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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)
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