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Responder/tools/MultiRelay/impacket-dev/impacket/dcerpc/v5/rpch.py

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# SECUREAUTH LABS. Copyright 2020 SecureAuth Corporation. All rights reserved.
#
# This software is provided under under a slightly modified version
# of the Apache Software License. See the accompanying LICENSE file
# for more information.
#
# Description:
# Initial [MS-RCPH] Interface implementation
#
# Authors:
# Arseniy Sharoglazov <mohemiv@gmail.com> / Positive Technologies (https://www.ptsecurity.com/)
#
import re
import binascii
from struct import unpack
from impacket import uuid, ntlm, system_errors, nt_errors, LOG
from impacket.dcerpc.v5.rpcrt import DCERPCException
from impacket.uuid import EMPTY_UUID
from impacket.http import HTTPClientSecurityProvider, AUTH_BASIC
from impacket.structure import Structure
from impacket.dcerpc.v5.rpcrt import MSRPCHeader, \
MSRPC_RTS, PFC_FIRST_FRAG, PFC_LAST_FRAG
class RPCProxyClientException(DCERPCException):
parser = re.compile(r'RPC Error: ([a-fA-F0-9]{1,8})')
def __init__(self, error_string=None, proxy_error=None):
rpc_error_code = None
if proxy_error is not None:
try:
search = self.parser.search(proxy_error)
rpc_error_code = int(search.group(1), 16)
except:
error_string += ': ' + proxy_error
DCERPCException.__init__(self, error_string, rpc_error_code)
def __str__(self):
if self.error_code is not None:
key = self.error_code
if key in system_errors.ERROR_MESSAGES:
error_msg_short = system_errors.ERROR_MESSAGES[key][0]
return '%s, code: 0x%x - %s' % (self.error_string, self.error_code, error_msg_short)
elif key in nt_errors.ERROR_MESSAGES:
error_msg_short = nt_errors.ERROR_MESSAGES[key][0]
return '%s, code: 0x%x - %s' % (self.error_string, self.error_code, error_msg_short)
else:
return '%s: unknown code: 0x%x' % (self.error_string, self.error_code)
else:
return self.error_string
################################################################################
# CONSTANTS
################################################################################
RPC_OVER_HTTP_v1 = 1
RPC_OVER_HTTP_v2 = 2
# Errors which might need handling
# RPCProxyClient internal errors
RPC_PROXY_REMOTE_NAME_NEEDED_ERR = 'Basic authentication in RPC proxy is used, ' \
'so coudn\'t obtain a target NetBIOS name from NTLMSSP to connect.'
# Errors below contain a part of server responses
RPC_PROXY_INVALID_RPC_PORT_ERR = 'Invalid RPC Port'
RPC_PROXY_CONN_A1_0X6BA_ERR = 'RPC Proxy CONN/A1 request failed, code: 0x6ba'
