learning python sockets: msgq, the revenge

git-svn-id: svn://bind10.isc.org/svn/bind10/branches/parkinglot@331 e5f2f494-b856-4b98-b285-d166d9295462

configure.ac

@@ -64,8 +64,10 @@ AC_CONFIG_FILES([Makefile
                ])
 AC_OUTPUT([src/bin/bind-cfgd/bind-cfgd
            src/bin/bind10/bind10
+	   src/bin/pymsgq/msgq
           ], [
            chmod +x src/bin/bind-cfgd/bind-cfgd
            chmod +x src/bin/bind10/bind10
+           chmod +x src/bin/pymsgq/msgq
           ])
 AC_OUTPUT

src/bin/pymsgq/msgq.in

+#! /bin/sh
+
+PYTHON_EXEC=${PYTHON_EXEC:-python3.1}
+export PYTHON_EXEC
+
+MYPATH_PATH=@abs_top_srcdir@/src/bin/pymsgq
+
+PYTHONPATH=@abs_top_srcdir@/src/lib/cc/python:${abs_top_src_dir}/lib/cc/python/ISC
+export PYTHONPATH
+
+cd ${MYPATH_PATH}
+exec ${PYTHON_EXEC} -O msgq.py $*

src/bin/pymsgq/msgq.py

+"""\
+This code implements a Python version of the msgq daemon.
+
+This replaces the C version, which relied upon the BIND 9 "libisc"
+libraries.
+"""
+
+import subprocess
+import signal
+import os
+import socket
+import sys
+import re
+import errno
+import time
+import select
+import pprint
+from optparse import OptionParser, OptionValueError
+
+import ISC.CC
+
+# This is the version that gets displayed to the user.
+__version__ = "v20091030 (Paving the DNS Parking Lot)"
+
+class MsgQ:
+    """Message Queue class."""
+    def __init__(self, c_channel_port=9912, verbose=False):
+        """Initialize the MsgQ master.
+        
+        The c_channel_port specifies the TCP/IP port that the msgq
+        process listens on. If verbose is True, then the MsgQ reports
+        what it is doing.
+        """
+        self.verbose = True
+        self.c_channel_port = c_channel_port
+        self.poller = None
+        self.runnable = False
+        self.listen_socket = False
+        self.sockets = {}
+
+    def setup_poller(self):
+        """Set up the poll thing.  Internal function."""
+        self.poller = select.poll()
+
+    def setup_listener(self):
+        """Set up the listener socket.  Internal function."""
+        self.listen_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.listen_socket.bind(("127.0.0.1", self.c_channel_port))
+        self.listen_socket.listen(1024)
+        self.listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+
+        self.poller.register(self.listen_socket, select.POLLIN)
+
+    def setup(self):
+        """Configure listener socket, polling, etc."""
+
+        self.setup_poller()
+        self.setup_listener()
+
+        if self.verbose:
+            sys.stdout.write("Listening\n")
+        
+        self.runnable = True
+
+    def process_accept(self):
+        newsocket, ipaddr = self.listen_socket.accept()
+        sys.stderr.write("Connection\n")
+        self.sockets[newsocket.fileno()] = newsocket
+        self.poller.register(newsocket, select.POLLIN)
+
+    def process_socket(self, fd):
+        sock = self.sockets[fd]
+        if sock == None:
+            sys.stderr.write("Got read on Strange Socket fd %d\n" % fd)
+            return
+        sys.stderr.write("Got read on fd %d\n" %fd)
+        self.process_packet(fd, sock)
+
+    def process_packet(self, fd, sock):
+        data = sock.recv(4)
+        if len(data) == 0:
+            self.poller.unregister(sock)
+            sock.close()
+            self.sockets[fd] = None
+            sys.stderr.write("Closing socket fd %d\n" % fd)
+            return
+        sys.stderr.write("Got data: %s\n" % data)
+
+    def run(self):
+        """Process messages.  Forever.  Mostly."""
+
+        while True:
+            try:
+                events = self.poller.poll()
+            except select.error as err:
+                if err.args[0] == errno.EINTR:
+                    events = []
+                else:
+                    sys.stderr.write("Error with poll(): %s\n" % err)
+                    break
+            for (fd, event) in events:
+                if fd == self.listen_socket.fileno():
+                    self.process_accept()
+                else:
+                    self.process_socket(fd)
+
+    def shutdown(self):
+        """Stop the MsgQ master."""
+        if self.verbose:
+            sys.stdout.write("Stopping the server.\n")
+        self.listen_socket.close()
+
+if __name__ == "__main__":
+    def check_port(option, opt_str, value, parser):
+        """Function to insure that the port we are passed is actually 
+        a valid port number. Used by OptionParser() on startup."""
+        intval = int(value)
+        if (intval < 0) or (intval > 65535):
+            raise OptionValueError("%s requires a port number (0-65535)" % opt_str)
+        parser.values.msgq_port = intval
+
+    # Parse any command-line options.
+    parser = OptionParser(version=__version__)
+    parser.add_option("-v", "--verbose", dest="verbose", action="store_true",
+                      help="display more about what is going on")
+    parser.add_option("-m", "--msgq-port", dest="msgq_port", type="string",
+                      action="callback", callback=check_port, default="9912",
+                      help="port the msgq daemon will use")
+    (options, args) = parser.parse_args()
+
+    # Announce startup.
+    if options.verbose:
+        sys.stdout.write("MsgQ %s\n" % __version__)
+
+    msgq = MsgQ(int(options.msgq_port), options.verbose)
+
+    setup_result = msgq.setup()
+    if setup_result:
+        sys.stderr.write("Error on startup: %s\n" % setup_result)
+        sys.exit(1)
+
+    msgq.run()
+
+    msgq.shutdown()