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 #include <linux/config.h>
  57
  58 #include <linux/socket.h>
  59 #include <linux/sockios.h>
  60 #include <linux/in.h>
  61 #include <linux/inet.h>
  62 #include <linux/netdevice.h>
  63 #include <linux/etherdevice.h>
  64 #include <linux/proc_fs.h>
  65 #include <linux/stat.h>
  66 #include <linux/init.h>
  67
  68 #include <net/snmp.h>
  69 #include <net/ip.h>
  70 #include <net/protocol.h>
  71 #include <net/route.h>
  72 #include <net/xfrm.h>
  73 #include <linux/skbuff.h>
  74 #include <net/sock.h>
  75 #include <net/arp.h>
  76 #include <net/icmp.h>
  77 #include <net/checksum.h>
  78 #include <net/inetpeer.h>
  79 #include <net/checksum.h>
  80 #include <linux/igmp.h>
  81 #include <linux/netfilter_ipv4.h>
  82 #include <linux/netfilter_bridge.h>
  83 #include <linux/mroute.h>
  84 #include <linux/netlink.h>
  85 #include <linux/tcp.h>
  86
  87 int sysctl_ip_default_ttl = IPDEFTTL;
  88
  89 /* Generate a checksum for an outgoing IP datagram. */
  90 __inline__ void ip_send_check(struct iphdr *iph)
  91 {
  92         iph->check = 0;
  93         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  94 }
  95
  96 /* dev_loopback_xmit for use with netfilter. */
  97 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
  98 {
  99         newskb->mac.raw = newskb->data;
 100         __skb_pull(newskb, newskb->nh.raw - newskb->data);
 101         newskb->pkt_type = PACKET_LOOPBACK;
 102         newskb->ip_summed = CHECKSUM_UNNECESSARY;
 103         BUG_TRAP(newskb->dst);
 104         netif_rx(newskb);
 105         return 0;
 106 }
 107
 108 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 109 {
 110         int ttl = inet->uc_ttl;
 111
 112         if (ttl < 0)
 113                 ttl = dst_metric(dst, RTAX_HOPLIMIT);
 114         return ttl;
 115 }
 116
 117 /*
 118  *              Add an ip header to a skbuff and send it out.
 119  *
 120  */
 121 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 122                           u32 saddr, u32 daddr, struct ip_options *opt)
 123 {
 124         struct inet_sock *inet = inet_sk(sk);
 125         struct rtable *rt = (struct rtable *)skb->dst;
 126         struct iphdr *iph;
 127
 128         /* Build the IP header. */
 129         if (opt)
 130                 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr) + opt->optlen);
 131         else
 132                 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr));
 133
 134         iph->version  = 4;
 135         iph->ihl      = 5;
 136         iph->tos      = inet->tos;
 137         if (ip_dont_fragment(sk, &rt->u.dst))
 138                 iph->frag_off = htons(IP_DF);
 139         else
 140                 iph->frag_off = 0;
 141         iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
 142         iph->daddr    = rt->rt_dst;
 143         iph->saddr    = rt->rt_src;
 144         iph->protocol = sk->sk_protocol;
 145         iph->tot_len  = htons(skb->len);
 146         ip_select_ident(iph, &rt->u.dst, sk);
 147         skb->nh.iph   = iph;
 148
 149         if (opt && opt->optlen) {
 150                 iph->ihl += opt->optlen>>2;
 151                 ip_options_build(skb, opt, daddr, rt, 0);
 152         }
 153         ip_send_check(iph);
 154
 155         skb->priority = sk->sk_priority;
 156
 157         /* Send it out. */
 158         return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
 159                        dst_output);
 160 }
 161
 162 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 163
 164 static inline int ip_finish_output2(struct sk_buff *skb)
 165 {
 166         struct dst_entry *dst = skb->dst;
 167         struct hh_cache *hh = dst->hh;
 168         struct net_device *dev = dst->dev;
 169         int hh_len = LL_RESERVED_SPACE(dev);
 170
 171         /* Be paranoid, rather than too clever. */
 172         if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) {
 173                 struct sk_buff *skb2;
 174
 175                 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 176                 if (skb2 == NULL) {
 177                         kfree_skb(skb);
 178                         return -ENOMEM;
 179                 }
 180                 if (skb->sk)
 181                         skb_set_owner_w(skb2, skb->sk);
 182                 kfree_skb(skb);
 183                 skb = skb2;
 184         }
 185
 186         if (hh) {
 187                 int hh_alen;
 188
