Sending a file over TCP connection

Question

I want to send i file over TCP but when i try to run this the connection fails, the server receives the file but it gives this error: ERROR: Client timed out before sending a file

import selectors
import sys
from socket import *
import sock

sel1 = selectors.DefaultSelector()
print(len(sys.argv), sys.argv[1], sys.argv[2], sys.argv[3])

host = sys.argv[1]
port = int(sys.argv[2])
file = sys.argv[3]


try:
    # Instaniating socket object
    s = socket(AF_INET, SOCK_STREAM)
    # Getting ip_address through host name
    host_address = gethostbyname(host)
    # Connecting through host's ip address and port number using socket object
    s.connect((host_address, port))

    sel1.register(
        sock,
        selectors.EVENT_READ, data = None)
    fileToSend = open("file.txt", "rb")
    data = fileToSend.read(1024)
    while data:
        print("Sending...")
        fileToSend.close()
        s.send(b"Done")
        print("Done Sending")
        print(s.recv(1024))
        s.shutdown(2)
        s.close()



except:
# Returning False in case of an exception
 sys.stderr.write("Connection Failed")

Why are you closing the file and socket in the loop? You shouldn't close the socket until you've finished the loop and sent the whole file. — Barmar
– Barmar, Commented Jan 31, 2022 at 23:27
My advice is to skip the try/except until you get things working. Until that point, you WANT to see the actual exceptions, not your watered down message. — Tim Roberts
– Tim Roberts, Commented Jan 31, 2022 at 23:28
Thank You! now im undertsanding better the problem is that now it says that done is an unexpected keyword argument — Michael Garrido
– Michael Garrido, Commented Jan 31, 2022 at 23:37

Tim Roberts · Accepted Answer · 2022-01-31 23:33:55Z

1

Do the writing in a loop. There's no particular reason to chop it into 1024-byte pieces; the network stack will handle that for you.

By the way, your "Done" signal is not a good idea, especially since you're writing a binary file that might very well contain the word "Done". Remember that TCP is a streaming protocol. The other end does not see the exact packets you're sending. That is, just because you send 1024 bytes and 4 bytes, the other end might see it as reads of 256 and 772 bytes.

# Instaniating socket object
s = socket(AF_INET, SOCK_STREAM)
# Getting ip_address through host name
host_address = gethostbyname(host)
# Connecting through host's ip address and port number using socket object
s.connect((host_address, port))

fileToSend = open("file.txt", "rb")
print("Sending...")
while True:
    data = fileToSend.read(1024)
    if not data:
        break
    s.send( data )

fileToSend.close()
s.send(b"Done")
print("Done Sending")
print(s.recv(1024))
s.close()

answered Jan 31, 2022 at 23:33

Tim Roberts

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1 Comment

Michael Garrido Over a year ago

Thanks for you explanation, now the issue is that it says "No data expected until the accio command is issued!",

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