You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
 

379 lines
9.7 KiB

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