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(Python) Socket Chat returning usernames as IP and Port

I'm working on a TCP socket chat assignment for school. I'm having trouble getting the last part done, which is returning all usernames to the client when it asks for it. The client can write /users to get all connected users usernames, but instead gets the IP and PORT they are connected to, output example:
('127.0.0.1', 54612)
Server Code:
import socket, threading
clients = []
nicknames = []
BYTES = 1024
FORMAT = "utf-8"
def server():
IP = "127.0.0.1"
PORT = 9090
BIND = (IP, PORT)
try:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.bind(BIND)
sock.listen()
print("Welcome to Budget-Discord!")
while True:
client, addr = sock.accept()
print("Connected with {}".format(str(addr)))
client.send('NICKNAME'.encode(FORMAT))
nickname = client.recv(BYTES).decode()
nicknames.append(nickname)
clients.append(client)
print("Nickname is {}".format(nickname))
print(nicknames)
#broadcast("{} joined!".format(nickname).encode(FORMAT))
client.send("\t >>> Connected to server!".encode(FORMAT))
threading.Thread(target=user_conn, args=[client, addr]).start()
except Exception as e:
print(f"Error, socket: {e}")
def sendall(msg: str, conn: socket.socket): # Broadcast
for client_conn in clients:
if client_conn != conn:
try:
client_conn.send(msg.encode())
except Exception as e:
print(f"Error, sendall: {e}")
byeee(client_conn)
def user_conn(conn: socket.socket, nicknames):
while True:
try:
msg = conn.recv(BYTES).decode()
if "/users" in msg:
conn.sendall(bytearray(str(nicknames).encode()))
if msg:
print(msg)
allchat = f"{msg}"
sendall(allchat, conn)
# else:
# pass
except Exception as e:
print(f"Error, user connection: {e}")
byeee(conn)
break
def byeee(conn: socket.socket):
if conn in clients:
conn.close()
clients.remove(conn)
if __name__ == "__main__":
server()
Client Code:
import socket, threading
IP = "127.0.0.1"
PORT = 9090
BIND = (IP, PORT)
BYTES = 1024
FORMAT = "utf-8"
nickname = input("Choose your nickname: ")
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.connect(BIND)
def receive():
while True:
try:
msg = client.recv(BYTES).decode()
if msg == 'NICKNAME':
client.send(nickname.encode())
# elif message == "/users"
else:
print(msg)
except Exception as e:
print(f"Error, client receive: {e}")
client.close()
break
def write():
while True:
msg = f"{nickname}: {input('')}"
client.send(msg.encode())
receive_t = threading.Thread(target=receive).start()
write_t = threading.Thread(target=write).start()
I have tried different things, got tuple errors for the most part so I converted the /users in the server module to bytearray...

In the function server, this line is sending addr as the second argument:
threading.Thread(target=user_conn, args=[client, addr]).start()
but the function user_conn has a second argument of nicknames:
def user_conn(conn: socket.socket, nicknames):
so send nicknames instead in server:
threading.Thread(target=user_conn, args=[client, nicknames]).start()

Receiving sockets blocking async?

The following code prints 1 every second and also tries to recieve udp packets from 244.0.2.60:4445
import socket
import struct
import asyncio
multicast_group = '224.0.2.60'
server_address = ('', 4445)
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(server_address)
group = socket.inet_aton(multicast_group)
mreq = struct.pack('4sL', group, socket.INADDR_ANY)
sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
async def check_server():
while True:
print(1)
await asyncio.sleep(1)
async def tag_server():
while True:
data, address = sock.recvfrom(1024)
data = data.decode("utf-8")
print(data, address)
# Create tasks
async def main():
await asyncio.gather(check_server(),tag_server())
# Run
asyncio.run(main())
I expect it to return the following way
1
1 # print 1 every second
1
1
b'packet' # receives packet
1
1
1
b'packet'
1
1
What I get is this :
1
Why does receiving packets block my program? What can I do to fix this?

How to receive all data after TCP connection has been closed by the peer?

