File: //usr/lib/python3/dist-packages/rdiff_backup/connection.py
# Copyright 2002 Ben Escoto
#
# This file is part of rdiff-backup.
#
# rdiff-backup is free software; you can redistribute it and/or modify
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#
# rdiff-backup is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with rdiff-backup; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA
"""Support code for remote execution and data transfer"""
import types # noqa: F401
import os # noqa: F401
import tempfile # noqa: F401
import pickle # noqa: F401
import shutil # noqa: F401
import traceback # noqa: F401
import socket # noqa: F401
import sys # noqa: F401
import gzip # noqa: F401
# The following EA and ACL modules may be used if available
try:
import xattr.pyxattr_compat as xattr # noqa: F401
except ImportError:
try:
import xattr # noqa: F401
except ImportError:
pass
try:
import posix1e # noqa: F401
except ImportError:
pass
try:
import win32security # noqa: F401
except ImportError:
pass
class ConnectionError(Exception):
pass
class ConnectionReadError(ConnectionError):
pass
class ConnectionWriteError(ConnectionError):
pass
class ConnectionQuit(Exception):
pass
class Connection:
"""Connection class - represent remote execution
The idea is that, if c is an instance of this class, c.foo will
return the object on the remote side. For functions, c.foo will
return a function that, when called, executes foo on the remote
side, sending over the arguments and sending back the result.
"""
def __repr__(self):
return self.__str__()
def __str__(self):
return "Simple Connection" # override later
def __bool__(self):
return True
class LocalConnection(Connection):
"""Local connection
This is a dummy connection class, so that LC.foo just evaluates to
foo using global scope.
"""
def __init__(self):
"""This prevents two instances of LocalConnection"""
assert not Globals.local_connection
self.conn_number = 0 # changed by SetConnections for server
def __getattr__(self, name):
if name in globals():
return globals()[name]
elif isinstance(__builtins__, dict):
return __builtins__[name]
else:
return __builtins__.__dict__[name]
def __setattr__(self, name, value):
globals()[name] = value
def __delattr__(self, name):
del globals()[name]
def __str__(self):
return "LocalConnection"
def reval(self, function_string, *args):
return eval(function_string)(*args)
def quit(self):
pass
class ConnectionRequest:
"""Simple wrapper around a PipeConnection request"""
def __init__(self, function_string, num_args):
self.function_string = function_string
self.num_args = num_args
def __str__(self):
return "ConnectionRequest: %s with %d arguments" % \
(self.function_string, self.num_args)
class LowLevelPipeConnection(Connection):
"""Routines for just sending objects from one side of pipe to another
Each thing sent down the pipe is paired with a request number,
currently limited to be between 0 and 255. The size of each thing
should be less than 2^56.
Each thing also has a type, indicated by one of the following
characters:
o - generic object
i - iterator/generator of RORPs
f - file object
b - string
q - quit signal
R - RPath
Q - QuotedRPath
r - RORPath only
c - PipeConnection object
"""
def __init__(self, inpipe, outpipe):
"""inpipe is a file-type open for reading, outpipe for writing"""
self.inpipe = inpipe
self.outpipe = outpipe
def __str__(self):
"""Return string version
This is actually an important function, because otherwise
requests to represent this object would result in "__str__"
being executed on the other side of the connection.
"""
return "LowLevelPipeConnection"
def _put(self, obj, req_num):
"""Put an object into the pipe (will send raw if string)"""
log.Log.conn("sending", obj, req_num)
if type(obj) is bytes:
self._putbuf(obj, req_num)
elif isinstance(obj, Connection):
self._putconn(obj, req_num)
elif isinstance(obj, FilenameMapping.QuotedRPath):
self._putqrpath(obj, req_num)
elif isinstance(obj, rpath.RPath):
self._putrpath(obj, req_num)
elif isinstance(obj, rpath.RORPath):
self._putrorpath(obj, req_num)
elif ((hasattr(obj, "read") or hasattr(obj, "write"))
and hasattr(obj, "close")):
self._putfile(obj, req_num)
elif hasattr(obj, "__next__") and hasattr(obj, "__iter__"):
self._putiter(obj, req_num)
else:
self._putobj(obj, req_num)
def _putobj(self, obj, req_num):
"""Send a generic python obj down the outpipe"""
self._write("o", pickle.dumps(obj, 1), req_num)
def _putbuf(self, buf, req_num):
"""Send buffer buf down the outpipe"""
self._write("b", buf, req_num)
def _putfile(self, fp, req_num):
"""Send a file to the client using virtual files"""
self._write("f", self._i2b(VirtualFile.new(fp)), req_num)
def _putiter(self, iterator, req_num):
"""Put an iterator through the pipe"""
self._write(
"i", self._i2b(VirtualFile.new(iterfile.MiscIterToFile(iterator))),
req_num)
def _putrpath(self, rpath, req_num):
"""Put an rpath into the pipe
The rpath's connection will be encoded as its conn_number. It
and the other information is put in a tuple.
