Things to consider while failproofing socket communciation - python

I have a simple client/server socket program written in python. So far I think I have managed to deal with two types of certain socket errors.
server is not alive when the client is open (Connectionrejected)
server shuts down while the client is open (Connectionreset)
I am wondering what other errors I should be accounting for. When the client sends a message and the server is closed before the send happens, the client waits until it can reconnect and sends the message however I am not sure if that covers all the cases where the message can be lost or not transmitted completely.
server.py
import socket
import threading
HEADER = 8
PORT = 5050
SERVER = "127.0.0.1" #socket.gethostbyname(socket.gethostname())
ADDR = (SERVER, PORT)
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "exit"
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server.bind(ADDR)
def close():
server.shutdown(socket.SHUT_RDWR)
server.close()
print ("closed")
def handle_client(conn, addr):
print(f"[NEW CONNECTION] {addr} connected.")
connected = True
while connected:
msg_length = conn.recv(HEADER).decode(FORMAT)
if msg_length:
msg_length = int(msg_length)
msg = conn.recv(msg_length).decode(FORMAT)
if msg == DISCONNECT_MESSAGE:
connected = False
print(f"[{addr}] {msg}")
conn.send("Barcode received".encode(FORMAT))
conn.shutdown(socket.SHUT_RDWR)
conn.close()
def start():
server.listen()
print(f"[LISTENING] Server is listening on {SERVER}")
while True:
conn, addr = server.accept()
thread = threading.Thread(target=handle_client, args=(conn, addr))
thread.start()
print(f"[ACTIVE CONNECTIONS] {threading.active_count() - 1}")
print("[STARTING] server is starting...")
start()
client.py
import socket
import datetime
import time
HEADER = 8
PORT = 5050
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "exit"
SERVER = "127.0.0.1"
ADDR = (SERVER, PORT)
def check_connection(ADDR):
print("Trying to connect to the server...")
connected = False
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while not connected:
try:
client.connect(ADDR)
except socket.error as error:
connected = False
time.sleep(0.01)
print("Can't connect.Retrying...")
#print(connected)
else:
connected = True
print("Connected to the server")
return client
def send(msg,client,ADDR):
message = msg.encode(FORMAT)
msg_length = len(message)
send_length = str(msg_length).encode(FORMAT)
send_length += b' ' * (HEADER - len(send_length))
sending = True
while sending :
try:
cl_ls[0].send(send_length)
cl_ls[0].send(message)
print(cl_ls[0].recv(2048).decode(FORMAT))
sending = False
except socket.error as error:
cl_ls[0] = check_connection(ADDR)
cl_ls[0].send(send_length)
cl_ls[0].send(message)
sending = False
print(cl_ls[0].recv(2048).decode(FORMAT))
cl_ls = ["client"]
client = check_connection(ADDR)
cl_ls[0] = client
accept_more_barcodes = True
while accept_more_barcodes:
input_value = input("Type 'exit' to close input box ")
today = datetime.datetime.now()
date_time = today.strftime("%m/%d/%Y, %H:%M:%S")
input_value += ' *** ' + date_time
if (input_value).startswith("exit"):
accept_more_barcodes = False
else:
with open("barcodes.txt", "a") as f:
f.write(input_value + "\n")
send(input_value,cl_ls[0],ADDR)

