I have a server program that can maintain connection with multiple clients. I want to be able to close the socket in response to the message CLOSE by client, or for some other reason. The problem is that the server is stuck on the accept() method and does not care if I close the socket in some other place.
I can use some flag in the main server while, and close the socket after this while, however that means I will have to connect to the server myself after the client request, in order for the while condition to be checked, which smells like really terrible programming.
The code:
import socket
import sys
from thread import *
HOST = '' # Symbolic name meaning all available interfaces
PORT = 9992 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
#Bind socket to local host and port
try:
s.bind((HOST, PORT))
except socket.error , msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
print 'Socket bind complete'
#Start listening on socket
s.listen(10)
print 'Socket now listening'
#Function for handling connections. This will be used to create threads
def clientthread(conn):
#Sending message to connected client
conn.send('Welcome to the server. Type something and hit enter\r\n') #send only takes string
data=''
#infinite loop so that function do not terminate and thread do not end.
while True:
#Receiving from client
data += conn.recv(1024)
print data
if data == 'CLOSE':
global s
conn.sendall('You have requested to destroy the connection...')
conn.close()
s.close()
return
if data.find('\n') != -1:
conn.sendall('OK...' + data + '\r\n')
data=''
#now keep talking with the client
while 1:
#wait to accept a connection - blocking call
try:
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
#start new thread takes 1st argument as a function name to be run, second is the tuple of arguments to the function.
start_new_thread(clientthread ,(conn,))
except:
print 'socket issue sorry'
break
Related
The below code does not work, when I keep both socket server and client code in the same script file where I run server in the main thread and the client in a separate thread using start_new_thread
import socket, sys
from thread import *
host = socket.gethostname()
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
s.bind((host, 8888))
except socket.error as msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
s.listen(10)
def clientthread(conn):
conn.send('Welcome to the server. Type something and hit enter\n')
while True:
data = conn.recv(1024)
reply = 'OK...' + data
if not data:
break
conn.sendall(reply)
conn.close()
while 1:
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
start_new_thread(clientthread ,(conn,))
s.close()
If you bind() to your gethostname(), you also have to connect to that interface from the client, even if it is on the same computer. "localhost" or "127.0.0.1" will not work. If you want them to work, either bind() to them directly, or bind to everything ("0.0.0.0" or just an empty string, "").
Low-budget test code:
from _thread import *
import socket,time
def client():
print("Thread starts")
time.sleep(1)
print("Thread connects")
sock=socket.create_connection((socket.gethostname(),8888))
#sock=socket.create_connection(("localhost",8888))
print("Thread after connect")
sock.sendall(b"Hello from client")
sock.close()
print("Thread ends")
serv=socket.socket()
serv.bind((socket.gethostname(),8888))
#serv.bind(("localhost",8888))
#serv.bind(("0.0.0.0",8888))
#serv.bind(("",8888))
serv.listen(10)
start_new_thread(client,())
print("Before accept")
s,c=serv.accept()
print("After accept "+c[0])
print("Message: "+s.recv(1024).decode("ASCII"))
s.close()
serv.close()
Feel free to experiment with testing the various sock+bind combinations.
Here is a snippet from a specific server program I a working on.
Requirements:
I want the program to initiate a socket on port defined by ownport variable and listen on that port for incoming TCP messages.
Based on the specific value I receive on the socket from remote hosts, the server has to initiate functions func1() or func2() [Example: if the value is JOIN, then execute func1 and if it is UPDATE execute func2]
These actions are mutually exclusive and multiple clients may be connected to the server at the same time and might be sending requests.
How can I effectively multithread this so that the server constantly listen on the port and initiate the functions based on the incoming requests in realtime?
# Creating a socket
try:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error, msg:
print 'Failed to create socket. Error code: ' + str(msg[0]) + ' , Error message : ' + msg[1]
sys.exit();
print "Socket created!"
