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[/] [openrisc/] [trunk/] [gnu-stable/] [newlib-1.18.0/] [newlib/] [libc/] [sys/] [linux/] [net/] [ns_name.c] - Blame information for rev 859

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Line No. Rev Author Line
1 207 jeremybenn
/*
2
 * Copyright (c) 1996,1999 by Internet Software Consortium.
3
 *
4
 * Permission to use, copy, modify, and distribute this software for any
5
 * purpose with or without fee is hereby granted, provided that the above
6
 * copyright notice and this permission notice appear in all copies.
7
 *
8
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
9
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
10
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
11
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
12
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
13
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
14
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
15
 * SOFTWARE.
16
 */
17
 
18
#if !defined(_LIBC) && !defined(lint)
19
static const char rcsid[] = "$BINDId: ns_name.c,v 8.15 2000/03/30 22:53:46 vixie Exp $";
20
#endif
21
 
22
#include <sys/types.h>
23
 
24
#include <netinet/in.h>
25
#include <arpa/nameser.h>
26
 
27
#include <ctype.h>
28
#include <errno.h>
29
#include <resolv.h>
30
#include <string.h>
31
#include <ctype.h>
32
#include "libc-symbols.h"
33
 
34
/* Data. */
35
 
36
static const char       digits[] = "0123456789";
37
 
38
/* Forward. */
39
 
40
static int              special(int);
41
static int              printable(int);
42
static int              dn_find(const u_char *, const u_char *,
43
                                const u_char * const *,
44
                                const u_char * const *);
45
 
46
/* Public. */
47
 
48
/*
49
 * ns_name_ntop(src, dst, dstsiz)
50
 *      Convert an encoded domain name to printable ascii as per RFC1035.
51
 * return:
52
 *      Number of bytes written to buffer, or -1 (with errno set)
53
 * notes:
54
 *      The root is returned as "."
55
 *      All other domains are returned in non absolute form
56
 */
57
int
58
ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) {
59
        const u_char *cp;
60
        char *dn, *eom;
61
        u_char c;
62
        u_int n;
63
 
64
        cp = src;
65
        dn = dst;
66
        eom = dst + dstsiz;
67
 
68
        while ((n = *cp++) != 0) {
69
                if ((n & NS_CMPRSFLGS) != 0 && n != 0x41) {
70
                        /* Some kind of compression pointer. */
71
                        __set_errno (EMSGSIZE);
72
                        return (-1);
73
                }
74
                if (dn != dst) {
75
                        if (dn >= eom) {
76
                                __set_errno (EMSGSIZE);
77
                                return (-1);
78
                        }
79
                        *dn++ = '.';
80
                }
81
 
82
                if (n == 0x41) {
83
                        n = *cp++ / 8;
84
                        if (dn + n * 2 + 4 >= eom) {
85
                                __set_errno (EMSGSIZE);
86
                                return (-1);
87
                        }
88
                        *dn++ = '\\';
89
                        *dn++ = '[';
90
                        *dn++ = 'x';
91
 
92
                        while (n-- > 0) {
93
                                c = *cp++;
94
                                unsigned u = c >> 4;
95
                                *dn++ = u > 9 ? 'a' + u - 10 : '0' + u;
96
                                u = c & 0xf;
97
                                *dn++ = u > 9 ? 'a' + u - 10 : '0' + u;
98
                        }
99
 
100
                        *dn++ = ']';
101
                        continue;
102
                }
103
 
