root/net/ipv4/ip_input.c

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DEFINITIONS

This source file includes following definitions.
  1. ip_ioctl
  2. ip_rcv

   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  *              The Internet Protocol (IP) module.
   7  *
   8  * Version:     @(#)ip.c        1.0.16b 9/1/93
   9  *
  10  * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Donald Becker, <becker@super.org>
  13  *              Alan Cox, <Alan.Cox@linux.org>
  14  *              Richard Underwood
  15  *              Stefan Becker, <stefanb@yello.ping.de>
  16  *              Jorge Cwik, <jorge@laser.satlink.net>
  17  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  18  *              
  19  *
  20  * Fixes:
  21  *              Alan Cox        :       Commented a couple of minor bits of surplus code
  22  *              Alan Cox        :       Undefining IP_FORWARD doesn't include the code
  23  *                                      (just stops a compiler warning).
  24  *              Alan Cox        :       Frames with >=MAX_ROUTE record routes, strict routes or loose routes
  25  *                                      are junked rather than corrupting things.
  26  *              Alan Cox        :       Frames to bad broadcast subnets are dumped
  27  *                                      We used to process them non broadcast and
  28  *                                      boy could that cause havoc.
  29  *              Alan Cox        :       ip_forward sets the free flag on the
  30  *                                      new frame it queues. Still crap because
  31  *                                      it copies the frame but at least it
  32  *                                      doesn't eat memory too.
  33  *              Alan Cox        :       Generic queue code and memory fixes.
  34  *              Fred Van Kempen :       IP fragment support (borrowed from NET2E)
  35  *              Gerhard Koerting:       Forward fragmented frames correctly.
  36  *              Gerhard Koerting:       Fixes to my fix of the above 8-).
  37  *              Gerhard Koerting:       IP interface addressing fix.
  38  *              Linus Torvalds  :       More robustness checks
  39  *              Alan Cox        :       Even more checks: Still not as robust as it ought to be
  40  *              Alan Cox        :       Save IP header pointer for later
  41  *              Alan Cox        :       ip option setting
  42  *              Alan Cox        :       Use ip_tos/ip_ttl settings
  43  *              Alan Cox        :       Fragmentation bogosity removed
  44  *                                      (Thanks to Mark.Bush@prg.ox.ac.uk)
  45  *              Dmitry Gorodchanin :    Send of a raw packet crash fix.
  46  *              Alan Cox        :       Silly ip bug when an overlength
  47  *                                      fragment turns up. Now frees the
  48  *                                      queue.
  49  *              Linus Torvalds/ :       Memory leakage on fragmentation
  50  *              Alan Cox        :       handling.
  51  *              Gerhard Koerting:       Forwarding uses IP priority hints
  52  *              Teemu Rantanen  :       Fragment problems.
  53  *              Alan Cox        :       General cleanup, comments and reformat
  54  *              Alan Cox        :       SNMP statistics
  55  *              Alan Cox        :       BSD address rule semantics. Also see
  56  *                                      UDP as there is a nasty checksum issue
  57  *                                      if you do things the wrong way.
  58  *              Alan Cox        :       Always defrag, moved IP_FORWARD to the config.in file
  59  *              Alan Cox        :       IP options adjust sk->priority.
  60  *              Pedro Roque     :       Fix mtu/length error in ip_forward.
  61  *              Alan Cox        :       Avoid ip_chk_addr when possible.
  62  *      Richard Underwood       :       IP multicasting.
  63  *              Alan Cox        :       Cleaned up multicast handlers.
  64  *              Alan Cox        :       RAW sockets demultiplex in the BSD style.
  65  *              Gunther Mayer   :       Fix the SNMP reporting typo
  66  *              Alan Cox        :       Always in group 224.0.0.1
  67  *      Pauline Middelink       :       Fast ip_checksum update when forwarding
  68  *                                      Masquerading support.
  69  *              Alan Cox        :       Multicast loopback error for 224.0.0.1
  70  *              Alan Cox        :       IP_MULTICAST_LOOP option.
  71  *              Alan Cox        :       Use notifiers.
  72  *              Bjorn Ekwall    :       Removed ip_csum (from slhc.c too)
  73  *              Bjorn Ekwall    :       Moved ip_fast_csum to ip.h (inline!)
