sys/netgraph/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  * $FreeBSD$
  42  * $Whistle: ng_vjc.c,v 1.17 1999/11/01 09:24:52 julian Exp $
  43  */
  44
  45 /*
  46  * This node performs Van Jacobson IP header (de)compression.
  47  * You must have included net/slcompress.c in your kernel compilation.
  48  */
  49
  50 #include <sys/param.h>
  51 #include <sys/systm.h>
  52 #include <sys/errno.h>
  53 #include <sys/kernel.h>
  54 #include <sys/mbuf.h>
  55 #include <sys/malloc.h>
  56 #include <sys/errno.h>
  57
  58 #include <netgraph/ng_message.h>
  59 #include <netgraph/netgraph.h>
  60 #include <netgraph/ng_parse.h>
  61 #include <netgraph/ng_vjc.h>
  62
  63 #include <netinet/in.h>
  64 #include <netinet/in_systm.h>
  65 #include <netinet/ip.h>
  66 #include <netinet/tcp.h>
  67
  68 #include <net/slcompress.h>
  69
  70 /* Check agreement with slcompress.c */
  71 #if MAX_STATES != NG_VJC_MAX_CHANNELS
  72 #error NG_VJC_MAX_CHANNELS must be the same as MAX_STATES
  73 #endif
  74
  75 /* Maximum length of a compressed TCP VJ header */
  76 #define MAX_VJHEADER            19
  77
  78 /* Node private data */
  79 struct ng_vjc_private {
  80         struct  ngm_vjc_config conf;
  81         struct  slcompress slc;
  82         hook_p  ip;
  83         hook_p  vjcomp;
  84         hook_p  vjuncomp;
  85         hook_p  vjip;
  86 };
  87 typedef struct ng_vjc_private *priv_p;
  88
  89 #define ERROUT(x)       do { error = (x); goto done; } while (0)
  90
  91 /* Netgraph node methods */
  92 static ng_constructor_t ng_vjc_constructor;
  93 static ng_rcvmsg_t      ng_vjc_rcvmsg;
  94 static ng_shutdown_t    ng_vjc_shutdown;
  95 static ng_newhook_t     ng_vjc_newhook;
  96 static ng_rcvdata_t     ng_vjc_rcvdata;
  97 static ng_disconnect_t  ng_vjc_disconnect;
  98
  99 /* Helper stuff */
 100 static struct mbuf *ng_vjc_pulluphdrs(struct mbuf *m, int knownTCP);
 101
 102 /* Parse type for struct ngm_vjc_config */
 103 static const struct ng_parse_struct_field ng_vjc_config_type_fields[]
 104         = NG_VJC_CONFIG_TYPE_INFO;
 105 static const struct ng_parse_type ng_vjc_config_type = {
 106         &ng_parse_struct_type,
 107         &ng_vjc_config_type_fields
 108 };
 109
 110 /* Parse type for the 'last_cs' and 'cs_next' fields in struct slcompress,
 111    which are pointers converted to integer indices, so parse them that way. */
 112 #if _MACHINE_ARCH == i386
 113 #define NG_VJC_TSTATE_PTR_TYPE  &ng_parse_uint32_type
 114 #elif _MACHINE_ARCH == alpha
 115 #define NG_VJC_TSTATE_PTR_TYPE  &ng_parse_uint64_type
 116 #else
 117 #error Unspported _MACHINE_ARCH
 118 #endif
 119
 120 /* Parse type for the 'cs_hdr' field in a struct cstate. Ideally we would
 121    like to use a 'struct ip' type instead of a simple array of bytes. */
 122 static const struct ng_parse_fixedarray_info ng_vjc_cs_hdr_type_info = {
 123         &ng_parse_hint8_type,
 124         MAX_HDR
 125 };
 126 static const struct ng_parse_type ng_vjc_cs_hdr_type = {
 127         &ng_parse_fixedarray_type,
 128         &ng_vjc_cs_hdr_type_info
 129 };
 130
 131 /* Parse type for a struct cstate */
 132 static const struct ng_parse_struct_field ng_vjc_cstate_type_fields[] = {
 133         { "cs_next",            NG_VJC_TSTATE_PTR_TYPE          },
 134         { "cs_hlen",            &ng_parse_uint16_type           },
 135         { "cs_id",              &ng_parse_uint8_type            },
 136         { "cs_filler",          &ng_parse_uint8_type            },
 137         { "cs_hdr",             &ng_vjc_cs_hdr_type             },
 138         { NULL }
 139 };
 140 static const struct ng_parse_type ng_vjc_cstate_type = {
 141         &ng_parse_struct_type,
 142         &ng_vjc_cstate_type_fields
 143 };
