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 static int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*));
  90
  91 /* Generate a checksum for an outgoing IP datagram. */
  92 __inline__ void ip_send_check(struct iphdr *iph)
  93 {
  94         iph->check = 0;
  95         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  96 }
  97
  98 /* dev_loopback_xmit for use with netfilter. */
  99 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
 100 {
 101         newskb->mac.raw = newskb->data;
 102         __skb_pull(newskb, newskb->nh.raw - newskb->data);
 103         newskb->pkt_type = PACKET_LOOPBACK;
 104         newskb->ip_summed = CHECKSUM_UNNECESSARY;
 105         BUG_TRAP(newskb->dst);
 106         netif_rx(newskb);
 107         return 0;
 108 }
 109
 110 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 111 {
 112         int ttl = inet->uc_ttl;
 113
 114         if (ttl < 0)
 115                 ttl = dst_metric(dst, RTAX_HOPLIMIT);
 116         return ttl;
 117 }
 118
 119 /*
 120  *              Add an ip header to a skbuff and send it out.
 121  *
 122  */
 123 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 124                           u32 saddr, u32 daddr, struct ip_options *opt)
 125 {
 126         struct inet_sock *inet = inet_sk(sk);
 127         struct rtable *rt = (struct rtable *)skb->dst;
 128         struct iphdr *iph;
 129
 130         /* Build the IP header. */
 131         if (opt)
 132                 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr) + opt->optlen);
 133         else
 134                 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr));
 135
 136         iph->version  = 4;
 137         iph->ihl      = 5;
 138         iph->tos      = inet->tos;
 139         if (ip_dont_fragment(sk, &rt->u.dst))
 140                 iph->frag_off = htons(IP_DF);
 141         else
 142                 iph->frag_off = 0;
 143         iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
 144         iph->daddr    = rt->rt_dst;
 145         iph->saddr    = rt->rt_src;
 146         iph->protocol = sk->sk_protocol;
 147         iph->tot_len  = htons(skb->len);
 148         ip_select_ident(iph, &rt->u.dst, sk);
 149         skb->nh.iph   = iph;
 150
 151         if (opt && opt->optlen) {
 152                 iph->ihl += opt->optlen>>2;
 153                 ip_options_build(skb, opt, daddr, rt, 0);
 154         }
 155         ip_send_check(iph);
 156
 157         skb->priority = sk->sk_priority;
 158
 159         /* Send it out. */
 160         return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
 161                        dst_output);
 162 }
 163
 164 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 165
 166 static inline int ip_finish_output2(struct sk_buff *skb)
 167 {
 168         struct dst_entry *dst = skb->dst;
 169         struct hh_cache *hh = dst->hh;
 170         struct net_device *dev = dst->dev;
 171         int hh_len = LL_RESERVED_SPACE(dev);
 172
 173         /* Be paranoid, rather than too clever. */
 174         if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) {
 175                 struct sk_buff *skb2;
 176
 177                 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 178                 if (skb2 == NULL) {
 179                         kfree_skb(skb);
 180                         return -ENOMEM;
 181                 }
 182                 if (skb->sk)
 183                         skb_set_owner_w(skb2, skb->sk);
 184                 kfree_skb(skb);
 185                 skb = skb2;
 186         }
 187
 188         if (hh) {
 189                 int hh_alen;
 190
 191                 read_lock_bh(&hh->hh_lock);
 192                 hh_alen = HH_DATA_ALIGN(hh->hh_len);
 193                 memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
 194                 read_unlock_bh(&hh->hh_lock);
 195                 skb_push(skb, hh->hh_len);
 196                 return hh->hh_output(skb);
 197         } else if (dst->neighbour)
 198                 return dst->neighbour->output(skb);
 199
 200         if (net_ratelimit())
 201                 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
 202         kfree_skb(skb);
 203         return -EINVAL;
 204 }
 205
 206 static inline int ip_finish_output(struct sk_buff *skb)
 207 {
 208 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 209         /* Policy lookup after SNAT yielded a new policy */
 210         if (skb->dst->xfrm != NULL) {
 211                 IPCB(skb)->flags |= IPSKB_REROUTED;
 212                 return dst_output(skb);
 213         }
 214 #endif
 215         if (skb->len > dst_mtu(skb->dst) &&
 216             !(skb_shinfo(skb)->ufo_size || skb_shinfo(skb)->tso_size))
 217                 return ip_fragment(skb, ip_finish_output2);
 218         else
 219                 return ip_finish_output2(skb);
 220 }
 221
 222 int ip_mc_output(struct sk_buff *skb)
 223 {
 224         struct sock *sk = skb->sk;
 225         struct rtable *rt = (struct rtable*)skb->dst;
 226         struct net_device *dev = rt->u.dst.dev;
 227
 228         /*
 229          *      If the indicated interface is up and running, send the packet.
