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module Plum
class Frame
FRAME_TYPES = {
data: 0x00,
headers: 0x01,
priority: 0x02,
rst_stream: 0x03,
settings: 0x04,
push_promise: 0x05,
ping: 0x06,
goaway: 0x07,
window_update: 0x08,
continuation: 0x09
}
FRAME_FLAGS = {
data: {
end_stream: 0x01,
padded: 0x08
},
headers: {
end_stream: 0x01,
end_headers: 0x04,
padded: 0x08,
priority: 0x20
},
priority: {},
rst_stream: {},
settings: {
ack: 0x01
},
push_promise: {
end_headers: 0x04,
padded: 0x08
},
ping: {
ack: 0x01
},
goaway: {},
window_update: {},
continuation: {
end_headers: 0x04
}
}
# RFC7540: 4.1 Frame format
# +-----------------------------------------------+
# | Length (24) |
# +---------------+---------------+---------------+
# | Type (8) | Flags (8) |
# +-+-------------+---------------+-------------------------------+
# |R| Stream Identifier (31) |
# +=+=============================================================+
# | Frame Payload (0...) ...
# +---------------------------------------------------------------+
# [Integer] The length of payload. unsigned 24-bit integer
attr_reader :length
# [Integer] Frame type. 8-bit
attr_reader :type_value
# [Integer] Flags. 8-bit
attr_reader :flags_value
# [Integer] Stream Identifier. unsigned 31-bit integer
attr_reader :stream_id
# [String] The payload.
attr_reader :payload
def initialize(length: nil, type: nil, type_value: nil, flags: nil, flags_value: nil, stream_id: nil, payload: nil)
@payload = payload.to_s
@length = length || @payload.bytesize
@type_value = type_value || FRAME_TYPES[type] or raise ArgumentError.new("type_value or type is necessary")
@flags_value = flags_value || (flags && flags.map {|flag| FRAME_FLAGS[type][flag] }.inject(:|)) || 0
@stream_id = stream_id or raise ArgumentError.new("stream_id is necessary")
end
def type
FRAME_TYPES.key(type_value)
end
def flags
FRAME_FLAGS[type].select {|name, value| value & flags_value > 0 }.map {|name, value| name }
end
def assemble
bytes = ""
bytes << [length].pack("N")[1, 3] # last 3*8 bits
bytes << [type_value].pack("C")
bytes << [flags_value].pack("C")
bytes << [stream_id & ~(1 << 31)].pack("N") # first bit is reserved (MUST be 0)
bytes << payload
bytes
end
def inspect
"#<Plum::Frame:0x#{__id__.to_s(16)} length=#{length.inspect}, type=#{type.inspect}, flags=#{flags.inspect}, stream_id=0x#{stream_id.to_s(16)}, payload=#{payload.inspect}>"
end
def self.parse!(buffer)
return nil if buffer.size < 9 # header: 9 bytes
bhead = buffer[0, 9]
length = ("\x00" + bhead[0, 3]).unpack("N")[0]
return nil if buffer.size < 9 + length
payload = buffer.slice!(0...(9 + length))[9, length]
type = bhead[3, 1].unpack("C")[0]
flags = bhead[4, 1].unpack("C")[0]
r_sid = bhead[5, 4].unpack("N")[0]
r = r_sid >> 31
stream_id = r_sid & ~(1 << 31)
self.new(length: length, type_value: type, flags_value: flags, stream_id: stream_id, payload: payload)
end
end
end
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