sys/netgraph7/ng_vjc.c

   1
   2 /*
   3  * ng_vjc.c
   4  */
   5
   6 /*-
   7  * Copyright (c) 1996-1999 Whistle Communications, Inc.
   8  * All rights reserved.
   9  *
  10  * Subject to the following obligations and disclaimer of warranty, use and
  11  * redistribution of this software, in source or object code forms, with or
  12  * without modifications are expressly permitted by Whistle Communications;
  13  * provided, however, that:
  14  * 1. Any and all reproductions of the source or object code must include the
  15  *    copyright notice above and the following disclaimer of warranties; and
  16  * 2. No rights are granted, in any manner or form, to use Whistle
  17  *    Communications, Inc. trademarks, including the mark "WHISTLE
  18  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
  19  *    such appears in the above copyright notice or in the software.
  20  *
  21  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
  22  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
  23  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
  24  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
  26  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
  27  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
  28  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
  29  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
  30  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
  31  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  32  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
  33  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
  34  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  35  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  36  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
  37  * OF SUCH DAMAGE.
  38  *
  39  * Author: Archie Cobbs <archie@freebsd.org>
  40  *
  41  * $FreeBSD: src/sys/netgraph/ng_vjc.c,v 1.26 2005/12/04 00:25:03 ru Exp $
  42  * $DragonFly: src/sys/netgraph7/ng_vjc.c,v 1.2 2008/06/26 23:05:35 dillon Exp $
  43  * $Whistle: ng_vjc.c,v 1.17 1999/11/01 09:24:52 julian Exp $
  44  */
  45
  46 /*
  47  * This node performs Van Jacobson IP header (de)compression.
  48  * You must have included net/slcompress.c in your kernel compilation.
  49  */
  50
  51 #include <sys/param.h>
  52 #include <sys/systm.h>
  53 #include <sys/errno.h>
  54 #include <sys/kernel.h>
  55 #include <sys/mbuf.h>
  56 #include <sys/malloc.h>
  57 #include <sys/errno.h>
  58
  59 #include "ng_message.h"
  60 #include "netgraph.h"
  61 #include "ng_parse.h"
  62 #include "ng_vjc.h"
  63
  64 #include <netinet/in.h>
  65 #include <netinet/in_systm.h>
  66 #include <netinet/ip.h>
  67 #include <netinet/tcp.h>
  68
  69 #include <net/slcompress.h>
  70
  71 /* Check agreement with slcompress.c */
  72 #if MAX_STATES != NG_VJC_MAX_CHANNELS
  73 #error NG_VJC_MAX_CHANNELS must be the same as MAX_STATES
  74 #endif
  75
  76 /* Maximum length of a compressed TCP VJ header */
  77 #define MAX_VJHEADER            19
  78
  79 /* Node private data */
  80 struct ng_vjc_private {
  81         struct  ngm_vjc_config conf;
  82         struct  slcompress slc;
  83         hook_p  ip;
  84         hook_p  vjcomp;
  85         hook_p  vjuncomp;
  86         hook_p  vjip;
  87 };
  88 typedef struct ng_vjc_private *priv_p;
  89
  90 #define ERROUT(x)       do { error = (x); goto done; } while (0)
  91
  92 /* Netgraph node methods */
  93 static ng_constructor_t ng_vjc_constructor;
  94 static ng_rcvmsg_t      ng_vjc_rcvmsg;
  95 static ng_shutdown_t    ng_vjc_shutdown;
  96 static ng_newhook_t     ng_vjc_newhook;
  97 static ng_rcvdata_t     ng_vjc_rcvdata;
  98 static ng_disconnect_t  ng_vjc_disconnect;
  99
 100 /* Helper stuff */
 101 static struct mbuf *ng_vjc_pulluphdrs(struct mbuf *m, int knownTCP);
 102
 103 /* Parse type for struct ngm_vjc_config */
 104 static const struct ng_parse_struct_field ng_vjc_config_type_fields[]
 105         = NG_VJC_CONFIG_TYPE_INFO;
 106 static const struct ng_parse_type ng_vjc_config_type = {
