First off I'm want to learn socket/network programming with python
so a lot of what I ask is newbie related.
I have written a test socket server that runs as a daemon.
It listens on two sockets (say at ports 8000 and 9000) so that I can
telnet over from another machine and get process info (ps type of info),
one one port and control the server on the other port.
What I want is to have the daemon run thread (A) which listens
on port 8000, and then runs another thread (B) which listens 9000.
Thread A monitors whether thread B is alive with a
thread_B_.isSet() call.
If thread B has terminated then thread A can exit when user tells
it to, otherwise not.
Thread B will terminate when user tells it to exit.
I can start the daemon and connect to both ports just fine.
If I leave the connections on using telnet for example, the connections
keep working (stay alive). This part works.
But I also want to be able to disconnect the telnet sessions,
but leave the daemon server still listening on both ports so I can
reconnect to both ports later.
If I disconnect and try to reconnect within about 10secs it works fine.
However if I stay disconnected from more than a minute then
I cannot reconnect later. It seems as if the the server is not
listening anymore....although the threads are still running
i.e. the daemon is up.
The message from telnet is:
>>telnet: connect to address xxx.xxx.xxx.xxx: Connection refused
Perhaps I do not understand the function of the following:
socket.setdefaulttimeout(15)
socket.settimeout(15.0)
What is the difference between these??
Yes I have read the python docs
- setdefaulttimeout(timeout) Set the default timeout in floating
seconds for new socket objects.
whereas:
- settimeout(value): Set a timeout on blocking socket operations.
So what this means to me is that with setdefaulttimeout one can set
a global timeout for new sockets, wheres with settimeout one can fine tune
it after a socket has been created. This is probably all wrong.
Any ideas as to what is causing the server to stop listening after I disconnect
for a long period of time.
Also does one have to do a socket.shutdown() before one does a socket.close??
How should a server disconnect a client but keep listening for subsequent
connections from other clients?
I have included a summary of important code below.
Let me know if should provide more or different info.
Thanks a lot in advance.
Pete
-------------------------------------
The program basically works as below:
-------------------------------------
(1) become a daemon
(2) call server function which does the following (summarized):
import socket
...
HOST = ''
socket.setdefaulttimeout(15)
try:
sa = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sa.bind((HOST, AdminPort))
sa.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sa.settimeout(15.0)
sa.listen(1)
except:
## exit on failure
## run 2nd socket handler as thread
# create an event to signal the completion of client handler thread
client_handler_complete=threading.Event()
client_handler_complete.clear()
server_handler_thread = threading.Thread (None, ClientHandler, None, \
(StateValues, client_handler_complete))
try:
server_handler_thread.start()
except:
## exit on failure
while 1: ## wait for a connection
try:
#...waiting for connection
(client, address)=sa.accept()
except sa.timeout:
#...waiting for connection timeout
continue
except:
continue ## for now ignore this!
#...someone's connecting, so check if ipaddress is allowed
remote = str(address[0])
if Allowed_Hosts.has_key(remote):
hostname = Allowed_Hosts[remote]
Message = '%s connection accepted from: %s (%s:%s))' % \
(FUNCNAME, hostname, address[0], address[1])
log_message(StateValues, Message, 1)
else:
client.close()
Message = '%s connection rejected from: %s' %
(FUNCNAME, address)
log_message(StateValues, Message, 1)
continue
socketfile = client.makefile()
while 1: ## wait for user input
data = ''
data=read_data(socketfile)
if not data or data == 'CR':
continue
else:
Message = '%s input received: %s' % (FUNCNAME,
data)
log_debug_message(StateValues, Message)
if data == 'q':
##disconnect client but keep waiting for connections
...
client.close()
elif data == 'x':
##disconnect client and shutdown server
...
client.close()
socketfile.close()
sys.exit(0)
## wait for user input
## end wait for a connection
(3) the thread which handles the second socket is coded like that above.
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