Reference client for Bitmessage: a P2P encrypted decentralised communication protocol:
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# -*- Mode: Python -*-
# Id: asyncore.py,v 2.51 2000/09/07 22:29:26 rushing Exp
# Author: Sam Rushing <rushing@nightmare.com>
# ======================================================================
# Copyright 1996 by Sam Rushing
#
# All Rights Reserved
#
# Permission to use, copy, modify, and distribute this software and
# its documentation for any purpose and without fee is hereby
# granted, provided that the above copyright notice appear in all
# copies and that both that copyright notice and this permission
# notice appear in supporting documentation, and that the name of Sam
# Rushing not be used in advertising or publicity pertaining to
# distribution of the software without specific, written prior
# permission.
#
# SAM RUSHING DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
# INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
# NO EVENT SHALL SAM RUSHING BE LIABLE FOR ANY SPECIAL, 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.
# ======================================================================
"""Basic infrastructure for asynchronous socket service clients and servers.
There are only two ways to have a program on a single processor do "more
than one thing at a time". Multi-threaded programming is the simplest and
most popular way to do it, but there is another very different technique,
that lets you have nearly all the advantages of multi-threading, without
actually using multiple threads. it's really only practical if your program
is largely I/O bound. If your program is CPU bound, then pre-emptive
scheduled threads are probably what you really need. Network servers are
rarely CPU-bound, however.
If your operating system supports the select() system call in its I/O
library (and nearly all do), then you can use it to juggle multiple
communication channels at once; doing other work while your I/O is taking
place in the "background." Although this strategy can seem strange and
complex, especially at first, it is in many ways easier to understand and
control than multi-threaded programming. The module documented here solves
many of the difficult problems for you, making the task of building
sophisticated high-performance network servers and clients a snap.
"""
# randomise object order for bandwidth balancing
import random
import select
import socket
import sys
import time
import warnings
import os
from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, EINVAL, \
ENOTCONN, ESHUTDOWN, EISCONN, EBADF, ECONNABORTED, EPIPE, EAGAIN, \
ECONNREFUSED, EHOSTUNREACH, \
errorcode
try:
from errno import WSAEWOULDBLOCK
except:
pass
from ssl import SSLError, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE
_DISCONNECTED = frozenset((ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED, EPIPE,
EBADF, ECONNREFUSED, EHOSTUNREACH))
OP_READ = 1
OP_WRITE = 2
try:
socket_map
except NameError:
socket_map = {}
def _strerror(err):
try:
return os.strerror(err)
except (ValueError, OverflowError, NameError):
if err in errorcode:
return errorcode[err]
return "Unknown error %s" %err
class ExitNow(Exception):
pass
_reraised_exceptions = (ExitNow, KeyboardInterrupt, SystemExit)
maxDownloadRate = 0
downloadTimestamp = 0
downloadBucket = 0
receivedBytes = 0
maxUploadRate = 0
uploadTimestamp = 0
uploadBucket = 0
sentBytes = 0
def read(obj):
try:
obj.handle_read_event()
except _reraised_exceptions:
raise
except:
obj.handle_error()
def write(obj):
try:
obj.handle_write_event()
except _reraised_exceptions:
raise
except:
obj.handle_error()
def set_rates(download, upload):
global maxDownloadRate, maxUploadRate, downloadBucket, uploadBucket, downloadTimestamp, uploadTimestamp
maxDownloadRate = float(download)
maxUploadRate = float(upload)
downloadBucket = maxDownloadRate
uploadBucket = maxUploadRate
downloadTimestamp = time.time()
uploadTimestamp = time.time()
def update_received(download=0):
global receivedBytes, maxDownloadRate, downloadBucket, downloadTimestamp
currentTimestamp = time.time()
receivedBytes += download
if maxDownloadRate > 0:
bucketIncrease = int(maxDownloadRate * (currentTimestamp - downloadTimestamp))
downloadBucket += bucketIncrease
if downloadBucket > maxDownloadRate:
downloadBucket = int(maxDownloadRate)
downloadBucket -= download
downloadTimestamp = currentTimestamp
def update_sent(upload=0):
global sentBytes, maxUploadRate, uploadBucket, uploadTimestamp
currentTimestamp = time.time()
sentBytes += upload
if maxUploadRate > 0:
bucketIncrease = int(maxUploadRate * (currentTimestamp - uploadTimestamp))
uploadBucket += bucketIncrease
if uploadBucket > maxUploadRate:
uploadBucket = int(maxUploadRate)
uploadBucket -= upload
uploadTimestamp = currentTimestamp
def _exception(obj):
try:
obj.handle_expt_event()
except _reraised_exceptions:
raise
except:
obj.handle_error()
def readwrite(obj, flags):
try:
if flags & select.POLLIN:
obj.handle_read_event()
if flags & select.POLLOUT:
obj.handle_write_event()
if flags & select.POLLPRI:
obj.handle_expt_event()
if flags & (select.POLLHUP | select.POLLERR | select.POLLNVAL):
obj.handle_close()
except socket.error as e:
if e.args[0] not in _DISCONNECTED:
obj.handle_error()
else:
obj.handle_close()
except _reraised_exceptions:
raise
except:
obj.handle_error()
def select_poller(timeout=0.0, map=None):
"""A poller which uses select(), available on most platforms."""