 144
 145 /* Parse type for an array of MAX_STATES struct cstate's, ie, tstate & rstate */
 146 static const struct ng_parse_fixedarray_info ng_vjc_cstatearray_type_info = {
 147         &ng_vjc_cstate_type,
 148         MAX_STATES
 149 };
 150 static const struct ng_parse_type ng_vjc_cstatearray_type = {
 151         &ng_parse_fixedarray_type,
 152         &ng_vjc_cstatearray_type_info
 153 };
 154
 155 /* Parse type for struct slcompress. Keep this in sync with the
 156    definition of struct slcompress defined in <net/slcompress.h> */
 157 static const struct ng_parse_struct_field ng_vjc_slcompress_type_fields[] = {
 158         { "last_cs",            NG_VJC_TSTATE_PTR_TYPE          },
 159         { "last_recv",          &ng_parse_uint8_type            },
 160         { "last_xmit",          &ng_parse_uint8_type            },
 161         { "flags",              &ng_parse_hint16_type           },
 162 #ifndef SL_NO_STATS
 163         { "sls_packets",        &ng_parse_uint32_type           },
 164         { "sls_compressed",     &ng_parse_uint32_type           },
 165         { "sls_searches",       &ng_parse_uint32_type           },
 166         { "sls_misses",         &ng_parse_uint32_type           },
 167         { "sls_uncompressedin", &ng_parse_uint32_type           },
 168         { "sls_compressedin",   &ng_parse_uint32_type           },
 169         { "sls_errorin",        &ng_parse_uint32_type           },
 170         { "sls_tossed",         &ng_parse_uint32_type           },
 171 #endif
 172         { "tstate",             &ng_vjc_cstatearray_type        },
 173         { "rstate",             &ng_vjc_cstatearray_type        },
 174         { NULL }
 175 };
 176 static const struct ng_parse_type ng_vjc_slcompress_type = {
 177         &ng_parse_struct_type,
 178         &ng_vjc_slcompress_type_fields
 179 };
 180
 181 /* List of commands and how to convert arguments to/from ASCII */
 182 static const struct ng_cmdlist ng_vjc_cmds[] = {
 183         {
 184           NGM_VJC_COOKIE,
 185           NGM_VJC_SET_CONFIG,
 186           "setconfig",
 187           &ng_vjc_config_type,
 188           NULL
 189         },
 190         {
 191           NGM_VJC_COOKIE,
 192           NGM_VJC_GET_CONFIG,
 193           "getconfig",
 194           NULL,
 195           &ng_vjc_config_type,
 196         },
 197         {
 198           NGM_VJC_COOKIE,
 199           NGM_VJC_GET_STATE,
 200           "getstate",
 201           NULL,
 202           &ng_vjc_slcompress_type,
 203         },
 204         {
 205           NGM_VJC_COOKIE,
 206           NGM_VJC_CLR_STATS,
 207           "clrstats",
 208           NULL,
 209           NULL,
 210         },
 211         {
 212           NGM_VJC_COOKIE,
 213           NGM_VJC_RECV_ERROR,
 214           "recverror",
 215           NULL,
 216           NULL,
 217         },
 218         { 0 }
 219 };
 220
 221 /* Node type descriptor */
 222 static struct ng_type ng_vjc_typestruct = {
 223         .version =      NG_ABI_VERSION,
 224         .name =         NG_VJC_NODE_TYPE,
 225         .constructor =  ng_vjc_constructor,
 226         .rcvmsg =       ng_vjc_rcvmsg,
 227         .shutdown =     ng_vjc_shutdown,
 228         .newhook =      ng_vjc_newhook,
 229         .rcvdata =      ng_vjc_rcvdata,
 230         .disconnect =   ng_vjc_disconnect,
 231         .cmdlist =      ng_vjc_cmds,
 232 };
 233 NETGRAPH_INIT(vjc, &ng_vjc_typestruct);
 234
 235 /************************************************************************
 236                         NETGRAPH NODE METHODS
 237  ************************************************************************/
 238
 239 /*
 240  * Create a new node
 241  */
 242 static int
 243 ng_vjc_constructor(node_p node)
