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379 lines
9.7 KiB
379 lines
9.7 KiB
/* udns_dn.c
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domain names manipulation routines
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Copyright (C) 2005 Michael Tokarev <mjt@corpit.ru>
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This file is part of UDNS library, an async DNS stub resolver.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library, in file named COPYING.LGPL; if not,
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write to the Free Software Foundation, Inc., 59 Temple Place,
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Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <string.h>
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#include "udns.h"
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unsigned dns_dnlen(dnscc_t *dn) {
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register dnscc_t *d = dn;
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while(*d)
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d += 1 + *d;
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return (unsigned)(d - dn) + 1;
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}
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unsigned dns_dnlabels(register dnscc_t *dn) {
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register unsigned l = 0;
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while(*dn)
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++l, dn += 1 + *dn;
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return l;
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}
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unsigned dns_dnequal(register dnscc_t *dn1, register dnscc_t *dn2) {
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register unsigned c;
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dnscc_t *dn = dn1;
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for(;;) {
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if ((c = *dn1++) != *dn2++)
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return 0;
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if (!c)
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return (unsigned)(dn1 - dn);
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while(c--) {
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if (DNS_DNLC(*dn1) != DNS_DNLC(*dn2))
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return 0;
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++dn1; ++dn2;
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}
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}
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}
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unsigned
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dns_dntodn(dnscc_t *sdn, dnsc_t *ddn, unsigned ddnsiz) {
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unsigned sdnlen = dns_dnlen(sdn);
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if (ddnsiz < sdnlen)
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return 0;
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memcpy(ddn, sdn, sdnlen);
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return sdnlen;
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}
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int
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dns_ptodn(const char *name, unsigned namelen,
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dnsc_t *dn, unsigned dnsiz, int *isabs)
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{
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dnsc_t *dp; /* current position in dn (len byte first) */
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dnsc_t *const de /* end of dn: last byte that can be filled up */
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= dn + (dnsiz >= DNS_MAXDN ? DNS_MAXDN : dnsiz) - 1;
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dnscc_t *np = (dnscc_t *)name;
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dnscc_t *ne = np + (namelen ? namelen : strlen((char*)np));
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dnsc_t *llab; /* start of last label (llab[-1] will be length) */
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unsigned c; /* next input character, or length of last label */
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if (!dnsiz)
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return 0;
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dp = llab = dn + 1;
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while(np < ne) {
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if (*np == '.') { /* label delimiter */
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c = dp - llab; /* length of the label */
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if (!c) { /* empty label */
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if (np == (dnscc_t *)name && np + 1 == ne) {
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/* special case for root dn, aka `.' */
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++np;
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break;
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}
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return -1; /* zero label */
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}
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if (c > DNS_MAXLABEL)
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return -1; /* label too long */
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llab[-1] = (dnsc_t)c; /* update len of last label */
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llab = ++dp; /* start new label, llab[-1] will be len of it */
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++np;
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continue;
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}
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/* check whenever we may put out one more byte */
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if (dp >= de) /* too long? */
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return dnsiz >= DNS_MAXDN ? -1 : 0;
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if (*np != '\\') { /* non-escape, simple case */
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*dp++ = *np++;
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continue;
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}
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/* handle \-style escape */
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/* note that traditionally, domain names (gethostbyname etc)
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* used decimal \dd notation, not octal \ooo (RFC1035), so
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* we're following this tradition here.