104
                if (dn + n >= eom) {
105
                        __set_errno (EMSGSIZE);
106
                        return (-1);
107
                }
108
                for ((void)NULL; n > 0; n--) {
109
                        c = *cp++;
110
                        if (special(c)) {
111
                                if (dn + 1 >= eom) {
112
                                        __set_errno (EMSGSIZE);
113
                                        return (-1);
114
                                }
115
                                *dn++ = '\\';
116
                                *dn++ = (char)c;
117
                        } else if (!printable(c)) {
118
                                if (dn + 3 >= eom) {
119
                                        __set_errno (EMSGSIZE);
120
                                        return (-1);
121
                                }
122
                                *dn++ = '\\';
123
                                *dn++ = digits[c / 100];
124
                                *dn++ = digits[(c % 100) / 10];
125
                                *dn++ = digits[c % 10];
126
                        } else {
127
                                if (dn >= eom) {
128
                                        __set_errno (EMSGSIZE);
129
                                        return (-1);
130
                                }
131
                                *dn++ = (char)c;
132
                        }
133
                }
134
        }
135
        if (dn == dst) {
136
                if (dn >= eom) {
137
                        __set_errno (EMSGSIZE);
138
                        return (-1);
139
                }
140
                *dn++ = '.';
141
        }
142
        if (dn >= eom) {
143
                __set_errno (EMSGSIZE);
144
                return (-1);
145
        }
146
        *dn++ = '\0';
147
        return (dn - dst);
148
}
149
libresolv_hidden_def (ns_name_ntop)
150
 
151
/*
152
 * ns_name_pton(src, dst, dstsiz)
153
 *      Convert a ascii string into an encoded domain name as per RFC1035.
154
 * return:
155
 *      -1 if it fails
156
 *      1 if string was fully qualified
157
 *      0 is string was not fully qualified
158
 * notes:
159
 *      Enforces label and domain length limits.
160
 */
161
 
162
int
163
ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
164
        u_char *label, *bp, *eom;
165
        int c, n, escaped;
166
        char *cp;
167
 
168
        escaped = 0;
169
        bp = dst;
170
        eom = dst + dstsiz;
171
        label = bp++;
172
 
173
        while ((c = *src++) != 0) {
174
                if (escaped) {
175
                        if ((cp = strchr(digits, c)) != NULL) {
176
                                n = (cp - digits) * 100;
177
                                if ((c = *src++) == 0 ||
178
                                    (cp = strchr(digits, c)) == NULL) {
179
                                        __set_errno (EMSGSIZE);
180
                                        return (-1);
181
                                }
182
                                n += (cp - digits) * 10;
183
                                if ((c = *src++) == 0 ||
184
                                    (cp = strchr(digits, c)) == NULL) {
185
                                        __set_errno (EMSGSIZE);
186
                                        return (-1);
187
                                }
188
                                n += (cp - digits);
189
                                if (n > 255) {
190
                                        __set_errno (EMSGSIZE);
191
                                        return (-1);
192
                                }
193
                                c = n;
194
                        } else if (c == '[' && label == bp - 1 && *src == 'x') {
195
                                /* Theoretically we would have to handle \[o
196
                                   as well but we do not since we do not need
197
                                   it internally.  */
198
                                *label = 0x41;
199
                                label = bp++;
200
                                ++src;
201
                                while (isxdigit (*src)) {
202
                                        n = *src > '9' ? *src - 'a' + 10 : *src - '0';
203
                                        ++src;
204
                                        if (! isxdigit(*src)) {
205
                                                __set_errno (EMSGSIZE);
206
                                                return (-1);
207
                                        }
208
                                        n <<= 4;
209
                                        n += *src > '9' ? *src - 'a' + 10 : *src - '0';
210
                                        if (bp + 1 >= eom) {
211
                                                __set_errno (EMSGSIZE);
212
                                                return (-1);
213
                                        }
214
                                        *bp++ = n;
215
                                        ++src;
216
                                }
217
                                *label = (bp - label - 1) * 8;
218
                                if (*src++ != ']' || *src++ != '.') {
219
                                        __set_errno (EMSGSIZE);
220
                                        return (-1);
221
                                }
222
                                escaped = 0;
223
                                label = bp++;
224
                                if (bp >= eom) {
225
                                        __set_errno (EMSGSIZE);
226
                                        return (-1);
227
                                }
228
                                continue;
229
                        }
230
                        escaped = 0;
231
                } else if (c == '\\') {
232
                        escaped = 1;
233
                        continue;
234
                } else if (c == '.') {
235
                        c = (bp - label - 1);
236
                        if ((c & NS_CMPRSFLGS) != 0) {   /* Label too big. */
237
                                __set_errno (EMSGSIZE);
238
                                return (-1);
239
                        }
240
                        if (label >= eom) {
241
                                __set_errno (EMSGSIZE);
242
                                return (-1);
243
                        }
244
                        *label = c;
245
                        /* Fully qualified ? */
246
                        if (*src == '\0') {
247
                                if (c != 0) {
248
                                        if (bp >= eom) {
249
                                                __set_errno (EMSGSIZE);
250
                                                return (-1);
251
                                        }
252
                                        *bp++ = '\0';
253
                                }
254
                                if ((bp - dst) > MAXCDNAME) {
255
                                        __set_errno (EMSGSIZE);
256
                                        return (-1);
257
                                }
258
                                return (1);
259
                        }
260
                        if (c == 0 || *src == '.') {
261
                                __set_errno (EMSGSIZE);
262
                                return (-1);
263
                        }
264
                        label = bp++;
265
                        continue;
266
                }
267
                if (bp >= eom) {
268
                        __set_errno (EMSGSIZE);
269
                        return (-1);
270
                }
271
                *bp++ = (u_char)c;
272
        }
273
        c = (bp - label - 1);
274
        if ((c & NS_CMPRSFLGS) != 0) {           /* Label too big. */
275
                __set_errno (EMSGSIZE);
276
                return (-1);
277
        }
278
        if (label >= eom) {
279
                __set_errno (EMSGSIZE);
280
                return (-1);
281
        }
282
        *label = c;
283
        if (c != 0) {
284
                if (bp >= eom) {
285
                        __set_errno (EMSGSIZE);
286
                        return (-1);
287
                }
288
                *bp++ = 0;
289
        }
290
        if ((bp - dst) > MAXCDNAME) {   /* src too big */
291
                __set_errno (EMSGSIZE);
292
                return (-1);
293
        }
294
        return (0);
295
}
296
 
