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  * $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 #ifndef __LP64__
 113 #define NG_VJC_TSTATE_PTR_TYPE  &ng_parse_uint32_type
 114 #else
 115 #define NG_VJC_TSTATE_PTR_TYPE  &ng_parse_uint64_type
 116 #endif
 117
 118 /* Parse type for the 'cs_hdr' field in a struct cstate. Ideally we would
 119    like to use a 'struct ip' type instead of a simple array of bytes. */
 120 static const struct ng_parse_fixedarray_info ng_vjc_cs_hdr_type_info = {
 121         &ng_parse_hint8_type,
 122         MAX_HDR
 123 };
 124 static const struct ng_parse_type ng_vjc_cs_hdr_type = {
 125         &ng_parse_fixedarray_type,
 126         &ng_vjc_cs_hdr_type_info
 127 };
 128
 129 /* Parse type for a struct cstate */
 130 static const struct ng_parse_struct_field ng_vjc_cstate_type_fields[] = {
 131         { "cs_next",            NG_VJC_TSTATE_PTR_TYPE          },
 132         { "cs_hlen",            &ng_parse_uint16_type           },
 133         { "cs_id",              &ng_parse_uint8_type            },
 134         { "cs_filler",          &ng_parse_uint8_type            },
 135         { "cs_hdr",             &ng_vjc_cs_hdr_type             },
 136         { NULL }
 137 };
 138 static const struct ng_parse_type ng_vjc_cstate_type = {
 139         &ng_parse_struct_type,
 140         &ng_vjc_cstate_type_fields
 141 };
 142
 143 /* Parse type for an array of MAX_STATES struct cstate's, ie, tstate & rstate */
 144 static const struct ng_parse_fixedarray_info ng_vjc_cstatearray_type_info = {
 145         &ng_vjc_cstate_type,
 146         MAX_STATES
 147 };
 148 static const struct ng_parse_type ng_vjc_cstatearray_type = {
 149         &ng_parse_fixedarray_type,
 150         &ng_vjc_cstatearray_type_info
 151 };
 152
 153 /* Parse type for struct slcompress. Keep this in sync with the
 154    definition of struct slcompress defined in <net/slcompress.h> */
 155 static const struct ng_parse_struct_field ng_vjc_slcompress_type_fields[] = {
 156         { "last_cs",            NG_VJC_TSTATE_PTR_TYPE          },
 157         { "last_recv",          &ng_parse_uint8_type            },
 158         { "last_xmit",          &ng_parse_uint8_type            },
 159         { "flags",              &ng_parse_hint16_type           },
 160 #ifndef SL_NO_STATS
 161         { "sls_packets",        &ng_parse_uint32_type           },
 162         { "sls_compressed",     &ng_parse_uint32_type           },
 163         { "sls_searches",       &ng_parse_uint32_type           },
 164         { "sls_misses",         &ng_parse_uint32_type           },
 165         { "sls_uncompressedin", &ng_parse_uint32_type           },
 166         { "sls_compressedin",   &ng_parse_uint32_type           },
 167         { "sls_errorin",        &ng_parse_uint32_type           },
 168         { "sls_tossed",         &ng_parse_uint32_type           },
 169 #endif
 170         { "tstate",             &ng_vjc_cstatearray_type        },
 171         { "rstate",             &ng_vjc_cstatearray_type        },
 172         { NULL }
 173 };
 174 static const struct ng_parse_type ng_vjc_slcompress_type = {
 175         &ng_parse_struct_type,
 176         &ng_vjc_slcompress_type_fields
 177 };
 178
 179 /* List of commands and how to convert arguments to/from ASCII */
 180 static const struct ng_cmdlist ng_vjc_cmds[] = {
 181         {
 182           NGM_VJC_COOKIE,
 183           NGM_VJC_SET_CONFIG,
 184           "setconfig",
 185           &ng_vjc_config_type,
 186           NULL
 187         },
 188         {
 189           NGM_VJC_COOKIE,
 190           NGM_VJC_GET_CONFIG,
 191           "getconfig",
 192           NULL,
 193           &ng_vjc_config_type,
 194         },
 195         {
 196           NGM_VJC_COOKIE,
 197           NGM_VJC_GET_STATE,
 198           "getstate",
 199           NULL,
 200           &ng_vjc_slcompress_type,
 201         },
 202         {
 203           NGM_VJC_COOKIE,
 204           NGM_VJC_CLR_STATS,
 205           "clrstats",
