Projects/Incomplete/Webserver/Lib/uip/uip-fw.c

   1 /*
   2  * Copyright (c) 2004, Swedish Institute of Computer Science.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the Institute nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * This file is part of the uIP TCP/IP stack
  30  *
  31  * Author: Adam Dunkels <adam@sics.se>
  32  *
  33  * $Id: uip-fw.c,v 1.2 2006/06/12 08:00:30 adam Exp $
  34  */
  35 /**
  36  * \addtogroup uip
  37  * @{
  38  */
  39
  40 /**
  41  * \defgroup uipfw uIP packet forwarding
  42  * @{
  43  *
  44  */
  45
  46 /**
  47  * \file
  48  * uIP packet forwarding.
  49  * \author Adam Dunkels <adam@sics.se>
  50  *
  51  * This file implements a number of simple functions which do packet
  52  * forwarding over multiple network interfaces with uIP.
  53  *
  54  */
  55
  56 #include "uip.h"
  57 #include "uip_arch.h"
  58 #include "uip-fw.h"
  59
  60 #include <string.h> /* for memcpy() */
  61
  62 /*
  63  * The list of registered network interfaces.
  64  */
  65 static struct uip_fw_netif *netifs = NULL;
  66
  67 /*
  68  * A pointer to the default network interface.
  69  */
  70 static struct uip_fw_netif *defaultnetif = NULL;
  71
  72 struct tcpip_hdr {
  73   /* IP header. */
  74   u8_t vhl,
  75     tos;
  76   u16_t len,
  77     ipid,
  78     ipoffset;
  79   u8_t ttl,
  80     proto;
  81   u16_t ipchksum;
  82   u16_t srcipaddr[2],
  83     destipaddr[2];
  84
  85   /* TCP header. */
  86   u16_t srcport,
  87     destport;
  88   u8_t seqno[4],
  89     ackno[4],
  90     tcpoffset,
  91     flags,
  92     wnd[2];
  93   u16_t tcpchksum;
  94   u8_t urgp[2];
  95   u8_t optdata[4];
  96 };
  97
  98 struct icmpip_hdr {
  99   /* IP header. */
 100   u8_t vhl,
 101     tos,
 102     len[2],
 103     ipid[2],
 104     ipoffset[2],
 105     ttl,
 106     proto;
 107   u16_t ipchksum;
 108   u16_t srcipaddr[2],
 109     destipaddr[2];
 110   /* ICMP (echo) header. */
 111   u8_t type, icode;
 112   u16_t icmpchksum;
 113   u16_t id, seqno;
 114   u8_t payload[1];
 115 };
 116
 117 /* ICMP ECHO. */
 118 #define ICMP_ECHO 8
 119
 120 /* ICMP TIME-EXCEEDED. */
 121 #define ICMP_TE 11
 122
 123 /*
 124  * Pointer to the TCP/IP headers of the packet in the uip_buf buffer.
 125  */
 126 #define BUF ((struct tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
 127
 128 /*
 129  * Pointer to the ICMP/IP headers of the packet in the uip_buf buffer.
 130  */
 131 #define ICMPBUF ((struct icmpip_hdr *)&uip_buf[UIP_LLH_LEN])
 132
 133 /*
 134  * Certain fields of an IP packet that are used for identifying
 135  * duplicate packets.
 136  */
 137 struct fwcache_entry {
 138   u16_t timer;
 139
 140   u16_t srcipaddr[2];
 141   u16_t destipaddr[2];
 142   u16_t ipid;
 143   u8_t proto;
 144   u8_t unused;
 145
 146 #if notdef
 147   u16_t payload[2];
 148 #endif
 149
 150 #if UIP_REASSEMBLY > 0
 151   u16_t len, offset;
 152 #endif
 153 };
 154
 155 /*
 156  * The number of packets to remember when looking for duplicates.
 157  */
 158 #ifdef UIP_CONF_FWCACHE_SIZE
 159 #define FWCACHE_SIZE UIP_CONF_FWCACHE_SIZE
 160 #else
 161 #define FWCACHE_SIZE 2
 162 #endif
 163
 164
 165 /*
 166  * A cache of packet header fields which are used for
 167  * identifying duplicate packets.
 168  */
 169 static struct fwcache_entry fwcache[FWCACHE_SIZE];
 170
 171 /**
 172  * \internal
 173  * The time that a packet cache is active.
 174  */
 175 #define FW_TIME 20
 176
 177 /*------------------------------------------------------------------------------*/
 178 /**
 179  * Initialize the uIP packet forwarding module.
