lib/libalias/alias_nbt.c

   1 /*-
   2  * Written by Atsushi Murai <amurai@spec.co.jp>
   3  * Copyright (c) 1998, System Planning and Engineering Co.
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  * $FreeBSD: src/lib/libalias/alias_nbt.c,v 1.4.2.3 2001/08/01 09:52:26 obrien Exp $
  28  * $DragonFly: src/lib/libalias/alias_nbt.c,v 1.4 2006/03/18 20:43:18 swildner Exp $
  29  *
  30  *  TODO:
  31  *       oClean up.
  32  *       oConsidering for word alignment for other platform.
  33  */
  34 /*
  35     alias_nbt.c performs special processing for NetBios over TCP/IP
  36     sessions by UDP.
  37
  38     Initial version:  May, 1998  (Atsushi Murai <amurai@spec.co.jp>)
  39
  40     See HISTORY file for record of revisions.
  41 */
  42
  43 /* Includes */
  44 #include <sys/param.h>
  45 #include <ctype.h>
  46 #include <stdio.h>
  47 #include <string.h>
  48 #include <netinet/in_systm.h>
  49 #include <netinet/in.h>
  50 #include <arpa/inet.h>
  51 #include <netinet/ip.h>
  52 #include <netinet/udp.h>
  53 #include <netinet/tcp.h>
  54
  55 #include "alias_local.h"
  56
  57 typedef struct {
  58         struct in_addr          oldaddr;
  59         u_short                         oldport;
  60         struct in_addr          newaddr;
  61         u_short                         newport;
  62         u_short                         *uh_sum;
  63 } NBTArguments;
  64
  65 typedef struct {
  66         unsigned char   type;
  67         unsigned char   flags;
  68         u_short                 id;
  69         struct in_addr  source_ip;
  70         u_short                 source_port;
  71         u_short                 len;
  72         u_short                 offset;
  73 } NbtDataHeader;
  74
  75 #define OpQuery         0
  76 #define OpUnknown       4
  77 #define OpRegist        5
  78 #define OpRelease       6
  79 #define OpWACK          7
  80 #define OpRefresh       8
  81 typedef struct {
  82         u_short                 nametrid;
  83         u_short                 dir:1, opcode:4, nmflags:7, rcode:4;
  84         u_short                 qdcount;
  85         u_short                 ancount;
  86         u_short                 nscount;
  87         u_short                 arcount;
  88 } NbtNSHeader;
  89
  90 #define FMT_ERR         0x1
  91 #define SRV_ERR         0x2
  92 #define IMP_ERR         0x4
  93 #define RFS_ERR         0x5
  94 #define ACT_ERR         0x6
  95 #define CFT_ERR         0x7
  96
  97
  98 #ifdef DEBUG
  99 static void PrintRcode( u_char rcode )  {
 100
 101         switch (rcode) {
 102                 case FMT_ERR:
 103                         printf("\nFormat Error.");
 104                 case SRV_ERR:
 105                         printf("\nSever failure.");
 106                 case IMP_ERR:
 107                         printf("\nUnsupported request error.\n");
 108                 case RFS_ERR:
 109                         printf("\nRefused error.\n");
 110                 case ACT_ERR:
 111                         printf("\nActive error.\n");
 112                 case CFT_ERR:
 113                         printf("\nName in conflict error.\n");
 114                 default:
 115                         printf("\n??\?=%0x\n", rcode );
 116
 117         }
 118 }
 119 #endif
 120
 121
 122 /* Handling Name field */
 123 static u_char *AliasHandleName ( u_char *p, char *pmax ) {
 124
 125         u_char *s;
 126         u_char c;
 127         int             compress;
 128
 129         /* Following length field */
 130
 131         if (p == NULL || (char *)p >= pmax)
 132                 return(NULL);
 133
 134         if (*p & 0xc0 ) {
 135                 p = p + 2;
 136                 if ((char *)p > pmax)
 137                         return(NULL);
 138                 return ((u_char *)p);
 139         }
 140         while ( ( *p & 0x3f) != 0x00 ) {
 141                 s = p + 1;
 142                 if ( *p == 0x20 )
 143                         compress = 1;
