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|
import base64
import hashlib
import os
import struct
import io
from .. import utils, odict, tcp
class Frame(object):
"""
Baseclass Frame
contains header
payload is defined in subclasses
"""
FLAG_NO_FLAGS = 0x0
FLAG_ACK = 0x1
FLAG_END_STREAM = 0x1
FLAG_END_HEADERS = 0x4
FLAG_PADDED = 0x8
FLAG_PRIORITY = 0x20
def __init__(self, length, flags, stream_id):
valid_flags = reduce(lambda x, y: x | y, self.VALID_FLAGS, 0x0)
if flags | valid_flags != valid_flags:
raise ValueError('invalid flags detected.')
self.length = length
self.flags = flags
self.stream_id = stream_id
@classmethod
def from_bytes(self, data):
fields = struct.unpack("!HBBBL", data[:9])
length = (fields[0] << 8) + fields[1]
# type is already deducted from class
flags = fields[3]
stream_id = fields[4]
return FRAMES[fields[2]].from_bytes(length, flags, stream_id, data[9:])
def to_bytes(self):
payload = self.payload_bytes()
self.length = len(payload)
b = struct.pack('!HB', self.length & 0xFFFF00, self.length & 0x0000FF)
b += struct.pack('!B', self.TYPE)
b += struct.pack('!B', self.flags)
b += struct.pack('!L', self.stream_id & 0x7FFFFFFF)
b += payload
return b
def __eq__(self, other):
return self.to_bytes() == other.to_bytes()
class DataFrame(Frame):
TYPE = 0x0
VALID_FLAGS = [Frame.FLAG_END_STREAM, Frame.FLAG_PADDED]
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, payload=b'', pad_length=0):
super(DataFrame, self).__init__(length, flags, stream_id)
self.payload = payload
self.pad_length = pad_length
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
if f.flags & self.FLAG_PADDED:
f.pad_length = struct.unpack('!B', payload[0])[0]
f.payload = payload[1:-f.pad_length]
else:
f.payload = payload
return f
def payload_bytes(self):
if self.stream_id == 0x0:
raise ValueError('DATA frames MUST be associated with a stream.')
b = b''
if self.flags & self.FLAG_PADDED:
b += struct.pack('!B', self.pad_length)
b += bytes(self.payload)
if self.flags & self.FLAG_PADDED:
b += b'\0' * self.pad_length
return b
class HeadersFrame(Frame):
TYPE = 0x1
VALID_FLAGS = [Frame.FLAG_END_STREAM, Frame.FLAG_END_HEADERS, Frame.FLAG_PADDED, Frame.FLAG_PRIORITY]
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, header_block_fragment=b'', pad_length=0, exclusive=False, stream_dependency=0x0, weight=0):
super(HeadersFrame, self).__init__(length, flags, stream_id)
self.header_block_fragment = header_block_fragment
self.pad_length = pad_length
self.exclusive = exclusive
self.stream_dependency = stream_dependency
self.weight = weight
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
if f.flags & self.FLAG_PADDED:
f.pad_length = struct.unpack('!B', payload[0])[0]
f.header_block_fragment = payload[1:-f.pad_length]
else:
f.header_block_fragment = payload[0:]
if f.flags & self.FLAG_PRIORITY:
f.stream_dependency, f.weight = struct.unpack('!LB', f.header_block_fragment[:5])
f.exclusive = bool(f.stream_dependency >> 31)
f.stream_dependency &= 0x7FFFFFFF
f.header_block_fragment = f.header_block_fragment[5:]
return f
def payload_bytes(self):
if self.stream_id == 0x0:
raise ValueError('HEADERS frames MUST be associated with a stream.')
b = b''
if self.flags & self.FLAG_PADDED:
b += struct.pack('!B', self.pad_length)
if self.flags & self.FLAG_PRIORITY:
b += struct.pack('!LB', (int(self.exclusive) << 31) | self.stream_dependency, self.weight)
b += bytes(self.header_block_fragment)
if self.flags & self.FLAG_PADDED:
b += b'\0' * self.pad_length
return b
class PriorityFrame(Frame):
TYPE = 0x2
VALID_FLAGS = []
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, exclusive=False, stream_dependency=0x0, weight=0):
super(PriorityFrame, self).__init__(length, flags, stream_id)
self.exclusive = exclusive
self.stream_dependency = stream_dependency
self.weight = weight
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
f.stream_dependency, f.weight = struct.unpack('!LB', payload)
f.exclusive = bool(f.stream_dependency >> 31)
f.stream_dependency &= 0x7FFFFFFF
return f
def payload_bytes(self):
if self.stream_id == 0x0:
raise ValueError('PRIORITY frames MUST be associated with a stream.')
if self.stream_dependency == 0x0:
raise ValueError('stream dependency is invalid.')
return struct.pack('!LB', (int(self.exclusive) << 31) | self.stream_dependency, self.weight)
class RstStreamFrame(Frame):
TYPE = 0x3
VALID_FLAGS = []
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, error_code=0x0):
super(RstStreamFrame, self).__init__(length, flags, stream_id)
self.error_code = error_code
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
f.error_code = struct.unpack('!L', payload)[0]
return f
def payload_bytes(self):
if self.stream_id == 0x0:
raise ValueError('RST_STREAM frames MUST be associated with a stream.')
