kopia lustrzana https://github.com/micropython/micropython
746 wiersze
24 KiB
Python
746 wiersze
24 KiB
Python
![]() |
"""Generic socket server classes.
|
||
|
|
||
|
This module tries to capture the various aspects of defining a server:
|
||
|
|
||
|
For socket-based servers:
|
||
|
|
||
|
- address family:
|
||
|
- AF_INET{,6}: IP (Internet Protocol) sockets (default)
|
||
|
- AF_UNIX: Unix domain sockets
|
||
|
- others, e.g. AF_DECNET are conceivable (see <socket.h>
|
||
|
- socket type:
|
||
|
- SOCK_STREAM (reliable stream, e.g. TCP)
|
||
|
- SOCK_DGRAM (datagrams, e.g. UDP)
|
||
|
|
||
|
For request-based servers (including socket-based):
|
||
|
|
||
|
- client address verification before further looking at the request
|
||
|
(This is actually a hook for any processing that needs to look
|
||
|
at the request before anything else, e.g. logging)
|
||
|
- how to handle multiple requests:
|
||
|
- synchronous (one request is handled at a time)
|
||
|
- forking (each request is handled by a new process)
|
||
|
- threading (each request is handled by a new thread)
|
||
|
|
||
|
The classes in this module favor the server type that is simplest to
|
||
|
write: a synchronous TCP/IP server. This is bad class design, but
|
||
|
save some typing. (There's also the issue that a deep class hierarchy
|
||
|
slows down method lookups.)
|
||
|
|
||
|
There are five classes in an inheritance diagram, four of which represent
|
||
|
synchronous servers of four types:
|
||
|
|
||
|
+------------+
|
||
|
| BaseServer |
|
||
|
+------------+
|
||
|
|
|
||
|
v
|
||
|
+-----------+ +------------------+
|
||
|
| TCPServer |------->| UnixStreamServer |
|
||
|
+-----------+ +------------------+
|
||
|
|
|
||
|
v
|
||
|
+-----------+ +--------------------+
|
||
|
| UDPServer |------->| UnixDatagramServer |
|
||
|
+-----------+ +--------------------+
|
||
|
|
||
|
Note that UnixDatagramServer derives from UDPServer, not from
|
||
|
UnixStreamServer -- the only difference between an IP and a Unix
|
||
|
stream server is the address family, which is simply repeated in both
|
||
|
unix server classes.
|
||
|
|
||
|
Forking and threading versions of each type of server can be created
|
||
|
using the ForkingMixIn and ThreadingMixIn mix-in classes. For
|
||
|
instance, a threading UDP server class is created as follows:
|
||
|
|
||
|
class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass
|
||
|
|
||
|
The Mix-in class must come first, since it overrides a method defined
|
||
|
in UDPServer! Setting the various member variables also changes
|
||
|
the behavior of the underlying server mechanism.
|
||
|
|
||
|
To implement a service, you must derive a class from
|
||
|
BaseRequestHandler and redefine its handle() method. You can then run
|
||
|
various versions of the service by combining one of the server classes
|
||
|
with your request handler class.
|
||
|
|
||
|
The request handler class must be different for datagram or stream
|
||
|
services. This can be hidden by using the request handler
|
||
|
subclasses StreamRequestHandler or DatagramRequestHandler.
|
||
|
|
||
|
Of course, you still have to use your head!
|
||
|
|
||
|
For instance, it makes no sense to use a forking server if the service
|
||
|
contains state in memory that can be modified by requests (since the
|
||
|
modifications in the child process would never reach the initial state
|
||
|
kept in the parent process and passed to each child). In this case,
|
||
|
you can use a threading server, but you will probably have to use
|
||
|
locks to avoid two requests that come in nearly simultaneous to apply
|
||
|
conflicting changes to the server state.
|
||
|
|
||
|
On the other hand, if you are building e.g. an HTTP server, where all
|
||
|
data is stored externally (e.g. in the file system), a synchronous
|
||
|
class will essentially render the service "deaf" while one request is
|
||
|
being handled -- which may be for a very long time if a client is slow
|
||
|
to read all the data it has requested. Here a threading or forking
|
||
|
server is appropriate.