RPC_PROXY_CONN_A1_404_ERR = 'CONN/A1 request failed: HTTP/1.1 404 Not Found'
RPC_PROXY_RPC_OUT_DATA_404_ERR = 'RPC_OUT_DATA channel: HTTP/1.1 404 Not Found'
RPC_PROXY_CONN_A1_401_ERR = 'CONN/A1 request failed: HTTP/1.1 401 Unauthorized'
RPC_PROXY_HTTP_IN_DATA_401_ERR = 'RPC_IN_DATA channel: HTTP/1.1 401 Unauthorized'
# 2.2.3.3 Forward Destinations
FDClient = 0x00000000
FDInProxy = 0x00000001
FDServer = 0x00000002
FDOutProxy = 0x00000003
RTS_FLAG_NONE = 0x0000
RTS_FLAG_PING = 0x0001
RTS_FLAG_OTHER_CMD = 0x0002
RTS_FLAG_RECYCLE_CHANNEL = 0x0004
RTS_FLAG_IN_CHANNEL = 0x0008
RTS_FLAG_OUT_CHANNEL = 0x0010
RTS_FLAG_EOF = 0x0020
RTS_FLAG_ECHO = 0x0040
# 2.2.3.5 RTS Commands
RTS_CMD_RECEIVE_WINDOW_SIZE = 0x00000000
RTS_CMD_FLOW_CONTROL_ACK = 0x00000001
RTS_CMD_CONNECTION_TIMEOUT = 0x00000002
RTS_CMD_COOKIE = 0x00000003
RTS_CMD_CHANNEL_LIFETIME = 0x00000004
RTS_CMD_CLIENT_KEEPALIVE = 0x00000005
RTS_CMD_VERSION = 0x00000006
RTS_CMD_EMPTY = 0x00000007
RTS_CMD_PADDING = 0x00000008
RTS_CMD_NEGATIVE_ANCE = 0x00000009
RTS_CMD_ANCE = 0x0000000A
RTS_CMD_CLIENT_ADDRESS = 0x0000000B
RTS_CMD_ASSOCIATION_GROUP_ID = 0x0000000C
RTS_CMD_DESTINATION = 0x0000000D
RTS_CMD_PING_TRAFFIC_SENT_NOTIFY = 0x0000000E
################################################################################
# STRUCTURES
################################################################################
# 2.2.3.1 RTS Cookie
class RTSCookie(Structure):
structure = (
('Cookie','16s=b"\\x00"*16'),
)
# 2.2.3.2 Client Address
class EncodedClientAddress(Structure):
structure = (
('AddressType','<L=(0 if len(ClientAddress) == 4 else 1)'),
('_ClientAddress','_-ClientAddress','4 if AddressType == 0 else 16'),
('ClientAddress',':'),
('Padding','12s=b"\\x00"*12'),
)
# 2.2.3.4 Flow Control Acknowledgment
class Ack(Structure):
structure = (
('BytesReceived','<L=0'),
('AvailableWindow','<L=0'),
('ChannelCookie',':',RTSCookie),
)
# 2.2.3.5.1 ReceiveWindowSize
class ReceiveWindowSize(Structure):
structure = (
('CommandType','<L=0'),
('ReceiveWindowSize','<L=262144'),
)
# 2.2.3.5.2 FlowControlAck
class FlowControlAck(Structure):
structure = (
('CommandType','<L=1'),
('Ack',':',Ack),
)
# 2.2.3.5.3 ConnectionTimeout
class ConnectionTimeout(Structure):
structure = (
('CommandType','<L=2'),
('ConnectionTimeout','<L=120000'),
)
# 2.2.3.5.4 Cookie
class Cookie(Structure):
structure = (
('CommandType','<L=3'),
('Cookie',':',RTSCookie),
)
# 2.2.3.5.5 ChannelLifetime
class ChannelLifetime(Structure):
structure = (
('CommandType','<L=4'),
('ChannelLifetime','<L=1073741824'),
)
