implement "http" URIs support (currently only 'with prior knowledge')

1 files changed, 223 insertions, 0 deletions

diff --git a/lib/plum/connection.rb b/lib/plum/connection.rb
new file mode 100644
index 0000000..6dac8c3
--- /dev/null
+++ b/lib/plum/connection.rb
@@ -0,0 +1,223 @@
+using Plum::BinaryString
+
+module Plum
+  class Connection
+    include EventEmitter
+    include FlowControl
+    include ConnectionHelper
+
+    CLIENT_CONNECTION_PREFACE = "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
+
+    DEFAULT_SETTINGS = {
+      header_table_size:      4096,     # octets
+      enable_push:            1,        # 1: enabled, 0: disabled
+      max_concurrent_streams: 1 << 30,  # (1 << 31) / 2
+      initial_window_size:    65535,    # octets; <= 2 ** 31 - 1
+      max_frame_size:         16384,    # octets; <= 2 ** 24 - 1
+      max_header_list_size:   (1 << 32) - 1 # Fixnum
+    }
+
+    attr_reader :hpack_encoder, :hpack_decoder
+    attr_reader :local_settings, :remote_settings
+    attr_reader :state, :streams, :io
+
+    def initialize(io, local_settings = {})
+      @io = io
+      @local_settings = Hash.new {|hash, key| DEFAULT_SETTINGS[key] }.merge!(local_settings)
+      @remote_settings = Hash.new {|hash, key| DEFAULT_SETTINGS[key] }
+      @buffer = "".force_encoding(Encoding::BINARY)
+      @streams = {}
+      @state = :negotiation
+      @hpack_decoder = HPACK::Decoder.new(@local_settings[:header_table_size])
+      @hpack_encoder = HPACK::Encoder.new(@remote_settings[:header_table_size])
+      initialize_flow_control(send: @remote_settings[:initial_window_size],
+                              recv: @local_settings[:initial_window_size])
+    end
+    private :initialize
+
+    # Starts communication with the peer. It blocks until the io is closed, or reaches EOF.
+    def run
+      while !@io.closed? && !@io.eof?
+        receive @io.readpartial(1024)
+      end
+    end
+
+    # Closes the connection and closes the io. Sends GOAWAY frame to the peer.
+    #
+    # @param error_code [Integer] The error code to be contained in the GOAWAY frame.
+    def close(error_code = 0)
+      last_id = @streams.keys.reverse_each.find {|id| id.odd? }
+      data = ""
+      data.push_uint32((last_id || 0) & ~(1 << 31))
+      data.push_uint32(error_code)
+      data.push("") # debug message
+      send_immediately Frame.new(type: :goaway,
+                                 stream_id: 0,
+                                 payload: data)
+      # TODO: server MAY wait streams
+      @io.close
+    end
+
+    # Receives the specified data and process.
+    #
+    # @param new_data [String] The data received from the peer.
+    def receive(new_data)
+      return if new_data.empty?
+      @buffer << new_data
+
+      if @state == :negotiation
+        negotiate!
+      end
+
+      if @state != :negotiation
+        while frame = Frame.parse!(@buffer)
+          callback(:frame, frame)
+          receive_frame(frame)
+        end
+      end
+    rescue ConnectionError => e
+      callback(:connection_error, e)
+      close(e.http2_error_code)
+    end
+    alias << receive
+
+    # Reserves a new stream to server push.
+    #
+    # @param args [Hash] The argument to pass to Stram.new.
+    def reserve_stream(**args)
+      next_id = ((@streams.keys.last / 2).to_i + 1) * 2
+      stream = new_stream(next_id, state: :reserved_local, **args)
+      stream
+    end
+
+    private
+    def send_immediately(frame)
+      callback(:send_frame, frame)
+      @io.write(frame.assemble)
+    end
+
+    def validate_received_frame(frame)
+      case @state
+      when :waiting_settings
+        raise ConnectionError.new(:protocol_error) if frame.type != :settings
+        @state = :negotiated
+        callback(:negotiated)
+      when :waiting_continuation
+        if frame.type != :continuation || frame.stream_id != @continuation_id
+          raise Plum::ConnectionError.new(:protocol_error)
+        end
+
+        if frame.flags.include?(:end_headers)
+          @state = :open
+          @continuation_id = nil
+        end
+      else
+        if [:headers].include?(frame.type)
+          if !frame.flags.include?(:end_headers)
+            @state = :waiting_continuation
+            @continuation_id = frame.stream_id
+          end
+        end
+      end
+    end
+
+    def receive_frame(frame)
+      validate_received_frame(frame)
+
+      if frame.stream_id == 0
+        receive_control_frame(frame)
+      else
+        if @streams.key?(frame.stream_id)
+          stream = @streams[frame.stream_id]
+        else
+          if frame.stream_id.even? # stream started by client must have odd ID
+            raise Plum::ConnectionError.new(:protocol_error)
+          end
+          stream = new_stream(frame.stream_id)
+        end
+        stream.receive_frame(frame)
+      end
+    end
+
+    def receive_control_frame(frame)
+      if frame.length > @local_settings[:max_frame_size]
+        raise ConnectionError.new(:frame_size_error)
+      end
+
+      case frame.type
+      when :settings
+        receive_settings(frame)
+      when :window_update
+        receive_window_update(frame)
+      when :ping
+        receive_ping(frame)
+      when :goaway
+        close
+      when :data, :headers, :priority, :rst_stream, :push_promise, :continuation
+        raise Plum::ConnectionError.new(:protocol_error)
+      else
+        # MUST ignore unknown frame type.
+      end
+    end
+
+    def receive_settings(frame)
+      if frame.flags.include?(:ack)
+        raise ConnectionError.new(:frame_size_error) if frame.length != 0
+        return
+      end
+
+      raise ConnectionError.new(:frame_size_error) if frame.length % 6 != 0
+
+      old_remote_settings = @remote_settings.dup
+      @remote_settings.merge!(frame.parse_settings)
+      apply_remote_settings(old_remote_settings)
+
+      callback(:remote_settings, @remote_settings, old_remote_settings)
+
+      send_immediately Frame.new(type: :settings, stream_id: 0x00, flags: [:ack])
+    end
+
+    def update_local_settings(new_settings)
+      old_settings = @local_settings.dup
+      @local_settings.merge!(new_settings)
+
+      @hpack_decoder.limit = @local_settings[:header_table_size]
+      update_recv_initial_window_size(@local_settings[:initial_window_size] - old_settings[:initial_window_size])
+    end
+
+    def apply_remote_settings(old_remote_settings)
+      @hpack_encoder.limit = @remote_settings[:header_table_size]
+      update_send_initial_window_size(@remote_settings[:initial_window_size] - old_remote_settings[:initial_window_size])
+    end
+
+    def receive_ping(frame)
+      raise Plum::ConnectionError.new(:frame_size_error) if frame.length != 8
+
+      if frame.flags.include?(:ack)
+        on(:ping_ack)
+      else
+        on(:ping)
+        opaque_data = frame.payload
+        send_immediately Frame.new(type: :ping,
+                                   stream_id: 0,
+                                   flags: [:ack],
+                                   payload: opaque_data)
+      end
+    end
+
+    def new_stream(stream_id, **args)
+      if @streams.size > 0 && @streams.keys.last >= stream_id
+        raise Plum::ConnectionError.new(:protocol_error)
+      end
+
+      stream = Stream.new(self, stream_id, **args)
+      callback(:stream, stream)
+      @streams[stream_id] = stream
+      stream
+    end
+
+    def local_error
+      ConnectionError
+    end
+  end
+end