/* Domain name processing functions.

   Copyright (C) 1995-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   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/>.  */

/*

 * Copyright (c) 1985, 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.

 */

/*

 * Portions Copyright (c) 1993 by Digital Equipment Corporation.

 *

 * 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, and that

 * the name of Digital Equipment Corporation not be used in advertising or

 * publicity pertaining to distribution of the document or software without

 * specific, written prior permission.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL

 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT

 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL

 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR

 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS

 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS

 * SOFTWARE.

 */

/*

 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.

 *

 * 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.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS

 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE

 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL

 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR

 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS

 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS

 * SOFTWARE.

 */

#include <sys/types.h>

#include <sys/param.h>

#include <netinet/in.h>

#include <arpa/nameser.h>

#include <ctype.h>

#include <resolv.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

/*

 * Expand compressed domain name 'comp_dn' to full domain name.

 * 'msg' is a pointer to the beginning of the message,

 * 'eomorig' points to the first location after the message,

 * 'exp_dn' is a pointer to a buffer of size 'length' for the result.

 * Return size of compressed name or -1 if there was an error.

 */

int

dn_expand(const u_char *msg, const u_char *eom, const u_char *src,

	  char *dst, int dstsiz)

{

	int n = ns_name_uncompress(msg, eom, src, dst, (size_t)dstsiz);

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

		dst[0] = '\0';

	return (n);

}

libresolv_hidden_def (dn_expand)

/*

 * Pack domain name 'exp_dn' in presentation form into 'comp_dn'.

 * Return the size of the compressed name or -1.

 * 'length' is the size of the array pointed to by 'comp_dn'.

 */

int

dn_comp(const char *src, u_char *dst, int dstsiz,

	u_char **dnptrs, u_char **lastdnptr)

{

	return (ns_name_compress(src, dst, (size_t)dstsiz,

				 (const u_char **)dnptrs,

				 (const u_char **)lastdnptr));

}

libresolv_hidden_def (dn_comp)

/*

 * Skip over a compressed domain name. Return the size or -1.

 */

int

dn_skipname(const u_char *ptr, const u_char *eom) {

	const u_char *saveptr = ptr;

	if (ns_name_skip(&ptr, eom) == -1)

		return (-1);

	return (ptr - saveptr);

}

libresolv_hidden_def (dn_skipname)

/* Return true if the string consists of printable ASCII characters

   only.  */

static bool

printable_string (const char *dn)

{

  while (true)

    {

      char ch = *dn;

      if (ch == '\0')

	return true;

      if (ch <= ' ' || ch > '~')

	return false;

      ++dn;

    }

}

/* Return true if DN points to a name consisting only of [0-9a-zA-Z_-]

   characters.  DN must be in DNS wire format, without

   compression.  */

static bool

binary_hnok (const unsigned char *dn)

{

  while (true)

    {

      size_t label_length = *dn;

      if (label_length == 0)

	break;

      ++dn;

      const unsigned char *label_end = dn + label_length;

      do

	{

	  unsigned char ch = *dn;

	  if (!(('0' <= ch && ch <= '9')

		|| ('A' <= ch && ch <= 'Z')

		|| ('a' <= ch && ch <= 'z')

		|| ch == '-' || ch == '_'))

	    return false;

	  ++dn;

	}

      while (dn < label_end);

    }

  return true;

}

/* Return true if the binary domain name has a first labels which

   starts with '-'.  */

static inline bool

binary_leading_dash (const unsigned char *dn)

{

  return dn[0] > 0 && dn[1] == '-';

}

/* Return 1 if res_hnok is a valid host name.  Labels must only

   contain [0-9a-zA-Z_-] characters, and the name must not start with

   a '-'.  The latter is to avoid confusion with program options.  */

int

res_hnok (const char *dn)

{

  unsigned char buf[NS_MAXCDNAME];

  if (!printable_string (dn)

      || ns_name_pton (dn, buf, sizeof (buf)) < 0

      || binary_leading_dash (buf))

    return 0;

  return binary_hnok (buf);

}

libresolv_hidden_def (res_hnok)

/* Hostname-like (A, MX, WKS) owners can have "*" as their first label

   but must otherwise be as a host name.  */

int

res_ownok (const char *dn)

{

  unsigned char buf[NS_MAXCDNAME];

  if (!printable_string (dn)

      || ns_name_pton (dn, buf, sizeof (buf)) < 0

      || binary_leading_dash (buf))

    return 0;

  if (buf[0] == 1 && buf [1] == '*')

    /* Skip over the leading "*." part.  */

    return binary_hnok (buf + 2);

  else

    return binary_hnok (buf);

}

/* SOA RNAMEs and RP RNAMEs can have any byte in their first label,

   but the rest of the name has to look like a host name.  */

int

res_mailok (const char *dn)

{

  unsigned char buf[NS_MAXCDNAME];

  if (!printable_string (dn)

      || ns_name_pton (dn, buf, sizeof (buf)) < 0)

    return 0;

  unsigned char label_length = buf[0];

  /* "." is a valid missing representation */

  if (label_length == 0)

    return 1;

  /* Skip over the first label.  */

  unsigned char *tail = buf + 1 + label_length;

  if (*tail == 0)

    /* More than one label is required (except for ".").  */

    return 0;

  return binary_hnok (tail);

}

/* Return 1 if DN is a syntactically valid domain name.  Empty names

   are accepted.  */

int

res_dnok (const char *dn)

{

  unsigned char buf[NS_MAXCDNAME];

  return printable_string (dn) && ns_name_pton (dn, buf, sizeof (buf)) >= 0;

}

libresolv_hidden_def (res_dnok)

/*

 * This module must export the following externally-visible symbols:

 *	___putlong

 *	___putshort

 *	__getlong

 *	__getshort

 * Note that one _ comes from C and the others come from us.

 */

void __putlong(uint32_t src, u_char *dst) { ns_put32(src, dst); }

libresolv_hidden_def (__putlong)

void __putshort(uint16_t src, u_char *dst) { ns_put16(src, dst); }

libresolv_hidden_def (__putshort)

uint32_t _getlong(const u_char *src) { return (ns_get32(src)); }

uint16_t _getshort(const u_char *src) { return (ns_get16(src)); }

#include <shlib-compat.h>

#if SHLIB_COMPAT(libresolv, GLIBC_2_0, GLIBC_2_2)

# undef dn_expand

weak_alias (__dn_expand, dn_expand);

#endif