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*/
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if (++np == ne)
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return -1; /* bad escape */
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else if (*np >= '0' && *np <= '9') { /* decimal number */
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/* we allow not only exactly 3 digits as per RFC1035,
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* but also 2 or 1, for better usability. */
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c = *np++ - '0';
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if (np < ne && *np >= '0' && *np <= '9') { /* 2digits */
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c = c * 10 + *np++ - '0';
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if (np < ne && *np >= '0' && *np <= '9') {
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c = c * 10 + *np++ - '0';
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if (c > 255)
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return -1; /* bad escape */
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}
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}
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}
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else
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c = *np++;
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*dp++ = (dnsc_t)c; /* place next out byte */
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}
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if ((c = dp - llab) > DNS_MAXLABEL)
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return -1; /* label too long */
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if ((llab[-1] = (dnsc_t)c) != 0) {
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*dp++ = 0;
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if (isabs)
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*isabs = 0;
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}
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else if (isabs)
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*isabs = 1;
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return dp - dn;
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}
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dnscc_t dns_inaddr_arpa_dn[14] = "\07in-addr\04arpa";
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dnsc_t *
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dns_a4todn_(const struct in_addr *addr, dnsc_t *dn, dnsc_t *dne) {
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const unsigned char *s = ((const unsigned char *)addr) + 4;
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while(s > (const unsigned char *)addr) {
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unsigned n = *--s;
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dnsc_t *p = dn + 1;
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if (n > 99) {
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if (p + 2 > dne) return 0;
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*p++ = n / 100 + '0';
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*p++ = (n % 100 / 10) + '0';
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*p = n % 10 + '0';
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}
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else if (n > 9) {
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if (p + 1 > dne) return 0;
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*p++ = n / 10 + '0';
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*p = n % 10 + '0';
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}
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else {
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if (p > dne) return 0;
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*p = n + '0';
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}
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*dn = p - dn;
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dn = p + 1;
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}
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return dn;
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}
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int dns_a4todn(const struct in_addr *addr, dnscc_t *tdn,
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dnsc_t *dn, unsigned dnsiz) {
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dnsc_t *dne = dn + (dnsiz > DNS_MAXDN ? DNS_MAXDN : dnsiz);
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dnsc_t *p;
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unsigned l;
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p = dns_a4todn_(addr, dn, dne);
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if (!p) return 0;
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if (!tdn)
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tdn = dns_inaddr_arpa_dn;
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l = dns_dnlen(tdn);
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if (p + l > dne) return dnsiz >= DNS_MAXDN ? -1 : 0;
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memcpy(p, tdn, l);
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return (p + l) - dn;
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}
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int dns_a4ptodn(const struct in_addr *addr, const char *tname,
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dnsc_t *dn, unsigned dnsiz) {
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dnsc_t *p;
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int r;
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if (!tname)
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return dns_a4todn(addr, NULL, dn, dnsiz);
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p = dns_a4todn_(addr, dn, dn + dnsiz);
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if (!p) return 0;
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r = dns_sptodn(tname, p, dnsiz - (p - dn));
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return r != 0 ? r : dnsiz >= DNS_MAXDN ? -1 : 0;
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}
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dnscc_t dns_ip6_arpa_dn[10] = "\03ip6\04arpa";
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dnsc_t *
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dns_a6todn_(const struct in6_addr *addr, dnsc_t *dn, dnsc_t *dne) {
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const unsigned char *s = ((const unsigned char *)addr) + 16;
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if (dn + 64 > dne) return 0;
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while(s > (const unsigned char *)addr) {
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unsigned n = *--s & 0x0f;
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*dn++ = 1;
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*dn++ = n > 9 ? n + 'a' - 10 : n + '0';
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*dn++ = 1;
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n = *s >> 4;
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*dn++ = n > 9 ? n + 'a' - 10 : n + '0';
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}
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return dn;
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}
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int dns_a6todn(const struct in6_addr *addr, dnscc_t *tdn,
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dnsc_t *dn, unsigned dnsiz) {
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dnsc_t *dne = dn + (dnsiz > DNS_MAXDN ? DNS_MAXDN : dnsiz);
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dnsc_t *p;
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unsigned l;
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p = dns_a6todn_(addr, dn, dne);
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if (!p) return 0;
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if (!tdn)
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tdn = dns_ip6_arpa_dn;
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l = dns_dnlen(tdn);
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if (p + l > dne) return dnsiz >= DNS_MAXDN ? -1 : 0;
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memcpy(p, tdn, l);
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return (p + l) - dn;
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}
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int dns_a6ptodn(const struct in6_addr *addr, const char *tname,
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dnsc_t *dn, unsigned dnsiz) {
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dnsc_t *p;
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int r;
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if (!tname)
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return dns_a6todn(addr, NULL, dn, dnsiz);
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p = dns_a6todn_(addr, dn, dn + dnsiz);
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if (!p) return 0;
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r = dns_sptodn(tname, p, dnsiz - (p - dn));
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return r != 0 ? r : dnsiz >= DNS_MAXDN ? -1 : 0;
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}
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/* return size of buffer required to convert the dn into asciiz string.
