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server.py
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server.py
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# -*- encoding: utf-8 -*-
#Reference: https://github.com/lunemec/python-chat
import os
import select
import socket
import sys
import signal
from time import sleep
import datetime
from Crypto.PublicKey import RSA
from Crypto.Signature import PKCS1_PSS
from Crypto.Hash import SHA256
from communication import send, receive
class ChatServer(object):
def __init__(self, address='127.0.0.1', port=8080):
self.clients = 0
# Client map
self.clientmap = {}
# Output socket list
self.outputsock = []
self.server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.server.bind((address, int(port)))
print 'Generating RSA keys ....'
self.server_privkey = RSA.generate(4096, os.urandom)
self.server_pubkey = self.server_privkey.publickey()
self.sign = self.server_privkey
print 'Chat Room Server started at port', port, '...'
self.server.listen(10)
# Trap keyboard interrupts
signal.signal(signal.SIGINT, self.signalhandler)
def signalhandler(self, signal, frame):
# Close the server
print 'Shutting down server...'
# Close existing client sockets
for o in self.outputsock:
o.close()
self.server.close()
def getname(self, client):
# Return the printable name of the
# client, given its socket...
info = self.clientmap[client]
host, name = info[0][0], info[1]
return '@'.join((name, host))
def get_just_name(self, client):
return self.clientmap[client][1]
def send_encrypted(self, to_who, message, name):
try:
encryptor = self.clientmap[to_who][2]
msg = encryptor.encrypt(message, 0)
msg = msg[0]
message_hash = SHA256.new()
message_hash.update(msg)
signkey = self.sign
#Append Signature
signer = PKCS1_PSS.new(signkey)
signature = signer.sign(message_hash)
msg = '%s#^[[%s' % (msg, signature)
#print msg
send(to_who, msg)
except IOError:
send(to_who, 'PLAIN: cannot find public key for: %s' % name)
def verify_signature(self, client, message, signature):
try:
key = self.clientmap[client][2]
msg_hash = SHA256.new()
msg_hash.update(message)
verifier = PKCS1_PSS.new(key)
return verifier.verify(msg_hash, signature)
except IOError:
return False
def serve(self):
inputs = [self.server, sys.stdin]
self.outputsock = []
running = 1
while running:
try:
inputready, outputready, exceptready = select.select(inputs, self.outputsock, [])
except select.error:
break
except socket.error:
break
for s in inputready:
if s == self.server:
# handle the server socket
client, address = self.server.accept()
print 'Chat Server: got connection %d from %s' % (client.fileno(), address)
# Get client public key and send our public key
pubkey = RSA.importKey(receive(client))
send(client, self.server_pubkey.exportKey())
# Read the login name
cname = receive(client).split('NAME: ')[1]
# Compute client name and send back
self.clients += 1
send(client, 'CLIENT: ' + str(address[0]))
inputs.append(client)
self.clientmap[client] = (address, cname, pubkey)
# Send joining information to other clients
msg = '\n(New client (%d) entered the chat room : %s)' % (self.clients, self.getname(client))
for o in self.outputsock:
try:
self.send_encrypted(o, msg, self.get_just_name(o))
except socket.error:
self.outputsock.remove(o)
inputs.remove(o)
self.outputsock.append(client)
elif s == sys.stdin:
# handle standard input
sys.stdin.readline()
running = 0
else:
# handle all other sockets
try:
data = receive(s)
if data:
dataparts = data.split('#^[[')
signature = dataparts[1]
data = dataparts[0]
verified = self.verify_signature(s, data, signature)
data = self.server_privkey.decrypt(data)
word = "Check online users"
user_list = ["Online Users:"]
if word in data:
#for item in inputs:
for o in self.outputsock:
ur = self.get_just_name(o)
user_list.append(ur)
user_list = str(user_list)
print user_list
for o in self.outputsock:
#self.send_encrypted(o, msg, self.get_just_name(o))
self.send_encrypted(o, user_list, self.get_just_name(o))
if data != '\x00':
if verified:
data = '%s [Client Signature Verified:OK]' % data
else:
data = '%s [Not verified]' % data
# Send as new client's message...
msg = '\n# [' + self.getname(s) + ']>> ' + data
# Send data to all except ourselves
for o in self.outputsock:
if o != s:
self.send_encrypted(o, msg, self.get_just_name(s))
else:
print 'Chatserver: Client %d disconnected' % s.fileno()
self.clients -= 1
s.close()
inputs.remove(s)
self.outputsock.remove(s)
# Send client leaving information to others
msg = '\n(Left the Chat Room: Client from %s)' % self.getname(s)
for o in self.outputsock:
self.send_encrypted(o, msg, self.get_just_name(o))
except socket.error:
# Remove
inputs.remove(s)
self.outputsock.remove(s)
sleep(0.1)
self.server.close()
if __name__ == "__main__":
if len(sys.argv) < 3:
sys.exit('Usage: %s listen_ip listen_port' % sys.argv[0])
ChatServer(sys.argv[1], sys.argv[2]).serve()