Python client disconnect if server closes connection

Question

I have server and client code in python in which client sends a request message to server and wait for the response. I have the server code to close the connection when the client doesn't send a proper request. When the server closes the request, the client still is listening forever for the response.

Below is the code

server.py

s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
s.bind((host, port))

s.listen(1)

while True:

  c, addr = s.accept()

  # Receive request
  data = c.recv(1024)
  if data != 'something'
    c.close()
  else
    c.sendall("message"+"End")
    c.close()
s.close()

Client.py

End='End'
def recv_end(the_socket):
  # Snippet from http://code.activestate.com/recipes/408859-socketrecv-three-ways-to-turn-it-into-recvall/
  total_data=[];data=''
  while True:
    data=the_socket.recv(8192)
    if End in data:
      total_data.append(data[:data.find(End)])
      break
    total_data.append(data)
    if len(total_data)>1:
      #check if end_of_data was split
      last_pair=total_data[-2]+total_data[-1]
      if End in last_pair:
        total_data[-2]=last_pair[:last_pair.find(End)]
        total_data.pop()
        break
  return ''.join(total_data)

s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
s.connect((host, port))

s.send("some_request")
data = s.recv_end(1024)
print "<---- " + str(data)

s.close()

I'm new to python and wondering if there is a way for the client to know that the server closed the connection and terminate.

I understand that the client would disconnect if I use normal s.recv(1024). But in my case, I need to send large data to the client so I have used a different function I found from http://code.activestate.com/recipes/408859-socketrecv-three-ways-to-turn-it-into-recvall/.

Is it like the server sends a empty string reply during the close of a connection and in my case, it would send a empty string without the end limiter and hence the client is listening forever ?

Answer 1

When you have a loop with recv or anything that reads from a socket or a pipe, you should stop reading as soon as you get a buffer with len 0 :

while True:
    data=the_socket.recv(8192)
    if len(data) == 0: break
    ...