 107         &ng_parse_struct_type,
 108         &ng_vjc_config_type_fields
 109 };
 110
 111 /* Parse type for the 'last_cs' and 'cs_next' fields in struct slcompress,
 112    which are pointers converted to integer indices, so parse them that way. */
 113 #ifndef __LP64__
 114 #define NG_VJC_TSTATE_PTR_TYPE  &ng_parse_uint32_type
 115 #else
 116 #define NG_VJC_TSTATE_PTR_TYPE  &ng_parse_uint64_type
 117 #endif
 118
 119 /* Parse type for the 'cs_hdr' field in a struct cstate. Ideally we would
 120    like to use a 'struct ip' type instead of a simple array of bytes. */
 121 static const struct ng_parse_fixedarray_info ng_vjc_cs_hdr_type_info = {
 122         &ng_parse_hint8_type,
 123         MAX_HDR
 124 };
 125 static const struct ng_parse_type ng_vjc_cs_hdr_type = {
 126         &ng_parse_fixedarray_type,
 127         &ng_vjc_cs_hdr_type_info
 128 };
 129
 130 /* Parse type for a struct cstate */
 131 static const struct ng_parse_struct_field ng_vjc_cstate_type_fields[] = {
 132         { "cs_next",            NG_VJC_TSTATE_PTR_TYPE          },
 133         { "cs_hlen",            &ng_parse_uint16_type           },
 134         { "cs_id",              &ng_parse_uint8_type            },
 135         { "cs_filler",          &ng_parse_uint8_type            },
 136         { "cs_hdr",             &ng_vjc_cs_hdr_type             },
 137         { NULL }
 138 };
 139 static const struct ng_parse_type ng_vjc_cstate_type = {
 140         &ng_parse_struct_type,
 141         &ng_vjc_cstate_type_fields
 142 };
 143
 144 /* Parse type for an array of MAX_STATES struct cstate's, ie, tstate & rstate */
 145 static const struct ng_parse_fixedarray_info ng_vjc_cstatearray_type_info = {
 146         &ng_vjc_cstate_type,
 147         MAX_STATES
 148 };
 149 static const struct ng_parse_type ng_vjc_cstatearray_type = {
 150         &ng_parse_fixedarray_type,
 151         &ng_vjc_cstatearray_type_info
 152 };
 153
 154 /* Parse type for struct slcompress. Keep this in sync with the
 155    definition of struct slcompress defined in <net/slcompress.h> */
 156 static const struct ng_parse_struct_field ng_vjc_slcompress_type_fields[] = {
 157         { "last_cs",            NG_VJC_TSTATE_PTR_TYPE          },
 158         { "last_recv",          &ng_parse_uint8_type            },
 159         { "last_xmit",          &ng_parse_uint8_type            },
 160         { "flags",              &ng_parse_hint16_type           },
 161 #ifndef SL_NO_STATS
 162         { "sls_packets",        &ng_parse_uint32_type           },
 163         { "sls_compressed",     &ng_parse_uint32_type           },
 164         { "sls_searches",       &ng_parse_uint32_type           },
 165         { "sls_misses",         &ng_parse_uint32_type           },
 166         { "sls_uncompressedin", &ng_parse_uint32_type           },
 167         { "sls_compressedin",   &ng_parse_uint32_type           },
 168         { "sls_errorin",        &ng_parse_uint32_type           },
 169         { "sls_tossed",         &ng_parse_uint32_type           },
 170 #endif
 171         { "tstate",             &ng_vjc_cstatearray_type        },
 172         { "rstate",             &ng_vjc_cstatearray_type        },
 173         { NULL }
 174 };
 175 static const struct ng_parse_type ng_vjc_slcompress_type = {
 176         &ng_parse_struct_type,
 177         &ng_vjc_slcompress_type_fields
 178 };
 179
 180 /* List of commands and how to convert arguments to/from ASCII */
 181 static const struct ng_cmdlist ng_vjc_cmds[] = {
 182         {
 183           NGM_VJC_COOKIE,
 184           NGM_VJC_SET_CONFIG,
 185           "setconfig",
 186           &ng_vjc_config_type,
 187           NULL
 188         },
 189         {
 190           NGM_VJC_COOKIE,
 191           NGM_VJC_GET_CONFIG,
 192           "getconfig",
 193           NULL,
 194           &ng_vjc_config_type,
 195         },
 196         {
 197           NGM_VJC_COOKIE,
 198           NGM_VJC_GET_STATE,
 199           "getstate",
 200           NULL,
 201           &ng_vjc_slcompress_type,
