2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996,1999 by Internet Software Consortium.
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19 static const char rcsid[] = "$Id: ns_name.c,v 1.10 2005/04/27 04:56:40 sra Exp $";
22 #include "port_before.h"
24 #include <sys/types.h>
26 #include <netinet/in.h>
27 #include <arpa/nameser.h>
36 #include "port_after.h"
39 # define SPRINTF(x) strlen(sprintf/**/x)
41 # define SPRINTF(x) ((size_t)sprintf x)
44 #define NS_TYPE_ELT 0x40 /*%< EDNS0 extended label type */
45 #define DNS_LABELTYPE_BITSTRING 0x41
49 static const char digits[] = "0123456789";
51 static const char digitvalue[256] = {
52 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*16*/
53 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*32*/
54 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*48*/
55 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, /*64*/
56 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*80*/
57 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*96*/
58 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*112*/
59 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*128*/
60 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
61 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
62 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
63 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
64 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
65 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
66 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
67 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*256*/
72 static int special(int);
73 static int printable(int);
74 static int dn_find(const u_char *, const u_char *,
75 const u_char * const *,
76 const u_char * const *);
77 static int encode_bitsring(const char **, const char *,
78 unsigned char **, unsigned char **,
79 unsigned const char *);
80 static int labellen(const u_char *);
81 static int decode_bitstring(const unsigned char **,
82 char *, const char *);
87 * Convert an encoded domain name to printable ascii as per RFC1035.
90 *\li Number of bytes written to buffer, or -1 (with errno set)
93 *\li The root is returned as "."
94 *\li All other domains are returned in non absolute form
97 ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
109 while ((n = *cp++) != 0) {
110 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
111 /* Some kind of compression pointer. */
122 if ((l = labellen(cp - 1)) < 0) {
123 errno = EMSGSIZE; /*%< XXX */
130 if ((n & NS_CMPRSFLGS) == NS_TYPE_ELT) {
133 if (n != DNS_LABELTYPE_BITSTRING) {
134 /* XXX: labellen should reject this case */
138 if ((m = decode_bitstring(&cp, dn, eom)) < 0)
146 for ((void)NULL; l > 0; l--) {
155 } else if (!printable(c)) {
161 *dn++ = digits[c / 100];
162 *dn++ = digits[(c % 100) / 10];
163 *dn++ = digits[c % 10];
189 * Convert a ascii string into an encoded domain name as per RFC1035.
194 *\li 1 if string was fully qualified
195 *\li 0 is string was not fully qualified
198 *\li Enforces label and domain length limits.
202 ns_name_pton(const char *src, u_char *dst, size_t dstsiz)
204 u_char *label, *bp, *eom;
205 int c, n, escaped, e = 0;
213 while ((c = *src++) != 0) {
215 if (c == '[') { /*%< start a bit string label */
216 if ((cp = strchr(src, ']')) == NULL) {
217 errno = EINVAL; /*%< ??? */
220 if ((e = encode_bitsring(&src, cp + 2,
228 if ((c = *src++) == 0)
236 else if ((cp = strchr(digits, c)) != NULL) {
237 n = (cp - digits) * 100;
238 if ((c = *src++) == 0 ||
239 (cp = strchr(digits, c)) == NULL) {
243 n += (cp - digits) * 10;
244 if ((c = *src++) == 0 ||
245 (cp = strchr(digits, c)) == NULL) {
257 } else if (c == '\\') {
260 } else if (c == '.') {
261 c = (bp - label - 1);
262 if ((c & NS_CMPRSFLGS) != 0) { /*%< Label too big. */
271 /* Fully qualified ? */
280 if ((bp - dst) > MAXCDNAME) {
286 if (c == 0 || *src == '.') {
299 c = (bp - label - 1);
300 if ((c & NS_CMPRSFLGS) != 0) { /*%< Label too big. */
317 if ((bp - dst) > MAXCDNAME) { /*%< src too big */
325 * Convert a network strings labels into all lowercase.
328 *\li Number of bytes written to buffer, or -1 (with errno set)
331 *\li Enforces label and domain length limits.
335 ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
351 while ((n = *cp++) != 0) {
352 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
353 /* Some kind of compression pointer. */
358 if ((l = labellen(cp - 1)) < 0) {
366 for ((void)NULL; l > 0; l--) {
379 * Unpack a domain name from a message, source may be compressed.
382 *\li -1 if it fails, or consumed octets if it succeeds.
