root/net/ipv4/ip_output.c

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DEFINITIONS

This source file includes following definitions.
  1. ip_loopback
  2. ip_send
  3. ip_send_room
  4. ip_build_header
  5. ip_send_check
  6. ip_queue_xmit
  7. ip_build_xmit
  8. ip_netlink_msg
  9. ip_rt_event
  10. ip_init

   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) output 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  *      See ip_input.c for original log
  20  *
  21  *      Fixes:
  22  *              Alan Cox        :       Missing nonblock feature in ip_build_xmit.
  23  *              Mike Kilburn    :       htons() missing in ip_build_xmit.
  24  */
  25 
  26 #include <asm/segment.h>
  27 #include <asm/system.h>
  28 #include <linux/types.h>
  29 #include <linux/kernel.h>
  30 #include <linux/sched.h>
  31 #include <linux/mm.h>
  32 #include <linux/string.h>
  33 #include <linux/errno.h>
  34 #include <linux/config.h>
  35 
  36 #include <linux/socket.h>
  37 #include <linux/sockios.h>
  38 #include <linux/in.h>
  39 #include <linux/inet.h>
  40 #include <linux/netdevice.h>
  41 #include <linux/etherdevice.h>
  42 #include <linux/proc_fs.h>
  43 #include <linux/stat.h>
  44 
  45 #include <net/snmp.h>
  46 #include <net/ip.h>
  47 #include <net/protocol.h>
  48 #include <net/route.h>
  49 #include <net/tcp.h>
  50 #include <net/udp.h>
  51 #include <linux/skbuff.h>
  52 #include <net/sock.h>
  53 #include <net/arp.h>
  54 #include <net/icmp.h>
  55 #include <net/raw.h>
  56 #include <net/checksum.h>
  57 #include <linux/igmp.h>
  58 #include <linux/ip_fw.h>
  59 #include <linux/firewall.h>
  60 #include <linux/mroute.h>
  61 #include <net/netlink.h>
  62 
  63 /*
  64  *      Loop a packet back to the sender.
  65  */
  66  
  67 static void ip_loopback(struct device *old_dev, struct sk_buff *skb)
     /* [previous][next][first][last][top][bottom][index][help] */
  68 {
  69         struct device *dev=&loopback_dev;
  70         int len=ntohs(skb->ip_hdr->tot_len);
  71         struct sk_buff *newskb=dev_alloc_skb(len+dev->hard_header_len+15);
  72         
  73         if(newskb==NULL)
  74                 return;
  75                 
  76         newskb->link3=NULL;
  77         newskb->sk=NULL;
  78         newskb->dev=dev;
  79         newskb->saddr=skb->saddr;
  80         newskb->daddr=skb->daddr;
  81         newskb->raddr=skb->raddr;
  82         newskb->free=1;
  83         newskb->lock=0;
  84         newskb->users=0;
  85         newskb->pkt_type=skb->pkt_type;
  86         
  87         /*
  88          *      Put a MAC header on the packet
  89          */
  90         ip_send(NULL,newskb, skb->ip_hdr->daddr, len, dev, skb->ip_hdr->saddr);
  91         /*
  92          *      Add the rest of the data space. 
  93          */
  94         newskb->ip_hdr=(struct iphdr *)skb_put(newskb, len);
  95         memcpy(newskb->proto_priv, skb->proto_priv, sizeof(skb->proto_priv));
  96 
  97         /*
  98          *      Copy the data
  99          */
 100         memcpy(newskb->ip_hdr,skb->ip_hdr,len);
 101 
 102         /* Recurse. The device check against IFF_LOOPBACK will stop infinite recursion */
 103                 
 104         /*printk("Loopback output queued [%lX to %lX].\n", newskb->ip_hdr->saddr,newskb->ip_hdr->daddr);*/
 105         ip_queue_xmit(NULL, dev, newskb, 1);
 106 }
 107 
 108 
 109 
 110 /*
 111  *      Take an skb, and fill in the MAC header.
