/src/ares/ares_expand_string.c

 1
 2/* Copyright 1998 by the Massachusetts Institute of Technology.
 3 *
 4 * Permission to use, copy, modify, and distribute this
 5 * software and its documentation for any purpose and without
 6 * fee is hereby granted, provided that the above copyright
 7 * notice appear in all copies and that both that copyright
 8 * notice and this permission notice appear in supporting
 9 * documentation, and that the name of M.I.T. not be used in
10 * advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission.
12 * M.I.T. makes no representations about the suitability of
13 * this software for any purpose.  It is provided "as is"
14 * without express or implied warranty.
15 */
16
17#include "ares_setup.h"
18
19#ifdef HAVE_SYS_SOCKET_H
20#  include <sys/socket.h>
21#endif
22#ifdef HAVE_NETINET_IN_H
23#  include <netinet/in.h>
24#endif
25#ifdef HAVE_ARPA_NAMESER_H
26#  include <arpa/nameser.h>
27#else
28#  include "nameser.h"
29#endif
30
31#include <string.h>
32#include <stdlib.h>
33#include "ares.h"
34#include "ares_private.h" /* for the memdebug */
35
36/* Simply decodes a length-encoded character string. The first byte of the
37 * input is the length of the string to be returned and the bytes thereafter
38 * are the characters of the string. The returned result will be NULL
39 * terminated.
40 */
41int ares_expand_string(const unsigned char *encoded,
42                       const unsigned char *abuf,
43                       int alen,
44                       unsigned char **s,
45                       long *enclen)
46{
47  unsigned char *q;
48  union {
49    ssize_t sig;
50     size_t uns;
51  } elen;
52
53  if (encoded == abuf+alen)
54    return ARES_EBADSTR;
55
56  elen.uns = *encoded;
57  if (encoded+elen.sig+1 > abuf+alen)
58    return ARES_EBADSTR;
59
60  encoded++;
61
62  *s = malloc(elen.uns+1);
63  if (*s == NULL)
64    return ARES_ENOMEM;
65  q = *s;
66  strncpy((char *)q, (char *)encoded, elen.uns);
67  q[elen.uns] = '\0';
68
69  *s = q;
70
71  *enclen = (long)(elen.sig+1);
72
73  return ARES_SUCCESS;
74}
75