 180  */
 181 /*------------------------------------------------------------------------------*/
 182 void
 183 uip_fw_init(void)
 184 {
 185   struct uip_fw_netif *t;
 186   defaultnetif = NULL;
 187   while(netifs != NULL) {
 188     t = netifs;
 189     netifs = netifs->next;
 190     t->next = NULL;
 191   }
 192 }
 193 /*------------------------------------------------------------------------------*/
 194 /**
 195  * \internal
 196  * Check if an IP address is within the network defined by an IP
 197  * address and a netmask.
 198  *
 199  * \param ipaddr The IP address to be checked.
 200  * \param netipaddr The IP address of the network.
 201  * \param netmask The netmask of the network.
 202  *
 203  * \return Non-zero if IP address is in network, zero otherwise.
 204  */
 205 /*------------------------------------------------------------------------------*/
 206 static unsigned char
 207 ipaddr_maskcmp(u16_t *ipaddr, u16_t *netipaddr, u16_t *netmask)
 208 {
 209   return (ipaddr[0] & netmask [0]) == (netipaddr[0] & netmask[0]) &&
 210     (ipaddr[1] & netmask[1]) == (netipaddr[1] & netmask[1]);
 211 }
 212 /*------------------------------------------------------------------------------*/
 213 /**
 214  * \internal
 215  * Send out an ICMP TIME-EXCEEDED message.
 216  *
 217  * This function replaces the packet in the uip_buf buffer with the
 218  * ICMP packet.
 219  */
 220 /*------------------------------------------------------------------------------*/
 221 static void
 222 time_exceeded(void)
 223 {
 224   u16_t tmp16;
 225
 226   /* We don't send out ICMP errors for ICMP messages. */
 227   if(ICMPBUF->proto == UIP_PROTO_ICMP) {
 228     uip_len = 0;
 229     return;
 230   }
 231   /* Copy fields from packet header into payload of this ICMP packet. */
 232   memcpy(&(ICMPBUF->payload[0]), ICMPBUF, 28);
 233
 234   /* Set the ICMP type and code. */
 235   ICMPBUF->type = ICMP_TE;
 236   ICMPBUF->icode = 0;
 237
 238   /* Calculate the ICMP checksum. */
 239   ICMPBUF->icmpchksum = 0;
 240   ICMPBUF->icmpchksum = ~uip_chksum((u16_t *)&(ICMPBUF->type), 36);
 241
 242   /* Set the IP destination address to be the source address of the
 243      original packet. */
 244   tmp16= BUF->destipaddr[0];
 245   BUF->destipaddr[0] = BUF->srcipaddr[0];
 246   BUF->srcipaddr[0] = tmp16;
 247   tmp16 = BUF->destipaddr[1];
 248   BUF->destipaddr[1] = BUF->srcipaddr[1];
 249   BUF->srcipaddr[1] = tmp16;
 250
 251   /* Set our IP address as the source address. */
 252   BUF->srcipaddr[0] = uip_hostaddr[0];
 253   BUF->srcipaddr[1] = uip_hostaddr[1];
 254
 255   /* The size of the ICMP time exceeded packet is 36 + the size of the
 256      IP header (20) = 56. */
 257   uip_len = 56;
 258   ICMPBUF->len[0] = 0;
 259   ICMPBUF->len[1] = uip_len;
 260
 261   /* Fill in the other fields in the IP header. */
 262   ICMPBUF->vhl = 0x45;
 263   ICMPBUF->tos = 0;
 264   ICMPBUF->ipoffset[0] = ICMPBUF->ipoffset[1] = 0;
 265   ICMPBUF->ttl  = UIP_TTL;
 266   ICMPBUF->proto = UIP_PROTO_ICMP;
 267
 268   /* Calculate IP checksum. */
 269   ICMPBUF->ipchksum = 0;
 270   ICMPBUF->ipchksum = ~(uip_ipchksum());
 271
 272
 273 }
 274 /*------------------------------------------------------------------------------*/
 275 /**
 276  * \internal
 277  * Register a packet in the forwarding cache so that it won't be
 278  * forwarded again.