 144                 else
 145                         compress = 0;
 146
 147                 /* Get next length field */
 148                 p = (u_char *)(p + (*p & 0x3f) + 1);
 149                 if ((char *)p > pmax) {
 150                         p = NULL;
 151                         break;
 152                 }
 153 #ifdef DEBUG
 154                 printf(":");
 155 #endif
 156                 while (s < p) {
 157                         if ( compress == 1 ) {
 158                                 c = (u_char )(((((*s & 0x0f) << 4) | (*(s+1) & 0x0f)) - 0x11));
 159 #ifdef DEBUG
 160                                 if (isprint( c ) )
 161                                         printf("%c", c );
 162                                 else
 163                                         printf("<0x%02x>", c );
 164 #endif
 165                                 s +=2;
 166                         } else {
 167 #ifdef DEBUG
 168                                 printf("%c", *s);
 169 #endif
 170                                 s++;
 171                         }
 172                 }
 173 #ifdef DEBUG
 174                 printf(":");
 175 #endif
 176                 fflush(stdout);
 177     }
 178
 179         /* Set up to out of Name field */
 180         if (p == NULL || (char *)p >= pmax)
 181             p = NULL;
 182         else
 183             p++;
 184         return ((u_char *)p);
 185 }
 186
 187 /*
 188  * NetBios Datagram Handler (IP/UDP)
 189  */
 190 #define DGM_DIRECT_UNIQ         0x10
 191 #define DGM_DIRECT_GROUP        0x11
 192 #define DGM_BROADCAST           0x12
 193 #define DGM_ERROR                       0x13
 194 #define DGM_QUERY                       0x14
 195 #define DGM_POSITIVE_RES        0x15
 196 #define DGM_NEGATIVE_RES        0x16
 197
 198 int AliasHandleUdpNbt(
 199         struct ip                       *pip,    /* IP packet to examine/patch */
 200         struct alias_link       *link,
 201         struct in_addr          *alias_address,
 202     u_short             alias_port
 203 ) {
 204     struct udphdr *     uh;
 205     NbtDataHeader       *ndh;
 206     u_char              *p = NULL;
 207     char                *pmax;
 208
 209     /* Calculate data length of UDP packet */
 210     uh =  (struct udphdr *) ((char *) pip + (pip->ip_hl << 2));
 211     pmax = (char *)uh + ntohs( uh->uh_ulen );
 212
 213         ndh = (NbtDataHeader *)((char *)uh + (sizeof (struct udphdr)));
 214     if ((char *)(ndh + 1) > pmax)
 215             return(-1);
 216 #ifdef DEBUG
 217         printf("\nType=%02x,", ndh->type );
 218 #endif
 219         switch ( ndh->type ) {
 220                 case DGM_DIRECT_UNIQ:
 221                 case DGM_DIRECT_GROUP:
 222                 case DGM_BROADCAST:
 223                         p = (u_char *)ndh + 14;
 224                     p = AliasHandleName ( p, pmax ); /* Source Name */
 225                     p = AliasHandleName ( p, pmax ); /* Destination Name */
 226                         break;
 227                 case DGM_ERROR:
 228                         p = (u_char *)ndh + 11;
 229                         break;
 230                 case DGM_QUERY:
 231                 case DGM_POSITIVE_RES:
 232                 case DGM_NEGATIVE_RES:
 233                         p = (u_char *)ndh + 10;
 234                     p = AliasHandleName ( p, pmax ); /* Destination Name */
 235                         break;
 236         }
 237     if (p == NULL || (char *)p > pmax)
 238             p = NULL;
 239 #ifdef DEBUG
 240         printf("%s:%d-->", inet_ntoa(ndh->source_ip), ntohs(ndh->source_port) );
 241 #endif
 242         /* Doing a IP address and Port number Translation */
 243         if ( uh->uh_sum != 0 ) {
 244                 int                             acc;
 245                 u_short                 *sptr;
 246                 acc  = ndh->source_port;
 247                 acc -= alias_port;