  74  *              Stefan Becker   :       Send out ICMP HOST REDIRECT
  75  *      Arnt Gulbrandsen        :       ip_build_xmit
  76  *              Alan Cox        :       Per socket routing cache
  77  *              Alan Cox        :       Fixed routing cache, added header cache.
  78  *              Alan Cox        :       Loopback didnt work right in original ip_build_xmit - fixed it.
  79  *              Alan Cox        :       Only send ICMP_REDIRECT if src/dest are the same net.
  80  *              Alan Cox        :       Incoming IP option handling.
  81  *              Alan Cox        :       Set saddr on raw output frames as per BSD.
  82  *              Alan Cox        :       Stopped broadcast source route explosions.
  83  *              Alan Cox        :       Can disable source routing
  84  *              Takeshi Sone    :       Masquerading didn't work.
  85  *      Dave Bonn,Alan Cox      :       Faster IP forwarding whenever possible.
  86  *              Alan Cox        :       Memory leaks, tramples, misc debugging.
  87  *              Alan Cox        :       Fixed multicast (by popular demand 8))
  88  *              Alan Cox        :       Fixed forwarding (by even more popular demand 8))
  89  *              Alan Cox        :       Fixed SNMP statistics [I think]
  90  *      Gerhard Koerting        :       IP fragmentation forwarding fix
  91  *              Alan Cox        :       Device lock against page fault.
  92  *              Alan Cox        :       IP_HDRINCL facility.
  93  *      Werner Almesberger      :       Zero fragment bug
  94  *              Alan Cox        :       RAW IP frame length bug
  95  *              Alan Cox        :       Outgoing firewall on build_xmit
  96  *              A.N.Kuznetsov   :       IP_OPTIONS support throughout the kernel
  97  *              Alan Cox        :       Multicast routing hooks
  98  *
  99  *  
 100  *
 101  * To Fix:
 102  *              IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
 103  *              and could be made very efficient with the addition of some virtual memory hacks to permit
 104  *              the allocation of a buffer that can then be 'grown' by twiddling page tables.
 105  *              Output fragmentation wants updating along with the buffer management to use a single 
 106  *              interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
 107  *              output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
 108  *              fragmentation anyway.
 109  *
 110  *              FIXME: copy frag 0 iph to qp->iph
 111  *
 112  *              This program is free software; you can redistribute it and/or
 113  *              modify it under the terms of the GNU General Public License
 114  *              as published by the Free Software Foundation; either version
 115  *              2 of the License, or (at your option) any later version.
 116  */
 117 
 118 #include <asm/segment.h>
 119 #include <asm/system.h>
 120 #include <linux/types.h>
 121 #include <linux/kernel.h>
 122 #include <linux/sched.h>
 123 #include <linux/mm.h>
 124 #include <linux/string.h>
 125 #include <linux/errno.h>
 126 #include <linux/config.h>
 127 
 128 #include <linux/socket.h>
 129 #include <linux/sockios.h>
 130 #include <linux/in.h>
 131 #include <linux/inet.h>
 132 #include <linux/netdevice.h>
 133 #include <linux/etherdevice.h>
 134 #include <linux/proc_fs.h>
 135 #include <linux/stat.h>
 136 
 137 #include <net/snmp.h>
 138 #include <net/ip.h>
 139 #include <net/protocol.h>
 140 #include <net/route.h>
 141 #include <net/tcp.h>
 142 #include <net/udp.h>
 143 #include <linux/skbuff.h>
 144 #include <net/sock.h>
 145 #include <net/arp.h>
 146 #include <net/icmp.h>
 147 #include <net/raw.h>
 148 #include <net/checksum.h>
 149 #include <linux/igmp.h>
 150 #include <linux/ip_fw.h>
 151 #include <linux/firewall.h>
 152 #include <linux/mroute.h>
 153 #include <net/netlink.h>
 154 #ifdef CONFIG_NET_ALIAS
 155 #include <linux/net_alias.h>
 156 #endif
 157 
 158 extern int last_retran;
 159 extern void sort_send(struct sock *sk);
 160 
 161 #define min(a,b)        ((a)<(b)?(a):(b))
 162 
 163 /*
 164  *      SNMP management statistics
 165  */
 166 
 167 #ifdef CONFIG_IP_FORWARD
 168 struct ip_mib ip_statistics={1,64,};    /* Forwarding=Yes, Default TTL=64 */
 169 #else
 170 struct ip_mib ip_statistics={2,64,};    /* Forwarding=No, Default TTL=64 */
 171 #endif
 172 
 173 /*
 174  *      Handle the issuing of an ioctl() request
 175  *      for the ip device. This is scheduled to
 176  *      disappear
 177  */
 178 
 179 int ip_ioctl(struct sock *sk, int cmd, unsigned long arg)
     /* [previous][next][first][last][top][bottom][index][help] */
 180 {
 181         switch(cmd)
 182         {
 183                 default:
 184                         return(-EINVAL);
 185         }
 186 }
 187 
 188 
 189 
 190 /*
 191  *      This function receives all incoming IP datagrams.
