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  *              Jos Vos         :       Do accounting *before* call_in_firewall
  99  *
 100  *  
 101  *
 102  * To Fix:
 103  *              IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
 104  *              and could be made very efficient with the addition of some virtual memory hacks to permit
 105  *              the allocation of a buffer that can then be 'grown' by twiddling page tables.
 106  *              Output fragmentation wants updating along with the buffer management to use a single 
 107  *              interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
 108  *              output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
 109  *              fragmentation anyway.
 110  *
 111  *              FIXME: copy frag 0 iph to qp->iph
 112  *
 113  *              This program is free software; you can redistribute it and/or
 114  *              modify it under the terms of the GNU General Public License
 115  *              as published by the Free Software Foundation; either version
 116  *              2 of the License, or (at your option) any later version.
 117  */
 118 
 119 #include <asm/segment.h>
 120 #include <asm/system.h>
 121 #include <linux/types.h>
 122 #include <linux/kernel.h>
 123 #include <linux/sched.h>
 124 #include <linux/mm.h>
 125 #include <linux/string.h>
 126 #include <linux/errno.h>
 127 #include <linux/config.h>
 128 
 129 #include <linux/socket.h>
 130 #include <linux/sockios.h>
 131 #include <linux/in.h>
 132 #include <linux/inet.h>
 133 #include <linux/netdevice.h>
 134 #include <linux/etherdevice.h>
 135 #include <linux/proc_fs.h>
 136 #include <linux/stat.h>
 137 
 138 #include <net/snmp.h>
 139 #include <net/ip.h>
 140 #include <net/protocol.h>
 141 #include <net/route.h>
 142 #include <net/tcp.h>
 143 #include <net/udp.h>
 144 #include <linux/skbuff.h>
 145 #include <net/sock.h>
 146 #include <net/arp.h>
 147 #include <net/icmp.h>
 148 #include <net/raw.h>
 149 #include <net/checksum.h>
 150 #include <linux/igmp.h>
 151 #include <linux/ip_fw.h>
 152 #include <linux/firewall.h>
 153 #include <linux/mroute.h>
 154 #include <net/netlink.h>
 155 #ifdef CONFIG_NET_ALIAS
 156 #include <linux/net_alias.h>
 157 #endif
 158 
 159 extern int last_retran;
 160 extern void sort_send(struct sock *sk);
 161 
 162 #define min(a,b)        ((a)<(b)?(a):(b))
 163 
 164 /*
 165  *      SNMP management statistics
 166  */
 167 
 168 #ifdef CONFIG_IP_FORWARD
 169 struct ip_mib ip_statistics={1,64,};    /* Forwarding=Yes, Default TTL=64 */
 170 #else
 171 struct ip_mib ip_statistics={2,64,};    /* Forwarding=No, Default TTL=64 */
 172 #endif
 173 
 174 /*
 175  *      Handle the issuing of an ioctl() request
 176  *      for the ip device. This is scheduled to
 177  *      disappear
 178  */
 179 
 180 int ip_ioctl(struct sock *sk, int cmd, unsigned long arg)
     /* [previous][next][first][last][top][bottom][index][help] */
 181 {
 182         switch(cmd)
 183         {
 184                 default:
 185                         return(-EINVAL);
 186         }
 187 }
 188 
 189 
 190 
 191 /*
 192  *      This function receives all incoming IP datagrams.
 193  *
 194  *      On entry skb->data points to the start of the IP header and
 195  *      the MAC header has been removed.
 196  */
 197 
 198 int ip_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *pt)
     /* [previous][next][first][last][top][bottom][index][help] */
 199 {
 200         struct iphdr *iph = skb->h.iph;
 201         struct sock *raw_sk=NULL;
 202         unsigned char hash;
 203         unsigned char flag = 0;
 204         struct inet_protocol *ipprot;
 205         int brd=IS_MYADDR;
 206         struct options * opt = NULL;
 207         int is_frag=0;
 208         __u32 daddr;
 209 
 210 #ifdef CONFIG_FIREWALL
 211         int err;
 212 #endif  
 213 #ifdef CONFIG_IP_MROUTE
 214         int mroute_pkt=0;
 215 #endif  
 216 
 217 #ifdef CONFIG_NET_IPV6
 218         /* 
 219          *      Intercept IPv6 frames. We dump ST-II and invalid types just below..
