Class: HTTP2::Framer
Overview
Performs encoding, decoding, and validation of binary HTTP/2 frames.
Constant Summary collapse
- DEFAULT_MAX_FRAME_SIZE =
Default value of max frame size (16384 bytes)
2**14
- MAX_STREAM_ID =
Maximum stream ID (2^31)
0x7fffffff
- MAX_WINDOWINC =
Maximum window increment value (2^31)
0x7fffffff
- FRAME_TYPES =
HTTP/2 frame type mapping as defined by the spec
{ data: 0x0, headers: 0x1, priority: 0x2, rst_stream: 0x3, settings: 0x4, push_promise: 0x5, ping: 0x6, goaway: 0x7, window_update: 0x8, continuation: 0x9, altsvc: 0xa, }
- FRAME_TYPES_WITH_PADDING =
[ :data, :headers, :push_promise ]
- FRAME_FLAGS =
Per frame flags as defined by the spec
{ data: { end_stream: 0, padded: 3, compressed: 5 }, headers: { end_stream: 0, end_headers: 2, padded: 3, priority: 5, }, priority: {}, rst_stream: {}, settings: { ack: 0 }, push_promise: { end_headers: 2, padded: 3, }, ping: { ack: 0 }, goaway: {}, window_update:{}, continuation: { end_headers: 2 }, altsvc: {}, }
- DEFINED_SETTINGS =
Default settings as defined by the spec
{ settings_header_table_size: 1, settings_enable_push: 2, settings_max_concurrent_streams: 3, settings_initial_window_size: 4, settings_max_frame_size: 5, settings_max_header_list_size: 6, }
- DEFINED_ERRORS =
Default error types as defined by the spec
{ no_error: 0, protocol_error: 1, internal_error: 2, flow_control_error: 3, settings_timeout: 4, stream_closed: 5, frame_size_error: 6, refused_stream: 7, cancel: 8, compression_error: 9, connect_error: 10, enhance_your_calm: 11, inadequate_security: 12, }
- FRAME_LENGTH_HISHIFT =
16
- FRAME_LENGTH_LOMASK =
0xFFFF
Instance Attribute Summary collapse
-
#max_frame_size ⇒ Object
Current maximum frame size.
Instance Method Summary collapse
-
#commonHeader(frame) ⇒ String
Generates common 9-byte frame header.
-
#generate(frame) ⇒ Object
Generates encoded HTTP/2 frame.
-
#initialize ⇒ Framer
constructor
Initializes new framer object.
-
#parse(buf) ⇒ Object
Decodes complete HTTP/2 frame from provided buffer.
-
#readCommonHeader(buf) ⇒ Object
Decodes common 9-byte header.
Constructor Details
#initialize ⇒ Framer
Initializes new framer object.
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# File 'lib/http/2/framer.rb', line 103 def initialize @max_frame_size = DEFAULT_MAX_FRAME_SIZE end |
Instance Attribute Details
#max_frame_size ⇒ Object
Current maximum frame size
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# File 'lib/http/2/framer.rb', line 12 def max_frame_size @max_frame_size end |
Instance Method Details
#commonHeader(frame) ⇒ String
Generates common 9-byte frame header.
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# File 'lib/http/2/framer.rb', line 112 def commonHeader(frame) header = [] if !FRAME_TYPES[frame[:type]] raise CompressionError.new("Invalid frame type (#{frame[:type]})") end if frame[:length] > @max_frame_size raise CompressionError.new("Frame size is too large: #{frame[:length]}") end if frame[:length] < 0 raise CompressionError.new("Frame size is invalid: #{frame[:length]}") end if frame[:stream] > MAX_STREAM_ID raise CompressionError.new("Stream ID (#{frame[:stream]}) is too large") end if frame[:type] == :window_update && frame[:increment] > MAX_WINDOWINC raise CompressionError.new("Window increment (#{frame[:increment]}) is too large") end header << (frame[:length] >> FRAME_LENGTH_HISHIFT) header << (frame[:length] & FRAME_LENGTH_LOMASK) header << FRAME_TYPES[frame[:type]] header << frame[:flags].reduce(0) do |acc, f| position = FRAME_FLAGS[frame[:type]][f] if !position raise CompressionError.new("Invalid frame flag (#{f}) for #{frame[:type]}") end acc |= (1 << position) acc end header << frame[:stream] header.pack(HEADERPACK) # 8+16,8,8,32 end |
#generate(frame) ⇒ Object
Generates encoded HTTP/2 frame.
