alias/alias_nbt.c

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*-
  24  * Written by Atsushi Murai <amurai@spec.co.jp>
  25  * Copyright (c) 1998, System Planning and Engineering Co.
  26  * All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Redistributions in binary form must reproduce the above copyright
  34  *    notice, this list of conditions and the following disclaimer in the
  35  *    documentation and/or other materials provided with the distribution.
  36  *
  37  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  38  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  39  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  40  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  41  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  42  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  43  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  45  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  46  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  47  * SUCH DAMAGE.
  48  *
  49  * Based upon:
  50  * $FreeBSD: src/lib/libalias/alias_nbt.c,v 1.4.2.3 2001/08/01 09:52:26 obrien Exp $
  51  *
  52  *  TODO:
  53  *       oClean up.
  54  *       oConsidering for word alignment for other platform.
  55  */
  56 /*
  57     alias_nbt.c performs special processing for NetBios over TCP/IP
  58     sessions by UDP.
  59
  60     Initial version:  May, 1998  (Atsushi Murai <amurai@spec.co.jp>)
  61
  62     See HISTORY file for record of revisions.
  63 */
  64
  65 /* Includes */
  66 #include <ctype.h>
  67 #include <stdio.h>
  68 #include <string.h>
  69 #include <sys/types.h>
  70 #include <netinet/in_systm.h>
  71 #include <netinet/in.h>
  72 #include <arpa/inet.h>
  73 #include <netinet/ip.h>
  74 #include <netinet/udp.h>
  75 #include <netinet/tcp.h>
  76
  77 #include "alias_local.h"
  78
  79 typedef struct {
  80         struct in_addr          oldaddr;
  81         u_short                         oldport;
  82         struct in_addr          newaddr;
  83         u_short                         newport;
  84         u_short                         *uh_sum;
  85 } NBTArguments;
  86
  87 typedef struct {
  88         unsigned char   type;
  89         unsigned char   flags;
  90         u_short                 id;
  91         struct in_addr  source_ip;
  92         u_short                 source_port;
  93         u_short                 len;
  94         u_short                 offset;
  95 } NbtDataHeader;
  96
  97 #define OpQuery         0
  98 #define OpUnknown       4
  99 #define OpRegist        5
 100 #define OpRelease       6
 101 #define OpWACK          7
 102 #define OpRefresh       8
 103 typedef struct {
 104         u_short                 nametrid;
 105         u_short                 dir:1, opcode:4, nmflags:7, rcode:4;
 106         u_short                 qdcount;
 107         u_short                 ancount;
 108         u_short                 nscount;
 109         u_short                 arcount;
 110 } NbtNSHeader;
 111
 112 #define FMT_ERR         0x1
 113 #define SRV_ERR         0x2
 114 #define IMP_ERR         0x4
 115 #define RFS_ERR         0x5
 116 #define ACT_ERR         0x6
 117 #define CFT_ERR         0x7
 118
 119
 120 #ifdef DEBUG
 121 static void PrintRcode( u_char rcode )  {
 122
 123         switch (rcode) {
 124                 case FMT_ERR:
 125                         printf("\nFormat Error.");
 126                 case SRV_ERR:
 127                         printf("\nSever failure.");
 128                 case IMP_ERR:
 129                         printf("\nUnsupported request error.\n");
 130                 case RFS_ERR:
 131                         printf("\nRefused error.\n");
 132                 case ACT_ERR:
 133                         printf("\nActive error.\n");
 134                 case CFT_ERR:
 135                         printf("\nName in conflict error.\n");
 136                 default:
 137                         printf("\n???=%0x\n", rcode );
 138
 139         }
 140 }
 141 #endif
 142
 143
 144 /* Handling Name field */
