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Attempting secure socket communication between client and server and getting An operation was attempted on something that is not a socket error

I am attempting to piece together a secure socket client server communication solution. I do not have experience in doing so, so have cobbled together what I believe are relevant sections. The idea is that the Server waits for connections, the client creates a connection that is secure and then communication can take place.
The code also utilizes secure communication in authorization with client and server keys and certificates.
client code:
class Client:
def __init__(self):
try:
self.host, self.port = "127.0.0.1", 65416
self.client_cert = os.path.join(os.path.dirname(__file__), "client.crt")
self.client_key = os.path.join(os.path.dirname(__file__), "client.key")
self._context = ssl.SSLContext()
self._context.load_cert_chain(self.client_cert, self.client_key)
self._sock = None
self._ssock = None
except Exception as e:
print("Error in Initializing")
def checkvalidclient(self):
# ---- Client Communication Setup ----
HOST = self.host # The server's hostname or IP address
PORT = self.port # The port used by the server
try:
self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._ssock = self._context.wrap_socket(self._sock,)
self._ssock.connect((HOST, PORT))
print ("Socket successfully created")
except socket.error as err:
print ("socket creation failed with error %s" %(err))
print('Waiting for connection')
Response = self._ssock.recv(1024)
while True:
Input = input('Say Something: ')
# s.send(str.encode(Input))
send_msg(self._ssock, str.encode(Input))
# Response = s.recv(1024)
Response = recv_msg(self._ssock)
if Response is not None:
print(Response.decode('utf-8'))
def closesockconnection(self):
self._ssock.close()
# ---- To Avoid Message Boundary Problem on top of TCP protocol ----
def send_msg(sock: socket, msg): # ---- Use this to send
# Prefix each message with a 4-byte length (network byte order)
msg = struct.pack('>I', len(msg)) + msg
sock.sendall(msg)
def recv_msg(sock: socket): # ---- Use this to receive
# Read message length and unpack it into an integer
raw_msglen = recvall(sock, 4)
if not raw_msglen:
return None
msglen = struct.unpack('>I', raw_msglen)[0]
# Read the message data
return recvall(sock, msglen)
def recvall(sock: socket, n: int):
# Helper function to receive n bytes or return None if EOF is hit
data = bytearray()
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data.extend(packet)
return data
client = Client()
client.checkvalidclient()
Server code:
import socket
import os
import ssl
from os import path
from _thread import *
import struct # Here to convert Python data types into byte streams (in string) and back
# ---- To Avoid Message Boundary Problem on top of TCP protocol ----
def send_msg(sock: socket, msg): # ---- Use this to send
# Prefix each message with a 4-byte length (network byte order)
msg = struct.pack('>I', len(msg)) + msg
sock.sendall(msg)
def recv_msg(sock: socket): # ---- Use this to receive
# Read message length and unpack it into an integer
raw_msglen = recvall(sock, 4)
if not raw_msglen:
return None
msglen = struct.unpack('>I', raw_msglen)[0]
# Read the message data
return recvall(sock, msglen)
def recvall(sock: socket, n: int):
# Helper function to receive n bytes or return None if EOF is hit
try:
data = bytearray()
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data.extend(packet)
return data
except Exception as e:
print("Exception in recvall : " + str(e))
# ---- Server Communication Setup
class Server:
def __init__(self):
self.HOST = '127.0.0.1' # Standard loopback interface address (localhost)
self.PORT = 65416 # Port to listen on (non-privileged ports are > 1023)
self.ThreadCount = 0
self.server_cert = path.join(path.dirname(__file__), "server.crt")