|
||
|
|
||
|
In some cases, it may be appropriate to process part of a request
|
||
|
synchronously, but to finish processing in a forked child depending on
|
||
|
the request data. This can be implemented by using a synchronous
|
||
|
server and doing an explicit fork in the request handler class
|
||
|
handle() method.
|
||
|
|
||
|
Another approach to handling multiple simultaneous requests in an
|
||
|
environment that supports neither threads nor fork (or where these are
|
||
|
too expensive or inappropriate for the service) is to maintain an
|
||
|
explicit table of partially finished requests and to use select() to
|
||
|
decide which request to work on next (or whether to handle a new
|
||
|
incoming request). This is particularly important for stream services
|
||
|
where each client can potentially be connected for a long time (if
|
||
|
threads or subprocesses cannot be used).
|
||
|
|
||
|
Future work:
|
||
|
- Standard classes for Sun RPC (which uses either UDP or TCP)
|
||
|
- Standard mix-in classes to implement various authentication
|
||
|
and encryption schemes
|
||
|
- Standard framework for select-based multiplexing
|
||
|
|
||
|
XXX Open problems:
|
||
|
- What to do with out-of-band data?
|
||
|
|
||
|
BaseServer:
|
||
|
- split generic "request" functionality out into BaseServer class.
|
||
|
Copyright (C) 2000 Luke Kenneth Casson Leighton <lkcl@samba.org>
|
||
|
|
||
|
example: read entries from a SQL database (requires overriding
|
||
|
get_request() to return a table entry from the database).
|
||
|
entry is processed by a RequestHandlerClass.
|
||
|
|
||
|
"""
|
||
|
|
||
|
# Author of the BaseServer patch: Luke Kenneth Casson Leighton
|
||
|
|
||
|
# XXX Warning!
|
||
|
# There is a test suite for this module, but it cannot be run by the
|
||
|
# standard regression test.
|
||
|
# To run it manually, run Lib/test/test_socketserver.py.
|
||
|
|
||
|
__version__ = "0.4"
|
||
|
|
||
|
|
||
|
import socket
|
||
|
import select
|
||
|
import sys
|
||
|
import os
|
||
|
import errno
|
||
|
try:
|
||
|
import threading
|
||
|
except ImportError:
|
||
|
import dummy_threading as threading
|
||
|
|
||
|
__all__ = ["TCPServer","UDPServer","ForkingUDPServer","ForkingTCPServer",
|
||
|
"ThreadingUDPServer","ThreadingTCPServer","BaseRequestHandler",
|
||
|
"StreamRequestHandler","DatagramRequestHandler",
|
||
|
"ThreadingMixIn", "ForkingMixIn"]
|
||
|
if hasattr(socket, "AF_UNIX"):
|
||
|
__all__.extend(["UnixStreamServer","UnixDatagramServer",
|
||
|
"ThreadingUnixStreamServer",
|
||
|
"ThreadingUnixDatagramServer"])
|
||
|
|
||
|
def _eintr_retry(func, *args):
|
||
|
"""restart a system call interrupted by EINTR"""
|
||
|
while True:
|
||
|
try:
|
||
|
return func(*args)
|
||
|
except OSError as e:
|
||
|
if e.errno != errno.EINTR:
|
||
|
raise
|
||
|
|
||
|
class BaseServer:
|
||
|
|
||
|
"""Base class for server classes.
|
||
|
|
||
|
Methods for the caller:
|
||
|
|
||
|
- __init__(server_address, RequestHandlerClass)
|
||
|
- serve_forever(poll_interval=0.5)
|
||
|
- shutdown()
|
||
|
- handle_request() # if you do not use serve_forever()
|
||
|
- fileno() -> int # for select()
|
||
|
|
||
|
Methods that may be overridden:
|
||
|
|
||
|
- server_bind()
|
||
|
- server_activate()
|
||
|
- get_request() -> request, client_address
|
||
|
- handle_timeout()
|
||
|
- verify_request(request, client_address)
|
||
|
- server_close()
|
||
|
- process_request(request, client_address)
|
||
|
- shutdown_request(request)
|
||
|
- close_request(request)
|
||
|
- service_actions()
|
||
|
- handle_error()
|
||
|
|
||
|
Methods for derived classes:
|
||
|
|
||
|
- finish_request(request, client_address)
|
||
|
|
||
|
Class variables that may be overridden by derived classes or
|
||
|
instances:
|
||
|
|
||
|
- timeout
|
||
|
- address_family
|
||
|
- socket_type
|
||
|
- allow_reuse_address
|
||
|
|
||
|
Instance variables:
|
||
|
|
||
|
- RequestHandlerClass
|
||
|
- socket
|
||
|
|
||
|
"""
|
||
|
|
||
|
timeout = None
|
||
|
|
||
|
def __init__(self, server_address, RequestHandlerClass):
|
||
|
"""Constructor. May be extended, do not override."""