385 ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
386 u_char *dst, size_t dstsiz)
388 const u_char *srcp, *dstlim;
390 int n, len, checked, l;
396 dstlim = dst + dstsiz;
397 if (srcp < msg || srcp >= eom) {
401 /* Fetch next label in domain name. */
402 while ((n = *srcp++) != 0) {
403 /* Check for indirection. */
404 switch (n & NS_CMPRSFLGS) {
408 if ((l = labellen(srcp - 1)) < 0) {
412 if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
418 memcpy(dstp, srcp, l);
429 len = srcp - src + 1;
430 srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
431 if (srcp < msg || srcp >= eom) { /*%< Out of range. */
437 * Check for loops in the compressed name;
438 * if we've looked at the whole message,
439 * there must be a loop.
441 if (checked >= eom - msg) {
449 return (-1); /*%< flag error */
459 * Pack domain name 'domain' into 'comp_dn'.
462 *\li Size of the compressed name, or -1.
465 *\li 'dnptrs' is an array of pointers to previous compressed names.
466 *\li dnptrs[0] is a pointer to the beginning of the message. The array
468 *\li 'lastdnptr' is a pointer to the end of the array pointed to
472 *\li The list of pointers in dnptrs is updated for labels inserted into
473 * the message as we compress the name. If 'dnptr' is NULL, we don't
474 * try to compress names. If 'lastdnptr' is NULL, we don't update the
478 ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
479 const u_char **dnptrs, const u_char **lastdnptr)
482 const u_char **cpp, **lpp, *eob, *msg;
490 if (dnptrs != NULL) {
491 if ((msg = *dnptrs++) != NULL) {
492 for (cpp = dnptrs; *cpp != NULL; cpp++)
494 lpp = cpp; /*%< end of list to search */
499 /* make sure the domain we are about to add is legal */
505 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
509 if ((l0 = labellen(srcp)) < 0) {
521 /* from here on we need to reset compression pointer array on error */
524 /* Look to see if we can use pointers. */
526 if (n != 0 && msg != NULL) {
527 l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
528 (const u_char * const *)lpp);
530 if (dstp + 1 >= eob) {
533 *dstp++ = (l >> 8) | NS_CMPRSFLGS;
537 /* Not found, save it. */
538 if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
539 (dstp - msg) < 0x4000 && first) {
545 /* copy label to buffer */
546 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
547 /* Should not happen. */
551 if (dstp + 1 + n >= eob) {
554 memcpy(dstp, srcp, n + 1);
570 * Expand compressed domain name to presentation format.
573 *\li Number of bytes read out of `src', or -1 (with errno set).
576 *\li Root domain returns as "." not "".
579 ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
580 char *dst, size_t dstsiz)
582 u_char tmp[NS_MAXCDNAME];
585 if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
587 if (ns_name_ntop(tmp, dst, dstsiz) == -1)
593 * Compress a domain name into wire format, using compression pointers.
596 *\li Number of bytes consumed in `dst' or -1 (with errno set).
599 *\li 'dnptrs' is an array of pointers to previous compressed names.
600 *\li dnptrs[0] is a pointer to the beginning of the message.
601 *\li The list ends with NULL. 'lastdnptr' is a pointer to the end of the
602 * array pointed to by 'dnptrs'. Side effect is to update the list of
603 * pointers for labels inserted into the message as we compress the name.
604 *\li If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
605 * is NULL, we don't update the list.
608 ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
609 const u_char **dnptrs, const u_char **lastdnptr)
611 u_char tmp[NS_MAXCDNAME];
613 if (ns_name_pton(src, tmp, sizeof tmp) == -1)
615 return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
619 * Reset dnptrs so that there are no active references to pointers at or
623 ns_name_rollback(const u_char *src, const u_char **dnptrs,
624 const u_char **lastdnptr)
626 while (dnptrs < lastdnptr && *dnptrs != NULL) {
627 if (*dnptrs >= src) {
636 * Advance *ptrptr to skip over the compressed name it points at.
639 *\li 0 on success, -1 (with errno set) on failure.
642 ns_name_skip(const u_char **ptrptr, const u_char *eom)
649 while (cp < eom && (n = *cp++) != 0) {
650 /* Check for indirection. */
651 switch (n & NS_CMPRSFLGS) {
652 case 0: /*%< normal case, n == len */
655 case NS_TYPE_ELT: /*%< EDNS0 extended label */
656 if ((l = labellen(cp - 1)) < 0) {
657 errno = EMSGSIZE; /*%< XXX */
662 case NS_CMPRSFLGS: /*%< indirection */
665 default: /*%< illegal type */
682 * Thinking in noninternationalized USASCII (per the DNS spec),
683 * is this characted special ("in need of quoting") ?