self.server_key = path.join(path.dirname(__file__), "server.key")
self.client_cert = path.join(path.dirname(__file__), "client.crt")
self._context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
self._context.verify_mode = ssl.CERT_REQUIRED
self._context.load_cert_chain(self.server_cert, self.server_key)
self._context.load_verify_locations(self.client_cert)
self.sock = None
def connect(self):
try: # create socket
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
print ("Socket successfully created")
except socket.error as err:
print ("socket creation failed with error %s" %(err))
try: # bind socket to an address
self.sock.bind((self.HOST, self.PORT))
except socket.error as e:
print(str(e))
print('Waiting for a Connection..')
self.sock.listen(3)
def threaded_client(self, conn: socket):
conn.send(str.encode('Welcome to the Server'))
while True:
# data = conn.recv(2048) # receive message from client
data = recv_msg(conn)
print(data)
if data is not None:
reply = 'Server Says: ' + data.decode('utf-8')
if not data:
break
# conn.sendall(str.encode(reply))
send_msg(conn, str.encode(reply))
#conn.close()
def waitforconnection(self):
while True:
Client, addr = self.sock.accept()
self._context.wrap_socket(Client, server_side=True)
print('Connected to: ' + addr[0] + ':' + str(addr[1]))
start_new_thread(self.threaded_client, (Client, )) # Calling threaded_client() on a new thread
self.ThreadCount += 1
print('Thread Number: ' + str(self.ThreadCount))
#self.sock.close()
server = Server()
server.connect()
server.waitforconnection()
The lines:
def threaded_client(self, conn: socket):
conn.send(str.encode('Welcome to the Server'))
result in the error:
[WinError 10038] An operation was attempted on something that is not a socket
When I removed the certificate related lines in client:
self.client_cert = os.path.join(os.path.dirname(__file__), "client.crt")
self.client_key = os.path.join(os.path.dirname(__file__), "client.key")
self._context = ssl.SSLContext()
self._context.load_cert_chain(self.client_cert, self.client_key)
and the certificate related lines in the server:
self.server_cert = path.join(path.dirname(__file__), "server.crt")
self.server_key = path.join(path.dirname(__file__), "server.key")
self.client_cert = path.join(path.dirname(__file__), "client.crt")
self._context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
self._context.verify_mode = ssl.CERT_REQUIRED
self._context.load_cert_chain(self.server_cert, self.server_key)
self._context.load_verify_locations(self.client_cert)
self.sock = None
and a couple of small changes to remove the certificate related functionality, everything seemed to work, the client could send messages to the server and the server could respond (and the client displayed the response).
When however I added the context related certificates I start getting the error:
An operation was attempted on something that is not a socket
The server waits at:
Client, addr = self.sock.accept()
and continues to run once the client has called (in the client.py file):
self._ssock.connect((HOST, PORT))
The server then reaches the lines:
def threaded_client(self, conn: socket):
conn.send(str.encode('Welcome to the Server'))
where it fails on this error.
Printing the terminal, a traceback and exception error results in:
Socket successfully created
Waiting for a Connection..
Connected to: 127.0.0.1:57434
Thread Number: 1
Traceback (most recent call last):
File "c:\testcode\Server.py", line 71, in threaded_client
conn.send(str.encode('Welcome to the Server'))
OSError: [WinError 10038] An operation was attempted on something that is not a socket
My knowledge is limited and I cannot find more examples of secure multi threaded two way communication client to server socket code. The idea is to ensure the client is authorized to communicate with the server before transmission happens.
Any ideas on where I am failing?
Thanks

