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#############################################################
## xend/console.py -- Console-management functions for Xend
## Copyright (c) 2004, K A Fraser (University of Cambridge)
#############################################################
import errno, re, os, select, signal, socket, struct, sys
##
## interface:
## Each control interface owns an instance of this class, which manages
## the current state of the console interface. Normally a console interface
## will be one of two state:
## LISTENING: listening for a connection on TCP port 'self.port'
## CONNECTED: sending/receiving console data on TCP port 'self.port'
##
## A dictionary of all active interfaces, indexed by TCP socket descriptor,
## is accessible as 'interface.interface_list'.
##
## NB. When a class instance is to be destroyed you *must* call the 'close'
## method. Otherwise a stale reference will eb left in the interface list.
##
class interface:
# The various states that a console interface may be in.
CLOSED = 0 # No console activity
LISTENING = 1 # Listening on port 'self.port'. Socket object 'self.sock'.
CONNECTED = 2 # Active connection on 'self.port'. Socket obj 'self.sock'.
# Dictionary of all active (non-closed) console interfaces.
interface_list = {}
# NB. 'key' is an opaque value that has no meaning in this class.
def __init__(self, port, key):
self.status = interface.CLOSED
self.port = port
self.key = key
# Is this interface closed (inactive)?
def closed(self):
return self.status == interface.CLOSED
# Is this interface listening?
def listening(self):
return self.status == interface.LISTENING
# Is this interface active and connected?
def connected(self):
return self.status == interface.CONNECTED
# Close the interface, if it is not closed already.
def close(self):
if not self.closed():
del interface.interface_list[self.sock.fileno()]
self.sock.close()
del self.sock
self.status = interface.CLOSED
# Move the interface into the 'listening' state. Opens a new listening
# socket and updates 'interface_list'.
def listen(self):
# Close old socket (if any), and create a fresh one.
self.close()
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
try:
# Turn the new socket into a non-blocking listener.
self.sock.setblocking(False)
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.sock.bind(('', self.port))
self.sock.listen(1)
# Announce the new status of thsi interface.
self.status = interface.LISTENING
interface.interface_list[self.sock.fileno()] = self
except:
# In case of trouble ensure we get rid of dangling socket reference
self.sock.close()
del self.sock
raise
# Move a listening interface into the 'connected' state.
def connect(self):
# Pick up a new connection, if one is available.
try:
(sock, addr) = self.sock.accept()
except:
return 0
sock.setblocking(False)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# Close the listening socket.
self.sock.close()
# Publish the new socket and the new interface state.
self.sock = sock
self.status = interface.CONNECTED
interface.interface_list[self.sock.fileno()] = self
return 1
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