Mini Shell

# frozen_string_literal: false
=begin
= Info
  'OpenSSL for Ruby 2' project
  Copyright (C) 2001 GOTOU YUUZOU <gotoyuzo@notwork.org>
  All rights reserved.

= Licence
  This program is licensed under the same licence as Ruby.
  (See the file 'LICENCE'.)
=end

require "openssl/buffering"
require "io/nonblock"

module OpenSSL
  module SSL
    class SSLContext
      DEFAULT_PARAMS = { # :nodoc:
        :ssl_version => "SSLv23",
        :verify_mode => OpenSSL::SSL::VERIFY_PEER,
        :verify_hostname => true,
        :options => -> {
          opts = OpenSSL::SSL::OP_ALL
          opts &= ~OpenSSL::SSL::OP_DONT_INSERT_EMPTY_FRAGMENTS
          opts |= OpenSSL::SSL::OP_NO_COMPRESSION if defined?(OpenSSL::SSL::OP_NO_COMPRESSION)
          opts |= OpenSSL::SSL::OP_NO_SSLv2 | OpenSSL::SSL::OP_NO_SSLv3
          opts
        }.call
      }

      if !(OpenSSL::OPENSSL_VERSION.start_with?("OpenSSL") &&
           OpenSSL::OPENSSL_VERSION_NUMBER >= 0x10100000)
        DEFAULT_PARAMS.merge!(
          ciphers: %w{
            ECDHE-ECDSA-AES128-GCM-SHA256
            ECDHE-RSA-AES128-GCM-SHA256
            ECDHE-ECDSA-AES256-GCM-SHA384
            ECDHE-RSA-AES256-GCM-SHA384
            DHE-RSA-AES128-GCM-SHA256
            DHE-DSS-AES128-GCM-SHA256
            DHE-RSA-AES256-GCM-SHA384
            DHE-DSS-AES256-GCM-SHA384
            ECDHE-ECDSA-AES128-SHA256
            ECDHE-RSA-AES128-SHA256
            ECDHE-ECDSA-AES128-SHA
            ECDHE-RSA-AES128-SHA
            ECDHE-ECDSA-AES256-SHA384
            ECDHE-RSA-AES256-SHA384
            ECDHE-ECDSA-AES256-SHA
            ECDHE-RSA-AES256-SHA
            DHE-RSA-AES128-SHA256
            DHE-RSA-AES256-SHA256
            DHE-RSA-AES128-SHA
            DHE-RSA-AES256-SHA
            DHE-DSS-AES128-SHA256
            DHE-DSS-AES256-SHA256
            DHE-DSS-AES128-SHA
            DHE-DSS-AES256-SHA
            AES128-GCM-SHA256
            AES256-GCM-SHA384
            AES128-SHA256
            AES256-SHA256
            AES128-SHA
            AES256-SHA
          }.join(":"),
        )
      end

      DEFAULT_CERT_STORE = OpenSSL::X509::Store.new # :nodoc:
      DEFAULT_CERT_STORE.set_default_paths
      DEFAULT_CERT_STORE.flags = OpenSSL::X509::V_FLAG_CRL_CHECK_ALL

      # A callback invoked when DH parameters are required.
      #
      # The callback is invoked with the Session for the key exchange, an
      # flag indicating the use of an export cipher and the keylength
      # required.
      #
      # The callback must return an OpenSSL::PKey::DH instance of the correct
      # key length.

      attr_accessor :tmp_dh_callback

      # A callback invoked at connect time to distinguish between multiple
      # server names.
      #
      # The callback is invoked with an SSLSocket and a server name.  The
      # callback must return an SSLContext for the server name or nil.
      attr_accessor :servername_cb if ExtConfig::HAVE_TLSEXT_HOST_NAME

      # call-seq:
      #    SSLContext.new => ctx
      #    SSLContext.new(:TLSv1) => ctx
      #    SSLContext.new("SSLv23_client") => ctx
      #
      # You can get a list of valid methods with OpenSSL::SSL::SSLContext::METHODS
      def initialize(version = nil)
        self.options |= OpenSSL::SSL::OP_ALL
        self.ssl_version = version if version
      end

