# Copyright (c) 2009-2012 Denis Bilenko. See LICENSE for details.
"""TCP/SSL server"""
from __future__ import print_function
from __future__ import absolute_import
from __future__ import division
import sys
from _socket import error as SocketError
from _socket import SOL_SOCKET
from _socket import SO_REUSEADDR
from _socket import AF_INET
from _socket import SOCK_DGRAM
from gevent.baseserver import BaseServer
from gevent.socket import EWOULDBLOCK
from gevent.socket import socket as GeventSocket
__all__ = ['StreamServer', 'DatagramServer']
if sys.platform == 'win32':
# SO_REUSEADDR on Windows does not mean the same thing as on *nix (issue #217)
DEFAULT_REUSE_ADDR = None
else:
DEFAULT_REUSE_ADDR = 1
# sockets and SSL sockets are context managers on Python 3
def _closing_socket(sock):
return sock
[docs]
class StreamServer(BaseServer):
"""
A generic TCP server.
Accepts connections on a listening socket and spawns user-provided
*handle* function for each connection with 2 arguments: the client
socket and the client address.
Note that although the errors in a successfully spawned handler
will not affect the server or other connections, the errors raised
by :func:`accept` and *spawn* cause the server to stop accepting
for a short amount of time. The exact period depends on the values
of :attr:`min_delay` and :attr:`max_delay` attributes.
The delay starts with :attr:`min_delay` and doubles with each
successive error until it reaches :attr:`max_delay`. A successful
:func:`accept` resets the delay to :attr:`min_delay` again.
See :class:`~gevent.baseserver.BaseServer` for information on defining the *handle*
function and important restrictions on it.
**SSL Support**
The server can optionally work in SSL mode when given the correct
keyword arguments. (That is, the presence of any keyword arguments
will trigger SSL mode.) On Python 2.7.9 and later (any Python
version that supports the :class:`ssl.SSLContext`), this can be
done with a configured ``SSLContext``. On any Python version, it
can be done by passing the appropriate arguments for
:func:`ssl.wrap_socket`.
The incoming socket will be wrapped into an SSL socket before
being passed to the *handle* function.
If the *ssl_context* keyword argument is present, it should
contain an :class:`ssl.SSLContext`. The remaining keyword
arguments are passed to the :meth:`ssl.SSLContext.wrap_socket`
method of that object. Depending on the Python version, supported arguments
may include:
- server_hostname
- suppress_ragged_eofs
- do_handshake_on_connect
.. caution:: When using an SSLContext, it should either be
imported from :mod:`gevent.ssl`, or the process needs to be monkey-patched.
If the process is not monkey-patched and you pass the standard library
SSLContext, the resulting client sockets will not cooperate with gevent.
Otherwise, keyword arguments are assumed to apply to :func:`ssl.wrap_socket`.
These keyword arguments may include:
- keyfile
- certfile
- cert_reqs
- ssl_version
- ca_certs
- suppress_ragged_eofs
- do_handshake_on_connect
- ciphers
.. versionchanged:: 1.2a2
Add support for the *ssl_context* keyword argument.
"""
# the default backlog to use if none was provided in __init__
# For TCP, 128 is the (default) maximum at the operating system level on Linux and macOS
# larger values are truncated to 128.
#
# Windows defines SOMAXCONN=0x7fffffff to mean "max reasonable value" --- that value
# was undocumented and subject to change, but appears to be 200.
# Beginning in Windows 8 there's SOMAXCONN_HINT(b)=(-(b)) which means "at least
# as many SOMAXCONN but no more than b" which is a portable way to write 200.
backlog = 128
reuse_addr = DEFAULT_REUSE_ADDR
def __init__(self, listener, handle=None, backlog=None, spawn='default', **ssl_args):
BaseServer.__init__(self, listener, handle=handle, spawn=spawn)
try:
if ssl_args:
ssl_args.setdefault('server_side', True)
if 'ssl_context' in ssl_args:
ssl_context = ssl_args.pop('ssl_context')
self.wrap_socket = ssl_context.wrap_socket
self.ssl_args = ssl_args
else:
from gevent.ssl import wrap_socket
self.wrap_socket = wrap_socket
self.ssl_args = ssl_args
else:
self.ssl_args = None
if backlog is not None:
if hasattr(self, 'socket'):
raise TypeError('backlog must be None when a socket instance is passed')
self.backlog = backlog
except:
self.close()
raise
@property
def ssl_enabled(self):
return self.ssl_args is not None
def set_listener(self, listener):
BaseServer.set_listener(self, listener)
def _make_socket_stdlib(self, fresh):
