Working with OOB messages

README.md

to generate test file head -c 100000 /dev/urandom > t.txt was used

client.py

import socket
import sys


def write_progress(transmitter):
    sys.stdout.write('\rTransmitted %d bytes' % transmitter)
    sys.stdout.flush()


HOST = 'localhost'    # The remote host
PORT = 8086              # The same port as used by the server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
received = 0
while True:
    try:
        flag = s.recv(1, socket.MSG_OOB)
    except socket.error, value: #(value,message):
        flag = None
    if flag:
        write_progress(received)
    else:
        #recv usual data
        data = s.recv(64)
        if not data:
            break
        received += len(data)

write_progress(received)
print '\n'
s.close()

server.py

import socket
import time

port = 8086
host = 'localhost'
file_obj = file('t.txt')


def read_file_by_chunks(file_obj, chunk_size):
    """ Reads file by fixed-length chunks
    :type file_obj: file
    """
    file_obj.seek(0)
    while True:
        chunk = file_obj.read(chunk_size)
        if not chunk:
            break
        yield chunk

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))

s.listen(1)
conn, addr = s.accept()
received = 0
i = 0
for chunk in read_file_by_chunks(file_obj, 64):
    i += 1
    received += len(chunk)
    conn.send(chunk)
    # each 2 iteration force client to show progress
    if i % 2 == 0:
        conn.send('!', socket.MSG_OOB)
    time.sleep(1) # 1 seconds delay
conn.close()
s.close()