594 lines
13 KiB
C
594 lines
13 KiB
C
/*
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* Copyright (c) 1996 by Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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#ifndef lint
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static char rcsid[] = "$Id: ns_name.c,v 8.3 1997/04/24 22:10:54 vixie Exp $";
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#endif
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <arpa/nameser.h>
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#include <errno.h>
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#include <resolv.h>
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#include <string.h>
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/* Data. */
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static char digits[] = "0123456789";
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/* Forward. */
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static int special(int);
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static int printable(int);
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static int dn_find(const u_char *, const u_char *,
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const u_char * const *,
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const u_char * const *);
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/* Public. */
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/*
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* ns_name_ntop(src, dst, dstsiz)
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* Convert an encoded domain name to printable ascii as per RFC1035.
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* return:
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* Number of bytes written to buffer, or -1 (with errno set)
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* notes:
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* The root is returned as "."
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* All other domains are returned in non absolute form
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*/
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int
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ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) {
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const u_char *cp;
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char *dn, *eom;
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u_char c;
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u_int n;
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cp = src;
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dn = dst;
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eom = dst + dstsiz;
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while ((n = *cp++) != 0) {
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if ((n & NS_CMPRSFLGS) != 0) {
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/* Some kind of compression pointer. */
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errno = EMSGSIZE;
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return (-1);
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}
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if (dn != dst) {
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if (dn >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*dn++ = '.';
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}
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if (dn + n >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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for ((void)NULL; n > 0; n--) {
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c = *cp++;
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if (special(c)) {
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if (dn + 1 >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*dn++ = '\\';
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*dn++ = (char)c;
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} else if (!printable(c)) {
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if (dn + 3 >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*dn++ = '\\';
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*dn++ = digits[c / 100];
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*dn++ = digits[(c % 100) / 10];
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*dn++ = digits[c % 10];
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} else {
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if (dn >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*dn++ = (char)c;
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}
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}
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}
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if (dn == dst) {
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if (dn >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*dn++ = '.';
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}
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if (dn >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*dn++ = '\0';
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return (dn - dst);
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}
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/*
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* ns_name_pton(src, dst, dstsiz)
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* Convert a ascii string into an encoded domain name as per RFC1035.
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* return:
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* -1 if it fails
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* 1 if string was fully qualified
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* 0 is string was not fully qualified
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* notes:
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* Enforces label and domain length limits.
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*/
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int
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ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
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u_char *label, *bp, *eom;
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int c, n, escaped;
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char *cp;
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escaped = 0;
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bp = dst;
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eom = dst + dstsiz;
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label = bp++;
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while ((c = *src++) != 0) {
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if (escaped) {
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if ((cp = strchr(digits, c)) != NULL) {
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n = (cp - digits) * 100;
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if ((c = *src++) == 0 ||
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(cp = strchr(digits, c)) == NULL) {
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errno = EMSGSIZE;
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return (-1);
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}
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n += (cp - digits) * 10;
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if ((c = *src++) == 0 ||
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(cp = strchr(digits, c)) == NULL) {
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errno = EMSGSIZE;
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return (-1);
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}
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n += (cp - digits);
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if (n > 255) {
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errno = EMSGSIZE;
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return (-1);
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}
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c = n;
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}
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escaped = 0;
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} else if (c == '\\') {
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escaped = 1;
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continue;
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} else if (c == '.') {
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c = (bp - label - 1);
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if ((c & NS_CMPRSFLGS) != 0) { /* Label too big. */
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errno = EMSGSIZE;
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return (-1);
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}
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if (label >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*label = c;
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/* Fully qualified ? */
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if (*src == '\0') {
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if (c != 0) {
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if (bp >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*bp++ = '\0';
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}
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if ((bp - dst) > MAXCDNAME) {
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errno = EMSGSIZE;
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return (-1);
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}
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return (1);
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}
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if (c == 0) {
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errno = EMSGSIZE;
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return (-1);
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}
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label = bp++;
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continue;
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}
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if (bp >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*bp++ = (u_char)c;
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}
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c = (bp - label - 1);
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if ((c & NS_CMPRSFLGS) != 0) { /* Label too big. */
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errno = EMSGSIZE;
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return (-1);
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}
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if (label >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*label = c;
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if (c != 0) {
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if (bp >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*bp++ = 0;
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}
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if ((bp - dst) > MAXCDNAME) { /* src too big */
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errno = EMSGSIZE;
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return (-1);
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}
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return (0);
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}
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/*
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* ns_name_unpack(msg, eom, src, dst, dstsiz)
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* Unpack a domain name from a message, source may be compressed.
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* return:
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* -1 if it fails, or consumed octets if it succeeds.