 192  *
 193  *      On entry skb->data points to the start of the IP header and
 194  *      the MAC header has been removed.
 195  */
 196 
 197 int ip_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *pt)
     /* [previous][next][first][last][top][bottom][index][help] */
 198 {
 199         struct iphdr *iph = skb->h.iph;
 200         struct sock *raw_sk=NULL;
 201         unsigned char hash;
 202         unsigned char flag = 0;
 203         struct inet_protocol *ipprot;
 204         int brd=IS_MYADDR;
 205         struct options * opt = NULL;
 206         int is_frag=0;
 207 #ifdef CONFIG_FIREWALL
 208         int err;
 209 #endif  
 210 #ifdef CONFIG_IP_MROUTE
 211         int mroute_pkt=0;
 212 #endif  
 213 
 214 #ifdef CONFIG_NET_IPV6
 215         /* 
 216          *      Intercept IPv6 frames. We dump ST-II and invalid types just below..
 217          */
 218          
 219         if(iph->version == 6)
 220                 return ipv6_rcv(skb,dev,pt);
 221 #endif          
 222 
 223         ip_statistics.IpInReceives++;
 224 
 225         /*
 226          *      Tag the ip header of this packet so we can find it
 227          */
 228 
 229         skb->ip_hdr = iph;
 230 
 231         /*
 232          *      RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
 233          *      RFC1122: 3.1.2.3 MUST discard a frame with invalid source address [NEEDS FIXING].
 234          *
 235          *      Is the datagram acceptable?
 236          *
 237          *      1.      Length at least the size of an ip header
 238          *      2.      Version of 4
 239          *      3.      Checksums correctly. [Speed optimisation for later, skip loopback checksums]
 240          *      4.      Doesn't have a bogus length
 241          *      (5.     We ought to check for IP multicast addresses and undefined types.. does this matter ?)
 242          */
 243 
 244         if (skb->len<sizeof(struct iphdr) || iph->ihl<5 || iph->version != 4 || ip_fast_csum((unsigned char *)iph, iph->ihl) !=0
 245                 || skb->len < ntohs(iph->tot_len))
 246         {
 247                 ip_statistics.IpInHdrErrors++;
 248                 kfree_skb(skb, FREE_WRITE);
 249                 return(0);
 250         }
 251 
 252         /*
 253          *      Our transport medium may have padded the buffer out. Now we know it
 254          *      is IP we can trim to the true length of the frame.
 255          *      Note this now means skb->len holds ntohs(iph->tot_len).
 256          */
 257 
 258         skb_trim(skb,ntohs(iph->tot_len));
 259 
 260         if (iph->ihl > 5) 
 261         {
 262                 skb->ip_summed = 0;
 263                 if (ip_options_compile(NULL, skb))
 264                         return(0);
 265                 opt = (struct options*)skb->proto_priv;
 266 #ifdef CONFIG_IP_NOSR
 267                 if (opt->srr) 
 268                 {
 269                         kfree_skb(skb, FREE_READ);
 270                         return -EINVAL;
 271                 }
 272 #endif                                  
 273         }
 274         
 275         /*
 276          *      Try to select closest <src,dst> alias device, if any.
 277          *      net_alias_dev_rcv_sel32 returns main device if it 
 278          *      fails to found other.