297
/*
298
 * ns_name_ntol(src, dst, dstsiz)
299
 *      Convert a network strings labels into all lowercase.
300
 * return:
301
 *      Number of bytes written to buffer, or -1 (with errno set)
302
 * notes:
303
 *      Enforces label and domain length limits.
304
 */
305
 
306
int
307
ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz) {
308
        const u_char *cp;
309
        u_char *dn, *eom;
310
        u_char c;
311
        u_int n;
312
 
313
        cp = src;
314
        dn = dst;
315
        eom = dst + dstsiz;
316
 
317
        while ((n = *cp++) != 0) {
318
                if ((n & NS_CMPRSFLGS) != 0) {
319
                        /* Some kind of compression pointer. */
320
                        __set_errno (EMSGSIZE);
321
                        return (-1);
322
                }
323
                *dn++ = n;
324
                if (dn + n >= eom) {
325
                        __set_errno (EMSGSIZE);
326
                        return (-1);
327
                }
328
                for ((void)NULL; n > 0; n--) {
329
                        c = *cp++;
330
                        if (isupper(c))
331
                                *dn++ = tolower(c);
332
                        else
333
                                *dn++ = c;
334
                }
335
        }
336
        *dn++ = '\0';
337
        return (dn - dst);
338
}
339
 
340
/*
341
 * ns_name_unpack(msg, eom, src, dst, dstsiz)
342
 *      Unpack a domain name from a message, source may be compressed.
343
 * return:
344
 *      -1 if it fails, or consumed octets if it succeeds.
345
 */
346
int
347
ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
348
               u_char *dst, size_t dstsiz)
349
{
350
        const u_char *srcp, *dstlim;
351
        u_char *dstp;
352
        int n, len, checked;
353
 
354
        len = -1;
355
        checked = 0;
356
        dstp = dst;
357
        srcp = src;
358
        dstlim = dst + dstsiz;
359
        if (srcp < msg || srcp >= eom) {
360
                __set_errno (EMSGSIZE);
361
                return (-1);
362
        }
363
        /* Fetch next label in domain name. */
364
        while ((n = *srcp++) != 0) {
365
                /* Check for indirection. */
366
                switch (n & NS_CMPRSFLGS) {
367
                case 0x40:
368
                        if (n == 0x41) {
369
                                if (dstp + 1 >= dstlim) {
370
                                        __set_errno (EMSGSIZE);
371
                                        return (-1);
372
                                }
373
                                *dstp++ = 0x41;
374
                                n = *srcp++ / 8;
375
                                ++checked;
376
                        } else {
377
                                __set_errno (EMSGSIZE);
378
                                return (-1);            /* flag error */
379
                        }
380
                        /* FALLTHROUGH */
381
                case 0:
382
                        /* Limit checks. */
383
                        if (dstp + n + 1 >= dstlim || srcp + n >= eom) {
384
                                __set_errno (EMSGSIZE);
385
                                return (-1);
386
                        }
387
                        checked += n + 1;
388
                        dstp = mempcpy(dstp, srcp - 1, n + 1);
389
                        srcp += n;
390
                        break;
391
 