if map is None:
map = socket_map
if map:
r = []; w = []; e = []
for fd, obj in list(map.items()):
is_r = obj.readable()
is_w = obj.writable()
if is_r:
r.append(fd)
# accepting sockets should not be writable
if is_w and not obj.accepting:
w.append(fd)
if is_r or is_w:
e.append(fd)
if [] == r == w == e:
time.sleep(timeout)
return
try:
r, w, e = select.select(r, w, e, timeout)
except KeyboardInterrupt:
return
for fd in random.sample(r, len(r)):
obj = map.get(fd)
if obj is None:
continue
read(obj)
for fd in random.sample(w, len(w)):
obj = map.get(fd)
if obj is None:
continue
write(obj)
for fd in e:
obj = map.get(fd)
if obj is None:
continue
_exception(obj)
def poll_poller(timeout=0.0, map=None):
"""A poller which uses poll(), available on most UNIXen."""
if map is None:
map = socket_map
if timeout is not None:
# timeout is in milliseconds
timeout = int(timeout*1000)
try:
poll_poller.pollster
except AttributeError:
poll_poller.pollster = select.poll()
if map:
for fd, obj in list(map.items()):
flags = newflags = 0
if obj.readable():
flags |= select.POLLIN | select.POLLPRI
newflags |= OP_READ
else:
newflags &= ~ OP_READ
# accepting sockets should not be writable
if obj.writable() and not obj.accepting:
flags |= select.POLLOUT
newflags |= OP_WRITE
else:
newflags &= ~ OP_WRITE
if newflags != obj.flags:
obj.flags = newflags
if obj.poller_registered:
poll_poller.pollster.modify(fd, flags)
else:
poll_poller.pollster.register(fd, flags)
obj.poller_registered = True
try:
r = poll_poller.pollster.poll(timeout)
except KeyboardInterrupt:
r = []
for fd, flags in random.sample(r, len(r)):
obj = map.get(fd)
if obj is None:
continue
readwrite(obj, flags)
# Aliases for backward compatibility
poll = select_poller
poll2 = poll3 = poll_poller
def epoll_poller(timeout=0.0, map=None):
"""A poller which uses epoll(), supported on Linux 2.5.44 and newer."""
if map is None:
map = socket_map
try:
epoll_poller.pollster
except AttributeError:
epoll_poller.pollster = select.epoll()
if map:
for fd, obj in map.items():
flags = newflags = 0
if obj.readable():
flags |= select.POLLIN | select.POLLPRI
newflags |= OP_READ
else:
newflags &= ~ OP_READ
# accepting sockets should not be writable
if obj.writable() and not obj.accepting:
flags |= select.POLLOUT
newflags |= OP_WRITE
else:
newflags &= ~ OP_WRITE
if newflags != obj.flags:
obj.flags = newflags
# Only check for exceptions if object was either readable
# or writable.
flags |= select.POLLERR | select.POLLHUP | select.POLLNVAL
if obj.poller_registered:
epoll_poller.pollster.modify(fd, flags)
else:
epoll_poller.pollster.register(fd, flags)
obj.poller_registered = True
try:
r = epoll_poller.pollster.poll(timeout)
except select.error, err:
if err.args[0] != EINTR:
raise
r = []
for fd, flags in random.sample(r, len(r)):
obj = map.get(fd)
if obj is None:
continue
readwrite(obj, flags)
def kqueue_poller(timeout=0.0, map=None):
"""A poller which uses kqueue(), BSD specific."""
