I am trying to write a simple client-server program using python (not python3) and whenever I type a message to send it gives me various errors such as:
File "", line 1
hello my name is darp
^
SyntaxError: invalid syntax
OR
File "", line 1, in
NameError: name 'hello' is not defined
OR
File "", line 1
hello world
^
SyntaxError: unexpected EOF while parsing
Here is the server code:
import socket
def Main():
host = socket.gethostname()
port = 5000
s = socket.socket()
s.bind((host, port))
s.listen(1)
c, addr = s.accept()
print("Connection from: "+str(addr))
while True:
data = c.recv(1024).decode('utf-8')
if not data:
break
print("From connected user: "+data)
data = data.upper()
print("Sending: "+data)
c.send(data.encode('utf-8'))
c.close()
if __name__ == '__main__':
Main()
AND here is the client code
import socket
def Main():
host = socket.gethostname()
port = 5000
s = socket.socket()
s.connect((host, port))
message = input("-> ")
while message != 'q':
s.send(message.encode('utf-8'))
data = s.recv(1024).decode('utf-8')
print("Recieved from server: " + data)
message = input("-> ")
s.close()
if __name__ == '__main__':
Main()
Even though I can create this connection, the problem occurs after I type the message. Any help would be appreciated, thanks!
In Python2 use raw_input instead of input.
You should use the raw_input instead of input since raw_input will capture your input and convert it to the proper type. When using input you should add quotes around the input.
You can check this in the python docs: https://docs.python.org/2/library/functions.html#raw_input
As far as the code is concerned, the only change you need to make here is in server code. Replace c.close() with s.close() as c is a connection variable whereas s is the socket of server according to your code.
I have made your code run, after making the change it runs as expected.I executed it in Python 3.
The server code is here:
import socket
def Main():
host = "127.0.0.1" # supply different hostname instead of socket.gethostname()
port = 5000
s = socket.socket()
s.bind((host, port))
s.listen(1)
c, addr = s.accept()
print("Connection from: "+str(addr))
while True:
data = c.recv(1024).decode('utf-8')
if not data:
break
print("From connected user: "+data)
data = data.upper()
print("Sending: "+data)
c.send(data.encode('utf-8'))
s.close() # it is s which indicates socket
if __name__ == '__main__':
Main()
And the client code is as given by you:
import socket
def Main():
# here, client is using the hostname whereas you need to give different
# hostname for the server (127.0.0.1 for example) otherwise the code doesn't
# work.You can do the reverse as well.
host = socket.gethostname()
port = 5000
s = socket.socket()
s.connect((host, port))
message = input("-> ")
while message != 'q':
s.send(message.encode('utf-8'))
data = s.recv(1024).decode('utf-8')
print("Recieved from server: " + data)
message = input("-> ")
s.close()
if __name__ == '__main__':
Main()
Related
I'm trying to run a client/server script, where the client sends a file to the server and waits for responses until the server sends a stop message.
The problem is: once the connection is established the client starts sending data but until I press CTRL-C the server cannot recreate the file. Only after CTRL-C print "file is fully created" and the file becomes visible, instead, before it's seems to be waiting for something. idk where the problem is. Also tried changing condition on send loop using len(), but doesn't work. Anyone know how to fix it ?
client.py :
import socket # Import socket module
# from threading import Thread
s = socket.socket() # Create a socket object
HOST = "101.xx.x.xxx" # public IP address
PORT = 4243 # Reserve a port for your service.
PDF_PATH = "exam.pdf"
s.connect((HOST, PORT))
def send():
f = open(PDF_PATH, "rb")
while data := f.read(4096):
s.send(data)
f.close()
return
def receive():
while 1:
exercise = s.recv(4096)
if exercise == "stop!":
s.close()
break
f = open(f"{exercise}.txt", "wb")
while data := f.read(4096):
f.write(data)
return
def main():
send()
receive()
if __name__ == "__main__":
main()
server.py :
import socket
from threading import Thread
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
HOST = socket.gethostname()
IP = socket.gethostbyname(HOST)
PORT = 4243
s.bind(('', PORT))
s.listen(5)
def receive_file(conn, i):
f = open(f"exam.pdf", "wb")
while received := conn.recv(4096):
f.write(received)
print("File is fully copied\n")
f.close()
def send_result(conn,i):
while 1:
nbr = str(input("which exercise? "))
if nbr == "stop!":
break
f = open(f"exercise{nbr}.txt", "rb")
conn.send(bytes(f"exercise{nbr}.txt", encoding="utf-8"))
while data := f.read(4096):
conn.send(data)
f.close()
def main():
try:
while 1:
i = 0
conn, addr = s.accept()
print("Got connection from", addr)
# c.send(b"Thank you for connecting")
t = Thread(target=receive_file, args=(conn, i))
t.start()
t.join()
t = Thread(target=send_result, args=(conn, i))
t.start()
t.join()
except KeyboardInterrupt:
print("interrupting \n")
conn.close()
s.close()
if _name_ == '_main_':
main()
conn.recv() in the server won't return '' (no more data) unless the client closes the connection or calls shutdown(SHUT_WR) to indicate sends are complete:
def send():
with open(PDF_PATH, "rb") as f:
while data := f.read(4096):
s.sendall(data)
s.shutdown(socket.SHUT_WR)
An alternative is to design a protocol that sends the length of data before the data so you know when you've received the complete transmission. This would be required if you need to send more than one thing without closing the socket or shutting down sends. You're going to need this to make the receive portion of the server work if you want to send more than one exercise file.
