make examples work

1 files changed, 114 insertions, 0 deletions

diff --git a/lib/plum/frame.rb b/lib/plum/frame.rb
new file mode 100644
index 0000000..cbddbe8
--- /dev/null
+++ b/lib/plum/frame.rb
@@ -0,0 +1,114 @@
+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