Ok, It seems like I was close, but had a couple of tweaks to do.
The solution of:
SSL/TLS client certificate verification with Python v3.4+ SSLContext
and the commenters here, helped me get over the finish line.
Server code:
import socket
import os
from socket import AF_INET, SOCK_STREAM, SO_REUSEADDR, SOL_SOCKET, SHUT_RDWR
import ssl
from os import path
from _thread import *
import struct # Here to convert Python data types into byte streams (in string) and back
import traceback
# ---- To Avoid Message Boundary Problem on top of TCP protocol ----
def send_msg(sock: socket, msg): # ---- Use this to send
# Prefix each message with a 4-byte length (network byte order)
msg = struct.pack('>I', len(msg)) + msg
sock.sendall(msg)
def recv_msg(sock: socket): # ---- Use this to receive
# Read message length and unpack it into an integer
raw_msglen = recvall(sock, 4)
if not raw_msglen:
return None
msglen = struct.unpack('>I', raw_msglen)[0]
# Read the message data
return recvall(sock, msglen)
def recvall(sock: socket, n: int):
# Helper function to receive n bytes or return None if EOF is hit
try:
data = bytearray()
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data.extend(packet)
return data
except Exception as e:
print("Exception in recvall : " + str(e))
# ---- Server Communication Setup
class Server:
def __init__(self):
self.HOST = '127.0.0.1' # Standard loopback interface address (localhost)
self.PORT = 65416 # Port to listen on (non-privileged ports are > 1023)
self.ThreadCount = 0
self.server_cert = path.join(path.dirname(__file__), "server.crt")
self.server_key = path.join(path.dirname(__file__), "server.key")
self.client_cert = path.join(path.dirname(__file__), "client.crt")
self._context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
self._context.verify_mode = ssl.CERT_REQUIRED
self._context.load_cert_chain(certfile=self.server_cert, keyfile=self.server_key)
self._context.load_verify_locations(cafile=self.client_cert)
self.sock = None
def connect(self):
try: # create socket
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) ###<-- socket.socket() ???
print ("Socket successfully created")
except socket.error as err:
print ("socket creation failed with error %s" %(err))
try: # bind socket to an address
self.sock.bind((self.HOST, self.PORT))
except socket.error as e:
print(str(e))
print('Waiting for a Connection..')
self.sock.listen(3)
def threaded_client(self, conn: socket):
try:
conn.send(str.encode('Welcome to the Server'))
while True:
data = recv_msg(conn)
print("data")
print(data)
if data is not None:
reply = 'Server Says: ' + data.decode('utf-8')
if not data:
break
send_msg(conn, str.encode(reply))
except Exception as e:
print(traceback.format_exc())
print(str(e))
finally:
print("Closing connection")
conn.shutdown(socket.SHUT_RDWR)
conn.close()
#conn.close()
def waitforconnection(self):
while True:
Client, addr = self.sock.accept()
conn = self._context.wrap_socket(Client, server_side=True)
print('Connected to: ' + addr[0] + ':' + str(addr[1]))
print("SSL established. Peer: {}".format(conn.getpeercert()))
start_new_thread(self.threaded_client, (conn, )) # Calling threaded_client() on a new thread
self.ThreadCount += 1
print('Thread Number: ' + str(self.ThreadCount))
#self.sock.close()
server = Server()
server.connect()
server.waitforconnection()
Client code:
import socket
import struct # Here to convert Python data types into byte streams (in string) and back
import sys
import ssl
import socket
import selectors
import types
import io
import os
import time
import requests
from pathlib import Path
import mysql.connector as mysql
from loguru import logger as log
from utils.misc import read_py_config
import json
import rsa
import base64
class Client:
def __init__(self):
self.host, self.port = "127.0.0.1", 65416
self.client_cert = os.path.join(os.path.dirname(__file__), "client.crt")
self.client_key = os.path.join(os.path.dirname(__file__), "client.key")
self.server_crt = os.path.join(os.path.dirname(__file__), "server.crt")
self.sni_hostname = "example.com"
self._context = ssl.create_default_context(ssl.Purpose.SERVER_AUTH, cafile=self.server_crt)
self._context.load_cert_chain(certfile=self.client_cert, keyfile=self.client_key)
self._sock = None
self._ssock = None
def checkvalidclient(self):
# ---- Client Communication Setup ----
HOST = self.host # The server's hostname or IP address
PORT = self.port # The port used by the server
try:
self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._ssock = self._context.wrap_socket(self._sock, server_side=False, server_hostname=self.sni_hostname)
self._ssock.connect((HOST, PORT))
print ("Socket successfully created")
except socket.error as err:
print ("socket creation failed with error %s" %(err))
print('Waiting for connection')
Response = self._ssock.recv(1024)
if Response is not None:
print(Response.decode('utf-8'))
while True:
Input = input('Say Something: ')
send_msg(self._ssock, str.encode(Input))
Response = recv_msg(self._ssock)
if Response is not None:
print(Response.decode('utf-8'))
def closesockconnection(self):
self._ssock.close()
# ---- To Avoid Message Boundary Problem on top of TCP protocol ----
def send_msg(sock: socket, msg): # ---- Use this to send
# Prefix each message with a 4-byte length (network byte order)
msg = struct.pack('>I', len(msg)) + msg
sock.sendall(msg)
def recv_msg(sock: socket): # ---- Use this to receive
# Read message length and unpack it into an integer
raw_msglen = recvall(sock, 4)
if not raw_msglen:
return None
msglen = struct.unpack('>I', raw_msglen)[0]
# Read the message data
return recvall(sock, msglen)
def recvall(sock: socket, n: int):
# Helper function to receive n bytes or return None if EOF is hit
data = bytearray()
while len(data) < n:
packet = sock.recv(n - len(data))
if not packet:
return None
data.extend(packet)
return data
Also ensure (as per the link) that the certificate creation is correct.
There is also another useful link at:
Exploring HTTPS With Python
Which covers HTTPS, specifically the Wireshark section allows you to monitor the traffic from client to server. After completing the above and deploying Wireshark I see that the data is encrypted. Any editing of the certificates (manually) causes the app to fail.
There still needs to be additions of try and except if the communication is halted midway etc. But hoping it will smooth the journey for others.
Thanks to the commenters, helped lead me on the way to solution.