 112  */
 113 
 114 int ip_send(struct rtable * rt, struct sk_buff *skb, __u32 daddr, int len, struct device *dev, __u32 saddr)
     /* [previous][next][first][last][top][bottom][index][help] */
 115 {
 116         int mac = 0;
 117 
 118         skb->dev = dev;
 119         skb->arp = 1;
 120         skb->protocol = htons(ETH_P_IP);
 121         if (dev->hard_header)
 122         {
 123                 /*
 124                  *      Build a hardware header. Source address is our mac, destination unknown
 125                  *      (rebuild header will sort this out)
 126                  */
 127                 skb_reserve(skb,(dev->hard_header_len+15)&~15); /* 16 byte aligned IP headers are good */
 128                 if (rt && dev == rt->rt_dev && rt->rt_hh)
 129                 {
 130                         memcpy(skb_push(skb,dev->hard_header_len),rt->rt_hh->hh_data,dev->hard_header_len);
 131                         if (rt->rt_hh->hh_uptodate)
 132                                 return dev->hard_header_len;
 133 #if RT_CACHE_DEBUG >= 2
 134                         printk("ip_send: hh miss %08x via %08x\n", daddr, rt->rt_gateway);
 135 #endif
 136                         skb->arp = 0;
 137                         skb->raddr = daddr;
 138                         return -dev->hard_header_len;
 139                 }
 140                 mac = dev->hard_header(skb, dev, ETH_P_IP, NULL, NULL, len);
 141                 if (mac < 0)
 142                 {
 143                         mac = -mac;
 144                         skb->arp = 0;
 145                         skb->raddr = daddr;     /* next routing address */
 146                 }
 147         }
 148         return mac;
 149 }
 150 
 151 static int ip_send_room(struct rtable * rt, struct sk_buff *skb, __u32 daddr, int len, struct device *dev, __u32 saddr)
     /* [previous][next][first][last][top][bottom][index][help] */
 152 {
 153         int mac = 0;
 154 
 155         skb->dev = dev;
 156         skb->arp = 1;
 157         skb->protocol = htons(ETH_P_IP);
 158         if (dev->hard_header)
 159         {
 160                 skb_reserve(skb,MAX_HEADER);
 161                 if (rt && dev == rt->rt_dev && rt->rt_hh)
 162                 {
 163                         memcpy(skb_push(skb,dev->hard_header_len),rt->rt_hh->hh_data,dev->hard_header_len);
 164                         if (rt->rt_hh->hh_uptodate)
 165                                 return dev->hard_header_len;
 166 #if RT_CACHE_DEBUG >= 2
 167                         printk("ip_send_room: hh miss %08x via %08x\n", daddr, rt->rt_gateway);
 168 #endif
 169                         skb->arp = 0;
 170                         skb->raddr = daddr;
 171                         return -dev->hard_header_len;
 172                 }
 173                 mac = dev->hard_header(skb, dev, ETH_P_IP, NULL, NULL, len);
 174                 if (mac < 0)
 175                 {
 176                         mac = -mac;
 177                         skb->arp = 0;
 178                         skb->raddr = daddr;     /* next routing address */
 179                 }
 180         }
 181         return mac;
 182 }
 183 
 184 int ip_id_count = 0;
 185 
 186 /*
 187  * This routine builds the appropriate hardware/IP headers for
 188  * the routine.  It assumes that if *dev != NULL then the
 189  * protocol knows what it's doing, otherwise it uses the
 190  * routing/ARP tables to select a device struct.
 191  */
 192 int ip_build_header(struct sk_buff *skb, __u32 saddr, __u32 daddr,
     /* [previous][next][first][last][top][bottom][index][help] */
 193                 struct device **dev, int type, struct options *opt,
 194                 int len, int tos, int ttl, struct rtable ** rp)
 195 {
 196         struct rtable *rt;
 197         __u32 raddr;
 198         int tmp;
 199         struct iphdr *iph;
 200         __u32 final_daddr = daddr;
 201 
 202 
 203         if (opt && opt->srr)
 204                 daddr = opt->faddr;
 205 
 206         /*
 207          *      See if we need to look up the device.
 208          */
 209 
 210 #ifdef CONFIG_IP_MULTICAST      
 211         if(MULTICAST(daddr) && *dev==NULL && skb->sk && *skb->sk->ip_mc_name)
 212                 *dev=dev_get(skb->sk->ip_mc_name);
 213 #endif
 214         if (rp)
 215         {
 216                 rt = ip_check_route(rp, daddr, skb->localroute);
 217                 /*
 218                  * If rp != NULL rt_put following below should not
 219                  * release route, so that...
 220                  */
 221                 if (rt)
 222                         ATOMIC_INCR(&rt->rt_refcnt);
 223         }
 224         else
 225                 rt = ip_rt_route(daddr, skb->localroute);
 226 
 227 
 228         if (*dev == NULL)
 229         {
 230                 if (rt == NULL)
 231                 {
 232                         ip_statistics.IpOutNoRoutes++;
 233                         return(-ENETUNREACH);
 234                 }
 235 
 236                 *dev = rt->rt_dev;
 237         }
 238 
 239         if ((LOOPBACK(saddr) && !LOOPBACK(daddr)) || !saddr)
 240                 saddr = rt ? rt->rt_src : (*dev)->pa_addr;
 241 
 242         raddr = rt ? rt->rt_gateway : 0;
 243 
 244         if (opt && opt->is_strictroute && rt && (rt->rt_flags & RTF_GATEWAY))
 245         {
 246                 ip_rt_put(rt);
 247                 ip_statistics.IpOutNoRoutes++;
 248                 return -ENETUNREACH;
 249         }
 250 
 251         /*
 252          *      No gateway so aim at the real destination
 253          */
 254 
 255         if (raddr == 0)
 256                 raddr = daddr;
 257 
 258         /*
 259          *      Now build the MAC header.