 206           NULL,
 207           NULL,
 208         },
 209         {
 210           NGM_VJC_COOKIE,
 211           NGM_VJC_RECV_ERROR,
 212           "recverror",
 213           NULL,
 214           NULL,
 215         },
 216         { 0 }
 217 };
 218
 219 /* Node type descriptor */
 220 static struct ng_type ng_vjc_typestruct = {
 221         .version =      NG_ABI_VERSION,
 222         .name =         NG_VJC_NODE_TYPE,
 223         .constructor =  ng_vjc_constructor,
 224         .rcvmsg =       ng_vjc_rcvmsg,
 225         .shutdown =     ng_vjc_shutdown,
 226         .newhook =      ng_vjc_newhook,
 227         .rcvdata =      ng_vjc_rcvdata,
 228         .disconnect =   ng_vjc_disconnect,
 229         .cmdlist =      ng_vjc_cmds,
 230 };
 231 NETGRAPH_INIT(vjc, &ng_vjc_typestruct);
 232
 233 /************************************************************************
 234                         NETGRAPH NODE METHODS
 235  ************************************************************************/
 236
 237 /*
 238  * Create a new node
 239  */
 240 static int
 241 ng_vjc_constructor(node_p node)
 242 {
 243         priv_p priv;
 244
 245         /* Allocate private structure */
 246         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH, M_NOWAIT | M_ZERO);
 247         if (priv == NULL)
 248                 return (ENOMEM);
 249
 250         NG_NODE_SET_PRIVATE(node, priv);
 251
 252         /* Done */
 253         return (0);
 254 }
 255
 256 /*
 257  * Add a new hook
 258  */
 259 static int
 260 ng_vjc_newhook(node_p node, hook_p hook, const char *name)
 261 {
 262         const priv_p priv = NG_NODE_PRIVATE(node);
 263         hook_p *hookp;
 264
 265         /* Get hook */
 266         if (strcmp(name, NG_VJC_HOOK_IP) == 0)
 267                 hookp = &priv->ip;
 268         else if (strcmp(name, NG_VJC_HOOK_VJCOMP) == 0)
 269                 hookp = &priv->vjcomp;
 270         else if (strcmp(name, NG_VJC_HOOK_VJUNCOMP) == 0)
 271                 hookp = &priv->vjuncomp;
 272         else if (strcmp(name, NG_VJC_HOOK_VJIP) == 0)
 273                 hookp = &priv->vjip;
 274         else
 275                 return (EINVAL);
 276
 277         /* See if already connected */
 278         if (*hookp)
 279                 return (EISCONN);
 280
 281         /* OK */
 282         *hookp = hook;
 283         return (0);
 284 }
 285
 286 /*
 287  * Receive a control message
 288  */
 289 static int
 290 ng_vjc_rcvmsg(node_p node, item_p item, hook_p lasthook)
 291 {
 292         const priv_p priv = NG_NODE_PRIVATE(node);
 293         struct ng_mesg *resp = NULL;
 294         int error = 0;
 295         struct ng_mesg *msg;
 296
 297         NGI_GET_MSG(item, msg);
 298         /* Check type cookie */
 299         switch (msg->header.typecookie) {
 300         case NGM_VJC_COOKIE:
 301                 switch (msg->header.cmd) {
 302                 case NGM_VJC_SET_CONFIG:
 303                     {
 304                         struct ngm_vjc_config *const c =
 305                                 (struct ngm_vjc_config *) msg->data;
 306
 307                         if (msg->header.arglen != sizeof(*c))
 308                                 ERROUT(EINVAL);
 309                         if ((priv->conf.enableComp || priv->conf.enableDecomp)
 310                             && (c->enableComp || c->enableDecomp))
 311                                 ERROUT(EALREADY);
 312                         if (c->enableComp) {
 313                                 if (c->maxChannel > NG_VJC_MAX_CHANNELS - 1
 314                                     || c->maxChannel < NG_VJC_MIN_CHANNELS - 1)
 315                                         ERROUT(EINVAL);
 316                         } else
 317                                 c->maxChannel = NG_VJC_MAX_CHANNELS - 1;
 318                         if (c->enableComp != 0 || c->enableDecomp != 0) {
 319                                 bzero(&priv->slc, sizeof(priv->slc));
