I am trying to write a program for file transfer using sockets. The server end of the code is running fine. However, in the client side I get the following error
Traceback (most recent call last):
File "client.py", line 54, in <module>
uploadFiles(directory)
File "client.py", line 36, in uploadFiles
transferFile(fname)
File "client.py", line 13, in transferFile
cs.connect((HOST, 36258))
File "/usr/lib/python2.7/socket.py", line 224, in meth
return getattr(self._sock,name)(*args)
socket.error: [Errno 111] Connection refused
My code is as follows
import os
import socket
def transferFile(fname):
HOST = '127.0.0.1'
CPORT = 36258
MPORT = 36250
FILE = fname
cs = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
cs.connect((HOST, 36258))
cs.send("SEND " + FILE)
cs.close()
ms = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
ms.connect((HOST, MPORT))
f = open(FILE, "rb")
data = f.read()
f.close()
ms.send(data)
ms.close()
def uploadFiles(directory):
home = os.getenv("HOME")
folder = str(home + "/" + directory)
os.chdir(folder)
dirList = os.listdir(folder)
print dirList
for fname in dirList:
if fname.endswith('.bin'):
transferFile(fname)
os.chdir(os.getenv("HOME"))
directory = "testdownload"
if not os.path.exists(directory):
os.makedirs(directory)
os.chdir(directory)
uploadFiles(directory)
I tried looking for help on Google and other posts on Stack Overflow, none of them helped. Can someone please help me? The line numbers may be different since I pasted only some part of the code
The problem obviously was (as you figured it out) that port 36250 wasn't open on the server side at the time you tried to connect (hence connection refused). I can see the server was supposed to open this socket after receiving SEND
command on another connection, but it apparently was "not opening [it] up in sync with the client side".
Well, the main reason would be there was no synchronisation whatsoever. Calling:
cs.send("SEND " + FILE)
cs.close()
would just place the data into a OS buffer; close
would probably flush the data and push into the network, but it would almost certainly return before the data would reach the server. Adding sleep
after close
might mitigate the problem, but this is not synchronisation.
The correct solution would be to make sure the server has opened the connection. This would require server sending you some message back (for example OK
, or better PORT 36250
to indicate where to connect). This would make sure the server is already listening.
The other thing is you must check the return values of send
to make sure how many bytes was taken from your buffer. Or use sendall
.
(Sorry for disturbing with this late answer, but I found this to be a high traffic question and I really didn't like the sleep idea in the comments section.)