 202         },
 203         {
 204           NGM_VJC_COOKIE,
 205           NGM_VJC_CLR_STATS,
 206           "clrstats",
 207           NULL,
 208           NULL,
 209         },
 210         {
 211           NGM_VJC_COOKIE,
 212           NGM_VJC_RECV_ERROR,
 213           "recverror",
 214           NULL,
 215           NULL,
 216         },
 217         { 0 }
 218 };
 219
 220 /* Node type descriptor */
 221 static struct ng_type ng_vjc_typestruct = {
 222         .version =      NG_ABI_VERSION,
 223         .name =         NG_VJC_NODE_TYPE,
 224         .constructor =  ng_vjc_constructor,
 225         .rcvmsg =       ng_vjc_rcvmsg,
 226         .shutdown =     ng_vjc_shutdown,
 227         .newhook =      ng_vjc_newhook,
 228         .rcvdata =      ng_vjc_rcvdata,
 229         .disconnect =   ng_vjc_disconnect,
 230         .cmdlist =      ng_vjc_cmds,
 231 };
 232 NETGRAPH_INIT(vjc, &ng_vjc_typestruct);
 233
 234 /************************************************************************
 235                         NETGRAPH NODE METHODS
 236  ************************************************************************/
 237
 238 /*
 239  * Create a new node
 240  */
 241 static int
 242 ng_vjc_constructor(node_p node)
 243 {
 244         priv_p priv;
 245
 246         /* Allocate private structure */
 247         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH, M_WAITOK | M_NULLOK | M_ZERO);
 248         if (priv == NULL)
 249                 return (ENOMEM);
 250
 251         NG_NODE_SET_PRIVATE(node, priv);
 252
 253         /* Done */
 254         return (0);
 255 }
 256
 257 /*
 258  * Add a new hook
 259  */
 260 static int
 261 ng_vjc_newhook(node_p node, hook_p hook, const char *name)
 262 {
 263         const priv_p priv = NG_NODE_PRIVATE(node);
 264         hook_p *hookp;
 265
 266         /* Get hook */
 267         if (strcmp(name, NG_VJC_HOOK_IP) == 0)
 268                 hookp = &priv->ip;
 269         else if (strcmp(name, NG_VJC_HOOK_VJCOMP) == 0)
 270                 hookp = &priv->vjcomp;
 271         else if (strcmp(name, NG_VJC_HOOK_VJUNCOMP) == 0)
 272                 hookp = &priv->vjuncomp;
 273         else if (strcmp(name, NG_VJC_HOOK_VJIP) == 0)
 274                 hookp = &priv->vjip;
 275         else
 276                 return (EINVAL);
 277
 278         /* See if already connected */
 279         if (*hookp)
 280                 return (EISCONN);
 281
 282         /* OK */
 283         *hookp = hook;
 284         return (0);
 285 }
 286
 287 /*
 288  * Receive a control message
 289  */
 290 static int
 291 ng_vjc_rcvmsg(node_p node, item_p item, hook_p lasthook)
 292 {
 293         const priv_p priv = NG_NODE_PRIVATE(node);
 294         struct ng_mesg *resp = NULL;
 295         int error = 0;
 296         struct ng_mesg *msg;
 297
 298         NGI_GET_MSG(item, msg);
 299         /* Check type cookie */
 300         switch (msg->header.typecookie) {
 301         case NGM_VJC_COOKIE:
 302                 switch (msg->header.cmd) {
 303                 case NGM_VJC_SET_CONFIG:
 304                     {
 305                         struct ngm_vjc_config *const c =
 306                                 (struct ngm_vjc_config *) msg->data;
 307
 308                         if (msg->header.arglen != sizeof(*c))
 309                                 ERROUT(EINVAL);
 310                         if ((priv->conf.enableComp || priv->conf.enableDecomp)
 311                             && (c->enableComp || c->enableDecomp))
 312                                 ERROUT(EALREADY);
 313                         if (c->enableComp) {
 314                                 if (c->maxChannel > NG_VJC_MAX_CHANNELS - 1
 315                                     || c->maxChannel < NG_VJC_MIN_CHANNELS - 1)
 316                                         ERROUT(EINVAL);
 317                         } else
 318                                 c->maxChannel = NG_VJC_MAX_CHANNELS - 1;
 319                         if (c->enableComp != 0 || c->enableDecomp != 0) {
