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# $Id$
#
# Copyright (C) 2014 Dragon Research Labs ("DRL")
# Portions copyright (C) 2009-2013 Internet Systems Consortium ("ISC")
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notices and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND DRL AND ISC DISCLAIM ALL
# WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DRL OR
# ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
# DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA
# OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
# TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.
"""
I/O system of RPKI-RTR protocol implementation.
"""
import os
import sys
import time
import fcntl
import errno
import logging
import asyncore
import asynchat
import rpki.rtr.pdus
class Timestamp(int):
"""
Wrapper around time module.
"""
def __new__(cls, t):
# __new__() is a static method, not a class method, hence the odd calling sequence.
return super(Timestamp, cls).__new__(cls, t)
@classmethod
def now(cls, delta = 0):
return cls(time.time() + delta)
def __str__(self):
return time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime(self))
class ReadBuffer(object):
"""
Wrapper around synchronous/asynchronous read state.
This also handles tracking the current protocol version,
because it has to go somewhere and there's no better place.
"""
def __init__(self):
self.buffer = ""
self.version = None
def update(self, need, callback):
"""
Update count of needed bytes and callback, then dispatch to callback.
"""
self.need = need
self.callback = callback
return self.retry()
def retry(self):
"""
Try dispatching to the callback again.
"""
return self.callback(self)
def available(self):
"""
How much data do we have available in this buffer?
"""
return len(self.buffer)
def needed(self):
"""
How much more data does this buffer need to become ready?
"""
return self.need - self.available()
def ready(self):
"""
Is this buffer ready to read yet?
"""
return self.available() >= self.need
def get(self, n):
"""
Hand some data to the caller.
"""
b = self.buffer[:n]
self.buffer = self.buffer[n:]
return b
def put(self, b):
"""
Accumulate some data.
"""
self.buffer += b
def check_version(self, version):
"""
Track version number of PDUs read from this buffer.
Once set, the version must not change.
"""
if self.version is not None and version != self.version:
raise rpki.rtr.pdus.CorruptData(
"Received PDU version %d, expected %d" % (version, self.version))
if self.version is None and version not in rpki.rtr.pdus.PDU.version_map:
raise rpki.rtr.pdus.UnsupportedProtocolVersion(
"Received PDU version %s, known versions %s" % (
version, ", ".join(str(v) for v in rpki.rtr.pdus.PDU.version_map)))
self.version = version
class PDUChannel(asynchat.async_chat, object):
"""
asynchat subclass that understands our PDUs. This just handles
network I/O. Specific engines (client, server) should be subclasses
of this with methods that do something useful with the resulting
PDUs.
"""
def __init__(self, root_pdu_class, sock = None):
asynchat.async_chat.__init__(self, sock) # Old-style class, can't use super()
self.reader = ReadBuffer()
assert issubclass(root_pdu_class, rpki.rtr.pdus.PDU)
self.root_pdu_class = root_pdu_class
@property
def version(self):
return self.reader.version
@version.setter
def version(self, version):
self.reader.check_version(version)
def start_new_pdu(self):
"""
Start read of a new PDU.
"""
try:
p = self.root_pdu_class.read_pdu(self.reader)
while p is not None:
self.deliver_pdu(p)
p = self.root_pdu_class.read_pdu(self.reader)
except rpki.rtr.pdus.PDUException, e:
self.push_pdu(e.make_error_report(version = self.version))
self.close_when_done()
else:
assert not self.reader.ready()
self.set_terminator(self.reader.needed())
def collect_incoming_data(self, data):
"""
Collect data into the read buffer.
"""
self.reader.put(data)
def found_terminator(self):
"""
Got requested data, see if we now have a PDU. If so, pass it
along, then restart cycle for a new PDU.
"""
p = self.reader.retry()
if p is None:
self.set_terminator(self.reader.needed())
else:
self.deliver_pdu(p)
self.start_new_pdu()
def push_pdu(self, pdu):
"""
Write PDU to stream.
"""
try:
self.push(pdu.to_pdu())
except OSError, e:
if e.errno != errno.EAGAIN:
raise
def log(self, msg):
"""
Intercept asyncore's logging.
"""
logging.info(msg)
def log_info(self, msg, tag = "info"):
"""
Intercept asynchat's logging.
"""
logging.info("asynchat: %s: %s", tag, msg)
def handle_error(self):
"""
Handle errors caught by asyncore main loop.
"""
logging.exception("[Unhandled exception]")
logging.critical("[Exiting after unhandled exception]")
sys.exit(1)
def init_file_dispatcher(self, fd):
"""
Kludge to plug asyncore.file_dispatcher into asynchat. Call from
subclass's __init__() method, after calling
PDUChannel.__init__(), and don't read this on a full stomach.
"""
self.connected = True
self._fileno = fd
self.socket = asyncore.file_wrapper(fd)
self.add_channel()
flags = fcntl.fcntl(fd, fcntl.F_GETFL, 0)
flags = flags | os.O_NONBLOCK
fcntl.fcntl(fd, fcntl.F_SETFL, flags)
def handle_close(self):
"""
Exit when channel closed.
"""
asynchat.async_chat.handle_close(self)
sys.exit(0)
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