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from __future__ import absolute_import
import copy
import netlib.tcp
from .. import stateobject, utils, version
from ..proxy.primitives import AddressPriority
from ..proxy.connection import ClientConnection, ServerConnection
KILL = 0 # const for killed requests
class BackreferenceMixin(object):
"""
If an attribute from the _backrefattr tuple is set,
this mixin sets a reference back on the attribute object.
Example:
e = Error()
f = Flow()
f.error = e
assert f is e.flow
"""
_backrefattr = tuple()
def __setattr__(self, key, value):
super(BackreferenceMixin, self).__setattr__(key, value)
if key in self._backrefattr and value is not None:
setattr(value, self._backrefname, self)
class Error(stateobject.SimpleStateObject):
"""
An Error.
This is distinct from an HTTP error response (say, a code 500), which
is represented by a normal Response object. This class is responsible
for indicating errors that fall outside of normal HTTP communications,
like interrupted connections, timeouts, protocol errors.
Exposes the following attributes:
flow: Flow object
msg: Message describing the error
timestamp: Seconds since the epoch
"""
def __init__(self, msg, timestamp=None):
"""
@type msg: str
@type timestamp: float
"""
self.flow = None # will usually be set by the flow backref mixin
self.msg = msg
self.timestamp = timestamp or utils.timestamp()
_stateobject_attributes = dict(
msg=str,
timestamp=float
)
def __str__(self):
return self.msg
@classmethod
def _from_state(cls, state):
f = cls(None) # the default implementation assumes an empty constructor. Override accordingly.
f._load_state(state)
return f
def copy(self):
c = copy.copy(self)
return c
class Flow(stateobject.SimpleStateObject, BackreferenceMixin):
def __init__(self, conntype, client_conn, server_conn):
self.conntype = conntype
self.client_conn = client_conn
"""@type: ClientConnection"""
self.server_conn = server_conn
"""@type: ServerConnection"""
self.error = None
"""@type: Error"""
self._backup = None
_backrefattr = ("error",)
_backrefname = "flow"
_stateobject_attributes = dict(
error=Error,
client_conn=ClientConnection,
server_conn=ServerConnection,
conntype=str
)
def _get_state(self):
d = super(Flow, self)._get_state()
d.update(version=version.IVERSION)
return d
def __eq__(self, other):
return self is other
def copy(self):
f = copy.copy(self)
f.client_conn = self.client_conn.copy()
f.server_conn = self.server_conn.copy()
if self.error:
f.error = self.error.copy()
return f
def modified(self):
"""
Has this Flow been modified?
"""
if self._backup:
return self._backup != self._get_state()
else:
return False
def backup(self, force=False):
"""
Save a backup of this Flow, which can be reverted to using a
call to .revert().
"""
if not self._backup:
self._backup = self._get_state()
def revert(self):
"""
Revert to the last backed up state.
"""
if self._backup:
self._load_state(self._backup)
self._backup = None
class ProtocolHandler(object):
def __init__(self, c):
self.c = c
"""@type: libmproxy.proxy.server.ConnectionHandler"""
def handle_messages(self):
"""
This method gets called if a client connection has been made. Depending on the proxy settings,
a server connection might already exist as well.
"""
raise NotImplementedError # pragma: nocover
def handle_error(self, error):
"""
This method gets called should there be an uncaught exception during the connection.
This might happen outside of handle_messages, e.g. if the initial SSL handshake fails in transparent mode.
"""
raise error # pragma: nocover
class TemporaryServerChangeMixin(object):
"""
This mixin allows safe modification of the target server,
without any need to expose the ConnectionHandler to the Flow.
"""
def change_server(self, address, ssl):
address = netlib.tcp.Address.wrap(address)
if address == self.c.server_conn.address():
return
priority = AddressPriority.MANUALLY_CHANGED
self.c.log("Temporarily change server connection: %s:%s -> %s:%s" % (
self.c.server_conn.address.host,
self.c.server_conn.address.port,
address.host,
address.port
), "debug")
if not hasattr(self, "_backup_server_conn"):
self._backup_server_conn = self.c.server_conn
self.c.server_conn = None
else: # This is at least the second temporary change. We can kill the current connection.
self.c.del_server_connection()
self.c.set_server_address(address, priority)
self.c.establish_server_connection(ask=False)
if ssl:
self.c.establish_ssl(server=True)
def restore_server(self):
if not hasattr(self, "_backup_server_conn"):
return
self.c.log("Restore original server connection: %s:%s -> %s:%s" % (
self.c.server_conn.address.host,
self.c.server_conn.address.port,
self._backup_server_conn.address.host,
self._backup_server_conn.address.port
), "debug")
self.c.del_server_connection()
self.c.server_conn = self._backup_server_conn
del self._backup_server_conn
|