 260          */
 261 
 262         if (type==IPPROTO_TCP)
 263                 tmp = ip_send_room(rt, skb, raddr, len, *dev, saddr);
 264         else
 265                 tmp = ip_send(rt, skb, raddr, len, *dev, saddr);
 266 
 267         ip_rt_put(rt);
 268 
 269         /*
 270          *      Book keeping
 271          */
 272 
 273         skb->dev = *dev;
 274         skb->saddr = saddr;
 275 
 276         /*
 277          *      Now build the IP header.
 278          */
 279 
 280         /*
 281          *      If we are using IPPROTO_RAW, then we don't need an IP header, since
 282          *      one is being supplied to us by the user
 283          */
 284 
 285         if(type == IPPROTO_RAW)
 286                 return (tmp);
 287 
 288         /*
 289          *      Build the IP addresses
 290          */
 291          
 292         if (opt)
 293                 iph=(struct iphdr *)skb_put(skb,sizeof(struct iphdr) + opt->optlen);
 294         else
 295                 iph=(struct iphdr *)skb_put(skb,sizeof(struct iphdr));
 296 
 297         iph->version  = 4;
 298         iph->ihl      = 5;
 299         iph->tos      = tos;
 300         iph->frag_off = 0;
 301         iph->ttl      = ttl;
 302         iph->daddr    = daddr;
 303         iph->saddr    = saddr;
 304         iph->protocol = type;
 305         skb->ip_hdr   = iph;
 306 
 307         if (!opt || !opt->optlen)
 308                 return sizeof(struct iphdr) + tmp;
 309         iph->ihl += opt->optlen>>2;
 310         ip_options_build(skb, opt, final_daddr, (*dev)->pa_addr, 0);
 311         return iph->ihl*4 + tmp;
 312 }
 313 
 314 
 315 /*
 316  *      Generate a checksum for an outgoing IP datagram.
 317  */
 318 
 319 void ip_send_check(struct iphdr *iph)
     /* [previous][next][first][last][top][bottom][index][help] */
 320 {
 321         iph->check = 0;
 322         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
 323 }
 324 
 325 /*
 326  * Queues a packet to be sent, and starts the transmitter
 327  * if necessary.  if free = 1 then we free the block after
 328  * transmit, otherwise we don't. If free==2 we not only
 329  * free the block but also don't assign a new ip seq number.
 330  * This routine also needs to put in the total length,
 331  * and compute the checksum
 332  */
 333 
 334 void ip_queue_xmit(struct sock *sk, struct device *dev,
     /* [previous][next][first][last][top][bottom][index][help] */
 335               struct sk_buff *skb, int free)
 336 {
 337         struct iphdr *iph;
 338 /*      unsigned char *ptr;*/
 339 
 340         /* Sanity check */
 341         if (dev == NULL)
 342         {
 343                 NETDEBUG(printk("IP: ip_queue_xmit dev = NULL\n"));
 344                 return;
 345         }
 346 
 347         IS_SKB(skb);
 348 
 349         /*
 350          *      Do some book-keeping in the packet for later
 351          */
 352 
 353 
 354         skb->dev = dev;
 355         skb->when = jiffies;
 356 
 357         /*
 358          *      Find the IP header and set the length. This is bad
 359          *      but once we get the skb data handling code in the
 360          *      hardware will push its header sensibly and we will
 361          *      set skb->ip_hdr to avoid this mess and the fixed
 362          *      header length problem
 363          */
 364 
 365         iph = skb->ip_hdr;
 366         iph->tot_len = htons(skb->len-(((unsigned char *)iph)-skb->data));
 367 
 368 #ifdef CONFIG_FIREWALL
 369         if(call_out_firewall(PF_INET, skb, iph) < FW_ACCEPT)
 370                 /* just don't send this packet */
 371                 return;
 372 #endif  
 373 
 374         /*
 375          *      No reassigning numbers to fragments...
 376          */
 377 
 378         if(free!=2)
 379                 iph->id      = htons(ip_id_count++);
 380         else
 381                 free=1;
 382 
 383         /* All buffers without an owner socket get freed */
 384         if (sk == NULL)
 385                 free = 1;
 386 
 387         skb->free = free;
 388 
 389         /*
 390          *      Do we need to fragment. Again this is inefficient.
 391          *      We need to somehow lock the original buffer and use
 392          *      bits of it.
 393          */
 394 
 395         if(ntohs(iph->tot_len)> dev->mtu)
 396         {
 397                 ip_fragment(sk,skb,dev,0);
 398                 IS_SKB(skb);
 399                 kfree_skb(skb,FREE_WRITE);
 400                 return;
 401         }
 402 
 403         /*
 404          *      Add an IP checksum
 405          */
 406 
 407         ip_send_check(iph);
 408 
 409         /*
 410          *      Print the frame when debugging
 411          */
 412 
 413         /*
 414          *      More debugging. You cannot queue a packet already on a list
 415          *      Spot this and moan loudly.
 416          */
 417         if (skb->next != NULL)
 418         {
 419                 NETDEBUG(printk("ip_queue_xmit: next != NULL\n"));
 420                 skb_unlink(skb);
 421         }
 422 
 423         /*
 424          *      If a sender wishes the packet to remain unfreed
 425          *      we add it to his send queue. This arguably belongs
 426          *      in the TCP level since nobody else uses it. BUT
 427          *      remember IPng might change all the rules.
