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+#!/usr/bin/env python
+#
+# Copyright (c) 2016, NORDUnet A/S All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+# - Redistributions of source code must retain the above copyright notice,
+# this list of conditions and the following disclaimer.
+#
+# - Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# - Neither the name of the NORDUnet nor the names of its contributors may
+# be used to endorse or promote products derived from this software
+# without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+# TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""
+Implementation of Cryptech RPC protocol multiplexer in Python.
+
+Unlike the original C implementation, this uses SLIP encapsulation
+over a SOCK_STREAM channel, because support for SOCK_SEQPACKET is not
+what we might wish. We outsource all the heavy lifting for serial and
+network I/O to the PySerial and Tornado libraries, respectively.
+"""
+
+import os
+import sys
+import time
+import struct
+import atexit
+import weakref
+import argparse
+
+import serial
+
+import tornado.tcpserver
+import tornado.iostream
+import tornado.netutil
+import tornado.ioloop
+import tornado.queues
+import tornado.locks
+import tornado.gen
+
+
+SLIP_END = chr(0300) # Indicates end of SLIP packet
+SLIP_ESC = chr(0333) # Indicates byte stuffing
+SLIP_ESC_END = chr(0334) # ESC ESC_END means END data byte
+SLIP_ESC_ESC = chr(0335) # ESC ESC_ESC means ESC data byte
+
+
+def slip_encode(buffer):
+ "Encode a buffer using SLIP encapsulation."
+ return SLIP_END + buffer.replace(SLIP_ESC, SLIP_ESC + SLIP_ESC_ESC).replace(SLIP_END, SLIP_ESC + SLIP_ESC_END) + SLIP_END
+
+def slip_decode(buffer):
+ "Decode a SLIP-encapsulated buffer."
+ return buffer.strip(SLIP_END).replace(SLIP_ESC + SLIP_ESC_END, SLIP_END).replace(SLIP_ESC + SLIP_ESC_ESC, SLIP_ESC)
+
+
+def client_handle_get(msg):
+ "Extract client_handle field from a Cryptech RPC message."
+ return struct.unpack(">L", msg[4:8])[0]
+
+def client_handle_set(msg, handle):
+ "Replace client_handle field in a Cryptech RPC message."
+ return msg[:4] + struct.pack(">L", handle) + msg[8:]
+
+
+class SerialIOStream(tornado.iostream.BaseIOStream):
+ """
+ Implementation of a Tornado IOStream over a PySerial device.
+ """
+
+ def __init__(self, device, baudrate = 921600, debug = False, *pargs, **kwargs):
+ self.serial = serial.Serial(device, baudrate, timeout = 0, write_timeout = 0)
+ self.queues = weakref.WeakValueDictionary()
+ self.debug = debug
+ self.hsm_write_lock = tornado.locks.Lock()
+ super(SerialIOStream, self).__init__(*pargs, **kwargs)
+
+ # The next four methods are required: BaseIOStream is an abstract
+ # class, we provide a driver by overriding them.
+
+ def fileno(self):
+ return self.serial.fileno()
+
+ def close_fd(self):
+ self.serial.close()
+
+ def write_to_fd(self, data):
+ return self.serial.write(data)
+
+ def read_from_fd(self):
+ return self.serial.read(self.read_chunk_size) or None
+
+ @tornado.gen.coroutine
+ def hsm_write(self, query, handle, queue):
+ "Send a query to the HSM."
+ if self.debug:
+ sys.stdout.write("+send: {}\n".format(":".join("{:02x}".format(ord(c)) for c in query)))
+ self.queues[handle] = queue
+ with (yield self.hsm_write_lock.acquire()):
+ yield self.write(query)
+
+ @tornado.gen.coroutine
+ def hsm_read_loop(self):
+ "Handle reply stream HSM -> network."
+ while True:
+ reply = yield self.read_until(SLIP_END)
+ if self.debug:
+ sys.stdout.write("+recv: {}\n".format(":".join("{:02x}".format(ord(c)) for c in reply)))
+ if len(reply) < 9:
+ continue
+ handle = client_handle_get(slip_decode(reply))
+ self.queues[handle].put_nowait(reply)
+
+
+class UnixServer(tornado.tcpserver.TCPServer):
+ """
+ Variant on tornado.tcpserver.TCPServer, listening on a PF_UNIX
+ (aka PF_LOCAL) socket instead of a TCP socket.
+ """
+
+ def listen(self, filename, mode = 0600):
+ self.add_socket(tornado.netutil.bind_unix_socket(filename, mode))
+
+ def set_serial(self, serial_stream):
+ self.serial = serial_stream
+
+ @tornado.gen.coroutine
+ def handle_stream(self, stream, address):
+ "Handle one network connection."
+ handle = stream.socket.fileno()
+ queue = tornado.queues.Queue()
+ closed = False
+ while not closed:
+ try:
+ query = yield stream.read_until(SLIP_END)
+ if len(query) < 9:
+ continue
+ query = slip_encode(client_handle_set(slip_decode(query), handle))
+ yield self.serial.hsm_write(query, handle, queue)
+ reply = yield queue.get()
+ yield stream.write(SLIP_END + reply)
+ except tornado.iostream.StreamClosedError:
+ closed = True
+
+
+parser = argparse.ArgumentParser(formatter_class = argparse.ArgumentDefaultsHelpFormatter)
+parser.add_argument("-v", "--verbose", action = "store_true", help = "produce human-readable output")
+parser.add_argument("-d", "--debug", action = "store_true", help = "blather about what we're doing")
+parser.add_argument("device", nargs = "?", help = "serial device name",
+ default = os.getenv("CRYPTECH_RPC_CLIENT_SERIAL_DEVICE", "/dev/ttyUSB0"))
+parser.add_argument("socket", nargs = "?", help = "PF_UNIX socket name",
+ default = os.getenv("CRYPTECH_RPC_CLIENT_SOCKET_NAME", "/tmp/.cryptech_rpcmuxd"))
+args = parser.parse_args()
+
+serial_stream = SerialIOStream(device = args.device, debug = args.debug)
+
+unix_server = UnixServer()
+unix_server.set_serial(serial_stream)
+unix_server.listen(args.socket)
+
+atexit.register(os.unlink, args.socket)
+
+tornado.ioloop.IOLoop.current().run_sync(serial_stream.hsm_read_loop)