# We want to unwrap the gevent wrapping of the listening socket.
# This lets us be just a hair more efficient: when our 'do_read' is
# called, we've already waited on the socket to be ready to accept(), so
# we don't need to (potentially) do it again. Also we avoid a layer
# of method calls. The cost, though, is that we have to manually wrap
# sockets back up to be non-blocking in do_read(). I'm not sure that's worth
# it.
#
# In the past, we only did this when set_listener() was called with a socket
# object and not an address. It makes sense to do it always though,
# so that we get consistent behaviour.
while hasattr(self.socket, '_sock'):
if fresh:
if hasattr(self.socket, '_drop_events'):
# Discard event listeners. This socket object is not shared,
# so we don't need them anywhere else.
# This matters somewhat for libuv, where we have to multiplex
# listeners, and we're about to create a new listener.
# If we don't do this, on Windows libuv tends to miss incoming
# connects and our _do_read callback doesn't get called.
self.socket._drop_events()
# XXX: Do we need to _drop() for PyPy?
self.socket = self.socket._sock # pylint:disable=attribute-defined-outside-init
[docs]
def init_socket(self):
fresh = False
if not hasattr(self, 'socket'):
fresh = True
# FIXME: clean up the socket lifetime
# pylint:disable=attribute-defined-outside-init
self.socket = self.get_listener(self.address, self.backlog, self.family)
self.address = self.socket.getsockname()
if self.ssl_args:
self._handle = self.wrap_socket_and_handle
else:
self._handle = self.handle
self._make_socket_stdlib(fresh)
@classmethod
def get_listener(cls, address, backlog=None, family=None):
if backlog is None:
backlog = cls.backlog
return _tcp_listener(address, backlog=backlog, reuse_addr=cls.reuse_addr, family=family)
def do_read(self):
sock = self.socket
try:
fd, address = sock._accept()
except BlockingIOError: # python 2: pylint: disable=undefined-variable
if not sock.timeout:
return
raise
sock = GeventSocket(sock.family, sock.type, sock.proto, fileno=fd)
# XXX Python issue #7995? "if no default timeout is set
# and the listening socket had a (non-zero) timeout, force
# the new socket in blocking mode to override
# platform-specific socket flags inheritance."
return sock, address
def do_close(self, sock, *args):
# pylint:disable=arguments-differ
sock.close()
def wrap_socket_and_handle(self, client_socket, address):
# used in case of ssl sockets
with _closing_socket(self.wrap_socket(client_socket, **self.ssl_args)) as ssl_socket:
return self.handle(ssl_socket, address)
[docs]
class DatagramServer(BaseServer):
"""A UDP server"""
reuse_addr = DEFAULT_REUSE_ADDR
def __init__(self, *args, **kwargs):
# The raw (non-gevent) socket, if possible
self._socket = None
BaseServer.__init__(self, *args, **kwargs)
from gevent.lock import Semaphore
self._writelock = Semaphore()
[docs]
def init_socket(self):
if not hasattr(self, 'socket'):
# FIXME: clean up the socket lifetime
# pylint:disable=attribute-defined-outside-init
self.socket = self.get_listener(self.address, self.family)
self.address = self.socket.getsockname()
self._socket = self.socket
try:
self._socket = self._socket._sock
except AttributeError:
pass
@classmethod
def get_listener(cls, address, family=None):
return _udp_socket(address, reuse_addr=cls.reuse_addr, family=family)
def do_read(self):
try:
data, address = self._socket.recvfrom(8192)
except SocketError as err:
if err.args[0] == EWOULDBLOCK:
return
raise
return data, address
def sendto(self, *args):
self._writelock.acquire()
try:
self.socket.sendto(*args)
finally:
self._writelock.release()
def _tcp_listener(address, backlog=50, reuse_addr=None, family=AF_INET):
"""A shortcut to create a TCP socket, bind it and put it into listening state."""
sock = GeventSocket(family=family)
if reuse_addr is not None:
sock.setsockopt(SOL_SOCKET, SO_REUSEADDR, reuse_addr)
try:
sock.bind(address)
except SocketError as ex:
strerror = getattr(ex, 'strerror', None)
if strerror is not None:
ex.strerror = strerror + ': ' + repr(address)
raise
sock.listen(backlog)
sock.setblocking(0)
return sock
def _udp_socket(address, backlog=50, reuse_addr=None, family=AF_INET):
# backlog argument for compat with tcp_listener
# pylint:disable=unused-argument
# we want gevent.socket.socket here
sock = GeventSocket(family=family, type=SOCK_DGRAM)
if reuse_addr is not None:
sock.setsockopt(SOL_SOCKET, SO_REUSEADDR, reuse_addr)
try:
sock.bind(address)
except SocketError as ex:
strerror = getattr(ex, 'strerror', None)
if strerror is not None:
ex.strerror = strerror + ': ' + repr(address)
raise
return sock