 145 static u_char *AliasHandleName ( u_char *p, char *pmax ) {
 146
 147         u_char *s;
 148         u_char c;
 149         int             compress;
 150
 151         /* Following length field */
 152
 153         if (p == NULL || (char *)p >= pmax)
 154                 return(NULL);
 155
 156         if (*p & 0xc0 ) {
 157                 p = p + 2;
 158                 if ((char *)p > pmax)
 159                         return(NULL);
 160                 return ((u_char *)p);
 161         }
 162         while ( ( *p & 0x3f) != 0x00 ) {
 163                 s = p + 1;
 164                 if ( *p == 0x20 )
 165                         compress = 1;
 166                 else
 167                         compress = 0;
 168
 169                 /* Get next length field */
 170                 p = (u_char *)(p + (*p & 0x3f) + 1);
 171                 if ((char *)p > pmax) {
 172                         p = NULL;
 173                         break;
 174                 }
 175 #ifdef DEBUG
 176                 printf(":");
 177 #endif
 178                 while (s < p) {
 179                         if ( compress == 1 ) {
 180                                 c = (u_char )(((((*s & 0x0f) << 4) | (*(s+1) & 0x0f)) - 0x11));
 181 #ifdef DEBUG
 182                                 if (isprint( c ) )
 183                                         printf("%c", c );
 184                                 else
 185                                         printf("<0x%02x>", c );
 186 #endif
 187                                 s +=2;
 188                         } else {
 189 #ifdef DEBUG
 190                                 printf("%c", *s);
 191 #endif
 192                                 s++;
 193                         }
 194                 }
 195 #ifdef DEBUG
 196                 printf(":");
 197 #endif
 198                 fflush(stdout);
 199     }
 200
 201         /* Set up to out of Name field */
 202         if (p == NULL || (char *)p >= pmax)
 203             p = NULL;
 204         else
 205             p++;
 206         return ((u_char *)p);
 207 }
 208
 209 /*
 210  * NetBios Datagram Handler (IP/UDP)
 211  */
 212 #define DGM_DIRECT_UNIQ         0x10
 213 #define DGM_DIRECT_GROUP        0x11
 214 #define DGM_BROADCAST           0x12
 215 #define DGM_ERROR                       0x13
 216 #define DGM_QUERY                       0x14
 217 #define DGM_POSITIVE_RES        0x15
 218 #define DGM_NEGATIVE_RES        0x16
 219
 220 int AliasHandleUdpNbt(
 221         struct ip                       *pip,    /* IP packet to examine/patch */
 222         struct alias_link       *link,
 223         struct in_addr          *alias_address,
 224     u_short             alias_port
 225 ) {
 226     struct udphdr *     uh;
 227     NbtDataHeader       *ndh;
 228     u_char              *p = NULL;
 229     char                *pmax;
 230
 231     /* Calculate data length of UDP packet */
 232     uh =  (struct udphdr *) ((char *) pip + (pip->ip_hl << 2));
 233     pmax = (char *)uh + ntohs( uh->uh_ulen );
 234
 235         ndh = (NbtDataHeader *)((char *)uh + (sizeof (struct udphdr)));
 236     if ((char *)(ndh + 1) > pmax)
 237             return(-1);
 238 #ifdef DEBUG
 239         printf("\nType=%02x,", ndh->type );
 240 #endif
 241         switch ( ndh->type ) {
 242                 case DGM_DIRECT_UNIQ:
 243                 case DGM_DIRECT_GROUP:
 244                 case DGM_BROADCAST:
 245                         p = (u_char *)ndh + 14;
 246                     p = AliasHandleName ( p, pmax ); /* Source Name */
 247                     p = AliasHandleName ( p, pmax ); /* Destination Name */
 248                         break;
 249                 case DGM_ERROR:
 250                         p = (u_char *)ndh + 11;
 251                         break;
 252                 case DGM_QUERY:
 253                 case DGM_POSITIVE_RES:
 254                 case DGM_NEGATIVE_RES:
 255                         p = (u_char *)ndh + 10;
 256                     p = AliasHandleName ( p, pmax ); /* Destination Name */
 257                         break;
