I'm reading two programs in Python 2.7.10 with client and server. How can I modify these programs in order to send a message from client to server?
server.py:
#!/usr/bin/python # This is server.py file
import socket # Import socket module
s = socket.socket() # Create a socket object
host = socket.gethostname() # Get local machine name
port = 12345 # Reserve a port for your service.
s.bind((host, port)) # Bind to the port
s.listen(5) # Now wait for client connection.
while True:
c, addr = s.accept() # Establish connection with client.
print 'Got connection from', addr
c.send('Thank you for connecting')
c.close() # Close the connection
client.py:
#!/usr/bin/python # This is client.py file
import socket # Import socket module
s = socket.socket() # Create a socket object
host = socket.gethostname() # Get local machine name
port = 80 # Reserve a port for your service.
s.connect((host, port))
print s.recv(1024)
s.close # Close the socket when done
TCP sockets are bi-directional. So, after connection, there is no difference between server and client, you only have two ends of a stream:
import socket # Import socket module
s = socket.socket() # Create a socket object
s.bind(('0.0.0.0', 12345)) # Bind to the port
s.listen(5) # Now wait for client connection.
while True:
c, addr = s.accept() # Establish connection with client.
print 'Got connection from', addr
print c.recv(1024)
c.close() # Close the connection
and the client:
import socket # Import socket module
s = socket.socket() # Create a socket object
s.connect(('localhost', 12345))
s.sendall('Here I am!')
s.close() # Close the socket when done
The above answer throws an error: TypeError: a bytes-like object is required, not 'str'
However, the following code worked for me:
server.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
port = 3125
s.bind(('0.0.0.0', port))
print ('Socket binded to port 3125')
s.listen(3)
print ('socket is listening')
while True:
c, addr = s.accept()
print ('Got connection from ', addr)
print (c.recv(1024))
c.close()
client.py:
import socket
s = socket.socket()
port = 3125
s.connect(('localhost', port))
z = 'Your string'
s.sendall(z.encode())
s.close()
Related
I'm trying a simple send/receiver example on my local machine using TCP. The goal is to open a TCP server and send some data. My setup is Python3.6 on Pycharm IDE. I have enabled parallel run of the sender and receiver scripts.
Here is the Server script:
import socket
import sys
# Create a TCP/IP socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# Bind the socket to the port
server_address = ('localhost', 5005)
print(sys.stderr, 'starting up on %s port %s' % server_address)
sock.bind(server_address)
# Listen for incoming connections
sock.listen(1)
while True:
# Wait for a connection
print(sys.stderr, 'waiting for a connection')
connection, client_address = sock.accept()
try:
print(sys.stderr, 'connection from', client_address)
# Receive the data in small chunks and retransmit it
while True:
data = connection.recv(16)
print(sys.stderr, 'received "%s"' % data)
if data:
print(sys.stderr, 'sending data back to the client')
connection.sendall(data)
else:
print(sys.stderr, 'no more data from', client_address)
break
finally:
# Clean up the connection
connection.close()
And here is the client script:
import socket
TCP_IP = 'localhost'
TCP_PORT = 5005
BUFFER_SIZE = 1024
MESSAGE = "Hello, World!"
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((TCP_IP, TCP_PORT))
s.send(MESSAGE.encode('utf-8'))
I verified that both scripts are running and I've used the debugger to parse each line on the sender side. I get no errors but I also don't see that the server receives anything.
