/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 ***************************************************************************/

#include "../curl_setup.h"

#if defined(USE_OPENSSL) || defined(USE_SCHANNEL)

/* these backends use functions from this file */

#ifdef HAVE_NETINET_IN_H

#include <netinet/in.h>

#endif

#ifdef HAVE_NETINET_IN6_H

#include <netinet/in6.h>

#endif

#include "../curl_memrchr.h"

#include "hostcheck.h"

#include "../hostip.h"

/* check the two input strings with given length, but do not

   assume they end in nul-bytes */

static bool pmatch(const char *hostname, size_t hostlen,

                   const char *pattern, size_t patternlen)

{

  if(hostlen != patternlen)

    return FALSE;

  return curl_strnequal(hostname, pattern, hostlen);

}

/*

 * Match a hostname against a wildcard pattern.

 * E.g.

 *  "foo.host.com" matches "*.host.com".

 *

 * We use the matching rule described in RFC6125, section 6.4.3.

 * https://datatracker.ietf.org/doc/html/rfc6125#section-6.4.3

 *

 * In addition: ignore trailing dots in the hostnames and wildcards, so that

 * the names are used normalized. This is what the browsers do.

 *

 * Do not allow wildcard matching on IP numbers. There are apparently

 * certificates being used with an IP address in the CN field, thus making no

 * apparent distinction between a name and an IP. We need to detect the use of

 * an IP address and not wildcard match on such names.

 *

 * Only match on "*" being used for the leftmost label, not "a*", "a*b" nor

 * "*b".

 *

 * Return TRUE on a match. FALSE if not.

 *

 * @unittest: 1397

 */

static bool hostmatch(const char *hostname,

                      size_t hostlen,

                      const char *pattern,

                      size_t patternlen)

{

  const char *pattern_label_end;

  DEBUGASSERT(pattern);

  DEBUGASSERT(patternlen);

  DEBUGASSERT(hostname);

  DEBUGASSERT(hostlen);

  /* normalize pattern and hostname by stripping off trailing dots */

  if(hostname[hostlen - 1] == '.')

    hostlen--;

  if(pattern[patternlen - 1] == '.')

    patternlen--;

  if(strncmp(pattern, "*.", 2))

    return pmatch(hostname, hostlen, pattern, patternlen);

  /* detect host as IP address or starting with a dot and fail if so */

  else if(Curl_host_is_ipnum(hostname) || (hostname[0] == '.'))

    return FALSE;

  /* We require at least 2 dots in the pattern to avoid too wide wildcard

     match. */

  pattern_label_end = memchr(pattern, '.', patternlen);

  if(!pattern_label_end ||

     (memrchr(pattern, '.', patternlen) == pattern_label_end))

    return pmatch(hostname, hostlen, pattern, patternlen);

  else {

    const char *hostname_label_end = memchr(hostname, '.', hostlen);

    if(hostname_label_end) {

      size_t skiphost = hostname_label_end - hostname;

      size_t skiplen = pattern_label_end - pattern;

      return pmatch(hostname_label_end, hostlen - skiphost,

                    pattern_label_end, patternlen - skiplen);

    }

  }

  return FALSE;

}

/*

 * Curl_cert_hostcheck() returns TRUE if a match and FALSE if not.

 */

bool Curl_cert_hostcheck(const char *match, size_t matchlen,

                         const char *hostname, size_t hostlen)

{

  if(match && *match && hostname && *hostname)

    return hostmatch(hostname, hostlen, match, matchlen);

  return FALSE;

}

#endif /* USE_OPENSSL || USE_SCHANNEL */