365   }
 366 #if LWIP_RAW
 367   } /* LWIP_RAW */
 368 #endif
 369   return ERR_OK;
 370 }
 371
 372 /**
 373  * Sends an IP packet on a network interface. This function constructs
 374  * the IP header and calculates the IP header checksum. If the source
 375  * IP address is NULL, the IP address of the outgoing network
 376  * interface is filled in as source address.
 377  *
 378  * @note ip_id: RFC791 "some host may be able to simply use
 379  *  unique identifiers independent of destination"
 380  */
 381
 382 err_t
 383 ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
 384              u8_t ttl, u8_t tos,
 385              u8_t proto, struct netif *netif)
 386 {
 387   struct ip_hdr *iphdr;
 388   static u16_t ip_id = 0;
 389
 390   snmp_inc_ipoutrequests();
 391
 392   if (dest != IP_HDRINCL) {
 393     if (pbuf_header(p, IP_HLEN)) {
 394       LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output: not enough room for IP header in pbuf\n"));
 395
 396       IP_STATS_INC(ip.err);
 397       snmp_inc_ipoutdiscards();
 398       return ERR_BUF;
 399     }
 400
 401     iphdr = p->payload;
 402
 403     IPH_TTL_SET(iphdr, ttl);
 404     IPH_PROTO_SET(iphdr, proto);
 405
 406     ip_addr_set(&(iphdr->dest), dest);
 407
 408     IPH_VHLTOS_SET(iphdr, 4, IP_HLEN / 4, tos);
 409     IPH_LEN_SET(iphdr, htons(p->tot_len));
 410     IPH_OFFSET_SET(iphdr, htons(IP_DF));
 411     IPH_ID_SET(iphdr, htons(ip_id));
 412     ++ip_id;
 413
 414     if (ip_addr_isany(src)) {
 415       ip_addr_set(&(iphdr->src), &(netif->ip_addr));
 416     } else {
 417       ip_addr_set(&(iphdr->src), src);
 418     }
 419
 420     IPH_CHKSUM_SET(iphdr, 0);
 421 #if CHECKSUM_GEN_IP
 422     IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
 423 #endif
 424   } else {
 425     iphdr = p->payload;
 426     dest = &(iphdr->dest);
 427   }
 428
 429 #if IP_FRAG
 430   /* don't fragment if interface has mtu set to 0 [loopif] */
 431   if (netif->mtu && (p->tot_len > netif->mtu))
 432     return ip_frag(p,netif,dest);
 433 #endif
 434
 435   IP_STATS_INC(ip.xmit);
 436
 437   LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], netif->num));
 438   ip_debug_print(p);
 439
 440   LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
 441
 442   return netif->output(netif, p, dest);
 443 }
 444
 445 /**
 446  * Simple interface to ip_output_if. It finds the outgoing network
 447  * interface and calls upon ip_output_if to do the actual work.
 448  */
 449
 450 err_t
 451 ip_output(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
 452           u8_t ttl, u8_t tos, u8_t proto)
 453 {
 454   struct netif *netif;
 455
 456   if ((netif = ip_route(dest)) == NULL) {
 457     LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output: No route to 0x%"X32_F"\n", dest->addr));
 458
 459     IP_STATS_INC(ip.rterr);
 460     snmp_inc_ipoutnoroutes();
 461     return ERR_RTE;
 462   }
 463
 464   return ip_output_if(p, src, dest, ttl, tos, proto, netif);
 465 }
 466
 467 #if IP_DEBUG
 468 void
 469 ip_debug_print(struct pbuf *p)
 470 {
 471   struct ip_hdr *iphdr = p->payload;
 472   u8_t *payload;
 473
 474   payload = (u8_t *)iphdr + IP_HLEN;
 475
 476   LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
 477   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
 478   LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" |  0x%02"X16_F" |     %5"U16_F"     | (v, hl, tos, len)\n",
 479                     IPH_V(iphdr),
 480                     IPH_HL(iphdr),
 481                     IPH_TOS(iphdr),
 482                     ntohs(IPH_LEN(iphdr))));
 483   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
 484   LWIP_DEBUGF(IP_DEBUG, ("|    %5"U16_F"      |%"U16_F"%"U16_F"%"U16_F"|    %4"U16_F"   | (id, flags, offset)\n",
 485                     ntohs(IPH_ID(iphdr)),
 486                     ntohs(IPH_OFFSET(iphdr)) >> 15 & 1,
 487                     ntohs(IPH_OFFSET(iphdr)) >> 14 & 1,
 488                     ntohs(IPH_OFFSET(iphdr)) >> 13 & 1,
 489                     ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK));
 490   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
 491   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |    0x%04"X16_F"     | (ttl, proto, chksum)\n",
 492                     IPH_TTL(iphdr),
 493                     IPH_PROTO(iphdr),
 494                     ntohs(IPH_CHKSUM(iphdr))));
 495   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
 496   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (src)\n",
 497                     ip4_addr1(&iphdr->src),
 498                     ip4_addr2(&iphdr->src),
 499                     ip4_addr3(&iphdr->src),
 500                     ip4_addr4(&iphdr->src)));
 501   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
 502   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (dest)\n",
 503                     ip4_addr1(&iphdr->dest),
 504                     ip4_addr2(&iphdr->dest),
 505                     ip4_addr3(&iphdr->dest),
 506                     ip4_addr4(&iphdr->dest)));
 507   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
 508 }
 509 #endif /* IP_DEBUG */
 510
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