getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype,
	     struct hostent *result, char *buffer, size_t buflen,
	     int *errnop, int *h_errnop, int map, int32_t *ttlp, char **canonp)
{
  struct host_data
  {
    char *aliases[MAX_NR_ALIASES];
    unsigned char host_addr[16];	/* IPv4 or IPv6 */
    char *h_addr_ptrs[0];
  } *host_data;
  int linebuflen;
  const HEADER *hp;
  const u_char *end_of_message, *cp;
  int n, ancount, qdcount;
  int haveanswer, had_error;
  char *bp, **ap, **hap;
  char tbuf[MAXDNAME];
  const char *tname;
  int (*name_ok) (const char *);
  u_char packtmp[NS_MAXCDNAME];
  int have_to_map = 0;
  uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data);
  buffer += pad;
  buflen = buflen > pad ? buflen - pad : 0;
  if (__glibc_unlikely (buflen < sizeof (struct host_data)))
    {
      /* The buffer is too small.  */
    too_small:
      *errnop = ERANGE;
      *h_errnop = NETDB_INTERNAL;
      return NSS_STATUS_TRYAGAIN;
    }
  host_data = (struct host_data *) buffer;
  linebuflen = buflen - sizeof (struct host_data);
  if (buflen - sizeof (struct host_data) != linebuflen)
    linebuflen = INT_MAX;

  tname = qname;
  result->h_name = NULL;
  end_of_message = answer->buf + anslen;
  switch (qtype)
    {
    case T_A:
    case T_AAAA:
      name_ok = res_hnok;
      break;
    case T_PTR:
      name_ok = res_dnok;
      break;
    default:
      *errnop = ENOENT;
      return NSS_STATUS_UNAVAIL;  /* XXX should be abort(); */
    }

  /*
   * find first satisfactory answer
   */
  hp = &answer->hdr;
  ancount = ntohs (hp->ancount);
  qdcount = ntohs (hp->qdcount);
  cp = answer->buf + HFIXEDSZ;
  if (__builtin_expect (qdcount, 1) != 1)
    {
      *h_errnop = NO_RECOVERY;
      return NSS_STATUS_UNAVAIL;
    }
  if (sizeof (struct host_data) + (ancount + 1) * sizeof (char *) >= buflen)
    goto too_small;
  bp = (char *) &host_data->h_addr_ptrs[ancount + 1];
  linebuflen -= (ancount + 1) * sizeof (char *);

  n = __ns_name_unpack (answer->buf, end_of_message, cp,
			packtmp, sizeof packtmp);
  if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
    {
      if (__builtin_expect (errno, 0) == EMSGSIZE)
	goto too_small;

      n = -1;
    }

  if (n > 0 && bp[0] == '.')
    bp[0] = '\0';

  if (__builtin_expect (n < 0 || ((*name_ok) (bp) == 0 && (errno = EBADMSG)),
			0))
    {
      *errnop = errno;
      *h_errnop = NO_RECOVERY;
      return NSS_STATUS_UNAVAIL;
    }
  cp += n + QFIXEDSZ;

  if (qtype == T_A || qtype == T_AAAA)
    {
      /* res_send() has already verified that the query name is the
       * same as the one we sent; this just gets the expanded name
       * (i.e., with the succeeding search-domain tacked on).
       */
      n = strlen (bp) + 1;             /* for the \0 */
      if (n >= MAXHOSTNAMELEN)
	{
	  *h_errnop = NO_RECOVERY;
	  *errnop = ENOENT;
	  return NSS_STATUS_TRYAGAIN;
	}
      result->h_name = bp;
      bp += n;
      linebuflen -= n;
      if (linebuflen < 0)
	goto too_small;
      /* The qname can be abbreviated, but h_name is now absolute. */
      qname = result->h_name;
    }

  ap = host_data->aliases;
  *ap = NULL;
  result->h_aliases = host_data->aliases;
  hap = host_data->h_addr_ptrs;
  *hap = NULL;
  result->h_addr_list = host_data->h_addr_ptrs;
  haveanswer = 0;
  had_error = 0;