if map is None:
map = socket_map
if map:
kqueue = select.kqueue()
flags = select.KQ_EV_ADD | select.KQ_EV_ENABLE
selectables = 0
for fd, obj in map.items():
filter = 0
if obj.readable():
filter |= select.KQ_FILTER_READ
if obj.writable():
filter |= select.KQ_FILTER_WRITE
if filter:
ev = select.kevent(fd, filter=filter, flags=flags)
kqueue.control([ev], 0)
selectables += 1
events = kqueue.control(None, selectables, timeout)
for event in random.sample(events, len(events)):
fd = event.ident
obj = map.get(fd)
if obj is None:
continue
if event.filter == select.KQ_FILTER_READ:
read(obj)
if event.filter == select.KQ_FILTER_WRITE:
write(obj)
kqueue.close()
def loop(timeout=30.0, use_poll=False, map=None, count=None,
poller=select_poller):
if map is None:
map = socket_map
# code which grants backward compatibility with "use_poll"
# argument which should no longer be used in favor of
# "poller"
if hasattr(select, 'epoll'):
poller = epoll_poller
elif hasattr(select, 'kqueue'):
poller = kqueue_poller
elif hasattr(select, 'poll'):
poller = poll_poller
elif hasattr(select, 'select'):
poller = select_poller
poller = select_poller
# print "Poll loop using %s" % (poller.__name__)
if count is None:
while map:
# fill buckets first
update_sent()
update_received()
# then poll
poller(timeout, map)
else:
timeout /= count
while map and count > 0:
# fill buckets first
update_sent()
update_received()
poller(timeout, map)
# then poll
count = count - 1
class dispatcher:
debug = False
connected = False
accepting = False
connecting = False
closing = False
addr = None
ignore_log_types = frozenset(['warning'])
poller_registered = False
flags = 0
# don't do network IO with a smaller bucket than this
minTx = 1500
def __init__(self, sock=None, map=None):
if map is None:
self._map = socket_map
else:
self._map = map
self._fileno = None
if sock:
# Set to nonblocking just to make sure for cases where we
# get a socket from a blocking source.
sock.setblocking(0)
self.set_socket(sock, map)
self.connected = True
# The constructor no longer requires that the socket
# passed be connected.
try:
self.addr = sock.getpeername()
except socket.error as err:
if err.args[0] in (ENOTCONN, EINVAL):
# To handle the case where we got an unconnected
# socket.
self.connected = False
else:
# The socket is broken in some unknown way, alert
# the user and remove it from the map (to prevent
# polling of broken sockets).
self.del_channel(map)
raise
else:
self.socket = None
def __repr__(self):
status = [self.__class__.__module__+"."+self.__class__.__name__]
if self.accepting and self.addr:
status.append('listening')
elif self.connected:
status.append('connected')
if self.addr is not None:
try:
status.append('%s:%d' % self.addr)
except TypeError:
status.append(repr(self.addr))
return '<%s at %#x>' % (' '.join(status), id(self))
__str__ = __repr__
def add_channel(self, map=None):
#self.log_info('adding channel %s' % self)
if map is None:
map = self._map
map[self._fileno] = self
def del_channel(self, map=None):
fd = self._fileno
if map is None:
map = self._map
if fd in map:
#self.log_info('closing channel %d:%s' % (fd, self))
del map[fd]
self._fileno = None
try:
epoll_poller.pollster.unregister(fd)
except (AttributeError, KeyError, TypeError):
# no epoll used, or not registered
pass
try:
poll_poller.pollster.unregister(fd)
except (AttributeError, KeyError, TypeError):
# no poll used, or not registered
pass
def create_socket(self, family=socket.AF_INET, type=socket.SOCK_STREAM):
self.family_and_type = family, type
sock = socket.socket(family, type)
sock.setblocking(0)
self.set_socket(sock)
def set_socket(self, sock, map=None):
self.socket = sock
## self.__dict__['socket'] = sock
self._fileno = sock.fileno()
self.add_channel(map)
def set_reuse_addr(self):
# try to re-use a server port if possible
try:
self.socket.setsockopt(
socket.SOL_SOCKET, socket.SO_REUSEADDR,
self.socket.getsockopt(socket.SOL_SOCKET,
socket.SO_REUSEADDR) | 1
)
except socket.error:
pass
# ==================================================
# predicates for select()
# these are used as filters for the lists of sockets
# to pass to select().
# ==================================================
def readable(self):
if maxDownloadRate > 0:
return downloadBucket > dispatcher.minTx
return True
def writable(self):
if maxUploadRate > 0:
return uploadBucket > dispatcher.minTx
return True
# ==================================================
# socket object methods.
# ==================================================
def listen(self, num):
self.accepting = True
if os.name == 'nt' and num > 5:
num = 5
return self.socket.listen(num)
def bind(self, addr):
self.addr = addr
return self.socket.bind(addr)
def connect(self, address):
self.connected = False
self.connecting = True
err = self.socket.connect_ex(address)
if err in (EINPROGRESS, EALREADY, EWOULDBLOCK) \
or err == EINVAL and os.name in ('nt', 'ce'):
self.addr = address
return
if err in (0, EISCONN):
self.addr = address
self.handle_connect_event()
else:
raise socket.error(err, errorcode[err])
def accept(self):
# XXX can return either an address pair or None
try:
conn, addr = self.socket.accept()
except TypeError:
return None
except socket.error as why:
if why.args[0] in (EWOULDBLOCK, ECONNABORTED, EAGAIN, ENOTCONN):
return None
else:
raise
else:
return conn, addr
def send(self, data):
try:
result = self.socket.send(data)
return result
except SSLError as err:
if err.errno == SSL_ERROR_WANT_WRITE:
return 0
else:
raise
except socket.error as why:
if why.args[0] in (EAGAIN, EWOULDBLOCK) or \
(sys.platform.startswith('win') and \
err.errno == WSAEWOULDBLOCK):
return 0
elif why.args[0] in _DISCONNECTED:
self.handle_close()
return 0
else:
raise
def recv(self, buffer_size):
try:
data = self.socket.recv(buffer_size)
if not data:
# a closed connection is indicated by signaling
# a read condition, and having recv() return 0.
self.handle_close()
return b''
else:
return data
except SSLError as err:
if err.errno == SSL_ERROR_WANT_READ:
return b''
else:
raise
except socket.error as why:
# winsock sometimes raises ENOTCONN
if why.args[0] in (EAGAIN, EWOULDBLOCK) or \
(sys.platform.startswith('win') and \
err.errno == WSAEWOULDBLOCK):
return b''
if why.args[0] in _DISCONNECTED:
self.handle_close()
return b''
else:
raise
def close(self):
self.connected = False
self.accepting = False
self.connecting = False
self.del_channel()
try:
self.socket.close()
except socket.error as why:
if why.args[0] not in (ENOTCONN, EBADF):
raise
# cheap inheritance, used to pass all other attribute
# references to the underlying socket object.
def __getattr__(self, attr):
try:
retattr = getattr(self.socket, attr)
except AttributeError:
raise AttributeError("%s instance has no attribute '%s'"
%(self.__class__.__name__, attr))
else:
msg = "%(me)s.%(attr)s is deprecated; use %(me)s.socket.%(attr)s " \
"instead" % {'me' : self.__class__.__name__, 'attr' : attr}
warnings.warn(msg, DeprecationWarning, stacklevel=2)
return retattr
# log and log_info may be overridden to provide more sophisticated
# logging and warning methods. In general, log is for 'hit' logging
# and 'log_info' is for informational, warning and error logging.
def log(self, message):
sys.stderr.write('log: %s\n' % str(message))
def log_info(self, message, type='info'):
if type not in self.ignore_log_types:
print('%s: %s' % (type, message))
def handle_read_event(self):
if self.accepting:
# accepting sockets are never connected, they "spawn" new
# sockets that are connected
self.handle_accept()
elif not self.connected:
if self.connecting:
self.handle_connect_event()
self.handle_read()
else:
self.handle_read()
def handle_connect_event(self):
err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
if err != 0:
raise socket.error(err, _strerror(err))
self.handle_connect()
self.connected = True
self.connecting = False
def handle_write_event(self):
if self.accepting:
# Accepting sockets shouldn't get a write event.
# We will pretend it didn't happen.
return
if not self.connected:
if self.connecting:
self.handle_connect_event()
self.handle_write()
def handle_expt_event(self):
# handle_expt_event() is called if there might be an error on the
# socket, or if there is OOB data
# check for the error condition first
err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
if err != 0:
# we can get here when select.select() says that there is an
# exceptional condition on the socket
# since there is an error, we'll go ahead and close the socket
# like we would in a subclassed handle_read() that received no
# data
self.handle_close()
else:
self.handle_expt()
def handle_error(self):
nil, t, v, tbinfo = compact_traceback()
# sometimes a user repr method will crash.
try:
self_repr = repr(self)
except:
self_repr = '<__repr__(self) failed for object at %0x>' % id(self)
self.log_info(
'uncaptured python exception, closing channel %s (%s:%s %s)' % (
self_repr,
t,
v,
tbinfo
),
'error'
)
self.handle_close()
def handle_expt(self):
self.log_info('unhandled incoming priority event', 'warning')
def handle_read(self):
self.log_info('unhandled read event', 'warning')
def handle_write(self):
self.log_info('unhandled write event', 'warning')
def handle_connect(self):
self.log_info('unhandled connect event', 'warning')
def handle_accept(self):
pair = self.accept()
if pair is not None:
self.handle_accepted(*pair)
def handle_accepted(self, sock, addr):
sock.close()
self.log_info('unhandled accepted event', 'warning')
def handle_close(self):
self.log_info('unhandled close event', 'warning')
self.close()
# ---------------------------------------------------------------------------
# adds simple buffered output capability, useful for simple clients.
# [for more sophisticated usage use asynchat.async_chat]
# ---------------------------------------------------------------------------
class dispatcher_with_send(dispatcher):
def __init__(self, sock=None, map=None):
dispatcher.__init__(self, sock, map)
self.out_buffer = b''
def initiate_send(self):
num_sent = 0
num_sent = dispatcher.send(self, self.out_buffer[:512])
self.out_buffer = self.out_buffer[num_sent:]
def handle_write(self):
self.initiate_send()
def writable(self):
return (not self.connected) or len(self.out_buffer)
def send(self, data):
if self.debug:
self.log_info('sending %s' % repr(data))
self.out_buffer = self.out_buffer + data
self.initiate_send()
# ---------------------------------------------------------------------------
# used for debugging.
# ---------------------------------------------------------------------------
def compact_traceback():
t, v, tb = sys.exc_info()
tbinfo = []
if not tb: # Must have a traceback
raise AssertionError("traceback does not exist")
while tb:
tbinfo.append((
tb.tb_frame.f_code.co_filename,
tb.tb_frame.f_code.co_name,
str(tb.tb_lineno)
))
tb = tb.tb_next
# just to be safe
del tb
file, function, line = tbinfo[-1]
info = ' '.join(['[%s|%s|%s]' % x for x in tbinfo])
return (file, function, line), t, v, info
def close_all(map=None, ignore_all=False):
if map is None:
map = socket_map
for x in list(map.values()):
try:
x.close()
except OSError as x:
if x.args[0] == EBADF:
pass
elif not ignore_all:
raise
except _reraised_exceptions:
raise
except:
if not ignore_all:
raise
map.clear()
# Asynchronous File I/O:
#
# After a little research (reading man pages on various unixen, and
# digging through the linux kernel), I've determined that select()
# isn't meant for doing asynchronous file i/o.
# Heartening, though - reading linux/mm/filemap.c shows that linux
# supports asynchronous read-ahead. So _MOST_ of the time, the data
# will be sitting in memory for us already when we go to read it.
#
# What other OS's (besides NT) support async file i/o? [VMS?]
#
# Regardless, this is useful for pipes, and stdin/stdout...
if os.name == 'posix':
import fcntl
class file_wrapper:
# Here we override just enough to make a file
# look like a socket for the purposes of asyncore.
# The passed fd is automatically os.dup()'d
def __init__(self, fd):
self.fd = os.dup(fd)
def recv(self, *args):
return os.read(self.fd, *args)
def send(self, *args):
return os.write(self.fd, *args)
def getsockopt(self, level, optname, buflen=None):
if (level == socket.SOL_SOCKET and
optname == socket.SO_ERROR and
not buflen):
return 0
raise NotImplementedError("Only asyncore specific behaviour "
"implemented.")
read = recv
write = send
def close(self):
os.close(self.fd)
def fileno(self):
return self.fd
class file_dispatcher(dispatcher):
def __init__(self, fd, map=None):
dispatcher.__init__(self, None, map)
self.connected = True
try:
fd = fd.fileno()
except AttributeError:
pass
self.set_file(fd)
# set it to non-blocking mode
flags = fcntl.fcntl(fd, fcntl.F_GETFL, 0)
flags = flags | os.O_NONBLOCK
fcntl.fcntl(fd, fcntl.F_SETFL, flags)
def set_file(self, fd):
self.socket = file_wrapper(fd)
self._fileno = self.socket.fileno()
self.add_channel()