 230          */
 231         IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
 232
 233         skb->dev = dev;
 234         skb->protocol = htons(ETH_P_IP);
 235
 236         /*
 237          *      Multicasts are looped back for other local users
 238          */
 239
 240         if (rt->rt_flags&RTCF_MULTICAST) {
 241                 if ((!sk || inet_sk(sk)->mc_loop)
 242 #ifdef CONFIG_IP_MROUTE
 243                 /* Small optimization: do not loopback not local frames,
 244                    which returned after forwarding; they will be  dropped
 245                    by ip_mr_input in any case.
 246                    Note, that local frames are looped back to be delivered
 247                    to local recipients.
 248
 249                    This check is duplicated in ip_mr_input at the moment.
 250                  */
 251                     && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED))
 252 #endif
 253                 ) {
 254                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 255                         if (newskb)
 256                                 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
 257                                         newskb->dev,
 258                                         ip_dev_loopback_xmit);
 259                 }
 260
 261                 /* Multicasts with ttl 0 must not go beyond the host */
 262
 263                 if (skb->nh.iph->ttl == 0) {
 264                         kfree_skb(skb);
 265                         return 0;
 266                 }
 267         }
 268
 269         if (rt->rt_flags&RTCF_BROADCAST) {
 270                 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 271                 if (newskb)
 272                         NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
 273                                 newskb->dev, ip_dev_loopback_xmit);
 274         }
 275
 276         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dev,
 277                             ip_finish_output,
 278                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 279 }
 280
 281 int ip_output(struct sk_buff *skb)
 282 {
 283         struct net_device *dev = skb->dst->dev;
 284
 285         IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
 286
 287         skb->dev = dev;
 288         skb->protocol = htons(ETH_P_IP);
 289
 290         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
 291                             ip_finish_output,
 292                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 293 }
 294
 295 int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
 296 {
 297         struct sock *sk = skb->sk;
 298         struct inet_sock *inet = inet_sk(sk);
 299         struct ip_options *opt = inet->opt;
 300         struct rtable *rt;
 301         struct iphdr *iph;
 302
 303         /* Skip all of this if the packet is already routed,
 304          * f.e. by something like SCTP.
 305          */
 306         rt = (struct rtable *) skb->dst;
 307         if (rt != NULL)
 308                 goto packet_routed;
 309
 310         /* Make sure we can route this packet. */
 311         rt = (struct rtable *)__sk_dst_check(sk, 0);
 312         if (rt == NULL) {
 313                 u32 daddr;
 314
 315                 /* Use correct destination address if we have options. */
 316                 daddr = inet->daddr;
 317                 if(opt && opt->srr)
 318                         daddr = opt->faddr;
 319
 320                 {
 321                         struct flowi fl = { .oif = sk->sk_bound_dev_if,
 322                                             .nl_u = { .ip4_u =
 323                                                       { .daddr = daddr,
 324                                                         .saddr = inet->saddr,
 325                                                         .tos = RT_CONN_FLAGS(sk) } },
 326                                             .proto = sk->sk_protocol,
 327                                             .uli_u = { .ports =
 328                                                        { .sport = inet->sport,
 329                                                          .dport = inet->dport } } };
 330
 331                         /* If this fails, retransmit mechanism of transport layer will
 332                          * keep trying until route appears or the connection times
 333                          * itself out.