 189                 read_lock_bh(&hh->hh_lock);
 190                 hh_alen = HH_DATA_ALIGN(hh->hh_len);
 191                 memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
 192                 read_unlock_bh(&hh->hh_lock);
 193                 skb_push(skb, hh->hh_len);
 194                 return hh->hh_output(skb);
 195         } else if (dst->neighbour)
 196                 return dst->neighbour->output(skb);
 197
 198         if (net_ratelimit())
 199                 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
 200         kfree_skb(skb);
 201         return -EINVAL;
 202 }
 203
 204 static inline int ip_finish_output(struct sk_buff *skb)
 205 {
 206 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 207         /* Policy lookup after SNAT yielded a new policy */
 208         if (skb->dst->xfrm != NULL) {
 209                 IPCB(skb)->flags |= IPSKB_REROUTED;
 210                 return dst_output(skb);
 211         }
 212 #endif
 213         if (skb->len > dst_mtu(skb->dst) && !skb_shinfo(skb)->gso_size)
 214                 return ip_fragment(skb, ip_finish_output2);
 215         else
 216                 return ip_finish_output2(skb);
 217 }
 218
 219 int ip_mc_output(struct sk_buff *skb)
 220 {
 221         struct sock *sk = skb->sk;
 222         struct rtable *rt = (struct rtable*)skb->dst;
 223         struct net_device *dev = rt->u.dst.dev;
 224
 225         /*
 226          *      If the indicated interface is up and running, send the packet.
 227          */
 228         IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
 229
 230         skb->dev = dev;
 231         skb->protocol = htons(ETH_P_IP);
 232
 233         /*
 234          *      Multicasts are looped back for other local users
 235          */
 236
 237         if (rt->rt_flags&RTCF_MULTICAST) {
 238                 if ((!sk || inet_sk(sk)->mc_loop)
 239 #ifdef CONFIG_IP_MROUTE
 240                 /* Small optimization: do not loopback not local frames,
 241                    which returned after forwarding; they will be  dropped
 242                    by ip_mr_input in any case.
 243                    Note, that local frames are looped back to be delivered
 244                    to local recipients.
 245
 246                    This check is duplicated in ip_mr_input at the moment.
 247                  */
 248                     && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED))
 249 #endif
 250                 ) {
 251                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 252                         if (newskb)
 253                                 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
 254                                         newskb->dev,
 255                                         ip_dev_loopback_xmit);
 256                 }
 257
 258                 /* Multicasts with ttl 0 must not go beyond the host */
 259
 260                 if (skb->nh.iph->ttl == 0) {
 261                         kfree_skb(skb);
 262                         return 0;
 263                 }
 264         }
 265
 266         if (rt->rt_flags&RTCF_BROADCAST) {
 267                 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 268                 if (newskb)
 269                         NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
 270                                 newskb->dev, ip_dev_loopback_xmit);
 271         }
 272
 273         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dev,
 274                             ip_finish_output,
 275                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 276 }
 277
 278 int ip_output(struct sk_buff *skb)
 279 {
 280         struct net_device *dev = skb->dst->dev;
 281
 282         IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
 283
 284         skb->dev = dev;
 285         skb->protocol = htons(ETH_P_IP);
 286
 287         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
 288                             ip_finish_output,
 289                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 290 }
 291
 292 int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
 293 {
 294         struct sock *sk = skb->sk;
 295         struct inet_sock *inet = inet_sk(sk);
 296         struct ip_options *opt = inet->opt;
 297         struct rtable *rt;
 298         struct iphdr *iph;
 299
 300         /* Skip all of this if the packet is already routed,
 301          * f.e. by something like SCTP.