 244 {
 245         priv_p priv;
 246
 247         /* Allocate private structure */
 248         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH, M_NOWAIT | M_ZERO);
 249         if (priv == NULL)
 250                 return (ENOMEM);
 251
 252         NG_NODE_SET_PRIVATE(node, priv);
 253
 254         /* Done */
 255         return (0);
 256 }
 257
 258 /*
 259  * Add a new hook
 260  */
 261 static int
 262 ng_vjc_newhook(node_p node, hook_p hook, const char *name)
 263 {
 264         const priv_p priv = NG_NODE_PRIVATE(node);
 265         hook_p *hookp;
 266
 267         /* Get hook */
 268         if (strcmp(name, NG_VJC_HOOK_IP) == 0)
 269                 hookp = &priv->ip;
 270         else if (strcmp(name, NG_VJC_HOOK_VJCOMP) == 0)
 271                 hookp = &priv->vjcomp;
 272         else if (strcmp(name, NG_VJC_HOOK_VJUNCOMP) == 0)
 273                 hookp = &priv->vjuncomp;
 274         else if (strcmp(name, NG_VJC_HOOK_VJIP) == 0)
 275                 hookp = &priv->vjip;
 276         else
 277                 return (EINVAL);
 278
 279         /* See if already connected */
 280         if (*hookp)
 281                 return (EISCONN);
 282
 283         /* OK */
 284         *hookp = hook;
 285         return (0);
 286 }
 287
 288 /*
 289  * Receive a control message
 290  */
 291 static int
 292 ng_vjc_rcvmsg(node_p node, item_p item, hook_p lasthook)
 293 {
 294         const priv_p priv = NG_NODE_PRIVATE(node);
 295         struct ng_mesg *resp = NULL;
 296         int error = 0;
 297         struct ng_mesg *msg;
 298
 299         NGI_GET_MSG(item, msg);
 300         /* Check type cookie */
 301         switch (msg->header.typecookie) {
 302         case NGM_VJC_COOKIE:
 303                 switch (msg->header.cmd) {
 304                 case NGM_VJC_SET_CONFIG:
 305                     {
 306                         struct ngm_vjc_config *const c =
 307                                 (struct ngm_vjc_config *) msg->data;
 308
 309                         if (msg->header.arglen != sizeof(*c))
 310                                 ERROUT(EINVAL);
 311                         if ((priv->conf.enableComp || priv->conf.enableDecomp)
 312                             && (c->enableComp || c->enableDecomp))
 313                                 ERROUT(EALREADY);
 314                         if (c->enableComp) {
 315                                 if (c->maxChannel > NG_VJC_MAX_CHANNELS - 1
 316                                     || c->maxChannel < NG_VJC_MIN_CHANNELS - 1)
 317                                         ERROUT(EINVAL);
 318                         } else
 319                                 c->maxChannel = NG_VJC_MAX_CHANNELS - 1;
 320                         if (c->enableComp != 0 || c->enableDecomp != 0) {
 321                                 bzero(&priv->slc, sizeof(priv->slc));
 322                                 sl_compress_init(&priv->slc, c->maxChannel);
 323                         }
 324                         priv->conf = *c;
 325                         break;
 326                     }
 327                 case NGM_VJC_GET_CONFIG:
 328                     {
 329                         struct ngm_vjc_config *conf;
 330
 331                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
 332                         if (resp == NULL)
 333                                 ERROUT(ENOMEM);
 334                         conf = (struct ngm_vjc_config *)resp->data;
 335                         *conf = priv->conf;
 336                         break;
 337                     }
 338                 case NGM_VJC_GET_STATE:
 339                     {
 340                         const struct slcompress *const sl0 = &priv->slc;