return struct.pack('!L', self.error_code)
class SettingsFrame(Frame):
TYPE = 0x4
VALID_FLAGS = [Frame.FLAG_ACK]
SETTINGS = utils.BiDi(
SETTINGS_HEADER_TABLE_SIZE = 0x1,
SETTINGS_ENABLE_PUSH = 0x2,
SETTINGS_MAX_CONCURRENT_STREAMS = 0x3,
SETTINGS_INITIAL_WINDOW_SIZE = 0x4,
SETTINGS_MAX_FRAME_SIZE = 0x5,
SETTINGS_MAX_HEADER_LIST_SIZE = 0x6,
)
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, settings={}):
super(SettingsFrame, self).__init__(length, flags, stream_id)
self.settings = settings
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
for i in xrange(0, len(payload), 6):
identifier, value = struct.unpack("!HL", payload[i:i+6])
f.settings[identifier] = value
return f
def payload_bytes(self):
if self.stream_id != 0x0:
raise ValueError('SETTINGS frames MUST NOT be associated with a stream.')
b = b''
for identifier, value in self.settings.items():
b += struct.pack("!HL", identifier & 0xFF, value)
return b
class PushPromiseFrame(Frame):
TYPE = 0x5
VALID_FLAGS = [Frame.FLAG_END_HEADERS, Frame.FLAG_PADDED]
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, promised_stream=0x0, header_block_fragment=b'', pad_length=0):
super(PushPromiseFrame, self).__init__(length, flags, stream_id)
self.pad_length = pad_length
self.promised_stream = promised_stream
self.header_block_fragment = header_block_fragment
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
if f.flags & self.FLAG_PADDED:
f.pad_length, f.promised_stream = struct.unpack('!BL', payload[:5])
f.header_block_fragment = payload[5:-f.pad_length]
else:
f.promised_stream = int(struct.unpack("!L", payload[:4])[0])
f.header_block_fragment = payload[4:]
f.promised_stream &= 0x7FFFFFFF
return f
def payload_bytes(self):
if self.stream_id == 0x0:
raise ValueError('PUSH_PROMISE frames MUST be associated with a stream.')
if self.promised_stream == 0x0:
raise ValueError('Promised stream id not valid.')
b = b''
if self.flags & self.FLAG_PADDED:
b += struct.pack('!B', self.pad_length)
b += struct.pack('!L', self.promised_stream & 0x7FFFFFFF)
b += bytes(self.header_block_fragment)
if self.flags & self.FLAG_PADDED:
b += b'\0' * self.pad_length
return b
class PingFrame(Frame):
TYPE = 0x6
VALID_FLAGS = [Frame.FLAG_ACK]
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, payload=b''):
super(PingFrame, self).__init__(length, flags, stream_id)
self.payload = payload
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
f.payload = payload
return f
def payload_bytes(self):
if self.stream_id != 0x0:
raise ValueError('PING frames MUST NOT be associated with a stream.')
b = self.payload[0:8]
b += b'\0' * (8 - len(b))
return b
class GoAwayFrame(Frame):
TYPE = 0x7
VALID_FLAGS = []
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, last_stream=0x0, error_code=0x0, data=b''):
super(GoAwayFrame, self).__init__(length, flags, stream_id)
self.last_stream = last_stream
self.error_code = error_code
self.data = data
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
f.last_stream, f.error_code = struct.unpack("!LL", payload[:8])
f.last_stream &= 0x7FFFFFFF
f.data = payload[8:]
return f
def payload_bytes(self):
if self.stream_id != 0x0:
raise ValueError('GOAWAY frames MUST NOT be associated with a stream.')
b = struct.pack('!LL', self.last_stream & 0x7FFFFFFF, self.error_code)
b += bytes(self.data)
return b
class WindowUpdateFrame(Frame):
TYPE = 0x8
VALID_FLAGS = []
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, window_size_increment=0x0):
super(WindowUpdateFrame, self).__init__(length, flags, stream_id)
self.window_size_increment = window_size_increment
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
f.window_size_increment = struct.unpack("!L", payload)[0]
f.window_size_increment &= 0x7FFFFFFF
return f
def payload_bytes(self):
if self.window_size_increment <= 0 or self.window_size_increment >= 2**31:
raise ValueError('Window Szie Increment MUST be greater than 0 and less than 2^31.')
return struct.pack('!L', self.window_size_increment & 0x7FFFFFFF)
class ContinuationFrame(Frame):
TYPE = 0x9
VALID_FLAGS = [Frame.FLAG_END_HEADERS]
def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, header_block_fragment=b''):
super(ContinuationFrame, self).__init__(length, flags, stream_id)
self.header_block_fragment = header_block_fragment
@classmethod
def from_bytes(self, length, flags, stream_id, payload):
f = self(length=length, flags=flags, stream_id=stream_id)
f.header_block_fragment = payload
return f
def payload_bytes(self):
if self.stream_id == 0x0:
raise ValueError('CONTINUATION frames MUST be associated with a stream.')
return self.header_block_fragment
_FRAME_CLASSES = [
DataFrame,
HeadersFrame,
PriorityFrame,
RstStreamFrame,
SettingsFrame,
PushPromiseFrame,
PingFrame,
GoAwayFrame,
WindowUpdateFrame,
ContinuationFrame
]
FRAMES = {cls.TYPE: cls for cls in _FRAME_CLASSES}
|