 320                                 bzero(&priv->slc, sizeof(priv->slc));
 321                                 sl_compress_init(&priv->slc, c->maxChannel);
 322                         }
 323                         priv->conf = *c;
 324                         break;
 325                     }
 326                 case NGM_VJC_GET_CONFIG:
 327                     {
 328                         struct ngm_vjc_config *conf;
 329
 330                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_WAITOK | M_NULLOK);
 331                         if (resp == NULL)
 332                                 ERROUT(ENOMEM);
 333                         conf = (struct ngm_vjc_config *)resp->data;
 334                         *conf = priv->conf;
 335                         break;
 336                     }
 337                 case NGM_VJC_GET_STATE:
 338                     {
 339                         const struct slcompress *const sl0 = &priv->slc;
 340                         struct slcompress *sl;
 341                         u_int16_t index;
 342                         int i;
 343
 344                         /* Get response structure */
 345                         NG_MKRESPONSE(resp, msg, sizeof(*sl), M_WAITOK | M_NULLOK);
 346                         if (resp == NULL)
 347                                 ERROUT(ENOMEM);
 348                         sl = (struct slcompress *)resp->data;
 349                         *sl = *sl0;
 350
 351                         /* Replace pointers with integer indicies */
 352                         if (sl->last_cs != NULL) {
 353                                 index = sl0->last_cs - sl0->tstate;
 354                                 bzero(&sl->last_cs, sizeof(sl->last_cs));
 355                                 *((u_int16_t *)&sl->last_cs) = index;
 356                         }
 357                         for (i = 0; i < MAX_STATES; i++) {
 358                                 struct cstate *const cs = &sl->tstate[i];
 359
 360                                 index = sl0->tstate[i].cs_next - sl0->tstate;
 361                                 bzero(&cs->cs_next, sizeof(cs->cs_next));
 362                                 *((u_int16_t *)&cs->cs_next) = index;
 363                         }
 364                         break;
 365                     }
 366                 case NGM_VJC_CLR_STATS:
 367                         priv->slc.sls_packets = 0;
 368                         priv->slc.sls_compressed = 0;
 369                         priv->slc.sls_searches = 0;
 370                         priv->slc.sls_misses = 0;
 371                         priv->slc.sls_uncompressedin = 0;
 372                         priv->slc.sls_compressedin = 0;
 373                         priv->slc.sls_errorin = 0;
 374                         priv->slc.sls_tossed = 0;
 375                         break;
 376                 case NGM_VJC_RECV_ERROR:
 377                         sl_uncompress_tcp(NULL, 0, TYPE_ERROR, &priv->slc);
 378                         break;
 379                 default:
 380                         error = EINVAL;
 381                         break;
 382                 }
 383                 break;
 384         default:
 385                 error = EINVAL;
 386                 break;
 387         }
 388 done:
 389         NG_RESPOND_MSG(error, node, item, resp);
 390         NG_FREE_MSG(msg);
 391         return (error);
 392 }
 393
 394 /*
 395  * Receive data
 396  */
 397 static int
 398 ng_vjc_rcvdata(hook_p hook, item_p item)
 399 {
 400         const node_p node = NG_HOOK_NODE(hook);
 401         const priv_p priv = NG_NODE_PRIVATE(node);
 402         int error = 0;
 403         struct mbuf *m;
 404
 405         NGI_GET_M(item, m);
 406         if (hook == priv->ip) {                 /* outgoing packet */
 407                 u_int type = TYPE_IP;
 408
 409                 /* Compress packet if enabled and proto is TCP */
 410                 if (priv->conf.enableComp) {
 411                         struct ip *ip;
 412
 413                         if ((m = ng_vjc_pulluphdrs(m, 0)) == NULL) {