|
||
|
self.server_address = server_address
|
||
|
self.RequestHandlerClass = RequestHandlerClass
|
||
|
self.__is_shut_down = threading.Event()
|
||
|
self.__shutdown_request = False
|
||
|
|
||
|
def server_activate(self):
|
||
|
"""Called by constructor to activate the server.
|
||
|
|
||
|
May be overridden.
|
||
|
|
||
|
"""
|
||
|
pass
|
||
|
|
||
|
def serve_forever(self, poll_interval=0.5):
|
||
|
"""Handle one request at a time until shutdown.
|
||
|
|
||
|
Polls for shutdown every poll_interval seconds. Ignores
|
||
|
self.timeout. If you need to do periodic tasks, do them in
|
||
|
another thread.
|
||
|
"""
|
||
|
self.__is_shut_down.clear()
|
||
|
try:
|
||
|
while not self.__shutdown_request:
|
||
|
# XXX: Consider using another file descriptor or
|
||
|
# connecting to the socket to wake this up instead of
|
||
|
# polling. Polling reduces our responsiveness to a
|
||
|
# shutdown request and wastes cpu at all other times.
|
||
|
r, w, e = _eintr_retry(select.select, [self], [], [],
|
||
|
poll_interval)
|
||
|
if self in r:
|
||
|
self._handle_request_noblock()
|
||
|
|
||
|
self.service_actions()
|
||
|
finally:
|
||
|
self.__shutdown_request = False
|
||
|
self.__is_shut_down.set()
|
||
|
|
||
|
def shutdown(self):
|
||
|
"""Stops the serve_forever loop.
|
||
|
|
||
|
Blocks until the loop has finished. This must be called while
|
||
|
serve_forever() is running in another thread, or it will
|
||
|
deadlock.
|
||
|
"""
|
||
|
self.__shutdown_request = True
|
||
|
self.__is_shut_down.wait()
|
||
|
|
||
|
def service_actions(self):
|
||
|
"""Called by the serve_forever() loop.
|
||
|
|
||
|
May be overridden by a subclass / Mixin to implement any code that
|
||
|
needs to be run during the loop.
|
||
|
"""
|
||
|
pass
|
||
|
|
||
|
# The distinction between handling, getting, processing and
|
||
|
# finishing a request is fairly arbitrary. Remember:
|
||
|
#
|
||
|
# - handle_request() is the top-level call. It calls
|
||
|
# select, get_request(), verify_request() and process_request()
|
||
|
# - get_request() is different for stream or datagram sockets
|
||
|
# - process_request() is the place that may fork a new process
|
||
|
# or create a new thread to finish the request
|
||
|
# - finish_request() instantiates the request handler class;
|
||
|
# this constructor will handle the request all by itself
|
||
|
|
||
|
def handle_request(self):
|
||
|
"""Handle one request, possibly blocking.
|
||
|
|
||
|
Respects self.timeout.
|
||
|
"""
|
||
|
# Support people who used socket.settimeout() to escape
|
||
|
# handle_request before self.timeout was available.
|
||
|
timeout = self.socket.gettimeout()
|
||
|
if timeout is None:
|
||
|
timeout = self.timeout
|
||
|
elif self.timeout is not None:
|
||
|
timeout = min(timeout, self.timeout)
|
||
|
fd_sets = _eintr_retry(select.select, [self], [], [], timeout)
|
||
|
if not fd_sets[0]:
|
||
|
self.handle_timeout()
|
||
|
return
|
||
|
self._handle_request_noblock()
|
||
|
|
||
|
def _handle_request_noblock(self):
|
||
|
"""Handle one request, without blocking.
