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Diffstat (limited to 'Lib/dos_8x3/socketse.py')
| -rwxr-xr-x | Lib/dos_8x3/socketse.py | 413 |
1 files changed, 0 insertions, 413 deletions
diff --git a/Lib/dos_8x3/socketse.py b/Lib/dos_8x3/socketse.py deleted file mode 100755 index ecd405f..0000000 --- a/Lib/dos_8x3/socketse.py +++ /dev/null @@ -1,413 +0,0 @@ -"""Generic socket server classes. - -This module tries to capture the various aspects of defining a server: - -- address family: - - AF_INET: 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) -- 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 four classes in an inheritance diagram that represent -synchronous servers of four types: - - +-----------+ +------------------+ - | 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 ForkingServer and ThreadingServer 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! - -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 mix-in request handler -classes 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 reqd 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's -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 can't 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? - -""" - - -__version__ = "0.2" - - -import socket -import sys -import os - - -class TCPServer: - - """Base class for various socket-based server classes. - - Defaults to synchronous IP stream (i.e., TCP). - - Methods for the caller: - - - __init__(server_address, RequestHandlerClass) - - serve_forever() - - 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 - - verify_request(request, client_address) - - process_request(request, client_address) - - handle_error() - - Methods for derived classes: - - - finish_request(request, client_address) - - Class variables that may be overridden by derived classes or - instances: - - - address_family - - socket_type - - request_queue_size (only for stream sockets) - - Instance variables: - - - server_address - - RequestHandlerClass - - socket - - """ - - address_family = socket.AF_INET - - socket_type = socket.SOCK_STREAM - - request_queue_size = 5 - - def __init__(self, server_address, RequestHandlerClass): - """Constructor. May be extended, do not override.""" - self.server_address = server_address - self.RequestHandlerClass = RequestHandlerClass - self.socket = socket.socket(self.address_family, - self.socket_type) - self.server_bind() - self.server_activate() - - def server_bind(self): - """Called by constructor to bind the socket. - - May be overridden. - - """ - self.socket.bind(self.server_address) - - def server_activate(self): - """Called by constructor to activate the server. - - May be overridden. - - """ - self.socket.listen(self.request_queue_size) - - def fileno(self): - """Return socket file number. - - Interface required by select(). - - """ - return self.socket.fileno() - - def serve_forever(self): - """Handle one request at a time until doomsday.""" - while 1: - self.handle_request() - - # The distinction between handling, getting, processing and - # finishing a request is fairly arbitrary. Remember: - # - # - handle_request() is the top-level call. It calls - # 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.""" - request, client_address = self.get_request() - if self.verify_request(request, client_address): - try: - self.process_request(request, client_address) - except: - self.handle_error(request, client_address) - - def get_request(self): - """Get the request and client address from the socket. - - May be overridden. - - """ - return self.socket.accept() - - def verify_request(self, request, client_address): - """Verify the request. May be overridden. - - Return true if we should proceed with this request. - - """ - return 1 - - def process_request(self, request, client_address): - """Call finish_request. - - Overridden by ForkingMixIn and ThreadingMixIn. - - """ - self.finish_request(request, client_address) - - def finish_request(self, request, client_address): - """Finish one request by instantiating RequestHandlerClass.""" - self.RequestHandlerClass(request, client_address, self) - - def handle_error(self, request, client_address): - """Handle an error gracefully. May be overridden. - - The default is to print a traceback and continue. - - """ - exc, value, tb = sys.exc_type, sys.exc_value, sys.exc_traceback - print '-'*40 - print 'Exception happened during processing of request from', - print client_address - import traceback - traceback.print_exception(exc, value, tb) - print '-'*40 - - -class UDPServer(TCPServer): - - """UDP server class.""" - - socket_type = socket.SOCK_DGRAM - - max_packet_size = 8192 - - def get_request(self): - return self.socket.recvfrom(self.max_packet_size) - - -if hasattr(socket, 'AF_UNIX'): - - class UnixStreamServer(TCPServer): - - address_family = socket.AF_UNIX - - - class UnixDatagramServer(UDPServer): - - address_family = socket.AF_UNIX - - -class ForkingMixIn: - - """Mix-in class to handle each request in a new process.""" - - active_children = None - - def collect_children(self): - """Internal routine to wait for died children.""" - while self.active_children: - pid, status = os.waitpid(0, os.WNOHANG) - if not pid: break - self.active_children.remove(pid) - - def process_request(self, request, client_address): - """Fork a new subprocess to process the request.""" - self.collect_children() - pid = os.fork() - if pid: - # Parent process - if self.active_children is None: - self.active_children = [] - self.active_children.append(pid) - return - else: - # Child process. - # This must never return, hence os._exit()! - try: - self.finish_request(request, client_address) - os._exit(0) - except: - try: - self.handle_error(request, - client_address) - finally: - os._exit(1) - - -class ThreadingMixIn: - - """Mix-in class to handle each request in a new thread.""" - - def process_request(self, request, client_address): - """Start a new thread to process the request.""" - import thread - thread.start_new_thread(self.finish_request, - (request, client_address)) - - -class ForkingUDPServer(ForkingMixIn, UDPServer): pass -class ForkingTCPServer(ForkingMixIn, TCPServer): pass - -class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass -class ThreadingTCPServer(ThreadingMixIn, TCPServer): 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_request, 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 - try: - self.setup() - self.handle() - self.finish() - finally: - sys.exc_traceback = None # Help garbage collection - - def setup(self): - pass - - def __del__(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.""" - - def setup(self): - self.connection = self.request - self.rfile = self.connection.makefile('rb', 0) - self.wfile = self.connection.makefile('wb', 0) - - def finish(self): - self.wfile.flush() - - -class DatagramRequestHandler(BaseRequestHandler): - - """Define self.rfile and self.wfile for datagram sockets.""" - - def setup(self): - import StringIO - self.packet, self.socket = self.request - self.rfile = StringIO.StringIO(self.packet) - self.wfile = StringIO.StringIO(self.packet) - - def finish(self): - self.socket.send(self.wfile.getvalue()) |