Refer to this answer for an example of sending multiple files over a socket.
I am trying to write a client/server program in python that will accept multiple connections and manage them using threading. The server and client both run, and the client will receive the "welcome" message from the servers "processClient" function, which means the connection is being made and the thread is being started. However, any subsequent receive or send on the connection object after the welcome message fails with an "OSError: [Errno 9] Bad file descriptor" error. I've done some searching on the error, and most problems seem to result from someone trying to use a socket or connection that's been previously closed-which should not be the case here. Does anyone know what could be causing the error? Running python version 3.5.2
Server code:
#!/usr/bin/env python3
import socket
import sys
import os
import datetime
import threading
import random
PORT = 65432 # Port to listen on (non-privileged ports are > 1023)
def processClient(conn, id):
welcome = "Hello, you are client number " + str(id)
welcome = bytes(welcome, 'utf-8')
conn.sendall(welcome)
while True:
data = conn.recv(1024)
print(rpr(data))
time = str(datetime.datetime.now())
arr = bytes(time, 'utf-8')
if data == b'time':
conn.sendall(arr)
elif data == b'':
conn.close()
return
else:
temp = data.decode("utf-8")
temp = temp.upper()
temp = bytes(temp, 'utf-8')
conn.sendall(temp)
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except:
print("unable to create socket connection, shutting down.")
quit()
s.bind(('0.0.0.0', PORT))
s.listen()
sys.stdout.write("Server is running \n")
runningThreads = []
threadID = 0
while True:
conn, addr = s.accept()
with conn:
#conn.setblocking(False)
print('Connected by', addr)
threadID += 1
threadTemp = threading.Thread(target = processClient, args=(conn, threadID))
threadTemp.start()
runningThreads.append(threadTemp)
for t in runningThreads:
if not t.isAlive():
# get results from thtead
t.handled = True
threadID -= 1
else:
t.handled = False
runningThreads = [t for t in runningThreads if not t.handled]
Client code:
#!/usr/bin/env python3
import socket
import sys
import os
import datetime
HOST = 0
while HOST == 0 or HOST == "":
HOST = input("Please enter host IP: ")
PORT = 65432 # The port used by the server
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
s.connect((HOST, PORT))
data = s.recv(1024)
print(repr(data))
while True:
inputString = input("Please input a string: ")
temp = bytes(inputString, 'utf-8')
s.sendall(temp)
if inputString == "":
quit()
data = s.recv(1024)
if data:
print(rpr(data))
for anyone else who stumbles across this: I did finally work out the problem. The server was not waiting on input from the client before it attempts to read data from the connection, which was triggering the error (the error message was particularly unhelpful in diagnosing this issue). I rewrote this to use python selectors rather than threads-selectors includes very handy polling functionality that can be used to "pause" until there is data to be read. I could have built this into the program myself, but why do so when there's already a language feature that does it for you?
I am working on Networking module,making connections with client ans server.
The Server code is as follows :
import socket
def Main():
host = '127.0.0.1'
port = 5000
s = socket.socket()
s.bind((host,port))
s.listen(1)
c, addr = s.connect()
print "Connection from: " + str(addr)
while True:
data = c.recv(1024)
if not data:
break
print "from connected user: " + str(data)
data = str(data).upper()
print "sending: " + str(data)
c.send(data)
c.close()
if __name__ == '__main__':
Main()
The Client code is as follows:
import socket
def Main():
host = '127.0.0.1'
port = 5000
s = socket.socket()
s.connect((host, port))
message = raw_input("-> ")
while message != 'q':
s.send(message)
data = s.recv(1024)
print 'Received from server: ' + str(data)
message = raw_input("-> ")
s.close()
if __name__ == '__main__':
Main()
But not able to execute the program successfully, gives the error address already in use.