 341                         struct slcompress *sl;
 342                         u_int16_t index;
 343                         int i;
 344
 345                         /* Get response structure */
 346                         NG_MKRESPONSE(resp, msg, sizeof(*sl), M_NOWAIT);
 347                         if (resp == NULL)
 348                                 ERROUT(ENOMEM);
 349                         sl = (struct slcompress *)resp->data;
 350                         *sl = *sl0;
 351
 352                         /* Replace pointers with integer indicies */
 353                         if (sl->last_cs != NULL) {
 354                                 index = sl0->last_cs - sl0->tstate;
 355                                 bzero(&sl->last_cs, sizeof(sl->last_cs));
 356                                 *((u_int16_t *)&sl->last_cs) = index;
 357                         }
 358                         for (i = 0; i < MAX_STATES; i++) {
 359                                 struct cstate *const cs = &sl->tstate[i];
 360
 361                                 index = sl0->tstate[i].cs_next - sl0->tstate;
 362                                 bzero(&cs->cs_next, sizeof(cs->cs_next));
 363                                 *((u_int16_t *)&cs->cs_next) = index;
 364                         }
 365                         break;
 366                     }
 367                 case NGM_VJC_CLR_STATS:
 368                         priv->slc.sls_packets = 0;
 369                         priv->slc.sls_compressed = 0;
 370                         priv->slc.sls_searches = 0;
 371                         priv->slc.sls_misses = 0;
 372                         priv->slc.sls_uncompressedin = 0;
 373                         priv->slc.sls_compressedin = 0;
 374                         priv->slc.sls_errorin = 0;
 375                         priv->slc.sls_tossed = 0;
 376                         break;
 377                 case NGM_VJC_RECV_ERROR:
 378                         sl_uncompress_tcp(NULL, 0, TYPE_ERROR, &priv->slc);
 379                         break;
 380                 default:
 381                         error = EINVAL;
 382                         break;
 383                 }
 384                 break;
 385         default:
 386                 error = EINVAL;
 387                 break;
 388         }
 389 done:
 390         NG_RESPOND_MSG(error, node, item, resp);
 391         NG_FREE_MSG(msg);
 392         return (error);
 393 }
 394
 395 /*
 396  * Receive data
 397  */
 398 static int
 399 ng_vjc_rcvdata(hook_p hook, item_p item)
 400 {
 401         const node_p node = NG_HOOK_NODE(hook);
 402         const priv_p priv = NG_NODE_PRIVATE(node);
 403         int error = 0;
 404         struct mbuf *m;
 405
 406         NGI_GET_M(item, m);
 407         if (hook == priv->ip) {                 /* outgoing packet */
 408                 u_int type = TYPE_IP;
 409
 410                 /* Compress packet if enabled and proto is TCP */
 411                 if (priv->conf.enableComp) {
 412                         struct ip *ip;
 413
 414                         if ((m = ng_vjc_pulluphdrs(m, 0)) == NULL) {
 415                                 NG_FREE_ITEM(item);
 416                                 return (ENOBUFS);
 417                         }
 418                         ip = mtod(m, struct ip *);
 419                         if (ip->ip_p == IPPROTO_TCP) {
 420                                 const int origLen = m->m_len;
 421
 422                                 type = sl_compress_tcp(m, ip,
 423                                     &priv->slc, priv->conf.compressCID);
 424                                 m->m_pkthdr.len += m->m_len - origLen;
 425                         }
 426                 }