 428          */
 429 
 430         if (!free)
 431         {
 432                 unsigned long flags;
 433                 /* The socket now has more outstanding blocks */
 434 
 435                 sk->packets_out++;
 436 
 437                 /* Protect the list for a moment */
 438                 save_flags(flags);
 439                 cli();
 440 
 441                 if (skb->link3 != NULL)
 442                 {
 443                         NETDEBUG(printk("ip.c: link3 != NULL\n"));
 444                         skb->link3 = NULL;
 445                 }
 446                 if (sk->send_head == NULL)
 447                 {
 448                         sk->send_tail = skb;
 449                         sk->send_head = skb;
 450                 }
 451                 else
 452                 {
 453                         sk->send_tail->link3 = skb;
 454                         sk->send_tail = skb;
 455                 }
 456                 /* skb->link3 is NULL */
 457 
 458                 /* Interrupt restore */
 459                 restore_flags(flags);
 460         }
 461         else
 462                 /* Remember who owns the buffer */
 463                 skb->sk = sk;
 464 
 465         /*
 466          *      If the indicated interface is up and running, send the packet.
 467          */
 468          
 469         ip_statistics.IpOutRequests++;
 470 #ifdef CONFIG_IP_ACCT
 471         ip_fw_chk(iph,dev,ip_acct_chain,IP_FW_F_ACCEPT,1);
 472 #endif  
 473         
 474 #ifdef CONFIG_IP_MULTICAST      
 475 
 476         /*
 477          *      Multicasts are looped back for other local users
 478          */
 479          
 480         if (MULTICAST(iph->daddr) && !(dev->flags&IFF_LOOPBACK))
 481         {
 482                 if(sk==NULL || sk->ip_mc_loop)
 483                 {
 484                         if(iph->daddr==IGMP_ALL_HOSTS || (dev->flags&IFF_ALLMULTI))
 485                         {
 486                                 ip_loopback(dev,skb);
 487                         }
 488                         else
 489                         {
 490                                 struct ip_mc_list *imc=dev->ip_mc_list;
 491                                 while(imc!=NULL)
 492                                 {
 493                                         if(imc->multiaddr==iph->daddr)
 494                                         {
 495                                                 ip_loopback(dev,skb);
 496                                                 break;
 497                                         }
 498                                         imc=imc->next;
 499                                 }
 500                         }
 501                 }
 502                 /* Multicasts with ttl 0 must not go beyond the host */
 503                 
 504                 if(skb->ip_hdr->ttl==0)
 505                 {
 506                         kfree_skb(skb, FREE_READ);
 507                         return;
 508                 }
 509         }
 510 #endif
 511         if((dev->flags&IFF_BROADCAST) && (iph->daddr==dev->pa_brdaddr||iph->daddr==0xFFFFFFFF) && !(dev->flags&IFF_LOOPBACK))
 512                 ip_loopback(dev,skb);
 513                 
 514         if (dev->flags & IFF_UP)
 515         {
 516                 /*
 517                  *      If we have an owner use its priority setting,
 518                  *      otherwise use NORMAL
 519                  */
 520 
 521                 if (sk != NULL)
 522                 {
 523                         dev_queue_xmit(skb, dev, sk->priority);
 524                 }
 525                 else
 526                 {
 527                         dev_queue_xmit(skb, dev, SOPRI_NORMAL);
 528                 }
 529         }
 530         else
 531         {
 532                 if(sk)
 533                         sk->err = ENETDOWN;
 534                 ip_statistics.IpOutDiscards++;
 535                 if (free)
 536                         kfree_skb(skb, FREE_WRITE);
 537         }
 538 }
 539 
 540 
 541 /*
 542  *      Build and send a packet, with as little as one copy
 543  *
 544  *      Doesn't care much about ip options... option length can be
 545  *      different for fragment at 0 and other fragments.
 546  *
 547  *      Note that the fragment at the highest offset is sent first,
 548  *      so the getfrag routine can fill in the TCP/UDP checksum header
 549  *      field in the last fragment it sends... actually it also helps
 550  *      the reassemblers, they can put most packets in at the head of
 551  *      the fragment queue, and they know the total size in advance. This
 552  *      last feature will measurable improve the Linux fragment handler.
 553  *
 554  *      The callback has five args, an arbitrary pointer (copy of frag),
 555  *      the source IP address (may depend on the routing table), the 
 556  *      destination adddress (char *), the offset to copy from, and the
 557  *      length to be copied.