 258         }
 259     if (p == NULL || (char *)p > pmax)
 260             p = NULL;
 261 #ifdef DEBUG
 262         printf("%s:%d-->", inet_ntoa(ndh->source_ip), ntohs(ndh->source_port) );
 263 #endif
 264         /* Doing a IP address and Port number Translation */
 265         if ( uh->uh_sum != 0 ) {
 266                 int                             acc;
 267                 u_short                 *sptr;
 268                 acc  = ndh->source_port;
 269                 acc -= alias_port;
 270                 sptr = (u_short *) &(ndh->source_ip);
 271                 acc += *sptr++;
 272                 acc += *sptr;
 273                 sptr = (u_short *) alias_address;
 274                 acc -= *sptr++;
 275                 acc -= *sptr;
 276                 ADJUST_CHECKSUM(acc, uh->uh_sum);
 277         }
 278     ndh->source_ip = *alias_address;
 279     ndh->source_port = alias_port;
 280 #ifdef DEBUG
 281         printf("%s:%d\n", inet_ntoa(ndh->source_ip), ntohs(ndh->source_port) );
 282         fflush(stdout);
 283 #endif
 284     return((p == NULL) ? -1 : 0);
 285 }
 286 /* Question Section */
 287 #define QS_TYPE_NB              0x0020
 288 #define QS_TYPE_NBSTAT  0x0021
 289 #define QS_CLAS_IN              0x0001
 290 typedef struct {
 291         u_short type;   /* The type of Request */
 292         u_short class;  /* The class of Request */
 293 } NBTNsQuestion;
 294
 295 static u_char *
 296 AliasHandleQuestion(
 297     u_short count,
 298                                                         NBTNsQuestion *q,
 299     char *pmax,
 300                                                         NBTArguments  *nbtarg)
 301 {
 302
 303         while ( count != 0 ) {
 304                 /* Name Filed */
 305                 q = (NBTNsQuestion *)AliasHandleName((u_char *)q, pmax);
 306
 307                 if (q == NULL || (char *)(q + 1) > pmax) {
 308                         q = NULL;
 309                         break;
 310                 }
 311
 312                 /* Type and Class filed */
 313                 switch ( ntohs(q->type) ) {
 314                         case QS_TYPE_NB:
 315                         case QS_TYPE_NBSTAT:
 316                                 q= q+1;
 317                         break;
 318                         default:
 319 #ifdef DEBUG
 320                                 printf("\nUnknown Type on Question %0x\n", ntohs(q->type) );
 321 #endif
 322                         break;
 323                 }
 324                 count--;
 325         }
 326
 327         /* Set up to out of Question Section */
 328         return ((u_char *)q);
 329 }
 330
 331 /* Resource Record */
 332 #define RR_TYPE_A               0x0001
 333 #define RR_TYPE_NS              0x0002
 334 #define RR_TYPE_NULL    0x000a
 335 #define RR_TYPE_NB              0x0020
 336 #define RR_TYPE_NBSTAT  0x0021
 337 #define RR_CLAS_IN              0x0001
 338 #define SizeOfNsResource        8
 339 typedef struct {
 340         u_short type;
 341         u_short class;
 342         unsigned int ttl;
 343         u_short rdlen;
 344 } NBTNsResource;
 345
 346 #define SizeOfNsRNB                     6
 347 typedef struct {
 348         u_short g:1, ont:2, resv:13;
 349         struct  in_addr addr;
 350 } NBTNsRNB;
 351
 352 static u_char *
 353 AliasHandleResourceNB(
 354     NBTNsResource *q,
 355     char *pmax,
 356                                                            NBTArguments  *nbtarg)
 357 {
 358         NBTNsRNB        *nb;
 359         u_short bcount;
 360
 361         if (q == NULL || (char *)(q + 1) > pmax)
 362                 return(NULL);
 363         /* Check out a length */
 364         bcount = ntohs(q->rdlen);
 365
 366         /* Forward to Resource NB position */
 367         nb = (NBTNsRNB *)((u_char *)q + SizeOfNsResource);
 368
 369         /* Processing all in_addr array */
 370 #ifdef DEBUG
 371         printf("NB rec[%s", inet_ntoa(nbtarg->oldaddr));
 372             printf("->%s, %dbytes] ",inet_ntoa(nbtarg->newaddr ), bcount);
 373 #endif
 374         while ( nb != NULL && bcount != 0 )  {