 427
 428                 /* Dispatch to the appropriate outgoing hook */
 429                 switch (type) {
 430                 case TYPE_IP:
 431                         hook = priv->vjip;
 432                         break;
 433                 case TYPE_UNCOMPRESSED_TCP:
 434                         hook = priv->vjuncomp;
 435                         break;
 436                 case TYPE_COMPRESSED_TCP:
 437                         hook = priv->vjcomp;
 438                         break;
 439                 default:
 440                         panic("%s: type=%d", __func__, type);
 441                 }
 442         } else if (hook == priv->vjcomp) {      /* incoming compressed packet */
 443                 int vjlen, need2pullup;
 444                 struct mbuf *hm;
 445                 u_char *hdr;
 446                 u_int hlen;
 447
 448                 /* Are we decompressing? */
 449                 if (!priv->conf.enableDecomp) {
 450                         NG_FREE_M(m);
 451                         NG_FREE_ITEM(item);
 452                         return (ENXIO);
 453                 }
 454
 455                 /* Pull up the necessary amount from the mbuf */
 456                 need2pullup = MAX_VJHEADER;
 457                 if (need2pullup > m->m_pkthdr.len)
 458                         need2pullup = m->m_pkthdr.len;
 459                 if (m->m_len < need2pullup
 460                     && (m = m_pullup(m, need2pullup)) == NULL) {
 461                         priv->slc.sls_errorin++;
 462                         NG_FREE_ITEM(item);
 463                         return (ENOBUFS);
 464                 }
 465
 466                 /* Uncompress packet to reconstruct TCP/IP header */
 467                 vjlen = sl_uncompress_tcp_core(mtod(m, u_char *),
 468                     m->m_len, m->m_pkthdr.len, TYPE_COMPRESSED_TCP,
 469                     &priv->slc, &hdr, &hlen);
 470                 if (vjlen <= 0) {
 471                         NG_FREE_M(m);
 472                         NG_FREE_ITEM(item);
 473                         return (EINVAL);
 474                 }
 475                 m_adj(m, vjlen);
 476
 477                 /* Copy the reconstructed TCP/IP headers into a new mbuf */
 478                 MGETHDR(hm, M_DONTWAIT, MT_DATA);
 479                 if (hm == NULL) {
 480                         priv->slc.sls_errorin++;
 481                         NG_FREE_M(m);
 482                         NG_FREE_ITEM(item);
 483                         return (ENOBUFS);
 484                 }
 485                 hm->m_len = 0;
 486                 hm->m_pkthdr.rcvif = NULL;
 487                 if (hlen > MHLEN) {             /* unlikely, but can happen */
 488                         MCLGET(hm, M_DONTWAIT);
 489                         if ((hm->m_flags & M_EXT) == 0) {
 490                                 m_freem(hm);
 491                                 priv->slc.sls_errorin++;
 492                                 NG_FREE_M(m);
 493                                 NG_FREE_ITEM(item);
 494                                 return (ENOBUFS);
 495                         }
 496                 }
 497                 bcopy(hdr, mtod(hm, u_char *), hlen);
 498                 hm->m_len = hlen;
 499
 500                 /* Glue TCP/IP headers and rest of packet together */
 501                 hm->m_next = m;
 502                 hm->m_pkthdr.len = hlen + m->m_pkthdr.len;
 503                 m = hm;
 504                 hook = priv->ip;
 505         } else if (hook == priv->vjuncomp) {    /* incoming uncompressed pkt */
 506                 u_char *hdr;
 507                 u_int hlen;
 508
 509                 /* Are we decompressing? */