# 2.2.3.5.6 ClientKeepalive
#
# By the spec, ClientKeepalive value can be 0 or in the inclusive
# range of 60,000 through 4,294,967,295.
# If it is 0, it MUST be interpreted as 300,000.
#
# But do not set it to 0, it will cause 0x6c0 rpc error.
class ClientKeepalive(Structure):
structure = (
('CommandType','<L=5'),
('ClientKeepalive','<L=300000'),
)
# 2.2.3.5.7 Version
class Version(Structure):
structure = (
('CommandType','<L=6'),
('Version','<L=1'),
)
# 2.2.3.5.8 Empty
class Empty(Structure):
structure = (
('CommandType','<L=7'),
)
# 2.2.3.5.9 Padding
class Padding(Structure):
structure = (
('CommandType','<L=8'),
('ConformanceCount','<L=len(Padding)'),
('Padding','*ConformanceCount'),
)
# 2.2.3.5.10 NegativeANCE
class NegativeANCE(Structure):
structure = (
('CommandType','<L=9'),
)
# 2.2.3.5.11 ANCE
class ANCE(Structure):
structure = (
('CommandType','<L=0xA'),
)
# 2.2.3.5.12 ClientAddress
class ClientAddress(Structure):
structure = (
('CommandType','<L=0xB'),
('ClientAddress',':',EncodedClientAddress),
)
# 2.2.3.5.13 AssociationGroupId
class AssociationGroupId(Structure):
structure = (
('CommandType','<L=0xC'),
('AssociationGroupId',':',RTSCookie),
)
# 2.2.3.5.14 Destination
class Destination(Structure):
structure = (
('CommandType','<L=0xD'),
('Destination','<L'),
)
# 2.2.3.5.15 PingTrafficSentNotify
class PingTrafficSentNotify(Structure):
structure = (
('CommandType','<L=0xE'),
('PingTrafficSent','<L'),
)
COMMANDS = {
0x0: ReceiveWindowSize,
0x1: FlowControlAck,
0x2: ConnectionTimeout,
0x3: Cookie,
0x4: ChannelLifetime,
0x5: ClientKeepalive,
0x6: Version,
0x7: Empty,
0x8: Padding,
0x9: NegativeANCE,
0xA: ANCE,
0xB: ClientAddress,
0xC: AssociationGroupId,
0xD: Destination,
0xE: PingTrafficSentNotify,
}
# 2.2.3.6.1 RTS PDU Header
# The RTS PDU Header has the same layout as the common header of
# the connection-oriented RPC PDU as specified in [C706] section 12.6.1,
# with a few additional requirements around the contents of the header fields.
class RTSHeader(MSRPCHeader):
_SIZE = 20
commonHdr = MSRPCHeader.commonHdr + (
('Flags','<H=0'), # 16
('NumberOfCommands','<H=0'), # 18
)
def __init__(self, data=None, alignment=0):
MSRPCHeader.__init__(self, data, alignment)
self['type'] = MSRPC_RTS
self['flags'] = PFC_FIRST_FRAG | PFC_LAST_FRAG
self['auth_length'] = 0
self['call_id'] = 0
# 2.2.4.2 CONN/A1 RTS PDU
#
# The CONN/A1 RTS PDU MUST be sent from the client to the outbound proxy on the OUT channel to
# initiate the establishment of a virtual connection.
class CONN_A1_RTS_PDU(Structure):
structure = (
('Version',':',Version),
('VirtualConnectionCookie',':',Cookie),
('OutChannelCookie',':',Cookie),
('ReceiveWindowSize',':',ReceiveWindowSize),
)
# 2.2.4.5 CONN/B1 RTS PDU
#
# The CONN/B1 RTS PDU MUST be sent from the client to the inbound proxy on the IN channel to
# initiate the establishment of a virtual connection.
class CONN_B1_RTS_PDU(Structure):
structure = (
('Version',':',Version),
('VirtualConnectionCookie',':',Cookie),
('INChannelCookie',':',Cookie),
('ChannelLifetime',':',ChannelLifetime),
('ClientKeepalive',':',ClientKeepalive),
('AssociationGroupId',':',AssociationGroupId),
)
# 2.2.4.4 CONN/A3 RTS PDU
#
# The CONN/A3 RTS PDU MUST be sent from the outbound proxy to the client on the OUT channel to
# continue the establishment of the virtual connection.
class CONN_A3_RTS_PDU(Structure):
structure = (
('ConnectionTimeout',':',ConnectionTimeout),
)
