git.oblomov.eu Git - linux-2.6/blob - net/ipv4/ip_output.c

   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:     $Id: ip_output.c,v 1.100 2002/02/01 22:01:03 davem Exp $
   9  *
  10  * Authors:     Ross Biro
  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  *              Hirokazu Takahashi, <taka@valinux.co.jp>
  19  *
  20  *      See ip_input.c for original log
  21  *
  22  *      Fixes:
  23  *              Alan Cox        :       Missing nonblock feature in ip_build_xmit.
  24  *              Mike Kilburn    :       htons() missing in ip_build_xmit.
  25  *              Bradford Johnson:       Fix faulty handling of some frames when
  26  *                                      no route is found.
  27  *              Alexander Demenshin:    Missing sk/skb free in ip_queue_xmit
  28  *                                      (in case if packet not accepted by
  29  *                                      output firewall rules)
  30  *              Mike McLagan    :       Routing by source
  31  *              Alexey Kuznetsov:       use new route cache
  32  *              Andi Kleen:             Fix broken PMTU recovery and remove
  33  *                                      some redundant tests.
  34  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
  35  *              Andi Kleen      :       Replace ip_reply with ip_send_reply.
  36  *              Andi Kleen      :       Split fast and slow ip_build_xmit path
  37  *                                      for decreased register pressure on x86
  38  *                                      and more readibility.
  39  *              Marc Boucher    :       When call_out_firewall returns FW_QUEUE,
  40  *                                      silently drop skb instead of failing with -EPERM.
  41  *              Detlev Wengorz  :       Copy protocol for fragments.
  42  *              Hirokazu Takahashi:     HW checksumming for outgoing UDP
  43  *                                      datagrams.
  44  *              Hirokazu Takahashi:     sendfile() on UDP works now.
  45  */
  46
  47 #include <asm/uaccess.h>
  48 #include <asm/system.h>
  49 #include <linux/module.h>
  50 #include <linux/types.h>
  51 #include <linux/kernel.h>
  52 #include <linux/sched.h>
  53 #include <linux/mm.h>
  54 #include <linux/string.h>
  55 #include <linux/errno.h>
  56
  57 #include <linux/socket.h>
  58 #include <linux/sockios.h>
  59 #include <linux/in.h>
  60 #include <linux/inet.h>
  61 #include <linux/netdevice.h>
  62 #include <linux/etherdevice.h>
  63 #include <linux/proc_fs.h>
  64 #include <linux/stat.h>
  65 #include <linux/init.h>
  66
  67 #include <net/snmp.h>
  68 #include <net/ip.h>
  69 #include <net/protocol.h>
  70 #include <net/route.h>
  71 #include <net/xfrm.h>
  72 #include <linux/skbuff.h>
  73 #include <net/sock.h>
  74 #include <net/arp.h>
  75 #include <net/icmp.h>
  76 #include <net/checksum.h>
  77 #include <net/inetpeer.h>
  78 #include <net/checksum.h>
  79 #include <linux/igmp.h>
  80 #include <linux/netfilter_ipv4.h>
  81 #include <linux/netfilter_bridge.h>
  82 #include <linux/mroute.h>
  83 #include <linux/netlink.h>
  84 #include <linux/tcp.h>
  85
  86 int sysctl_ip_default_ttl = IPDEFTTL;
  87
  88 /* Generate a checksum for an outgoing IP datagram. */
  89 __inline__ void ip_send_check(struct iphdr *iph)
  90 {
  91         iph->check = 0;
  92         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  93 }
  94
  95 /* dev_loopback_xmit for use with netfilter. */
  96 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
  97 {
  98         newskb->mac.raw = newskb->data;
  99         __skb_pull(newskb, newskb->nh.raw - newskb->data);
 100         newskb->pkt_type = PACKET_LOOPBACK;
 101         newskb->ip_summed = CHECKSUM_UNNECESSARY;
 102         BUG_TRAP(newskb->dst);
 103         netif_rx(newskb);
 104         return 0;
 105 }
 106
 107 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 108 {
 109         int ttl = inet->uc_ttl;
 110
 111         if (ttl < 0)
 112                 ttl = dst_metric(dst, RTAX_HOPLIMIT);
 113         return ttl;
 114 }
 115
 116 /*
 117  *              Add an ip header to a skbuff and send it out.
