# HTTPClient - HTTP client library.
# Copyright (C) 2000-2009  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>.
#
# This program is copyrighted free software by NAKAMURA, Hiroshi.  You can
# redistribute it and/or modify it under the same terms of Ruby's license;
# either the dual license version in 2003, or any later version.


class HTTPClient

  begin
    require 'openssl'
    SSLEnabled = true
  rescue LoadError
    SSLEnabled = false
  end

  # Represents SSL configuration for HTTPClient instance.
  # The implementation depends on OpenSSL.
  #
  # == Trust Anchor Control
  #
  # SSLConfig loads 'httpclient/cacert.p7s' as a trust anchor
  # (trusted certificate(s)) with add_trust_ca in initialization time.
  # This means that HTTPClient instance trusts some CA certificates by default,
  # like Web browsers.  'httpclient/cacert.p7s' is created by the author and
  # included in released package.
  #
  # 'cacert.p7s' is automatically generated from JDK 1.6.  Regardless its
  # filename extension (p7s), HTTPClient doesn't verify the signature in it.
  #
  # You may want to change trust anchor by yourself.  Call clear_cert_store
  # then add_trust_ca for that purpose.
  class SSLConfig
    include OpenSSL if SSLEnabled

    # String name of OpenSSL's SSL version method name: SSLv2, SSLv23 or SSLv3
    attr_reader :ssl_version
    # OpenSSL::X509::Certificate:: certificate for SSL client authenticateion.
    # nil by default. (no client authenticateion)
    attr_reader :client_cert
    # OpenSSL::PKey::PKey:: private key for SSL client authentication.
    # nil by default. (no client authenticateion)
    attr_reader :client_key

    # A number which represents OpenSSL's verify mode.  Default value is
    # OpenSSL::SSL::VERIFY_PEER | OpenSSL::SSL::VERIFY_FAIL_IF_NO_PEER_CERT.
    attr_reader :verify_mode
    # A number of verify depth.  Certification path which length is longer than
    # this depth is not allowed.
    attr_reader :verify_depth
    # A callback handler for custom certificate verification.  nil by default.
    # If the handler is set, handler.call is invoked just after general
    # OpenSSL's verification.  handler.call is invoked with 2 arguments,
    # ok and ctx; ok is a result of general OpenSSL's verification.  ctx is a
    # OpenSSL::X509::StoreContext.
    attr_reader :verify_callback
    # SSL timeout in sec.  nil by default.
    attr_reader :timeout
    # A number of OpenSSL's SSL options.  Default value is
    # OpenSSL::SSL::OP_ALL | OpenSSL::SSL::OP_NO_SSLv2
    attr_reader :options
    # A String of OpenSSL's cipher configuration.  Default value is
    # ALL:!ADH:!LOW:!EXP:!MD5:+SSLv2:@STRENGTH
    # See ciphers(1) man in OpenSSL for more detail.
    attr_reader :ciphers

    # OpenSSL::X509::X509::Store used for verification.  You can reset the
    # store with clear_cert_store and set the new store with cert_store=.
    attr_reader :cert_store # don't use if you don't know what it is.

    # For server side configuration.  Ignore this.
    attr_reader :client_ca # :nodoc:

    # Creates a SSLConfig.
    def initialize(client)
      return unless SSLEnabled
      @client = client
      @cert_store = X509::Store.new
      @client_cert = @client_key = @client_ca = nil
      @verify_mode = SSL::VERIFY_PEER | SSL::VERIFY_FAIL_IF_NO_PEER_CERT
      @verify_depth = nil
      @verify_callback = nil
      @dest = nil
      @timeout = nil
      @ssl_version = "SSLv3"
      @options = defined?(SSL::OP_ALL) ? SSL::OP_ALL | SSL::OP_NO_SSLv2 : nil
      # OpenSSL 0.9.8 default: "ALL:!ADH:!LOW:!EXP:!MD5:+SSLv2:@STRENGTH"
      @ciphers = "ALL:!aNULL:!eNULL:!SSLv2" # OpenSSL >1.0.0 default
      @cacerts_loaded = false
    end

    # Sets SSL version method String.  Possible values: "SSLv2" for SSL2,
    # "SSLv3" for SSL3 and TLS1.x, "SSLv23" for SSL3 with fallback to SSL2.
    def ssl_version=(ssl_version)
      @ssl_version = ssl_version
      change_notify
    end

    # Sets certificate (OpenSSL::X509::Certificate) for SSL client
    # authentication.
    # client_key and client_cert must be a pair.
    #
    # Calling this method resets all existing sessions.
    def client_cert=(client_cert)
      @client_cert = client_cert
      change_notify
    end