      ##
      # call-seq:
      #   ctx.set_params(params = {}) -> params
      #
      # Sets saner defaults optimized for the use with HTTP-like protocols.
      #
      # If a Hash +params+ is given, the parameters are overridden with it.
      # The keys in +params+ must be assignment methods on SSLContext.
      #
      # If the verify_mode is not VERIFY_NONE and ca_file, ca_path and
      # cert_store are not set then the system default certificate store is
      # used.
      def set_params(params={})
        params = DEFAULT_PARAMS.merge(params)
        params.each{|name, value| self.__send__("#{name}=", value) }
        if self.verify_mode != OpenSSL::SSL::VERIFY_NONE
          unless self.ca_file or self.ca_path or self.cert_store
            self.cert_store = DEFAULT_CERT_STORE
          end
        end
        return params
      end
    end

    module SocketForwarder
      def addr
        to_io.addr
      end

      def peeraddr
        to_io.peeraddr
      end

      def setsockopt(level, optname, optval)
        to_io.setsockopt(level, optname, optval)
      end

      def getsockopt(level, optname)
        to_io.getsockopt(level, optname)
      end

      def fcntl(*args)
        to_io.fcntl(*args)
      end

      def closed?
        to_io.closed?
      end

      def do_not_reverse_lookup=(flag)
        to_io.do_not_reverse_lookup = flag
      end
    end

    def verify_certificate_identity(cert, hostname)
      should_verify_common_name = true
      cert.extensions.each{|ext|
        next if ext.oid != "subjectAltName"
        ostr = OpenSSL::ASN1.decode(ext.to_der).value.last
        sequence = OpenSSL::ASN1.decode(ostr.value)
        sequence.value.each{|san|
          case san.tag
          when 2 # dNSName in GeneralName (RFC5280)
            should_verify_common_name = false
            return true if verify_hostname(hostname, san.value)
          when 7 # iPAddress in GeneralName (RFC5280)
            should_verify_common_name = false
            # follows GENERAL_NAME_print() in x509v3/v3_alt.c
            if san.value.size == 4
              return true if san.value.unpack('C*').join('.') == hostname
            elsif san.value.size == 16
              return true if san.value.unpack('n*').map { |e| sprintf("%X", e) }.join(':') == hostname
            end
          end
        }
      }
      if should_verify_common_name
        cert.subject.to_a.each{|oid, value|
          if oid == "CN"
            return true if verify_hostname(hostname, value)
          end
        }
      end
      return false
    end
    module_function :verify_certificate_identity

    def verify_hostname(hostname, san) # :nodoc:
      # RFC 5280, IA5String is limited to the set of ASCII characters
      return false unless san.ascii_only?
      return false unless hostname.ascii_only?

      # See RFC 6125, section 6.4.1
      # Matching is case-insensitive.
      san_parts = san.downcase.split(".")

      # TODO: this behavior should probably be more strict
      return san == hostname if san_parts.size < 2

      # Matching is case-insensitive.
      host_parts = hostname.downcase.split(".")

      # RFC 6125, section 6.4.3, subitem 2.
      # If the wildcard character is the only character of the left-most
      # label in the presented identifier, the client SHOULD NOT compare
      # against anything but the left-most label of the reference
      # identifier (e.g., *.example.com would match foo.example.com but
      # not bar.foo.example.com or example.com).
      return false unless san_parts.size == host_parts.size

      # RFC 6125, section 6.4.3, subitem 1.
      # The client SHOULD NOT attempt to match a presented identifier in
      # which the wildcard character comprises a label other than the
      # left-most label (e.g., do not match bar.*.example.net).
      return false unless verify_wildcard(host_parts.shift, san_parts.shift)

      san_parts.join(".") == host_parts.join(".")
    end
    module_function :verify_hostname

    def verify_wildcard(domain_component, san_component) # :nodoc:
      parts = san_component.split("*", -1)

      return false if parts.size > 2
      return san_component == domain_component if parts.size == 1

