def monitor(server_w, id):
conn = Channel()
server_w((id, conn.writer()))
inp = conn.reader()
# Monitor the first three messages an then kill the connection
for _ in range(3):
print "[MONITOR] %s" % inp()
poison(inp)
def do_service(outp):
""" job process initiated by the server. Handles communication with the
client after connection has been established
:param outp: Writer to connected client
"""
conn = Channel()
outp(conn.writer())
inp = conn.reader()
while True:
msg = inp()
outp('Simulated HTTP Server got: ' + msg)
def server(whitelist, swear_words, IP, monitors_r):
monitor_writers = {}
while True:
monitor_chan = Channel()
p, msg = AltSelect(InputGuard(IP), InputGuard(monitors_r))
if p == IP:
(addr, port, conn) = msg
Spawn(firewall(whitelist, swear_words, addr, port, conn,
monitor_chan.reader()))
monitor_writers[conn_to_id(addr, port)] = (monitor_chan.writer())
else:
(id, conn) = msg
monitor_writers[id](conn)
def client(IP, port):
""" Process simulating a client
:param IP: Writer to server
:param id: Id for this process.
"""
conn = Channel()
IP(('10.0.0.12', port, conn.writer()))
inp = conn.reader()
outp = inp()
for _ in xrange(10):
outp('Hello from %d ' % port)
msg = inp()
print msg
sleep(0.1)
poison(outp)
def firewall(whitelist, swear_words, addr, port, client_w, monitor_r):
""" Firewall layer for the server. All communication should pass through a
firewall process to reach a server.
:param whitelist: list of (ip, port) doubles of allowed clients.
:param swear_words: List of words not allowed in messages to a server job.
:param addr:
:param port:
:param conn:
"""
# Verify IP/Port whitelist
if (addr, port) in whitelist:
# Setup as node between client and server.
client_chan = Channel()
server_chan = Channel()
server_r = server_chan.reader()
Spawn(do_service(server_chan.writer()))
server_w = server_r()
client_w(client_chan.writer())
client_r = client_chan.reader()
monitor_writer = None;
while True:
g, msg = AltSelect(InputGuard(client_r), InputGuard(monitor_r))
if (g == client_r):
# Poison channels if client swears.
for swear in swear_words:
if swear in msg:
poison(client_w, server_r, client_r, monitor_r)
return
# If no swears, then forward message to server and write response
# back to client.
server_w("[SFW] " + msg)
client_w("[RESP] " + server_r())
if monitor_writer is not None:
monitor_writer(msg)
else:
monitor_writer = msg
else:
poison(client_w)
poison(inp)
if __name__ == '__main__':
swear_words = ["objects", "java", "php", "5"]
whitelist = [("10.0.0.12", 0),
("10.0.0.12", 1),
("10.0.0.12", 2),
("10.0.0.12", 3),
("10.0.0.12", 4),
# ("10.0.0.12", 5),
("10.0.0.12", 6),
("10.0.0.12", 7),
("10.0.0.12", 8),
("10.0.0.12", 9),]
service = Channel()
monitor_access = Channel()
try:
Parallel(server(whitelist, swear_words, service.reader(),
monitor_access.reader()),
[client(service.writer(), id) for id in xrange(10)],
monitor(monitor_access.writer(), conn_to_id("10.0.0.12", 6))
)
except Exception as ex:
if str(ex) == 'Deadlock':
pass # All simulated clients and servers are shut down... time to terminate
else:
raise
shutdown()