|
||
|
|
||
|
I assume that select.select has returned that the socket is
|
||
|
readable before this function was called, so there should be
|
||
|
no risk of blocking in get_request().
|
||
|
"""
|
||
|
try:
|
||
|
request, client_address = self.get_request()
|
||
|
except socket.error:
|
||
|
return
|
||
|
if self.verify_request(request, client_address):
|
||
|
try:
|
||
|
self.process_request(request, client_address)
|
||
|
except:
|
||
|
self.handle_error(request, client_address)
|
||
|
self.shutdown_request(request)
|
||
|
|
||
|
def handle_timeout(self):
|
||
|
"""Called if no new request arrives within self.timeout.
|
||
|
|
||
|
Overridden by ForkingMixIn.
|
||
|
"""
|
||
|
pass
|
||
|
|
||
|
def verify_request(self, request, client_address):
|
||
|
"""Verify the request. May be overridden.
|
||
|
|
||
|
Return True if we should proceed with this request.
|
||
|
|
||
|
"""
|
||
|
return True
|
||
|
|
||
|
def process_request(self, request, client_address):
|
||
|
"""Call finish_request.
|
||
|
|
||
|
Overridden by ForkingMixIn and ThreadingMixIn.
|
||
|
|
||
|
"""
|
||
|
self.finish_request(request, client_address)
|
||
|
self.shutdown_request(request)
|
||
|
|
||
|
def server_close(self):
|
||
|
"""Called to clean-up the server.
|
||
|
|
||
|
May be overridden.
|
||
|
|
||
|
"""
|
||
|
pass
|
||
|
|
||
|
def finish_request(self, request, client_address):
|
||
|
"""Finish one request by instantiating RequestHandlerClass."""
|
||
|
self.RequestHandlerClass(request, client_address, self)
|
||
|
|
||
|
def shutdown_request(self, request):
|
||
|
"""Called to shutdown and close an individual request."""
|
||
|
self.close_request(request)
|
||
|
|
||
|
def close_request(self, request):
|
||
|
"""Called to clean up an individual request."""
|
||
|
pass
|
||
|
|
||
|
def handle_error(self, request, client_address):
|
||
|
"""Handle an error gracefully. May be overridden.
|
||
|
|
||
|
The default is to print a traceback and continue.
|
||
|
|
||
|
"""
|
||
|
print('-'*40)
|
||
|
print('Exception happened during processing of request from', end=' ')
|
||
|
print(client_address)
|
||
|
import traceback
|
||
|
traceback.print_exc() # XXX But this goes to stderr!
|
||
|
print('-'*40)
|
||
|
|
||
|
|
||
|
class TCPServer(BaseServer):
|
||
|
|
||
|
"""Base class for various socket-based server classes.
|
||
|
|
||
|
Defaults to synchronous IP stream (i.e., TCP).
|
||
|
|
||
|
Methods for the caller:
|
||
|
|
||
|
- __init__(server_address, RequestHandlerClass, bind_and_activate=True)
|
||
|
- serve_forever(poll_interval=0.5)
|
||
|
- shutdown()
|
||
|
- handle_request() # if you don't use serve_forever()
|
||
|
- fileno() -> int # for select()
|
||
|
|
||
|
Methods that may be overridden:
|
||
|
|
||
|
- server_bind()
|
||
|
- server_activate()
|
||
|
- get_request() -> request, client_address
|
||
|
- handle_timeout()
|
||
|
- verify_request(request, client_address)
|
||
|
- process_request(request, client_address)
|
||
|
- shutdown_request(request)
|
||
|
- close_request(request)
|
||
|
- handle_error()
|
||
|
|
||
|
Methods for derived classes:
|
||
|
|
||
|
- finish_request(request, client_address)
|
||
|
|
||
|
Class variables that may be overridden by derived classes or
|
||
|
instances:
|
||
|
|
||
|
- timeout
|
||
|
- address_family
|
||
|
- socket_type
|
||
|
- request_queue_size (only for stream sockets)
|
||
|
- allow_reuse_address
|
||
|
|
||
|
Instance variables:
|
||
|
|
||
|
- server_address
|
||
|
- RequestHandlerClass
|
||
|
- socket
|
||
|
|
||
|
"""
|
||
|
|
||
|
address_family = socket.AF_INET
|
||
|
|
||
|
socket_type = socket.SOCK_STREAM
|
||
|
|
||
|
request_queue_size = 5
|
||
|
|
||
|
allow_reuse_address = False
|
||
|
|
||
|
def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True):
|
||
|
"""Constructor. May be extended, do not override."""