    # Sets private key (OpenSSL::PKey::PKey) for SSL client authentication.
    # client_key and client_cert must be a pair.
    #
    # Calling this method resets all existing sessions.
    def client_key=(client_key)
      @client_key = client_key
      change_notify
    end

    # Sets certificate and private key for SSL client authentication.
    # cert_file:: must be a filename of PEM/DER formatted file.
    # key_file:: must be a filename of PEM/DER formatted file.  Key must be an
    #            RSA key.  If you want to use other PKey algorithm,
    #            use client_key=.
    #
    # Calling this method resets all existing sessions.
    def set_client_cert_file(cert_file, key_file)
      @client_cert = X509::Certificate.new(File.open(cert_file) { |f| f.read })
      @client_key = PKey::RSA.new(File.open(key_file) { |f| f.read })
      change_notify
    end

    # Sets OpenSSL's default trusted CA certificates.  Generally, OpenSSL is
    # configured to use OS's trusted CA certificates located at
    # /etc/pki/certs or /etc/ssl/certs.  Unfortunately OpenSSL's Windows build
    # does not work with Windows Certificate Storage.
    #
    # On Windows or when you build OpenSSL manually, you can set the
    # CA certificates directory by SSL_CERT_DIR env variable at runtime.
    #
    #   SSL_CERT_DIR=/etc/ssl/certs ruby -rhttpclient -e "..."
    #
    # Calling this method resets all existing sessions.
    def set_default_paths
      @cacerts_loaded = true # avoid lazy override
      @cert_store = X509::Store.new
      @cert_store.set_default_paths
      change_notify
    end

    # Drops current certificate store (OpenSSL::X509::Store) for SSL and create
    # new one for the next session.
    #
    # Calling this method resets all existing sessions.
    def clear_cert_store
      @cacerts_loaded = true # avoid lazy override
      @cert_store = X509::Store.new
      change_notify
    end

    # Sets new certificate store (OpenSSL::X509::Store).
    # don't use if you don't know what it is.
    #
    # Calling this method resets all existing sessions.
    def cert_store=(cert_store)
      @cacerts_loaded = true # avoid lazy override
      @cert_store = cert_store
      change_notify
    end

    # Sets trust anchor certificate(s) for verification.
    # trust_ca_file_or_hashed_dir:: a filename of a PEM/DER formatted
    #                               OpenSSL::X509::Certificate or
    #                               a 'c-rehash'eddirectory name which stores
    #                               trusted certificate files.
    #
    # Calling this method resets all existing sessions.
    def add_trust_ca(trust_ca_file_or_hashed_dir)
      @cacerts_loaded = true # avoid lazy override
      add_trust_ca_to_store(@cert_store, trust_ca_file_or_hashed_dir)
      change_notify
    end
    alias set_trust_ca add_trust_ca

    def add_trust_ca_to_store(cert_store, trust_ca_file_or_hashed_dir)
      if FileTest.directory?(trust_ca_file_or_hashed_dir)
        cert_store.add_path(trust_ca_file_or_hashed_dir)
      else
        cert_store.add_file(trust_ca_file_or_hashed_dir)
      end
    end

    # Loads default trust anchors.
    # Calling this method resets all existing sessions.
    def load_trust_ca
      load_cacerts(@cert_store)
      change_notify
    end

    # Adds CRL for verification.
    # crl:: a OpenSSL::X509::CRL or a filename of a PEM/DER formatted
    #       OpenSSL::X509::CRL.
    #
    # Calling this method resets all existing sessions.
    def add_crl(crl)
      unless crl.is_a?(X509::CRL)
        crl = X509::CRL.new(File.open(crl) { |f| f.read })
      end
      @cert_store.add_crl(crl)
      @cert_store.flags = X509::V_FLAG_CRL_CHECK | X509::V_FLAG_CRL_CHECK_ALL
      change_notify
    end
    alias set_crl add_crl

    # Sets verify mode of OpenSSL.  New value must be a combination of
    # constants OpenSSL::SSL::VERIFY_*
    #
    # Calling this method resets all existing sessions.
    def verify_mode=(verify_mode)
      @verify_mode = verify_mode
      change_notify
    end

    # Sets verify depth.  New value must be a number.
    #
    # Calling this method resets all existing sessions.
    def verify_depth=(verify_depth)
      @verify_depth = verify_depth
      change_notify
    end

    # Sets callback handler for custom certificate verification.
    # See verify_callback.
    #
    # Calling this method resets all existing sessions.
    def verify_callback=(verify_callback)
      @verify_callback = verify_callback
      change_notify
    end

    # Sets SSL timeout in sec.
    #
    # Calling this method resets all existing sessions.
    def timeout=(timeout)
      @timeout = timeout
      change_notify
    end

    # Sets SSL options.  New value must be a combination of # constants
    # OpenSSL::SSL::OP_*
    #
    # Calling this method resets all existing sessions.
    def options=(options)
      @options = options
      change_notify
    end