  while (ancount-- > 0 && cp < end_of_message && had_error == 0)
    {
      int type, class;

      n = __ns_name_unpack (answer->buf, end_of_message, cp,
			    packtmp, sizeof packtmp);
      if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
	{
	  if (__builtin_expect (errno, 0) == EMSGSIZE)
	    goto too_small;

	  n = -1;
	}

      if (__glibc_unlikely (n < 0 || (*name_ok) (bp) == 0))
	{
	  ++had_error;
	  continue;
	}
      cp += n;				/* name */

      if (__glibc_unlikely (cp + 10 > end_of_message))
	{
	  ++had_error;
	  continue;
	}

      type = __ns_get16 (cp);
      cp += INT16SZ;			/* type */
      class = __ns_get16 (cp);
      cp += INT16SZ;			/* class */
      int32_t ttl = __ns_get32 (cp);
      cp += INT32SZ;			/* TTL */
      n = __ns_get16 (cp);
      cp += INT16SZ;			/* len */

      if (end_of_message - cp < n)
	{
	  /* RDATA extends beyond the end of the packet.  */
	  ++had_error;
	  continue;
	}

      if (__glibc_unlikely (class != C_IN))
	{
	  /* XXX - debug? syslog? */
	  cp += n;
	  continue;			/* XXX - had_error++ ? */
	}

      if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME)
	{
	  /* A CNAME could also have a TTL entry.  */
	  if (ttlp != NULL && ttl < *ttlp)
	      *ttlp = ttl;

	  if (ap >= &host_data->aliases[MAX_NR_ALIASES - 1])
	    continue;
	  n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
	  if (__glibc_unlikely (n < 0 || (*name_ok) (tbuf) == 0))
	    {
	      ++had_error;
	      continue;
	    }
	  cp += n;
	  /* Store alias.  */
	  *ap++ = bp;
	  n = strlen (bp) + 1;		/* For the \0.  */
	  if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
	    {
	      ++had_error;
	      continue;
	    }
	  bp += n;
	  linebuflen -= n;
	  /* Get canonical name.  */
	  n = strlen (tbuf) + 1;	/* For the \0.  */
	  if (__glibc_unlikely (n > linebuflen))
	    goto too_small;
	  if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
	    {
	      ++had_error;
	      continue;
	    }
	  result->h_name = bp;
	  bp = __mempcpy (bp, tbuf, n);	/* Cannot overflow.  */
	  linebuflen -= n;
	  continue;
	}

      if (qtype == T_PTR && type == T_CNAME)
	{
	  /* A CNAME could also have a TTL entry.  */
	  if (ttlp != NULL && ttl < *ttlp)
	      *ttlp = ttl;

	  n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
	  if (__glibc_unlikely (n < 0 || res_dnok (tbuf) == 0))
	    {
	      ++had_error;
	      continue;
	    }
	  cp += n;
	  /* Get canonical name.  */
	  n = strlen (tbuf) + 1;   /* For the \0.  */
	  if (__glibc_unlikely (n > linebuflen))
	    goto too_small;
	  if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
	    {
	      ++had_error;
	      continue;
	    }
	  tname = bp;
	  bp = __mempcpy (bp, tbuf, n);	/* Cannot overflow.  */
	  linebuflen -= n;
	  continue;
	}

      if (type == T_A && qtype == T_AAAA && map)
	have_to_map = 1;
      else if (__glibc_unlikely (type != qtype))
	{
	  cp += n;
	  continue;			/* XXX - had_error++ ? */
	}

      switch (type)
	{
	case T_PTR:
	  if (__glibc_unlikely (strcasecmp (tname, bp) != 0))
	    {
	      cp += n;
	      continue;			/* XXX - had_error++ ? */
	    }

	  n = __ns_name_unpack (answer->buf, end_of_message, cp,
				packtmp, sizeof packtmp);
	  if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
	    {
	      if (__builtin_expect (errno, 0) == EMSGSIZE)
		goto too_small;