 279          */
 280 
 281 #ifdef CONFIG_NET_ALIAS
 282         if (iph->daddr != skb->dev->pa_addr && net_alias_has(skb->dev)) 
 283                 skb->dev = dev = net_alias_dev_rcv_sel32(skb->dev, AF_INET, iph->saddr, iph->daddr);
 284 #endif
 285 
 286         /*
 287          *      See if the firewall wants to dispose of the packet. 
 288          */
 289 
 290 #ifdef  CONFIG_FIREWALL
 291         
 292         if ((err=call_in_firewall(PF_INET, skb, iph))<FW_ACCEPT)
 293         {
 294                 if(err==FW_REJECT)
 295                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0, dev);
 296                 kfree_skb(skb, FREE_WRITE);
 297                 return 0;       
 298         }
 299 
 300 #endif
 301         
 302         /*
 303          *      Remember if the frame is fragmented.
 304          */
 305          
 306         if(iph->frag_off)
 307         {
 308                 if (iph->frag_off & htons(IP_MF))
 309                         is_frag|=1;
 310                 /*
 311                  *      Last fragment ?
 312                  */
 313         
 314                 if (iph->frag_off & htons(IP_OFFSET))
 315                         is_frag|=2;
 316         }
 317         
 318         /*
 319          *      Do any IP forwarding required.  chk_addr() is expensive -- avoid it someday.
 320          *
 321          *      This is inefficient. While finding out if it is for us we could also compute
 322          *      the routing table entry. This is where the great unified cache theory comes
 323          *      in as and when someone implements it
 324          *
 325          *      For most hosts over 99% of packets match the first conditional
 326          *      and don't go via ip_chk_addr. Note: brd is set to IS_MYADDR at
 327          *      function entry.
 328          */
 329 
 330         if ( iph->daddr == skb->dev->pa_addr || (brd = ip_chk_addr(iph->daddr)) != 0)
 331         {
 332                 if (opt && opt->srr) 
 333                 {
 334                         int srrspace, srrptr;
 335                         __u32 nexthop;
 336                         unsigned char * optptr = ((unsigned char *)iph) + opt->srr;
 337 
 338                         if (brd != IS_MYADDR || skb->pkt_type != PACKET_HOST) 
 339                         {
 340                                 kfree_skb(skb, FREE_WRITE);
 341                                 return 0;
 342                         }
 343 
 344                         for ( srrptr=optptr[2], srrspace = optptr[1];
 345                               srrptr <= srrspace;
 346                               srrptr += 4
 347                              ) 
 348                         {
 349                                 int brd2;
 350                                 if (srrptr + 3 > srrspace) 
 351                                 {
 352                                         icmp_send(skb, ICMP_PARAMETERPROB, 0, opt->srr+2,
 353                                                   skb->dev);
 354                                         kfree_skb(skb, FREE_WRITE);
 355                                         return 0;
 356                                 }
 357                                 memcpy(&nexthop, &optptr[srrptr-1], 4);
 358                                 if ((brd2 = ip_chk_addr(nexthop)) == 0)
 359                                         break;
 360                                 if (brd2 != IS_MYADDR) 
 361                                 {
 362 
 363                                         /*
 364                                          *      ANK: should we implement weak tunneling of multicasts?
 365                                          *      Are they obsolete? DVMRP specs (RFC-1075) is old enough...
 366                                          *      [They are obsolete]
 367                                          */
 368                                         kfree_skb(skb, FREE_WRITE);
 369                                         return -EINVAL;
 370                                 }
 371                         }
 372                         if (srrptr <= srrspace) 
 373                         {
 374                                 opt->srr_is_hit = 1;
 375                                 opt->is_changed = 1;
 376 #ifdef CONFIG_IP_FORWARD
 377                                 if (ip_forward(skb, dev, is_frag, nexthop))
 378                                         kfree_skb(skb, FREE_WRITE);
 379 #else
 380                                 ip_statistics.IpInAddrErrors++;
 381                                 kfree_skb(skb, FREE_WRITE);
 382 #endif
 383                                 return 0;
 384                         }
 385                 }
 386 
 387 #ifdef CONFIG_IP_MULTICAST      
 388                 if(!(dev->flags&IFF_ALLMULTI) && brd==IS_MULTICAST && iph->daddr!=IGMP_ALL_HOSTS && !(dev->flags&IFF_LOOPBACK))
 389                 {
 390                         /*
 391                          *      Check it is for one of our groups
 392                          */
 393                         struct ip_mc_list *ip_mc=dev->ip_mc_list;
 394                         do
 395                         {
 396                                 if(ip_mc==NULL)
 397                                 {       
 398                                         kfree_skb(skb, FREE_WRITE);
 399                                         return 0;
 400                                 }
 401                                 if(ip_mc->multiaddr==iph->daddr)
 402                                         break;
 403                                 ip_mc=ip_mc->next;
 404                         }
 405                         while(1);
 406                 }
 407 #endif
 408 
 409 #ifdef CONFIG_IP_MASQUERADE
 410                 /*
 411                  * Do we need to de-masquerade this fragment?