 118  *
 119  */
 120 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 121                           u32 saddr, u32 daddr, struct ip_options *opt)
 122 {
 123         struct inet_sock *inet = inet_sk(sk);
 124         struct rtable *rt = (struct rtable *)skb->dst;
 125         struct iphdr *iph;
 126
 127         /* Build the IP header. */
 128         if (opt)
 129                 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr) + opt->optlen);
 130         else
 131                 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr));
 132
 133         iph->version  = 4;
 134         iph->ihl      = 5;
 135         iph->tos      = inet->tos;
 136         if (ip_dont_fragment(sk, &rt->u.dst))
 137                 iph->frag_off = htons(IP_DF);
 138         else
 139                 iph->frag_off = 0;
 140         iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
 141         iph->daddr    = rt->rt_dst;
 142         iph->saddr    = rt->rt_src;
 143         iph->protocol = sk->sk_protocol;
 144         iph->tot_len  = htons(skb->len);
 145         ip_select_ident(iph, &rt->u.dst, sk);
 146         skb->nh.iph   = iph;
 147
 148         if (opt && opt->optlen) {
 149                 iph->ihl += opt->optlen>>2;
 150                 ip_options_build(skb, opt, daddr, rt, 0);
 151         }
 152         ip_send_check(iph);
 153
 154         skb->priority = sk->sk_priority;
 155
 156         /* Send it out. */
 157         return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
 158                        dst_output);
 159 }
 160
 161 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 162
 163 static inline int ip_finish_output2(struct sk_buff *skb)
 164 {
 165         struct dst_entry *dst = skb->dst;
 166         struct hh_cache *hh = dst->hh;
 167         struct net_device *dev = dst->dev;
 168         int hh_len = LL_RESERVED_SPACE(dev);
 169
 170         /* Be paranoid, rather than too clever. */
 171         if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) {
 172                 struct sk_buff *skb2;
 173
 174                 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 175                 if (skb2 == NULL) {
 176                         kfree_skb(skb);
 177                         return -ENOMEM;
 178                 }
 179                 if (skb->sk)
 180                         skb_set_owner_w(skb2, skb->sk);
 181                 kfree_skb(skb);
 182                 skb = skb2;
 183         }
 184
 185         if (hh) {
 186                 int hh_alen;
 187
 188                 read_lock_bh(&hh->hh_lock);
 189                 hh_alen = HH_DATA_ALIGN(hh->hh_len);
 190                 memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
 191                 read_unlock_bh(&hh->hh_lock);
 192                 skb_push(skb, hh->hh_len);
 193                 return hh->hh_output(skb);
 194         } else if (dst->neighbour)
 195                 return dst->neighbour->output(skb);
 196
 197         if (net_ratelimit())
 198                 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
 199         kfree_skb(skb);
 200         return -EINVAL;
 201 }
 202
 203 static inline int ip_finish_output(struct sk_buff *skb)
 204 {
 205 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 206         /* Policy lookup after SNAT yielded a new policy */
 207         if (skb->dst->xfrm != NULL) {
 208                 IPCB(skb)->flags |= IPSKB_REROUTED;
 209                 return dst_output(skb);
 210         }
 211 #endif
 212         if (skb->len > dst_mtu(skb->dst) && !skb_is_gso(skb))
 213                 return ip_fragment(skb, ip_finish_output2);
 214         else
 215                 return ip_finish_output2(skb);
 216 }
 217
 218 int ip_mc_output(struct sk_buff *skb)
 219 {
 220         struct sock *sk = skb->sk;
 221         struct rtable *rt = (struct rtable*)skb->dst;
 222         struct net_device *dev = rt->u.dst.dev;
 223
 224         /*
 225          *      If the indicated interface is up and running, send the packet.
 226          */
 227         IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
 228
 229         skb->dev = dev;
 230         skb->protocol = htons(ETH_P_IP);
 231
 232         /*
 233          *      Multicasts are looped back for other local users
 234          */
 235
 236         if (rt->rt_flags&RTCF_MULTICAST) {
 237                 if ((!sk || inet_sk(sk)->mc_loop)
 238 #ifdef CONFIG_IP_MROUTE
 239                 /* Small optimization: do not loopback not local frames,
 240                    which returned after forwarding; they will be  dropped
 241                    by ip_mr_input in any case.
 242                    Note, that local frames are looped back to be delivered
 243                    to local recipients.
 244
 245                    This check is duplicated in ip_mr_input at the moment.
 246                  */
 247                     && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED))
 248 #endif
 249                 ) {
 250                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 251                         if (newskb)
 252                                 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
 253                                         newskb->dev,
 254                                         ip_dev_loopback_xmit);
 255                 }
 256
 257                 /* Multicasts with ttl 0 must not go beyond the host */
 258
 259                 if (skb->nh.iph->ttl == 0) {
 260                         kfree_skb(skb);
 261                         return 0;
 262                 }
 263         }
 264
 265         if (rt->rt_flags&RTCF_BROADCAST) {
 266                 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 267                 if (newskb)
 268                         NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
 269                                 newskb->dev, ip_dev_loopback_xmit);
 270         }
 271
 272         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dev,
 273                             ip_finish_output,
 274                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 275 }
 276
 277 int ip_output(struct sk_buff *skb)
 278 {
 279         struct net_device *dev = skb->dst->dev;
 280
 281         IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
 282
 283         skb->dev = dev;
 284         skb->protocol = htons(ETH_P_IP);
 285
 286         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
 287                             ip_finish_output,
 288                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 289 }
 290
 291 int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
 292 {
 293         struct sock *sk = skb->sk;
 294         struct inet_sock *inet = inet_sk(sk);
 295         struct ip_options *opt = inet->opt;
 296         struct rtable *rt;
 297         struct iphdr *iph;
 298
 299         /* Skip all of this if the packet is already routed,
 300          * f.e. by something like SCTP.
 301          */
 302         rt = (struct rtable *) skb->dst;
 303         if (rt != NULL)
 304                 goto packet_routed;
 305
 306         /* Make sure we can route this packet. */
 307         rt = (struct rtable *)__sk_dst_check(sk, 0);
 308         if (rt == NULL) {
 309                 u32 daddr;
 310
 311                 /* Use correct destination address if we have options. */
 312                 daddr = inet->daddr;
 313                 if(opt && opt->srr)
 314                         daddr = opt->faddr;
 315
 316                 {
 317                         struct flowi fl = { .oif = sk->sk_bound_dev_if,
 318                                             .nl_u = { .ip4_u =
 319                                                       { .daddr = daddr,
 320                                                         .saddr = inet->saddr,
 321                                                         .tos = RT_CONN_FLAGS(sk) } },
 322                                             .proto = sk->sk_protocol,
 323                                             .uli_u = { .ports =
 324                                                        { .sport = inet->sport,
 325                                                          .dport = inet->dport } } };
 326
 327                         /* If this fails, retransmit mechanism of transport layer will
 328                          * keep trying until route appears or the connection times
 329                          * itself out.