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# File 'lib/http/2/framer.rb', line 176 def generate(frame) bytes = Buffer.new length = 0 frame[:flags] ||= [] frame[:stream] ||= 0 case frame[:type] when :data bytes << frame[:payload] length += frame[:payload].bytesize when :headers if frame[:weight] || frame[:stream_dependency] || !frame[:exclusive].nil? unless frame[:weight] && frame[:stream_dependency] && !frame[:exclusive].nil? raise CompressionError.new("Must specify all of priority parameters for #{frame[:type]}") end frame[:flags] += [:priority] if !frame[:flags].include? :priority end if frame[:flags].include? :priority bytes << [(frame[:exclusive] ? EBIT : 0) | (frame[:stream_dependency] & RBIT)].pack(UINT32) bytes << [frame[:weight] - 1].pack(UINT8) length += 5 end bytes << frame[:payload] length += frame[:payload].bytesize when :priority unless frame[:weight] && frame[:stream_dependency] && !frame[:exclusive].nil? raise CompressionError.new("Must specify all of priority parameters for #{frame[:type]}") end bytes << [(frame[:exclusive] ? EBIT : 0) | (frame[:stream_dependency] & RBIT)].pack(UINT32) bytes << [frame[:weight] - 1].pack(UINT8) length += 5 when :rst_stream bytes << pack_error(frame[:error]) length += 4 when :settings if frame[:stream] != 0 raise CompressionError.new("Invalid stream ID (#{frame[:stream]})") end frame[:payload].each do |(k,v)| if k.is_a? Integer DEFINED_SETTINGS.has_value?(k) or next else k = DEFINED_SETTINGS[k] if k.nil? raise CompressionError.new("Unknown settings ID for #{k}") end end bytes << [k].pack(UINT16) bytes << [v].pack(UINT32) length += 6 end when :push_promise bytes << [frame[:promise_stream] & RBIT].pack(UINT32) bytes << frame[:payload] length += 4 + frame[:payload].bytesize when :ping if frame[:payload].bytesize != 8 raise CompressionError.new("Invalid payload size \ (#{frame[:payload].size} != 8 bytes)") end bytes << frame[:payload] length += 8 when :goaway bytes << [frame[:last_stream] & RBIT].pack(UINT32) bytes << pack_error(frame[:error]) length += 8 if frame[:payload] bytes << frame[:payload] length += frame[:payload].bytesize end when :window_update bytes << [frame[:increment] & RBIT].pack(UINT32) length += 4 when :continuation bytes << frame[:payload] length += frame[:payload].bytesize when :altsvc bytes << [frame[:max_age], frame[:port]].pack(UINT32 + UINT16) length += 6 if frame[:proto] frame[:proto].bytesize > 255 and raise CompressionError.new("Proto too long") bytes << [frame[:proto].bytesize].pack(UINT8) << frame[:proto].force_encoding(BINARY) length += 1 + frame[:proto].bytesize else bytes << [0].pack(UINT8) length += 1 end if frame[:host] frame[:host].bytesize > 255 and raise CompressionError.new("Host too long") bytes << [frame[:host].bytesize].pack(UINT8) << frame[:host].force_encoding(BINARY) length += 1 + frame[:host].bytesize else bytes << [0].pack(UINT8) length += 1 end if frame[:origin] bytes << frame[:origin] length += frame[:origin].bytesize end end # Process padding. # frame[:padding] gives number of extra octets to be added. # - http://tools.ietf.org/html/draft-ietf-httpbis-http2-12#section-6.1 if frame[:padding] unless FRAME_TYPES_WITH_PADDING.include?(frame[:type]) raise CompressionError.new("Invalid padding flag for #{frame[:type]}") end padlen = frame[:padding] if padlen <= 0 || padlen > 256 || padlen + length > @max_frame_size raise CompressionError.new("Invalid padding #{padlen}") end length += padlen bytes.prepend([padlen -= 1].pack(UINT8)) frame[:flags] << :padded # Padding: Padding octets that contain no application semantic value. # Padding octets MUST be set to zero when sending and ignored when # receiving. bytes << "\0" * padlen end frame[:length] = length bytes.prepend(commonHeader(frame)) end |
#parse(buf) ⇒ Object
Decodes complete HTTP/2 frame from provided buffer. If the buffer does not contain enough data, no further work is performed.
