from __future__ import absolute_import
import copy
import uuid
import netlib.tcp
from .. import stateobject, utils, version
from ..proxy.connection import ClientConnection, ServerConnection
KILL = 0 # const for killed requests
class Error(stateobject.StateObject):
"""
An Error.
This is distinct from an protocol error response (say, a HTTP code 500),
which is represented by a normal HTTPResponse object. This class is
responsible for indicating errors that fall outside of normal protocol
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):
# the default implementation assumes an empty constructor. Override
# accordingly.
f = cls(None)
f.load_state(state)
return f
def copy(self):
c = copy.copy(self)
return c
class Flow(stateobject.StateObject):
"""
A Flow is a collection of objects representing a single transaction.
This class is usually subclassed for each protocol, e.g. HTTPFlow.
"""
def __init__(self, type, client_conn, server_conn, live=None):
self.type = type
self.id = str(uuid.uuid4())
self.client_conn = client_conn
"""@type: ClientConnection"""
self.server_conn = server_conn
"""@type: ServerConnection"""
self.live = live
"""@type: LiveConnection"""
self.error = None
"""@type: Error"""
self.intercepted = False
"""@type: bool"""
self._backup = None
self.reply = None
_stateobject_attributes = dict(
id=str,
error=Error,
client_conn=ClientConnection,
server_conn=ServerConnection,
type=str,
intercepted=bool
)
def get_state(self, short=False):
d = super(Flow, self).get_state(short)
d.update(version=version.IVERSION)
if self._backup and self._backup != d:
if short:
d.update(modified=True)
else:
d.update(backup=self._backup)
return d
def __eq__(self, other):
return self is other
def copy(self):
f = copy.copy(self)
f.id = str(uuid.uuid4())
f.live = False
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
def kill(self, master):
"""
Kill this request.
"""
self.error = Error("Connection killed")
self.intercepted = False
self.reply(KILL)
master.handle_error(self)
def intercept(self, master):
"""
Intercept this Flow. Processing will stop until accept_intercept is
called.
"""
if self.intercepted:
return
self.intercepted = True
master.handle_intercept(self)
def accept_intercept(self, master):
"""
Continue with the flow - called after an intercept().
"""
if not self.intercepted:
return
self.intercepted = False
self.reply()
master.handle_accept_intercept(self)
class ProtocolHandler(object):
"""
A ProtocolHandler implements an application-layer protocol, e.g. HTTP.
See: libmproxy.protocol.http.HTTPHandler
"""
def __init__(self, c):
self.c = c
"""@type: libmproxy.proxy.server.ConnectionHandler"""
self.live = LiveConnection(c)
"""@type: LiveConnection"""
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 LiveConnection(object):
"""
This facade allows interested parties (FlowMaster, inline scripts) to
interface with a live connection, without exposing the internals
of the ConnectionHandler.
"""
def __init__(self, c):
self.c = c
"""@type: libmproxy.proxy.server.ConnectionHandler"""
self._backup_server_conn = None
"""@type: libmproxy.proxy.connection.ServerConnection"""
def change_server(self, address, ssl=None, sni=None, force=False, persistent_change=False):
"""
Change the server connection to the specified address.
@returns:
True, if a new connection has been established,
False, if an existing connection has been used
"""
address = netlib.tcp.Address.wrap(address)
ssl_mismatch = (
ssl is not None and
(
ssl != self.c.server_conn.ssl_established
or
(sni is not None and sni != self.c.server_conn.sni)
)
)
address_mismatch = (address != self.c.server_conn.address)
if persistent_change:
self._backup_server_conn = None
if ssl_mismatch or address_mismatch or force:
self.c.log(
"Change server connection: %s:%s -> %s:%s [persistent: %s]" % (
self.c.server_conn.address.host,
self.c.server_conn.address.port,
address.host,
address.port,
persistent_change
),
"debug"
)
if not self._backup_server_conn and not persistent_change:
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)
self.c.establish_server_connection(ask=False)
if ssl:
self.c.establish_ssl(server=True, sni=sni)
return True
return False
def restore_server(self):
# TODO: Similar to _backup_server_conn, introduce _cache_server_conn,
# which keeps the changed connection open This may be beneficial if a
# user is rewriting all requests from http to https or similar.
if not 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
self._backup_server_conn = None