Sending a message after file transfer completion

I'm new to socket programming. I'm trying to send 4 files from one host to another. Here is the code:
sender:
from __future__ import print_function
import socket
from struct import pack
HOST = '10.0.0.2'
PORT = 12345
BUFSIZE = 4096
def send(sock, data):
while data:
sent = sock.send(data)
data = data[sent:]
def send_file(fname):
with open(fname, 'rb') as f:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
sock.connect((HOST, PORT))
except socket.error as err:
print(err, HOST, PORT)
sock.close()
return
# Send the file name length & the filename itself in one packet
send(sock, pack('B', len(fname)) + fname.encode())
while True:
data = f.read(BUFSIZE)
if not data:
break
send(sock, data)
sock.close()
fnames = [
'1.jpg',
'2.jpg',
'3.jpg',
'4.jpg',
]
def main():
for fname in fnames:
send_file(fname)
if __name__ == '__main__':
main()
Receiver:
from __future__ import print_function
import socket
from struct import unpack
HOST = '10.0.0.2'
PORT = 12345
BUFSIZE = 4096
class Receiver:
''' Buffer binary data from socket conn '''
def __init__(self, conn):
self.conn = conn
self.buff = bytearray()
def get(self, size):
''' Get size bytes from the buffer, reading
from conn when necessary
'''
while len(self.buff) < size:
data = self.conn.recv(BUFSIZE)
if not data:
break
self.buff.extend(data)
# Extract the desired bytes
result = self.buff[:size]
# and remove them from the buffer
del self.buff[:size]
return bytes(result)
def save(self, fname):
''' Save the remaining bytes to file fname '''
with open(fname, 'wb') as f:
if self.buff:
f.write(bytes(self.buff))
while True:
data = self.conn.recv(BUFSIZE)
if not data:
break
f.write(data)
def main():
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
try:
sock.bind((HOST, PORT))
except socket.error as err:
print('Bind failed', err)
return
sock.listen(1)
print('Socket now listening at', HOST, PORT)
try:
while True:
conn, addr = sock.accept()
print('Connected with', *addr)
# Create a buffer for this connection
receiver = Receiver(conn)
# Get the length of the file name
name_size = unpack('B', receiver.get(1))[0]
# Get the file name itself
name = receiver.get(name_size).decode()
print('name', name)
# Save the file
receiver.save(name)
conn.close()
print('saved\n')
# Hit Break / Ctrl-C to exit
except KeyboardInterrupt:
print('\nClosing')
sock.close()
if __name__ == '__main__':
main()
File transfer is working fine and there is no problem with it. Now I want to send a simple string like "finish" after sending all files, so that receiver will understand that the transfer is completed and it will do some other tasks based on this finish message (however, it still can receive messages at the same time).
I tried to do this by adding another function called sendMessage() to the sender code and a function called recvMessage() to the receiver. Here are the changed codes:
Sender:
from __future__ import print_function
import socket
from struct import pack
HOST = '10.0.0.2'
PORT = 12345
BUFSIZE = 4096
BUFFER_SIZE = 1024
MESSAGE = "Finish!"
def send(sock, data):
while data:
sent = sock.send(data)
data = data[sent:]
#Updated part for sending message
def sendMessage(message):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((HOST, PORT))
sock.send(message)
data = sock.recv(BUFFER_SIZE)
sock.close()
print ("received data:", data)
def send_file(fname):
with open(fname, 'rb') as f:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
sock.connect((HOST, PORT))
except socket.error as err:
print(err, HOST, PORT)
sock.close()
return
# Send the file name length & the filename itself in one packet
send(sock, pack('B', len(fname)) + fname.encode())
while True:
data = f.read(BUFSIZE)
if not data:
break
send(sock, data)
sock.close()
fnames = [
'1.jpg',
'2.jpg',
'3.jpg',
'4.jpg',
]
def main():
for fname in fnames:
send_file(fname)
sendMessage(MESSAGE)
if __name__ == '__main__':
main()
receiver:
from __future__ import print_function
import socket
from struct import unpack
HOST = '10.0.0.2'
PORT = 12345
BUFSIZE = 4096
BUFFER_SIZE = 20
class Receiver:
''' Buffer binary data from socket conn '''
def __init__(self, conn):
self.conn = conn
self.buff = bytearray()
def get(self, size):
''' Get size bytes from the buffer, reading
from conn when necessary
'''
while len(self.buff) < size:
data = self.conn.recv(BUFSIZE)
if not data:
break
self.buff.extend(data)
# Extract the desired bytes
result = self.buff[:size]
# and remove them from the buffer
del self.buff[:size]
return bytes(result)
def save(self, fname):
''' Save the remaining bytes to file fname '''
with open(fname, 'wb') as f:
if self.buff:
f.write(bytes(self.buff))
while True:
data = self.conn.recv(BUFSIZE)
if not data:
break
f.write(data)
#Updated part for receiving message
def recvMessage(conn):
while 1:
data = conn.recv(BUFFER_SIZE)
if not data: break
print("received data:", data)
conn.send(data) # echo
def main():
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
try:
sock.bind((HOST, PORT))
except socket.error as err:
print('Bind failed', err)
return
sock.listen(1)
print('Socket now listening at', HOST, PORT)
try:
while True:
conn, addr = sock.accept()
print('Connected with', *addr)
# Create a buffer for this connection
receiver = Receiver(conn)
# Get the length of the file name
name_size = unpack('B', receiver.get(1))[0]
# Get the file name itself
name = receiver.get(name_size).decode()
print('name', name)
# Save the file
receiver.save(name)
conn.close()
print('saved\n')
recvMessage(conn)
# Hit Break / Ctrl-C to exit
except KeyboardInterrupt:
print('\nClosing')
sock.close()
if __name__ == '__main__':
main()
but after running these codes both sender and receiver freeze after the complete transfer of 4 files and nothing happens. What's wrong and how can I do this?