 334                          */
 335                         if (ip_route_output_flow(&rt, &fl, sk, 0))
 336                                 goto no_route;
 337                 }
 338                 sk_setup_caps(sk, &rt->u.dst);
 339         }
 340         skb->dst = dst_clone(&rt->u.dst);
 341
 342 packet_routed:
 343         if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
 344                 goto no_route;
 345
 346         /* OK, we know where to send it, allocate and build IP header. */
 347         iph = (struct iphdr *) skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
 348         *((__u16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 349         iph->tot_len = htons(skb->len);
 350         if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
 351                 iph->frag_off = htons(IP_DF);
 352         else
 353                 iph->frag_off = 0;
 354         iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
 355         iph->protocol = sk->sk_protocol;
 356         iph->saddr    = rt->rt_src;
 357         iph->daddr    = rt->rt_dst;
 358         skb->nh.iph   = iph;
 359         /* Transport layer set skb->h.foo itself. */
 360
 361         if (opt && opt->optlen) {
 362                 iph->ihl += opt->optlen >> 2;
 363                 ip_options_build(skb, opt, inet->daddr, rt, 0);
 364         }
 365
 366         ip_select_ident_more(iph, &rt->u.dst, sk,
 367                              (skb_shinfo(skb)->tso_segs ?: 1) - 1);
 368
 369         /* Add an IP checksum. */
 370         ip_send_check(iph);
 371
 372         skb->priority = sk->sk_priority;
 373
 374         return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
 375                        dst_output);
 376
 377 no_route:
 378         IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
 379         kfree_skb(skb);
 380         return -EHOSTUNREACH;
 381 }
 382
 383
 384 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 385 {
 386         to->pkt_type = from->pkt_type;
 387         to->priority = from->priority;
 388         to->protocol = from->protocol;
 389         dst_release(to->dst);
 390         to->dst = dst_clone(from->dst);
 391         to->dev = from->dev;
 392
 393         /* Copy the flags to each fragment. */
 394         IPCB(to)->flags = IPCB(from)->flags;
 395
 396 #ifdef CONFIG_NET_SCHED
 397         to->tc_index = from->tc_index;
 398 #endif
 399 #ifdef CONFIG_NETFILTER
 400         to->nfmark = from->nfmark;
 401         /* Connection association is same as pre-frag packet */
 402         nf_conntrack_put(to->nfct);
 403         to->nfct = from->nfct;
 404         nf_conntrack_get(to->nfct);
 405         to->nfctinfo = from->nfctinfo;
 406 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 407         to->ipvs_property = from->ipvs_property;
 408 #endif
 409 #ifdef CONFIG_BRIDGE_NETFILTER
 410         nf_bridge_put(to->nf_bridge);
 411         to->nf_bridge = from->nf_bridge;
 412         nf_bridge_get(to->nf_bridge);
 413 #endif
 414 #endif
 415 }
 416
 417 /*
 418  *      This IP datagram is too large to be sent in one piece.  Break it up into
 419  *      smaller pieces (each of size equal to IP header plus
 420  *      a block of the data of the original IP data part) that will yet fit in a
 421  *      single device frame, and queue such a frame for sending.
 422  */
 423
 424 static int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
 425 {
 426         struct iphdr *iph;
 427         int raw = 0;
 428         int ptr;
 429         struct net_device *dev;
 430         struct sk_buff *skb2;
 431         unsigned int mtu, hlen, left, len, ll_rs;
 432         int offset;
 433         __be16 not_last_frag;
 434         struct rtable *rt = (struct rtable*)skb->dst;
 435         int err = 0;
 436
 437         dev = rt->u.dst.dev;
 438
 439         /*
 440          *      Point into the IP datagram header.
 441          */
 442
 443         iph = skb->nh.iph;
 444
 445         if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
 446                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 447                           htonl(dst_mtu(&rt->u.dst)));
 448                 kfree_skb(skb);
 449                 return -EMSGSIZE;
 450         }
 451
 452         /*
 453          *      Setup starting values.
 454          */
 455
 456         hlen = iph->ihl * 4;
 457         mtu = dst_mtu(&rt->u.dst) - hlen;       /* Size of data space */
 458         IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 459
 460         /* When frag_list is given, use it. First, check its validity:
 461          * some transformers could create wrong frag_list or break existing
 462          * one, it is not prohibited. In this case fall back to copying.
 463          *
 464          * LATER: this step can be merged to real generation of fragments,
 465          * we can switch to copy when see the first bad fragment.