 330                          */
 331                         if (ip_route_output_flow(&rt, &fl, sk, 0))
 332                                 goto no_route;
 333                 }
 334                 sk_setup_caps(sk, &rt->u.dst);
 335         }
 336         skb->dst = dst_clone(&rt->u.dst);
 337
 338 packet_routed:
 339         if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
 340                 goto no_route;
 341
 342         /* OK, we know where to send it, allocate and build IP header. */
 343         iph = (struct iphdr *) skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
 344         *((__u16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 345         iph->tot_len = htons(skb->len);
 346         if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
 347                 iph->frag_off = htons(IP_DF);
 348         else
 349                 iph->frag_off = 0;
 350         iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
 351         iph->protocol = sk->sk_protocol;
 352         iph->saddr    = rt->rt_src;
 353         iph->daddr    = rt->rt_dst;
 354         skb->nh.iph   = iph;
 355         /* Transport layer set skb->h.foo itself. */
 356
 357         if (opt && opt->optlen) {
 358                 iph->ihl += opt->optlen >> 2;
 359                 ip_options_build(skb, opt, inet->daddr, rt, 0);
 360         }
 361
 362         ip_select_ident_more(iph, &rt->u.dst, sk,
 363                              (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 364
 365         /* Add an IP checksum. */
 366         ip_send_check(iph);
 367
 368         skb->priority = sk->sk_priority;
 369
 370         return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
 371                        dst_output);
 372
 373 no_route:
 374         IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
 375         kfree_skb(skb);
 376         return -EHOSTUNREACH;
 377 }
 378
 379
 380 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 381 {
 382         to->pkt_type = from->pkt_type;
 383         to->priority = from->priority;
 384         to->protocol = from->protocol;
 385         dst_release(to->dst);
 386         to->dst = dst_clone(from->dst);
 387         to->dev = from->dev;
 388
 389         /* Copy the flags to each fragment. */
 390         IPCB(to)->flags = IPCB(from)->flags;
 391
 392 #ifdef CONFIG_NET_SCHED
 393         to->tc_index = from->tc_index;
 394 #endif
 395 #ifdef CONFIG_NETFILTER
 396         to->nfmark = from->nfmark;
 397         /* Connection association is same as pre-frag packet */
 398         nf_conntrack_put(to->nfct);
 399         to->nfct = from->nfct;
 400         nf_conntrack_get(to->nfct);
 401         to->nfctinfo = from->nfctinfo;
 402 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 403         to->ipvs_property = from->ipvs_property;
 404 #endif
 405 #ifdef CONFIG_BRIDGE_NETFILTER
 406         nf_bridge_put(to->nf_bridge);
 407         to->nf_bridge = from->nf_bridge;
 408         nf_bridge_get(to->nf_bridge);
 409 #endif
 410 #endif
 411         skb_copy_secmark(to, from);
 412 }
 413
 414 /*
 415  *      This IP datagram is too large to be sent in one piece.  Break it up into
 416  *      smaller pieces (each of size equal to IP header plus
 417  *      a block of the data of the original IP data part) that will yet fit in a
 418  *      single device frame, and queue such a frame for sending.
 419  */
 420
 421 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
 422 {
 423         struct iphdr *iph;
 424         int raw = 0;
 425         int ptr;
 426         struct net_device *dev;
 427         struct sk_buff *skb2;
 428         unsigned int mtu, hlen, left, len, ll_rs;
 429         int offset;
 430         __be16 not_last_frag;
 431         struct rtable *rt = (struct rtable*)skb->dst;
 432         int err = 0;
 433
 434         dev = rt->u.dst.dev;
 435
 436         /*
 437          *      Point into the IP datagram header.
 438          */
 439
 440         iph = skb->nh.iph;
 441
 442         if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
 443                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 444                           htonl(dst_mtu(&rt->u.dst)));
 445                 kfree_skb(skb);
 446                 return -EMSGSIZE;
 447         }
 448
 449         /*
 450          *      Setup starting values.
 451          */
 452
 453         hlen = iph->ihl * 4;
 454         mtu = dst_mtu(&rt->u.dst) - hlen;       /* Size of data space */
 455         IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 456
 457         /* When frag_list is given, use it. First, check its validity:
 458          * some transformers could create wrong frag_list or break existing
 459          * one, it is not prohibited. In this case fall back to copying.
 460          *
 461          * LATER: this step can be merged to real generation of fragments,
 462          * we can switch to copy when see the first bad fragment.
 463          */
 464         if (skb_shinfo(skb)->frag_list) {
 465                 struct sk_buff *frag;
 466                 int first_len = skb_pagelen(skb);
 467
 468                 if (first_len - hlen > mtu ||
 469                     ((first_len - hlen) & 7) ||
 470                     (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
 471                     skb_cloned(skb))
 472                         goto slow_path;
 473
 474                 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
 475                         /* Correct geometry. */
 476                         if (frag->len > mtu ||
 477                             ((frag->len & 7) && frag->next) ||
 478                             skb_headroom(frag) < hlen)
 479                             goto slow_path;
 480
 481                         /* Partially cloned skb? */
 482                         if (skb_shared(frag))
 483                                 goto slow_path;
 484
 485                         BUG_ON(frag->sk);
 486                         if (skb->sk) {
 487                                 sock_hold(skb->sk);
 488                                 frag->sk = skb->sk;
 489                                 frag->destructor = sock_wfree;
 490                                 skb->truesize -= frag->truesize;
 491                         }
 492                 }
 493
 494                 /* Everything is OK. Generate! */
 495
 496                 err = 0;
 497                 offset = 0;
 498                 frag = skb_shinfo(skb)->frag_list;
 499                 skb_shinfo(skb)->frag_list = NULL;
 500                 skb->data_len = first_len - skb_headlen(skb);
 501                 skb->len = first_len;
 502                 iph->tot_len = htons(first_len);
 503                 iph->frag_off = htons(IP_MF);
 504                 ip_send_check(iph);
 505
 506                 for (;;) {
 507                         /* Prepare header of the next frame,
 508                          * before previous one went down. */
 509                         if (frag) {
 510                                 frag->ip_summed = CHECKSUM_NONE;
 511                                 frag->h.raw = frag->data;
 512                                 frag->nh.raw = __skb_push(frag, hlen);
 513                                 memcpy(frag->nh.raw, iph, hlen);
 514                                 iph = frag->nh.iph;
 515                                 iph->tot_len = htons(frag->len);
 516                                 ip_copy_metadata(frag, skb);
 517                                 if (offset == 0)
 518                                         ip_options_fragment(frag);
 519                                 offset += skb->len - hlen;
 520                                 iph->frag_off = htons(offset>>3);
 521                                 if (frag->next != NULL)
 522                                         iph->frag_off |= htons(IP_MF);
 523                                 /* Ready, complete checksum */
 524                                 ip_send_check(iph);
 525                         }
 526
 527                         err = output(skb);
 528
 529                         if (!err)
 530                                 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
 531                         if (err || !frag)
 532                                 break;
 533
 534                         skb = frag;
 535                         frag = skb->next;
 536                         skb->next = NULL;
 537                 }
 538
 539                 if (err == 0) {
 540                         IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
 541                         return 0;
 542                 }
 543
 544                 while (frag) {
 545                         skb = frag->next;
 546                         kfree_skb(frag);
 547                         frag = skb;
 548                 }
 549                 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
 550                 return err;
 551         }
 552
 553 slow_path:
 554         left = skb->len - hlen;         /* Space per frame */
 555         ptr = raw + hlen;               /* Where to start from */
 556
 557 #ifdef CONFIG_BRIDGE_NETFILTER
 558         /* for bridged IP traffic encapsulated inside f.e. a vlan header,
 559          * we need to make room for the encapsulating header */
 560         ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, nf_bridge_pad(skb));
 561         mtu -= nf_bridge_pad(skb);
 562 #else
 563         ll_rs = LL_RESERVED_SPACE(rt->u.dst.dev);
 564 #endif
 565         /*
 566          *      Fragment the datagram.