      # RFC 6125, section 6.4.3, subitem 3.
      # The client SHOULD NOT attempt to match a presented identifier
      # where the wildcard character is embedded within an A-label or
      # U-label of an internationalized domain name.
      return false if domain_component.start_with?("xn--") && san_component != "*"

      parts[0].length + parts[1].length < domain_component.length &&
      domain_component.start_with?(parts[0]) &&
      domain_component.end_with?(parts[1])
    end
    module_function :verify_wildcard

    class SSLSocket
      include Buffering
      include SocketForwarder

      if ExtConfig::HAVE_TLSEXT_HOST_NAME
        attr_reader :hostname
      end

      # The underlying IO object.
      attr_reader :io
      alias :to_io :io

      # The SSLContext object used in this connection.
      attr_reader :context

      # Whether to close the underlying socket as well, when the SSL/TLS
      # connection is shut down. This defaults to +false+.
      attr_accessor :sync_close

      # call-seq:
      #    ssl.sysclose => nil
      #
      # Sends "close notify" to the peer and tries to shut down the SSL
      # connection gracefully.
      #
      # If sync_close is set to +true+, the underlying IO is also closed.
      def sysclose
        return if closed?
        stop
        io.close if sync_close
      end

      # call-seq:
      #   ssl.post_connection_check(hostname) -> true
      #
      # Perform hostname verification following RFC 6125.
      #
      # This method MUST be called after calling #connect to ensure that the
      # hostname of a remote peer has been verified.
      def post_connection_check(hostname)
        if peer_cert.nil?
          msg = "Peer verification enabled, but no certificate received."
          if using_anon_cipher?
            msg += " Anonymous cipher suite #{cipher[0]} was negotiated. " \
                   "Anonymous suites must be disabled to use peer verification."
          end
          raise SSLError, msg
        end

        unless OpenSSL::SSL.verify_certificate_identity(peer_cert, hostname)
          raise SSLError, "hostname \"#{hostname}\" does not match the server certificate"
        end
        return true
      end

      # call-seq:
      #   ssl.session -> aSession
      #
      # Returns the SSLSession object currently used, or nil if the session is
      # not established.
      def session
        SSL::Session.new(self)
      rescue SSL::Session::SessionError
        nil
      end

      private

      def using_anon_cipher?
        ctx = OpenSSL::SSL::SSLContext.new
        ctx.ciphers = "aNULL"
        ctx.ciphers.include?(cipher)
      end

      def client_cert_cb
        @context.client_cert_cb
      end

      def tmp_dh_callback
        @context.tmp_dh_callback || OpenSSL::PKey::DEFAULT_TMP_DH_CALLBACK
      end

      def tmp_ecdh_callback
        @context.tmp_ecdh_callback
      end

      def session_new_cb
        @context.session_new_cb
      end

      def session_get_cb
        @context.session_get_cb
      end
    end

    ##
    # SSLServer represents a TCP/IP server socket with Secure Sockets Layer.
    class SSLServer
      include SocketForwarder
      # When true then #accept works exactly the same as TCPServer#accept
      attr_accessor :start_immediately

      # Creates a new instance of SSLServer.
      # * +srv+ is an instance of TCPServer.
      # * +ctx+ is an instance of OpenSSL::SSL::SSLContext.
      def initialize(svr, ctx)
        @svr = svr
        @ctx = ctx
        unless ctx.session_id_context
          # see #6137 - session id may not exceed 32 bytes
          prng = ::Random.new($0.hash)
          session_id = prng.bytes(16).unpack('H*')[0]
          @ctx.session_id_context = session_id
        end
        @start_immediately = true
      end

      # Returns the TCPServer passed to the SSLServer when initialized.
      def to_io
        @svr
      end

      # See TCPServer#listen for details.
      def listen(backlog=5)
        @svr.listen(backlog)
      end

      # See BasicSocket#shutdown for details.
      def shutdown(how=Socket::SHUT_RDWR)
        @svr.shutdown(how)
      end

      # Works similar to TCPServer#accept.
      def accept
        # Socket#accept returns [socket, addrinfo].
        # TCPServer#accept returns a socket.
        # The following comma strips addrinfo.
        sock, = @svr.accept
        begin
          ssl = OpenSSL::SSL::SSLSocket.new(sock, @ctx)
          ssl.sync_close = true
          ssl.accept if @start_immediately
          ssl
        rescue Exception => ex
          if ssl
            ssl.close
          else
            sock.close
          end
          raise ex
        end
      end

      # See IO#close for details.
      def close
        @svr.close
      end
    end
  end
end