 412                  */
 413                 if (ip_fw_demasquerade(skb)) 
 414                 {
 415                         struct iphdr *iph=skb->h.iph;
 416                         if (ip_forward(skb, dev, is_frag|4, iph->daddr))
 417                                 kfree_skb(skb, FREE_WRITE);
 418                         return(0);
 419                 }
 420 #endif
 421 
 422                 /*
 423                  *      Account for the packet
 424                  */
 425  
 426 #ifdef CONFIG_IP_ACCT
 427                 ip_fw_chk(iph,dev,ip_acct_chain,IP_FW_F_ACCEPT,1);
 428 #endif  
 429 
 430                 /*
 431                  *      Reassemble IP fragments.
 432                  */
 433 
 434                 if(is_frag)
 435                 {
 436                         /* Defragment. Obtain the complete packet if there is one */
 437                         skb=ip_defrag(iph,skb,dev);
 438                         if(skb==NULL)
 439                                 return 0;
 440                         skb->dev = dev;
 441                         iph=skb->h.iph;
 442                 }
 443 
 444                 /*
 445                  *      Point into the IP datagram, just past the header.
 446                  */
 447 
 448                 skb->ip_hdr = iph;
 449                 skb->h.raw += iph->ihl*4;
 450 
 451 #ifdef CONFIG_IP_MROUTE         
 452                 /*
 453                  *      Check the state on multicast routing (multicast and not 224.0.0.z)
 454                  */
 455                  
 456                 if(brd==IS_MULTICAST && (iph->daddr&htonl(0xFFFFFF00))!=htonl(0xE0000000))
 457                         mroute_pkt=1;
 458 
 459 #endif
 460                 /*
 461                  *      Deliver to raw sockets. This is fun as to avoid copies we want to make no surplus copies.
 462                  *
 463                  *      RFC 1122: SHOULD pass TOS value up to the transport layer.
 464                  */
 465  
 466                 hash = iph->protocol & (SOCK_ARRAY_SIZE-1);
 467 
 468                 /* 
 469                  *      If there maybe a raw socket we must check - if not we don't care less 
 470                  */
 471                  
 472                 if((raw_sk=raw_prot.sock_array[hash])!=NULL)
 473                 {
 474                         struct sock *sknext=NULL;
 475                         struct sk_buff *skb1;
 476                         raw_sk=get_sock_raw(raw_sk, iph->protocol,  iph->saddr, iph->daddr);
 477                         if(raw_sk)      /* Any raw sockets */
 478                         {
 479                                 do
 480                                 {
 481                                         /* Find the next */
 482                                         sknext=get_sock_raw(raw_sk->next, iph->protocol, iph->saddr, iph->daddr);
 483                                         if(sknext)
 484                                                 skb1=skb_clone(skb, GFP_ATOMIC);
 485                                         else
 486                                                 break;  /* One pending raw socket left */
 487                                         if(skb1)
 488                                                 raw_rcv(raw_sk, skb1, dev, iph->saddr,iph->daddr);
 489                                         raw_sk=sknext;
 490                                 }
 491                                 while(raw_sk!=NULL);
 492                                 
 493                                 /*
 494                                  *      Here either raw_sk is the last raw socket, or NULL if none 
 495                                  */
 496                                  
 497                                 /*
 498                                  *      We deliver to the last raw socket AFTER the protocol checks as it avoids a surplus copy 
 499                                  */
 500                         }
 501                 }
 502         
 503                 /*
 504                  *      skb->h.raw now points at the protocol beyond the IP header.
