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3rdparty/c-ares-1.18.1/src/lib/ares_expand_string.c 1.76 KB
73ef4ff3   Hu Chunming   提交三方库
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  /* Copyright 1998 by the Massachusetts Institute of Technology.
   *
   * Permission to use, copy, modify, and distribute this
   * software and its documentation for any purpose and without
   * fee is hereby granted, provided that the above copyright
   * notice appear in all copies and that both that copyright
   * notice and this permission notice appear in supporting
   * documentation, and that the name of M.I.T. not be used in
   * advertising or publicity pertaining to distribution of the
   * software without specific, written prior permission.
   * M.I.T. makes no representations about the suitability of
   * this software for any purpose.  It is provided "as is"
   * without express or implied warranty.
   */
  
  #include "ares_setup.h"
  
  #ifdef HAVE_NETINET_IN_H
  #  include <netinet/in.h>
  #endif
  
  #include "ares_nameser.h"
  
  #include "ares.h"
  #include "ares_private.h" /* for the memdebug */
  
  /* Simply decodes a length-encoded character string. The first byte of the
   * input is the length of the string to be returned and the bytes thereafter
   * are the characters of the string. The returned result will be NULL
   * terminated.
   */
  int ares_expand_string(const unsigned char *encoded,
                         const unsigned char *abuf,
                         int alen,
                         unsigned char **s,
                         long *enclen)
  {
    unsigned char *q;
    union {
      ares_ssize_t sig;
       size_t uns;
    } elen;
  
    if (encoded == abuf+alen)
      return ARES_EBADSTR;
  
    elen.uns = *encoded;
    if (encoded+elen.sig+1 > abuf+alen)
      return ARES_EBADSTR;
  
    encoded++;
  
    *s = ares_malloc(elen.uns+1);
    if (*s == NULL)
      return ARES_ENOMEM;
    q = *s;
    strncpy((char *)q, (char *)encoded, elen.uns);
    q[elen.uns] = '\0';
  
    *s = q;
  
    *enclen = (long)(elen.sig+1);
  
    return ARES_SUCCESS;
  }