# 2.2.4.9 CONN/C2 RTS PDU
#
# The CONN/C2 RTS PDU MUST be sent from the outbound proxy to the client on the OUT channel to
# notify it that a virtual connection has been established.
class CONN_C2_RTS_PDU(Structure):
structure = (
('Version',':',Version),
('ReceiveWindowSize',':',ReceiveWindowSize),
('ConnectionTimeout',':',ConnectionTimeout),
)
# 2.2.4.51 FlowControlAckWithDestination RTS PDU
class FlowControlAckWithDestination_RTS_PDU(Structure):
structure = (
('Destination',':',Destination),
('FlowControlAck',':',FlowControlAck),
)
################################################################################
# HELPERS
################################################################################
def hCONN_A1(virtualConnectionCookie=EMPTY_UUID, outChannelCookie=EMPTY_UUID, receiveWindowSize=262144):
conn_a1 = CONN_A1_RTS_PDU()
conn_a1['Version'] = Version()
conn_a1['VirtualConnectionCookie'] = Cookie()
conn_a1['VirtualConnectionCookie']['Cookie'] = virtualConnectionCookie
conn_a1['OutChannelCookie'] = Cookie()
conn_a1['OutChannelCookie']['Cookie'] = outChannelCookie
conn_a1['ReceiveWindowSize'] = ReceiveWindowSize()
conn_a1['ReceiveWindowSize']['ReceiveWindowSize'] = receiveWindowSize
packet = RTSHeader()
packet['Flags'] = RTS_FLAG_NONE
packet['NumberOfCommands'] = len(conn_a1.structure)
packet['pduData'] = conn_a1.getData()
return packet.getData()
def hCONN_B1(virtualConnectionCookie=EMPTY_UUID, inChannelCookie=EMPTY_UUID, associationGroupId=EMPTY_UUID):
conn_b1 = CONN_B1_RTS_PDU()
conn_b1['Version'] = Version()
conn_b1['VirtualConnectionCookie'] = Cookie()
conn_b1['VirtualConnectionCookie']['Cookie'] = virtualConnectionCookie
conn_b1['INChannelCookie'] = Cookie()
conn_b1['INChannelCookie']['Cookie'] = inChannelCookie
conn_b1['ChannelLifetime'] = ChannelLifetime()
conn_b1['ClientKeepalive'] = ClientKeepalive()
conn_b1['AssociationGroupId'] = AssociationGroupId()
conn_b1['AssociationGroupId']['AssociationGroupId'] = RTSCookie()
conn_b1['AssociationGroupId']['AssociationGroupId']['Cookie'] = associationGroupId
packet = RTSHeader()
packet['Flags'] = RTS_FLAG_NONE
packet['NumberOfCommands'] = len(conn_b1.structure)
packet['pduData'] = conn_b1.getData()
return packet.getData()
def hFlowControlAckWithDestination(destination, bytesReceived, availableWindow, channelCookie):
rts_pdu = FlowControlAckWithDestination_RTS_PDU()
rts_pdu['Destination'] = Destination()
rts_pdu['Destination']['Destination'] = destination
rts_pdu['FlowControlAck'] = FlowControlAck()
rts_pdu['FlowControlAck']['Ack'] = Ack()
rts_pdu['FlowControlAck']['Ack']['BytesReceived'] = bytesReceived
rts_pdu['FlowControlAck']['Ack']['AvailableWindow'] = availableWindow
# Cookie of the channel for which the traffic received is being acknowledged
rts_pdu['FlowControlAck']['Ack']['ChannelCookie'] = RTSCookie()
rts_pdu['FlowControlAck']['Ack']['ChannelCookie']['Cookie'] = channelCookie
packet = RTSHeader()
packet['Flags'] = RTS_FLAG_OTHER_CMD
packet['NumberOfCommands'] = len(rts_pdu.structure)
packet['pduData'] = rts_pdu.getData()
return packet.getData()
def hPing():
packet = RTSHeader()
packet['Flags'] = RTS_FLAG_PING
return packet.getData()
################################################################################
# CLASSES
################################################################################
class RPCProxyClient(HTTPClientSecurityProvider):
RECV_SIZE = 8192
default_headers = {'User-Agent' : 'MSRPC',
'Cache-Control': 'no-cache',
'Connection' : 'Keep-Alive',
'Expect' : '100-continue',
'Accept' : 'application/rpc',
'Pragma' : 'No-cache'
}
def __init__(self, remoteName=None, dstport=593):
HTTPClientSecurityProvider.__init__(self)
self.__remoteName = remoteName
self.__dstport = dstport
# Chosen auth type
self.__auth_type = None
self.init_state()
def init_state(self):
self.__channels = {}
self.__inChannelCookie = uuid.generate()
self.__outChannelCookie = uuid.generate()
self.__associationGroupId = uuid.generate()
self.__virtualConnectionCookie = uuid.generate()
self.__serverConnectionTimeout = None
self.__serverReceiveWindowSize = None
self.__availableWindowAdvertised = 262144 # 256k
self.__receiverAvailableWindow = self.__availableWindowAdvertised
self.__bytesReceived = 0
self.__serverChunked = False
self.__readBuffer = b''
self.__chunkLeft = 0
self.rts_ping_received = False
def set_proxy_credentials(self, username, password, domain='', lmhash='', nthash=''):
LOG.error("DeprecationWarning: Call to deprecated method set_proxy_credentials (use set_credentials).")