"""
rpath_repr = (rpath.conn.conn_number, rpath.base, rpath.index,
rpath.data)
self._write("R", pickle.dumps(rpath_repr, 1), req_num)
def _putqrpath(self, qrpath, req_num):
"""Put a quoted rpath into the pipe (similar to _putrpath above)"""
qrpath_repr = (qrpath.conn.conn_number, qrpath.base, qrpath.index,
qrpath.data)
self._write("Q", pickle.dumps(qrpath_repr, 1), req_num)
def _putrorpath(self, rorpath, req_num):
"""Put an rorpath into the pipe
This is only necessary because if there is a .file attached,
it must be excluded from the pickling
"""
rorpath_repr = (rorpath.index, rorpath.data)
self._write("r", pickle.dumps(rorpath_repr, 1), req_num)
def _putconn(self, pipeconn, req_num):
"""Put a connection into the pipe
A pipe connection is represented just as the integer (in
string form) of its connection number it is *connected to*.
"""
self._write("c", self._i2b(pipeconn.conn_number), req_num)
def _putquit(self):
"""Send a string that takes down server"""
self._write("q", b"", 255)
def _write(self, headerchar, data, req_num):
"""Write header and then data to the pipe"""
assert len(headerchar) == 1, \
"Header type %s can only have one letter/byte" % headerchar
if isinstance(headerchar, str): # it can only be an ASCII character
headerchar = headerchar.encode('ascii')
try:
self.outpipe.write(headerchar + self._i2b(req_num, 1) + self._i2b(len(data), 7))
self.outpipe.write(data)
self.outpipe.flush()
except (IOError, AttributeError):
raise ConnectionWriteError()
def _read(self, length):
"""Read length bytes from inpipe, returning result"""
try:
return self.inpipe.read(length)
except IOError:
raise ConnectionReadError()
def _b2i(self, b):
"""Convert bytes to int using big endian byteorder"""
return int.from_bytes(b, byteorder='big')
def _i2b(self, i, size=0):
"""Convert int to string using big endian byteorder"""
if (size == 0):
size = (i.bit_length() + 7) // 8
return i.to_bytes(size, byteorder='big')
def _get(self):
"""Read an object from the pipe and return (req_num, value)"""
header_string = self.inpipe.read(9)
if not len(header_string) == 9:
raise ConnectionReadError("Truncated header string (problem "
"probably originated remotely)")
format_string = header_string[0:1]
req_num = self._b2i(header_string[1:2])
length = self._b2i(header_string[2:])
if format_string == b"q":
raise ConnectionQuit("Received quit signal")
data = self._read(length)
if format_string == b"o":
result = pickle.loads(data)
elif format_string == b"b":
result = data
elif format_string == b"f":
result = VirtualFile(self, self._b2i(data))
elif format_string == b"i":
result = iterfile.FileToMiscIter(
VirtualFile(self, self._b2i(data)))
elif format_string == b"r":
result = self._getrorpath(data)
elif format_string == b"R":
result = self._getrpath(data)
elif format_string == b"Q":
result = self._getqrpath(data)
else:
assert format_string == b"c", header_string
result = Globals.connection_dict[self._b2i(data)]
log.Log.conn("received", result, req_num)
return (req_num, result)
def _getrorpath(self, raw_rorpath_buf):
"""Reconstruct RORPath object from raw data"""
index, data = pickle.loads(raw_rorpath_buf)
return rpath.RORPath(index, data)
def _getrpath(self, raw_rpath_buf):
"""Return RPath object indicated by raw_rpath_buf"""
conn_number, base, index, data = pickle.loads(raw_rpath_buf)
return rpath.RPath(Globals.connection_dict[conn_number], base, index,
data)
def _getqrpath(self, raw_qrpath_buf):
"""Return QuotedRPath object from raw buffer"""
conn_number, base, index, data = pickle.loads(raw_qrpath_buf)
return FilenameMapping.QuotedRPath(
Globals.connection_dict[conn_number], base, index, data)
def _close(self):
"""Close the pipes associated with the connection"""
self.outpipe.close()
self.inpipe.close()
class PipeConnection(LowLevelPipeConnection):
"""Provide server and client functions for a Pipe Connection
Both sides act as modules that allows for remote execution. For
instance, self.conn.pow(2,8) will execute the operation on the
server side.