 558  * 
 559  */
 560 
 561 int ip_build_xmit(struct sock *sk,
     /* [previous][next][first][last][top][bottom][index][help] */
 562                    void getfrag (const void *,
 563                                  __u32,
 564                                  char *,
 565                                  unsigned int,  
 566                                  unsigned int),
 567                    const void *frag,
 568                    unsigned short int length,
 569                    __u32 daddr,
 570                    __u32 user_saddr,
 571                    struct options * opt,
 572                    int flags,
 573                    int type,
 574                    int noblock) 
 575 {
 576         struct rtable *rt;
 577         unsigned int fraglen, maxfraglen, fragheaderlen;
 578         int offset, mf;
 579         __u32 saddr;
 580         unsigned short id;
 581         struct iphdr *iph;
 582         __u32 raddr;
 583         struct device *dev = NULL;
 584         struct hh_cache * hh=NULL;
 585         int nfrags=0;
 586         __u32 true_daddr = daddr;
 587 
 588         if (opt && opt->srr && !sk->ip_hdrincl)
 589           daddr = opt->faddr;
 590         
 591         ip_statistics.IpOutRequests++;
 592 
 593 #ifdef CONFIG_IP_MULTICAST      
 594         if(sk && MULTICAST(daddr) && *sk->ip_mc_name)
 595         {
 596                 dev=dev_get(sk->ip_mc_name);
 597                 if(!dev)
 598                         return -ENODEV;
 599                 rt=NULL;
 600                 if (sk->saddr && (!LOOPBACK(sk->saddr) || LOOPBACK(daddr)))
 601                         saddr = sk->saddr;
 602                 else
 603                         saddr = dev->pa_addr;
 604         }
 605         else
 606         {
 607 #endif  
 608                 rt = ip_check_route(&sk->ip_route_cache, daddr,
 609                                     sk->localroute || (flags&MSG_DONTROUTE) ||
 610                                     (opt && opt->is_strictroute));
 611                 if (rt == NULL) 
 612                 {
 613                         ip_statistics.IpOutNoRoutes++;
 614                         return(-ENETUNREACH);
 615                 }
 616                 saddr = rt->rt_src;
 617 
 618                 hh = rt->rt_hh;
 619         
 620                 if (sk->saddr && (!LOOPBACK(sk->saddr) || LOOPBACK(daddr)))
 621                         saddr = sk->saddr;
 622                         
 623                 dev=rt->rt_dev;
 624 #ifdef CONFIG_IP_MULTICAST
 625         }
 626         if (rt && !dev)
 627                 dev = rt->rt_dev;
 628 #endif          
 629         if (user_saddr)
 630                 saddr = user_saddr;
 631 
 632         raddr = rt ? rt->rt_gateway : daddr;
 633         /*
 634          *      Now compute the buffer space we require
 635          */ 
 636          
 637         /*
 638          *      Try the simple case first. This leaves broadcast, multicast, fragmented frames, and by
 639          *      choice RAW frames within 20 bytes of maximum size(rare) to the long path
 640          */
 641 
 642         length += sizeof(struct iphdr);
 643         if (!sk->ip_hdrincl && opt) 
 644                 length += opt->optlen;
 645 
 646         if(length <= dev->mtu && !MULTICAST(daddr) && daddr!=0xFFFFFFFF && daddr!=dev->pa_brdaddr)
 647         {       
 648                 int error;
 649                 struct sk_buff *skb=sock_alloc_send_skb(sk, length+15+dev->hard_header_len,0, noblock, &error);
 650                 if(skb==NULL)
 651                 {
 652                         ip_statistics.IpOutDiscards++;
 653                         return error;
 654                 }
 655                 skb->dev=dev;
 656                 skb->protocol = htons(ETH_P_IP);
 657                 skb->free=1;
 658                 skb->when=jiffies;
 659                 skb->sk=sk;
 660                 skb->arp=0;
 661                 skb->saddr=saddr;
 662                 skb->raddr = raddr;
 663                 skb_reserve(skb,(dev->hard_header_len+15)&~15);
 664                 if (hh)
 665                 {
 666                         skb->arp=1;
 667                         memcpy(skb_push(skb,dev->hard_header_len),hh->hh_data,dev->hard_header_len);
 668                         if (!hh->hh_uptodate)
 669                         {
 670                                 skb->arp = 0;
 671 #if RT_CACHE_DEBUG >= 2
 672                                 printk("ip_build_xmit: hh miss %08x via %08x\n", rt->rt_dst, rt->rt_gateway);
 673 #endif                          
 674                         }
 675                 }
 676                 else if(dev->hard_header)
 677                 {
 678                         if(dev->hard_header(skb,dev,ETH_P_IP,NULL,NULL,0)>0)
 679                                 skb->arp=1;
 680                 }
 681                 else
 682                         skb->arp=1;
 683                 skb->ip_hdr=iph=(struct iphdr *)skb_put(skb,length);
 684                 dev_lock_list();
 685                 if(!sk->ip_hdrincl)
 686                 {
 687                         iph->version=4;
 688                         iph->ihl=5;
 689                         iph->tos=sk->ip_tos;
 690                         iph->tot_len = htons(length);
 691                         iph->id=htons(ip_id_count++);
 692                         iph->frag_off = 0;
 693                         iph->ttl=sk->ip_ttl;
 694                         iph->protocol=type;