self.set_credentials(username, password, domain, lmhash, nthash)
def set_credentials(self, username, password, domain='', lmhash='', nthash='', aesKey='', TGT=None, TGS=None):
HTTPClientSecurityProvider.set_credentials(self, username, password,
domain, lmhash, nthash, aesKey, TGT, TGS)
def create_rpc_in_channel(self):
headers = self.default_headers.copy()
headers['Content-Length'] = '1073741824'
self.create_channel('RPC_IN_DATA', headers)
def create_rpc_out_channel(self):
headers = self.default_headers.copy()
headers['Content-Length'] = '76'
self.create_channel('RPC_OUT_DATA', headers)
def create_channel(self, method, headers):
self.__channels[method] = HTTPClientSecurityProvider.connect(self, self._rpcProxyUrl.scheme,
self._rpcProxyUrl.netloc)
auth_headers = HTTPClientSecurityProvider.get_auth_headers(self, self.__channels[method],
method, self._rpcProxyUrl.path, headers)[0]
headers_final = {}
headers_final.update(headers)
headers_final.update(auth_headers)
self.__auth_type = HTTPClientSecurityProvider.get_auth_type(self)
# To connect to an RPC Server, we need to let the RPC Proxy know
# where to connect. The target RPC Server name and its port are passed
# in the query of the HTTP request. The target RPC Server must be the ncacn_http
# service.
#
# The utilized format: /rpc/rpcproxy.dll?RemoteName:RemotePort
#
# For RDG servers, you can specify localhost:3388, but in other cases you cannot
# use localhost as there will be no ACL for it.
#
# To know what RemoteName to use, we rely on Default ACL. It's specified
# in the HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy key:
#
# ValidPorts REG_SZ COMPANYSERVER04:593;COMPANYSERVER04:49152-65535
#
# In this way, we can at least connect to the endpoint mapper on port 593.
# So, if the caller set remoteName to an empty string, we assume the target
# is the RPC Proxy server itself, and get its NetBIOS name from the NTLMSSP.
#
# Interestingly, if the administrator renames the server after RPC Proxy installation
# or joins the server to the domain after RPC Proxy installation, the ACL will remain
# the original. So, sometimes the ValidPorts values have the format WIN-JCKEDQVDOQU, and
# we are not able to use them.
#
# For Exchange servers, the value of the default ACL doesn't matter as they
# allow connections by their own mechanisms:
# - Exchange 2003 / 2007 / 2010 servers add their own ACL, which includes
# NetBIOS names of all Exchange servers (and some other servers).
# This ACL is regularly and automatically updated on each server.
# Allowed ports: 6001-6004
#
# 6001 is used for MS-OXCRPC
# 6002 is used for MS-OXABREF
# 6003 is not used
# 6004 is used for MS-OXNSPI
#
# Tests on Exchange 2010 show that MS-OXNSPI and MS-OXABREF are available
# on both 6002 and 6004.
#
# - Exchange 2013 / 2016 / 2019 servers process RemoteName on their own
# (via RpcProxyShim.dll), and the NetBIOS name format is supported only for
# backward compatibility.
#
# ! Default ACL is never used, so there is no way to connect to the endpoint mapper!