 567          */
 568
 569         offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 570         not_last_frag = iph->frag_off & htons(IP_MF);
 571
 572         /*
 573          *      Keep copying data until we run out.
 574          */
 575
 576         while(left > 0) {
 577                 len = left;
 578                 /* IF: it doesn't fit, use 'mtu' - the data space left */
 579                 if (len > mtu)
 580                         len = mtu;
 581                 /* IF: we are not sending upto and including the packet end
 582                    then align the next start on an eight byte boundary */
 583                 if (len < left) {
 584                         len &= ~7;
 585                 }
 586                 /*
 587                  *      Allocate buffer.
 588                  */
 589
 590                 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
 591                         NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
 592                         err = -ENOMEM;
 593                         goto fail;
 594                 }
 595
 596                 /*
 597                  *      Set up data on packet
 598                  */
 599
 600                 ip_copy_metadata(skb2, skb);
 601                 skb_reserve(skb2, ll_rs);
 602                 skb_put(skb2, len + hlen);
 603                 skb2->nh.raw = skb2->data;
 604                 skb2->h.raw = skb2->data + hlen;
 605
 606                 /*
 607                  *      Charge the memory for the fragment to any owner
 608                  *      it might possess
 609                  */
 610
 611                 if (skb->sk)
 612                         skb_set_owner_w(skb2, skb->sk);
 613
 614                 /*
 615                  *      Copy the packet header into the new buffer.
 616                  */
 617
 618                 memcpy(skb2->nh.raw, skb->data, hlen);
 619
 620                 /*
 621                  *      Copy a block of the IP datagram.
 622                  */
 623                 if (skb_copy_bits(skb, ptr, skb2->h.raw, len))
 624                         BUG();
 625                 left -= len;
 626
 627                 /*
 628                  *      Fill in the new header fields.
 629                  */
 630                 iph = skb2->nh.iph;
 631                 iph->frag_off = htons((offset >> 3));
 632
 633                 /* ANK: dirty, but effective trick. Upgrade options only if
 634                  * the segment to be fragmented was THE FIRST (otherwise,
 635                  * options are already fixed) and make it ONCE
 636                  * on the initial skb, so that all the following fragments
 637                  * will inherit fixed options.
 638                  */
 639                 if (offset == 0)
 640                         ip_options_fragment(skb);
 641
 642                 /*
 643                  *      Added AC : If we are fragmenting a fragment that's not the
 644                  *                 last fragment then keep MF on each bit
 645                  */
 646                 if (left > 0 || not_last_frag)
 647                         iph->frag_off |= htons(IP_MF);
 648                 ptr += len;
 649                 offset += len;
 650
 651                 /*
 652                  *      Put this fragment into the sending queue.
 653                  */
 654                 iph->tot_len = htons(len + hlen);
 655
 656                 ip_send_check(iph);
 657
 658                 err = output(skb2);
 659                 if (err)
 660                         goto fail;
 661
 662                 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
 663         }
 664         kfree_skb(skb);
 665         IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
 666         return err;
 667
 668 fail:
 669         kfree_skb(skb);
 670         IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
 671         return err;
 672 }
 673
 674 EXPORT_SYMBOL(ip_fragment);
 675
 676 int
 677 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
 678 {
 679         struct iovec *iov = from;
 680
 681         if (skb->ip_summed == CHECKSUM_HW) {
 682                 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
 683                         return -EFAULT;
 684         } else {
 685                 unsigned int csum = 0;
 686                 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
 687                         return -EFAULT;
 688                 skb->csum = csum_block_add(skb->csum, csum, odd);
 689         }
 690         return 0;
 691 }
 692
 693 static inline unsigned int
 694 csum_page(struct page *page, int offset, int copy)
 695 {
 696         char *kaddr;
 697         unsigned int csum;
 698         kaddr = kmap(page);
 699         csum = csum_partial(kaddr + offset, copy, 0);
 700         kunmap(page);
 701         return csum;
 702 }
 703
 704 static inline int ip_ufo_append_data(struct sock *sk,
 705                         int getfrag(void *from, char *to, int offset, int len,
 706                                int odd, struct sk_buff *skb),
 707                         void *from, int length, int hh_len, int fragheaderlen,
 708                         int transhdrlen, int mtu,unsigned int flags)
 709 {
 710         struct sk_buff *skb;
 711         int err;
 712
 713         /* There is support for UDP fragmentation offload by network
 714          * device, so create one single skb packet containing complete
 715          * udp datagram
 716          */
 717         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
 718                 skb = sock_alloc_send_skb(sk,
 719                         hh_len + fragheaderlen + transhdrlen + 20,
 720                         (flags & MSG_DONTWAIT), &err);
 721
 722                 if (skb == NULL)
 723                         return err;
 724
 725                 /* reserve space for Hardware header */
 726                 skb_reserve(skb, hh_len);
 727
 728                 /* create space for UDP/IP header */
 729                 skb_put(skb,fragheaderlen + transhdrlen);
 730
 731                 /* initialize network header pointer */
 732                 skb->nh.raw = skb->data;
 733
 734                 /* initialize protocol header pointer */
 735                 skb->h.raw = skb->data + fragheaderlen;
 736
 737                 skb->ip_summed = CHECKSUM_HW;
 738                 skb->csum = 0;
 739                 sk->sk_sndmsg_off = 0;
 740         }
 741
 742         err = skb_append_datato_frags(sk,skb, getfrag, from,
 743                                (length - transhdrlen));
 744         if (!err) {
 745                 /* specify the length of each IP datagram fragment*/
 746                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
 747                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 748                 __skb_queue_tail(&sk->sk_write_queue, skb);
 749
 750                 return 0;
 751         }
 752         /* There is not enough support do UFO ,
 753          * so follow normal path
 754          */
 755         kfree_skb(skb);
 756         return err;
 757 }
 758
 759 /*
 760  *      ip_append_data() and ip_append_page() can make one large IP datagram
 761  *      from many pieces of data. Each pieces will be holded on the socket
 762  *      until ip_push_pending_frames() is called. Each piece can be a page
 763  *      or non-page data.
