ares_init.c

      val = try_option(p, q, "retry:");
      if (val && channel->tries == -1)
        channel->tries = atoi(val);
      p = q;
      while (isspace((unsigned char)*p))
        p++;
    }

  return ARES_SUCCESS;
}

#ifndef WIN32
static char *try_config(char *s, const char *opt)
{
  size_t len;

  len = strlen(opt);
  if (strncmp(s, opt, len) != 0 || !isspace((unsigned char)s[len]))
    return NULL;
  s += len;
  while (isspace((unsigned char)*s))
    s++;
  return s;
}

#endif

static const char *try_option(const char *p, const char *q, const char *opt)
{
  size_t len = strlen(opt);
  return ((size_t)(q - p) > len && !strncmp(p, opt, len)) ? &p[len] : NULL;
}

#ifndef WIN32
static int sortlist_alloc(struct apattern **sortlist, int *nsort,
                          struct apattern *pat)
{
  struct apattern *newsort;
  newsort = realloc(*sortlist, (*nsort + 1) * sizeof(struct apattern));
  if (!newsort)
    return 0;
  newsort[*nsort] = *pat;
  *sortlist = newsort;
  (*nsort)++;
  return 1;
}

static int ip_addr(const char *ipbuf, int len, struct in_addr *addr)
{

  /* Four octets and three periods yields at most 15 characters. */
  if (len > 15)
    return -1;

  addr->s_addr = inet_addr(ipbuf);
  if (addr->s_addr == INADDR_NONE && strcmp(ipbuf, "255.255.255.255") != 0)
    return -1;
  return 0;
}

static void natural_mask(struct apattern *pat)
{
  struct in_addr addr;

  /* Store a host-byte-order copy of pat in a struct in_addr.  Icky,
   * but portable.
   */
  addr.s_addr = ntohl(pat->addr.addr4.s_addr);

  /* This is out of date in the CIDR world, but some people might
   * still rely on it.
   */
  if (IN_CLASSA(addr.s_addr))
    pat->mask.addr.addr4.s_addr = htonl(IN_CLASSA_NET);
  else if (IN_CLASSB(addr.s_addr))
    pat->mask.addr.addr4.s_addr = htonl(IN_CLASSB_NET);
  else
    pat->mask.addr.addr4.s_addr = htonl(IN_CLASSC_NET);
}
#endif