 320                                 sl_compress_init(&priv->slc, c->maxChannel);
 321                         }
 322                         priv->conf = *c;
 323                         break;
 324                     }
 325                 case NGM_VJC_GET_CONFIG:
 326                     {
 327                         struct ngm_vjc_config *conf;
 328
 329                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
 330                         if (resp == NULL)
 331                                 ERROUT(ENOMEM);
 332                         conf = (struct ngm_vjc_config *)resp->data;
 333                         *conf = priv->conf;
 334                         break;
 335                     }
 336                 case NGM_VJC_GET_STATE:
 337                     {
 338                         const struct slcompress *const sl0 = &priv->slc;
 339                         struct slcompress *sl;
 340                         u_int16_t index;
 341                         int i;
 342
 343                         /* Get response structure */
 344                         NG_MKRESPONSE(resp, msg, sizeof(*sl), M_NOWAIT);
 345                         if (resp == NULL)
 346                                 ERROUT(ENOMEM);
 347                         sl = (struct slcompress *)resp->data;
 348                         *sl = *sl0;
 349
 350                         /* Replace pointers with integer indicies */
 351                         if (sl->last_cs != NULL) {
 352                                 index = sl0->last_cs - sl0->tstate;
 353                                 bzero(&sl->last_cs, sizeof(sl->last_cs));
 354                                 *((u_int16_t *)&sl->last_cs) = index;
 355                         }
 356                         for (i = 0; i < MAX_STATES; i++) {
 357                                 struct cstate *const cs = &sl->tstate[i];
 358
 359                                 index = sl0->tstate[i].cs_next - sl0->tstate;
 360                                 bzero(&cs->cs_next, sizeof(cs->cs_next));
 361                                 *((u_int16_t *)&cs->cs_next) = index;
 362                         }
 363                         break;
 364                     }
 365                 case NGM_VJC_CLR_STATS:
 366                         priv->slc.sls_packets = 0;
 367                         priv->slc.sls_compressed = 0;
 368                         priv->slc.sls_searches = 0;
 369                         priv->slc.sls_misses = 0;
 370                         priv->slc.sls_uncompressedin = 0;
 371                         priv->slc.sls_compressedin = 0;
 372                         priv->slc.sls_errorin = 0;
 373                         priv->slc.sls_tossed = 0;
 374                         break;
 375                 case NGM_VJC_RECV_ERROR:
 376                         sl_uncompress_tcp(NULL, 0, TYPE_ERROR, &priv->slc);
 377                         break;
 378                 default:
 379                         error = EINVAL;
 380                         break;
 381                 }
 382                 break;
 383         default:
 384                 error = EINVAL;
 385                 break;
 386         }
 387 done:
 388         NG_RESPOND_MSG(error, node, item, resp);
 389         NG_FREE_MSG(msg);
 390         return (error);
 391 }
 392
 393 /*
 394  * Receive data
 395  */
 396 static int
 397 ng_vjc_rcvdata(hook_p hook, item_p item)
 398 {
 399         const node_p node = NG_HOOK_NODE(hook);
 400         const priv_p priv = NG_NODE_PRIVATE(node);
 401         int error = 0;
 402         struct mbuf *m;
 403
 404         NGI_GET_M(item, m);
 405         if (hook == priv->ip) {                 /* outgoing packet */
 406                 u_int type = TYPE_IP;
 407
 408                 /* Compress packet if enabled and proto is TCP */
 409                 if (priv->conf.enableComp) {
 410                         struct ip *ip;
 411
 412                         if ((m = ng_vjc_pulluphdrs(m, 0)) == NULL) {
 413                                 NG_FREE_ITEM(item);