 695                         iph->saddr=saddr;
 696                         iph->daddr=daddr;
 697                         if (opt) 
 698                         {
 699                                 iph->ihl += opt->optlen>>2;
 700                                 ip_options_build(skb, opt,
 701                                                  true_daddr, dev->pa_addr, 0);
 702                         }
 703                         iph->check=0;
 704                         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
 705                         getfrag(frag,saddr,((char *)iph)+iph->ihl*4,0, length-iph->ihl*4);
 706                 }
 707                 else
 708                         getfrag(frag,saddr,(void *)iph,0,length-20);
 709                 dev_unlock_list();
 710 #ifdef CONFIG_FIREWALL
 711                 if(call_out_firewall(PF_INET, skb, iph)< FW_ACCEPT)
 712                 {
 713                         kfree_skb(skb, FREE_WRITE);
 714                         return -EPERM;
 715                 }
 716 #endif
 717 #ifdef CONFIG_IP_ACCT
 718                 ip_fw_chk(iph,dev,ip_acct_chain, IP_FW_F_ACCEPT,1);
 719 #endif          
 720                 if(dev->flags&IFF_UP)
 721                         dev_queue_xmit(skb,dev,sk->priority);
 722                 else
 723                 {
 724                         ip_statistics.IpOutDiscards++;
 725                         kfree_skb(skb, FREE_WRITE);
 726                 }
 727                 return 0;
 728         }
 729         length -= sizeof(struct iphdr);
 730         if (sk && !sk->ip_hdrincl && opt) 
 731         {
 732                 length -= opt->optlen;
 733                 fragheaderlen = dev->hard_header_len + sizeof(struct iphdr) + opt->optlen;
 734                 maxfraglen = ((dev->mtu-sizeof(struct iphdr)-opt->optlen) & ~7) + fragheaderlen;
 735         }
 736         else 
 737         {
 738                 fragheaderlen = dev->hard_header_len;
 739                 if(!sk->ip_hdrincl)
 740                         fragheaderlen += 20;
 741                 
 742                 /*
 743                  *      Fragheaderlen is the size of 'overhead' on each buffer. Now work
 744                  *      out the size of the frames to send.
 745                  */
 746          
 747                 maxfraglen = ((dev->mtu-20) & ~7) + fragheaderlen;
 748         }
 749         
 750         /*
 751          *      Start at the end of the frame by handling the remainder.
 752          */
 753          
 754         offset = length - (length % (maxfraglen - fragheaderlen));
 755         
 756         /*
 757          *      Amount of memory to allocate for final fragment.
 758          */
 759          
 760         fraglen = length - offset + fragheaderlen;
 761         
 762         if(length-offset==0)
 763         {
 764                 fraglen = maxfraglen;
 765                 offset -= maxfraglen-fragheaderlen;
 766         }
 767         
 768         
 769         /*
 770          *      The last fragment will not have MF (more fragments) set.
 771          */
 772          
 773         mf = 0;
 774 
 775         /*
 776          *      Can't fragment raw packets 
 777          */
 778          
 779         if (sk->ip_hdrincl && offset > 0)
 780                 return(-EMSGSIZE);
 781 
 782         /*
 783          *      Lock the device lists.
 784          */
 785 
 786         dev_lock_list();
 787         
 788         /*
 789          *      Get an identifier
 790          */
 791          
 792         id = htons(ip_id_count++);
 793 
 794         /*
 795          *      Being outputting the bytes.
 796          */
 797          
 798         do 
 799         {
 800                 struct sk_buff * skb;
 801                 int error;
 802                 char *data;
 803 
 804                 /*
 805                  *      Get the memory we require with some space left for alignment.
 806                  */
 807 
 808                 skb = sock_alloc_send_skb(sk, fraglen+15, 0, noblock, &error);
 809                 if (skb == NULL)
 810                 {
 811                         ip_statistics.IpOutDiscards++;
 812                         if(nfrags>1)
 813                                 ip_statistics.IpFragCreates++;                  
 814                         dev_unlock_list();
 815                         return(error);
 816                 }
 817                 
 818                 /*
 819                  *      Fill in the control structures
 820                  */
 821                  
 822                 skb->dev = dev;
 823                 skb->protocol = htons(ETH_P_IP);
 824                 skb->when = jiffies;
 825                 skb->free = 1; /* dubious, this one */
 826                 skb->sk = sk;
 827                 skb->arp = 0;
 828                 skb->saddr = saddr;
 829                 skb->raddr = raddr;
 830                 skb_reserve(skb,(dev->hard_header_len+15)&~15);
 831                 data = skb_put(skb, fraglen-dev->hard_header_len);
 832 
 833                 /*
 834                  *      Save us ARP and stuff. In the optimal case we do no route lookup (route cache ok)
 835                  *      no ARP lookup (arp cache ok) and output. The cache checks are still too slow but
 836                  *      this can be fixed later. For gateway routes we ought to have a rt->.. header cache
 837                  *      pointer to speed header cache builds for identical targets.