	      n = -1;
	    }

	  if (__glibc_unlikely (n < 0 || res_hnok (bp) == 0))
	    {
	      ++had_error;
	      break;
	    }
	  if (ttlp != NULL && ttl < *ttlp)
	      *ttlp = ttl;
	  /* bind would put multiple PTR records as aliases, but we don't do
	     that.  */
	  result->h_name = bp;
	  if (have_to_map)
	    {
	      n = strlen (bp) + 1;	/* for the \0 */
	      if (__glibc_unlikely (n >= MAXHOSTNAMELEN))
		{
		  ++had_error;
		  break;
		}
	      bp += n;
	      linebuflen -= n;
	      if (map_v4v6_hostent (result, &bp, &linebuflen))
		goto too_small;
	    }
	  *h_errnop = NETDB_SUCCESS;
	  return NSS_STATUS_SUCCESS;
	case T_A:
	case T_AAAA:
	  if (__builtin_expect (strcasecmp (result->h_name, bp), 0) != 0)
	    {
	      cp += n;
	      continue;			/* XXX - had_error++ ? */
	    }

	  /* Stop parsing at a record whose length is incorrect.  */
	  if (n != rrtype_to_rdata_length (type))
	    {
	      ++had_error;
	      break;
	    }

	  /* Skip records of the wrong type.  */
	  if (n != result->h_length)
	    {
	      cp += n;
	      continue;
	    }
	  if (!haveanswer)
	    {
	      int nn;

	      /* We compose a single hostent out of the entire chain of
	         entries, so the TTL of the hostent is essentially the lowest
		 TTL in the chain.  */
	      if (ttlp != NULL && ttl < *ttlp)
		*ttlp = ttl;
	      if (canonp != NULL)
		*canonp = bp;
	      result->h_name = bp;
	      nn = strlen (bp) + 1;	/* for the \0 */
	      bp += nn;
	      linebuflen -= nn;
	    }

	  linebuflen -= sizeof (align) - ((u_long) bp % sizeof (align));
	  bp += sizeof (align) - ((u_long) bp % sizeof (align));

	  if (__glibc_unlikely (n > linebuflen))
	    goto too_small;
	  bp = __mempcpy (*hap++ = bp, cp, n);
	  cp += n;
	  linebuflen -= n;
	  break;
	default:
	  abort ();
	}
      if (had_error == 0)
	++haveanswer;
    }

  if (haveanswer > 0)
    {
      *ap = NULL;
      *hap = NULL;
      /*
       * Note: we sort even if host can take only one address
       * in its return structures - should give it the "best"
       * address in that case, not some random one
       */
      if (_res.nsort && haveanswer > 1 && qtype == T_A)
	addrsort (host_data->h_addr_ptrs, haveanswer);

      if (result->h_name == NULL)
	{
	  n = strlen (qname) + 1;	/* For the \0.  */
	  if (n > linebuflen)
	    goto too_small;
	  if (n >= MAXHOSTNAMELEN)
	    goto no_recovery;
	  result->h_name = bp;
	  bp = __mempcpy (bp, qname, n);	/* Cannot overflow.  */
	  linebuflen -= n;
	}

      if (have_to_map)
	if (map_v4v6_hostent (result, &bp, &linebuflen))
	  goto too_small;
      *h_errnop = NETDB_SUCCESS;
      return NSS_STATUS_SUCCESS;
    }
 no_recovery:
  *h_errnop = NO_RECOVERY;
  *errnop = ENOENT;
  /* Special case here: if the resolver sent a result but it only
     contains a CNAME while we are looking for a T_A or T_AAAA record,
     we fail with NOTFOUND instead of TRYAGAIN.  */
  return ((qtype == T_A || qtype == T_AAAA) && ap != host_data->aliases
	   ? NSS_STATUS_NOTFOUND : NSS_STATUS_TRYAGAIN);
}