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* Keep in sync with dns_dntop() below.
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*/
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unsigned dns_dntop_size(dnscc_t *dn) {
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unsigned size = 0; /* the size reqd */
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dnscc_t *le; /* label end */
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while(*dn) {
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/* *dn is the length of the next label, non-zero */
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if (size)
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++size; /* for the dot */
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le = dn + *dn + 1;
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++dn;
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do {
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switch(*dn) {
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case '.':
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case '\\':
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/* Special modifiers in zone files. */
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case '"':
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case ';':
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case '@':
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case '$':
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size += 2;
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break;
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default:
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if (*dn <= 0x20 || *dn >= 0x7f)
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/* \ddd decimal notation */
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size += 4;
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else
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size += 1;
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}
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} while(++dn < le);
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}
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size += 1; /* zero byte at the end - string terminator */
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return size > DNS_MAXNAME ? 0 : size;
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}
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/* Convert the dn into asciiz string.
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* Keep in sync with dns_dntop_size() above.
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*/
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int dns_dntop(dnscc_t *dn, char *name, unsigned namesiz) {
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char *np = name; /* current name ptr */
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char *const ne = name + namesiz; /* end of name */
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dnscc_t *le; /* label end */
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while(*dn) {
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/* *dn is the length of the next label, non-zero */
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if (np != name) {
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if (np >= ne) goto toolong;
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*np++ = '.';
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}
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le = dn + *dn + 1;
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++dn;
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do {
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switch(*dn) {
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case '.':
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case '\\':
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/* Special modifiers in zone files. */
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case '"':
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case ';':
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case '@':
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case '$':
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if (np + 2 > ne) goto toolong;
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*np++ = '\\';
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*np++ = *dn;
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break;
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default:
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if (*dn <= 0x20 || *dn >= 0x7f) {
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/* \ddd decimal notation */
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if (np + 4 >= ne) goto toolong;
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*np++ = '\\';
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*np++ = '0' + (*dn / 100);
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*np++ = '0' + ((*dn % 100) / 10);
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*np++ = '0' + (*dn % 10);
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}
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else {
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if (np >= ne) goto toolong;
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*np++ = *dn;
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}
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}
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} while(++dn < le);
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}
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if (np >= ne) goto toolong;
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*np++ = '\0';
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return np - name;
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toolong:
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return namesiz >= DNS_MAXNAME ? -1 : 0;
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}
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#if 0
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#include <stdio.h>
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#include <stdlib.h>
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int main(int argc, char **argv) {
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int i;
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int sz;
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dnsc_t dn[DNS_MAXDN+10];
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dnsc_t *dl, *dp;
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int isabs;
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sz = (argc > 1) ? atoi(argv[1]) : 0;
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for(i = 2; i < argc; ++i) {
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int r = dns_ptodn(argv[i], 0, dn, sz, &isabs);
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printf("%s: ", argv[i]);
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if (r < 0) printf("error\n");
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else if (!r) printf("buffer too small\n");
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else {
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printf("len=%d dnlen=%d size=%d name:",
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r, dns_dnlen(dn), dns_dntop_size(dn));
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dl = dn;
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while(*dl) {
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printf(" %d=", *dl);
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dp = dl + 1;
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dl = dp + *dl;
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while(dp < dl) {
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if (*dp <= ' ' || *dp >= 0x7f)
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printf("\\%03d", *dp);
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else if (*dp == '.' || *dp == '\\')
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printf("\\%c", *dp);
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else
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putchar(*dp);
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++dp;
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}
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}
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if (isabs) putchar('.');
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putchar('\n');
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}
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}
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return 0;
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}
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#endif /* TEST */
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