 466          */
 467         if (skb_shinfo(skb)->frag_list) {
 468                 struct sk_buff *frag;
 469                 int first_len = skb_pagelen(skb);
 470
 471                 if (first_len - hlen > mtu ||
 472                     ((first_len - hlen) & 7) ||
 473                     (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
 474                     skb_cloned(skb))
 475                         goto slow_path;
 476
 477                 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
 478                         /* Correct geometry. */
 479                         if (frag->len > mtu ||
 480                             ((frag->len & 7) && frag->next) ||
 481                             skb_headroom(frag) < hlen)
 482                             goto slow_path;
 483
 484                         /* Partially cloned skb? */
 485                         if (skb_shared(frag))
 486                                 goto slow_path;
 487
 488                         BUG_ON(frag->sk);
 489                         if (skb->sk) {
 490                                 sock_hold(skb->sk);
 491                                 frag->sk = skb->sk;
 492                                 frag->destructor = sock_wfree;
 493                                 skb->truesize -= frag->truesize;
 494                         }
 495                 }
 496
 497                 /* Everything is OK. Generate! */
 498
 499                 err = 0;
 500                 offset = 0;
 501                 frag = skb_shinfo(skb)->frag_list;
 502                 skb_shinfo(skb)->frag_list = NULL;
 503                 skb->data_len = first_len - skb_headlen(skb);
 504                 skb->len = first_len;
 505                 iph->tot_len = htons(first_len);
 506                 iph->frag_off = htons(IP_MF);
 507                 ip_send_check(iph);
 508
 509                 for (;;) {
 510                         /* Prepare header of the next frame,
 511                          * before previous one went down. */
 512                         if (frag) {
 513                                 frag->ip_summed = CHECKSUM_NONE;
 514                                 frag->h.raw = frag->data;
 515                                 frag->nh.raw = __skb_push(frag, hlen);
 516                                 memcpy(frag->nh.raw, iph, hlen);
 517                                 iph = frag->nh.iph;
 518                                 iph->tot_len = htons(frag->len);
 519                                 ip_copy_metadata(frag, skb);
 520                                 if (offset == 0)
 521                                         ip_options_fragment(frag);
 522                                 offset += skb->len - hlen;
 523                                 iph->frag_off = htons(offset>>3);
 524                                 if (frag->next != NULL)
 525                                         iph->frag_off |= htons(IP_MF);
 526                                 /* Ready, complete checksum */
 527                                 ip_send_check(iph);
 528                         }
 529
 530                         err = output(skb);
 531
 532                         if (err || !frag)
 533                                 break;
 534
 535                         skb = frag;
 536                         frag = skb->next;
 537                         skb->next = NULL;
 538                 }
 539
 540                 if (err == 0) {
 541                         IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
 542                         return 0;
 543                 }
 544
 545                 while (frag) {
 546                         skb = frag->next;
 547                         kfree_skb(frag);
 548                         frag = skb;
 549                 }
 550                 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
 551                 return err;
 552         }
 553
 554 slow_path:
 555         left = skb->len - hlen;         /* Space per frame */
 556         ptr = raw + hlen;               /* Where to start from */
 557
 558 #ifdef CONFIG_BRIDGE_NETFILTER
 559         /* for bridged IP traffic encapsulated inside f.e. a vlan header,
 560          * we need to make room for the encapsulating header */
 561         ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, nf_bridge_pad(skb));
 562         mtu -= nf_bridge_pad(skb);
 563 #else
 564         ll_rs = LL_RESERVED_SPACE(rt->u.dst.dev);
 565 #endif
 566         /*
 567          *      Fragment the datagram.
 568          */
 569
 570         offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 571         not_last_frag = iph->frag_off & htons(IP_MF);
 572
 573         /*
 574          *      Keep copying data until we run out.
 575          */
 576
 577         while(left > 0) {
 578                 len = left;
 579                 /* IF: it doesn't fit, use 'mtu' - the data space left */
 580                 if (len > mtu)
 581                         len = mtu;
 582                 /* IF: we are not sending upto and including the packet end
 583                    then align the next start on an eight byte boundary */
 584                 if (len < left) {
 585                         len &= ~7;
 586                 }
 587                 /*
 588                  *      Allocate buffer.
 589                  */
 590
 591                 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
 592                         NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
 593                         err = -ENOMEM;
 594                         goto fail;
 595                 }
 596
 597                 /*
 598                  *      Set up data on packet
 599                  */
 600
 601                 ip_copy_metadata(skb2, skb);
 602                 skb_reserve(skb2, ll_rs);
 603                 skb_put(skb2, len + hlen);
 604                 skb2->nh.raw = skb2->data;
 605                 skb2->h.raw = skb2->data + hlen;
 606
 607                 /*
 608                  *      Charge the memory for the fragment to any owner
 609                  *      it might possess
 610                  */
 611
 612                 if (skb->sk)
 613                         skb_set_owner_w(skb2, skb->sk);
 614
 615                 /*
 616                  *      Copy the packet header into the new buffer.
 617                  */
 618
 619                 memcpy(skb2->nh.raw, skb->data, hlen);
 620
 621                 /*
 622                  *      Copy a block of the IP datagram.
 623                  */
 624                 if (skb_copy_bits(skb, ptr, skb2->h.raw, len))
 625                         BUG();
 626                 left -= len;
 627
 628                 /*
 629                  *      Fill in the new header fields.
 630                  */
 631                 iph = skb2->nh.iph;
 632                 iph->frag_off = htons((offset >> 3));
 633
 634                 /* ANK: dirty, but effective trick. Upgrade options only if
 635                  * the segment to be fragmented was THE FIRST (otherwise,
 636                  * options are already fixed) and make it ONCE
 637                  * on the initial skb, so that all the following fragments
 638                  * will inherit fixed options.
 639                  */
 640                 if (offset == 0)
 641                         ip_options_fragment(skb);
 642
 643                 /*
 644                  *      Added AC : If we are fragmenting a fragment that's not the
 645                  *                 last fragment then keep MF on each bit
 646                  */
 647                 if (left > 0 || not_last_frag)
 648                         iph->frag_off |= htons(IP_MF);
 649                 ptr += len;
 650                 offset += len;
 651
 652                 /*
 653                  *      Put this fragment into the sending queue.
