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module Plum
class ServerConnection
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
def initialize(socket, local_settings = {})
@socket = socket
@local_settings = DEFAULT_SETTINGS.merge(local_settings)
@callbacks = Hash.new {|hash, key| hash[key] = [] }
@buffer = BinaryString.new
@streams = {}
@state = :waiting_for_connetion_preface
@last_stream_id = 0
@hpack_decoder = HPACK::Decoder.new(@local_settings[:header_table_size])
@hpack_encoder = HPACK::Encoder.new(DEFAULT_SETTINGS[:header_table_size])
end
def send(frame)
callback(:send_frame, frame)
@socket.write(frame.assemble)
end
def start
update_settings(@local_settings)
process(@socket.readpartial(1024)) until @socket.eof?
rescue Plum::ConnectionError => e
callback(:connection_error, e)
data = BinaryString.new
data.push_uint32(@last_stream_id & ~(1 << 31))
data.push_uint32(e.http2_error_code)
data.push("") # debug message
error = Frame.new(type: :goaway,
stream_id: 0,
payload: data)
send(error)
# TODO: server MAY wait streams
@socket.close
end
def update_settings(**kwargs)
payload = kwargs.inject(BinaryString.new) {|payload, (key, value)|
payload.push_uint16(Frame::SETTINGS_TYPE[key])
payload.push_uint32(value)
}
frame = Frame.new(type: :settings,
stream_id: 0,
payload: payload)
send(frame)
end
def on(name, &blk)
@callbacks[name] << blk
end
def promise_stream
next_id = ((@streams.keys.last / 2).to_i + 1) * 2
stream = Stream.new(self, next_id, state: :reserved)
@streams[next_id] = stream
stream
end
private
def callback(name, *args)
@callbacks[name].each {|cb| cb.call(*args) }
end
def process(new_data)
@buffer << new_data
if @state == :waiting_for_connetion_preface
return if @buffer.size < 24
if @buffer.shift(24) != CLIENT_CONNECTION_PREFACE
raise Plum::ConnectionError.new(:protocol_error) # (MAY) send GOAWAY. sending.
end
@state = :waiting_for_settings
end
while frame = Frame.parse!(@buffer)
callback(:frame, frame)
if @state == :waiting_for_settings && frame.type != :settings
raise Plum::ConnectionError.new(:protocol_error)
end
if frame.stream_id == 0
process_control_frame(frame)
else
stream = @streams[frame.stream_id]
if stream
stream.on_frame(frame)
else
new_stream(frame)
end
@last_stream_id = [frame.stream_id, @last_stream_id].max
end
end
end
def process_control_frame(frame)
case frame.type
when :settings
process_settings(frame)
callback(:settings, @remote_settings)
@state = :initialized if @state == :waiting_for_settings
when :window_update
when :ping
on(:ping)
opaque_data = frame.payload
send Frame.new(type: :ping,
stream_id: 0,
flags: [:ack],
payload: opaque_data)
when :goaway
when :data, :headers, :priority, :rst_stream, :push_promise, :continuation
raise Plum::ConnectionError.new(:protocol_error)
else
raie Error.new("unknown frame type: #{frame.inspect}")
end
end
def process_settings(frame)
payload = frame.payload.dup
received = (frame.length / (2 + 4)).times.map {
id = payload.uint16!
val = payload.uint32!
[Frame::SETTINGS_TYPE.key(id), val]
}
@remote_settings = DEFAULT_SETTINGS.merge(received.to_h)
@hpack_encoder.limit = @remote_settings[:header_table_size]
settings_ack = Frame.new(type: :settings, stream_id: 0x00, flags: [:ack])
send(settings_ack)
end
def new_stream(frame)
if (frame.stream_id % 2 == 0) ||
(@streams.size > 0 && @streams.keys.last >= frame.stream_id)
raise Plum::ConnectionError.new(:protocol_error)
end
unless frame.type == :headers
raise Plum::ConnectionError.new(:protocol_error)
end
@streams.select {|id, s| s.state == :idle }.each {|id, s| s.close }
stream = Stream.new(self, frame.stream_id)
@streams[frame.stream_id] = stream
callback(:stream, stream)
stream.on_frame(frame)
end
end
end
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