 248                 sptr = (u_short *) &(ndh->source_ip);
 249                 acc += *sptr++;
 250                 acc += *sptr;
 251                 sptr = (u_short *) alias_address;
 252                 acc -= *sptr++;
 253                 acc -= *sptr;
 254                 ADJUST_CHECKSUM(acc, uh->uh_sum);
 255         }
 256     ndh->source_ip = *alias_address;
 257     ndh->source_port = alias_port;
 258 #ifdef DEBUG
 259         printf("%s:%d\n", inet_ntoa(ndh->source_ip), ntohs(ndh->source_port) );
 260         fflush(stdout);
 261 #endif
 262     return((p == NULL) ? -1 : 0);
 263 }
 264 /* Question Section */
 265 #define QS_TYPE_NB              0x0020
 266 #define QS_TYPE_NBSTAT  0x0021
 267 #define QS_CLAS_IN              0x0001
 268 typedef struct {
 269         u_short type;   /* The type of Request */
 270         u_short class;  /* The class of Request */
 271 } NBTNsQuestion;
 272
 273 static u_char *
 274 AliasHandleQuestion(
 275     u_short count,
 276                                                         NBTNsQuestion *q,
 277     char *pmax,
 278                                                         NBTArguments  *nbtarg)
 279 {
 280
 281         while ( count != 0 ) {
 282                 /* Name Filed */
 283                 q = (NBTNsQuestion *)AliasHandleName((u_char *)q, pmax);
 284
 285                 if (q == NULL || (char *)(q + 1) > pmax) {
 286                         q = NULL;
 287                         break;
 288                 }
 289
 290                 /* Type and Class filed */
 291                 switch ( ntohs(q->type) ) {
 292                         case QS_TYPE_NB:
 293                         case QS_TYPE_NBSTAT:
 294                                 q= q+1;
 295                         break;
 296                         default:
 297 #ifdef DEBUG
 298                                 printf("\nUnknown Type on Question %0x\n", ntohs(q->type) );
 299 #endif
 300                         break;
 301                 }
 302                 count--;
 303         }
 304
 305         /* Set up to out of Question Section */
 306         return ((u_char *)q);
 307 }
 308
 309 /* Resource Record */
 310 #define RR_TYPE_A               0x0001
 311 #define RR_TYPE_NS              0x0002
 312 #define RR_TYPE_NULL    0x000a
 313 #define RR_TYPE_NB              0x0020
 314 #define RR_TYPE_NBSTAT  0x0021
 315 #define RR_CLAS_IN              0x0001
 316 #define SizeOfNsResource        8
 317 typedef struct {
 318         u_short type;
 319         u_short class;
 320         unsigned int ttl;
 321         u_short rdlen;
 322 } NBTNsResource;
 323
 324 #define SizeOfNsRNB                     6
 325 typedef struct {
 326         u_short g:1, ont:2, resv:13;
 327         struct  in_addr addr;
 328 } NBTNsRNB;
 329
 330 static u_char *
 331 AliasHandleResourceNB(
 332     NBTNsResource *q,
 333     char *pmax,
 334                                                            NBTArguments  *nbtarg)
 335 {
 336         NBTNsRNB        *nb;
 337         u_short bcount;
 338
 339         if (q == NULL || (char *)(q + 1) > pmax)
 340                 return(NULL);
 341         /* Check out a length */
 342         bcount = ntohs(q->rdlen);
 343
 344         /* Forward to Resource NB position */
 345         nb = (NBTNsRNB *)((u_char *)q + SizeOfNsResource);
 346
 347         /* Processing all in_addr array */
 348 #ifdef DEBUG
 349         printf("NB rec[%s", inet_ntoa(nbtarg->oldaddr));
 350             printf("->%s, %dbytes] ",inet_ntoa(nbtarg->newaddr ), bcount);
 351 #endif
 352         while ( nb != NULL && bcount != 0 )  {
 353                 if ((char *)(nb + 1) > pmax) {
 354                         nb = NULL;
 355                         break;
 356                 }
 357 #ifdef DEBUG
 358                 printf("<%s>", inet_ntoa(nb->addr) );
 359 #endif
 360                 if (!bcmp(&nbtarg->oldaddr,&nb->addr, sizeof(struct in_addr) ) ) {
 361                         if ( *nbtarg->uh_sum != 0 ) {