 279  */
 280 /*------------------------------------------------------------------------------*/
 281 static void
 282 fwcache_register(void)
 283 {
 284   struct fwcache_entry *fw;
 285   int i, oldest;
 286
 287   oldest = FW_TIME;
 288   fw = NULL;
 289
 290   /* Find the oldest entry in the cache. */
 291   for(i = 0; i < FWCACHE_SIZE; ++i) {
 292     if(fwcache[i].timer == 0) {
 293       fw = &fwcache[i];
 294       break;
 295     } else if(fwcache[i].timer <= oldest) {
 296       fw = &fwcache[i];
 297       oldest = fwcache[i].timer;
 298     }
 299   }
 300
 301   fw->timer = FW_TIME;
 302   fw->ipid = BUF->ipid;
 303   fw->srcipaddr[0] = BUF->srcipaddr[0];
 304   fw->srcipaddr[1] = BUF->srcipaddr[1];
 305   fw->destipaddr[0] = BUF->destipaddr[0];
 306   fw->destipaddr[1] = BUF->destipaddr[1];
 307   fw->proto = BUF->proto;
 308 #if notdef
 309   fw->payload[0] = BUF->srcport;
 310   fw->payload[1] = BUF->destport;
 311 #endif
 312 #if UIP_REASSEMBLY > 0
 313   fw->len = BUF->len;
 314   fw->offset = BUF->ipoffset;
 315 #endif
 316 }
 317 /*------------------------------------------------------------------------------*/
 318 /**
 319  * \internal
 320  * Find a network interface for the IP packet in uip_buf.
 321  */
 322 /*------------------------------------------------------------------------------*/
 323 static struct uip_fw_netif *
 324 find_netif(void)
 325 {
 326   struct uip_fw_netif *netif;
 327
 328   /* Walk through every network interface to check for a match. */
 329   for(netif = netifs; netif != NULL; netif = netif->next) {
 330     if(ipaddr_maskcmp(BUF->destipaddr, netif->ipaddr,
 331                       netif->netmask)) {
 332       /* If there was a match, we break the loop. */
 333       return netif;
 334     }
 335   }
 336
 337   /* If no matching netif was found, we use default netif. */
 338   return defaultnetif;
 339 }
 340 /*------------------------------------------------------------------------------*/
 341 /**
 342  * Output an IP packet on the correct network interface.
 343  *
 344  * The IP packet should be present in the uip_buf buffer and its
 345  * length in the global uip_len variable.
 346  *
 347  * \retval UIP_FW_ZEROLEN Indicates that a zero-length packet
 348  * transmission was attempted and that no packet was sent.
 349  *
 350  * \retval UIP_FW_NOROUTE No suitable network interface could be found
 351  * for the outbound packet, and the packet was not sent.
 352  *
 353  * \return The return value from the actual network interface output
 354  * function is passed unmodified as a return value.
 355  */
 356 /*------------------------------------------------------------------------------*/
 357 u8_t
 358 uip_fw_output(void)
 359 {
 360   struct uip_fw_netif *netif;
 361
 362   if(uip_len == 0) {
 363     return UIP_FW_ZEROLEN;
 364   }
 365
 366   fwcache_register();
 367
 368 #if UIP_BROADCAST
 369   /* Link local broadcasts go out on all interfaces. */
 370   if(/*BUF->proto == UIP_PROTO_UDP &&*/
 371      BUF->destipaddr[0] == 0xffff &&
 372      BUF->destipaddr[1] == 0xffff) {
 373     if(defaultnetif != NULL) {
 374       defaultnetif->output();
 375     }
 376     for(netif = netifs; netif != NULL; netif = netif->next) {
 377       netif->output();
 378     }
 379     return UIP_FW_OK;
 380   }
 381 #endif /* UIP_BROADCAST */
 382
 383   netif = find_netif();
 384   /*  printf("uip_fw_output: netif %p ->output %p len %d\n", netif,
 385          netif->output,
 386          uip_len);*/
 387
 388   if(netif == NULL) {
 389     return UIP_FW_NOROUTE;
 390   }
 391   /* If we now have found a suitable network interface, we call its
 392      output function to send out the packet. */
 393   return netif->output();
 394 }
 395 /*------------------------------------------------------------------------------*/
 396 /**
 397  * Forward an IP packet in the uip_buf buffer.
 398  *
 399  *
 400  *
 401  * \return UIP_FW_FORWARDED if the packet was forwarded, UIP_FW_LOCAL if
 402  * the packet should be processed locally.