#Binding the socket to specified ports
try:
sock.bind((ownhost, ownport))
except socket.error , msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
print 'Socket bind complete'
# Listening for incoming requests
sock.listen(10)
print 'Socket now listening'
conn, addr = sock.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
# Handling the incoming requests received
req = conn.recv(1024)
reqpro = req.split('|')
# If the request is a join request
if reqpro[0] == "JOIN":
func1(reqpro, arg2)
elif (reqpro[0] == 'UPDATE') and (reqpro[1] == 'PRED'):
func2(reqpro,arg2)
else:
print "invalid request type"
sys.exit()
I'm stuck on this socket communication, I've looked everywhere but I haven't found an answer yet.
THE PROBLEM: I can only send 1 message from the client before it either gives me an error or ends the script.
I need to be able to send multiple messages to the server.
The server side (shown below) should be fine:
# Echo server program
import socket
import time
import os
#-----------------------------------------------------------------------------------------------------------------------
today = time.strftime('%Y.%m.%d')
logFileName = "log - " + today + ".txt"
HOST = '10.0.0.16'
PORT = 8080 # Reserve a port for your service
BUFFER_SIZE = 1024
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # Create a socket object
s.bind((HOST, PORT)) # Bind to the port
def print_write(text):
log.write(time.strftime("%H:%M:%S") + " | " + text)
log.write("\n")
print text
#-----------------------------------------------------------------------------------------------------------------------
if os.path.isfile(logFileName) is True:
log = open(logFileName, 'a+')
print_write("[SERVER] Log for " + today + " already exists.")
print_write("[SERVER] Starting comms")
else:
print "[SERVER] Log doesn't exist"
log = open(logFileName, 'a+') # Create file -> log - %date%.txt
print_write("[SERVER] Log created")
while True:
s.listen(1)
conn, addr = s.accept()
data = conn.recv(BUFFER_SIZE)
if data == "Comms Shutdown":
print_write("------ REMOTE SHUTDOWN ------")
conn.close()
raise SystemExit
else:
print_write("[COMMS] " + str(addr) + " says: " + data)
log.close()
Sorry if it's very messy and confusing but i don't have much time to finish this project, if you have any question just ask.
For the client side I don't have much but here, I'll give you this:
import socket
HOST = '10.0.0.16' # The remote host
PORT = 8080 # The same port as used by the server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
while True:
msg = raw_input()
s.sendall(msg)
print msg
I know it doesn't work, it's just to give you an idea of what I need.
Thank you in advance.
The problem is, that you only read the first message from each open connection before moving on to the next. The accept() methods waits for a new connection and gives you the information needed when a new one comes in. the recv() method on the other hand, receives data from a existing connection and waits if there is none. If you want to receive multiple messages from a single client, you can just wait for the first connection and then wait for data with recv(). This could look like this:
s.listen(1)
conn, addr = s.accept()
while True:
data = conn.recv(BUFFER_SIZE)
if data == "Comms Shutdown":
print_write("------ REMOTE SHUTDOWN ------")
conn.close()
raise SystemExit
else:
print_write("[COMMS] " + str(addr) + " says: " + data)
If you want to be able to also manage multiple clients, you will have to create a thread for each one from a while loop waiting for new connections. This is a bit more complicated:
def client_handler(conn):
while True:
data = conn.recv(BUFFER_SIZE)
if data == "Comms Shutdown":
print_write("------ REMOTE SHUTDOWN ------")
conn.close()
raise SystemExit
# this will kill the server (remove the line above if you don't want that)
else:
print_write("[COMMS] " + str(addr) + " says: " + data)
while True:
s.listen(1)
conn, addr = s.accept()
recv_thread = threading.Thread(target=client_handler, args=(conn, ))
recv_thread.start()
All this code is untested. Be aware, that I omitted the logging part and the socket creation part as well as all imports.
I attempted to find an answer for this, but most examples out there are for purely echo base Socket Servers.