    # Sets cipher configuration.  New value must be a String.
    #
    # Calling this method resets all existing sessions.
    def ciphers=(ciphers)
      @ciphers = ciphers
      change_notify
    end

    def client_ca=(client_ca) # :nodoc:
      @client_ca = client_ca
      change_notify
    end

    # interfaces for SSLSocketWrap.
    def set_context(ctx) # :nodoc:
      load_trust_ca unless @cacerts_loaded
      @cacerts_loaded = true
      # Verification: Use Store#verify_callback instead of SSLContext#verify*?
      ctx.cert_store = @cert_store
      ctx.verify_mode = @verify_mode
      ctx.verify_depth = @verify_depth if @verify_depth
      ctx.verify_callback = @verify_callback || method(:default_verify_callback)
      # SSL config
      ctx.cert = @client_cert
      ctx.key = @client_key
      ctx.client_ca = @client_ca
      ctx.timeout = @timeout
      ctx.options = @options
      ctx.ciphers = @ciphers
      ctx.ssl_version = @ssl_version
    end

    # post connection check proc for ruby < 1.8.5.
    # this definition must match with the one in ext/openssl/lib/openssl/ssl.rb
    def post_connection_check(peer_cert, hostname) # :nodoc:
      check_common_name = true
      cert = peer_cert
      cert.extensions.each{|ext|
        next if ext.oid != "subjectAltName"
        ext.value.split(/,\s+/).each{|general_name|
          if /\ADNS:(.*)/ =~ general_name
            check_common_name = false
            reg = Regexp.escape($1).gsub(/\\\*/, "[^.]+")
            return true if /\A#{reg}\z/i =~ hostname
          elsif /\AIP Address:(.*)/ =~ general_name
            check_common_name = false
            return true if $1 == hostname
          end
        }
      }
      if check_common_name
        cert.subject.to_a.each{|oid, value|
          if oid == "CN"
            reg = Regexp.escape(value).gsub(/\\\*/, "[^.]+")
            return true if /\A#{reg}\z/i =~ hostname
          end
        }
      end
      raise SSL::SSLError, "hostname was not match with the server certificate"
    end

    # Default callback for verification: only dumps error.
    def default_verify_callback(is_ok, ctx)
      if $DEBUG
        if is_ok
          warn("ok: #{ctx.current_cert.subject.to_s.dump}")
        else
          warn("ng: #{ctx.current_cert.subject.to_s.dump} at depth #{ctx.error_depth} - #{ctx.error}: #{ctx.error_string} in #{ctx.chain.inspect}")
        end
        warn(ctx.current_cert.to_text)
        warn(ctx.current_cert.to_pem)
      end
      if !is_ok
        depth = ctx.error_depth
        code = ctx.error
        msg = ctx.error_string
        warn("at depth #{depth} - #{code}: #{msg}")
      end
      is_ok
    end

    # Sample callback method:  CAUTION: does not check CRL/ARL.
    def sample_verify_callback(is_ok, ctx)
      unless is_ok
        depth = ctx.error_depth
        code = ctx.error
        msg = ctx.error_string
        warn("at depth #{depth} - #{code}: #{msg}") if $DEBUG
        return false
      end

      cert = ctx.current_cert
      self_signed = false
      ca = false
      pathlen = nil
      server_auth = true
      self_signed = (cert.subject.cmp(cert.issuer) == 0)

      # Check extensions whatever its criticality is. (sample)
      cert.extensions.each do |ex|
        case ex.oid
        when 'basicConstraints'
          /CA:(TRUE|FALSE), pathlen:(\d+)/ =~ ex.value
          ca = ($1 == 'TRUE')
          pathlen = $2.to_i
        when 'keyUsage'
          usage = ex.value.split(/\s*,\s*/)
          ca = usage.include?('Certificate Sign')
          server_auth = usage.include?('Key Encipherment')
        when 'extendedKeyUsage'
          usage = ex.value.split(/\s*,\s*/)
          server_auth = usage.include?('Netscape Server Gated Crypto')
        when 'nsCertType'
          usage = ex.value.split(/\s*,\s*/)
          ca = usage.include?('SSL CA')
          server_auth = usage.include?('SSL Server')
        end
      end

      if self_signed
        warn('self signing CA') if $DEBUG
        return true
      elsif ca
        warn('middle level CA') if $DEBUG
        return true
      elsif server_auth
        warn('for server authentication') if $DEBUG
        return true
      end

      return false
    end

  private

    def change_notify
      @client.reset_all
    end

    def load_cacerts(cert_store)
      file = File.join(File.dirname(__FILE__), 'cacert.p7s')
      add_trust_ca_to_store(cert_store, file)
    end
  end


end