#
# Allowed ports: 6001-6004
#
# 6001 is used for MS-OXCRPC
# 6002 is used for MS-OXABREF
# 6003 is not used
# 6004 is used for MS-OXNSPI
#
# Tests show that all protocols are available on the 6001 / 6002 / 6004 ports via
# RPC over HTTP v2, and the separation is only used for backward compatibility.
#
# The pure ncacn_http endpoint is available only on the 6001 TCP/IP port.
#
# RpcProxyShim.dll allows you to skip authentication on the RPC level to get
# a faster connection, and it makes Exchange 2013 / 2016 / 2019 RPC over HTTP v2
# endpoints vulnerable to NTLM-Relaying attacks.
#
# If the target is Exchange behind Microsoft TMG, you most likely need to specify
# the remote name manually using the value from /autodiscover/autodiscover.xml.
# Note that /autodiscover/autodiscover.xml might not be available with
# a non-outlook User-Agent.
#
# There may be multiple RPC Proxy servers with different NetBIOS names on
# a single external IP. We store the first one's NetBIOS name and use it for all
# the following channels.
# It's acceptable to assume all RPC Proxies have the same ACLs (true for Exchange).
if not self.__remoteName and self.__auth_type == AUTH_BASIC:
raise RPCProxyClientException(RPC_PROXY_REMOTE_NAME_NEEDED_ERR)
if not self.__remoteName:
ntlmssp = self.get_ntlmssp_info()
self.__remoteName = ntlmssp[ntlm.NTLMSSP_AV_HOSTNAME][1].decode('utf-16le')
self._stringbinding.set_network_address(self.__remoteName)
LOG.debug('StringBinding has been changed to %s' % self._stringbinding)
if not self._rpcProxyUrl.query:
query = self.__remoteName + ':' + str(self.__dstport)
self._rpcProxyUrl = self._rpcProxyUrl._replace(query=query)
path = self._rpcProxyUrl.path + '?' + self._rpcProxyUrl.query
self.__channels[method].request(method, path, headers=headers_final)
self._read_100_continue(method)
def _read_100_continue(self, method):
resp = self.__channels[method].sock.recv(self.RECV_SIZE)
while resp.find(b'\r\n\r\n') == -1:
resp += self.__channels[method].sock.recv(self.RECV_SIZE)
# Continue responses can have multiple lines, for example:
#
# HTTP/1.1 100 Continue
# Via: 1.1 FIREWALL1
#
# Don't expect the response to contain "100 Continue\r\n\r\n"
if resp[9:23] != b'100 Continue\r\n':
try:
# The server (IIS) may return localized error messages in
# the first line. Tests shown they are in UTF-8.
resp = resp.split(b'\r\n')[0].decode("UTF-8", errors='replace')
raise RPCProxyClientException('RPC Proxy Client: %s authentication failed in %s channel' %
(self.__auth_type, method), proxy_error=resp)
except (IndexError, KeyError, AttributeError):
raise RPCProxyClientException('RPC Proxy Client: %s authentication failed in %s channel' %
(self.__auth_type, method))
def create_tunnel(self):
# 3.2.1.5.3.1 Connection Establishment
packet = hCONN_A1(self.__virtualConnectionCookie, self.__outChannelCookie, self.__availableWindowAdvertised)
self.get_socket_out().send(packet)
packet = hCONN_B1(self.__virtualConnectionCookie, self.__inChannelCookie, self.__associationGroupId)
self.get_socket_in().send(packet)
resp = self.get_socket_out().recv(self.RECV_SIZE)
while resp.find(b'\r\n\r\n') == -1:
resp += self.get_socket_out().recv(self.RECV_SIZE)
if resp[9:12] != b'200':
try:
# The server (IIS) may return localized error messages in
# the first line. Tests shown they are in UTF-8.
resp = resp.split(b'\r\n')[0].decode("UTF-8", errors='replace')
raise RPCProxyClientException('RPC Proxy CONN/A1 request failed', proxy_error=resp)
except (IndexError, KeyError, AttributeError):
raise RPCProxyClientException('RPC Proxy CONN/A1 request failed')
if b'Transfer-Encoding: chunked' in resp:
self.__serverChunked = True
# If the body is here, let's send it to rpc_out_recv1()
self.__readBuffer = resp[resp.find(b'\r\n\r\n') + 4:]
# Recieving and parsing CONN/A3
conn_a3_rpc = self.rpc_out_read_pkt()
conn_a3_pdu = RTSHeader(conn_a3_rpc)['pduData']
conn_a3 = CONN_A3_RTS_PDU(conn_a3_pdu)
self.__serverConnectionTimeout = conn_a3['ConnectionTimeout']['ConnectionTimeout']
# Recieving and parsing CONN/C2
conn_c2_rpc = self.rpc_out_read_pkt()
conn_c2_pdu = RTSHeader(conn_c2_rpc)['pduData']
conn_c2 = CONN_C2_RTS_PDU(conn_c2_pdu)
self.__serverReceiveWindowSize = conn_c2['ReceiveWindowSize']['ReceiveWindowSize']
def get_socket_in(self):
return self.__channels['RPC_IN_DATA'].sock
def get_socket_out(self):
return self.__channels['RPC_OUT_DATA'].sock
def close_rpc_in_channel(self):
return self.__channels['RPC_IN_DATA'].close()
def close_rpc_out_channel(self):
return self.__channels['RPC_OUT_DATA'].close()
def check_http_error(self, buffer):
if buffer[:22] == b'HTTP/1.0 503 RPC Error':
raise RPCProxyClientException('RPC Proxy request failed', proxy_error=buffer)
def rpc_out_recv1(self, amt=None):
# Read with at most one underlying system call.
# The function MUST return the maximum amt bytes.
#
# Strictly speaking, it may cause more than one read,
# but that is ok, since that is to satisfy the chunked protocol.
sock = self.get_socket_out()
if self.__serverChunked is False:
if len(self.__readBuffer) > 0:
buffer = self.__readBuffer
self.__readBuffer = b''
else:
# Let's read RECV_SIZE bytes and not amt bytes.
# We would need to check the answer for HTTP errors, as
# they can just appear in the middle of the stream.
buffer = sock.recv(self.RECV_SIZE)
self.check_http_error(buffer)
if len(buffer) <= amt:
return buffer
# We received more than we need
self.__readBuffer = buffer[amt:]
return buffer[:amt]
# Check if the previous chunk is still there
if self.__chunkLeft > 0:
# If the previous chunk is still there,
# just give the caller what we already have
if amt >= self.__chunkLeft:
buffer = self.__readBuffer[:self.__chunkLeft]
# We may have recieved a part of a new chunk
self.__readBuffer = self.__readBuffer[self.__chunkLeft + 2:]
self.__chunkLeft = 0
return buffer
else:
buffer = self.__readBuffer[:amt]
self.__readBuffer = self.__readBuffer[amt:]
self.__chunkLeft -= amt
return buffer
# Let's start to process a new chunk
buffer = self.__readBuffer
self.__readBuffer = b''
self.check_http_error(buffer)
# Let's receive a chunk size field which ends with CRLF
# For Microsoft TMG 2010 it can cause more than one read
while buffer.find(b'\r\n') == -1:
buffer += sock.recv(self.RECV_SIZE)
self.check_http_error(buffer)
chunksize = int(buffer[:buffer.find(b'\r\n')], 16)
buffer = buffer[buffer.find(b'\r\n') + 2:]
# Let's read at least our chunk including final CRLF
while len(buffer) - 2 < chunksize:
buffer += sock.recv(chunksize - len(buffer) + 2)
# We should not be using any information from
# the TCP level to determine HTTP boundaries.
# So, we may have received more than we need.
if len(buffer) - 2 > chunksize:
self.__readBuffer = buffer[chunksize + 2:]
buffer = buffer[:chunksize + 2]
# Checking the amt
if len(buffer) - 2 > amt:
self.__chunkLeft = chunksize - amt
# We may have recieved a part of a new chunk before,
# so the concatenation is crucual
self.__readBuffer = buffer[amt:] + self.__readBuffer
return buffer[:amt]
else:
# Removing CRLF
return buffer[:-2]
def send(self, data, forceWriteAndx=0, forceRecv=0):