I suspect you're falling prey to buffering here:
def sendMessage(message):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((HOST, PORT))
sock.send(message)
data = sock.recv(BUFFER_SIZE)
sock.close()
print ("received data:", data)
You perform a send, then immediately try to recv. Except stream connections tend to buffer to avoid excessive packet overhead, so odds are, you don't actually send anything yet, the server doesn't see anything so it doesn't respond, and both sides are blocked waiting for data.
The simplest solution here is to shut down the send side port for writing once you've sent the message, which forces out the last data and lets the receiver know you're done:
def sendMessage(message):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((HOST, PORT))
sock.sendall(message) # sendall makes sure the *whole* message is sent
sock.shutdown(socket.SHUT_WR) # We're done writing
data = sock.recv(BUFFER_SIZE)
sock.close()
print("received data:", data)
On the receiver side you have a bigger problem: You close the connection before trying to receive at all:
while True:
conn, addr = sock.accept()
print('Connected with', *addr)
# Create a buffer for this connection
receiver = Receiver(conn)
# Get the length of the file name
name_size = unpack('B', receiver.get(1))[0]
# Get the file name itself
name = receiver.get(name_size).decode()
print('name', name)
# Save the file
receiver.save(name)
conn.close() # Closed here!!!
print('saved\n')
recvMessage(conn) # Used again here!!!
So move the close after the recvMessage call, and change recvMessage to use setsockopt to turn on TCP_NODELAY, so buffering isn't occurring (otherwise the echo back may end up buffering indefinitely, though shutting down the sender for write does mean you're likely to detect the sender is done and exit the loop then close the connection, so it may work fine without TCP_NODELAY, as long as the sender isn't expecting to receive data and respond further):
def recvMessage(conn):
# Disable Nagle algorithm so your echoes don't buffer
conn.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
while 1:
data = conn.recv(BUFFER_SIZE)
if not data: break
print("received data:", data)
conn.sendall(data) # echo using sendall, again, to ensure it's all really sent