 654                  */
 655
 656                 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
 657
 658                 iph->tot_len = htons(len + hlen);
 659
 660                 ip_send_check(iph);
 661
 662                 err = output(skb2);
 663                 if (err)
 664                         goto fail;
 665         }
 666         kfree_skb(skb);
 667         IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
 668         return err;
 669
 670 fail:
 671         kfree_skb(skb);
 672         IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
 673         return err;
 674 }
 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)->ufo_size = (mtu - fragheaderlen);
 747                 __skb_queue_tail(&sk->sk_write_queue, skb);
 748
 749                 return 0;
 750         }
 751         /* There is not enough support do UFO ,
 752          * so follow normal path
 753          */
 754         kfree_skb(skb);
 755         return err;
 756 }
 757
 758 /*
 759  *      ip_append_data() and ip_append_page() can make one large IP datagram
 760  *      from many pieces of data. Each pieces will be holded on the socket
 761  *      until ip_push_pending_frames() is called. Each piece can be a page
 762  *      or non-page data.
 763  *
 764  *      Not only UDP, other transport protocols - e.g. raw sockets - can use
 765  *      this interface potentially.
 766  *
 767  *      LATER: length must be adjusted by pad at tail, when it is required.
 768  */
 769 int ip_append_data(struct sock *sk,
 770                    int getfrag(void *from, char *to, int offset, int len,
 771                                int odd, struct sk_buff *skb),
 772                    void *from, int length, int transhdrlen,
 773                    struct ipcm_cookie *ipc, struct rtable *rt,
 774                    unsigned int flags)
 775 {
 776         struct inet_sock *inet = inet_sk(sk);
 777         struct sk_buff *skb;
 778
 779         struct ip_options *opt = NULL;
 780         int hh_len;
 781         int exthdrlen;
 782         int mtu;
 783         int copy;
 784         int err;
 785         int offset = 0;
 786         unsigned int maxfraglen, fragheaderlen;
 787         int csummode = CHECKSUM_NONE;
 788
 789         if (flags&MSG_PROBE)
 790                 return 0;
 791
 792         if (skb_queue_empty(&sk->sk_write_queue)) {
 793                 /*
 794                  * setup for corking.
 795                  */
 796                 opt = ipc->opt;
 797                 if (opt) {
 798                         if (inet->cork.opt == NULL) {
 799                                 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
 800                                 if (unlikely(inet->cork.opt == NULL))
 801                                         return -ENOBUFS;
 802                         }
 803                         memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen);
 804                         inet->cork.flags |= IPCORK_OPT;
 805                         inet->cork.addr = ipc->addr;
 806                 }
 807                 dst_hold(&rt->u.dst);
 808                 inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path);
 809                 inet->cork.rt = rt;
 810                 inet->cork.length = 0;
 811                 sk->sk_sndmsg_page = NULL;
 812                 sk->sk_sndmsg_off = 0;
 813                 if ((exthdrlen = rt->u.dst.header_len) != 0) {
 814                         length += exthdrlen;
 815                         transhdrlen += exthdrlen;
 816                 }
 817         } else {
 818                 rt = inet->cork.rt;
 819                 if (inet->cork.flags & IPCORK_OPT)
 820                         opt = inet->cork.opt;
 821
 822                 transhdrlen = 0;
 823                 exthdrlen = 0;
 824                 mtu = inet->cork.fragsize;
 825         }
 826         hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
 827
 828         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 829         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 830
 831         if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
 832                 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen);
 833                 return -EMSGSIZE;
 834         }
 835
 836         /*
 837          * transhdrlen > 0 means that this is the first fragment and we wish
 838          * it won't be fragmented in the future.
 839          */
 840         if (transhdrlen &&
 841             length + fragheaderlen <= mtu &&
 842             rt->u.dst.dev->features&(NETIF_F_IP_CSUM|NETIF_F_NO_CSUM|NETIF_F_HW_CSUM) &&
 843             !exthdrlen)
 844                 csummode = CHECKSUM_HW;
 845
 846         inet->cork.length += length;
 847         if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
 848                         (rt->u.dst.dev->features & NETIF_F_UFO)) {
 849
 850                 if(ip_ufo_append_data(sk, getfrag, from, length, hh_len,
 851                                fragheaderlen, transhdrlen, mtu, flags))
 852                         goto error;
 853
 854                 return 0;
 855         }
 856
 857         /* So, what's going on in the loop below?
