src/third_party/curl/hostcheck.cpp

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2015, 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.haxx.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.
 *
 ***************************************************************************/

#include "hostcheck.hpp"

#include <stdlib.h>
#include <string.h>

/* Portable, consistent toupper (remember EBCDIC). Do not use toupper() because
   its behavior is altered by the current locale. */
static char Curl_raw_toupper(char in)
{
#if !defined(CURL_DOES_CONVERSIONS)
  if(in >= 'a' && in <= 'z')
    return (char)('A' + in - 'a');
#else
  switch (in) {
  case 'a':
    return 'A';
  case 'b':
    return 'B';
  case 'c':
    return 'C';
  case 'd':
    return 'D';
  case 'e':
    return 'E';
  case 'f':
    return 'F';
  case 'g':
    return 'G';
  case 'h':
    return 'H';
  case 'i':
    return 'I';
  case 'j':
    return 'J';
  case 'k':
    return 'K';
  case 'l':
    return 'L';
  case 'm':
    return 'M';
  case 'n':
    return 'N';
  case 'o':
    return 'O';
  case 'p':
    return 'P';
  case 'q':
    return 'Q';
  case 'r':
    return 'R';
  case 's':
    return 'S';
  case 't':
    return 'T';
  case 'u':
    return 'U';
  case 'v':
    return 'V';
  case 'w':
    return 'W';
  case 'x':
    return 'X';
  case 'y':
    return 'Y';
  case 'z':
    return 'Z';
  }
#endif

  return in;
}

/*
 * Curl_raw_equal() is for doing "raw" case insensitive strings. This is meant
 * to be locale independent and only compare strings we know are safe for
 * this.  See https://daniel.haxx.se/blog/2008/10/15/strcasecmp-in-turkish/ for
 * some further explanation to why this function is necessary.
 *
 * The function is capable of comparing a-z case insensitively even for
 * non-ascii.
 */

static int Curl_raw_equal(const char *first, const char *second)
{
  while(*first && *second) {
    if(Curl_raw_toupper(*first) != Curl_raw_toupper(*second))
      /* get out of the loop as soon as they don't match */
      break;
    first++;
    second++;
  }
  /* we do the comparison here (possibly again), just to make sure that if the
     loop above is skipped because one of the strings reached zero, we must not
     return this as a successful match */
  return (Curl_raw_toupper(*first) == Curl_raw_toupper(*second));
}

static int Curl_raw_nequal(const char *first, const char *second, size_t max)
{
  while(*first && *second && max) {
    if(Curl_raw_toupper(*first) != Curl_raw_toupper(*second)) {
      break;
    }
    max--;
    first++;
    second++;
  }
  if(0 == max)
    return 1; /* they are equal this far */

  return Curl_raw_toupper(*first) == Curl_raw_toupper(*second);
}

/*
 * 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://tools.ietf.org/html/rfc6125#section-6.4.3
 *
 * In addition: ignore trailing dots in the host names 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.
 *
 * NOTE: hostmatch() gets called with copied buffers so that it can modify the
 * contents at will.
 */

static int hostmatch(const char *hostname, const char *pattern)
{
  const char *pattern_label_end, *pattern_wildcard, *hostname_label_end;
  int wildcard_enabled;
  size_t prefixlen, suffixlen;

  pattern_wildcard = strchr(pattern, '*');
  if(pattern_wildcard == NULL)
    return Curl_raw_equal(pattern, hostname) ?
      CURL_HOST_MATCH : CURL_HOST_NOMATCH;

  /* We require at least 2 dots in pattern to avoid too wide wildcard
     match. */
  wildcard_enabled = 1;
  pattern_label_end = strchr(pattern, '.');
  if(pattern_label_end == NULL || strchr(pattern_label_end+1, '.') == NULL ||
     pattern_wildcard > pattern_label_end ||
     Curl_raw_nequal(pattern, "xn--", 4)) {
    wildcard_enabled = 0;
  }
  if(!wildcard_enabled)
    return Curl_raw_equal(pattern, hostname) ?
      CURL_HOST_MATCH : CURL_HOST_NOMATCH;

  hostname_label_end = strchr(hostname, '.');
  if(hostname_label_end == NULL ||
     !Curl_raw_equal(pattern_label_end, hostname_label_end))
    return CURL_HOST_NOMATCH;

  /* The wildcard must match at least one character, so the left-most
     label of the hostname is at least as large as the left-most label
     of the pattern. */
  if(hostname_label_end - hostname < pattern_label_end - pattern)
    return CURL_HOST_NOMATCH;

  prefixlen = pattern_wildcard - pattern;
  suffixlen = pattern_label_end - (pattern_wildcard+1);
  return Curl_raw_nequal(pattern, hostname, prefixlen) &&
    Curl_raw_nequal(pattern_wildcard+1, hostname_label_end - suffixlen,
                    suffixlen) ?
    CURL_HOST_MATCH : CURL_HOST_NOMATCH;
}

int Curl_cert_hostcheck(const char *match_pattern, const char *hostname)
{
  int res = 0;
  if(!match_pattern || !*match_pattern ||
      !hostname || !*hostname) /* sanity check */
    ;
  else {
    if(hostmatch(hostname , match_pattern) == CURL_HOST_MATCH)
      res= 1;
  }

  return res;
}