adig.c

这是国外的resip协议栈

  ares_destroy(channel);
  return 0;
}

static void callback(void *arg, int status, unsigned char *abuf, int alen)
{
  char *name = (char *) arg, *errmem;
  int id, qr, opcode, aa, tc, rd, ra, rcode, i;
  unsigned int qdcount, ancount, nscount, arcount;
  const unsigned char *aptr;

  /* Display the query name if given. */
  if (name)
    printf("Answer for query %s:\n", name);

  /* Display an error message if there was an error, but only stop if
   * we actually didn't get an answer buffer.
   */
  if (status != ARES_SUCCESS)
    {
       printf("%s\n", ares_strerror(status));//, &errmem));
      ares_free_errmem(errmem);
      if (!abuf)
	return;
    }

  /* Won't happen, but check anyway, for safety. */
  if (alen < HFIXEDSZ)
    return;

  /* Parse the answer header. */
  id = DNS_HEADER_QID(abuf);             /* query identification number */
  qr = DNS_HEADER_QR(abuf);              /* query response */
  opcode = DNS_HEADER_OPCODE(abuf);      /* opcode */
  aa = DNS_HEADER_AA(abuf);              /* authoritative answer */
  tc = DNS_HEADER_TC(abuf);              /* truncation */
  rd = DNS_HEADER_RD(abuf);              /* recursion desired */
  ra = DNS_HEADER_RA(abuf);              /* recursion available */
  rcode = DNS_HEADER_RCODE(abuf);        /* response code */
  qdcount = DNS_HEADER_QDCOUNT(abuf);    /* question count */
  ancount = DNS_HEADER_ANCOUNT(abuf);    /* answer record count */
  nscount = DNS_HEADER_NSCOUNT(abuf);    /* name server record count */
  arcount = DNS_HEADER_ARCOUNT(abuf);    /* additional record count */

  /* Display the answer header. */
  printf("id: %d\n", id);
  printf("flags: %s%s%s%s%s\n",
	 qr ? "qr " : "",
	 aa ? "aa " : "",
	 tc ? "tc " : "",
	 rd ? "rd " : "",
	 ra ? "ra " : "");
  printf("opcode: %s\n", opcodes[opcode]);
  printf("rcode: %s\n", rcodes[rcode]);

  /* Display the questions. */
  printf("Questions:\n");
  aptr = abuf + HFIXEDSZ;
  for (i = 0; i < (int)qdcount; i++)
    {
      aptr = display_question(aptr, abuf, alen);
      if (aptr == NULL)
	return;
    }

  /* Display the answers. */
  printf("Answers:\n");
  for (i = 0; i < (int)ancount; i++)
    {
      aptr = display_rr(aptr, abuf, alen);
      if (aptr == NULL)
	return;
    }

  /* Display the NS records. */
  printf("NS records:\n");
  for (i = 0; i < (int)nscount; i++)
    {
      aptr = display_rr(aptr, abuf, alen);
      if (aptr == NULL)
	return;
    }

  /* Display the additional records. */
  printf("Additional records:\n");
  for (i = 0; i < (int)arcount; i++)
    {
      aptr = display_rr(aptr, abuf, alen);
      if (aptr == NULL)
	return;
    }
}

static const unsigned char *display_question(const unsigned char *aptr,
					     const unsigned char *abuf,
					     int alen)
{
  char *name;
  int type, dnsclass, status, len;

  /* Parse the question name. */
  status = ares_expand_name(aptr, abuf, alen, &name, &len);
  if (status != ARES_SUCCESS)
    return NULL;
  aptr += len;

  /* Make sure there's enough data after the name for the fixed part
   * of the question.
   */
  if (aptr + QFIXEDSZ > abuf + alen)
    {
      free(name);
      return NULL;
    }

  /* Parse the question type and class. */
  type = DNS_QUESTION_TYPE(aptr);
  dnsclass = DNS_QUESTION_CLASS(aptr);
  aptr += QFIXEDSZ;

  /* Display the question, in a format sort of similar to how we will
   * display RRs.
   */
  printf("\t%-15s.\t", name);
  if (dnsclass != C_IN)
    printf("\t%s", class_name(dnsclass));
  printf("\t%s\n", type_name(type));
  free(name);
  return aptr;
}

static const unsigned char *display_rr(const unsigned char *aptr,
				       const unsigned char *abuf, int alen)
{
  const unsigned char *p;
  char *name;
  int type, dnsclass, ttl, dlen, status, len;
  struct in_addr addr;

  /* Parse the RR name. */
  status = ares_expand_name(aptr, abuf, alen, &name, &len);
  if (status != ARES_SUCCESS)
    return NULL;
  aptr += len;

  /* Make sure there is enough data after the RR name for the fixed
   * part of the RR.
   */
  if (aptr + RRFIXEDSZ > abuf + alen)
    {
      free(name);
      return NULL;
    }

  /* Parse the fixed part of the RR, and advance to the RR data
   * field. */
  type = DNS_RR_TYPE(aptr);
  dnsclass = DNS_RR_CLASS(aptr);
  ttl = DNS_RR_TTL(aptr);
  dlen = DNS_RR_LEN(aptr);
  aptr += RRFIXEDSZ;
  if (aptr + dlen > abuf + alen)
    {
      free(name);
      return NULL;
    }

  /* Display the RR name, class, and type. */
  printf("\t%-15s.\t%d", name, ttl);
  if (dnsclass != C_IN)
    printf("\t%s", class_name(dnsclass));
  printf("\t%s", type_name(type));
  free(name);