 414                                 NG_FREE_ITEM(item);
 415                                 return (ENOBUFS);
 416                         }
 417                         ip = mtod(m, struct ip *);
 418                         if (ip->ip_p == IPPROTO_TCP) {
 419                                 const int origLen = m->m_len;
 420
 421                                 type = sl_compress_tcp(m, ip,
 422                                     &priv->slc, priv->conf.compressCID);
 423                                 m->m_pkthdr.len += m->m_len - origLen;
 424                         }
 425                 }
 426
 427                 /* Dispatch to the appropriate outgoing hook */
 428                 switch (type) {
 429                 case TYPE_IP:
 430                         hook = priv->vjip;
 431                         break;
 432                 case TYPE_UNCOMPRESSED_TCP:
 433                         hook = priv->vjuncomp;
 434                         break;
 435                 case TYPE_COMPRESSED_TCP:
 436                         hook = priv->vjcomp;
 437                         break;
 438                 default:
 439                         panic("%s: type=%d", __func__, type);
 440                 }
 441         } else if (hook == priv->vjcomp) {      /* incoming compressed packet */
 442                 int vjlen, need2pullup;
 443                 struct mbuf *hm;
 444                 u_char *hdr;
 445                 u_int hlen;
 446
 447                 /* Are we decompressing? */
 448                 if (!priv->conf.enableDecomp) {
 449                         NG_FREE_M(m);
 450                         NG_FREE_ITEM(item);
 451                         return (ENXIO);
 452                 }
 453
 454                 /* Pull up the necessary amount from the mbuf */
 455                 need2pullup = MAX_VJHEADER;
 456                 if (need2pullup > m->m_pkthdr.len)
 457                         need2pullup = m->m_pkthdr.len;
 458                 if (m->m_len < need2pullup
 459                     && (m = m_pullup(m, need2pullup)) == NULL) {
 460                         priv->slc.sls_errorin++;
 461                         NG_FREE_ITEM(item);
 462                         return (ENOBUFS);
 463                 }
 464
 465                 /* Uncompress packet to reconstruct TCP/IP header */
 466                 vjlen = sl_uncompress_tcp_core(mtod(m, u_char *),
 467                     m->m_len, m->m_pkthdr.len, TYPE_COMPRESSED_TCP,
 468                     &priv->slc, &hdr, &hlen);
 469                 if (vjlen <= 0) {
 470                         NG_FREE_M(m);
 471                         NG_FREE_ITEM(item);
 472                         return (EINVAL);
 473                 }
 474                 m_adj(m, vjlen);
 475
 476                 /* Copy the reconstructed TCP/IP headers into a new mbuf */
 477                 MGETHDR(hm, MB_DONTWAIT, MT_DATA);
 478                 if (hm == NULL) {
 479                         priv->slc.sls_errorin++;
 480                         NG_FREE_M(m);
 481                         NG_FREE_ITEM(item);
 482                         return (ENOBUFS);
 483                 }
 484                 hm->m_len = 0;
 485                 hm->m_pkthdr.rcvif = NULL;
 486                 if (hlen > MHLEN) {             /* unlikely, but can happen */
 487                         MCLGET(hm, MB_DONTWAIT);
 488                         if ((hm->m_flags & M_EXT) == 0) {
 489                                 m_freem(hm);
 490                                 priv->slc.sls_errorin++;
 491                                 NG_FREE_M(m);
 492                                 NG_FREE_ITEM(item);
 493                                 return (ENOBUFS);
 494                         }
 495                 }
 496                 bcopy(hdr, mtod(hm, u_char *), hlen);
 497                 hm->m_len = hlen;
 498
 499                 /* Glue TCP/IP headers and rest of packet together */
 500                 hm->m_next = m;
 501                 hm->m_pkthdr.len = hlen + m->m_pkthdr.len;