 764  *
 765  *      Not only UDP, other transport protocols - e.g. raw sockets - can use
 766  *      this interface potentially.
 767  *
 768  *      LATER: length must be adjusted by pad at tail, when it is required.
 769  */
 770 int ip_append_data(struct sock *sk,
 771                    int getfrag(void *from, char *to, int offset, int len,
 772                                int odd, struct sk_buff *skb),
 773                    void *from, int length, int transhdrlen,
 774                    struct ipcm_cookie *ipc, struct rtable *rt,
 775                    unsigned int flags)
 776 {
 777         struct inet_sock *inet = inet_sk(sk);
 778         struct sk_buff *skb;
 779
 780         struct ip_options *opt = NULL;
 781         int hh_len;
 782         int exthdrlen;
 783         int mtu;
 784         int copy;
 785         int err;
 786         int offset = 0;
 787         unsigned int maxfraglen, fragheaderlen;
 788         int csummode = CHECKSUM_NONE;
 789
 790         if (flags&MSG_PROBE)
 791                 return 0;
 792
 793         if (skb_queue_empty(&sk->sk_write_queue)) {
 794                 /*
 795                  * setup for corking.
 796                  */
 797                 opt = ipc->opt;
 798                 if (opt) {
 799                         if (inet->cork.opt == NULL) {
 800                                 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
 801                                 if (unlikely(inet->cork.opt == NULL))
 802                                         return -ENOBUFS;
 803                         }
 804                         memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen);
 805                         inet->cork.flags |= IPCORK_OPT;
 806                         inet->cork.addr = ipc->addr;
 807                 }
 808                 dst_hold(&rt->u.dst);
 809                 inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path);
 810                 inet->cork.rt = rt;
 811                 inet->cork.length = 0;
 812                 sk->sk_sndmsg_page = NULL;
 813                 sk->sk_sndmsg_off = 0;
 814                 if ((exthdrlen = rt->u.dst.header_len) != 0) {
 815                         length += exthdrlen;
 816                         transhdrlen += exthdrlen;
 817                 }
 818         } else {
 819                 rt = inet->cork.rt;
 820                 if (inet->cork.flags & IPCORK_OPT)
 821                         opt = inet->cork.opt;
 822
 823                 transhdrlen = 0;
 824                 exthdrlen = 0;
 825                 mtu = inet->cork.fragsize;
 826         }
 827         hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
 828
 829         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 830         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 831
 832         if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
 833                 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen);
 834                 return -EMSGSIZE;
 835         }
 836
 837         /*
 838          * transhdrlen > 0 means that this is the first fragment and we wish
 839          * it won't be fragmented in the future.
 840          */
 841         if (transhdrlen &&
 842             length + fragheaderlen <= mtu &&
 843             rt->u.dst.dev->features & NETIF_F_ALL_CSUM &&
 844             !exthdrlen)
 845                 csummode = CHECKSUM_HW;
 846
 847         inet->cork.length += length;
 848         if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
 849                         (rt->u.dst.dev->features & NETIF_F_UFO)) {
 850
 851                 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len,
 852                                          fragheaderlen, transhdrlen, mtu,
 853                                          flags);
 854                 if (err)
 855                         goto error;
 856                 return 0;
 857         }
 858
 859         /* So, what's going on in the loop below?
 860          *
 861          * We use calculated fragment length to generate chained skb,
 862          * each of segments is IP fragment ready for sending to network after
 863          * adding appropriate IP header.
 864          */
 865
 866         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
 867                 goto alloc_new_skb;
 868
 869         while (length > 0) {
 870                 /* Check if the remaining data fits into current packet. */
 871                 copy = mtu - skb->len;
 872                 if (copy < length)
 873                         copy = maxfraglen - skb->len;
 874                 if (copy <= 0) {
 875                         char *data;
 876                         unsigned int datalen;
 877                         unsigned int fraglen;
 878                         unsigned int fraggap;
 879                         unsigned int alloclen;
 880                         struct sk_buff *skb_prev;
 881 alloc_new_skb:
 882                         skb_prev = skb;
 883                         if (skb_prev)
 884                                 fraggap = skb_prev->len - maxfraglen;
 885                         else
 886                                 fraggap = 0;
 887
 888                         /*
 889                          * If remaining data exceeds the mtu,
 890                          * we know we need more fragment(s).