392
                case NS_CMPRSFLGS:
393
                        if (srcp >= eom) {
394
                                __set_errno (EMSGSIZE);
395
                                return (-1);
396
                        }
397
                        if (len < 0)
398
                                len = srcp - src + 1;
399
                        srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
400
                        if (srcp < msg || srcp >= eom) {  /* Out of range. */
401
                                __set_errno (EMSGSIZE);
402
                                return (-1);
403
                        }
404
                        checked += 2;
405
                        /*
406
                         * Check for loops in the compressed name;
407
                         * if we've looked at the whole message,
408
                         * there must be a loop.
409
                         */
410
                        if (checked >= eom - msg) {
411
                                __set_errno (EMSGSIZE);
412
                                return (-1);
413
                        }
414
                        break;
415
 
416
                default:
417
                        __set_errno (EMSGSIZE);
418
                        return (-1);                    /* flag error */
419
                }
420
        }
421
        *dstp = '\0';
422
        if (len < 0)
423
                len = srcp - src;
424
        return (len);
425
}
426
libresolv_hidden_def (ns_name_unpack)
427
 
428
/*
429
 * ns_name_pack(src, dst, dstsiz, dnptrs, lastdnptr)
430
 *      Pack domain name 'domain' into 'comp_dn'.
431
 * return:
432
 *      Size of the compressed name, or -1.
433
 * notes:
434
 *      'dnptrs' is an array of pointers to previous compressed names.
435
 *      dnptrs[0] is a pointer to the beginning of the message. The array
436
 *      ends with NULL.
437
 *      'lastdnptr' is a pointer to the end of the array pointed to
438
 *      by 'dnptrs'.
439
 * Side effects:
440
 *      The list of pointers in dnptrs is updated for labels inserted into
441
 *      the message as we compress the name.  If 'dnptr' is NULL, we don't
442
 *      try to compress names. If 'lastdnptr' is NULL, we don't update the
443
 *      list.
444
 */
445
int
446
ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
447
             const u_char **dnptrs, const u_char **lastdnptr)
448
{
449
        u_char *dstp;
450
        const u_char **cpp, **lpp, *eob, *msg;
451
        const u_char *srcp;
452
        int n, l, first = 1;
453
 
454
        srcp = src;
455
        dstp = dst;
456
        eob = dstp + dstsiz;
457
        lpp = cpp = NULL;
458
        if (dnptrs != NULL) {
459
                if ((msg = *dnptrs++) != NULL) {
460
                        for (cpp = dnptrs; *cpp != NULL; cpp++)
461
                                (void)NULL;
462
                        lpp = cpp;      /* end of list to search */
463
                }
464
        } else
465
                msg = NULL;
466
 
467
        /* make sure the domain we are about to add is legal */
468
        l = 0;
469
        do {
470
                n = *srcp;
471
                if ((n & NS_CMPRSFLGS) != 0 && n != 0x41) {
472
                        __set_errno (EMSGSIZE);
473
                        return (-1);
474
                }
475
                if (n == 0x41)
476
                        n = *++srcp / 8;
477
                l += n + 1;
478
                if (l > MAXCDNAME) {
479
                        __set_errno (EMSGSIZE);
480
                        return (-1);
481
                }
482
                srcp += n + 1;
483
        } while (n != 0);
484
 