 403  */
 404 /*------------------------------------------------------------------------------*/
 405 u8_t
 406 uip_fw_forward(void)
 407 {
 408   struct fwcache_entry *fw;
 409
 410   /* First check if the packet is destined for ourselves and return 0
 411      to indicate that the packet should be processed locally. */
 412   if(BUF->destipaddr[0] == uip_hostaddr[0] &&
 413      BUF->destipaddr[1] == uip_hostaddr[1]) {
 414     return UIP_FW_LOCAL;
 415   }
 416
 417   /* If we use ping IP address configuration, and our IP address is
 418      not yet configured, we should intercept all ICMP echo packets. */
 419 #if UIP_PINGADDRCONF
 420   if((uip_hostaddr[0] | uip_hostaddr[1]) == 0 &&
 421      BUF->proto == UIP_PROTO_ICMP &&
 422      ICMPBUF->type == ICMP_ECHO) {
 423     return UIP_FW_LOCAL;
 424   }
 425 #endif /* UIP_PINGADDRCONF */
 426
 427   /* Check if the packet is in the forwarding cache already, and if so
 428      we drop it. */
 429
 430   for(fw = fwcache; fw < &fwcache[FWCACHE_SIZE]; ++fw) {
 431     if(fw->timer != 0 &&
 432 #if UIP_REASSEMBLY > 0
 433        fw->len == BUF->len &&
 434        fw->offset == BUF->ipoffset &&
 435 #endif
 436        fw->ipid == BUF->ipid &&
 437        fw->srcipaddr[0] == BUF->srcipaddr[0] &&
 438        fw->srcipaddr[1] == BUF->srcipaddr[1] &&
 439        fw->destipaddr[0] == BUF->destipaddr[0] &&
 440        fw->destipaddr[1] == BUF->destipaddr[1] &&
 441 #if notdef
 442        fw->payload[0] == BUF->srcport &&
 443        fw->payload[1] == BUF->destport &&
 444 #endif
 445        fw->proto == BUF->proto) {
 446       /* Drop packet. */
 447       return UIP_FW_FORWARDED;
 448     }
 449   }
 450
 451   /* If the TTL reaches zero we produce an ICMP time exceeded message
 452      in the uip_buf buffer and forward that packet back to the sender
 453      of the packet. */
 454   if(BUF->ttl <= 1) {
 455     /* No time exceeded for broadcasts and multicasts! */
 456     if(BUF->destipaddr[0] == 0xffff && BUF->destipaddr[1] == 0xffff) {
 457       return UIP_FW_LOCAL;
 458     }
 459     time_exceeded();
 460   }
 461
 462   /* Decrement the TTL (time-to-live) value in the IP header */
 463   BUF->ttl = BUF->ttl - 1;
 464
 465   /* Update the IP checksum. */
 466   if(BUF->ipchksum >= HTONS(0xffff - 0x0100)) {
 467     BUF->ipchksum = BUF->ipchksum + HTONS(0x0100) + 1;
 468   } else {
 469     BUF->ipchksum = BUF->ipchksum + HTONS(0x0100);
 470   }
 471
 472   if(uip_len > 0) {
 473     uip_appdata = &uip_buf[UIP_LLH_LEN + UIP_TCPIP_HLEN];
 474     uip_fw_output();
 475   }
 476
 477 #if UIP_BROADCAST
 478   if(BUF->destipaddr[0] == 0xffff && BUF->destipaddr[1] == 0xffff) {
 479     return UIP_FW_LOCAL;
 480   }
 481 #endif /* UIP_BROADCAST */
 482
 483   /* Return non-zero to indicate that the packet was forwarded and that no
 484      other processing should be made. */
 485   return UIP_FW_FORWARDED;
 486 }
 487 /*------------------------------------------------------------------------------*/
 488 /**
 489  * Register a network interface with the forwarding module.
 490  *
 491  * \param netif A pointer to the network interface that is to be
 492  * registered.
 493  */
 494 /*------------------------------------------------------------------------------*/
 495 void
 496 uip_fw_register(struct uip_fw_netif *netif)
 497 {
 498   netif->next = netifs;
 499   netifs = netif;
 500 }
 501 /*------------------------------------------------------------------------------*/
 502 /**
 503  * Register a default network interface.
 504  *
 505  * All packets that don't go out on any of the other interfaces will
 506  * be routed to the default interface.
 507  *
 508  * \param netif A pointer to the network interface that is to be
 509  * registered.
 510  */
 511 /*------------------------------------------------------------------------------*/
 512 void
 513 uip_fw_default(struct uip_fw_netif *netif)
 514 {
 515   defaultnetif = netif;
 516 }
 517 /*------------------------------------------------------------------------------*/
 518 /**
 519  * Perform periodic processing.
 520  */
 521 /*------------------------------------------------------------------------------*/
 522 void
 523 uip_fw_periodic(void)
 524 {
 525   struct fwcache_entry *fw;
 526   for(fw = fwcache; fw < &fwcache[FWCACHE_SIZE]; ++fw) {
 527     if(fw->timer > 0) {
 528       --fw->timer;
 529     }
 530   }
 531 }
 532 /*------------------------------------------------------------------------------*/