root/net/inet/icmp.c

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DEFINITIONS

This source file includes following definitions.
  1. print_icmp
  2. icmp_send
  3. icmp_unreach
  4. icmp_redirect
  5. icmp_echo
  6. icmp_info
  7. icmp_address
  8. icmp_rcv
  9. icmp_ioctl

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Internet Control Message Protocol (ICMP)
   7  *
   8  * Version:     @(#)icmp.c      1.0.11  06/02/93
   9  *
  10  * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  13  *
  14  *              This program is free software; you can redistribute it and/or
  15  *              modify it under the terms of the GNU General Public License
  16  *              as published by the Free Software Foundation; either version
  17  *              2 of the License, or (at your option) any later version.
  18  */
  19 #include <linux/types.h>
  20 #include <linux/sched.h>
  21 #include <linux/kernel.h>
  22 #include <linux/fcntl.h>
  23 #include <linux/socket.h>
  24 #include <linux/in.h>
  25 #include "inet.h"
  26 #include "timer.h"
  27 #include "dev.h"
  28 #include "ip.h"
  29 #include "route.h"
  30 #include "protocol.h"
  31 #include "icmp.h"
  32 #include "tcp.h"
  33 #include "skbuff.h"
  34 #include "sock.h"
  35 #include <linux/errno.h>
  36 #include <linux/timer.h>
  37 #include <asm/system.h>
  38 #include <asm/segment.h>
  39 
  40 
  41 #define min(a,b)        ((a)<(b)?(a):(b))
  42 
  43 
  44 /* An array of errno for error messages from dest unreach. */
  45 struct icmp_err icmp_err_convert[] = {
  46   { ENETUNREACH,        1 },
  47   { EHOSTUNREACH,       1 },
  48   { ENOPROTOOPT,        1 },
  49   { ECONNREFUSED,       1 },
  50   { EOPNOTSUPP,         0 },
  51   { EOPNOTSUPP,         0 },
  52   { ENETUNREACH,        1 },
  53   { EHOSTDOWN,          1 },
  54   { ENONET,             1 },
  55   { ENETUNREACH,        1 },
  56   { EHOSTUNREACH,       1 },
  57   { EOPNOTSUPP,         0 },
  58   { EOPNOTSUPP,         0 }
  59 };
  60 
  61 
  62 /* Display the contents of an ICMP header. */
  63 static void
  64 print_icmp(struct icmphdr *icmph)
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  65 {
  66   if (inet_debug != DBG_ICMP) return;
  67 
  68   printk("ICMP: type = %d, code = %d, checksum = %X\n",
  69                         icmph->type, icmph->code, icmph->checksum);
  70   printk("      gateway = %s\n", in_ntoa(icmph->un.gateway));
  71 }
  72 
  73 
  74 /* Send an ICMP message. */
  75 void
  76 icmp_send(struct sk_buff *skb_in, int type, int code, struct device *dev)
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  77 {
  78   struct sk_buff *skb;
  79   struct iphdr *iph;
  80   int offset;
  81   struct icmphdr *icmph;
  82   int len;
  83 
  84   DPRINTF((DBG_ICMP, "icmp_send(skb_in = %X, type = %d, code = %d, dev=%X)\n",
  85                                                 skb_in, type, code, dev));
  86 
  87   /* Get some memory for the reply. */
  88   len = sizeof(struct sk_buff) + dev->hard_header_len +
  89         sizeof(struct iphdr) + sizeof(struct icmphdr) +
  90         sizeof(struct iphdr) + 8;       /* amount of header to return */
  91            
  92   skb = kmalloc(len, GFP_ATOMIC);
  93   if (skb == NULL) return;
  94 
  95   skb->lock = 0;
  96   skb->sk = NULL;
  97   skb->mem_addr = skb;
  98   skb->mem_len = len;
  99   len -= sizeof(struct sk_buff);
 100 
 101   /* Find the IP header. */
 102   iph = (struct iphdr *) (skb_in + 1);
 103   iph = (struct iphdr *) ((unsigned char *) iph + dev->hard_header_len);
 104 
 105   /* Build Layer 2-3 headers for message back to source. */
 106   offset = ip_build_header(skb, iph->daddr, iph->saddr,
 107                            &dev, IPPROTO_ICMP, NULL, len);
 108   if (offset < 0) {
 109         skb->sk = NULL;
 110         kfree_skb(skb, FREE_READ);
 111         return;
 112   }
 113 
 114   /* Re-adjust length according to actual IP header size. */
 115   skb->len = offset + sizeof(struct icmphdr) + 8;