 362                 int acc;
 363                 u_short *sptr;
 364
 365                 sptr = (u_short *) &(nb->addr);
 366                 acc = *sptr++;
 367                 acc += *sptr;
 368                 sptr = (u_short *) &(nbtarg->newaddr);
 369                 acc -= *sptr++;
 370                 acc -= *sptr;
 371                 ADJUST_CHECKSUM(acc, *nbtarg->uh_sum);
 372                         }
 373
 374                         nb->addr = nbtarg->newaddr;
 375 #ifdef DEBUG
 376                         printf("O");
 377 #endif
 378                 }
 379 #ifdef DEBUG
 380                  else {
 381                         printf(".");
 382                 }
 383 #endif
 384                 nb=(NBTNsRNB *)((u_char *)nb + SizeOfNsRNB);
 385                 bcount -= SizeOfNsRNB;
 386         }
 387         if (nb == NULL || (char *)(nb + 1) > pmax) {
 388                 nb = NULL;
 389         }
 390
 391         return ((u_char *)nb);
 392 }
 393
 394 #define SizeOfResourceA         6
 395 typedef struct {
 396         struct  in_addr addr;
 397 } NBTNsResourceA;
 398
 399 static u_char *
 400 AliasHandleResourceA(
 401     NBTNsResource *q,
 402     char *pmax,
 403                                                           NBTArguments  *nbtarg)
 404 {
 405         NBTNsResourceA  *a;
 406         u_short bcount;
 407
 408         if (q == NULL || (char *)(q + 1) > pmax)
 409                 return(NULL);
 410
 411         /* Forward to Resource A position */
 412         a = (NBTNsResourceA *)( (u_char *)q + sizeof(NBTNsResource) );
 413
 414         /* Check out of length */
 415         bcount = ntohs(q->rdlen);
 416
 417         /* Processing all in_addr array */
 418 #ifdef DEBUG
 419         printf("Arec [%s", inet_ntoa(nbtarg->oldaddr));
 420         printf("->%s]",inet_ntoa(nbtarg->newaddr ));
 421 #endif
 422         while ( bcount != 0 )  {
 423                 if (a == NULL || (char *)(a + 1) > pmax)
 424                         return(NULL);
 425 #ifdef DEBUG
 426                 printf("..%s", inet_ntoa(a->addr) );
 427 #endif
 428                 if ( !bcmp(&nbtarg->oldaddr, &a->addr, sizeof(struct in_addr) ) ) {
 429                         if ( *nbtarg->uh_sum != 0 ) {
 430                 int acc;
 431                 u_short *sptr;
 432
 433                 sptr = (u_short *) &(a->addr);           /* Old */
 434                 acc = *sptr++;
 435                 acc += *sptr;
 436                 sptr = (u_short *) &nbtarg->newaddr; /* New */
 437                 acc -= *sptr++;
 438                 acc -= *sptr;
 439                 ADJUST_CHECKSUM(acc, *nbtarg->uh_sum);
 440                         }
 441
 442                         a->addr = nbtarg->newaddr;
 443                 }
 444                 a++;    /*XXXX*/
 445                 bcount -= SizeOfResourceA;
 446         }
 447         if (a == NULL || (char *)(a + 1) > pmax)
 448                 a =  NULL;
 449         return ((u_char *)a);
 450 }
 451
 452 typedef struct {
 453         u_short opcode:4, flags:8, resv:4;
 454 } NBTNsResourceNULL;
 455
 456 static u_char *
 457 AliasHandleResourceNULL(
 458     NBTNsResource *q,
 459     char *pmax,
 460                                                              NBTArguments  *nbtarg)
 461 {
 462         NBTNsResourceNULL       *n;
 463         u_short bcount;
 464
 465         if (q == NULL || (char *)(q + 1) > pmax)
 466                 return(NULL);
 467
 468         /* Forward to Resource NULL position */
 469         n = (NBTNsResourceNULL *)( (u_char *)q + sizeof(NBTNsResource) );
 470
 471         /* Check out of length */
 472         bcount = ntohs(q->rdlen);
 473
 474         /* Processing all in_addr array */
 475         while ( bcount != 0 )  {
 476                 if ((char *)(n + 1) > pmax) {
 477                         n = NULL;
 478                         break;
 479                 }
 480                 n++;