  /* Display the RR data.  Don't touch aptr. */
  switch (type)
    {
    case T_CNAME:
    case T_MB:
    case T_MD:
    case T_MF:
    case T_MG:
    case T_MR:
    case T_NS:
    case T_PTR:
      /* For these types, the RR data is just a domain name. */
      status = ares_expand_name(aptr, abuf, alen, &name, &len);
      if (status != ARES_SUCCESS)
	return NULL;
      printf("\t%s.", name);
      free(name);
      break;

    case T_HINFO:
      /* The RR data is two length-counted character strings. */
      p = aptr;
      len = *p;
      if (p + len + 1 > aptr + dlen)
	return NULL;
      printf("\t%.*s", len, p + 1);
      p += len + 1;
      len = *p;
      if (p + len + 1 > aptr + dlen)
	return NULL;
      printf("\t%.*s", len, p + 1);
      break;

    case T_MINFO:
      /* The RR data is two domain names. */
      p = aptr;
      status = ares_expand_name(p, abuf, alen, &name, &len);
      if (status != ARES_SUCCESS)
	return NULL;
      printf("\t%s.", name);
      free(name);
      p += len;
      status = ares_expand_name(p, abuf, alen, &name, &len);
      if (status != ARES_SUCCESS)
	return NULL;
      printf("\t%s.", name);
      free(name);
      break;

    case T_MX:
      /* The RR data is two bytes giving a preference ordering, and
       * then a domain name.
       */
      if (dlen < 2)
	return NULL;
      printf("\t%d", (aptr[0] << 8) | aptr[1]);
      status = ares_expand_name(aptr + 2, abuf, alen, &name, &len);
      if (status != ARES_SUCCESS)
	return NULL;
      printf("\t%s.", name);
      free(name);
      break;

    case T_SOA:
      /* The RR data is two domain names and then five four-byte
       * numbers giving the serial number and some timeouts.
       */
      p = aptr;
      status = ares_expand_name(p, abuf, alen, &name, &len);
      if (status != ARES_SUCCESS)
	return NULL;
      printf("\t%s.\n", name);
      free(name);
      p += len;
      status = ares_expand_name(p, abuf, alen, &name, &len);
      if (status != ARES_SUCCESS)
	return NULL;
      printf("\t\t\t\t\t\t%s.\n", name);
      free(name);
      p += len;
      if (p + 20 > aptr + dlen)
	return NULL;
      printf("\t\t\t\t\t\t( %d %d %d %d %d )",
	     (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3],
	     (p[4] << 24) | (p[5] << 16) | (p[6] << 8) | p[7],
	     (p[8] << 24) | (p[9] << 16) | (p[10] << 8) | p[11],
	     (p[12] << 24) | (p[13] << 16) | (p[14] << 8) | p[15],
	     (p[16] << 24) | (p[17] << 16) | (p[18] << 8) | p[19]);
      break;

    case T_TXT:
      /* The RR data is one or more length-counted character
       * strings. */
      p = aptr;
      while (p < aptr + dlen)
	{
	  len = *p;
	  if (p + len + 1 > aptr + dlen)
	    return NULL;
	  printf("\t%.*s", len, p + 1);
	  p += len + 1;
	}
      break;

    case T_A:
      /* The RR data is a four-byte Internet address. */
      if (dlen != 4)
	return NULL;
      memcpy(&addr, aptr, sizeof(struct in_addr));
      printf("\t%s", inet_ntoa(addr));
      break;

    case T_WKS:
      /* Not implemented yet */
      break;

    case T_SRV:
      /* The RR data is three two-byte numbers representing the
       * priority, weight, and port, followed by a domain name.
       */
      
      printf("\t%d", DNS__16BIT(aptr));
      printf(" %d", DNS__16BIT(aptr + 2));
      printf(" %d", DNS__16BIT(aptr + 4));
      
      status = ares_expand_name(aptr + 6, abuf, alen, &name, &len);
      if (status != ARES_SUCCESS)
        return NULL;
      printf("\t%s.", name);
      free(name);
      break;
      
    case T_NAPTR:
      /* The RR data is two two-byte numbers representing the
       * order and preference, followed by three character strings
       * representing flags, services, a regex, and a domain name.
       */

      printf("\t%d", DNS__16BIT(aptr));
      printf(" %d", DNS__16BIT(aptr + 2));

      p = aptr + 4;
      len = *p;
      if (p + len + 1 > aptr + dlen)
        return NULL;
      printf(" %.*s", len, p + 1);
      p += len + 1;
      len = *p;
      if (p + len + 1 > aptr + dlen)
        return NULL;
      printf(" %.*s", len, p + 1);
      p += len + 1;
      len = *p;
      if (p + len + 1 > aptr + dlen)
        return NULL;
      printf(" %.*s", len, p + 1);
      p += len + 1;
      status = ares_expand_name(p, abuf, alen, &name, &len);
      if (status != ARES_SUCCESS)
        return NULL;
      printf("\t%s.", name);
      free(name);
      break;

    default:
      printf("\t[Unknown RR; cannot parse]");
    }
  printf("\n");

  return aptr + dlen;
}

static const char *type_name(int type)
{
  int i;

  for (i = 0; i < ntypes; i++)
    {
      if (types[i].value == type)
	return types[i].name;
    }
  return "(unknown)";
}

static const char *class_name(int dnsclass)
{
  int i;

  for (i = 0; i < nclasses; i++)
    {
      if (classes[i].value == dnsclass)
	return classes[i].name;
    }
  return "(unknown)";
}

static void usage(void)
{
  fprintf(stderr, "usage: adig [-f flag] [-s server] [-c class] "
	  "[-t type] [-p port] name ...\n");
  exit(1);
}