Send a file through sockets in Python

Question

I'm trying to make a program in python that implements sockets. Each client sends a PDF file and the server receives it and the title is changed to "file_(number).pdf" (e.g.: file_1.pdf). The problem presented is that only a client can send a file successfully. When a second client tries to send the file, the program crashes. What am I doing wrong and how can I solve my code to allow N clients (with N < 20) to connect to the server and transfer files?

Here's the server code:

import socket import sys s = socket.socket() s.bind(("localhost",9999)) s.listen(10) # Accepts up to 10 incoming connections.. sc, address = s.accept()  print address i=1 f = open('file_'+ str(i)+".pdf",'wb') # Open in binary i=i+1 while (True):      # We receive and write to the file.     l = sc.recv(1024)     while (l):         f.write(l)         l = sc.recv(1024) f.close()  sc.close() s.close() 

Here's the client code:

import socket import sys  s = socket.socket() s.connect(("localhost",9999)) f = open ("libroR.pdf", "rb") l = f.read(1024) while (l):     s.send(l)     l = f.read(1024) s.close() 

To simplify my code, I always use a book with file name "libroR.pdf", but in the full code it is chosen by a GUI.

Answer 1

You must put all the code from sc, address = s.accept() upto sc.close() into another loop or the server simply terminates after receiving the first file. It doesn't crash, the script is just finished.

[EDIT] Here is the revised code:

import socket import sys s = socket.socket() s.bind(("localhost",9999)) s.listen(10) # Accepts up to 10 connections.  while True:     sc, address = s.accept()      print address     i=1     f = open('file_'+ str(i)+".pdf",'wb') #open in binary     i=i+1     while (True):            # receive data and write it to file         l = sc.recv(1024)         while (l):                 f.write(l)                 l = sc.recv(1024)     f.close()       sc.close()  s.close() 

Note that s.listen(10) means "set maximum accept rate to 10 connections", not "stop after 10 connections".