 116   icmph = (struct icmphdr *) ((unsigned char *) (skb + 1) + offset);
 117   icmph->type = type;
 118   icmph->code = code;
 119   icmph->checksum = 0;
 120   icmph->un.gateway = 0;
 121   memcpy(icmph + 1, iph, sizeof(struct iphdr) + 8);
 122 
 123   DPRINTF((DBG_ICMP, ">>\n"));
 124   print_icmp(icmph);
 125 
 126   /* Send it and free it. */
 127   ip_queue_xmit(NULL, dev, skb, 1);
 128 }
 129 
 130 
 131 /* Handle ICMP_UNREACH and ICMP_QUENCH. */
 132 static void
 133 icmp_unreach(struct icmphdr *icmph, struct sk_buff *skb)
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 134 {
 135   struct inet_protocol *ipprot;
 136   struct iphdr *iph;
 137   unsigned char hash;
 138   int err;
 139 
 140   err = (icmph->type << 8) | icmph->code;
 141   iph = (struct iphdr *) (icmph + 1);
 142   switch(icmph->code & 7) {
 143         case ICMP_NET_UNREACH:
 144                 DPRINTF((DBG_ICMP, "ICMP: %s: network unreachable.\n",
 145                                                         in_ntoa(iph->daddr)));
 146                 break;
 147         case ICMP_HOST_UNREACH:
 148                 DPRINTF((DBG_ICMP, "ICMP: %s: host unreachable.\n",
 149                                                 in_ntoa(iph->daddr)));
 150                 break;
 151         case ICMP_PROT_UNREACH:
 152                 printk("ICMP: %s:%d: protocol unreachable.\n",
 153                         in_ntoa(iph->daddr), ntohs(iph->protocol));
 154                 break;
 155         case ICMP_PORT_UNREACH:
 156                 DPRINTF((DBG_ICMP, "ICMP: %s:%d: port unreachable.\n",
 157                         in_ntoa(iph->daddr), -1 /* FIXME: ntohs(iph->port) */));
 158                 break;
 159         case ICMP_FRAG_NEEDED:
 160                 printk("ICMP: %s: fragmentation needed and DF set.\n",
 161                                                         in_ntoa(iph->daddr));
 162                 break;
 163         case ICMP_SR_FAILED:
 164                 printk("ICMP: %s: Source Route Failed.\n", in_ntoa(iph->daddr));
 165                 break;
 166         default:
 167                 DPRINTF((DBG_ICMP, "ICMP: Unreachable: CODE=%d from %s\n",
 168                                 (icmph->code & 7), in_ntoa(iph->daddr)));
 169                 break;
 170   }
 171 
 172   /* Get the protocol(s). */
 173   hash = iph->protocol & (MAX_INET_PROTOS -1);
 174 
 175   /* This can change while we are doing it. */
 176   ipprot = (struct inet_protocol *) inet_protos[hash];
 177   while(ipprot != NULL) {
 178         struct inet_protocol *nextip;
 179 
 180         nextip = (struct inet_protocol *) ipprot->next;
 181 
 182         /* Pass it off to everyone who wants it. */
 183         if (iph->protocol == ipprot->protocol && ipprot->err_handler) {
 184                 ipprot->err_handler(err, (unsigned char *)(icmph + 1),
 185                                     iph->daddr, iph->saddr, ipprot);
 186         }
 187 
 188         ipprot = nextip;
 189   }
 190   skb->sk = NULL;
 191   kfree_skb(skb, FREE_READ);
 192 }
 193 
 194 
 195 /* Handle ICMP_REDIRECT. */
 196 static void
 197 icmp_redirect(struct icmphdr *icmph, struct sk_buff *skb, struct device *dev)
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 198 {
 199   struct iphdr *iph;
 200   unsigned long ip;
 201 
 202   iph = (struct iphdr *) (icmph + 1);
 203   ip = iph->daddr;
 204   switch(icmph->code & 7) {
 205         case ICMP_REDIR_NET:
 206                 rt_add((RTF_DYNAMIC | RTF_MODIFIED),
 207                         ip, icmph->un.gateway, dev);
 208                 break;
 209         case ICMP_REDIR_HOST:
 210                 rt_add((RTF_DYNAMIC | RTF_MODIFIED | RTF_HOST),
 211                         ip, icmph->un.gateway, dev);
 212                 break;
 213         case ICMP_REDIR_NETTOS:
 214         case ICMP_REDIR_HOSTTOS:
 215                 printk("ICMP: cannot handle TOS redirects yet!\n");
 216                 break;
 217         default:
 218                 DPRINTF((DBG_ICMP, "ICMP: Unreach: CODE=%d\n",
 219                                                 (icmph->code & 7)));
 220                 break;
 221   }
 222   skb->sk = NULL;
 223   kfree_skb(skb, FREE_READ);
 224 }
 225 
 226 
 227 /* Handle ICMP_ECHO ("ping") requests. */
 228 static void
 229 icmp_echo(struct icmphdr *icmph, struct sk_buff *skb, struct device *dev,
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 230           unsigned long saddr, unsigned long daddr, int len,
 231           struct options *opt)
 232 {
 233   struct icmphdr *icmphr;
 234   struct sk_buff *skb2;
 235   int size, offset;
 236 
 237   size = sizeof(struct sk_buff) + dev->hard_header_len + 64 + len;
 238   skb2 = kmalloc(size, GFP_ATOMIC);
 239   if (skb2 == NULL) {
 240         skb->sk = NULL;
 241         kfree_skb(skb, FREE_READ);
 242         return;
 243   }
 244   skb2->sk = NULL;
 245   skb2->lock = 0;
 246   skb2->mem_addr = skb2;
 247   skb2->mem_len = size;
 248 
 249   /* Build Layer 2-3 headers for message back to source */
 250   offset = ip_build_header(skb2, daddr, saddr, &dev,
 251                                 IPPROTO_ICMP, opt, len);
 252   if (offset < 0) {
 253         printk("ICMP: Could not build IP Header for ICMP ECHO Response\n");
 254         kfree_s(skb2->mem_addr, skb2->mem_len);
 255         skb->sk = NULL;
 256         kfree_skb(skb, FREE_READ);
 257         return;
 258   }
 259 
 260   /* Re-adjust length according to actual IP header size. */
 261   skb2->len = offset + len;
 262 
 263   /* Build ICMP_ECHO Response message. */
 264   icmphr = (struct icmphdr *) ((char *) (skb2 + 1) + offset);
 265   memcpy((char *) icmphr, (char *) icmph, len);
 266   icmphr->type = ICMP_ECHOREPLY;
 267   icmphr->code = 0;
 268   icmphr->checksum = 0;
 269 
 270   if (icmph->checksum) {        /* Calculate Checksum */
 271         icmphr->checksum = ip_compute_csum((void *)icmphr, len);
 272   }
 273 
 274   /* Ship it out - free it when done */
 275   ip_queue_xmit((struct sock *)NULL, dev, skb2, 1);
 276 
 277   skb->sk = NULL;
 278   kfree_skb(skb, FREE_READ);
 279 }
 280 
 281 
 282 /* Handle the ICMP INFORMATION REQUEST. */
 283 static void
 284 icmp_info(struct icmphdr *icmph, struct sk_buff *skb, struct device *dev,
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 285           unsigned long saddr, unsigned long daddr, int len,
 286           struct options *opt)
 287 {
 288   /* NOT YET */
 289   skb->sk = NULL;
 290   kfree_skb(skb, FREE_READ);
 291 }
 292 
 293 
 294 /* Handle ICMP_ADRESS_MASK requests. */
 295 static void
 296 icmp_address(struct icmphdr *icmph, struct sk_buff *skb, struct device *dev,
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 297           unsigned long saddr, unsigned long daddr, int len,
 298           struct options *opt)
 299 {
 300   struct icmphdr *icmphr;
 301   struct sk_buff *skb2;
 302   int size, offset;
 303 
 304   size = sizeof(struct sk_buff) + dev->hard_header_len + 64 + len;
 305   skb2 = kmalloc(size, GFP_ATOMIC);
 306   if (skb2 == NULL) {
 307         skb->sk = NULL;
 308         kfree_skb(skb, FREE_READ);
 309         return;
 310   }
 311   skb2->sk = NULL;
 312   skb2->lock = 0;
 313   skb2->mem_addr = skb2;
 314   skb2->mem_len = size;
 315 
 316   /* Build Layer 2-3 headers for message back to source */
 317   offset = ip_build_header(skb2, daddr, saddr, &dev,
 318                                 IPPROTO_ICMP, opt, len);
 319   if (offset < 0) {
 320         printk("ICMP: Could not build IP Header for ICMP ADDRESS Response\n");
 321         kfree_s(skb2->mem_addr, skb2->mem_len);
 322         skb->sk = NULL;
 323         kfree_skb(skb, FREE_READ);
 324         return;
 325   }
 326 
 327   /* Re-adjust length according to actual IP header size. */
 328   skb2->len = offset + len;
 329 
 330   /* Build ICMP ADDRESS MASK Response message. */
 331   icmphr = (struct icmphdr *) ((char *) (skb2 + 1) + offset);
 332   icmphr->type = ICMP_ADDRESSREPLY;
