/* Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

/* Parts of this file are plain copies of the file `getnetnamadr.c' from

   the bind package and it has the following copyright.  */

/* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro

 *      Dep. Matematica Universidade de Coimbra, Portugal, Europe

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 */

/*

 * Copyright (c) 1983, 1993

 *      The Regents of the University of California.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 4. Neither the name of the University nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 */

#include <ctype.h>

#include <errno.h>

#include <netdb.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <stdint.h>

#include <stddef.h>

#include "nsswitch.h"

#include <arpa/inet.h>

#include <arpa/nameser.h>

#include <resolv/resolv-internal.h>

#include <resolv/resolv_context.h>

/* Maximum number of aliases we allow.  */

#define MAX_NR_ALIASES	48

#if PACKETSZ > 65536

# define MAXPACKET	PACKETSZ

#else

# define MAXPACKET	65536

#endif

typedef enum

{

  BYADDR,

  BYNAME

} lookup_method;

/* We need this time later.  */

typedef union querybuf

{

  HEADER hdr;

  u_char buf[MAXPACKET];

} querybuf;

/* Prototypes for local functions.  */

static enum nss_status getanswer_r (const querybuf *answer, int anslen,

				    struct netent *result, char *buffer,

				    size_t buflen, int *errnop, int *h_errnop,

				    lookup_method net_i);

enum nss_status

_nss_dns_getnetbyname_r (const char *name, struct netent *result,

			 char *buffer, size_t buflen, int *errnop,

			 int *herrnop)

{

  /* Return entry for network with NAME.  */

  union

  {

    querybuf *buf;

    u_char *ptr;

  } net_buffer;

  querybuf *orig_net_buffer;

  int anslen;

  enum nss_status status;

  struct resolv_context *ctx = __resolv_context_get ();

  if (ctx == NULL)

    {

      *errnop = errno;

      *herrnop = NETDB_INTERNAL;

      return NSS_STATUS_UNAVAIL;

    }

  net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);

  anslen = __res_context_search

    (ctx, name, C_IN, T_PTR, net_buffer.buf->buf,

     1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);

  if (anslen < 0)

    {

      /* Nothing found.  */

      *errnop = errno;

      if (net_buffer.buf != orig_net_buffer)

	free (net_buffer.buf);

      __resolv_context_put (ctx);

      return (errno == ECONNREFUSED

	      || errno == EPFNOSUPPORT

	      || errno == EAFNOSUPPORT)

	? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;

    }

  status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,

			errnop, herrnop, BYNAME);

  if (net_buffer.buf != orig_net_buffer)

    free (net_buffer.buf);

  __resolv_context_put (ctx);

  return status;

}

enum nss_status

_nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,

			 char *buffer, size_t buflen, int *errnop,

			 int *herrnop)

{

  /* Return entry for network with NAME.  */

  enum nss_status status;

  union

  {

    querybuf *buf;

    u_char *ptr;

  } net_buffer;

  querybuf *orig_net_buffer;

  unsigned int net_bytes[4];

  char qbuf[MAXDNAME];

  int cnt, anslen;

  uint32_t net2;

  int olderr = errno;

  /* No net address lookup for IPv6 yet.  */

  if (type != AF_INET)

    return NSS_STATUS_UNAVAIL;

  struct resolv_context *ctx = __resolv_context_get ();

  if (ctx == NULL)

    {

      *errnop = errno;

      *herrnop = NETDB_INTERNAL;

      return NSS_STATUS_UNAVAIL;

    }

  net2 = (uint32_t) net;

  for (cnt = 4; net2 != 0; net2 >>= 8)

    net_bytes[--cnt] = net2 & 0xff;

  switch (cnt)

    {

    case 3:

      /* Class A network.  */

      sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);

      break;

    case 2:

      /* Class B network.  */

      sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);

      break;

    case 1:

      /* Class C network.  */

      sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],

	       net_bytes[1]);

      break;

    case 0:

      /* Class D - E network.  */

      sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],

	       net_bytes[1], net_bytes[0]);

      break;