EDIT:
I have used an example code from this page
Server:
#!/usr/bin/env python3
import socket
HOST = '127.0.0.1' # Standard loopback interface address (localhost) PORT = 65432 # Port to listen on (non-privileged ports are > 1023)
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
s.bind((HOST, PORT))
s.listen()
conn, addr = s.accept()
with conn:
print('Connected by', addr)
while True:
data = conn.recv(1024)
if not data:
break
conn.sendall(data + b' from server')
Client:
#!/usr/bin/env python3
import socket
HOST = '127.0.0.1' # The server's hostname or IP address
PORT = 65432 # The port used by the server
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
s.connect((HOST, PORT))
s.sendall(b'Hello, world')
data = s.recv(1024)
print('Received', repr(data))
And I get the expected result:
Received b'Hello, world from server'
Hmm, the client scripts ends immediately after sending its data... This is at least dangerous! Race conditions could cause the connection to be destroyed before anything has been correctly received by the peer. The robust way would be to use a graceful shutdown client side:
...
s.send(MESSAGE.encode('utf-8'))
s.shutdown(socket.SHUT_WR) # tell peer we have nothing more to send
while True:
data = s.recv(256)
if len(data) == 0: # but keep on until peer closes or shutdowns its side
break
After that, I could test that your server script could correctly receive and send back the message:
<idlelib.run.StdOutputFile object at 0x0000021279F1CBB0> starting up on localhost port 5005
<idlelib.run.StdOutputFile object at 0x0000021279F1CBB0> waiting for a connection
<idlelib.run.StdOutputFile object at 0x0000021279F1CBB0> connection from ('127.0.0.1', 62511)
<idlelib.run.StdOutputFile object at 0x0000021279F1CBB0> received "b'Hello, World!'"
<idlelib.run.StdOutputFile object at 0x0000021279F1CBB0> sending data back to the client
<idlelib.run.StdOutputFile object at 0x0000021279F1CBB0> received "b''"
<idlelib.run.StdOutputFile object at 0x0000021279F1CBB0> no more data from ('127.0.0.1', 62511)
<idlelib.run.StdOutputFile object at 0x0000021279F1CBB0> waiting for a connection
Note : This problem has been completely solved, as was am running client.py before server.py
Just got started with socket programming, I have created the below code and expecting to print some byte message, but it isn't doing that.
I just want to make the message available for any person on any
machine. But it's refusing by the machine to do that.
Here is my code:
server.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
port = 12048
s.bind((socket.gethostname(), port))
s.listen()
while True:
c, addr = s.accept()
print("Got connection from", addr)
c.send(bytes("Thank you", "utf-8"))
client.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
port = 12048
s.connect(('192.168.0.1', port))
msg = s.recv(1024)
print(msg.decode("utf-8"))
Some images to better explain my errors:
Any help would be appreciated!!!
It looks like in the server.py script you use s.bind((socket.gethostname(), port)) where socket.gethostname() is a hostname, but in the client.py script you use s.connect(('192.168.0.1', port)) where '192.168.0.1' is the hostname you are trying to connect.
I think there you have socket.gethostname() != '192.168.0.1' and that's the problem.
Also, you can bind to all available IP addresses on the host using this solution Python socket bind to any IP?
Let's use listen_ip = socket.gethostbyname(socket.gethostname()) for connection since socket.gethostname() may return hostname instead of IP and it will not be solved by python dns resolver in local network if it was local name, not DNS.
and use it later as s.bind((listen_ip, port)) and s.connect((listen_ip, port))
After some debugging I've got a working solution for you
There are the scripts required.
server.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
host = socket.gethostbyname(socket.gethostname())
port = 12_048
s.bind((host, port))
s.listen()
print("Server listening # {}:{}".format(host, port))
while True:
c, addr = s.accept()
print("Got connection from", addr)
c.send(bytes("Thank you", "utf-8"))
client.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
host = '192.168.1.162' # The IP printed by the server must be set here
# or we can set it using env variable named SERVER_IP
if 'SERVER_IP' in os.environ:
host = os.environ['SERVER_IP']
port = 12048
print("Connecting to {}:{}".format(host, port))
s.connect((host, port))
msg = s.recv(1024)
print(msg.decode("utf-8"))
In a chat conversation we concluded that the hardcoded IP in the question is not the correct one. This solution does have the IP he needed but it will be different in each case. Remeber that server.py needs to be launched first, and when you see the printed Server listening # IP:12048, write that IP in client.py and launch it. Client does need to be launched after seeing that line even if you already know the IP, as the server needs some time to be ready and the client will crash if it tries to connect to the server while it is not ready.