 481                 bcount -= sizeof(NBTNsResourceNULL);
 482         }
 483         if ((char *)(n + 1) > pmax)
 484                 n = NULL;
 485
 486         return ((u_char *)n);
 487 }
 488
 489 static u_char *
 490 AliasHandleResourceNS(
 491     NBTNsResource *q,
 492     char *pmax,
 493                                                              NBTArguments  *nbtarg)
 494 {
 495         NBTNsResourceNULL       *n;
 496         u_short bcount;
 497
 498         if (q == NULL || (char *)(q + 1) > pmax)
 499                 return(NULL);
 500
 501         /* Forward to Resource NULL position */
 502         n = (NBTNsResourceNULL *)( (u_char *)q + sizeof(NBTNsResource) );
 503
 504         /* Check out of length */
 505         bcount = ntohs(q->rdlen);
 506
 507         /* Resource Record Name Filed */
 508         q = (NBTNsResource *)AliasHandleName( (u_char *)n, pmax ); /* XXX */
 509
 510         if (q == NULL || (char *)((u_char *)n + bcount) > pmax)
 511                 return(NULL);
 512         else
 513         return ((u_char *)n + bcount);
 514 }
 515
 516 typedef struct {
 517         u_short numnames;
 518 } NBTNsResourceNBSTAT;
 519
 520 static u_char *
 521 AliasHandleResourceNBSTAT(
 522     NBTNsResource *q,
 523     char *pmax,
 524                                                                NBTArguments  *nbtarg)
 525 {
 526         NBTNsResourceNBSTAT     *n;
 527         u_short bcount;
 528
 529         if (q == NULL || (char *)(q + 1) > pmax)
 530                 return(NULL);
 531
 532         /* Forward to Resource NBSTAT position */
 533         n = (NBTNsResourceNBSTAT *)( (u_char *)q + sizeof(NBTNsResource) );
 534
 535         /* Check out of length */
 536         bcount = ntohs(q->rdlen);
 537
 538         if (q == NULL || (char *)((u_char *)n + bcount) > pmax)
 539                 return(NULL);
 540         else
 541         return ((u_char *)n + bcount);
 542 }
 543
 544 static u_char *
 545 AliasHandleResource(
 546     u_short count,
 547                                                         NBTNsResource *q,
 548     char *pmax,
 549     NBTArguments
 550     *nbtarg)
 551 {
 552         while ( count != 0 ) {
 553                 /* Resource Record Name Filed */
 554                 q = (NBTNsResource *)AliasHandleName( (u_char *)q, pmax );
 555
 556                 if (q == NULL || (char *)(q + 1) > pmax)
 557                         break;
 558 #ifdef DEBUG
 559                 printf("type=%02x, count=%d\n", ntohs(q->type), count );
 560 #endif
 561
 562                 /* Type and Class filed */
 563                 switch ( ntohs(q->type) ) {
 564                         case RR_TYPE_NB:
 565                                 q = (NBTNsResource *)AliasHandleResourceNB(
 566                                     q,
 567                                     pmax,
 568                                     nbtarg
 569                                 );
 570                                 break;
 571                         case RR_TYPE_A:
 572                                 q = (NBTNsResource *)AliasHandleResourceA(
 573                                     q,
 574                                     pmax,
 575                                     nbtarg
 576                                 );
 577                                 break;
 578                         case RR_TYPE_NS:
 579                                 q = (NBTNsResource *)AliasHandleResourceNS(
 580                                     q,
 581                                     pmax,
 582                                     nbtarg
 583                                 );
 584                                 break;
 585                         case RR_TYPE_NULL:
 586                                 q = (NBTNsResource *)AliasHandleResourceNULL(
 587                                     q,
 588                                     pmax,
 589                                     nbtarg
 590                                 );
