mitmproxy/netlib/http2/frame.py
Aldo Cortesi 4152b14387 Merge pull request #71 from Kriechi/landscape
fix warnings and code smells
2015-06-18 12:07:20 +12:00

636 lines
18 KiB
Python

import sys
import struct
from hpack.hpack import Encoder, Decoder
from .. import utils
class FrameSizeError(Exception):
pass
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,
state=None,
length=0,
flags=FLAG_NO_FLAGS,
stream_id=0x0):
valid_flags = reduce(lambda x, y: x | y, self.VALID_FLAGS, 0x0)
if flags | valid_flags != valid_flags:
raise ValueError('invalid flags detected.')
if state is None:
class State(object):
pass
state = State()
state.http2_settings = HTTP2_DEFAULT_SETTINGS.copy()
state.encoder = Encoder()
state.decoder = Decoder()
self.state = state
self.length = length
self.type = self.TYPE
self.flags = flags
self.stream_id = stream_id
@classmethod
def _check_frame_size(cls, length, state):
if state:
settings = state.http2_settings
else:
settings = HTTP2_DEFAULT_SETTINGS.copy()
max_frame_size = settings[
SettingsFrame.SETTINGS.SETTINGS_MAX_FRAME_SIZE]
if length > max_frame_size:
raise FrameSizeError(
"Frame size exceeded: %d, but only %d allowed." % (
length, max_frame_size))
@classmethod
def from_file(cls, fp, state=None):
"""
read a HTTP/2 frame sent by a server or client
fp is a "file like" object that could be backed by a network
stream or a disk or an in memory stream reader
"""
raw_header = fp.safe_read(9)
fields = struct.unpack("!HBBBL", raw_header)
length = (fields[0] << 8) + fields[1]
flags = fields[3]
stream_id = fields[4]
if raw_header[:4] == b'HTTP': # pragma no cover
print >> sys.stderr, "WARNING: This looks like an HTTP/1 connection!"
cls._check_frame_size(length, state)
payload = fp.safe_read(length)
return FRAMES[fields[2]].from_bytes(
state,
length,
flags,
stream_id,
payload)
def to_bytes(self):
payload = self.payload_bytes()
self.length = len(payload)
self._check_frame_size(self.length, self.state)
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 payload_bytes(self): # pragma: no cover
raise NotImplementedError()
def payload_human_readable(self): # pragma: no cover
raise NotImplementedError()
def human_readable(self, direction="-"):
self.length = len(self.payload_bytes())
return "\n".join([
"%s: %s | length: %d | flags: %#x | stream_id: %d" % (direction, self.__class__.__name__, self.length, self.flags, self.stream_id),
self.payload_human_readable(),
"===============================================================",
])
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,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
payload=b'',
pad_length=0):
super(DataFrame, self).__init__(state, length, flags, stream_id)
self.payload = payload
self.pad_length = pad_length
@classmethod
def from_bytes(cls, state, length, flags, stream_id, payload):
f = cls(state=state, length=length, flags=flags, stream_id=stream_id)
if f.flags & Frame.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
def payload_human_readable(self):
return "payload: %s" % str(self.payload)
class HeadersFrame(Frame):
TYPE = 0x1
VALID_FLAGS = [
Frame.FLAG_END_STREAM,
Frame.FLAG_END_HEADERS,
Frame.FLAG_PADDED,
Frame.FLAG_PRIORITY]
def __init__(
self,
state=None,
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__(state, 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(cls, state, length, flags, stream_id, payload):
f = cls(state=state, length=length, flags=flags, stream_id=stream_id)
if f.flags & Frame.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 & Frame.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 += self.header_block_fragment
if self.flags & self.FLAG_PADDED:
b += b'\0' * self.pad_length
return b
def payload_human_readable(self):
s = []
if self.flags & self.FLAG_PRIORITY:
s.append("exclusive: %d" % self.exclusive)
s.append("stream dependency: %#x" % self.stream_dependency)
s.append("weight: %d" % self.weight)
if self.flags & self.FLAG_PADDED:
s.append("padding: %d" % self.pad_length)
s.append(
"header_block_fragment: %s" %
self.header_block_fragment.encode('hex'))
return "\n".join(s)
class PriorityFrame(Frame):
TYPE = 0x2
VALID_FLAGS = []
def __init__(
self,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
exclusive=False,
stream_dependency=0x0,
weight=0):
super(PriorityFrame, self).__init__(state, length, flags, stream_id)
self.exclusive = exclusive
self.stream_dependency = stream_dependency
self.weight = weight
@classmethod
def from_bytes(cls, state, length, flags, stream_id, payload):
f = cls(state=state, 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)
def payload_human_readable(self):
s = []
s.append("exclusive: %d" % self.exclusive)
s.append("stream dependency: %#x" % self.stream_dependency)
s.append("weight: %d" % self.weight)
return "\n".join(s)