 414                                 return (ENOBUFS);
 415                         }
 416                         ip = mtod(m, struct ip *);
 417                         if (ip->ip_p == IPPROTO_TCP) {
 418                                 const int origLen = m->m_len;
 419
 420                                 type = sl_compress_tcp(m, ip,
 421                                     &priv->slc, priv->conf.compressCID);
 422                                 m->m_pkthdr.len += m->m_len - origLen;
 423                         }
 424                 }
 425
 426                 /* Dispatch to the appropriate outgoing hook */
 427                 switch (type) {
 428                 case TYPE_IP:
 429                         hook = priv->vjip;
 430                         break;
 431                 case TYPE_UNCOMPRESSED_TCP:
 432                         hook = priv->vjuncomp;
 433                         break;
 434                 case TYPE_COMPRESSED_TCP:
 435                         hook = priv->vjcomp;
 436                         break;
 437                 default:
 438                         panic("%s: type=%d", __func__, type);
 439                 }
 440         } else if (hook == priv->vjcomp) {      /* incoming compressed packet */
 441                 int vjlen, need2pullup;
 442                 struct mbuf *hm;
 443                 u_char *hdr;
 444                 u_int hlen;
 445
 446                 /* Are we decompressing? */
 447                 if (!priv->conf.enableDecomp) {
 448                         NG_FREE_M(m);
 449                         NG_FREE_ITEM(item);
 450                         return (ENXIO);
 451                 }
 452
 453                 /* Pull up the necessary amount from the mbuf */
 454                 need2pullup = MAX_VJHEADER;
 455                 if (need2pullup > m->m_pkthdr.len)
 456                         need2pullup = m->m_pkthdr.len;
 457                 if (m->m_len < need2pullup
 458                     && (m = m_pullup(m, need2pullup)) == NULL) {
 459                         priv->slc.sls_errorin++;
 460                         NG_FREE_ITEM(item);
 461                         return (ENOBUFS);
 462                 }
 463
 464                 /* Uncompress packet to reconstruct TCP/IP header */
 465                 vjlen = sl_uncompress_tcp_core(mtod(m, u_char *),
 466                     m->m_len, m->m_pkthdr.len, TYPE_COMPRESSED_TCP,
 467                     &priv->slc, &hdr, &hlen);
 468                 if (vjlen <= 0) {
 469                         NG_FREE_M(m);
 470                         NG_FREE_ITEM(item);
 471                         return (EINVAL);
 472                 }
 473                 m_adj(m, vjlen);
 474
 475                 /* Copy the reconstructed TCP/IP headers into a new mbuf */
 476                 MGETHDR(hm, M_DONTWAIT, MT_DATA);
 477                 if (hm == NULL) {
 478                         priv->slc.sls_errorin++;
 479                         NG_FREE_M(m);
 480                         NG_FREE_ITEM(item);
 481                         return (ENOBUFS);
 482                 }
 483                 hm->m_len = 0;
 484                 hm->m_pkthdr.rcvif = NULL;
 485                 if (hlen > MHLEN) {             /* unlikely, but can happen */
 486                         MCLGET(hm, M_DONTWAIT);
 487                         if ((hm->m_flags & M_EXT) == 0) {
 488                                 m_freem(hm);
 489                                 priv->slc.sls_errorin++;
 490                                 NG_FREE_M(m);
 491                                 NG_FREE_ITEM(item);
 492                                 return (ENOBUFS);
 493                         }
 494                 }
 495                 bcopy(hdr, mtod(hm, u_char *), hlen);
 496                 hm->m_len = hlen;
 497
 498                 /* Glue TCP/IP headers and rest of packet together */
 499                 hm->m_next = m;
 500                 hm->m_pkthdr.len = hlen + m->m_pkthdr.len;
 501                 m = hm;