 220          */
 221          
 222         if(iph->version == 6)
 223                 return ipv6_rcv(skb,dev,pt);
 224 #endif          
 225 
 226         ip_statistics.IpInReceives++;
 227 
 228         /*
 229          *      Tag the ip header of this packet so we can find it
 230          */
 231 
 232         skb->ip_hdr = iph;
 233 
 234         /*
 235          *      RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
 236          *      RFC1122: 3.1.2.3 MUST discard a frame with invalid source address [NEEDS FIXING].
 237          *
 238          *      Is the datagram acceptable?
 239          *
 240          *      1.      Length at least the size of an ip header
 241          *      2.      Version of 4
 242          *      3.      Checksums correctly. [Speed optimisation for later, skip loopback checksums]
 243          *      4.      Doesn't have a bogus length
 244          *      (5.     We ought to check for IP multicast addresses and undefined types.. does this matter ?)
 245          */
 246 
 247         if (skb->len<sizeof(struct iphdr) || iph->ihl<5 || iph->version != 4 || ip_fast_csum((unsigned char *)iph, iph->ihl) !=0
 248                 || skb->len < ntohs(iph->tot_len))
 249         {
 250                 ip_statistics.IpInHdrErrors++;
 251                 kfree_skb(skb, FREE_WRITE);
 252                 return(0);
 253         }
 254 
 255         /*
 256          *      Our transport medium may have padded the buffer out. Now we know it
 257          *      is IP we can trim to the true length of the frame.
 258          *      Note this now means skb->len holds ntohs(iph->tot_len).
 259          */
 260 
 261         skb_trim(skb,ntohs(iph->tot_len));
 262 
 263         /*
 264          *      Try to select closest <src,dst> alias device, if any.
 265          *      net_alias_dev_rcv_sel32 returns main device if it 
 266          *      fails to found other.
 267          */
 268 
 269 #ifdef CONFIG_NET_ALIAS
 270         if (iph->daddr != skb->dev->pa_addr && net_alias_has(skb->dev)) 
 271                 skb->dev = dev = net_alias_dev_rcv_sel32(skb->dev, AF_INET, iph->saddr, iph->daddr);
 272 #endif
 273 
 274         if (iph->ihl > 5) 
 275         {
 276                 skb->ip_summed = 0;
 277                 if (ip_options_compile(NULL, skb))
 278                         return(0);
 279                 opt = (struct options*)skb->proto_priv;
 280 #ifdef CONFIG_IP_NOSR
 281                 if (opt->srr) 
 282                 {
 283                         kfree_skb(skb, FREE_READ);
 284                         return -EINVAL;
 285                 }
 286 #endif                                  
 287         }
 288         
 289         /*
 290          *      Account for the packet (even if the packet is
 291          *      not accepted by the firewall!).
 292          */
 293 
 294 #ifdef CONFIG_IP_ACCT
 295         ip_fw_chk(iph,dev,ip_acct_chain,IP_FW_F_ACCEPT,1);
 296 #endif  
 297 
 298         /*
 299          *      See if the firewall wants to dispose of the packet. 
 300          */
 301         
 302 #ifdef  CONFIG_FIREWALL
 303 
 304         if ((err=call_in_firewall(PF_INET, skb, iph))<FW_ACCEPT)
 305         {
 306                 if(err==FW_REJECT)
 307                         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0, dev);
 308                 kfree_skb(skb, FREE_WRITE);
 309                 return 0;       
 310         }
 311 
 312 #endif
 313         
 314         /*
 315          *      Remember if the frame is fragmented.