 302          */
 303         rt = (struct rtable *) skb->dst;
 304         if (rt != NULL)
 305                 goto packet_routed;
 306
 307         /* Make sure we can route this packet. */
 308         rt = (struct rtable *)__sk_dst_check(sk, 0);
 309         if (rt == NULL) {
 310                 u32 daddr;
 311
 312                 /* Use correct destination address if we have options. */
 313                 daddr = inet->daddr;
 314                 if(opt && opt->srr)
 315                         daddr = opt->faddr;
 316
 317                 {
 318                         struct flowi fl = { .oif = sk->sk_bound_dev_if,
 319                                             .nl_u = { .ip4_u =
 320                                                       { .daddr = daddr,
 321                                                         .saddr = inet->saddr,
 322                                                         .tos = RT_CONN_FLAGS(sk) } },
 323                                             .proto = sk->sk_protocol,
 324                                             .uli_u = { .ports =
 325                                                        { .sport = inet->sport,
 326                                                          .dport = inet->dport } } };
 327
 328                         /* If this fails, retransmit mechanism of transport layer will
 329                          * keep trying until route appears or the connection times
 330                          * itself out.
 331                          */
 332                         if (ip_route_output_flow(&rt, &fl, sk, 0))
 333                                 goto no_route;
 334                 }
 335                 sk_setup_caps(sk, &rt->u.dst);
 336         }
 337         skb->dst = dst_clone(&rt->u.dst);
 338
 339 packet_routed:
 340         if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
 341                 goto no_route;
 342
 343         /* OK, we know where to send it, allocate and build IP header. */
 344         iph = (struct iphdr *) skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
 345         *((__u16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 346         iph->tot_len = htons(skb->len);
 347         if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
 348                 iph->frag_off = htons(IP_DF);
 349         else
 350                 iph->frag_off = 0;
 351         iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
 352         iph->protocol = sk->sk_protocol;
 353         iph->saddr    = rt->rt_src;
 354         iph->daddr    = rt->rt_dst;
 355         skb->nh.iph   = iph;
 356         /* Transport layer set skb->h.foo itself. */
 357
 358         if (opt && opt->optlen) {
 359                 iph->ihl += opt->optlen >> 2;
 360                 ip_options_build(skb, opt, inet->daddr, rt, 0);
 361         }
 362
 363         ip_select_ident_more(iph, &rt->u.dst, sk,
 364                              (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 365
 366         /* Add an IP checksum. */
 367         ip_send_check(iph);
 368
 369         skb->priority = sk->sk_priority;
 370
 371         return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
 372                        dst_output);
 373
 374 no_route:
 375         IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
 376         kfree_skb(skb);
 377         return -EHOSTUNREACH;
 378 }
 379
 380
 381 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 382 {
 383         to->pkt_type = from->pkt_type;
 384         to->priority = from->priority;
 385         to->protocol = from->protocol;
 386         dst_release(to->dst);
 387         to->dst = dst_clone(from->dst);
 388         to->dev = from->dev;
 389
 390         /* Copy the flags to each fragment. */
 391         IPCB(to)->flags = IPCB(from)->flags;
 392
 393 #ifdef CONFIG_NET_SCHED
 394         to->tc_index = from->tc_index;
 395 #endif
 396 #ifdef CONFIG_NETFILTER
 397         to->nfmark = from->nfmark;
 398         /* Connection association is same as pre-frag packet */
 399         nf_conntrack_put(to->nfct);
 400         to->nfct = from->nfct;
 401         nf_conntrack_get(to->nfct);
 402         to->nfctinfo = from->nfctinfo;
 403 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 404         to->ipvs_property = from->ipvs_property;
 405 #endif
 406 #ifdef CONFIG_BRIDGE_NETFILTER
 407         nf_bridge_put(to->nf_bridge);
 408         to->nf_bridge = from->nf_bridge;
 409         nf_bridge_get(to->nf_bridge);
 410 #endif
 411 #endif
 412         skb_copy_secmark(to, from);
 413 }
 414
 415 /*
 416  *      This IP datagram is too large to be sent in one piece.  Break it up into
 417  *      smaller pieces (each of size equal to IP header plus
 418  *      a block of the data of the original IP data part) that will yet fit in a
 419  *      single device frame, and queue such a frame for sending.