 838                  */
 839                  
 840                 if (hh)
 841                 {
 842                         skb->arp=1;
 843                         memcpy(skb_push(skb,dev->hard_header_len),hh->hh_data,dev->hard_header_len);
 844                         if (!hh->hh_uptodate)
 845                         {
 846                                 skb->arp = 0;
 847 #if RT_CACHE_DEBUG >= 2
 848                                 printk("ip_build_xmit: hh miss %08x via %08x\n", rt->rt_dst, rt->rt_gateway);
 849 #endif                          
 850                         }
 851                 }
 852                 else if (dev->hard_header)
 853                 {
 854                         if(dev->hard_header(skb, dev, ETH_P_IP, 
 855                                                 NULL, NULL, 0)>0)
 856                                 skb->arp=1;
 857                 }
 858                 
 859                 /*
 860                  *      Find where to start putting bytes.
 861                  */
 862                  
 863                 skb->ip_hdr = iph = (struct iphdr *)data;
 864 
 865                 /*
 866                  *      Only write IP header onto non-raw packets 
 867                  */
 868                  
 869                 if(!sk->ip_hdrincl) 
 870                 {
 871 
 872                         iph->version = 4;
 873                         iph->ihl = 5; /* ugh */
 874                         if (opt) {
 875                                 iph->ihl += opt->optlen>>2;
 876                                 ip_options_build(skb, opt,
 877                                                  true_daddr, dev->pa_addr, offset);
 878                         }
 879                         iph->tos = sk->ip_tos;
 880                         iph->tot_len = htons(fraglen - fragheaderlen + iph->ihl*4);
 881                         iph->id = id;
 882                         iph->frag_off = htons(offset>>3);
 883                         iph->frag_off |= mf;
 884 #ifdef CONFIG_IP_MULTICAST
 885                         if (MULTICAST(daddr))
 886                                 iph->ttl = sk->ip_mc_ttl;
 887                         else
 888 #endif
 889                                 iph->ttl = sk->ip_ttl;
 890                         iph->protocol = type;
 891                         iph->check = 0;
 892                         iph->saddr = saddr;
 893                         iph->daddr = daddr;
 894                         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
 895                         data += iph->ihl*4;
 896                         
 897                         /*
 898                          *      Any further fragments will have MF set.
 899                          */
 900                          
 901                         mf = htons(IP_MF);
 902                 }
 903                 
 904                 /*
 905                  *      User data callback
 906                  */
 907 
 908                 getfrag(frag, saddr, data, offset, fraglen-fragheaderlen);
 909                 
 910                 /*
 911                  *      Account for the fragment.
 912                  */
 913                  
 914 #ifdef CONFIG_FIREWALL
 915                 if(!offset && call_out_firewall(PF_INET, skb, iph) < FW_ACCEPT)
 916                 {
 917                         kfree_skb(skb, FREE_WRITE);
 918                         dev_unlock_list();
 919                         return -EPERM;
 920                 }
 921 #endif          
 922 #ifdef CONFIG_IP_ACCT
 923                 if(!offset)
 924                         ip_fw_chk(iph, dev, ip_acct_chain, IP_FW_F_ACCEPT, 1);
 925 #endif  
 926                 offset -= (maxfraglen-fragheaderlen);
 927                 fraglen = maxfraglen;
 928 
 929 #ifdef CONFIG_IP_MULTICAST
 930 
 931                 /*
 932                  *      Multicasts are looped back for other local users
 933                  */
 934          
 935                 if (MULTICAST(daddr) && !(dev->flags&IFF_LOOPBACK)) 
 936                 {
 937                         /*
 938                          *      Loop back any frames. The check for IGMP_ALL_HOSTS is because
 939                          *      you are always magically a member of this group.
 940                          *
 941                          *      Always loop back all host messages when running as a multicast router.
 942                          */
 943                          
 944                         if(sk==NULL || sk->ip_mc_loop)
 945                         {
 946                                 if(skb->daddr==IGMP_ALL_HOSTS || (dev->flags&IFF_ALLMULTI))
 947                                         ip_loopback(dev,skb);
 948                                 else 
 949                                 {
 950                                         struct ip_mc_list *imc=dev->ip_mc_list;
 951                                         while(imc!=NULL) 
 952                                         {
 953                                                 if(imc->multiaddr==daddr) 
 954                                                 {
 955                                                         ip_loopback(dev,skb);
 956                                                         break;
 957                                                 }
 958                                                 imc=imc->next;
 959                                         }
 960                                 }
 961                         }
 962 
 963                         /*
 964                          *      Multicasts with ttl 0 must not go beyond the host. Fixme: avoid the
 965                          *      extra clone.
 966                          */
 967 
 968                         if(skb->ip_hdr->ttl==0)
 969                                 kfree_skb(skb, FREE_READ);
 970                 }
 971 #endif
 972 
 973                 nfrags++;
 974                 
 975                 /*
 976                  *      BSD loops broadcasts
 977                  */
 978                  
 979                 if((dev->flags&IFF_BROADCAST) && (daddr==0xFFFFFFFF || daddr==dev->pa_brdaddr) && !(dev->flags&IFF_LOOPBACK))
 980                         ip_loopback(dev,skb);
 981 
 982                 /*
 983                  *      Now queue the bytes into the device.