Related

Sockets Python | chatting server multiple clients

i am trying to implement a TLS secured socket server in python, and i want multiple clients to connect to the server and talk to each other,
what i would like to do is that each client connecting can receive messages sent by other clients also,
Server code:
import socket
import threading
HEADER = 64
PORT = 5050
SERVER = socket.gethostbyname(socket.gethostname())
ADDR = (SERVER, PORT)
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "!DISCONNECT"
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(ADDR)
def handle_client(conn, addr):
print(f"[NEW CONNECTION] {addr} connected.")
connected = True
while connected:
msg_length = conn.recv(HEADER).decode(FORMAT)
if msg_length:
msg_length = int(msg_length)
msg = conn.recv(msg_length).decode(FORMAT)
if msg == DISCONNECT_MESSAGE:
connected = False
print(f"[{addr}] {msg}")
conn.send("Msg received".encode(FORMAT))
conn.close()
def start():
server.listen()
print(f"[LISTENING] Server is listening on {SERVER}")
while True:
conn, addr = server.accept()
thread = threading.Thread(target=handle_client, args=(conn, addr))
thread.start()
print(f"[ACTIVE CONNECTIONS] {threading.activeCount() - 1}")
print("[STARTING] server is starting ...")
start()
Client Code:
import socket
HEADER = 64
PORT = 5050
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "!DISCONNECT"
SERVER = "192.168.1.141"
ADDR = (SERVER, PORT)
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.connect(ADDR)
def send(msg):
message = msg.encode(FORMAT)
msg_length = len(message)
send_length = str(msg_length).encode(FORMAT)
send_length += b' ' * (HEADER - len(send_length))
client.send(send_length)
client.send(message)
print(client.recv(2048).decode(FORMAT))
send(input('[Send a Message]: '))
send(DISCONNECT_MESSAGE)
where can i add the TLS in this?:/
if something isn't right please inform me :)
---------------------EDIT------------------------------
SERVER:
import socket
import select
HEADER_LENGTH = 10
IP = "127.0.0.1"
PORT = 1234
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind((IP, PORT))
server_socket.listen(5)
sockets_list = [server_socket]
clients = {}
def receive_message(client_socket):
try:
message_header = client_socket.recv(HEADER_LENGTH)
if not len(message_header):
return False
message_length = int(message_header.decode('utf-8').strip())
return {"header": message_header, "data": client_socket.recv(message_length)}
except:
return False
while True:
read_sockets, _, exception_sockets = select.select(
sockets_list, [], sockets_list)
for notified_socket in read_sockets:
if notified_socket == server_socket:
client_socket, client_address = server_socket.accept()
user = receive_message(client_socket)
if user is False:
continue
sockets_list.append(client_socket)
clients[client_socket] = user
print(
f"Accepted new connection from {client_address[0]}:{client_address[1]} username: {user['data'].decode('utf-8')}")
else:
message = receive_message(notified_socket)
if message is False:
print(
f"closed connection from {clients[notified_socket]['data'].decode('utf-8')}")
sockets_list.remove(notified_socket)
del clients[notified_socket]
continue
user = clients[notified_socket]
print(
f"Received message from {user['data'].decode('utf-8')}: {message['data'].decode('utf-8')}")
for client_socket in clients:
if client_socket != notified_socket:
client_socket.send(
user['header'] + user['data'] + message['header'] + message['data'])
for notified_socket in exception_sockets:
sockets_list.remove(notified_socket)
del clients[notified_socket]
CLIENT:
from http import client
import socket
import select
import errno
import sys
import threading
HEADER_LENGTH = 10
IP = '127.0.0.1'
PORT = 1234
my_username = input("Username: ")
client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect((IP, PORT))
client_socket.setblocking(False)
username = my_username.encode('utf-8')
username_header = f"{len(username):<{HEADER_LENGTH}}".encode('utf-8')
client_socket.send(username_header + username)
def send_message():
message = input(f"{my_username} > ")
if message:
message = message.encode('utf-8')
message_header = f"{len(message):<{HEADER_LENGTH}}".encode('utf-8')
client_socket.send(message_header + message)
while True:
thread = threading.Thread(target=send_message)
thread.start()
try:
while True:
# receive things
username_header = client_socket.recv(HEADER_LENGTH)
if not len(username_header):
print("connection closed by the server")
sys.exit()
username_length = int(username_header.decode('utf-8').strip())
username = client_socket.recv(username_length).decode('utf-8')
message_header = client_socket.recv(HEADER_LENGTH)
message_length = int(message_header.decode('utf-8').strip())
message = client_socket.recv(message_length).decode('utf-8')
print(f"{username} > {message}")
except IOError as e:
if e.errno != errno.EAGAIN and e.errno != errno.EWOULDBLOCK:
print('Reading error', str(e))
sys.exit()
continue
except Exception as e:
print('General error', str(e))
sys.exit()
unfortunately, i cant seem to get the buffer to work right , other clients only receive other clients input when they send messages, so the output is always unordered correctly.

How to connect to Python socket server from another network

I'm new to socket programming and I'm trying to make a server with socket module. When working on a local network it works perfectly fine, but the problem comes when I'm trying to run it and connect from two different networks. I've tried many things that I saw on SO and the internet in general.
Server code:
import socket
import threading
SERVER = socket.gethostbyname('')
PORT = 12345
ADDR = (SERVER, PORT)
HEADER = 64
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = '!DISCONNECT'
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(ADDR)
def handle_client(conn, addr):
print(f'[NEW CONNECTION] {addr} connected.')
print(f'[ACTIVE CONNECTIONS] {threading.active_count() - 1}')
connected = True
while connected:
msg_lenght = conn.recv(HEADER).decode(FORMAT)
if msg_lenght:
msg_lenght = int(msg_lenght)
msg = conn.recv(msg_lenght).decode(FORMAT)
if msg == DISCONNECT_MESSAGE:
connected = False
print(f'[MESSAGE RECIEVED] FROM: {addr}; Message: {msg}')
conn.send('Message received!'.encode(FORMAT))
conn.close()
def start():
server.listen()
print(f'[LISTENING] Server is listening on {SERVER}')
while True:
conn, addr = server.accept()
thread = threading.Thread(target=handle_client, args=(conn, addr))
thread.start()
print(f'IP Address: {SERVER}')
print('[STARTING] Server is starting...')
start()
Client code:
import socket
SERVER = input('IP Address: ')
PORT = 5050
ADDR = (SERVER, PORT)
HEADER = 64
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = '!DISCONNECT'
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.connect(ADDR)
def send(msg):
message = msg.encode(FORMAT)
msg_lenght = len(message)
send_lenght = str(msg_lenght).encode(FORMAT)
send_lenght += b' ' * (HEADER - len(send_lenght))
client.send(send_lenght)
client.send(message)
while True:
user_Input = input('Message: ')
send(user_Input)
if user_Input == DISCONNECT_MESSAGE:
break
I tried making "rules" on the firewall that should make my port public or something. I have also tried different addresses because I was not sure which one to use.
Thanks in advance!