The only difference between the client and server is that the
client makes the first request, and the server listens first.
"""
def __init__(self, inpipe, outpipe, conn_number=0):
"""Init PipeConnection
conn_number should be a unique (to the session) integer to
identify the connection. For instance, all connections to the
client have conn_number 0. Other connections can use this
number to route commands to the correct process.
"""
LowLevelPipeConnection.__init__(self, inpipe, outpipe)
self.conn_number = conn_number
self.unused_request_numbers = {}
for i in range(256):
self.unused_request_numbers[i] = None
def __str__(self):
return "PipeConnection %d" % self.conn_number
def get_response(self, desired_req_num):
"""Read from pipe, responding to requests until req_num.
Sometimes after a request is sent, the other side will make
another request before responding to the original one. In
that case, respond to the request. But return once the right
response is given.
"""
while 1:
try:
req_num, object = self._get()
except ConnectionQuit:
self._put("quitting", self.get_new_req_num())
self._close()
return
if req_num == desired_req_num:
return object
else:
assert isinstance(object, ConnectionRequest)
self.answer_request(object, req_num)
def answer_request(self, request, req_num):
"""Put the object requested by request down the pipe"""
del self.unused_request_numbers[req_num]
argument_list = []
for i in range(request.num_args):
arg_req_num, arg = self._get()
assert arg_req_num == req_num
argument_list.append(arg)
try:
Security.vet_request(request, argument_list)
result = eval(request.function_string)(*argument_list)
except BaseException:
result = self.extract_exception()
self._put(result, req_num)
self.unused_request_numbers[req_num] = None
def extract_exception(self):
"""Return active exception"""
if robust.is_routine_fatal(sys.exc_info()[1]):
raise # Fatal error--No logging necessary, but connection down
if log.Log.verbosity >= 5 or log.Log.term_verbosity >= 5:
log.Log(
"Sending back exception %s of type %s: \n%s" %
(sys.exc_info()[1], sys.exc_info()[0], "".join(
traceback.format_tb(sys.exc_info()[2]))), 5)
return sys.exc_info()[1]
def Server(self):
"""Start server's read eval return loop"""
Globals.server = 1
Globals.connections.append(self)
log.Log("Starting server", 6)
self.get_response(-1)
def reval(self, function_string, *args):
"""Execute command on remote side
The first argument should be a string that evaluates to a
function, like "pow", and the remaining are arguments to that
function.
"""
req_num = self.get_new_req_num()
self._put(ConnectionRequest(function_string, len(args)), req_num)
for arg in args:
self._put(arg, req_num)
result = self.get_response(req_num)
self.unused_request_numbers[req_num] = None
if isinstance(result, Exception):
raise result
elif isinstance(result, SystemExit):
raise result
elif isinstance(result, KeyboardInterrupt):
raise result
else:
return result
def get_new_req_num(self):
"""Allot a new request number and return it"""
if not self.unused_request_numbers:
raise ConnectionError("Exhausted possible connection numbers")
req_num = list(self.unused_request_numbers.keys())[0]
del self.unused_request_numbers[req_num]
return req_num
def quit(self):
"""Close the associated pipes and tell server side to quit"""
assert not Globals.server
self._putquit()
self._get()
self._close()
def __getattr__(self, name):
"""Intercept attributes to allow for . invocation"""
return EmulateCallable(self, name)
class RedirectedConnection(Connection):
"""Represent a connection more than one move away
For instance, suppose things are connected like this: S1---C---S2.
If Server1 wants something done by Server2, it will have to go
through the Client. So on S1's side, S2 will be represented by a
RedirectedConnection.