    }

  net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);

  anslen = __res_context_query (ctx, qbuf, C_IN, T_PTR, net_buffer.buf->buf,

				1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);

  if (anslen < 0)

    {

      /* Nothing found.  */

      int err = errno;

      __set_errno (olderr);

      if (net_buffer.buf != orig_net_buffer)

	free (net_buffer.buf);

      __resolv_context_put (ctx);

      return (err == ECONNREFUSED

	      || err == EPFNOSUPPORT

	      || err == EAFNOSUPPORT)

	? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;

    }

  status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,

			errnop, herrnop, BYADDR);

  if (net_buffer.buf != orig_net_buffer)

    free (net_buffer.buf);

  if (status == NSS_STATUS_SUCCESS)

    {

      /* Strip trailing zeros.  */

      unsigned int u_net = net;	/* Maybe net should be unsigned?  */

      while ((u_net & 0xff) == 0 && u_net != 0)

	u_net >>= 8;

      result->n_net = u_net;

    }

  __resolv_context_put (ctx);

  return status;

}

static enum nss_status

getanswer_r (const querybuf *answer, int anslen, struct netent *result,

	     char *buffer, size_t buflen, int *errnop, int *h_errnop,

	     lookup_method net_i)

{

  /*

   * Find first satisfactory answer

   *

   *      answer --> +------------+  ( MESSAGE )

   *                 |   Header   |

   *                 +------------+

   *                 |  Question  | the question for the name server

   *                 +------------+

   *                 |   Answer   | RRs answering the question

   *                 +------------+

   *                 | Authority  | RRs pointing toward an authority

   *                 | Additional | RRs holding additional information

   *                 +------------+

   */

  struct net_data

  {

    char *aliases[MAX_NR_ALIASES];

    char linebuffer[0];

  } *net_data;

  uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct net_data);

  buffer += pad;

  if (__glibc_unlikely (buflen < sizeof (*net_data) + pad))

    {

      /* The buffer is too small.  */

    too_small:

      *errnop = ERANGE;

      *h_errnop = NETDB_INTERNAL;

      return NSS_STATUS_TRYAGAIN;

    }

  buflen -= pad;

  net_data = (struct net_data *) buffer;

  int linebuflen = buflen - offsetof (struct net_data, linebuffer);

  if (buflen - offsetof (struct net_data, linebuffer) != linebuflen)

    linebuflen = INT_MAX;

  const unsigned char *end_of_message = &answer->buf[anslen];

  const HEADER *header_pointer = &answer->hdr;

  /* #/records in the answer section.  */

  int answer_count =  ntohs (header_pointer->ancount);

  /* #/entries in the question section.  */

  int question_count = ntohs (header_pointer->qdcount);

  char *bp = net_data->linebuffer;

  const unsigned char *cp = &answer->buf[HFIXEDSZ];

  char **alias_pointer;

  int have_answer;

  u_char packtmp[NS_MAXCDNAME];

  if (question_count == 0)

    {

      /* FIXME: the Sun version uses for host name lookup an additional

	 parameter for pointing to h_errno.  this is missing here.

	 OSF/1 has a per-thread h_errno variable.  */

      if (header_pointer->aa != 0)

	{

	  __set_h_errno (HOST_NOT_FOUND);

	  return NSS_STATUS_NOTFOUND;

	}

      else

	{

	  __set_h_errno (TRY_AGAIN);

	  return NSS_STATUS_TRYAGAIN;

	}

    }

  /* Skip the question part.  */

  while (question_count-- > 0)

    {

      int n = __dn_skipname (cp, end_of_message);

      if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)

       {

         __set_h_errno (NO_RECOVERY);

         return NSS_STATUS_UNAVAIL;

       }

      cp += n + QFIXEDSZ;

    }

  alias_pointer = result->n_aliases = &net_data->aliases[0];

  *alias_pointer = NULL;

  have_answer = 0;

  while (--answer_count >= 0 && cp < end_of_message)

    {

      int n = __ns_name_unpack (answer->buf, end_of_message, cp,

				packtmp, sizeof packtmp);

      if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)

	{

	  if (errno == EMSGSIZE)

	    goto too_small;

	  n = -1;