 891                          */
 892                         datalen = length + fraggap;
 893                         if (datalen > mtu - fragheaderlen)
 894                                 datalen = maxfraglen - fragheaderlen;
 895                         fraglen = datalen + fragheaderlen;
 896
 897                         if ((flags & MSG_MORE) &&
 898                             !(rt->u.dst.dev->features&NETIF_F_SG))
 899                                 alloclen = mtu;
 900                         else
 901                                 alloclen = datalen + fragheaderlen;
 902
 903                         /* The last fragment gets additional space at tail.
 904                          * Note, with MSG_MORE we overallocate on fragments,
 905                          * because we have no idea what fragment will be
 906                          * the last.
 907                          */
 908                         if (datalen == length + fraggap)
 909                                 alloclen += rt->u.dst.trailer_len;
 910
 911                         if (transhdrlen) {
 912                                 skb = sock_alloc_send_skb(sk,
 913                                                 alloclen + hh_len + 15,
 914                                                 (flags & MSG_DONTWAIT), &err);
 915                         } else {
 916                                 skb = NULL;
 917                                 if (atomic_read(&sk->sk_wmem_alloc) <=
 918                                     2 * sk->sk_sndbuf)
 919                                         skb = sock_wmalloc(sk,
 920                                                            alloclen + hh_len + 15, 1,
 921                                                            sk->sk_allocation);
 922                                 if (unlikely(skb == NULL))
 923                                         err = -ENOBUFS;
 924                         }
 925                         if (skb == NULL)
 926                                 goto error;
 927
 928                         /*
 929                          *      Fill in the control structures
 930                          */
 931                         skb->ip_summed = csummode;
 932                         skb->csum = 0;
 933                         skb_reserve(skb, hh_len);
 934
 935                         /*
 936                          *      Find where to start putting bytes.
 937                          */
 938                         data = skb_put(skb, fraglen);
 939                         skb->nh.raw = data + exthdrlen;
 940                         data += fragheaderlen;
 941                         skb->h.raw = data + exthdrlen;
 942
 943                         if (fraggap) {
 944                                 skb->csum = skb_copy_and_csum_bits(
 945                                         skb_prev, maxfraglen,
 946                                         data + transhdrlen, fraggap, 0);
 947                                 skb_prev->csum = csum_sub(skb_prev->csum,
 948                                                           skb->csum);
 949                                 data += fraggap;
 950                                 skb_trim(skb_prev, maxfraglen);
 951                         }
 952
 953                         copy = datalen - transhdrlen - fraggap;
 954                         if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
 955                                 err = -EFAULT;
 956                                 kfree_skb(skb);
 957                                 goto error;
 958                         }
 959
 960                         offset += copy;
 961                         length -= datalen - fraggap;
 962                         transhdrlen = 0;
 963                         exthdrlen = 0;
 964                         csummode = CHECKSUM_NONE;
 965
 966                         /*
 967                          * Put the packet on the pending queue.
 968                          */
 969                         __skb_queue_tail(&sk->sk_write_queue, skb);
 970                         continue;
 971                 }
 972
 973                 if (copy > length)
 974                         copy = length;
 975
 976                 if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
 977                         unsigned int off;
 978
 979                         off = skb->len;
 980                         if (getfrag(from, skb_put(skb, copy),
 981                                         offset, copy, off, skb) < 0) {
 982                                 __skb_trim(skb, off);
 983                                 err = -EFAULT;
 984                                 goto error;
 985                         }
 986                 } else {
 987                         int i = skb_shinfo(skb)->nr_frags;
 988                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
 989                         struct page *page = sk->sk_sndmsg_page;
 990                         int off = sk->sk_sndmsg_off;
 991                         unsigned int left;
 992
 993                         if (page && (left = PAGE_SIZE - off) > 0) {
 994                                 if (copy >= left)
 995                                         copy = left;
 996                                 if (page != frag->page) {
 997                                         if (i == MAX_SKB_FRAGS) {
 998                                                 err = -EMSGSIZE;
 999                                                 goto error;
1000                                         }
1001                                         get_page(page);
1002                                         skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
1003                                         frag = &skb_shinfo(skb)->frags[i];
1004                                 }
1005                         } else if (i < MAX_SKB_FRAGS) {
1006                                 if (copy > PAGE_SIZE)
1007                                         copy = PAGE_SIZE;
1008                                 page = alloc_pages(sk->sk_allocation, 0);
1009                                 if (page == NULL)  {
1010                                         err = -ENOMEM;
1011                                         goto error;
1012                                 }
1013                                 sk->sk_sndmsg_page = page;
1014                                 sk->sk_sndmsg_off = 0;
1015
1016                                 skb_fill_page_desc(skb, i, page, 0, 0);
1017                                 frag = &skb_shinfo(skb)->frags[i];
1018                                 skb->truesize += PAGE_SIZE;
1019                                 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
1020                         } else {
1021                                 err = -EMSGSIZE;
1022                                 goto error;
1023                         }
1024                         if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1025                                 err = -EFAULT;
1026                                 goto error;
1027                         }
1028                         sk->sk_sndmsg_off += copy;
1029                         frag->size += copy;
1030                         skb->len += copy;
1031                         skb->data_len += copy;
1032                 }
1033                 offset += copy;
1034                 length -= copy;
1035         }
1036
1037         return 0;
1038
1039 error:
1040         inet->cork.length -= length;