 502                 hook = priv->ip;
 503         } else if (hook == priv->vjuncomp) {    /* incoming uncompressed pkt */
 504                 u_char *hdr;
 505                 u_int hlen;
 506
 507                 /* Are we decompressing? */
 508                 if (!priv->conf.enableDecomp) {
 509                         NG_FREE_M(m);
 510                         NG_FREE_ITEM(item);
 511                         return (ENXIO);
 512                 }
 513
 514                 /* Pull up IP+TCP headers */
 515                 if ((m = ng_vjc_pulluphdrs(m, 1)) == NULL) {
 516                         NG_FREE_ITEM(item);
 517                         return (ENOBUFS);
 518                 }
 519
 520                 /* Run packet through uncompressor */
 521                 if (sl_uncompress_tcp_core(mtod(m, u_char *),
 522                     m->m_len, m->m_pkthdr.len, TYPE_UNCOMPRESSED_TCP,
 523                     &priv->slc, &hdr, &hlen) < 0) {
 524                         NG_FREE_M(m);
 525                         NG_FREE_ITEM(item);
 526                         return (EINVAL);
 527                 }
 528                 hook = priv->ip;
 529         } else if (hook == priv->vjip)  /* incoming regular packet (bypass) */
 530                 hook = priv->ip;
 531         else
 532                 panic("%s: unknown hook", __func__);
 533
 534         /* Send result back out */
 535         NG_FWD_NEW_DATA(error, item, hook, m);
 536         return (error);
 537 }
 538
 539 /*
 540  * Shutdown node
 541  */
 542 static int
 543 ng_vjc_shutdown(node_p node)
 544 {
 545         const priv_p priv = NG_NODE_PRIVATE(node);
 546
 547         bzero(priv, sizeof(*priv));
 548         FREE(priv, M_NETGRAPH);
 549         NG_NODE_SET_PRIVATE(node, NULL);
 550         NG_NODE_UNREF(node);
 551         return (0);
 552 }
 553
 554 /*
 555  * Hook disconnection
 556  */
 557 static int
 558 ng_vjc_disconnect(hook_p hook)
 559 {
 560         const node_p node = NG_HOOK_NODE(hook);
 561         const priv_p priv = NG_NODE_PRIVATE(node);
 562
 563         /* Zero out hook pointer */
 564         if (hook == priv->ip)
 565                 priv->ip = NULL;
 566         else if (hook == priv->vjcomp)
 567                 priv->vjcomp = NULL;
 568         else if (hook == priv->vjuncomp)
 569                 priv->vjuncomp = NULL;
 570         else if (hook == priv->vjip)
 571                 priv->vjip = NULL;
 572         else
 573                 panic("%s: unknown hook", __func__);
 574
 575         /* Go away if no hooks left */
 576         if ((NG_NODE_NUMHOOKS(node) == 0)
 577         && (NG_NODE_IS_VALID(node)))
 578                 ng_rmnode_self(node);
 579         return (0);
 580 }
 581
 582 /************************************************************************
 583                         HELPER STUFF
 584  ************************************************************************/
 585
 586 /*
 587  * Pull up the full IP and TCP headers of a packet. If packet is not
 588  * a TCP packet, just pull up the IP header.
 589  */
 590 static struct mbuf *
 591 ng_vjc_pulluphdrs(struct mbuf *m, int knownTCP)
 592 {
 593         struct ip *ip;
 594         struct tcphdr *tcp;
 595         int ihlen, thlen;
 596
 597         if (m->m_len < sizeof(*ip) && (m = m_pullup(m, sizeof(*ip))) == NULL)
 598                 return (NULL);
 599         ip = mtod(m, struct ip *);
 600         if (!knownTCP && ip->ip_p != IPPROTO_TCP)
 601                 return (m);
 602         ihlen = ip->ip_hl << 2;
 603         if (m->m_len < ihlen + sizeof(*tcp)) {
 604                 if ((m = m_pullup(m, ihlen + sizeof(*tcp))) == NULL)
 605                         return (NULL);
 606                 ip = mtod(m, struct ip *);
 607         }
 608         tcp = (struct tcphdr *)((u_char *)ip + ihlen);
 609         thlen = tcp->th_off << 2;
 610         if (m->m_len < ihlen + thlen)
 611                 m = m_pullup(m, ihlen + thlen);
 612         return (m);
 613 }
 614