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*/
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int
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ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
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u_char *dst, size_t dstsiz)
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{
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const u_char *srcp, *dstlim;
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u_char *dstp;
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int n, c, len, checked;
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len = -1;
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checked = 0;
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dstp = dst;
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srcp = src;
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dstlim = dst + dstsiz;
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if (srcp < msg || srcp >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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/* Fetch next label in domain name. */
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while ((n = *srcp++) != 0) {
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/* Check for indirection. */
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switch (n & NS_CMPRSFLGS) {
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case 0:
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/* Limit checks. */
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if (dstp + n + 1 >= dstlim || srcp + n >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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checked += n + 1;
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*dstp++ = n;
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memcpy(dstp, srcp, n);
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dstp += n;
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srcp += n;
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break;
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case NS_CMPRSFLGS:
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if (srcp >= eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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if (len < 0)
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len = srcp - src + 1;
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srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
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if (srcp < msg || srcp >= eom) { /* Out of range. */
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errno = EMSGSIZE;
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return (-1);
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}
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checked += 2;
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/*
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* Check for loops in the compressed name;
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* if we've looked at the whole message,
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* there must be a loop.
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*/
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if (checked >= eom - msg) {
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errno = EMSGSIZE;
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return (-1);
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}
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break;
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default:
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errno = EMSGSIZE;
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return (-1); /* flag error */
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}
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}
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*dstp = '\0';
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if (len < 0)
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len = srcp - src;
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return (len);
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}
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/*
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* ns_name_pack(src, dst, dstsiz, dnptrs, lastdnptr)
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* Pack domain name 'domain' into 'comp_dn'.
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* return:
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* Size of the compressed name, or -1.
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* notes:
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* 'dnptrs' is an array of pointers to previous compressed names.
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* dnptrs[0] is a pointer to the beginning of the message. The array
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* ends with NULL.
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* 'lastdnptr' is a pointer to the end of the array pointed to
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* by 'dnptrs'.
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* Side effects:
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* The list of pointers in dnptrs is updated for labels inserted into
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* the message as we compress the name. If 'dnptr' is NULL, we don't
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* try to compress names. If 'lastdnptr' is NULL, we don't update the
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* list.
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*/
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int
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ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
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const u_char **dnptrs, const u_char **lastdnptr)
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{
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u_char *dstp;
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const u_char **cpp, **lpp, *eob, *msg;
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const u_char *srcp;
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int n, l;
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srcp = src;
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dstp = dst;
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eob = dstp + dstsiz;
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lpp = cpp = NULL;
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if (dnptrs != NULL) {
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if ((msg = *dnptrs++) != NULL) {
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for (cpp = dnptrs; *cpp != NULL; cpp++)
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(void)NULL;
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lpp = cpp; /* end of list to search */
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}
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} else
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msg = NULL;
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/* make sure the domain we are about to add is legal */
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l = 0;
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do {
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n = *srcp;
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if ((n & NS_CMPRSFLGS) != 0) {
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errno = EMSGSIZE;
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return (-1);
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}
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l += n + 1;
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if (l > MAXCDNAME) {
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errno = EMSGSIZE;
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return (-1);
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}
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srcp += n + 1;
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} while (n != 0);
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srcp = src;
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do {
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/* Look to see if we can use pointers. */
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n = *srcp;
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if (n != 0 && msg != NULL) {
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l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
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(const u_char * const *)lpp);
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if (l >= 0) {
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if (dstp + 1 >= eob) {
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errno = EMSGSIZE;
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return (-1);
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}
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*dstp++ = (l >> 8) | NS_CMPRSFLGS;
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*dstp++ = l % 256;
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return (dstp - dst);
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}
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/* Not found, save it. */
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if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
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(dstp - msg) < 0x4000) {
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*cpp++ = dstp;
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*cpp = NULL;
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}
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}
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/* copy label to buffer */
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if (n & NS_CMPRSFLGS) { /* Should not happen. */
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errno = EMSGSIZE;
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return (-1);
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}
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if (dstp + 1 + n >= eob) {
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errno = EMSGSIZE;
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return (-1);
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}
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memcpy(dstp, srcp, n + 1);
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srcp += n + 1;
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dstp += n + 1;
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} while (n != 0);
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if (dstp > eob) {
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if (msg != NULL)
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*lpp = NULL;
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errno = EMSGSIZE;
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return (-1);
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}
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return (dstp - dst);
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}
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/*
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* ns_name_uncompress(msg, eom, src, dst, dstsiz)
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* Expand compressed domain name to presentation format.
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* return:
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* Number of bytes read out of `src', or -1 (with errno set).
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* note:
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* Root domain returns as "." not "".