 375                 if ((char *)(nb + 1) > pmax) {
 376                         nb = NULL;
 377                         break;
 378                 }
 379 #ifdef DEBUG
 380                 printf("<%s>", inet_ntoa(nb->addr) );
 381 #endif
 382                 if (!bcmp(&nbtarg->oldaddr,&nb->addr, sizeof(struct in_addr) ) ) {
 383                         if ( *nbtarg->uh_sum != 0 ) {
 384                 int acc;
 385                 u_short *sptr;
 386
 387                 sptr = (u_short *) &(nb->addr);
 388                 acc = *sptr++;
 389                 acc += *sptr;
 390                 sptr = (u_short *) &(nbtarg->newaddr);
 391                 acc -= *sptr++;
 392                 acc -= *sptr;
 393                 ADJUST_CHECKSUM(acc, *nbtarg->uh_sum);
 394                         }
 395
 396                         nb->addr = nbtarg->newaddr;
 397 #ifdef DEBUG
 398                         printf("O");
 399 #endif
 400                 }
 401 #ifdef DEBUG
 402                  else {
 403                         printf(".");
 404                 }
 405 #endif
 406                 nb=(NBTNsRNB *)((u_char *)nb + SizeOfNsRNB);
 407                 bcount -= SizeOfNsRNB;
 408         }
 409         if (nb == NULL || (char *)(nb + 1) > pmax) {
 410                 nb = NULL;
 411         }
 412
 413         return ((u_char *)nb);
 414 }
 415
 416 #define SizeOfResourceA         6
 417 typedef struct {
 418         struct  in_addr addr;
 419 } NBTNsResourceA;
 420
 421 static u_char *
 422 AliasHandleResourceA(
 423     NBTNsResource *q,
 424     char *pmax,
 425                                                           NBTArguments  *nbtarg)
 426 {
 427         NBTNsResourceA  *a;
 428         u_short bcount;
 429
 430         if (q == NULL || (char *)(q + 1) > pmax)
 431                 return(NULL);
 432
 433         /* Forward to Resource A position */
 434         a = (NBTNsResourceA *)( (u_char *)q + sizeof(NBTNsResource) );
 435
 436         /* Check out of length */
 437         bcount = ntohs(q->rdlen);
 438
 439         /* Processing all in_addr array */
 440 #ifdef DEBUG
 441         printf("Arec [%s", inet_ntoa(nbtarg->oldaddr));
 442         printf("->%s]",inet_ntoa(nbtarg->newaddr ));
 443 #endif
 444         while ( bcount != 0 )  {
 445                 if (a == NULL || (char *)(a + 1) > pmax)
 446                         return(NULL);
 447 #ifdef DEBUG
 448                 printf("..%s", inet_ntoa(a->addr) );
 449 #endif
 450                 if ( !bcmp(&nbtarg->oldaddr, &a->addr, sizeof(struct in_addr) ) ) {
 451                         if ( *nbtarg->uh_sum != 0 ) {
 452                 int acc;
 453                 u_short *sptr;
 454
 455                 sptr = (u_short *) &(a->addr);           /* Old */
 456                 acc = *sptr++;
 457                 acc += *sptr;
 458                 sptr = (u_short *) &nbtarg->newaddr; /* New */
 459                 acc -= *sptr++;
 460                 acc -= *sptr;
 461                 ADJUST_CHECKSUM(acc, *nbtarg->uh_sum);
 462                         }
 463
 464                         a->addr = nbtarg->newaddr;
 465                 }
 466                 a++;    /*XXXX*/
 467                 bcount -= SizeOfResourceA;
 468         }
 469         if (a == NULL || (char *)(a + 1) > pmax)
 470                 a =  NULL;
 471         return ((u_char *)a);
 472 }
 473
 474 typedef struct {
 475         u_short opcode:4, flags:8, resv:4;
 476 } NBTNsResourceNULL;
 477
 478 static u_char *
 479 AliasHandleResourceNULL(
 480     NBTNsResource *q,
 481     char *pmax,
 482                                                              NBTArguments  *nbtarg)
 483 {
 484         NBTNsResourceNULL       *n;
 485         u_short bcount;
 486
 487         if (q == NULL || (char *)(q + 1) > pmax)
 488                 return(NULL);
 489
 490         /* Forward to Resource NULL position */
 491         n = (NBTNsResourceNULL *)( (u_char *)q + sizeof(NBTNsResource) );
 492
 493         /* Check out of length */
 494         bcount = ntohs(q->rdlen);
 495