Use the command netstat -nlp and find out the above mentioned port in the list.You will find the same port and the corrosponding PID also, either kill that process by kill -9 or you can go to your respective code and change the port number.
Secondly,it's preferrable to use localhost instead of '127.0.0.1'.
And there's an issue in your server code as well, instead of this statement 'c, addr = s.connect()' you need to write this one ' c, addr = s.connect()'.You need too accept the incoming connection and then connect with it.You are missing the acceptance of incoming connection.
I am creating a simple chat in python 3 using socket
here are the code
CLIENT
#!/bin/python
import socket
import threading
import time
tLock = threading.Lock()
poweroff = False
def receving(name, sock):
while not poweroff:
try:
tLock.acquire()
while True:
data, addr = sock.recvfrom(1024)
print (str(data))
except:
pass
finally:
tLock.release()
host = '127.0.0.1'
port = 0
server = ('127.0.0.1', 5000)
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind((host, port))
s.setblocking(0)
rT = threading.Thread(target=receving, args=("RecvThread", s))
rT.start()
alias = input("Username: ")
time.sleep(0.2)
message = input(alias + ">>> ")
while message != 'q':
if message != "":
s.sendto(str(alias + ": " + message).encode('utf-8'), server)
tLock.acquire()
message = input(alias + ">>> ")
tLock.release()
time.sleep(0.2)
poweroff = True
rT.join()
s.close()
SERVER
#!/bin/python
import socket
import time
hostname = '127.0.0.1'
port = 5000
clients = []
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind((hostname, port))
s.setblocking(0)
iQuit = False
print ("Server Started.")
while not iQuit:
try:
data, addr = s.recvfrom(1024)
if addr not in clients:
clients.append(addr)
print (time.ctime(time.time()) + str(addr) + ": :" + str(data))
for client in clients:
s.sendto(data, client)
except:
pass
s.close()
How do i print a string to the server when a user connect?
I have tried to add this string after you have insert the name
s.sendto(str(alias + " Connected").encode('utf-8'), server)
but the output is orrible for me
Another Question:
Why i get something like this when seding a message?
Username: User_A
User_A>>> Hello
User_A>>> How Are you?
b'User:A: Hello'
User_A>>>
b'User_A: How Are you?'
b'User_B: Hi'
Concerning your second question: You are printing binary strings, see here for more information.
Use str(data.decode('utf-8')) instead of str(data) when printing the message on the server or the client.
Concerning the first question: This should work if you send the "Connected" string just after asking for the user name.
The string is decoded the same way as a common message if you include the decode('utf-8') and looks normal to me.
i have to press enter to see if user_B send something to me.
You enforced this behavior by locking out the receiving thread during the input of a message. You have to make up your mind whether you want this or want incoming data to be printed while typing.
You might want to cf. Simultaneous input and output for network based messaging program.
Hi i got a problem with my socket server or the client the problem is i can only send one message from the client to the server then the server stops receiving for some reason i want it to receive more then one.
Server.py
import socket
host = ''
port = 1010
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((host, port))
s.listen(1)
conn, addr = s.accept()
print ("Connection from", addr)
while True:
databytes = conn.recv(1024)
if not databytes:
break
data = databytes.decode('utf-8')
print("Recieved: "+(data))
if data == "dodo":
print("hejhej")
if data == "did":
response = ("Command recived")
conn.sendall(response.encode('utf-8'))
conn.close()
client.py
import socket
host = '127.0.0.1'
port = 1010
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
print("Connected to "+(host)+" on port "+str(port))
initialMessage = input("Send: ")
s.sendall(initialMessage.encode('utf-8'))
while True:
response = input("Send: ")
if response == "exit":
s.sendall(response.encode('utf-8'))
s.close()
There is nothing wrong with your code, but the LOGIC of it is wrong,
in the Client.py file and particularly in this loop:
while True:
response = input("Send: ")
if response == "exit":
s.sendall(response.encode('utf-8'))
This will not send to your Server side anything but string exit because of this:
if response == "exit":
So you are asking your Client.py script to only send anything the user inputs matching the string exit otherwise it will not send.
It will send anything at the beginning before this while loop since you wrote:
initialMessage = input("Send: ")
s.sendall(initialMessage.encode('utf-8'))
But after you are inside that while loop then you locked the s.sendall to only send exit string
You have to clean up your code logic.