1041         IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1042         return err;
1043 }
1044
1045 ssize_t ip_append_page(struct sock *sk, struct page *page,
1046                        int offset, size_t size, int flags)
1047 {
1048         struct inet_sock *inet = inet_sk(sk);
1049         struct sk_buff *skb;
1050         struct rtable *rt;
1051         struct ip_options *opt = NULL;
1052         int hh_len;
1053         int mtu;
1054         int len;
1055         int err;
1056         unsigned int maxfraglen, fragheaderlen, fraggap;
1057
1058         if (inet->hdrincl)
1059                 return -EPERM;
1060
1061         if (flags&MSG_PROBE)
1062                 return 0;
1063
1064         if (skb_queue_empty(&sk->sk_write_queue))
1065                 return -EINVAL;
1066
1067         rt = inet->cork.rt;
1068         if (inet->cork.flags & IPCORK_OPT)
1069                 opt = inet->cork.opt;
1070
1071         if (!(rt->u.dst.dev->features&NETIF_F_SG))
1072                 return -EOPNOTSUPP;
1073
1074         hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
1075         mtu = inet->cork.fragsize;
1076
1077         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1078         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1079
1080         if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
1081                 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu);
1082                 return -EMSGSIZE;
1083         }
1084
1085         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1086                 return -EINVAL;
1087
1088         inet->cork.length += size;
1089         if ((sk->sk_protocol == IPPROTO_UDP) &&
1090             (rt->u.dst.dev->features & NETIF_F_UFO)) {
1091                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1092                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1093         }
1094
1095
1096         while (size > 0) {
1097                 int i;
1098
1099                 if (skb_is_gso(skb))
1100                         len = size;
1101                 else {
1102
1103                         /* Check if the remaining data fits into current packet. */
1104                         len = mtu - skb->len;
1105                         if (len < size)
1106                                 len = maxfraglen - skb->len;
1107                 }
1108                 if (len <= 0) {
1109                         struct sk_buff *skb_prev;
1110                         char *data;
1111                         struct iphdr *iph;
1112                         int alloclen;
1113
1114                         skb_prev = skb;
1115                         fraggap = skb_prev->len - maxfraglen;
1116
1117                         alloclen = fragheaderlen + hh_len + fraggap + 15;
1118                         skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1119                         if (unlikely(!skb)) {
1120                                 err = -ENOBUFS;
1121                                 goto error;
1122                         }
1123
1124                         /*
1125                          *      Fill in the control structures
1126                          */
1127                         skb->ip_summed = CHECKSUM_NONE;
1128                         skb->csum = 0;
1129                         skb_reserve(skb, hh_len);
1130
1131                         /*
1132                          *      Find where to start putting bytes.
1133                          */
1134                         data = skb_put(skb, fragheaderlen + fraggap);
1135                         skb->nh.iph = iph = (struct iphdr *)data;
1136                         data += fragheaderlen;
1137                         skb->h.raw = data;
1138
1139                         if (fraggap) {
1140                                 skb->csum = skb_copy_and_csum_bits(
1141                                         skb_prev, maxfraglen,
1142                                         data, fraggap, 0);
1143                                 skb_prev->csum = csum_sub(skb_prev->csum,
1144                                                           skb->csum);
1145                                 skb_trim(skb_prev, maxfraglen);
1146                         }
1147
1148                         /*
1149                          * Put the packet on the pending queue.
1150                          */
1151                         __skb_queue_tail(&sk->sk_write_queue, skb);
1152                         continue;
1153                 }
1154
1155                 i = skb_shinfo(skb)->nr_frags;
1156                 if (len > size)
1157                         len = size;
1158                 if (skb_can_coalesce(skb, i, page, offset)) {
1159                         skb_shinfo(skb)->frags[i-1].size += len;
1160                 } else if (i < MAX_SKB_FRAGS) {
1161                         get_page(page);
1162                         skb_fill_page_desc(skb, i, page, offset, len);
1163                 } else {
1164                         err = -EMSGSIZE;
1165                         goto error;
1166                 }
1167
1168                 if (skb->ip_summed == CHECKSUM_NONE) {
1169                         unsigned int csum;
1170                         csum = csum_page(page, offset, len);
1171                         skb->csum = csum_block_add(skb->csum, csum, skb->len);
1172                 }
1173
1174                 skb->len += len;
1175                 skb->data_len += len;
1176                 offset += len;
1177                 size -= len;
1178         }
1179         return 0;
1180
1181 error:
1182         inet->cork.length -= size;
1183         IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1184         return err;
1185 }
1186
1187 /*
1188  *      Combined all pending IP fragments on the socket as one IP datagram
1189  *      and push them out.
1190  */
1191 int ip_push_pending_frames(struct sock *sk)
1192 {
1193         struct sk_buff *skb, *tmp_skb;
1194         struct sk_buff **tail_skb;
1195         struct inet_sock *inet = inet_sk(sk);
1196         struct ip_options *opt = NULL;
1197         struct rtable *rt = inet->cork.rt;
1198         struct iphdr *iph;
1199         __be16 df = 0;
1200         __u8 ttl;
1201         int err = 0;
1202
1203         if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1204                 goto out;
1205         tail_skb = &(skb_shinfo(skb)->frag_list);
1206
1207         /* move skb->data to ip header from ext header */
1208         if (skb->data < skb->nh.raw)
1209                 __skb_pull(skb, skb->nh.raw - skb->data);
1210         while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1211                 __skb_pull(tmp_skb, skb->h.raw - skb->nh.raw);
1212                 *tail_skb = tmp_skb;
1213                 tail_skb = &(tmp_skb->next);
1214                 skb->len += tmp_skb->len;
1215                 skb->data_len += tmp_skb->len;
1216                 skb->truesize += tmp_skb->truesize;
1217                 __sock_put(tmp_skb->sk);
1218                 tmp_skb->destructor = NULL;
1219                 tmp_skb->sk = NULL;
1220         }
1221
1222         /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1223          * to fragment the frame generated here. No matter, what transforms
1224          * how transforms change size of the packet, it will come out.
1225          */
1226         if (inet->pmtudisc != IP_PMTUDISC_DO)
1227                 skb->local_df = 1;
1228
1229         /* DF bit is set when we want to see DF on outgoing frames.