|
||
|
BaseServer.__init__(self, server_address, RequestHandlerClass)
|
||
|
self.socket = socket.socket(self.address_family,
|
||
|
self.socket_type)
|
||
|
if bind_and_activate:
|
||
|
self.server_bind()
|
||
|
self.server_activate()
|
||
|
|
||
|
def server_bind(self):
|
||
|
"""Called by constructor to bind the socket.
|
||
|
|
||
|
May be overridden.
|
||
|
|
||
|
"""
|
||
|
if self.allow_reuse_address:
|
||
|
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
|
||
|
self.socket.bind(self.server_address)
|
||
|
self.server_address = self.socket.getsockname()
|
||
|
|
||
|
def server_activate(self):
|
||
|
"""Called by constructor to activate the server.
|
||
|
|
||
|
May be overridden.
|
||
|
|
||
|
"""
|
||
|
self.socket.listen(self.request_queue_size)
|
||
|
|
||
|
def server_close(self):
|
||
|
"""Called to clean-up the server.
|
||
|
|
||
|
May be overridden.
|
||
|
|
||
|
"""
|
||
|
self.socket.close()
|
||
|
|
||
|
def fileno(self):
|
||
|
"""Return socket file number.
|
||
|
|
||
|
Interface required by select().
|
||
|
|
||
|
"""
|
||
|
return self.socket.fileno()
|
||
|
|
||
|
def get_request(self):
|
||
|
"""Get the request and client address from the socket.
|
||
|
|
||
|
May be overridden.
|
||
|
|
||
|
"""
|
||
|
return self.socket.accept()
|
||
|
|
||
|
def shutdown_request(self, request):
|
||
|
"""Called to shutdown and close an individual request."""
|
||
|
try:
|
||
|
#explicitly shutdown. socket.close() merely releases
|
||
|
#the socket and waits for GC to perform the actual close.
|
||
|
request.shutdown(socket.SHUT_WR)
|
||
|
except socket.error:
|
||
|
pass #some platforms may raise ENOTCONN here
|
||
|
self.close_request(request)
|
||
|
|
||
|
def close_request(self, request):
|
||
|
"""Called to clean up an individual request."""
|
||
|
request.close()
|
||
|
|
||
|
|
||
|
class UDPServer(TCPServer):
|
||
|
|
||
|
"""UDP server class."""
|
||
|
|
||
|
allow_reuse_address = False
|
||
|
|
||
|
socket_type = socket.SOCK_DGRAM
|
||
|
|
||
|
max_packet_size = 8192
|
||
|
|
||
|
def get_request(self):
|
||
|
data, client_addr = self.socket.recvfrom(self.max_packet_size)
|
||
|
return (data, self.socket), client_addr
|
||
|
|
||
|
def server_activate(self):
|
||
|
# No need to call listen() for UDP.
|
||
|
pass
|
||
|
|
||
|
def shutdown_request(self, request):
|
||
|
# No need to shutdown anything.
|
||
|
self.close_request(request)
|
||
|
|
||
|
def close_request(self, request):
|
||
|
# No need to close anything.
|
||
|
pass
|
||
|
|
||
|
class ForkingMixIn:
|
||
|
|
||
|
"""Mix-in class to handle each request in a new process."""
|
||
|
|
||
|
timeout = 300
|
||
|
active_children = None
|
||
|
max_children = 40
|
||
|
|
||
|
def collect_children(self):
|
||
|
"""Internal routine to wait for children that have exited."""
