错误 111：仅在 python IDLE 中拒绝连接

Question

When I try to execute Python server socket program and client socket program (both running in same linux machine) in Linux terminal I don't get any error , server accepts connection and sends data to client successfully.

But when I execute the same programs in python IDLE I get " [Errno 111] Connection refused " error.

What is the difference in both execution?

I'm using serversock.bind(('',port#)) in server and in client i'm using clientsock.connect(('localhost',port#))

Server.py

import socket

serversock = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
host = ''
print host
port = 5800
serversock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
serversock.bind((host,port))
serversock.listen(2)

try:
    while True:
        csock,addr = serversock.accept()
        print 'Recieved address from %s '% str(addr)
        csock.send('hello')
        csock.close()

except Exception,e:
    print e

client.py

import socket

 try:
   c = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
   host = 'localhost'
   port = 5800
   c.connect((host,port))
   data = c.recv(1024)
   print data

except Exception,e:
   print e

finally:
   c.close()

Answer 1

Server side you must use:

serversock.bind(('',port#))    # binds to port
serversock.listen(5)           # actually listen to port and allow 5 incoming calls
conv = serversock.accept()     # accept first incoming call

The connection will only be accepted after the listen call, before it, you have only bound a socket, but have not declared that you were ready to accept incoming calls, so they are refused.

---

With added code, another possible error cause is that you close connection (server side) immediately after sending data. That is bad: the close condition can destroy the socket before the data has actually been sent.

You should use a graceful shutdown :

• server side:

   csock.send('hello') csock.shutdown(socket.SHUT_WR) # shutdown the socket csock.read() # wait the close from peer csock.close()

• client side: you can leave the code as is in your use case you do not send anything to server, so when the client has finished reading it can safely close the socket

Anyway you should close serversock when everything is finished

try:
    ...
except ...:
    ...
finally:
    serversock.close()