 316          */
 317          
 318         if(iph->frag_off)
 319         {
 320                 if (iph->frag_off & htons(IP_MF))
 321                         is_frag|=IPFWD_FRAGMENT;
 322                 /*
 323                  *      Last fragment ?
 324                  */
 325         
 326                 if (iph->frag_off & htons(IP_OFFSET))
 327                         is_frag|=IPFWD_LASTFRAG;
 328         }
 329         
 330         /*
 331          *      Do any IP forwarding required.  chk_addr() is expensive -- avoid it someday.
 332          *
 333          *      This is inefficient. While finding out if it is for us we could also compute
 334          *      the routing table entry. This is where the great unified cache theory comes
 335          *      in as and when someone implements it
 336          *
 337          *      For most hosts over 99% of packets match the first conditional
 338          *      and don't go via ip_chk_addr. Note: brd is set to IS_MYADDR at
 339          *      function entry.
 340          */
 341         daddr = iph->daddr;
 342         if ( iph->daddr == skb->dev->pa_addr || (brd = ip_chk_addr(iph->daddr)) != 0)
 343         {
 344                 if (opt && opt->srr) 
 345                 {
 346                         int srrspace, srrptr;
 347                         __u32 nexthop;
 348                         unsigned char * optptr = ((unsigned char *)iph) + opt->srr;
 349 
 350                         if (brd != IS_MYADDR || skb->pkt_type != PACKET_HOST) 
 351                         {
 352                                 kfree_skb(skb, FREE_WRITE);
 353                                 return 0;
 354                         }
 355 
 356                         for ( srrptr=optptr[2], srrspace = optptr[1];
 357                               srrptr <= srrspace;
 358                               srrptr += 4
 359                              ) 
 360                         {
 361                                 int brd2;
 362                                 if (srrptr + 3 > srrspace) 
 363                                 {
 364                                         icmp_send(skb, ICMP_PARAMETERPROB, 0, opt->srr+2,
 365                                                   skb->dev);
 366                                         kfree_skb(skb, FREE_WRITE);
 367                                         return 0;
 368                                 }
 369                                 memcpy(&nexthop, &optptr[srrptr-1], 4);
 370                                 if ((brd2 = ip_chk_addr(nexthop)) == 0)
 371                                         break;
 372                                 if (brd2 != IS_MYADDR) 
 373                                 {
 374 
 375                                         /*
 376                                          *      ANK: should we implement weak tunneling of multicasts?
 377                                          *      Are they obsolete? DVMRP specs (RFC-1075) is old enough...
 378                                          *      [They are obsolete]
 379                                          */
 380                                         kfree_skb(skb, FREE_WRITE);
 381                                         return -EINVAL;
 382                                 }
 383                                 memcpy(&daddr, &optptr[srrptr-1], 4);
 384                         }
 385                         if (srrptr <= srrspace) 
 386                         {
 387                                 opt->srr_is_hit = 1;
 388                                 opt->is_changed = 1;
 389 #ifdef CONFIG_IP_FORWARD
 390                                 if (ip_forward(skb, dev, is_frag, nexthop))
 391                                         kfree_skb(skb, FREE_WRITE);
 392 #else
 393                                 ip_statistics.IpInAddrErrors++;
 394                                 kfree_skb(skb, FREE_WRITE);
 395 #endif
 396                                 return 0;
 397                         }
 398                 }
 399 
 400 #ifdef CONFIG_IP_MULTICAST      
 401                 if(!(dev->flags&IFF_ALLMULTI) && brd==IS_MULTICAST && iph->daddr!=IGMP_ALL_HOSTS && !(dev->flags&IFF_LOOPBACK))
 402                 {
 403                         /*
 404                          *      Check it is for one of our groups
 405                          */
 406                         struct ip_mc_list *ip_mc=dev->ip_mc_list;
 407                         do
 408                         {
 409                                 if(ip_mc==NULL)
 410                                 {       
 411                                         kfree_skb(skb, FREE_WRITE);
 412                                         return 0;
 413                                 }
 414                                 if(ip_mc->multiaddr==iph->daddr)
 415                                         break;
 416                                 ip_mc=ip_mc->next;
 417                         }
 418                         while(1);
 419                 }
 420 #endif
 421 
 422 #ifdef CONFIG_IP_MASQUERADE
 423                 /*
 424                  * Do we need to de-masquerade this fragment?