485
        /* from here on we need to reset compression pointer array on error */
486
        srcp = src;
487
        do {
488
                /* Look to see if we can use pointers. */
489
                n = *srcp;
490
                if (n != 0 && n != 0x41 && msg != NULL) {
491
                        l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
492
                                    (const u_char * const *)lpp);
493
                        if (l >= 0) {
494
                                if (dstp + 1 >= eob) {
495
                                        goto cleanup;
496
                                }
497
                                *dstp++ = (l >> 8) | NS_CMPRSFLGS;
498
                                *dstp++ = l % 256;
499
                                return (dstp - dst);
500
                        }
501
                        /* Not found, save it. */
502
                        if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
503
                            (dstp - msg) < 0x4000 && first) {
504
                                *cpp++ = dstp;
505
                                *cpp = NULL;
506
                                first = 0;
507
                        }
508
                }
509
                /* copy label to buffer */
510
                if ((n & NS_CMPRSFLGS) != 0 && n != 0x41) {              /* Should not happen. */
511
                        goto cleanup;
512
                }
513
                if (n == 0x41) {
514
                        n = *++srcp / 8;
515
                        if (dstp + 1 >= eob)
516
                                goto cleanup;
517
                        *dstp++ = 0x41;
518
                }
519
                if (dstp + 1 + n >= eob) {
520
                        goto cleanup;
521
                }
522
                memcpy(dstp, srcp, n + 1);
523
                srcp += n + 1;
524
                dstp += n + 1;
525
        } while (n != 0);
526
 
527
        if (dstp > eob) {
528
cleanup:
529
                if (msg != NULL)
530
                        *lpp = NULL;
531
                __set_errno (EMSGSIZE);
532
                return (-1);
533
        }
534
        return (dstp - dst);
535
}
536
 
537
/*
538
 * ns_name_uncompress(msg, eom, src, dst, dstsiz)
539
 *      Expand compressed domain name to presentation format.
540
 * return:
541
 *      Number of bytes read out of `src', or -1 (with errno set).
542
 * note:
543
 *      Root domain returns as "." not "".
544
 */
545
int
546
ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
547
                   char *dst, size_t dstsiz)
548
{
549
        u_char tmp[NS_MAXCDNAME];
550
        int n;
551
 
552
        if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
553
                return (-1);
554
        if (ns_name_ntop(tmp, dst, dstsiz) == -1)
555
                return (-1);
556
        return (n);
557
}
558
 
559
/*
560
 * ns_name_compress(src, dst, dstsiz, dnptrs, lastdnptr)
561
 *      Compress a domain name into wire format, using compression pointers.
562
 * return:
563
 *      Number of bytes consumed in `dst' or -1 (with errno set).
564
 * notes:
565
 *      'dnptrs' is an array of pointers to previous compressed names.
566
 *      dnptrs[0] is a pointer to the beginning of the message.
567
 *      The list ends with NULL.  'lastdnptr' is a pointer to the end of the
568
 *      array pointed to by 'dnptrs'. Side effect is to update the list of
569
 *      pointers for labels inserted into the message as we compress the name.
570
 *      If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
571
 *      is NULL, we don't update the list.
572
 */
573
int
574
ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
575
                 const u_char **dnptrs, const u_char **lastdnptr)
576
{
577
        u_char tmp[NS_MAXCDNAME];
578
 
579
        if (ns_name_pton(src, tmp, sizeof tmp) == -1)
580
                return (-1);
581
        return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
582
}
583
 
584
/*
585
 * Reset dnptrs so that there are no active references to pointers at or
586
 * after src.
587
 */
588
void
589
ns_name_rollback(const u_char *src, const u_char **dnptrs,
590
                 const u_char **lastdnptr)
591
{
592
        while (dnptrs < lastdnptr && *dnptrs != NULL) {
593
                if (*dnptrs >= src) {
594
                        *dnptrs = NULL;
595
                        break;
596
                }
597
                dnptrs++;
598
        }
599
}
600
 
601
/*
602
 * ns_name_skip(ptrptr, eom)
603
 *      Advance *ptrptr to skip over the compressed name it points at.
604
 * return:
605
 *      0 on success, -1 (with errno set) on failure.
606
 */
607
int
608
ns_name_skip(const u_char **ptrptr, const u_char *eom) {
609
        const u_char *cp;
610
        u_int n;
611
 