 420  */
 421
 422 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
 423 {
 424         struct iphdr *iph;
 425         int raw = 0;
 426         int ptr;
 427         struct net_device *dev;
 428         struct sk_buff *skb2;
 429         unsigned int mtu, hlen, left, len, ll_rs;
 430         int offset;
 431         __be16 not_last_frag;
 432         struct rtable *rt = (struct rtable*)skb->dst;
 433         int err = 0;
 434
 435         dev = rt->u.dst.dev;
 436
 437         /*
 438          *      Point into the IP datagram header.
 439          */
 440
 441         iph = skb->nh.iph;
 442
 443         if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
 444                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 445                           htonl(dst_mtu(&rt->u.dst)));
 446                 kfree_skb(skb);
 447                 return -EMSGSIZE;
 448         }
 449
 450         /*
 451          *      Setup starting values.
 452          */
 453
 454         hlen = iph->ihl * 4;
 455         mtu = dst_mtu(&rt->u.dst) - hlen;       /* Size of data space */
 456         IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 457
 458         /* When frag_list is given, use it. First, check its validity:
 459          * some transformers could create wrong frag_list or break existing
 460          * one, it is not prohibited. In this case fall back to copying.
 461          *
 462          * LATER: this step can be merged to real generation of fragments,
 463          * we can switch to copy when see the first bad fragment.
 464          */
 465         if (skb_shinfo(skb)->frag_list) {
 466                 struct sk_buff *frag;
 467                 int first_len = skb_pagelen(skb);
 468
 469                 if (first_len - hlen > mtu ||
 470                     ((first_len - hlen) & 7) ||
 471                     (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
 472                     skb_cloned(skb))
 473                         goto slow_path;
 474
 475                 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
 476                         /* Correct geometry. */
 477                         if (frag->len > mtu ||
 478                             ((frag->len & 7) && frag->next) ||
 479                             skb_headroom(frag) < hlen)
 480                             goto slow_path;
 481
 482                         /* Partially cloned skb? */
 483                         if (skb_shared(frag))
 484                                 goto slow_path;
 485
 486                         BUG_ON(frag->sk);
 487                         if (skb->sk) {
 488                                 sock_hold(skb->sk);
 489                                 frag->sk = skb->sk;
 490                                 frag->destructor = sock_wfree;
 491                                 skb->truesize -= frag->truesize;
 492                         }
 493                 }
 494
 495                 /* Everything is OK. Generate! */
 496
 497                 err = 0;
 498                 offset = 0;
 499                 frag = skb_shinfo(skb)->frag_list;
 500                 skb_shinfo(skb)->frag_list = NULL;
 501                 skb->data_len = first_len - skb_headlen(skb);
 502                 skb->len = first_len;
 503                 iph->tot_len = htons(first_len);
 504                 iph->frag_off = htons(IP_MF);
 505                 ip_send_check(iph);
 506
 507                 for (;;) {
 508                         /* Prepare header of the next frame,
 509                          * before previous one went down. */
 510                         if (frag) {
 511                                 frag->ip_summed = CHECKSUM_NONE;
 512                                 frag->h.raw = frag->data;
 513                                 frag->nh.raw = __skb_push(frag, hlen);
 514                                 memcpy(frag->nh.raw, iph, hlen);
 515                                 iph = frag->nh.iph;
 516                                 iph->tot_len = htons(frag->len);
 517                                 ip_copy_metadata(frag, skb);
 518                                 if (offset == 0)
 519                                         ip_options_fragment(frag);
 520                                 offset += skb->len - hlen;
 521                                 iph->frag_off = htons(offset>>3);
 522                                 if (frag->next != NULL)
 523                                         iph->frag_off |= htons(IP_MF);
 524                                 /* Ready, complete checksum */
 525                                 ip_send_check(iph);
 526                         }
 527
 528                         err = output(skb);
 529
 530                         if (err || !frag)
 531                                 break;
 532
 533                         skb = frag;
 534                         frag = skb->next;
 535                         skb->next = NULL;
 536                 }
 537
 538                 if (err == 0) {
 539                         IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
 540                         return 0;
 541                 }
 542
 543                 while (frag) {
 544                         skb = frag->next;
 545                         kfree_skb(frag);
 546                         frag = skb;
 547                 }
 548                 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
 549                 return err;
 550         }
 551
 552 slow_path:
 553         left = skb->len - hlen;         /* Space per frame */
 554         ptr = raw + hlen;               /* Where to start from */
 555
 556 #ifdef CONFIG_BRIDGE_NETFILTER
 557         /* for bridged IP traffic encapsulated inside f.e. a vlan header,
 558          * we need to make room for the encapsulating header */
 559         ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, nf_bridge_pad(skb));
 560         mtu -= nf_bridge_pad(skb);
 561 #else
 562         ll_rs = LL_RESERVED_SPACE(rt->u.dst.dev);
 563 #endif
 564         /*
 565          *      Fragment the datagram.