Basically I have the following code:
import socket
import sys
from thread import *
HOST = '' # Symbolic name meaning all available interfaces
PORT = 8888 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
#Bind socket to local host and port
try:
s.bind((HOST, PORT))
except socket.error as msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
print 'Socket bind complete'
#Start listening on socket
s.listen(10)
print 'Socket now listening'
#Function for handling connections. This will be used to create threads
def clientthread(conn):
#Sending message to connected client
conn.send('Welcome to the server. Type something and hit enter\n') #send only takes string
#infinite loop so that function do not terminate and thread do not end.
while True:
#Receiving from client
data = conn.recv(1024)
if data == "hello":
reply = 'OK...Hello back to you'
else:
reply = '01:OK - ' + data
if not data:
break
conn.sendall(reply)
#came out of loop
conn.close()
#now keep talking with the client
while 1:
#wait to accept a connection - blocking call
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
#start new thread takes 1st argument as a function name to be run, second is the tuple of arguments to the function.
start_new_thread(clientthread ,(conn,))
s.close()
Everything works great until I try to use a conditional statement. I am very new to python and I am using this as a way to learn it a little better, but when the following line runs it skips the if each time.
#Receiving from client
data = conn.recv(1024)
if data == "hello":
reply = 'Why hello there!'
else:
reply = '01:OK - ' + data
if not data:
break
conn.sendall(reply)
From the telnet client I am connecting to it just echos everything I send it including the 'hello' I send it rather than the phrase.
I have a feeling that it is something simple, but I am not sure the format of the data variable.
Very close!
Telnet will send whatever EOL delimiter you gave it, along with the text. So if you type "data" and press enter, data is actually something like hello\r\n.
You can effectively ignore this whitespace by doing something like changing
data = conn.recv(1024)
to
data = conn.recv(1024).strip()
And you should be good to go.
EDIT:
As noted in the comments, the network may split up the message into multiple packets. To work around this, you can use use the socket.makefile() method and get a file-like object and then use readline() which will block until a complete line is available. For example, changing clientthread to:
def clientthread(conn):
#Sending message to connected client
conn.send('Welcome to the server. Type something and hit enter\n') #send only takes string
sfh = conn.makefile("r+b", bufsize=0)
#infinite loop so that function do not terminate and thread do not end.
while True:
#Receiving from client
data = sfh.readline().strip()
if data == "hello":
reply = 'OK...Hello back to you'
else:
reply = '01:OK - ' + data
if not data:
break
conn.sendall(reply)
#came out of loop
conn.close()
== PYTHON ==
Socket created
Socket bind complete
Socket now listening
Connected with 192.168.1.10:42749
== TELNET ==
$ telnet 192.168.1.106 8888
Trying 192.168.1.106...
Connected to 192.168.1.106.
Escape character is '^]'.
Welcome to the server. Type something and hit enter
hello
OK...Hello back to you
So I'm starting to work on a kind of Internet of Things project and the first issue I'm stumbling upon is having trouble in setting up a basic server. Using this guide, to do some initial tests, here is the code being used:
'''
Simple socket server using threads
'''
import socket
import sys
HOST = '' # Symbolic name, meaning all available interfaces
PORT = 8888 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
#Bind socket to local host and port
try:
s.bind((HOST, PORT))
except socket.error as msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
print 'Socket bind complete'
#Start listening on socket
s.listen(10)
print 'Socket now listening'
#now keep talking with the client
while 1:
#wait to accept a connection - blocking call
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
s.close()
I can set the server up and it will listen on socket, but when i try to connect with telnet, it times out. Since I'm on a network in my college, could this be the reason why things aren't going through? I remember doing something like this in C a while back and it seemed to work then...
The code works, but doesn't send/receive from the client. The following modest change makes the server send beer tasty to any lucky clients.
source
'''
Simple socket server using threads
'''
import socket
import sys
HOST = '' # Symbolic name, meaning all available interfaces
PORT = 8888 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
#Bind socket to local host and port
try:
s.bind((HOST, PORT))
except socket.error as msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()
print 'Socket bind complete'
#Start listening on socket
s.listen(10)
print 'Socket now listening'
#now keep talking with the client
while 1:
#wait to accept a connection - blocking call
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])
conn.send('beer tasty\n') # <==
conn.close()
s.close()
test with Netcat in Linux. (Telnet also should work)
test
$ echo beer | nc -q1 localhost 8888
Connected with 127.0.0.1:37484
beer tasty