 333   icmphr->code = 0;
 334   icmphr->checksum = 0;
 335   icmphr->un.echo.id = icmph->un.echo.id;
 336   icmphr->un.echo.sequence = icmph->un.echo.sequence;
 337   memcpy((char *) (icmphr + 1), (char *) dev->pa_mask, sizeof(dev->pa_mask));
 338 
 339   if (icmph->checksum) {        /* Calculate Checksum */
 340         icmphr->checksum = ip_compute_csum((void *)icmphr, len);
 341   }
 342 
 343   /* Ship it out - free it when done */
 344   ip_queue_xmit((struct sock *)NULL, dev, skb2, 1);
 345 
 346   skb->sk = NULL;
 347   kfree_skb(skb, FREE_READ);
 348 }
 349 
 350 
 351 /* Deal with incoming ICMP packets. */
 352 int
 353 icmp_rcv(struct sk_buff *skb1, struct device *dev, struct options *opt,
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 354          unsigned long daddr, unsigned short len,
 355          unsigned long saddr, int redo, struct inet_protocol *protocol)
 356 {
 357   struct icmphdr *icmph;
 358   unsigned char *buff;
 359 
 360   /* Drop broadcast packets. */
 361   if (chk_addr(daddr) == IS_BROADCAST) {
 362         DPRINTF((DBG_ICMP, "ICMP: Discarded broadcast from %s\n",
 363                                                         in_ntoa(saddr)));
 364         skb1->sk = NULL;
 365         kfree_skb(skb1, FREE_READ);
 366         return(0);
 367   }
 368 
 369   buff = skb1->h.raw;
 370   icmph = (struct icmphdr *) buff;
 371 
 372   /* Validate the packet first */
 373   if (icmph->checksum) {        /* Checksums Enabled? */
 374         if (ip_compute_csum((unsigned char *) icmph, len)) {
 375                 /* Failed checksum! */
 376                 printk("ICMP: failed checksum from %s!\n", in_ntoa(saddr));
 377                 skb1->sk = NULL;
 378                 kfree_skb(skb1, FREE_READ);
 379                 return(0);
 380         }
 381   }
 382   print_icmp(icmph);
 383 
 384   /* Parse the ICMP message */
 385   switch(icmph->type) {
 386         case ICMP_DEST_UNREACH:
 387         case ICMP_SOURCE_QUENCH:
 388                 icmp_unreach(icmph, skb1);
 389                 return(0);
 390         case ICMP_REDIRECT:
 391                 icmp_redirect(icmph, skb1, dev);
 392                 return(0);
 393         case ICMP_ECHO: 
 394                 icmp_echo(icmph, skb1, dev, saddr, daddr, len, opt);
 395                 return 0;
 396         case ICMP_ECHOREPLY:
 397                 skb1->sk = NULL;
 398                 kfree_skb(skb1, FREE_READ);
 399                 return(0);
 400         case ICMP_INFO_REQUEST:
 401                 icmp_info(icmph, skb1, dev, saddr, daddr, len, opt);
 402                 return 0;
 403         case ICMP_INFO_REPLY:
 404                 skb1->sk = NULL;
 405                 kfree_skb(skb1, FREE_READ);
 406                 return(0);
 407         case ICMP_ADDRESS:
 408                 icmp_address(icmph, skb1, dev, saddr, daddr, len, opt);
 409                 return 0;
 410         case ICMP_ADDRESSREPLY:
 411                 skb1->sk = NULL;
 412                 kfree_skb(skb1, FREE_READ);
 413                 return(0);
 414         default:
 415                 DPRINTF((DBG_ICMP,
 416                         "ICMP: Unsupported ICMP from %s, type = 0x%X\n",
 417                                                 in_ntoa(saddr), icmph->type));
 418                 skb1->sk = NULL;
 419                 kfree_skb(skb1, FREE_READ);
 420                 return(0);
 421   }
 422   /*NOTREACHED*/
 423   skb1->sk = NULL;
 424   kfree_skb(skb1, FREE_READ);
 425   return(-1);
 426 }
 427 
 428 
 429 /* Perform any ICMP-related I/O control requests. */
 430 int
 431 icmp_ioctl(struct sock *sk, int cmd, unsigned long arg)
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 432 {
 433   switch(cmd) {
 434         case DDIOCSDBG:
 435                 return(dbg_ioctl((void *) arg, DBG_ICMP));
 436         default:
 437                 return(-EINVAL);
 438   }
 439   return(0);
 440 }

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