text: //
  // ssl/impl/rfc2818_verification.ipp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  #ifndef BOOST_ASIO_SSL_IMPL_RFC2818_VERIFICATION_IPP
  #define BOOST_ASIO_SSL_IMPL_RFC2818_VERIFICATION_IPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include <boost/asio/detail/config.hpp>
  
  #if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
  # include <cctype>
  # include <cstring>
  # include <boost/asio/ip/address.hpp>
  # include <boost/asio/ssl/rfc2818_verification.hpp>
  # include <boost/asio/ssl/detail/openssl_types.hpp>
  #endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace ssl {
  
  #if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
  
  bool rfc2818_verification::operator()(
      bool preverified, verify_context& ctx) const
  {
    using namespace std; // For memcmp.
  
    // Don't bother looking at certificates that have failed pre-verification.
    if (!preverified)
      return false;
  
    // We're only interested in checking the certificate at the end of the chain.
    int depth = X509_STORE_CTX_get_error_depth(ctx.native_handle());
    if (depth > 0)
      return true;
  
    // Try converting the host name to an address. If it is an address then we
    // need to look for an IP address in the certificate rather than a host name.
    boost::system::error_code ec;
    ip::address address = ip::address::from_string(host_, ec);
    bool is_address = !ec;
  
    X509* cert = X509_STORE_CTX_get_current_cert(ctx.native_handle());
  
    // Go through the alternate names in the certificate looking for matching DNS
    // or IP address entries.
    GENERAL_NAMES* gens = static_cast<GENERAL_NAMES*>(
        X509_get_ext_d2i(cert, NID_subject_alt_name, 0, 0));
    for (int i = 0; i < sk_GENERAL_NAME_num(gens); ++i)
    {
      GENERAL_NAME* gen = sk_GENERAL_NAME_value(gens, i);
      if (gen->type == GEN_DNS && !is_address)
      {
        ASN1_IA5STRING* domain = gen->d.dNSName;
        if (domain->type == V_ASN1_IA5STRING && domain->data && domain->length)
        {
          const char* pattern = reinterpret_cast<const char*>(domain->data);
          std::size_t pattern_length = domain->length;
          if (match_pattern(pattern, pattern_length, host_.c_str()))
          {
            GENERAL_NAMES_free(gens);
            return true;
          }
        }
      }
      else if (gen->type == GEN_IPADD && is_address)
      {
        ASN1_OCTET_STRING* ip_address = gen->d.iPAddress;
        if (ip_address->type == V_ASN1_OCTET_STRING && ip_address->data)
        {
          if (address.is_v4() && ip_address->length == 4)
          {
            ip::address_v4::bytes_type bytes = address.to_v4().to_bytes();
            if (memcmp(bytes.data(), ip_address->data, 4) == 0)
            {
              GENERAL_NAMES_free(gens);
              return true;
            }
          }
          else if (address.is_v6() && ip_address->length == 16)
          {
            ip::address_v6::bytes_type bytes = address.to_v6().to_bytes();
            if (memcmp(bytes.data(), ip_address->data, 16) == 0)
            {
              GENERAL_NAMES_free(gens);
              return true;
            }
          }
        }
      }
    }
    GENERAL_NAMES_free(gens);
  
    // No match in the alternate names, so try the common names. We should only
    // use the "most specific" common name, which is the last one in the list.
    X509_NAME* name = X509_get_subject_name(cert);
    int i = -1;
    ASN1_STRING* common_name = 0;
    while ((i = X509_NAME_get_index_by_NID(name, NID_commonName, i)) >= 0)
    {
      X509_NAME_ENTRY* name_entry = X509_NAME_get_entry(name, i);
      common_name = X509_NAME_ENTRY_get_data(name_entry);
    }
    if (common_name && common_name->data && common_name->length)
    {
      const char* pattern = reinterpret_cast<const char*>(common_name->data);
      std::size_t pattern_length = common_name->length;
      if (match_pattern(pattern, pattern_length, host_.c_str()))
        return true;
    }
  
    return false;
  }
  
  bool rfc2818_verification::match_pattern(const char* pattern,
      std::size_t pattern_length, const char* host)
  {
    using namespace std; // For tolower.
  
    const char* p = pattern;
    const char* p_end = p + pattern_length;
    const char* h = host;
  
    while (p != p_end && *h)
    {
      if (*p == '*')
      {
        ++p;
        while (*h && *h != '.')
          if (match_pattern(p, p_end - p, h++))
            return true;
      }
      else if (tolower(*p) == tolower(*h))
      {
        ++p;
        ++h;
      }
      else
      {
        return false;
      }
    }
  
    return p == p_end && !*h;
  }
  
  #endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
  
  } // namespace ssl
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #endif // BOOST_ASIO_SSL_IMPL_RFC2818_VERIFICATION_IPP
  