 858          *
 859          * We use calculated fragment length to generate chained skb,
 860          * each of segments is IP fragment ready for sending to network after
 861          * adding appropriate IP header.
 862          */
 863
 864         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
 865                 goto alloc_new_skb;
 866
 867         while (length > 0) {
 868                 /* Check if the remaining data fits into current packet. */
 869                 copy = mtu - skb->len;
 870                 if (copy < length)
 871                         copy = maxfraglen - skb->len;
 872                 if (copy <= 0) {
 873                         char *data;
 874                         unsigned int datalen;
 875                         unsigned int fraglen;
 876                         unsigned int fraggap;
 877                         unsigned int alloclen;
 878                         struct sk_buff *skb_prev;
 879 alloc_new_skb:
 880                         skb_prev = skb;
 881                         if (skb_prev)
 882                                 fraggap = skb_prev->len - maxfraglen;
 883                         else
 884                                 fraggap = 0;
 885
 886                         /*
 887                          * If remaining data exceeds the mtu,
 888                          * we know we need more fragment(s).
 889                          */
 890                         datalen = length + fraggap;
 891                         if (datalen > mtu - fragheaderlen)
 892                                 datalen = maxfraglen - fragheaderlen;
 893                         fraglen = datalen + fragheaderlen;
 894
 895                         if ((flags & MSG_MORE) &&
 896                             !(rt->u.dst.dev->features&NETIF_F_SG))
 897                                 alloclen = mtu;
 898                         else
 899                                 alloclen = datalen + fragheaderlen;
 900
 901                         /* The last fragment gets additional space at tail.
 902                          * Note, with MSG_MORE we overallocate on fragments,
 903                          * because we have no idea what fragment will be
 904                          * the last.
 905                          */
 906                         if (datalen == length)
 907                                 alloclen += rt->u.dst.trailer_len;
 908
 909                         if (transhdrlen) {
 910                                 skb = sock_alloc_send_skb(sk,
 911                                                 alloclen + hh_len + 15,
 912                                                 (flags & MSG_DONTWAIT), &err);
 913                         } else {
 914                                 skb = NULL;
 915                                 if (atomic_read(&sk->sk_wmem_alloc) <=
 916                                     2 * sk->sk_sndbuf)
 917                                         skb = sock_wmalloc(sk,
 918                                                            alloclen + hh_len + 15, 1,
 919                                                            sk->sk_allocation);
 920                                 if (unlikely(skb == NULL))
 921                                         err = -ENOBUFS;
 922                         }
 923                         if (skb == NULL)
 924                                 goto error;
 925
 926                         /*
 927                          *      Fill in the control structures
 928                          */
 929                         skb->ip_summed = csummode;
 930                         skb->csum = 0;
 931                         skb_reserve(skb, hh_len);
 932
 933                         /*
 934                          *      Find where to start putting bytes.
 935                          */
 936                         data = skb_put(skb, fraglen);
 937                         skb->nh.raw = data + exthdrlen;
 938                         data += fragheaderlen;
 939                         skb->h.raw = data + exthdrlen;
 940
 941                         if (fraggap) {
 942                                 skb->csum = skb_copy_and_csum_bits(
 943                                         skb_prev, maxfraglen,
 944                                         data + transhdrlen, fraggap, 0);
 945                                 skb_prev->csum = csum_sub(skb_prev->csum,
 946                                                           skb->csum);
 947                                 data += fraggap;
 948                                 skb_trim(skb_prev, maxfraglen);
 949                         }
 950
 951                         copy = datalen - transhdrlen - fraggap;
 952                         if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
 953                                 err = -EFAULT;
 954                                 kfree_skb(skb);
 955                                 goto error;
 956                         }
 957
 958                         offset += copy;
 959                         length -= datalen - fraggap;
 960                         transhdrlen = 0;
 961                         exthdrlen = 0;
 962                         csummode = CHECKSUM_NONE;
 963
 964                         /*
 965                          * Put the packet on the pending queue.