	}

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

	bp[0] = '\0';

      if (n < 0 || res_dnok (bp) == 0)

	break;

      cp += n;

      if (end_of_message - cp < 10)

	{

	  __set_h_errno (NO_RECOVERY);

	  return NSS_STATUS_UNAVAIL;

	}

      int type, class;

      GETSHORT (type, cp);

      GETSHORT (class, cp);

      cp += INT32SZ;		/* TTL */

      uint16_t rdatalen;

      GETSHORT (rdatalen, cp);

      if (end_of_message - cp < rdatalen)

	{

	  __set_h_errno (NO_RECOVERY);

	  return NSS_STATUS_UNAVAIL;

	}

      if (class == C_IN && type == T_PTR)

	{

	  n = __ns_name_unpack (answer->buf, end_of_message, cp,

				packtmp, sizeof packtmp);

	  if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)

	    {

	      if (errno == EMSGSIZE)

		goto too_small;

	      n = -1;

	    }

	  if (n < 0 || !res_hnok (bp))

	    {

	      /* XXX What does this mean?  The original form from bind

		 returns NULL. Incrementing cp has no effect in any case.

		 What should I return here. ??? */

	      cp += n;

	      return NSS_STATUS_UNAVAIL;

	    }

	  cp += rdatalen;

         if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])

           {

             *alias_pointer++ = bp;

             n = strlen (bp) + 1;

             bp += n;

             linebuflen -= n;

             result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;

             ++have_answer;

           }

	}

      else

	/* Skip over unknown record data.  */

	cp += rdatalen;

    }

  if (have_answer)

    {

      *alias_pointer = NULL;

      switch (net_i)

	{

	case BYADDR:

	  result->n_name = *result->n_aliases++;

	  result->n_net = 0L;

	  return NSS_STATUS_SUCCESS;

	case BYNAME:

	  {

	    char **ap;

	    for (ap = result->n_aliases; *ap != NULL; ++ap)

	      {

		/* Check each alias name for being of the forms:

		   4.3.2.1.in-addr.arpa		= net 1.2.3.4

		   3.2.1.in-addr.arpa		= net 0.1.2.3

		   2.1.in-addr.arpa		= net 0.0.1.2

		   1.in-addr.arpa		= net 0.0.0.1

		*/

		uint32_t val = 0;	/* Accumulator for n_net value.  */

		unsigned int shift = 0; /* Which part we are parsing now.  */

		const char *p = *ap; /* Consuming the string.  */

		do

		  {

		    /* Match the leading 0 or 0[xX] base indicator.  */

		    unsigned int base = 10;

		    if (*p == '0' && p[1] != '.')

		      {

			base = 8;

			++p;

			if (*p == 'x' || *p == 'X')

			  {

			    base = 16;

			    ++p;

			    if (*p == '.')

			      break; /* No digit here.  Give up on alias.  */

			  }

			if (*p == '\0')

			  break;

		      }

		    uint32_t part = 0; /* Accumulates this part's number.  */

		    do

		      {

			if (isdigit (*p) && (*p - '0' < base))

			  part = (part * base) + (*p - '0');

			else if (base == 16 && isxdigit (*p))

			  part = (part << 4) + 10 + (tolower (*p) - 'a');

			++p;

		      } while (*p != '\0' && *p != '.');

		    if (*p != '.')

		      break;	/* Bad form.  Give up on this name.  */

		    /* Install this as the next more significant byte.  */

		    val |= part << shift;

		    shift += 8;

		    ++p;

		    /* If we are out of digits now, there are two cases:

		       1. We are done with digits and now see "in-addr.arpa".

		       2. This is not the droid we are looking for.  */

		    if (!isdigit (*p) && !strcasecmp (p, "in-addr.arpa"))

		      {

			result->n_net = val;

			return NSS_STATUS_SUCCESS;

		      }

		    /* Keep going when we have seen fewer than 4 parts.  */

		  } while (shift < 32);

	      }

	  }

	  break;

	}

    }

  __set_h_errno (TRY_AGAIN);

  return NSS_STATUS_TRYAGAIN;

}