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*/
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int
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ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
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char *dst, size_t dstsiz)
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{
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u_char tmp[NS_MAXCDNAME];
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int n;
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if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
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return (-1);
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if (ns_name_ntop(tmp, dst, dstsiz) == -1)
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return (-1);
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return (n);
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}
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/*
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* ns_name_compress(src, dst, dstsiz, dnptrs, lastdnptr)
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* Compress a domain name into wire format, using compression pointers.
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* return:
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* Number of bytes consumed in `dst' or -1 (with errno set).
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* notes:
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* 'dnptrs' is an array of pointers to previous compressed names.
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* dnptrs[0] is a pointer to the beginning of the message.
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* The list ends with NULL. 'lastdnptr' is a pointer to the end of the
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* array pointed to by 'dnptrs'. Side effect is to update the list of
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* pointers for labels inserted into the message as we compress the name.
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* If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
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* is NULL, we don't update the list.
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*/
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int
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ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
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const u_char **dnptrs, const u_char **lastdnptr)
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{
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u_char tmp[NS_MAXCDNAME];
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if (ns_name_pton(src, tmp, sizeof tmp) == -1)
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return (-1);
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return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
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}
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/*
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* ns_name_skip(ptrptr, eom)
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* Advance *ptrptr to skip over the compressed name it points at.
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* return:
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* 0 on success, -1 (with errno set) on failure.
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*/
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int
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ns_name_skip(const u_char **ptrptr, const u_char *eom) {
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const u_char *cp;
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u_int n;
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cp = *ptrptr;
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while (cp < eom && (n = *cp++) != 0) {
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/* Check for indirection. */
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switch (n & NS_CMPRSFLGS) {
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case 0: /* normal case, n == len */
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cp += n;
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continue;
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case NS_CMPRSFLGS: /* indirection */
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cp++;
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break;
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default: /* illegal type */
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errno = EMSGSIZE;
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return (-1);
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}
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break;
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}
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if (cp > eom) {
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errno = EMSGSIZE;
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return (-1);
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}
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*ptrptr = cp;
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return (0);
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}
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/* Private. */
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/*
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* special(ch)
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* Thinking in noninternationalized USASCII (per the DNS spec),
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* is this characted special ("in need of quoting") ?
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* return:
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* boolean.
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*/
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static int
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special(int ch) {
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switch (ch) {
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case 0x22: /* '"' */
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case 0x2E: /* '.' */
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case 0x3B: /* ';' */
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case 0x5C: /* '\\' */
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/* Special modifiers in zone files. */
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case 0x40: /* '@' */
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case 0x24: /* '$' */
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return (1);
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default:
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return (0);
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}
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}
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/*
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* printable(ch)
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* Thinking in noninternationalized USASCII (per the DNS spec),
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* is this character visible and not a space when printed ?
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* return:
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* boolean.
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*/
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static int
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printable(int ch) {
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return (ch > 0x20 && ch < 0x7f);
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}
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/*
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* Thinking in noninternationalized USASCII (per the DNS spec),
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* convert this character to lower case if it's upper case.
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*/
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static int
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mklower(int ch) {
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if (ch >= 0x41 && ch <= 0x5A)
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return (ch + 0x20);
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return (ch);
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}
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/*
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* dn_find(domain, msg, dnptrs, lastdnptr)
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* Search for the counted-label name in an array of compressed names.
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* return:
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* offset from msg if found, or -1.
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* notes:
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* dnptrs is the pointer to the first name on the list,
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* not the pointer to the start of the message.
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*/
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static int
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dn_find(const u_char *domain, const u_char *msg,
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const u_char * const *dnptrs,
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const u_char * const *lastdnptr)
|
|
{
|
|
const u_char *dn, *cp, *sp;
|
|
const u_char * const *cpp;
|
|
u_int n;
|
|
|
|
for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
|
|
dn = domain;
|
|
sp = cp = *cpp;
|
|
while ((n = *cp++) != 0) {
|
|
/*
|
|
* check for indirection
|
|
*/
|
|
switch (n & NS_CMPRSFLGS) {
|
|
case 0: /* normal case, n == len */
|
|
if (n != *dn++)
|
|
goto next;
|
|
for ((void)NULL; n > 0; n--)
|
|
if (mklower(*dn++) != mklower(*cp++))
|
|
goto next;
|
|
/* Is next root for both ? */
|
|
if (*dn == '\0' && *cp == '\0')
|
|
return (sp - msg);
|
|
if (*dn)
|
|
continue;
|
|
goto next;
|
|
|
|
case NS_CMPRSFLGS: /* indirection */
|
|
cp = msg + (((n & 0x3f) << 8) | *cp);
|
|
break;
|
|
|
|
default: /* illegal type */
|
|
errno = EMSGSIZE;
|
|
return (-1);
|
|
}
|
|
}
|
|
next: ;
|
|
}
|
|
errno = ENOENT;
|
|
return (-1);
|
|
}
|