 966                          */
 967                         __skb_queue_tail(&sk->sk_write_queue, skb);
 968                         continue;
 969                 }
 970
 971                 if (copy > length)
 972                         copy = length;
 973
 974                 if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
 975                         unsigned int off;
 976
 977                         off = skb->len;
 978                         if (getfrag(from, skb_put(skb, copy),
 979                                         offset, copy, off, skb) < 0) {
 980                                 __skb_trim(skb, off);
 981                                 err = -EFAULT;
 982                                 goto error;
 983                         }
 984                 } else {
 985                         int i = skb_shinfo(skb)->nr_frags;
 986                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
 987                         struct page *page = sk->sk_sndmsg_page;
 988                         int off = sk->sk_sndmsg_off;
 989                         unsigned int left;
 990
 991                         if (page && (left = PAGE_SIZE - off) > 0) {
 992                                 if (copy >= left)
 993                                         copy = left;
 994                                 if (page != frag->page) {
 995                                         if (i == MAX_SKB_FRAGS) {
 996                                                 err = -EMSGSIZE;
 997                                                 goto error;
 998                                         }
 999                                         get_page(page);
1000                                         skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
1001                                         frag = &skb_shinfo(skb)->frags[i];
1002                                 }
1003                         } else if (i < MAX_SKB_FRAGS) {
1004                                 if (copy > PAGE_SIZE)
1005                                         copy = PAGE_SIZE;
1006                                 page = alloc_pages(sk->sk_allocation, 0);
1007                                 if (page == NULL)  {
1008                                         err = -ENOMEM;
1009                                         goto error;
1010                                 }
1011                                 sk->sk_sndmsg_page = page;
1012                                 sk->sk_sndmsg_off = 0;
1013
1014                                 skb_fill_page_desc(skb, i, page, 0, 0);
1015                                 frag = &skb_shinfo(skb)->frags[i];
1016                                 skb->truesize += PAGE_SIZE;
1017                                 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
1018                         } else {
1019                                 err = -EMSGSIZE;
1020                                 goto error;
1021                         }
1022                         if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1023                                 err = -EFAULT;
1024                                 goto error;
1025                         }
1026                         sk->sk_sndmsg_off += copy;
1027                         frag->size += copy;
1028                         skb->len += copy;
1029                         skb->data_len += copy;
1030                 }
1031                 offset += copy;
1032                 length -= copy;
1033         }
1034
1035         return 0;
1036
1037 error:
1038         inet->cork.length -= length;
1039         IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1040         return err;
1041 }
1042
1043 ssize_t ip_append_page(struct sock *sk, struct page *page,
1044                        int offset, size_t size, int flags)
1045 {
1046         struct inet_sock *inet = inet_sk(sk);
1047         struct sk_buff *skb;
1048         struct rtable *rt;
1049         struct ip_options *opt = NULL;
1050         int hh_len;
1051         int mtu;
1052         int len;
1053         int err;
1054         unsigned int maxfraglen, fragheaderlen, fraggap;
1055
1056         if (inet->hdrincl)
1057                 return -EPERM;
1058
1059         if (flags&MSG_PROBE)
1060                 return 0;
1061
1062         if (skb_queue_empty(&sk->sk_write_queue))
1063                 return -EINVAL;
1064
1065         rt = inet->cork.rt;
1066         if (inet->cork.flags & IPCORK_OPT)
1067                 opt = inet->cork.opt;
1068
1069         if (!(rt->u.dst.dev->features&NETIF_F_SG))
1070                 return -EOPNOTSUPP;
1071
1072         hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
1073         mtu = inet->cork.fragsize;
1074
1075         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1076         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1077
1078         if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
1079                 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu);
1080                 return -EMSGSIZE;
1081         }
1082
1083         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1084                 return -EINVAL;
1085
1086         inet->cork.length += size;
1087         if ((sk->sk_protocol == IPPROTO_UDP) &&
1088             (rt->u.dst.dev->features & NETIF_F_UFO))
1089                 skb_shinfo(skb)->ufo_size = (mtu - fragheaderlen);
1090
1091
1092         while (size > 0) {
1093                 int i;
1094
1095                 if (skb_shinfo(skb)->ufo_size)
1096                         len = size;
1097                 else {
1098
1099                         /* Check if the remaining data fits into current packet. */
1100                         len = mtu - skb->len;
1101                         if (len < size)
1102                                 len = maxfraglen - skb->len;
1103                 }
1104                 if (len <= 0) {
1105                         struct sk_buff *skb_prev;
1106                         char *data;
1107                         struct iphdr *iph;
1108                         int alloclen;
1109
1110                         skb_prev = skb;
1111                         fraggap = skb_prev->len - maxfraglen;
1112
1113                         alloclen = fragheaderlen + hh_len + fraggap + 15;
1114                         skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1115                         if (unlikely(!skb)) {
1116                                 err = -ENOBUFS;
1117                                 goto error;
1118                         }
1119
1120                         /*
1121                          *      Fill in the control structures
1122                          */
1123                         skb->ip_summed = CHECKSUM_NONE;
1124                         skb->csum = 0;
1125                         skb_reserve(skb, hh_len);
1126
1127                         /*
1128                          *      Find where to start putting bytes.