"""
def __init__(self, conn_number, routing_number=0):
"""RedirectedConnection initializer
Returns a RedirectedConnection object for the given
conn_number, where commands are routed through the connection
with the given routing_number. 0 is the client, so the
default shouldn't have to be changed.
"""
self.conn_number = conn_number
self.routing_number = routing_number
self.routing_conn = Globals.connection_dict[routing_number]
def reval(self, function_string, *args):
"""Evaluation function_string on args on remote connection"""
return self.routing_conn.reval("RedirectedRun", self.conn_number,
function_string, *args)
def __str__(self):
return "RedirectedConnection %d,%d" % (self.conn_number,
self.routing_number)
def __getattr__(self, name):
return EmulateCallableRedirected(self.conn_number, self.routing_conn,
name)
def RedirectedRun(conn_number, func, *args):
"""Run func with args on connection with conn number conn_number
This function is meant to redirect requests from one connection to
another, so conn_number must not be the local connection (and also
for security reasons since this function is always made
available).
"""
conn = Globals.connection_dict[conn_number]
assert conn is not Globals.local_connection, conn
return conn.reval(func, *args)
class EmulateCallable:
"""This is used by PipeConnection in calls like conn.os.chmod(foo)"""
def __init__(self, connection, name):
self.connection = connection
self.name = name
def __call__(self, *args):
return self.connection.reval(*(self.name, ) + args)
def __getattr__(self, attr_name):
return EmulateCallable(self.connection,
"%s.%s" % (self.name, attr_name))
class EmulateCallableRedirected:
"""Used by RedirectedConnection in calls like conn.os.chmod(foo)"""
def __init__(self, conn_number, routing_conn, name):
self.conn_number, self.routing_conn = conn_number, routing_conn
self.name = name
def __call__(self, *args):
return self.routing_conn.reval(
*("RedirectedRun", self.conn_number, self.name) + args)
def __getattr__(self, attr_name):
return EmulateCallableRedirected(self.conn_number, self.routing_conn,
"%s.%s" % (self.name, attr_name))
class VirtualFile:
"""When the client asks for a file over the connection, it gets this
The returned instance then forwards requests over the connection.
The class's dictionary is used by the server to associate each
with a unique file number.
"""
# The following are used by the server
vfiles = {}
counter = 0
def getbyid(cls, id):
return cls.vfiles[id]
getbyid = classmethod(getbyid)
def readfromid(cls, id, length):
if length is None:
return cls.vfiles[id].read()
else:
return cls.vfiles[id].read(length)
readfromid = classmethod(readfromid)
def readlinefromid(cls, id):
return cls.vfiles[id].readline()
readlinefromid = classmethod(readlinefromid)
def writetoid(cls, id, buffer):
return cls.vfiles[id].write(buffer)
writetoid = classmethod(writetoid)
def closebyid(cls, id):
fp = cls.vfiles[id]
del cls.vfiles[id]
return fp.close()
closebyid = classmethod(closebyid)
def new(cls, fileobj):
"""Associate a new VirtualFile with a read fileobject, return id"""
count = cls.counter
cls.vfiles[count] = fileobj
cls.counter = count + 1
return count
new = classmethod(new)
# And these are used by the client
def __init__(self, connection, id):
self.connection = connection
self.id = id
def read(self, length=None):
return self.connection.VirtualFile.readfromid(self.id, length)
def readline(self):
return self.connection.VirtualFile.readlinefromid(self.id)
def write(self, buf):
return self.connection.VirtualFile.writetoid(self.id, buf)
def close(self):
return self.connection.VirtualFile.closebyid(self.id)
def __iter__(self):
"""Iterates lines in file, like normal iter(file) behavior"""
while 1:
line = self.readline()
if not line:
break
yield line
# everything has to be available here for remote connection's use, but
# put at bottom to reduce circularities.
from . import ( # noqa: E402,F401
Globals, Time, Rdiff, Hardlink, FilenameMapping, Security,
Main, rorpiter, selection, increment, statistics, manage,
iterfile, rpath, robust, restore, backup,
TempFile, SetConnections, librsync, log, regress, fs_abilities,
eas_acls, user_group, compare
)
try:
from . import win_acls # noqa: F401
except ImportError:
pass
Globals.local_connection = LocalConnection()
Globals.connections.append(Globals.local_connection)
# Following changed by server in SetConnections
Globals.connection_dict[0] = Globals.local_connection