 505                  */
 506         
 507                 hash = iph->protocol & (MAX_INET_PROTOS -1);
 508                 for (ipprot = (struct inet_protocol *)inet_protos[hash];ipprot != NULL;ipprot=(struct inet_protocol *)ipprot->next)
 509                 {
 510                         struct sk_buff *skb2;
 511         
 512                         if (ipprot->protocol != iph->protocol)
 513                                 continue;
 514                        /*
 515                         *       See if we need to make a copy of it.  This will
 516                         *       only be set if more than one protocol wants it.
 517                         *       and then not for the last one. If there is a pending
 518                         *       raw delivery wait for that
 519                         */
 520         
 521 #ifdef CONFIG_IP_MROUTE
 522                         if (ipprot->copy || raw_sk || mroute_pkt)
 523 #else   
 524                         if (ipprot->copy || raw_sk)
 525 #endif                  
 526                         {
 527                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 528                                 if(skb2==NULL)
 529                                         continue;
 530                         }
 531                         else
 532                         {
 533                                 skb2 = skb;
 534                         }
 535                         flag = 1;
 536 
 537                        /*
 538                         *       Pass on the datagram to each protocol that wants it,
 539                         *       based on the datagram protocol.  We should really
 540                         *       check the protocol handler's return values here...
 541                         */
 542 
 543                         ipprot->handler(skb2, dev, opt, iph->daddr,
 544                                 (ntohs(iph->tot_len) - (iph->ihl * 4)),
 545                                 iph->saddr, 0, ipprot);
 546                 }
 547 
 548                 /*
 549                  *      All protocols checked.
 550                  *      If this packet was a broadcast, we may *not* reply to it, since that
 551                  *      causes (proven, grin) ARP storms and a leakage of memory (i.e. all
 552                  *      ICMP reply messages get queued up for transmission...)
 553                  */
 554 
 555 #ifdef CONFIG_IP_MROUTE          
 556                 /*
 557                  *      Forward the last copy to the multicast router. If
 558                  *      there is a pending raw deliery however make a copy
 559                  *      and forward that.
 560                  */
 561                  
 562                 if(mroute_pkt)
 563                 {
 564                         flag=1;
 565                         if(raw_sk==NULL)
 566                                 ipmr_forward(skb, is_frag);
 567                         else
 568                         {
 569                                 struct sk_buff *skb2=skb_clone(skb, GFP_ATOMIC);
 570                                 if(skb2)
 571                                 {
 572                                         skb2->free=1;
 573                                         ipmr_forward(skb2, is_frag);
 574                                 }
 575                         }
 576                 }
 577 #endif          
 578 
 579                 if(raw_sk!=NULL)        /* Shift to last raw user */
 580                         raw_rcv(raw_sk, skb, dev, iph->saddr, iph->daddr);
 581                 else if (!flag)         /* Free and report errors */
 582                 {
 583                         if (brd != IS_BROADCAST && brd!=IS_MULTICAST)
 584                                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0, dev);   
 585                         kfree_skb(skb, FREE_WRITE);
 586                 }
 587 
 588                 return(0);
 589         }
 590 
 591         /*
 592          *      Do any unicast IP forwarding required.
 593          */
 594         
 595         /*
 596          *      Don't forward multicast or broadcast frames.
 597          */
 598 
 599         if(skb->pkt_type!=PACKET_HOST || brd==IS_BROADCAST)
 600         {
 601                 kfree_skb(skb,FREE_WRITE);
 602                 return 0;
 603         }
 604 
 605         /*
 606          *      The packet is for another target. Forward the frame
 607          */
 608 
 609 #ifdef CONFIG_IP_FORWARD
 610         if (opt && opt->is_strictroute) 
 611         {
 612               icmp_send(skb, ICMP_PARAMETERPROB, 0, 16, skb->dev);
 613               kfree_skb(skb, FREE_WRITE);
 614               return -1;
 615         }
 616         if (ip_forward(skb, dev, is_frag, iph->daddr))
 617                 kfree_skb(skb, FREE_WRITE);
 618 #else
 619 /*      printk("Machine %lx tried to use us as a forwarder to %lx but we have forwarding disabled!\n",
 620                         iph->saddr,iph->daddr);*/
 621         ip_statistics.IpInAddrErrors++;
 622         kfree_skb(skb, FREE_WRITE);
 623 #endif
 624         return(0);
 625 }
 626         
 627 

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