1129                          */
1130                         data = skb_put(skb, fragheaderlen + fraggap);
1131                         skb->nh.iph = iph = (struct iphdr *)data;
1132                         data += fragheaderlen;
1133                         skb->h.raw = data;
1134
1135                         if (fraggap) {
1136                                 skb->csum = skb_copy_and_csum_bits(
1137                                         skb_prev, maxfraglen,
1138                                         data, fraggap, 0);
1139                                 skb_prev->csum = csum_sub(skb_prev->csum,
1140                                                           skb->csum);
1141                                 skb_trim(skb_prev, maxfraglen);
1142                         }
1143
1144                         /*
1145                          * Put the packet on the pending queue.
1146                          */
1147                         __skb_queue_tail(&sk->sk_write_queue, skb);
1148                         continue;
1149                 }
1150
1151                 i = skb_shinfo(skb)->nr_frags;
1152                 if (len > size)
1153                         len = size;
1154                 if (skb_can_coalesce(skb, i, page, offset)) {
1155                         skb_shinfo(skb)->frags[i-1].size += len;
1156                 } else if (i < MAX_SKB_FRAGS) {
1157                         get_page(page);
1158                         skb_fill_page_desc(skb, i, page, offset, len);
1159                 } else {
1160                         err = -EMSGSIZE;
1161                         goto error;
1162                 }
1163
1164                 if (skb->ip_summed == CHECKSUM_NONE) {
1165                         unsigned int csum;
1166                         csum = csum_page(page, offset, len);
1167                         skb->csum = csum_block_add(skb->csum, csum, skb->len);
1168                 }
1169
1170                 skb->len += len;
1171                 skb->data_len += len;
1172                 offset += len;
1173                 size -= len;
1174         }
1175         return 0;
1176
1177 error:
1178         inet->cork.length -= size;
1179         IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1180         return err;
1181 }
1182
1183 /*
1184  *      Combined all pending IP fragments on the socket as one IP datagram
1185  *      and push them out.
1186  */
1187 int ip_push_pending_frames(struct sock *sk)
1188 {
1189         struct sk_buff *skb, *tmp_skb;
1190         struct sk_buff **tail_skb;
1191         struct inet_sock *inet = inet_sk(sk);
1192         struct ip_options *opt = NULL;
1193         struct rtable *rt = inet->cork.rt;
1194         struct iphdr *iph;
1195         __be16 df = 0;
1196         __u8 ttl;
1197         int err = 0;
1198
1199         if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1200                 goto out;
1201         tail_skb = &(skb_shinfo(skb)->frag_list);
1202
1203         /* move skb->data to ip header from ext header */
1204         if (skb->data < skb->nh.raw)
1205                 __skb_pull(skb, skb->nh.raw - skb->data);
1206         while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1207                 __skb_pull(tmp_skb, skb->h.raw - skb->nh.raw);
1208                 *tail_skb = tmp_skb;
1209                 tail_skb = &(tmp_skb->next);
1210                 skb->len += tmp_skb->len;
1211                 skb->data_len += tmp_skb->len;
1212                 skb->truesize += tmp_skb->truesize;
1213                 __sock_put(tmp_skb->sk);
1214                 tmp_skb->destructor = NULL;
1215                 tmp_skb->sk = NULL;
1216         }
1217
1218         /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1219          * to fragment the frame generated here. No matter, what transforms
1220          * how transforms change size of the packet, it will come out.
1221          */
1222         if (inet->pmtudisc != IP_PMTUDISC_DO)
1223                 skb->local_df = 1;
1224
1225         /* DF bit is set when we want to see DF on outgoing frames.
1226          * If local_df is set too, we still allow to fragment this frame
1227          * locally. */
1228         if (inet->pmtudisc == IP_PMTUDISC_DO ||
1229             (skb->len <= dst_mtu(&rt->u.dst) &&
1230              ip_dont_fragment(sk, &rt->u.dst)))
1231                 df = htons(IP_DF);
1232
1233         if (inet->cork.flags & IPCORK_OPT)
1234                 opt = inet->cork.opt;
1235
1236         if (rt->rt_type == RTN_MULTICAST)
1237                 ttl = inet->mc_ttl;
1238         else
1239                 ttl = ip_select_ttl(inet, &rt->u.dst);
1240
1241         iph = (struct iphdr *)skb->data;
1242         iph->version = 4;
1243         iph->ihl = 5;
1244         if (opt) {
1245                 iph->ihl += opt->optlen>>2;
1246                 ip_options_build(skb, opt, inet->cork.addr, rt, 0);
1247         }
1248         iph->tos = inet->tos;
1249         iph->tot_len = htons(skb->len);
1250         iph->frag_off = df;
1251         if (!df) {
1252                 __ip_select_ident(iph, &rt->u.dst, 0);
1253         } else {
1254                 iph->id = htons(inet->id++);
1255         }
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);