 496         /* Processing all in_addr array */
 497         while ( bcount != 0 )  {
 498                 if ((char *)(n + 1) > pmax) {
 499                         n = NULL;
 500                         break;
 501                 }
 502                 n++;
 503                 bcount -= sizeof(NBTNsResourceNULL);
 504         }
 505         if ((char *)(n + 1) > pmax)
 506                 n = NULL;
 507
 508         return ((u_char *)n);
 509 }
 510
 511 static u_char *
 512 AliasHandleResourceNS(
 513     NBTNsResource *q,
 514     char *pmax,
 515                                                              NBTArguments  *nbtarg)
 516 {
 517         NBTNsResourceNULL       *n;
 518         u_short bcount;
 519
 520         if (q == NULL || (char *)(q + 1) > pmax)
 521                 return(NULL);
 522
 523         /* Forward to Resource NULL position */
 524         n = (NBTNsResourceNULL *)( (u_char *)q + sizeof(NBTNsResource) );
 525
 526         /* Check out of length */
 527         bcount = ntohs(q->rdlen);
 528
 529         /* Resource Record Name Filed */
 530         q = (NBTNsResource *)AliasHandleName( (u_char *)n, pmax ); /* XXX */
 531
 532         if (q == NULL || (char *)((u_char *)n + bcount) > pmax)
 533                 return(NULL);
 534         else
 535         return ((u_char *)n + bcount);
 536 }
 537
 538 typedef struct {
 539         u_short numnames;
 540 } NBTNsResourceNBSTAT;
 541
 542 static u_char *
 543 AliasHandleResourceNBSTAT(
 544     NBTNsResource *q,
 545     char *pmax,
 546                                                                NBTArguments  *nbtarg)
 547 {
 548         NBTNsResourceNBSTAT     *n;
 549         u_short bcount;
 550
 551         if (q == NULL || (char *)(q + 1) > pmax)
 552                 return(NULL);
 553
 554         /* Forward to Resource NBSTAT position */
 555         n = (NBTNsResourceNBSTAT *)( (u_char *)q + sizeof(NBTNsResource) );
 556
 557         /* Check out of length */
 558         bcount = ntohs(q->rdlen);
 559
 560         if (q == NULL || (char *)((u_char *)n + bcount) > pmax)
 561                 return(NULL);
 562         else
 563         return ((u_char *)n + bcount);
 564 }
 565
 566 static u_char *
 567 AliasHandleResource(
 568     u_short count,
 569                                                         NBTNsResource *q,
 570     char *pmax,
 571     NBTArguments
 572     *nbtarg)
 573 {
 574         while ( count != 0 ) {
 575                 /* Resource Record Name Filed */
 576                 q = (NBTNsResource *)AliasHandleName( (u_char *)q, pmax );
 577
 578                 if (q == NULL || (char *)(q + 1) > pmax)
 579                         break;
 580 #ifdef DEBUG
 581                 printf("type=%02x, count=%d\n", ntohs(q->type), count );
 582 #endif
 583
 584                 /* Type and Class filed */
 585                 switch ( ntohs(q->type) ) {
 586                         case RR_TYPE_NB:
 587                                 q = (NBTNsResource *)AliasHandleResourceNB(
 588                                     q,
 589                                     pmax,
 590                                     nbtarg
 591                                 );
 592                                 break;
 593                         case RR_TYPE_A:
 594                                 q = (NBTNsResource *)AliasHandleResourceA(
 595                                     q,
 596                                     pmax,
 597                                     nbtarg
 598                                 );
 599                                 break;
 600                         case RR_TYPE_NS:
 601                                 q = (NBTNsResource *)AliasHandleResourceNS(
 602                                     q,
 603                                     pmax,
 604                                     nbtarg
 605                                 );
 606                                 break;
 607                         case RR_TYPE_NULL:
 608                                 q = (NBTNsResource *)AliasHandleResourceNULL(
 609                                     q,