612
        cp = *ptrptr;
613
        while (cp < eom && (n = *cp++) != 0) {
614
                /* Check for indirection. */
615
                switch (n & NS_CMPRSFLGS) {
616
                case 0:                  /* normal case, n == len */
617
                        cp += n;
618
                        continue;
619
                case NS_CMPRSFLGS:      /* indirection */
620
                        cp++;
621
                        break;
622
                default:                /* illegal type */
623
                        __set_errno (EMSGSIZE);
624
                        return (-1);
625
                }
626
                break;
627
        }
628
        if (cp > eom) {
629
                __set_errno (EMSGSIZE);
630
                return (-1);
631
        }
632
        *ptrptr = cp;
633
        return (0);
634
}
635
 
636
/* Private. */
637
 
638
/*
639
 * special(ch)
640
 *      Thinking in noninternationalized USASCII (per the DNS spec),
641
 *      is this characted special ("in need of quoting") ?
642
 * return:
643
 *      boolean.
644
 */
645
static int
646
special(int ch) {
647
        switch (ch) {
648
        case 0x22: /* '"' */
649
        case 0x2E: /* '.' */
650
        case 0x3B: /* ';' */
651
        case 0x5C: /* '\\' */
652
        /* Special modifiers in zone files. */
653
        case 0x40: /* '@' */
654
        case 0x24: /* '$' */
655
                return (1);
656
        default:
657
                return (0);
658
        }
659
}
660
 
661
/*
662
 * printable(ch)
663
 *      Thinking in noninternationalized USASCII (per the DNS spec),
664
 *      is this character visible and not a space when printed ?
665
 * return:
666
 *      boolean.
667
 */
668
static int
669
printable(int ch) {
670
        return (ch > 0x20 && ch < 0x7f);
671
}
672
 
673
/*
674
 *      Thinking in noninternationalized USASCII (per the DNS spec),
675
 *      convert this character to lower case if it's upper case.
676
 */
677
static int
678
mklower(int ch) {
679
        if (ch >= 0x41 && ch <= 0x5A)
680
                return (ch + 0x20);
681
        return (ch);
682
}
683
 
684
/*
685
 * dn_find(domain, msg, dnptrs, lastdnptr)
686
 *      Search for the counted-label name in an array of compressed names.
687
 * return:
688
 *      offset from msg if found, or -1.
689
 * notes:
690
 *      dnptrs is the pointer to the first name on the list,
691
 *      not the pointer to the start of the message.
692
 */
693
static int
694
dn_find(const u_char *domain, const u_char *msg,
695
        const u_char * const *dnptrs,
696
        const u_char * const *lastdnptr)
697
{
698
        const u_char *dn, *cp, *sp;
699
        const u_char * const *cpp;
700
        u_int n;
701
 
702
        for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
703
                sp = *cpp;
704
                /*
705
                 * terminate search on:
706
                 * root label
707
                 * compression pointer
708
                 * unusable offset
709
                 */
710
                while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
711
                       (sp - msg) < 0x4000) {
712
                        dn = domain;
713
                        cp = sp;
714
                        while ((n = *cp++) != 0) {
715
                                /*
716
                                 * check for indirection
717
                                 */
718
                                switch (n & NS_CMPRSFLGS) {
719
                                case 0:          /* normal case, n == len */
720
                                        if (n != *dn++)
721
                                                goto next;
722
                                        for ((void)NULL; n > 0; n--)
723
                                                if (mklower(*dn++) !=
724
                                                    mklower(*cp++))
725
                                                        goto next;
726
                                        /* Is next root for both ? */
727
                                        if (*dn == '\0' && *cp == '\0')
728
                                                return (sp - msg);
729
                                        if (*dn)
730
                                                continue;
731
                                        goto next;
732
 
733
                                case NS_CMPRSFLGS:      /* indirection */
734
                                        cp = msg + (((n & 0x3f) << 8) | *cp);
735
                                        break;
736
 
737
                                default:        /* illegal type */
738
                                        __set_errno (EMSGSIZE);
739
                                        return (-1);
740
                                }
741
                        }
742
 next:
743
                        sp += *sp + 1;
744
                }
745
        }
746
        __set_errno (ENOENT);
747
        return (-1);
748
}

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