|
||
|
if self.active_children is None: return
|
||
|
while len(self.active_children) >= self.max_children:
|
||
|
# XXX: This will wait for any child process, not just ones
|
||
|
# spawned by this library. This could confuse other
|
||
|
# libraries that expect to be able to wait for their own
|
||
|
# children.
|
||
|
try:
|
||
|
pid, status = os.waitpid(0, 0)
|
||
|
except os.error:
|
||
|
pid = None
|
||
|
if pid not in self.active_children: continue
|
||
|
self.active_children.remove(pid)
|
||
|
|
||
|
# XXX: This loop runs more system calls than it ought
|
||
|
# to. There should be a way to put the active_children into a
|
||
|
# process group and then use os.waitpid(-pgid) to wait for any
|
||
|
# of that set, but I couldn't find a way to allocate pgids
|
||
|
# that couldn't collide.
|
||
|
for child in self.active_children:
|
||
|
try:
|
||
|
pid, status = os.waitpid(child, os.WNOHANG)
|
||
|
except os.error:
|
||
|
pid = None
|
||
|
if not pid: continue
|
||
|
try:
|
||
|
self.active_children.remove(pid)
|
||
|
except ValueError as e:
|
||
|
raise ValueError('%s. x=%d and list=%r' % (e.message, pid,
|
||
|
self.active_children))
|
||
|
|
||
|
def handle_timeout(self):
|
||
|
"""Wait for zombies after self.timeout seconds of inactivity.
|
||
|
|
||
|
May be extended, do not override.
|
||
|
"""
|
||
|
self.collect_children()
|
||
|
|
||
|
def service_actions(self):
|
||
|
"""Collect the zombie child processes regularly in the ForkingMixIn.
|
||
|
|
||
|
service_actions is called in the BaseServer's serve_forver loop.
|
||
|
"""
|
||
|
self.collect_children()
|
||
|
|
||
|
def process_request(self, request, client_address):
|
||
|
"""Fork a new subprocess to process the request."""
|
||
|
pid = os.fork()
|
||
|
if pid:
|
||
|
# Parent process
|
||
|
if self.active_children is None:
|
||
|
self.active_children = []
|
||
|
self.active_children.append(pid)
|
||
|
self.close_request(request)
|
||
|
return
|
||
|
else:
|
||
|
# Child process.
|
||
|
# This must never return, hence os._exit()!
|
||
|
try:
|
||
|
self.finish_request(request, client_address)
|
||
|
self.shutdown_request(request)
|
||
|
os._exit(0)
|
||
|
except:
|
||
|
try:
|
||
|
self.handle_error(request, client_address)
|
||
|
self.shutdown_request(request)
|
||
|
finally:
|
||
|
os._exit(1)
|
||
|
|
||
|
|
||
|
class ThreadingMixIn:
|
||
|
"""Mix-in class to handle each request in a new thread."""
|
||
|
|
||
|
# Decides how threads will act upon termination of the
|
||
|
# main process
|
||
|
daemon_threads = False
|
||
|
|
||
|
def process_request_thread(self, request, client_address):
|
||
|
"""Same as in BaseServer but as a thread.
|
||
|
|
||
|
In addition, exception handling is done here.
|
||
|
|
||
|
"""
|
||
|
try:
|
||
|
self.finish_request(request, client_address)
|
||
|
self.shutdown_request(request)
|
||
|
except:
|
||
|
self.handle_error(request, client_address)
|
||
|
self.shutdown_request(request)
|
||
|
|
||
|
def process_request(self, request, client_address):
|
||
|
"""Start a new thread to process the request."""
|
||
|
t = threading.Thread(target = self.process_request_thread,
|
||
|
args = (request, client_address))
|
||
|
t.daemon = self.daemon_threads
|
||
|
t.start()
|
||
|
|
||
|
|
||
|
class ForkingUDPServer(ForkingMixIn, UDPServer): pass
|
||
|
class ForkingTCPServer(ForkingMixIn, TCPServer): pass
|
||
|
|
||
|
class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass
|
||
|
class ThreadingTCPServer(ThreadingMixIn, TCPServer): pass
|
||
|
|
||
|
if hasattr(socket, 'AF_UNIX'):
|
||
|
|
||
|
class UnixStreamServer(TCPServer):
|
||
|
address_family = socket.AF_UNIX
|
||
|
|
||
|
class UnixDatagramServer(UDPServer):
|
||
|
address_family = socket.AF_UNIX
|
||
|
|
||
|
class ThreadingUnixStreamServer(ThreadingMixIn, UnixStreamServer): pass
|
||
|
|
||
|
class ThreadingUnixDatagramServer(ThreadingMixIn, UnixDatagramServer): pass
|
||
|
|
||
|
class BaseRequestHandler:
|
||
|
|
||
|
"""Base class for request handler classes.