class RstStreamFrame(Frame):
TYPE = 0x3
VALID_FLAGS = []
def __init__(
self,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
error_code=0x0):
super(RstStreamFrame, self).__init__(state, length, flags, stream_id)
self.error_code = error_code
@classmethod
def from_bytes(cls, state, length, flags, stream_id, payload):
f = cls(state=state, 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)
def payload_human_readable(self):
return "error code: %#x" % 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,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
settings=None):
super(SettingsFrame, self).__init__(state, length, flags, stream_id)
if settings is None:
settings = {}
self.settings = settings
@classmethod
def from_bytes(cls, state, length, flags, stream_id, payload):
f = cls(state=state, 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
def payload_human_readable(self):
s = []
for identifier, value in self.settings.items():
s.append("%s: %#x" % (self.SETTINGS.get_name(identifier), value))
if not s:
return "settings: None"
else:
return "\n".join(s)
class PushPromiseFrame(Frame):
TYPE = 0x5
VALID_FLAGS = [Frame.FLAG_END_HEADERS, Frame.FLAG_PADDED]
def __init__(
self,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
promised_stream=0x0,
header_block_fragment=b'',
pad_length=0):
super(PushPromiseFrame, self).__init__(state, 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(cls, state, length, flags, stream_id, payload):
f = cls(state=state, length=length, flags=flags, stream_id=stream_id)
if f.flags & Frame.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
def payload_human_readable(self):
s = []
if self.flags & self.FLAG_PADDED:
s.append("padding: %d" % self.pad_length)
s.append("promised stream: %#x" % self.promised_stream)
s.append(
"header_block_fragment: %s" %
self.header_block_fragment.encode('hex'))
return "\n".join(s)
class PingFrame(Frame):
TYPE = 0x6
VALID_FLAGS = [Frame.FLAG_ACK]
def __init__(
self,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
payload=b''):
super(PingFrame, self).__init__(state, length, flags, stream_id)
self.payload = payload
@classmethod
def from_bytes(cls, state, length, flags, stream_id, payload):
f = cls(state=state, 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
def payload_human_readable(self):
return "opaque data: %s" % str(self.payload)
class GoAwayFrame(Frame):
TYPE = 0x7
VALID_FLAGS = []
def __init__(
self,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
last_stream=0x0,
error_code=0x0,
data=b''):
super(GoAwayFrame, self).__init__(state, length, flags, stream_id)
self.last_stream = last_stream
self.error_code = error_code
self.data = data
@classmethod
def from_bytes(cls, state, length, flags, stream_id, payload):
f = cls(state=state, 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
def payload_human_readable(self):
s = []
s.append("last stream: %#x" % self.last_stream)
s.append("error code: %d" % self.error_code)
s.append("debug data: %s" % str(self.data))
return "\n".join(s)
class WindowUpdateFrame(Frame):
TYPE = 0x8
VALID_FLAGS = []
def __init__(
self,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
window_size_increment=0x0):
super(WindowUpdateFrame, self).__init__(state, length, flags, stream_id)
self.window_size_increment = window_size_increment
@classmethod
def from_bytes(cls, state, length, flags, stream_id, payload):
f = cls(state=state, 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)
def payload_human_readable(self):
return "window size increment: %#x" % self.window_size_increment
class ContinuationFrame(Frame):
TYPE = 0x9
VALID_FLAGS = [Frame.FLAG_END_HEADERS]
def __init__(
self,
state=None,
length=0,
flags=Frame.FLAG_NO_FLAGS,
stream_id=0x0,
header_block_fragment=b''):
super(ContinuationFrame, self).__init__(state, length, flags, stream_id)
self.header_block_fragment = header_block_fragment
@classmethod
def from_bytes(cls, state, length, flags, stream_id, payload):
f = cls(state=state, 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
def payload_human_readable(self):
s = []
s.append(
"header_block_fragment: %s" %
self.header_block_fragment.encode('hex'))
return "\n".join(s)
_FRAME_CLASSES = [
DataFrame,
HeadersFrame,
PriorityFrame,
RstStreamFrame,
SettingsFrame,
PushPromiseFrame,
PingFrame,
GoAwayFrame,
WindowUpdateFrame,
ContinuationFrame
]
FRAMES = {cls.TYPE: cls for cls in _FRAME_CLASSES}
HTTP2_DEFAULT_SETTINGS = {
SettingsFrame.SETTINGS.SETTINGS_HEADER_TABLE_SIZE: 4096,
SettingsFrame.SETTINGS.SETTINGS_ENABLE_PUSH: 1,
SettingsFrame.SETTINGS.SETTINGS_MAX_CONCURRENT_STREAMS: None,
SettingsFrame.SETTINGS.SETTINGS_INITIAL_WINDOW_SIZE: 2 ** 16 - 1,
SettingsFrame.SETTINGS.SETTINGS_MAX_FRAME_SIZE: 2 ** 14,
SettingsFrame.SETTINGS.SETTINGS_MAX_HEADER_LIST_SIZE: None,
}