 510                 if (!priv->conf.enableDecomp) {
 511                         NG_FREE_M(m);
 512                         NG_FREE_ITEM(item);
 513                         return (ENXIO);
 514                 }
 515
 516                 /* Pull up IP+TCP headers */
 517                 if ((m = ng_vjc_pulluphdrs(m, 1)) == NULL) {
 518                         NG_FREE_ITEM(item);
 519                         return (ENOBUFS);
 520                 }
 521
 522                 /* Run packet through uncompressor */
 523                 if (sl_uncompress_tcp_core(mtod(m, u_char *),
 524                     m->m_len, m->m_pkthdr.len, TYPE_UNCOMPRESSED_TCP,
 525                     &priv->slc, &hdr, &hlen) < 0) {
 526                         NG_FREE_M(m);
 527                         NG_FREE_ITEM(item);
 528                         return (EINVAL);
 529                 }
 530                 hook = priv->ip;
 531         } else if (hook == priv->vjip)  /* incoming regular packet (bypass) */
 532                 hook = priv->ip;
 533         else
 534                 panic("%s: unknown hook", __func__);
 535
 536         /* Send result back out */
 537         NG_FWD_NEW_DATA(error, item, hook, m);
 538         return (error);
 539 }
 540
 541 /*
 542  * Shutdown node
 543  */
 544 static int
 545 ng_vjc_shutdown(node_p node)
 546 {
 547         const priv_p priv = NG_NODE_PRIVATE(node);
 548
 549         bzero(priv, sizeof(*priv));
 550         FREE(priv, M_NETGRAPH);
 551         NG_NODE_SET_PRIVATE(node, NULL);
 552         NG_NODE_UNREF(node);
 553         return (0);
 554 }
 555
 556 /*
 557  * Hook disconnection
 558  */
 559 static int
 560 ng_vjc_disconnect(hook_p hook)
 561 {
 562         const node_p node = NG_HOOK_NODE(hook);
 563         const priv_p priv = NG_NODE_PRIVATE(node);
 564
 565         /* Zero out hook pointer */
 566         if (hook == priv->ip)
 567                 priv->ip = NULL;
 568         else if (hook == priv->vjcomp)
 569                 priv->vjcomp = NULL;
 570         else if (hook == priv->vjuncomp)
 571                 priv->vjuncomp = NULL;
 572         else if (hook == priv->vjip)
 573                 priv->vjip = NULL;
 574         else
 575                 panic("%s: unknown hook", __func__);
 576
 577         /* Go away if no hooks left */
 578         if ((NG_NODE_NUMHOOKS(node) == 0)
 579         && (NG_NODE_IS_VALID(node)))
 580                 ng_rmnode_self(node);
 581         return (0);
 582 }
 583
 584 /************************************************************************
 585                         HELPER STUFF
 586  ************************************************************************/
 587
 588 /*
 589  * Pull up the full IP and TCP headers of a packet. If packet is not
 590  * a TCP packet, just pull up the IP header.
 591  */
 592 static struct mbuf *
 593 ng_vjc_pulluphdrs(struct mbuf *m, int knownTCP)
 594 {
 595         struct ip *ip;
 596         struct tcphdr *tcp;
 597         int ihlen, thlen;
 598
 599         if (m->m_len < sizeof(*ip) && (m = m_pullup(m, sizeof(*ip))) == NULL)
 600                 return (NULL);
 601         ip = mtod(m, struct ip *);
 602         if (!knownTCP && ip->ip_p != IPPROTO_TCP)
 603                 return (m);
 604         ihlen = ip->ip_hl << 2;
 605         if (m->m_len < ihlen + sizeof(*tcp)) {
 606                 if ((m = m_pullup(m, ihlen + sizeof(*tcp))) == NULL)
 607                         return (NULL);
 608                 ip = mtod(m, struct ip *);
 609         }
 610         tcp = (struct tcphdr *)((u_char *)ip + ihlen);
 611         thlen = tcp->th_off << 2;
 612         if (m->m_len < ihlen + thlen)
 613                 m = m_pullup(m, ihlen + thlen);
 614         return (m);
 615 }
 616