|
||
|
|
||
|
This class is instantiated for each request to be handled. The
|
||
|
constructor sets the instance variables request, client_address
|
||
|
and server, and then calls the handle() method. To implement a
|
||
|
specific service, all you need to do is to derive a class which
|
||
|
defines a handle() method.
|
||
|
|
||
|
The handle() method can find the request as self.request, the
|
||
|
client address as self.client_address, and the server (in case it
|
||
|
needs access to per-server information) as self.server. Since a
|
||
|
separate instance is created for each request, the handle() method
|
||
|
can define arbitrary other instance variariables.
|
||
|
|
||
|
"""
|
||
|
|
||
|
def __init__(self, request, client_address, server):
|
||
|
self.request = request
|
||
|
self.client_address = client_address
|
||
|
self.server = server
|
||
|
self.setup()
|
||
|
try:
|
||
|
self.handle()
|
||
|
finally:
|
||
|
self.finish()
|
||
|
|
||
|
def setup(self):
|
||
|
pass
|
||
|
|
||
|
def handle(self):
|
||
|
pass
|
||
|
|
||
|
def finish(self):
|
||
|
pass
|
||
|
|
||
|
|
||
|
# The following two classes make it possible to use the same service
|
||
|
# class for stream or datagram servers.
|
||
|
# Each class sets up these instance variables:
|
||
|
# - rfile: a file object from which receives the request is read
|
||
|
# - wfile: a file object to which the reply is written
|
||
|
# When the handle() method returns, wfile is flushed properly
|
||
|
|
||
|
|
||
|
class StreamRequestHandler(BaseRequestHandler):
|
||
|
|
||
|
"""Define self.rfile and self.wfile for stream sockets."""
|
||
|
|
||
|
# Default buffer sizes for rfile, wfile.
|
||
|
# We default rfile to buffered because otherwise it could be
|
||
|
# really slow for large data (a getc() call per byte); we make
|
||
|
# wfile unbuffered because (a) often after a write() we want to
|
||
|
# read and we need to flush the line; (b) big writes to unbuffered
|
||
|
# files are typically optimized by stdio even when big reads
|
||
|
# aren't.
|
||
|
rbufsize = -1
|
||
|
wbufsize = 0
|
||
|
|
||
|
# A timeout to apply to the request socket, if not None.
|
||
|
timeout = None
|
||
|
|
||
|
# Disable nagle algorithm for this socket, if True.
|
||
|
# Use only when wbufsize != 0, to avoid small packets.
|
||
|
disable_nagle_algorithm = False
|
||
|
|
||
|
def setup(self):
|
||
|
self.connection = self.request
|
||
|
if self.timeout is not None:
|
||
|
self.connection.settimeout(self.timeout)
|
||
|
if self.disable_nagle_algorithm:
|
||
|
self.connection.setsockopt(socket.IPPROTO_TCP,
|
||
|
socket.TCP_NODELAY, True)
|
||
|
self.rfile = self.connection.makefile('rb', self.rbufsize)
|
||
|
self.wfile = self.connection.makefile('wb', self.wbufsize)
|
||
|
|
||
|
def finish(self):
|
||
|
if not self.wfile.closed:
|
||
|
try:
|
||
|
self.wfile.flush()
|
||
|
except socket.error:
|
||
|
# An final socket error may have occurred here, such as
|
||
|
# the local error ECONNABORTED.
|
||
|
pass
|
||
|
self.wfile.close()
|
||
|
self.rfile.close()
|
||
|
|
||
|
|
||
|
class DatagramRequestHandler(BaseRequestHandler):
|
||
|
|
||
|
# XXX Regrettably, I cannot get this working on Linux;
|
||
|
# s.recvfrom() doesn't return a meaningful client address.
|
||
|
|
||
|
"""Define self.rfile and self.wfile for datagram sockets."""
|
||
|
|
||
|
def setup(self):
|
||
|
from io import BytesIO
|
||
|
self.packet, self.socket = self.request
|
||
|
self.rfile = BytesIO(self.packet)
|
||
|
self.wfile = BytesIO()
|
||
|
|
||
|
def finish(self):
|
||
|
self.socket.sendto(self.wfile.getvalue(), self.client_address)
|