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# File 'lib/http/2/framer.rb', line 328 def parse(buf) return nil if buf.size < 9 frame = readCommonHeader(buf) return nil if buf.size < 9 + frame[:length] buf.read(9) payload = buf.read(frame[:length]) # Implementations MUST discard frames # that have unknown or unsupported types. # - http://tools.ietf.org/html/draft-ietf-httpbis-http2-14#section-5.5 return nil if frame[:type].nil? # Process padding padlen = 0 if FRAME_TYPES_WITH_PADDING.include?(frame[:type]) padded = frame[:flags].include?(:padded) if padded padlen = payload.read(1).unpack(UINT8).first frame[:padding] = padlen + 1 padlen > payload.bytesize and raise ProtocolError.new("padding too long") padlen > 0 and payload.slice!(-padlen,padlen) frame[:length] -= frame[:padding] frame[:flags].delete(:padded) end end case frame[:type] when :data frame[:payload] = payload.read(frame[:length]) when :headers if frame[:flags].include? :priority e_sd = payload.read_uint32 frame[:stream_dependency] = e_sd & RBIT frame[:exclusive] = (e_sd & EBIT) != 0 frame[:weight] = payload.getbyte + 1 end frame[:payload] = payload.read(frame[:length]) when :priority e_sd = payload.read_uint32 frame[:stream_dependency] = e_sd & RBIT frame[:exclusive] = (e_sd & EBIT) != 0 frame[:weight] = payload.getbyte + 1 when :rst_stream frame[:error] = unpack_error payload.read_uint32 when :settings # NOTE: frame[:length] might not match the number of frame[:payload] # because unknown extensions are ignored. frame[:payload] = [] unless frame[:length] % 6 == 0 raise ProtocolError.new("Invalid settings payload length") end if frame[:stream] != 0 raise ProtocolError.new("Invalid stream ID (#{frame[:stream]})") end (frame[:length] / 6).times do id = payload.read(2).unpack(UINT16).first val = payload.read_uint32 # Unsupported or unrecognized settings MUST be ignored. # Here we send it along. name, _ = DEFINED_SETTINGS.select { |name, v| v == id }.first frame[:payload] << [name, val] if name end when :push_promise frame[:promise_stream] = payload.read_uint32 & RBIT frame[:payload] = payload.read(frame[:length]) when :ping frame[:payload] = payload.read(frame[:length]) when :goaway frame[:last_stream] = payload.read_uint32 & RBIT frame[:error] = unpack_error payload.read_uint32 size = frame[:length] - 8 # for last_stream and error frame[:payload] = payload.read(size) if size > 0 when :window_update frame[:increment] = payload.read_uint32 & RBIT when :continuation frame[:payload] = payload.read(frame[:length]) when :altsvc frame[:max_age], frame[:port] = payload.read(6).unpack(UINT32 + UINT16) len = payload.getbyte len > 0 and frame[:proto] = payload.read(len) len = payload.getbyte len > 0 and frame[:host] = payload.read(len) if payload.size > 0 frame[:origin] = payload.read(payload.size) end else # Unknown frame type is explicitly allowed end frame end |
#readCommonHeader(buf) ⇒ Object
Decodes common 9-byte header.
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# File 'lib/http/2/framer.rb', line 155 def readCommonHeader(buf) frame = {} len_hi, len_lo, type, flags, stream = buf.slice(0,9).unpack(HEADERPACK) frame[:length] = (len_hi << FRAME_LENGTH_HISHIFT) | len_lo frame[:type], _ = FRAME_TYPES.select { |t,pos| type == pos }.first if frame[:type] frame[:flags] = FRAME_FLAGS[frame[:type]].reduce([]) do |acc, (name, pos)| acc << name if (flags & (1 << pos)) > 0 acc end end frame[:stream] = stream & RBIT frame end |