 984                  */
 985                  
 986                 if (dev->flags & IFF_UP) 
 987                 {
 988                         dev_queue_xmit(skb, dev, sk->priority);
 989                 } 
 990                 else 
 991                 {
 992                         /*
 993                          *      Whoops... 
 994                          */
 995                          
 996                         ip_statistics.IpOutDiscards++;
 997                         if(nfrags>1)
 998                                 ip_statistics.IpFragCreates+=nfrags;
 999                         kfree_skb(skb, FREE_WRITE);
1000                         dev_unlock_list();
1001                         /*
1002                          *      BSD behaviour.
1003                          */
1004                         if(sk!=NULL)
1005                                 sk->err=ENETDOWN;
1006                         return(0); /* lose rest of fragments */
1007                 }
1008         } 
1009         while (offset >= 0);
1010         if(nfrags>1)
1011                 ip_statistics.IpFragCreates+=nfrags;
1012         dev_unlock_list();
1013         return(0);
1014 }
1015     
1016 
1017 /*
1018  *      IP protocol layer initialiser
1019  */
1020 
1021 static struct packet_type ip_packet_type =
1022 {
1023         0,      /* MUTTER ntohs(ETH_P_IP),*/
1024         NULL,   /* All devices */
1025         ip_rcv,
1026         NULL,
1027         NULL,
1028 };
1029 
1030 #ifdef CONFIG_RTNETLINK
1031 
1032 /*
1033  *      Netlink hooks for IP
1034  */
1035  
1036 void ip_netlink_msg(unsigned long msg, __u32 daddr, __u32 gw, __u32 mask, short flags, short metric, char *name)
     /* [previous][next][first][last][top][bottom][index][help] */
1037 {
1038         struct sk_buff *skb=alloc_skb(sizeof(struct netlink_rtinfo), GFP_ATOMIC);
1039         struct netlink_rtinfo *nrt;
1040         struct sockaddr_in *s;
1041         if(skb==NULL)
1042                 return;
1043         skb->free=1;
1044         nrt=(struct netlink_rtinfo *)skb_put(skb, sizeof(struct netlink_rtinfo));
1045         nrt->rtmsg_type=msg;
1046         s=(struct sockaddr_in *)&nrt->rtmsg_dst;
1047         s->sin_family=AF_INET;
1048         s->sin_addr.s_addr=daddr;
1049         s=(struct sockaddr_in *)&nrt->rtmsg_gateway;
1050         s->sin_family=AF_INET;
1051         s->sin_addr.s_addr=gw;
1052         s=(struct sockaddr_in *)&nrt->rtmsg_genmask;
1053         s->sin_family=AF_INET;
1054         s->sin_addr.s_addr=mask;
1055         nrt->rtmsg_flags=flags;
1056         nrt->rtmsg_metric=metric;
1057         strcpy(nrt->rtmsg_device,name);
1058         netlink_post(NETLINK_ROUTE, skb);
1059 }       
1060 
1061 #endif
1062 
1063 /*
1064  *      Device notifier
1065  */
1066  
1067 static int ip_rt_event(struct notifier_block *this, unsigned long event, void *ptr)
     /* [previous][next][first][last][top][bottom][index][help] */
1068 {
1069         struct device *dev=ptr;
1070         if(event==NETDEV_DOWN)
1071         {
1072                 ip_netlink_msg(RTMSG_DELDEVICE, 0,0,0,0,0,dev->name);
1073                 ip_rt_flush(dev);
1074         }
1075 /*
1076  *      Join the intial group if multicast.
1077  */             
1078         if(event==NETDEV_UP)
1079         {
1080 #ifdef CONFIG_IP_MULTICAST      
1081                 ip_mc_allhost(dev);
1082 #endif          
1083                 ip_netlink_msg(RTMSG_NEWDEVICE, 0,0,0,0,0,dev->name);
1084         }
1085         return NOTIFY_DONE;
1086 }
1087 
1088 struct notifier_block ip_rt_notifier={
1089         ip_rt_event,
1090         NULL,
1091         0
1092 };
1093 
1094 /*
1095  *      IP registers the packet type and then calls the subprotocol initialisers
1096  */
1097 
1098 void ip_init(void)
     /* [previous][next][first][last][top][bottom][index][help] */
1099 {
1100         ip_packet_type.type=htons(ETH_P_IP);
1101         dev_add_pack(&ip_packet_type);
1102 
1103         /* So we flush routes when a device is downed */        
1104         register_netdevice_notifier(&ip_rt_notifier);
1105 
1106 /*      ip_raw_init();
1107         ip_packet_init();
1108         ip_tcp_init();
1109         ip_udp_init();*/
1110 
1111 #ifdef CONFIG_IP_MULTICAST
1112         proc_net_register(&(struct proc_dir_entry) {
1113                 PROC_NET_IGMP, 4, "igmp",
1114                 S_IFREG | S_IRUGO, 1, 0, 0,
1115                 0, &proc_net_inode_operations,
1116                 ip_mc_procinfo
1117         });
1118 #endif
1119 }
1120 

/* [previous][next][first][last][top][bottom][index][help] */