I'm trying to write a program that gets IP adress as an input inside a while loop and makes a TCP connection with it.
Here is an example:
import socket
s1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while True:
adress=input('Enter the IP:')
s1.connect((adress, 8000))
message=input('Enter the message:')
s1.send(message.encode())
s1.close()
Server:
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('', 8000))
s.listen(5)
print('ready')
while True:
c, addr = s.accept()
recieved_message= c.recv(1024)
print(recieved_message.decode())
c.close()
It successfully makes the first connection and server recieves the first message but when I try to connect it again by inputting the same IP adress I get this error:
[WinError 10038] an operation was attempted on something that is not a socket
I removed s1.close() to outside of the while loop to fix thix but this time I got this error:
[WinError 10056] A connection attempt targeted an already connected socket
I can't find way to solve this. How can I fix this problem?
The first error is from reusing a closed socket, and the second error is from reconnecting to an already connected socket.
Put the s1 = line inside the while loop in the client to create a new socket for each connection.
import socket
while True:
s1 = socket.socket()
address = input('Enter the IP:')
s1.connect((address, 8000))
message = input('Enter the message:')
s1.send(message.encode())
s1.close()
Related
I have the following client/server python code. The print line from the server where i used f-string interpolation does not show anything when the code is executed and I would like to know why?
I followed this tutorial and on their end the print line shows result.
tutorial: https://www.tutorialspoint.com/python/python_networking.htm
line: Got connection from ('127.0.0.1', 48437)
my server code:
#!/usr/bin/python
# Server.py
# Import socket module
import socket
# Create a socket object
s = socket.socket()
# Get local machine name
host = socket.gethostname()
# Reserve a port number for the socket service
port = 22226
# Bind the host address and the port number
s.bind((host, port))
# Listens for the client connections made for the socket.
# The argument shows maximum number of queued connections and it is 1 at minimum
s.listen(5)
while True:
# Establish connection with client.
c, addr = s.accept()
print(f"Got connection from {addr}")
c.send(b'Thank you for connecting')
c.close() # Close the connection
my client code:
#!/usr/bin/python
# client.py
# Import socket module
import socket
# Create a socket object
s = socket.socket()
# Get local machine name
host = socket.gethostname()
# Reserve a port number for the socket service
port = 22226
# Connect the host address and the port number
s.connect((host, port))
# Read at most 1024 bytes
print(s.recv(1024))
s.close() # Close the socket when done
My socket sends the first message but nothing afterward.
The output in the server:
What do you want to send?
lol
The client receives:
From localhost got message:
lol
And then it doesn't want to send anything else.
I don't get the what do you want to send printed anymore.
My code:
server.py file:
#!/usr/bin/python3
import socket
# create a socket object
serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# get local machine name
host = socket.gethostname()
print ("got host name:", host)
port = 9996
print("connecting on port:", port)
# bind to the port
serversocket.bind((host, port))
print("binding host and port")
# queue up to 5 requests
serversocket.listen(5)
print("Waiting for connection")
while True:
clientsocket, addr = serversocket.accept()
msg = input("what do you want to send?\n")
clientsocket.send(msg.encode('ascii'))
client.py file:
#!/usr/bin/python3
import socket # create a socket object
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # get local machine
# name
host = socket.gethostname()
port = 9996 # connection to hostname on the port.
s.connect((host, port)) # Receive no more than 1024 bytes
while True:
msg = s.recv(1024)
print(msg.decode("ascii"))
The client only connects once (OK) but the server waits for an incoming connection every start of the while loop.
Since there are no more connection requests by a client, the server will freeze on the second iteration.
If you just want to handle a single client, move clientsocket, addr = serversocket.accept() before the while loop. If you want to handle multiple clients, the standard way is to have the server accept connections inside the while loop and spawn a thread for each client.
You can also use coroutines, but that may be a bit overkill if you are just starting out.
I am a beginner in python socket programming. My question is, I have a TCP server in listen mode at that time client will send data to the server. But when my TCP server is unavailable at that I want a client to go and check for connection every time (something like try exception method with while loop).
I have tried tricks but that didn't work out, it gives o/p like connection refused when my TCP server is unavailable. Below is my code help me with same.
