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# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function
from enum import Enum
from characteristic import attributes
from construct import Container
from six import BytesIO
from . import _constructs
@attributes(['major', 'minor'])
class ProtocolVersion(object):
"""
An object representing a ProtocolVersion struct.
"""
@attributes(['gmt_unix_time', 'random_bytes'])
class Random(object):
"""
An object representing a Random struct.
"""
@attributes(['type', 'data'])
class Extension(object):
"""
An object representing an Extension struct.
"""
def as_bytes(self):
return _constructs.Extension.build(Container(
type=self.type.value, length=len(self.data), data=self.data))
@attributes(['client_version', 'random', 'session_id', 'cipher_suites',
'compression_methods', 'extensions'])
class ClientHello(object):
"""
An object representing a ClientHello message.
"""
def as_bytes(self):
return _constructs.ClientHello.build(
Container(
version=Container(major=self.client_version.major,
minor=self.client_version.minor),
random=Container(
gmt_unix_time=self.random.gmt_unix_time,
random_bytes=self.random.random_bytes
),
session_id=Container(length=len(self.session_id),
session_id=self.session_id),
cipher_suites=Container(length=len(self.cipher_suites) * 2,
cipher_suites=self.cipher_suites),
compression_methods=Container(
length=len(self.compression_methods),
compression_methods=self.compression_methods
),
extensions_length=sum([2 + 2 + len(ext.data)
for ext in self.extensions]),
extensions_bytes=b''.join(
[ext.as_bytes() for ext in self.extensions]
)
)
)
@classmethod
def from_bytes(cls, bytes):
"""
Parse a ``ClientHello`` struct.
:param bytes: the bytes representing the input.
:return: ClientHello object.
"""
construct = _constructs.ClientHello.parse(bytes)
# XXX Is there a better way in Construct to parse an array of
# variable-length structs?
extensions = []
extensions_io = BytesIO(construct.extensions_bytes)
while extensions_io.tell() < construct.extensions_length:
extension_construct = _constructs.Extension.parse_stream(
extensions_io)
extensions.append(
Extension(type=ExtensionType(extension_construct.type),
data=extension_construct.data))
return ClientHello(
client_version=ProtocolVersion(
major=construct.version.major,
minor=construct.version.minor,
),
random=Random(
gmt_unix_time=construct.random.gmt_unix_time,
random_bytes=construct.random.random_bytes,
),
session_id=construct.session_id.session_id,
# TODO: cipher suites should be enums
cipher_suites=construct.cipher_suites.cipher_suites,
compression_methods=(
construct.compression_methods.compression_methods
),
extensions=extensions,
)
class ExtensionType(Enum):
SIGNATURE_ALGORITHMS = 13
# XXX: See http://tools.ietf.org/html/rfc5246#ref-TLSEXT
@attributes(['server_version', 'random', 'session_id', 'cipher_suite',
'compression_method', 'extensions'])
class ServerHello(object):
"""
An object representing a ServerHello message.
"""
def as_bytes(self):
return _constructs.ServerHello.build(
Container(
version=Container(major=self.server_version.major,
minor=self.server_version.minor),
random=Container(
gmt_unix_time=self.random.gmt_unix_time,
random_bytes=self.random.random_bytes
),
session_id=Container(length=len(self.session_id),
session_id=self.session_id),
cipher_suite=self.cipher_suite,
compression_method=self.compression_method.value,
extensions_length=sum([2 + 2 + len(ext.data)
for ext in self.extensions]),
extensions_bytes=b''.join(
[ext.as_bytes() for ext in self.extensions]
)
)
)
@classmethod
def from_bytes(cls, bytes):
"""
Parse a ``ServerHello`` struct.
:param bytes: the bytes representing the input.
:return: ServerHello object.
"""
construct = _constructs.ServerHello.parse(bytes)
# XXX: Find a better way to parse extensions
extensions = []
extensions_io = BytesIO(construct.extensions_bytes)
while extensions_io.tell() < construct.extensions_length:
extension_construct = _constructs.Extension.parse_stream(
extensions_io)
extensions.append(
Extension(type=ExtensionType(extension_construct.type),
data=extension_construct.data))
return ServerHello(
server_version=ProtocolVersion(
major=construct.version.major,
minor=construct.version.minor,
),
random=Random(
gmt_unix_time=construct.random.gmt_unix_time,
random_bytes=construct.random.random_bytes,
),
session_id=construct.session_id.session_id,
cipher_suite=construct.cipher_suite,
compression_method=CompressionMethod(construct.compression_method),
extensions=extensions,
)
class CompressionMethod(Enum):
NULL = 0
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