 502                 m = hm;
 503                 hook = priv->ip;
 504         } else if (hook == priv->vjuncomp) {    /* incoming uncompressed pkt */
 505                 u_char *hdr;
 506                 u_int hlen;
 507
 508                 /* Are we decompressing? */
 509                 if (!priv->conf.enableDecomp) {
 510                         NG_FREE_M(m);
 511                         NG_FREE_ITEM(item);
 512                         return (ENXIO);
 513                 }
 514
 515                 /* Pull up IP+TCP headers */
 516                 if ((m = ng_vjc_pulluphdrs(m, 1)) == NULL) {
 517                         NG_FREE_ITEM(item);
 518                         return (ENOBUFS);
 519                 }
 520
 521                 /* Run packet through uncompressor */
 522                 if (sl_uncompress_tcp_core(mtod(m, u_char *),
 523                     m->m_len, m->m_pkthdr.len, TYPE_UNCOMPRESSED_TCP,
 524                     &priv->slc, &hdr, &hlen) < 0) {
 525                         NG_FREE_M(m);
 526                         NG_FREE_ITEM(item);
 527                         return (EINVAL);
 528                 }
 529                 hook = priv->ip;
 530         } else if (hook == priv->vjip)  /* incoming regular packet (bypass) */
 531                 hook = priv->ip;
 532         else
 533                 panic("%s: unknown hook", __func__);
 534
 535         /* Send result back out */
 536         NG_FWD_NEW_DATA(error, item, hook, m);
 537         return (error);
 538 }
 539
 540 /*
 541  * Shutdown node
 542  */
 543 static int
 544 ng_vjc_shutdown(node_p node)
 545 {
 546         const priv_p priv = NG_NODE_PRIVATE(node);
 547
 548         bzero(priv, sizeof(*priv));
 549         FREE(priv, M_NETGRAPH);
 550         NG_NODE_SET_PRIVATE(node, NULL);
 551         NG_NODE_UNREF(node);
 552         return (0);
 553 }
 554
 555 /*
 556  * Hook disconnection
 557  */
 558 static int
 559 ng_vjc_disconnect(hook_p hook)
 560 {
 561         const node_p node = NG_HOOK_NODE(hook);
 562         const priv_p priv = NG_NODE_PRIVATE(node);
 563
 564         /* Zero out hook pointer */
 565         if (hook == priv->ip)
 566                 priv->ip = NULL;
 567         else if (hook == priv->vjcomp)
 568                 priv->vjcomp = NULL;
 569         else if (hook == priv->vjuncomp)
 570                 priv->vjuncomp = NULL;
 571         else if (hook == priv->vjip)
 572                 priv->vjip = NULL;
 573         else
 574                 panic("%s: unknown hook", __func__);
 575
 576         /* Go away if no hooks left */
 577         if ((NG_NODE_NUMHOOKS(node) == 0)
 578         && (NG_NODE_IS_VALID(node)))
 579                 ng_rmnode_self(node);
 580         return (0);
 581 }
 582
 583 /************************************************************************
 584                         HELPER STUFF
 585  ************************************************************************/
 586
 587 /*
 588  * Pull up the full IP and TCP headers of a packet. If packet is not
 589  * a TCP packet, just pull up the IP header.
 590  */
 591 static struct mbuf *
 592 ng_vjc_pulluphdrs(struct mbuf *m, int knownTCP)
 593 {
 594         struct ip *ip;
 595         struct tcphdr *tcp;
 596         int ihlen, thlen;
 597
 598         if (m->m_len < sizeof(*ip) && (m = m_pullup(m, sizeof(*ip))) == NULL)
 599                 return (NULL);
 600         ip = mtod(m, struct ip *);
 601         if (!knownTCP && ip->ip_p != IPPROTO_TCP)
 602                 return (m);
 603         ihlen = ip->ip_hl << 2;
 604         if (m->m_len < ihlen + sizeof(*tcp)) {
 605                 if ((m = m_pullup(m, ihlen + sizeof(*tcp))) == NULL)
 606                         return (NULL);
 607                 ip = mtod(m, struct ip *);
 608         }
 609         tcp = (struct tcphdr *)((u_char *)ip + ihlen);
 610         thlen = tcp->th_off << 2;
 611         if (m->m_len < ihlen + thlen)
 612                 m = m_pullup(m, ihlen + thlen);
 613         return (m);
 614 }
 615