 566          */
 567
 568         offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 569         not_last_frag = iph->frag_off & htons(IP_MF);
 570
 571         /*
 572          *      Keep copying data until we run out.
 573          */
 574
 575         while(left > 0) {
 576                 len = left;
 577                 /* IF: it doesn't fit, use 'mtu' - the data space left */
 578                 if (len > mtu)
 579                         len = mtu;
 580                 /* IF: we are not sending upto and including the packet end
 581                    then align the next start on an eight byte boundary */
 582                 if (len < left) {
 583                         len &= ~7;
 584                 }
 585                 /*
 586                  *      Allocate buffer.
 587                  */
 588
 589                 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
 590                         NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
 591                         err = -ENOMEM;
 592                         goto fail;
 593                 }
 594
 595                 /*
 596                  *      Set up data on packet
 597                  */
 598
 599                 ip_copy_metadata(skb2, skb);
 600                 skb_reserve(skb2, ll_rs);
 601                 skb_put(skb2, len + hlen);
 602                 skb2->nh.raw = skb2->data;
 603                 skb2->h.raw = skb2->data + hlen;
 604
 605                 /*
 606                  *      Charge the memory for the fragment to any owner
 607                  *      it might possess
 608                  */
 609
 610                 if (skb->sk)
 611                         skb_set_owner_w(skb2, skb->sk);
 612
 613                 /*
 614                  *      Copy the packet header into the new buffer.
 615                  */
 616
 617                 memcpy(skb2->nh.raw, skb->data, hlen);
 618
 619                 /*
 620                  *      Copy a block of the IP datagram.
 621                  */
 622                 if (skb_copy_bits(skb, ptr, skb2->h.raw, len))
 623                         BUG();
 624                 left -= len;
 625
 626                 /*
 627                  *      Fill in the new header fields.
 628                  */
 629                 iph = skb2->nh.iph;
 630                 iph->frag_off = htons((offset >> 3));
 631
 632                 /* ANK: dirty, but effective trick. Upgrade options only if
 633                  * the segment to be fragmented was THE FIRST (otherwise,
 634                  * options are already fixed) and make it ONCE
 635                  * on the initial skb, so that all the following fragments
 636                  * will inherit fixed options.
 637                  */
 638                 if (offset == 0)
 639                         ip_options_fragment(skb);
 640
 641                 /*
 642                  *      Added AC : If we are fragmenting a fragment that's not the
 643                  *                 last fragment then keep MF on each bit
 644                  */
 645                 if (left > 0 || not_last_frag)
 646                         iph->frag_off |= htons(IP_MF);
 647                 ptr += len;
 648                 offset += len;
 649
 650                 /*
 651                  *      Put this fragment into the sending queue.
 652                  */
 653
 654                 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
 655
 656                 iph->tot_len = htons(len + hlen);
 657
 658                 ip_send_check(iph);
 659
 660                 err = output(skb2);
 661                 if (err)
 662                         goto fail;
 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_shinfo(skb)->gso_size)
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);