 425                  */
 426                 if (ip_fw_demasquerade(skb)) 
 427                 {
 428                         struct iphdr *iph=skb->h.iph;
 429                         if (ip_forward(skb, dev, is_frag|IPFWD_MASQUERADED, iph->daddr))
 430                                 kfree_skb(skb, FREE_WRITE);
 431                         return(0);
 432                 }
 433 #endif
 434 
 435                 /*
 436                  *      Reassemble IP fragments.
 437                  */
 438 
 439                 if(is_frag)
 440                 {
 441                         /* Defragment. Obtain the complete packet if there is one */
 442                         skb=ip_defrag(iph,skb,dev);
 443                         if(skb==NULL)
 444                                 return 0;
 445                         skb->dev = dev;
 446                         iph=skb->h.iph;
 447                 }
 448 
 449                 /*
 450                  *      Point into the IP datagram, just past the header.
 451                  */
 452 
 453                 skb->ip_hdr = iph;
 454                 skb->h.raw += iph->ihl*4;
 455 
 456 #ifdef CONFIG_IP_MROUTE         
 457                 /*
 458                  *      Check the state on multicast routing (multicast and not 224.0.0.z)
 459                  */
 460                  
 461                 if(brd==IS_MULTICAST && (iph->daddr&htonl(0xFFFFFF00))!=htonl(0xE0000000))
 462                         mroute_pkt=1;
 463 
 464 #endif
 465                 /*
 466                  *      Deliver to raw sockets. This is fun as to avoid copies we want to make no surplus copies.
 467                  *
 468                  *      RFC 1122: SHOULD pass TOS value up to the transport layer.
 469                  */
 470  
 471                 hash = iph->protocol & (SOCK_ARRAY_SIZE-1);
 472 
 473                 /* 
 474                  *      If there maybe a raw socket we must check - if not we don't care less 
 475                  */
 476                  
 477                 if((raw_sk=raw_prot.sock_array[hash])!=NULL)
 478                 {
 479                         struct sock *sknext=NULL;
 480                         struct sk_buff *skb1;
 481                         raw_sk=get_sock_raw(raw_sk, iph->protocol,  iph->saddr, iph->daddr);
 482                         if(raw_sk)      /* Any raw sockets */
 483                         {
 484                                 do
 485                                 {
 486                                         /* Find the next */
 487                                         sknext=get_sock_raw(raw_sk->next, iph->protocol, iph->saddr, iph->daddr);
 488                                         if(sknext)
 489                                                 skb1=skb_clone(skb, GFP_ATOMIC);
 490                                         else
 491                                                 break;  /* One pending raw socket left */
 492                                         if(skb1)
 493                                                 raw_rcv(raw_sk, skb1, dev, iph->saddr,daddr);
 494                                         raw_sk=sknext;
 495                                 }
 496                                 while(raw_sk!=NULL);
 497                                 
 498                                 /*
 499                                  *      Here either raw_sk is the last raw socket, or NULL if none 
 500                                  */
 501                                  
 502                                 /*
 503                                  *      We deliver to the last raw socket AFTER the protocol checks as it avoids a surplus copy 
 504                                  */
 505                         }
 506                 }
 507         
 508                 /*
 509                  *      skb->h.raw now points at the protocol beyond the IP header.
 510                  */
 511         
 512                 hash = iph->protocol & (MAX_INET_PROTOS -1);
 513                 for (ipprot = (struct inet_protocol *)inet_protos[hash];ipprot != NULL;ipprot=(struct inet_protocol *)ipprot->next)
 514                 {
 515                         struct sk_buff *skb2;
 516         
 517                         if (ipprot->protocol != iph->protocol)
 518                                 continue;
 519                        /*
 520                         *       See if we need to make a copy of it.  This will
 521                         *       only be set if more than one protocol wants it.