server.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
host = socket.gethostbyname(socket.gethostname())
port = 12048
s.bind((host, port))
s.listen()
print("Server listening # {}:{}".format(host, port))
while True:
c, addr = s.accept()
print("Got connection from", addr)
c.send(bytes("Thank you", "utf-8"))
client.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
host = '192.168.1.162' # The IP printed by the server must be set here
port = 12048
print("Connecting to {}:{}".format(host, port))
s.connect((host, port))
msg = s.recv(1024)
print(msg.decode("utf-8"))
A simple demo of socket programming in python:
server.py
import socket
host = '127.0.0.1'
port = 8000
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((host, port))
s.listen(1)
conn, addr = s.accept()
while True:
data = conn.recv(1024)
print 'Received:', data
if not data:
break
conn.sendall(data)
print 'Sent:', data
conn.close()
client.py
import socket
host = '127.0.0.1'
port = 8000
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
s.sendall('Hel')
s.sendall('lo world!')
print 'Received:', s.recv(1024)
s.close()
Now code work well. However, the client may not know if server will always send back every time. I tried symmetric code of while-loop in server.py
client_2.py
import socket
host = '127.0.0.1'
port = 8000
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
s.sendall('Hel')
s.sendall('lo world!')
while True:
data = s.recv(1024)
if not data:
break
print 'Received:', data
s.close()
This code will block at
data = s.recv(1024)
But in server.py, if no data received, it will be blank string, and break from while-loop
Why it does not work for client? How can I do for same functionality without using timeout?
You can set a socket to non-blocking operation via socket.setblocking(false), which is equivalent to socket.settimeout(0). Solving this "without using timeout" is impossible.
I have a basic server and client that prints a message on the server when a client connects, and then prints a message on the client saying "Thanks for connecting." But when I try to run the server again(after closing it), I get "error: Only one usage of each socket address is normally permitted"(Not exact). And when I change the port again it works.
#Server
import socket
s = socket.socket()
host = socket.gethostname()
port = 12345
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()
.
#Client
import socket
s = socket.socket()
host = socket.gethostname()
port = 12345
s.connect((host, port))
print s.recv(1024)
s.close
If I change the last two lines of code for the server to
break
c.close()
it works but closes the server.
How can I keep the server up after the client disconnects without having to change the port each time?
You want to set the socket option SO_REUSEADDR:
Example:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
I like to have one port that first use for connect to another server and after that this port use to be a server and another clients connect to it.
I used python socket for client now I want to use it for server socket.
my code :
#!/usr/bin/python # This is server.py file
import socket # Import socket module
s = socket.socket() # Create a socket object
host = socket.gethostname() # Get local machine name
port = 12349
portt = 12341 # Reserve a port for your service.
s.bind((host, portt)) # Bind to the port
s.connect((host, port))
s.listen(5) # Now wait for client connection.
c, addr = s.accept() # Establish connection with client.
print c
print 'Got connection from', addr
print s.recv(1024)
s.close
and the output is
Traceback (most recent call last):
File "client.py", line 12, in <module>
s.listen(5) # Now wait for client connection.
File "/usr/lib/python2.7/socket.py", line 224, in meth
return getattr(self._sock,name)(*args)
socket.error: [Errno 22] Invalid argument
How can I do that.
thank you for your answers!
Not sure what you are trying to do here. Seems to me that you are mixing client and server code in the same app.
For reference, you can create a simple echo server like this:
import socket
HOST = ''
PORT = 12349
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(5)
conn, addr = s.accept()
print 'Connected by', addr
while 1:
data = conn.recv(1024)
if not data: break
conn.sendall(data)
conn.close()
And a simple echo client like this:
import socket
HOST = 'localhost'
PORT = 12349
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
s.sendall('Hello, world')
data = s.recv(1024)
s.close()
print 'Received', repr(data)