691 case 0x22: /*%< '"' */
692 case 0x2E: /*%< '.' */
693 case 0x3B: /*%< ';' */
694 case 0x5C: /*%< '\\' */
695 case 0x28: /*%< '(' */
696 case 0x29: /*%< ')' */
697 /* Special modifiers in zone files. */
698 case 0x40: /*%< '@' */
699 case 0x24: /*%< '$' */
707 * Thinking in noninternationalized USASCII (per the DNS spec),
708 * is this character visible and not a space when printed ?
715 return (ch > 0x20 && ch < 0x7f);
719 * Thinking in noninternationalized USASCII (per the DNS spec),
720 * convert this character to lower case if it's upper case.
724 if (ch >= 0x41 && ch <= 0x5A)
730 * Search for the counted-label name in an array of compressed names.
733 *\li offset from msg if found, or -1.
736 *\li dnptrs is the pointer to the first name on the list,
737 *\li not the pointer to the start of the message.
740 dn_find(const u_char *domain, const u_char *msg,
741 const u_char * const *dnptrs,
742 const u_char * const *lastdnptr)
744 const u_char *dn, *cp, *sp;
745 const u_char * const *cpp;
748 for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
751 * terminate search on:
753 * compression pointer
756 while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
757 (sp - msg) < 0x4000) {
760 while ((n = *cp++) != 0) {
762 * check for indirection
764 switch (n & NS_CMPRSFLGS) {
765 case 0: /*%< normal case, n == len */
766 n = labellen(cp - 1); /*%< XXX */
770 for ((void)NULL; n > 0; n--)
771 if (mklower(*dn++) !=
774 /* Is next root for both ? */
775 if (*dn == '\0' && *cp == '\0')
780 case NS_CMPRSFLGS: /*%< indirection */
781 cp = msg + (((n & 0x3f) << 8) | *cp);
784 default: /*%< illegal type */
798 decode_bitstring(const unsigned char **cpp, char *dn, const char *eom)
800 const unsigned char *cp = *cpp;
802 int b, blen, plen, i;
804 if ((blen = (*cp & 0xff)) == 0)
806 plen = (blen + 3) / 4;
807 plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
808 if (dn + plen >= eom)
812 i = SPRINTF((dn, "\\[x"));
816 for (b = blen; b > 7; b -= 8, cp++) {
817 i = SPRINTF((dn, "%02x", *cp & 0xff));
824 i = SPRINTF((dn, "%02x", tc & (0xff << (8 - b))));
830 i = SPRINTF((dn, "%1x",
831 ((tc >> 4) & 0x0f) & (0x0f << (4 - b))));
836 i = SPRINTF((dn, "/%d]", blen));
846 encode_bitsring(const char **bp, const char *end, unsigned char **labelp,
847 unsigned char ** dst, unsigned const char *eom)
850 const char *cp = *bp;
853 const char *beg_blen;
854 char *end_blen = NULL;
855 int value = 0, count = 0, tbcount = 0, blen = 0;
857 beg_blen = end_blen = NULL;
859 /* a bitstring must contain at least 2 characters */
863 /* XXX: currently, only hex strings are supported */
866 if (!isxdigit((*cp) & 0xff)) /*%< reject '\[x/BLEN]' */
869 for (tp = *dst + 1; cp < end && tp < eom; cp++) {
871 case ']': /*%< end of the bitstring */
873 if (beg_blen == NULL)
875 blen = (int)strtol(beg_blen, &end_blen, 10);
876 if (*end_blen != ']')
880 *tp++ = ((value << 4) & 0xff);
881 cp++; /*%< skip ']' */
888 if (!isdigit(c&0xff))
890 if (beg_blen == NULL) {
893 /* blen never begings with 0 */
899 if (!isxdigit(c&0xff))
902 value += digitvalue[(int)c];
916 if (cp >= end || tp >= eom)
920 * bit length validation:
921 * If a <length> is present, the number of digits in the <bit-data>
922 * MUST be just sufficient to contain the number of bits specified
923 * by the <length>. If there are insignificant bits in a final
924 * hexadecimal or octal digit, they MUST be zero.
925 * RFC2673, Section 3.2.
930 if (((blen + 3) & ~3) != tbcount)
932 traillen = tbcount - blen; /*%< between 0 and 3 */
933 if (((value << (8 - traillen)) & 0xff) != 0)
941 /* encode the type and the significant bit fields */
942 **labelp = DNS_LABELTYPE_BITSTRING;
952 labellen(const u_char *lp)
957 if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
958 /* should be avoided by the caller */
962 if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT) {
963 if (l == DNS_LABELTYPE_BITSTRING) {
964 if ((bitlen = *(lp + 1)) == 0)
966 return((bitlen + 7 ) / 8 + 1);
968 return(-1); /*%< unknwon ELT */