 522                         *       and then not for the last one. If there is a pending
 523                         *       raw delivery wait for that
 524                         */
 525         
 526 #ifdef CONFIG_IP_MROUTE
 527                         if (ipprot->copy || raw_sk || mroute_pkt)
 528 #else   
 529                         if (ipprot->copy || raw_sk)
 530 #endif                  
 531                         {
 532                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 533                                 if(skb2==NULL)
 534                                         continue;
 535                         }
 536                         else
 537                         {
 538                                 skb2 = skb;
 539                         }
 540                         flag = 1;
 541 
 542                        /*
 543                         *       Pass on the datagram to each protocol that wants it,
 544                         *       based on the datagram protocol.  We should really
 545                         *       check the protocol handler's return values here...
 546                         */
 547 
 548                         ipprot->handler(skb2, dev, opt, daddr,
 549                                 (ntohs(iph->tot_len) - (iph->ihl * 4)),
 550                                 iph->saddr, 0, ipprot);
 551                 }
 552 
 553                 /*
 554                  *      All protocols checked.
 555                  *      If this packet was a broadcast, we may *not* reply to it, since that
 556                  *      causes (proven, grin) ARP storms and a leakage of memory (i.e. all
 557                  *      ICMP reply messages get queued up for transmission...)
 558                  */
 559 
 560 #ifdef CONFIG_IP_MROUTE          
 561                 /*
 562                  *      Forward the last copy to the multicast router. If
 563                  *      there is a pending raw deliery however make a copy
 564                  *      and forward that.
 565                  */
 566                  
 567                 if(mroute_pkt)
 568                 {
 569                         flag=1;
 570                         if(raw_sk==NULL)
 571                                 ipmr_forward(skb, is_frag);
 572                         else
 573                         {
 574                                 struct sk_buff *skb2=skb_clone(skb, GFP_ATOMIC);
 575                                 if(skb2)
 576                                 {
 577                                         skb2->free=1;
 578                                         ipmr_forward(skb2, is_frag);
 579                                 }
 580                         }
 581                 }
 582 #endif          
 583 
 584                 if(raw_sk!=NULL)        /* Shift to last raw user */
 585                         raw_rcv(raw_sk, skb, dev, iph->saddr, daddr);
 586                 else if (!flag)         /* Free and report errors */
 587                 {
 588                         if (brd != IS_BROADCAST && brd!=IS_MULTICAST)
 589                                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0, dev);   
 590                         kfree_skb(skb, FREE_WRITE);
 591                 }
 592 
 593                 return(0);
 594         }
 595 
 596         /*
 597          *      Do any unicast IP forwarding required.
 598          */
 599         
 600         /*
 601          *      Don't forward multicast or broadcast frames.
 602          */
 603 
 604         if(skb->pkt_type!=PACKET_HOST || brd==IS_BROADCAST)
 605         {
 606                 kfree_skb(skb,FREE_WRITE);
 607                 return 0;
 608         }
 609 
 610         /*
 611          *      The packet is for another target. Forward the frame
 612          */
 613 
 614 #ifdef CONFIG_IP_FORWARD
 615         if (opt && opt->is_strictroute) 
 616         {
 617               icmp_send(skb, ICMP_PARAMETERPROB, 0, 16, skb->dev);
 618               kfree_skb(skb, FREE_WRITE);
 619               return -1;
 620         }
 621         if (ip_forward(skb, dev, is_frag, iph->daddr))
 622                 kfree_skb(skb, FREE_WRITE);
 623 #else
 624 /*      printk("Machine %lx tried to use us as a forwarder to %lx but we have forwarding disabled!\n",
 625                         iph->saddr,iph->daddr);*/
 626         ip_statistics.IpInAddrErrors++;
 627         kfree_skb(skb, FREE_WRITE);
 628 #endif
 629         return(0);
 630 }
 631         
 632 

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