 591                                 break;
 592                         case RR_TYPE_NBSTAT:
 593                                 q = (NBTNsResource *)AliasHandleResourceNBSTAT(
 594                                     q,
 595                                     pmax,
 596                                     nbtarg
 597                                 );
 598                                 break;
 599                         default:
 600 #ifdef DEBUG
 601                                 printf(
 602                                     "\nUnknown Type of Resource %0x\n",
 603                                     ntohs(q->type)
 604                                 );
 605 #endif
 606                                 break;
 607                 }
 608                 count--;
 609         }
 610         fflush(stdout);
 611         return ((u_char *)q);
 612 }
 613
 614 int AliasHandleUdpNbtNS(
 615         struct ip                       *pip,    /* IP packet to examine/patch */
 616         struct alias_link       *link,
 617         struct in_addr          *alias_address,
 618         u_short                         *alias_port,
 619         struct in_addr          *original_address,
 620         u_short                         *original_port )
 621 {
 622     struct udphdr *     uh;
 623         NbtNSHeader       * nsh;
 624         u_char            * p;
 625         char            *pmax;
 626         NBTArguments    nbtarg;
 627
 628         /* Set up Common Parameter */
 629         nbtarg.oldaddr  =       *alias_address;
 630         nbtarg.oldport  =       *alias_port;
 631         nbtarg.newaddr  =       *original_address;
 632         nbtarg.newport  =       *original_port;
 633
 634     /* Calculate data length of UDP packet */
 635     uh =  (struct udphdr *) ((char *) pip + (pip->ip_hl << 2));
 636         nbtarg.uh_sum   =       &(uh->uh_sum);
 637         nsh = (NbtNSHeader *)((char *)uh + (sizeof(struct udphdr)));
 638         p = (u_char *)(nsh + 1);
 639     pmax = (char *)uh + ntohs( uh->uh_ulen );
 640
 641     if ((char *)(nsh + 1) > pmax)
 642         return(-1);
 643
 644 #ifdef DEBUG
 645     printf(" [%s] ID=%02x, op=%01x, flag=%02x, rcode=%01x, qd=%04x"
 646            ", an=%04x, ns=%04x, ar=%04x, [%d]-->",
 647                 nsh->dir ? "Response": "Request",
 648                 nsh->nametrid,
 649                 nsh->opcode,
 650                 nsh->nmflags,
 651                 nsh->rcode,
 652                 ntohs(nsh->qdcount),
 653                 ntohs(nsh->ancount),
 654                 ntohs(nsh->nscount),
 655                 ntohs(nsh->arcount),
 656         (u_char *)p -(u_char *)nsh
 657     );
 658 #endif
 659
 660         /* Question Entries */
 661         if (ntohs(nsh->qdcount) !=0 ) {
 662         p = AliasHandleQuestion(
 663             ntohs(nsh->qdcount),
 664             (NBTNsQuestion *)p,
 665             pmax,
 666             &nbtarg
 667         );
 668         }
 669
 670         /* Answer Resource Records */
 671         if (ntohs(nsh->ancount) !=0 ) {
 672         p = AliasHandleResource(
 673             ntohs(nsh->ancount),
 674             (NBTNsResource *)p,
 675             pmax,
 676             &nbtarg
 677         );
 678         }
 679
 680         /* Authority Resource Recodrs */
 681         if (ntohs(nsh->nscount) !=0 ) {
 682         p = AliasHandleResource(
 683             ntohs(nsh->nscount),
 684             (NBTNsResource *)p,
 685             pmax,
 686             &nbtarg
 687         );
 688         }
 689
 690         /* Additional Resource Recodrs */
 691         if (ntohs(nsh->arcount) !=0 ) {
 692         p = AliasHandleResource(
 693             ntohs(nsh->arcount),
 694             (NBTNsResource *)p,
 695             pmax,
 696             &nbtarg
 697         );
 698         }
 699
 700 #ifdef DEBUG
 701                 PrintRcode(nsh->rcode);
 702 #endif
 703     return ((p == NULL) ? -1 : 0);
 704 }