# client.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
host = socket.gethostname()
port = 2195
s.connect((host, 2195))
while 1:
try:
print "Try loop"
s.sendall("Welcome to Python\r\n")
print "Try loop2"
time.sleep(5)
except:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
s.close()
I have tried many solutions but below code works for me.
client.py
import socket
import time
while True:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR,1)
host = socket.gethostname()
port = 2195
try:
s.connect((host , port))
s.sendall("Welcome to Python\r\n")
except:
print "Error"
time.sleep(5)
s.close()
How do I get a response from the server?
Client side:
#CLIENT
import socket
import time
host = "localhost"
port = 5454
data_c = input()
c = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
c.sendto(bytes(data_c, 'utf-8'),(host,port))
print( data_c )
print( c.recv(1024).decode('utf-8'))
SERVER side:
#SERVER
import socket
import time
host = "localhost"
port = 5454
data_s = "ACKNOWLEDGMENT"
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind((host, port))
print(s.recv(1024).decode('utf-8'))
I can send a message from the server that the client will receive, but can not seem to get communication (like an ACK.) to make it back to the server.
(yes UDP is not a good way to be doing this i'm pretty sure, but that was a specific for the project)
for question 1: to send the ACK, you could replicate what you have in the reverse direction.
Since UDP is connection-less you don't know beforehand you receive a packet where the packet will come from, so you have to use recvfrom to get both the packet and the peer (address/port) the packet came from. Then you have to use that address to send data back.
What you're doing now in your client (but what really looks like the server) in the loop is send the same data over and over to itself. Instead in the loop you should receive packets using the previously mentions recvfrom then send replies to the peer you received the packet from.
So something like the following pseudo code
while True:
peer = recvfrom(...)
sendto(..., peer)
After many attempts to get a simple acknowledgment reply from my server this did it.
Beyond literally starting completely over each round, the time.sleep(.1) function was the only missing key. It allowed the server and client both time to close the current socket connection so that there was not an error of trying to bind multiple bodies to a single location or something.
OSError: [WinError 10048] Only one usage of each socket address (protocol/network address/port) is normally permitted
Working result:
#SERVER
import socket
import time
host = "localhost"
port = 5454
data_s = "ACKNOWLEDGMENT"
while 1:
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind((host, port))
received = print("Client: " + s.recv(1024).decode('utf-8')) #waiting to receive
s.close
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
time.sleep(.1)
s.sendto(bytes(data_s, 'utf-8'),(host,port)) #sending acknowledgment
print("Server: " + data_s)
s.close # close out so that nothing sketchy happens
time.sleep(.1) # the delay keeps the binding from happening to quickly
Server Command Window:
>>>
Client: hello
Server: ACKNOWLEDGMENT
Client:
#CLIENT
import socket
import time
host = "localhost"
port = 5454
c = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
while 1:
data_c = input("Client: ")
c = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
c.sendto(bytes(data_c, 'utf-8'),(host,port)) #send message
c.close
# time.sleep()
c = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
c.bind((host, port))
print("Server: " + c.recv(1024).decode('utf-8')) # waiting for acknowledgment
c.close
c = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
time.sleep(.1)
Client Command Window:
>>>
Client: hello
Client: hello
Server: ACKNOWLEDGMENT
I did finally remove the redundant input("Client: ") there at the top.
A special thanks #JoachimPileborg for helping, but I have to give it to the little guy just because it was the path I ended up taking.
I learned sockets in python. When I tried to programming sockets script in one computer, it worked, but when I tried to programming sockets script with two different computers and open socket with connection, it didn't work.
One computer(the server):
import socket
s = socket.socket()
host = socket.gethostname()
port = 1234
s.bind((host, port))
s.listen(5)
while True:
c, addr = s.accept()
print 'Got connection from', addr
c.send('Thank you for connecting')
c.close()
Second computer(the client):
import socket
s = socket.socket()
host = raw_input("The ip you want to connect to: ")
port = 1234
s.connect((host, port))
print s.recv(1024)
Error:
socket.error: [Errno 10061]
What is the problem in the scripts? Why it doesn't work?
Errno 10061:
It means the server you are trying to connect to is not waiting for one.
Make sure you have the port number open.
Try killing all python processes and start server again.
Update
Instead of
host = socket.gethostname()
use
host = ""