1230          * If local_df is set too, we still allow to fragment this frame
1231          * locally. */
1232         if (inet->pmtudisc == IP_PMTUDISC_DO ||
1233             (skb->len <= dst_mtu(&rt->u.dst) &&
1234              ip_dont_fragment(sk, &rt->u.dst)))
1235                 df = htons(IP_DF);
1236
1237         if (inet->cork.flags & IPCORK_OPT)
1238                 opt = inet->cork.opt;
1239
1240         if (rt->rt_type == RTN_MULTICAST)
1241                 ttl = inet->mc_ttl;
1242         else
1243                 ttl = ip_select_ttl(inet, &rt->u.dst);
1244
1245         iph = (struct iphdr *)skb->data;
1246         iph->version = 4;
1247         iph->ihl = 5;
1248         if (opt) {
1249                 iph->ihl += opt->optlen>>2;
1250                 ip_options_build(skb, opt, inet->cork.addr, rt, 0);
1251         }
1252         iph->tos = inet->tos;
1253         iph->tot_len = htons(skb->len);
1254         iph->frag_off = df;
1255         ip_select_ident(iph, &rt->u.dst, sk);
1256         iph->ttl = ttl;
1257         iph->protocol = sk->sk_protocol;
1258         iph->saddr = rt->rt_src;
1259         iph->daddr = rt->rt_dst;
1260         ip_send_check(iph);
1261
1262         skb->priority = sk->sk_priority;
1263         skb->dst = dst_clone(&rt->u.dst);
1264
1265         /* Netfilter gets whole the not fragmented skb. */
1266         err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL,
1267                       skb->dst->dev, dst_output);
1268         if (err) {
1269                 if (err > 0)
1270                         err = inet->recverr ? net_xmit_errno(err) : 0;
1271                 if (err)
1272                         goto error;
1273         }
1274
1275 out:
1276         inet->cork.flags &= ~IPCORK_OPT;
1277         kfree(inet->cork.opt);
1278         inet->cork.opt = NULL;
1279         if (inet->cork.rt) {
1280                 ip_rt_put(inet->cork.rt);
1281                 inet->cork.rt = NULL;
1282         }
1283         return err;
1284
1285 error:
1286         IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1287         goto out;
1288 }
1289
1290 /*
1291  *      Throw away all pending data on the socket.
1292  */
1293 void ip_flush_pending_frames(struct sock *sk)
1294 {
1295         struct inet_sock *inet = inet_sk(sk);
1296         struct sk_buff *skb;
1297
1298         while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
1299                 kfree_skb(skb);
1300
1301         inet->cork.flags &= ~IPCORK_OPT;
1302         kfree(inet->cork.opt);
1303         inet->cork.opt = NULL;
1304         if (inet->cork.rt) {
1305                 ip_rt_put(inet->cork.rt);
1306                 inet->cork.rt = NULL;
1307         }
1308 }
1309
1310
1311 /*
1312  *      Fetch data from kernel space and fill in checksum if needed.
1313  */
1314 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1315                               int len, int odd, struct sk_buff *skb)
1316 {
1317         unsigned int csum;
1318
1319         csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1320         skb->csum = csum_block_add(skb->csum, csum, odd);
1321         return 0;
1322 }
1323
1324 /*
1325  *      Generic function to send a packet as reply to another packet.
1326  *      Used to send TCP resets so far. ICMP should use this function too.
1327  *
1328  *      Should run single threaded per socket because it uses the sock
1329  *      structure to pass arguments.
1330  *
1331  *      LATER: switch from ip_build_xmit to ip_append_*
1332  */
1333 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
1334                    unsigned int len)
1335 {
1336         struct inet_sock *inet = inet_sk(sk);
1337         struct {
1338                 struct ip_options       opt;
1339                 char                    data[40];
1340         } replyopts;
1341         struct ipcm_cookie ipc;
1342         u32 daddr;
1343         struct rtable *rt = (struct rtable*)skb->dst;
1344
1345         if (ip_options_echo(&replyopts.opt, skb))
1346                 return;
1347
1348         daddr = ipc.addr = rt->rt_src;
1349         ipc.opt = NULL;
1350
1351         if (replyopts.opt.optlen) {
1352                 ipc.opt = &replyopts.opt;
1353
1354                 if (ipc.opt->srr)
1355                         daddr = replyopts.opt.faddr;
1356         }
1357
1358         {
1359                 struct flowi fl = { .nl_u = { .ip4_u =
1360                                               { .daddr = daddr,
1361                                                 .saddr = rt->rt_spec_dst,
1362                                                 .tos = RT_TOS(skb->nh.iph->tos) } },
1363                                     /* Not quite clean, but right. */
1364                                     .uli_u = { .ports =
1365                                                { .sport = skb->h.th->dest,
1366                                                  .dport = skb->h.th->source } },
1367                                     .proto = sk->sk_protocol };
1368                 if (ip_route_output_key(&rt, &fl))
1369                         return;
1370         }
1371
1372         /* And let IP do all the hard work.
1373
1374            This chunk is not reenterable, hence spinlock.
1375            Note that it uses the fact, that this function is called
1376            with locally disabled BH and that sk cannot be already spinlocked.
1377          */
1378         bh_lock_sock(sk);
1379         inet->tos = skb->nh.iph->tos;
1380         sk->sk_priority = skb->priority;
1381         sk->sk_protocol = skb->nh.iph->protocol;
1382         ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1383                        &ipc, rt, MSG_DONTWAIT);
1384         if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1385                 if (arg->csumoffset >= 0)
1386                         *((u16 *)skb->h.raw + arg->csumoffset) = csum_fold(csum_add(skb->csum, arg->csum));
1387                 skb->ip_summed = CHECKSUM_NONE;
1388                 ip_push_pending_frames(sk);
1389         }
1390
1391         bh_unlock_sock(sk);
1392
1393         ip_rt_put(rt);
1394 }
1395
1396 void __init ip_init(void)
1397 {
1398         ip_rt_init();
1399         inet_initpeers();
1400
1401 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1402         igmp_mc_proc_init();
1403 #endif
1404 }
1405
1406 EXPORT_SYMBOL(ip_generic_getfrag);
1407 EXPORT_SYMBOL(ip_queue_xmit);
1408 EXPORT_SYMBOL(ip_send_check);