Python Socket Program - NameError: name 'self' is not defined. I changed the localhost, ports etc but this error refuses to go away

import socket
MAX_BUFFER_SIZE = 4096
class ClientSocket:
def __init__(self):
print("Client socket started....")
self.soc = None
def send_to_Server(self, data):
print('Time to send data to Server..... %s', data)
self.soc.send(data.encode("utf8"))
def receive_from_Server(self):
print('Time to receive from Server.....')
result_bytes = self.soc.recv(MAX_BUFFER_SIZE)
result_string = result_bytes.decode("utf8")
print("Result from server is {}".format(result_string))
def start_client(self):
self.soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.soc.connect(("localhost", 8000))
print('Client connected....')
husainshoab#hs-Len:~$ python IOTDeviceSocket.py
Traceback (most recent call last):
File "IOTDeviceSocket.py", line 7, in
class ClientSocket:
File "IOTDeviceSocket.py", line 11, in ClientSocket
self.soc = None
NameError: name 'self' is not defined

There appears to be nothing wrong with your code. I just used it to create a simple test application
# ClientSocket.py
import socket
MAX_BUFFER_SIZE = 4096
class ClientSocket:
def __init__(self):
print("Client socket started....")
self.soc = None
def send_to_Server(self, data):
print('Time to send data to Server..... %s', data)
self.soc.send(data.encode("utf8"))
def receive_from_Server(self):
print('Time to receive from Server.....')
result_bytes = self.soc.recv(MAX_BUFFER_SIZE)
result_string = result_bytes.decode("utf8")
print("Result from server is {}".format(result_string))
def start_client(self):
self.soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.soc.connect(("localhost", 8000))
print('Client connected....')
cs = ClientSocket()
cs.start_client()
cs.send_to_Server('Hello')
cs.receive_from_Server()
here's a simple test server which just spits back some JSON data
# test_server.py
import socket
from datetime import datetime
import json
def logMessage(clientMessage):
logTime = datetime.today();
msg = "{} | {}\n".format(logTime, clientMessage)
print msg
TCP_PORT = 8000
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(('localhost', TCP_PORT))
# listen() puts the socket into server mode,
server.listen(1)
while True:
# wait for an incoming connection
connection, address = server.accept()
try:
# receive data in chunks of 64 bytes
while True:
data = connection.recv(64)
# how do we know if we received all the data?
if data:
# we received data from the client, log it to the file
logMessage(data)
response = {
'name' : 'Jonathan Swift',
'occupation' : 'author'
}
jsonResponse = json.dumps(response)
messageLength = len(jsonResponse)
bytesSent = 0
# send a response to the client after turning our dict into
# a JSON string
while(bytesSent < messageLength):
sent = connection.send(jsonResponse)
bytesSent += sent
else:
# no data, break out of receiving loop
break
except Exception as e:
raise
finally:
connection.close()

import socket
MAX_BUFFER_SIZE = 4096
class ClientSocket:
soc = None
def __init__(self):
print("Client socket started....")
self.soc = None
def send_to_Server(self, data):
print('Time to send data to Server..... %s', data)
self.soc.send(data.encode("utf8"))
def receive_from_Server(self):
print('Time to receive from Server.....')
result_bytes = self.soc.recv(MAX_BUFFER_SIZE)
result_string = result_bytes.decode("utf8")
print("Result from server is {}".format(result_string))
def start_client(self):
self.soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.soc.connect(("localhost", 8000))
print('Client connected....')
you should define the soc variable after class statement so that you can use it globally.

Socket programming client send and receive file at same time

I am trying this scenario:
Client sends file to server
Server updates on file and save it
Sends updated file back to client
Steps 1 and 2 are done correctly as I wanted but when client finishes sending the socket closes. I've tried this code but its not working. Any suggestions?
Client:
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
H = socket.gethostname()
P = 1111
s.connect((H,P))
with open('File.txt', 'rb') as fileName:
for data in fileName:
s.sendall(data)
with open('ReFile.txt', 'wb') as File:
while True:
data = s.recv(1024)
print data
if not data:
break
File.write(data)
File.close()
Server:
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
H= socket.gethostname()
P = 1111
s.bind((H, P))
s.listen(6)
c, address = s.accept()
print 'Connection with ' , address
with open('ReFile.txt', 'wb') as RecFile:
while True:
data = c.recv(1024)
print data
if not data:
break
RecFile.write(data)
RecFile.write("updated version")
RecFile.close()
with open('ReFile.txt', 'rb') as file:
for data in file:
s.sendall(data)
s.close()