 610                                     pmax,
 611                                     nbtarg
 612                                 );
 613                                 break;
 614                         case RR_TYPE_NBSTAT:
 615                                 q = (NBTNsResource *)AliasHandleResourceNBSTAT(
 616                                     q,
 617                                     pmax,
 618                                     nbtarg
 619                                 );
 620                                 break;
 621                         default:
 622 #ifdef DEBUG
 623                                 printf(
 624                                     "\nUnknown Type of Resource %0x\n",
 625                                     ntohs(q->type)
 626                                 );
 627 #endif
 628                                 break;
 629                 }
 630                 count--;
 631         }
 632         fflush(stdout);
 633         return ((u_char *)q);
 634 }
 635
 636 int AliasHandleUdpNbtNS(
 637         struct ip                       *pip,    /* IP packet to examine/patch */
 638         struct alias_link       *link,
 639         struct in_addr          *alias_address,
 640         u_short                         *alias_port,
 641         struct in_addr          *original_address,
 642         u_short                         *original_port )
 643 {
 644     struct udphdr *     uh;
 645         NbtNSHeader       * nsh;
 646         u_char            * p;
 647         char            *pmax;
 648         NBTArguments    nbtarg;
 649
 650         /* Set up Common Parameter */
 651         nbtarg.oldaddr  =       *alias_address;
 652         nbtarg.oldport  =       *alias_port;
 653         nbtarg.newaddr  =       *original_address;
 654         nbtarg.newport  =       *original_port;
 655
 656     /* Calculate data length of UDP packet */
 657     uh =  (struct udphdr *) ((char *) pip + (pip->ip_hl << 2));
 658         nbtarg.uh_sum   =       &(uh->uh_sum);
 659         nsh = (NbtNSHeader *)((char *)uh + (sizeof(struct udphdr)));
 660         p = (u_char *)(nsh + 1);
 661     pmax = (char *)uh + ntohs( uh->uh_ulen );
 662
 663     if ((char *)(nsh + 1) > pmax)
 664         return(-1);
 665
 666 #ifdef DEBUG
 667     printf(" [%s] ID=%02x, op=%01x, flag=%02x, rcode=%01x, qd=%04x"
 668            ", an=%04x, ns=%04x, ar=%04x, [%d]-->",
 669                 nsh->dir ? "Response": "Request",
 670                 nsh->nametrid,
 671                 nsh->opcode,
 672                 nsh->nmflags,
 673                 nsh->rcode,
 674                 ntohs(nsh->qdcount),
 675                 ntohs(nsh->ancount),
 676                 ntohs(nsh->nscount),
 677                 ntohs(nsh->arcount),
 678         (u_char *)p -(u_char *)nsh
 679     );
 680 #endif
 681
 682         /* Question Entries */
 683         if (ntohs(nsh->qdcount) !=0 ) {
 684         p = AliasHandleQuestion(
 685             ntohs(nsh->qdcount),
 686             (NBTNsQuestion *)p,
 687             pmax,
 688             &nbtarg
 689         );
 690         }
 691
 692         /* Answer Resource Records */
 693         if (ntohs(nsh->ancount) !=0 ) {
 694         p = AliasHandleResource(
 695             ntohs(nsh->ancount),
 696             (NBTNsResource *)p,
 697             pmax,
 698             &nbtarg
 699         );
 700         }
 701
 702         /* Authority Resource Recodrs */
 703         if (ntohs(nsh->nscount) !=0 ) {
 704         p = AliasHandleResource(
 705             ntohs(nsh->nscount),
 706             (NBTNsResource *)p,
 707             pmax,
 708             &nbtarg
 709         );
 710         }
 711
 712         /* Additional Resource Recodrs */
 713         if (ntohs(nsh->arcount) !=0 ) {
 714         p = AliasHandleResource(
 715             ntohs(nsh->arcount),
 716             (NBTNsResource *)p,
 717             pmax,
 718             &nbtarg
 719         );
 720         }
 721
 722 #ifdef DEBUG
 723                 PrintRcode(nsh->rcode);
 724 #endif
 725     return ((p == NULL) ? -1 : 0);
 726 }