#	A simple 'chat' server.  Creates a server on port 4000.
#	Users telnet to your machine, port 4000, and can chat with each
#	other.  Use "quit" to disconnect yourself, and "shutdown" to
#	shut down the server.  Requires sockets.
#
#	7/31/96	J. Strout		http://www.strout.net/
# import needed modules:

from socket import *		# get sockets, for well, sockets
import string				# string functions
import time					# for sleep(1) function

# define global variables

HOST = ''				# Symbolic name meaning the local host
PORT = 4000				# Arbitrary non-privileged server
endl = "\r\n"			# standard terminal line ending

userlist = []			# list of connected users
done = 0				# set to 1 to shut this down

kAskName = 0			# some constants used to flag
kWaitName = 1			#	the state of each user
kOK = 2


# class to store info about connected users

class User:
	def __init__(self):
		self.name = ""
		self.addr = ""
		self.conn = None
		self.step = kAskName

	def Idle(self):
		if self.step == kAskName: self.AskName()

	def AskName(self):
		self.conn.send("Name? ")
		self.step = kWaitName

	def HandleMsg(self, msg):
		print "Handling message: ",msg
		global userlist

		# if waiting for name, record it
		if self.step == kWaitName:
			# try to trap garb initiall sent by some telnets:
			if len(msg) < 2 or msg=="#": return
			print "Setting name to: ",msg
			self.name = msg
			self.step = kOK
			self.conn.send("Hello, "+self.name+endl)
			broadcast(self.name+" has connected."+endl)
			return

		# check for commands
		if msg == "quit":
			broadcast(self.name+" has quit.\n")
			self.conn.close()
			userlist.remove(self)
			return

		# otherwise, broadcast msg
		broadcast( self.name+": "+msg+endl )


# routine to check for incoming connections
def pollNewConn():
	try:
		conn, addr = s.accept()
	except:
		return None
	print "Connection from", addr
	conn.setblocking(0)
	user = User();
	user.conn = conn
	user.addr = addr
	return user


# routine to broadcast a message to all connected users

def broadcast(msg):
	for u in userlist:
		u.conn.send(msg)


# MAIN PROGRAM


# set up the server

s = socket(AF_INET, SOCK_STREAM)
bing = (HOST, PORT)
s.bind(bing)
s.setblocking(0)
s.listen(1)
print "Waiting for connection(s)..."

# loop until done, handling connections and incoming messages

while not done:
	time.sleep(1)		# sleep to reduce processor usage
	u = pollNewConn()	# check for incoming connections
	if u:
		userlist.append(u)
		print len(userlist),"connection(s)"

	for u in userlist:	# check all connected users
		u.Idle()
		try:
			data = u.conn.recv(1024)
			data = filter(lambda x: x>=' ' and x<='z', data)
			data = string.strip(data)
			if data:
				print "From",u.name,': ['+data+']'
				u.HandleMsg(data)
				if data == "shutdown": done=1
		except:
			pass

for u in userlist:
	u.conn.close()