Try this:
Server:
import socket
s = socket.socket()
H = socket.gethostname()
P = 1111
s.bind((H, P))
s.listen(6)
c, address = s.accept()
print 'Connection with ', address
lenF = int(c.recv(1024))
if lenF != 0:
c.sendall('Send data')
data = c.recv(lenF)
data += "\nUpdated Version"
RecFile = open('ReFile.txt','w')
RecFile.write(str(data))
RecFile.close()
fileN = open('ReFile.txt')
data = fileN.read(-1)
fileN.close()
lenF = len(data)
c.send(str(lenF))
if c.recv(5) == 'Ready':
c.send(data)
Here I am using lenF variable to get the size of file that I am getting from the client.
Client:
import socket
s = socket.socket()
H = socket.gethostname()
P = 1111
s.connect((H,P))
fileName = open('file.txt')
data = fileName.read(-1)
fileName.close()
dataL = int(len(data))
s.send(str(dataL))
validCheck = s.recv(9)
if validCheck == 'Send data':
print 'Sending file.......'
s.send(data)
dataL = int(s.recv(1024))
if dataL != 0:
s.send('Ready')
data = s.recv(dataL)
File = open('ReFile.txt','w')
File.write(data)
File.close()
Here I am using dataL variable to receive data length(file) and sending it.

UDP TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

I'm completely newbie to python and computer networking. While working on Uni project I have faced a problem. What am I doing wrong? Any help will me much appreciated.
Here is server side:
import socket
def Main():
host = "127.0.0.1"
port = 5000
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind((host, port))
print ("Server Started.")
while True:
data, addr = s.recvfrom(1024)
print ("message from: ") + str(addr)
print ("from connected user: ") + str(data.decode('utf-8'))
data = str(data).upper()
print ("sending: ") + str(data)
s.sendto(data, addr)
s.close()
if __name__ == '__main__':
Main()
Here is my client side:
import socket
def Main():
host = "127.0.0.1"
port = 5000
server = ('127.0.0.1', 5000)
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind((host, port))
message = input('->')
while message != 'q':
s.sendto(message.encode('utf-8'), server)
data, addr = s.recvfrom(1024)
print ('Received from server: ') + str(data)
message = input('->')
s.close()
if __name__ == '__main__' :
Main()

There were a couple of issues; mostly with the printing.
You had a few instances of print('some text') + str(data); this won't work, because while print() outputs to the screen (STDOUT) it returns None, so what you were actually doing was trying to concatenate None + str(data)
What you need is print('some text' + str(data)).
Additionally, there was as issue on the server-side where you echo the data received from the client back to the client- it needed to be re-encoded as a bytearray (it comes in as a bytearray, gets converted to a utf-8 string for display, it needs to go back to bytearray before replying).
In summary, server:
import socket
def Main():
host = "127.0.0.1"
port = 5000
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind((host, port))
print("Server Started.")
while True:
try:
data, addr = s.recvfrom(1024)
print("message from: " + str(addr)) # moved string concatenation inside print method
print("from connected user: " + str(data.decode('utf-8'))) # moved string concatenation inside print method
data = str(data).upper()
print("sending: " + str(data)) # moved string concatenation inside print method
s.sendto(data.encode('utf-8'), addr) # needed to re-encode data into bytearray before sending
except KeyboardInterrupt: # added for clean CTRL + C exiting
print('Quitting')
break
s.close()
if __name__ == '__main__':
Main()
And the client:
import socket
def Main():
host = "127.0.0.1"
port = 5001
server = ('127.0.0.1', 5000)
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind((host, port))
message = input('->')
while message != 'q':
try:
s.sendto(message.encode('utf-8'), server)
data, addr = s.recvfrom(1024)
print('Received from server: ' + str(data)) # moved string concatenation inside print method
message = input('->')
except KeyboardInterrupt: # added for clean CTRL + C exiting
print('Quitting')
break
s.close()
if __name__ == '__main__':
Main()