how can I send a message to all of my clients connect to my server (socket)

My code is below and I just can't seem to figure out how to send messages to my clients at once
Even when I try asking for help or anything like that they say Store each client and idk how to do that. also I did try it and look it up I did it but I want it to update instantly like discord
import socket
import threading
HEADER = 64
PORT = 5050
SERVER = socket.gethostbyname(socket.gethostname())
ADDR = (SERVER, PORT)
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "!stop"
NAME_MESSAGE = "!name"
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(ADDR)
def handle_client(client, addr):
print(f'[INFO] {addr} connected.')
while True:
msg_length = client.recv(HEADER).decode(FORMAT)
if not msg_length:
msg_length = int(msg_length)
msg = client.recv(msg_length).decode(FORMAT)
if msg == DISCONNECT_MESSAGE:
print(f'[DISCONNECT] {addr} Disconnected')
break
elif msg == NAME_MESSAGE:
name_length = client.recv(HEADER).decode(FORMAT)
if name_length:
name_length = int(name_length)
name = client.recv(name_length).decode(FORMAT)
addr = name
else:
<Idk what to put here>
else:
break
def start():
server.listen()
print(f'[INFO] Server is listening on {SERVER}')
while True:
conn, addr = server.accept()
thread = threading.Thread(target=handle_client, args=(conn, addr))
thread.start()
print(f'\n[INFO] Active connections: {threading.activeCount() - 1}')
print('[INFO] Server is starting...')
start()

Python socket client doesnt receive anything, hangs by recv.from(datasize)

