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_server_reconnect(self, state): """ This method gets called if a server connection needs to reconnect and there's a state associated with the server connection (e.g. a previously-sent CONNECT request or a SOCKS proxy request). This method gets called after the connection has been restablished but before SSL is established. """ 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