# We don't use chunked encoding for IN channel as
# Microsoft software is developed this way.
# If you do this, it may fail.
self.get_socket_in().send(data)
def rpc_out_read_pkt(self, handle_rts=False):
while True:
response_data = b''
# Let's receive common RPC header and no more
#
# C706
# 12.4 Common Fields
# Header encodings differ between connectionless and connection-oriented PDUs.
# However, certain fields use common sets of values with a consistent
# interpretation across the two protocols.
#
# This MUST recv MSRPCHeader._SIZE bytes, and not MSRPCRespHeader._SIZE bytes!
#
while len(response_data) < MSRPCHeader._SIZE:
response_data += self.rpc_out_recv1(MSRPCHeader._SIZE - len(response_data))
response_header = MSRPCHeader(response_data)
# frag_len contains the full length of the packet for both
# MSRPC and RTS
frag_len = response_header['frag_len']
# Receiving the full pkt and no more
while len(response_data) < frag_len:
response_data += self.rpc_out_recv1(frag_len - len(response_data))
# We need to do the Flow Control procedures
#
# 3.2.1.1.4
# This protocol specifies that only RPC PDUs are subject to the flow control abstract data
# model. RTS PDUs and the HTTP request and response headers are not subject to flow control.
if response_header['type'] != MSRPC_RTS:
self.flow_control(frag_len)
if handle_rts is True and response_header['type'] == MSRPC_RTS:
self.handle_out_of_sequence_rts(response_data)
else:
return response_data
def recv(self, forceRecv=0, count=0):
return self.rpc_out_read_pkt(handle_rts=True)
def handle_out_of_sequence_rts(self, response_data):
packet = RTSHeader(response_data)
#print("=========== RTS PKT ===========")
#print("RAW: %s" % binascii.hexlify(response_data))
#packet.dump()
#
#pduData = packet['pduData']
#numberOfCommands = packet['NumberOfCommands']
#
#server_cmds = []
#while numberOfCommands > 0:
# numberOfCommands -= 1
#
# cmd_type = unpack('<L', pduData[:4])[0]
# cmd = COMMANDS[cmd_type](pduData)
# server_cmds.append(cmd)
# pduData = pduData[len(cmd):]
#
#for cmd in server_cmds:
# cmd.dump()
#print("=========== / RTS PKT ===========")
# 2.2.4.49 Ping RTS PDU
if packet['Flags'] == RTS_FLAG_PING:
# 3.2.1.2.1 PingTimer
#
# If the SendingChannel is part of a Virtual Connection in the Outbound Proxy or Client roles, the
# SendingChannel maintains a PingTimer that on expiration indicates a PING PDU must be sent to the
# receiving channel. The PING PDU is sent to the receiving channel when no data has been sent within
# half of the value of the KeepAliveInterval.
# As we do not do long-term connections with no data transfer,
# it means something on the server-side is going wrong.
self.rts_ping_received = True
LOG.error("Ping RTS PDU packet received. Is the RPC Server alive?")
# Just in case it's a long operation, let's send PING PDU to IN Channel like in xfreerdp
# It's better to send more than one PING packet as it only 20 bytes long
packet = hPing()
self.send(packet)
self.send(packet)
# 2.2.4.24 OUT_R1/A2 RTS PDU
elif packet['Flags'] == RTS_FLAG_RECYCLE_CHANNEL:
raise RPCProxyClientException("The server requested recycling of a virtual OUT channel, " \
"but this function is not supported!")
# Ignore all other messages, most probably flow control acknowledgments
else:
pass
def flow_control(self, frag_len):
self.__bytesReceived += frag_len
self.__receiverAvailableWindow -= frag_len
if (self.__receiverAvailableWindow < self.__availableWindowAdvertised // 2):
self.__receiverAvailableWindow = self.__availableWindowAdvertised
packet = hFlowControlAckWithDestination(FDOutProxy, self.__bytesReceived,
self.__availableWindowAdvertised, self.__outChannelCookie)
self.send(packet)
def connect(self):
self.create_rpc_in_channel()
self.create_rpc_out_channel()
self.create_tunnel()
def disconnect(self):
self.close_rpc_in_channel()
self.close_rpc_out_channel()
self.init_state()
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