I have to make a simple udp echo client and server, currently my problem is that the client hangs itself up at the code "data, address = sock.recvfrom(dataSize)". Here is my client and server code (I removed some api functions, so it aint long). I tried same ports and different ports and the same goes with the ip's but i dont get any message back. I tried the original file from a friend and his version works, I have the same port and ip and the same methods on both files, but it still keeps hanging at the echoClient method receiveMSG at the first line.
echoServerUDP.py
0<0# : ^
'''
#echo off
python "%~f0" %*
pause
exit /b 0
'''
#!/usr/bin/env python
import socket
import json
host = '0.0.0.0'
sport = 11111 # own port
dataSize = 1024
ip_adresses = {}
def echo_server():
receiveSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
receiveSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
receiveSock.bind((host,sport))
print("Starting up echo server on %s port %s" % (host, sport))
while True:
print("Waiting to receive message")
print("Generate a Session ...")
data, address = receiveSock.recvfrom(dataSize)
data = data.decode("utf-8")
if data:
print("receive data: %s from %s" % (data,address))
json_object = json.loads(data)
operation=json_object["operation"]
if operation == "register":
register(json_object["name"],json_object["value"],json_object["sid"])
json_message={"ergebnis":"ok"}
dump = json.dumps(json_message)
sendMSG(bytes(dump,encoding="utf-8"),address)
print("er")
if operation == "unregister":
unregister(json_object["name"],json_object["sid"])
if operation == "query":
query(json_object["sid"])
if operation == "reset":
reset(json_object["sid"])
print("sent %s bytes back to %s" % (data,address))
def sendMSG(data,address):
sendSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sendSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sendSock.sendto(data,address)
sendSock.close()
if __name__ == '__main__':
echo_server()
and here the echoClientUDP.py
0<0# : ^
'''
#echo off
python "%~f0" %*
pause
exit /b 0
'''
#!/usr/bin/env python
import socket
import time
import json
from random import randint
host = '127.0.0.1'
sport = 11111
dataSize = 1024
sid= randint(1,10000)
name=socket.gethostname()
own_ip = socket.gethostbyname(name)
def echo_client():
sendSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
json_message = {"operation":"register","name":name,"value":own_ip,"sid":sid}
dump = json.dumps(json_message)
print("Sending %s to %s:%s" % (dump,host,sport))
sendMSG(sendSock, dump)
data = receiveMSG(sendSock)
if data:
print("Received: %s" % data)
except Exception as err:
print("Socket error: %s" %str(err))
finally:
print("Closing connection to the server")
sendSock.close()
def sendMSG(sendSock, data):
sendSock.connect((host, sport))
sendSock.sendall(bytes(data,encoding="utf-8"))
def receiveMSG(sock):
data, address = sock.recvfrom(dataSize)
print(data)
return data
if __name__ == '__main__':
echo_client()
Please put more effort in some areas like you have not added any headers and you have gone more complicated i have also created a similar working script see and observe that script and make changes to your script
client.py :-
import socket
import sys
HEADER = 64
PORT = 65432
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "!DISCONNECT"
SERVER = socket.gethostbyname(socket.gethostname())
ADDR = (SERVER, PORT)
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.connect(ADDR)
def send(msg):
message = msg.encode(FORMAT)
msg_length = len(message)
send_length = str(msg_length).encode(FORMAT)
send_length += b' ' * (HEADER - len(send_length))
client.send(send_length)
client.send(message)
print(client.recv(2048).decode(FORMAT))
def chat():
while True:
try:
a = input()
if 'quit' in a:
sys.exit()
else:
send(a)
except Exception as e:
print(e)
sys.exit()
chat()
server.py :-
import socket
import threading
HEADER = 64
PORT = 65432
SERVER = socket.gethostbyname(socket.gethostname())
ADDR = (SERVER, PORT)
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "Bye"
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(ADDR)
def handle_client(conn, addr):
print(f"[NEW CONNECTION] {addr} connected.")
connected = True
while connected:
msg_length = conn.recv(HEADER).decode(FORMAT)
if msg_length:
msg_length = int(msg_length)
msg = conn.recv(msg_length).decode(FORMAT)
if msg == DISCONNECT_MESSAGE:
connected = False
print(f"[{addr}] left")
print(f"[{addr}] {msg}")
conn.send("Msg received".encode(FORMAT))
conn.close()
def start():
server.listen()
print(f"[LISTENING] Server is listening on {SERVER}")
while True:
conn, addr = server.accept()
thread = threading.Thread(target=handle_client, args=(conn, addr))
thread.start()
print(f"[ACTIVE CONNECTIONS] {threading.activeCount() - 1}")
print("[STARTING] server is starting...")
start()
and i have used threading here to make the process more fast.
First run the server.py in background and then run client.py to connect to the server.

How Client send Messages to Each Other

Using Sockets in python i have made a Server-client socket server which just send messages from the clients to the server and I want send messages between clients .
My Code Looks Like this....
Server.py
import socket
import threading
import pyaudio
PORT = 5070
HEADER = 64
FORMAT= "utf-8 "
DISCONNECT_MSG="!DISCONNECTED"
SERVER=socket.gethostbyname(socket.gethostname())
ADDR = (SERVER,PORT)
server = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
server.bind(ADDR)
connection_list = []
def handle_clinet(conn,addr):
print(f"[NEW CONNECTION]{addr} Connected")
CONNECTED = True
while CONNECTED:
msg_length = conn.recv(HEADER).decode(FORMAT)
if msg_length:
msg_length=int(msg_length)
msg = conn.recv(msg_length).decode(FORMAT)
if msg == DISCONNECT_MSG:
CONNECTED = False
if msg == "Disconnect":
conn.close()
CONNECTED = False
print("Dissconnected From the User...")
else:
print(msg)
def start():
server.listen()
while True:
conn,addr = server.accept()
thread = threading.Thread(target=handle_clinet,args=(conn,addr))
thread.start()
print(f"[ACTIVE CONNECTIONS] {threading.active_count() -1}")
connection_list.append(addr)
print(connection_list)
print("[Starting] the server...")
start()
Client.py
import socket
import threading
import pyaudio
PORT = 5070
HEADER = 64
FORMAT= "utf-8 "
DISCONNECT_MSG="!DISCONNECTED"
SERVER=socket.gethostbyname(socket.gethostname())
ADDR = (SERVER,PORT)
client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
client.connect(ADDR)
def send(msg):
message = msg.encode(FORMAT)
msg_length = len(message)
send_length = str(msg_length).encode(FORMAT)
send_length += b" " *(HEADER - len(send_length))
client.send(send_length)
client.send(message)
send("Hello World")
send_more =True
while send_more:
a = input()
send(a)
if a =="Disconnect":
print("!Disconnected From the Server.")
As seen from the above please suggest some Method to send messages between Clients.what changes i have to made in following code

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