#include "byte.h"
#include "dnsresolv.h"
#include "ip.h"
#include "stralloc.h"
#include "uint_t.h"

/**
  @file dns_name.c
  @author djb, fefe, feh
  @source ucspi-tcp
  @brief DNS name query (ptr)
*/

static char *q = 0;

int dns_name_packet(stralloc *out, const char *buf, unsigned int len)
{
  unsigned int pos;
  char header[12];
  uint16 numanswers;
  uint16 datalen;

  if (!stralloc_copys(out, "")) return DNS_MEM;

  pos = dns_packet_copy(buf, len, 0, header, 12);
  if (!pos) return DNS_ERR;
  uint16_unpack_big(header + 6, &numanswers);
  pos = dns_packet_skipname(buf, len, pos);
  if (!pos) return DNS_ERR;
  pos += 4;

  while (numanswers--) {
    pos = dns_packet_skipname(buf, len, pos);
    if (!pos) return DNS_ERR;
    pos = dns_packet_copy(buf, len, pos, header, 10);
    if (!pos) return DNS_ERR;
    uint16_unpack_big(header + 8, &datalen);
    if (byte_equal(header, 2, DNS_T_PTR)) {
      if (byte_equal(header + 2, 2, DNS_C_IN)) {
        if (!dns_packet_getname(buf, len, pos, &q)) return DNS_ERR;
        if (dns_domain_todot_cat(out, q) <= 0) return DNS_ERR;
        return 1;
      }
    }
    pos += datalen;
  }

  return 0;
}

int dns_name4(stralloc *out, const char ip[4])
{
  int rc;
  char name[DNS_NAME4_DOMAIN];

  dns_name4_domain(name, ip);
  if (dns_resolve(name, DNS_T_PTR) < 0) return DNS_ERR;
  if ((rc = dns_name_packet(out, dns_resolve_tx.packet, dns_resolve_tx.packetlen)) < 0) return DNS_ERR;
  dns_transmit_free(&dns_resolve_tx);
  dns_domain_free(&q);

  return rc;
}

int dns_name6(stralloc *out, const char ip[16])
{
  int rc;
  char name[DNS_NAME6_DOMAIN];

  dns_name6_domain(name, ip);
  if (dns_resolve(name, DNS_T_PTR) < 0) return DNS_ERR;
  if ((rc = dns_name_packet(out, dns_resolve_tx.packet, dns_resolve_tx.packetlen)) < 0) return DNS_ERR;
  dns_transmit_free(&dns_resolve_tx);
  dns_domain_free(&q);

  return rc;
}

int dns_name(stralloc *out, const char ip[16])
{
  if (ip6_isv4mapped(ip))
    return dns_name4(out, ip + 12);
  else
    return dns_name6(out, ip);
}