Running some production code I faced the following problem:
When sending HTTP requests to some server, server immediately closes the connection after sending response, which, for some reason, results in data loss.
Analyzing TCP dumps i can see that conversation goes as this:
client request
server ack
server push
server fin, ack (sent after ~0.000020 secs after previous push)
As the result my code can't get data sent by the server, (i'm guessing because of the small delay after push POLLHUP event might go before POLLIN?)
Trying to mimic the problem I've written the following code:
(It mimics the client behaviour on my side)
client:
import time
import socket
from errno import EAGAIN
from select import poll, POLLIN, POLLPRI, POLLERR, POLLHUP, POLLNVAL
def main(buf=""):
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.setblocking(False)
client.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
client.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
polling_object = poll()
polling_object.register(client, POLLPRI | POLLIN | POLLERR | POLLHUP)
in_buf = ""
sock_closed = False
try:
client.connect(("127.0.0.1", 8877))
except socket.error, e:
pass
while True and not sock_closed:
events = polling_object.poll(0)
for _, e in events:
if e & (POLLIN | POLLPRI):
while True:
try:
data = client.recv(1024)
if data:
in_buf += data
elif data == "":
client.close()
sock_closed = True
break
except socket.error, e:
if e.args[0] == EAGAIN:
break
else:
raise
elif e & (POLLERR|POLLHUP|POLLNVAL):
client.close()
sock_closed = True
if buf and not sock_closed:
try:
b_sent = client.send(buf)
if b_sent == len(buf):
buf = ""
else:
buf = buf[b_sent:]
except socket.error, e:
if e.args[0] != EAGAIN:
client.close()
sock_closed = True
time.sleep(0.5)
if sock_closed:
return in_buf
if __name__ == '__main__':
import sys
if len(sys.argv) > 1:
buf = sys.argv[1]
else:
buf = 'hello'
print main(buf)
server
import datetime
import time
import socket
def main():
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server.bind(("127.0.0.1", 8877))
server.listen(0)
client, _ = server.accept()
t1 = time.time()
data = ""
while not data:
data += client.recv(1024)
print "recv data %s" % data
client.sendall('{"ok": 1}')
t2 = time.time()
client.close()
t3 = time.time()
server.close()
return t1, t2, t3
if __name__ == '__main__':
c_r, d_s, c_c = main()
print "Connection received at ", datetime.datetime.fromtimestamp(c_r)
print "All Data sent after %.12f secs" % (d_s - c_r)
print "Connection closed after %.12f secs" % (c_c - d_s)
Running this code won't help me reproduce the problem because my client still can get data from socket buffer, which is kind of obviously by just following the code. The only difference is that in tcp dump it goes like this:
client request
server ack
server push
client ack
server fin, ack
I'm wondering is there a way to send fin, ack right after push without "letting" client to sent ack? Can it be done using python?

Socket.close() doesn't close the Socket

I'm trying to develop a very simple client/server program, the server part is working properly but I've a problem with the client part but I can't understand why.
The client's work is very simple, just retrive the counter value from a external device, then I'm trying to send the retrieved data to the server part.
At the beginning the socket is working well, but some time when I should send the data I've got the server exception and after that the Client is not working.
I can't understand if the s.close() function is working properly.
UPDATE: the exception that I got is "errno 110 connection timed out"
Client:
import time, socket, struct, array, json
import Client_Axis
import sys
import serial
import os
import datetime
import re
import packet
import Config_mio
usbport = '/dev/ttyAMA0'
h = "/r/n"
if __name__=="__main__":
"""Main function that starts the server"""
curr_value = "0000000000"
prev_value = ""
line = '111111111111111'
error_counter = 0
people_in = 0
people_out = 0
txtDate = ""
no_updates_counter = 0
while True:
ser = None
try:
# print('1')
ser = serial.Serial('/dev/ttyAMA0', 9600, timeout=1)
# ser.open()
# print('2')
for line in ser.read():
line = ser.readline()
print(line[6:10])
curr_value = line
except:
print('Serial error')
# print('3')
pass
finally:
if ser:
ser.close()
try:
error_counter += 1
# print('1')
response = Client_Axis.Read_Axis_Camera_Occupancy()
content = response.split(",")
people_in_refresh = int(re.search(r'\d+', content[3]).group())
people_out_refresh = int(re.search(r'\d+', content[4]).group())
# print('2')
error_flag = 0
if people_in != people_in_refresh or people_out != people_out_refresh:
people_in = people_in_refresh
people_out = people_out_refresh
try:
# Creates TCP socket in the specified IP address and port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# Connect client to the server
s.connect((Config_mio.IP_Server_Add, Config_mio.ws_port))
# Create message and send it to server
timestamp = str(time.time())
# msg = packet("c", timestamp, Config_mio.RbPi_Id, content[3], content[4], None)
msg = "c"+","+str(timestamp)+","+str(Config_mio.RbPi_Id)+","+str(people_in)+","+str(people_out)+","+"None"
# json_message = json.dumps(msg)
# s.send(json_message)
s.send(msg)
print "messaggio INVIATO"
# Close connection when data is sent
#s.close()
except:
print('Server connection error 1')
pass
finally:
s.close()
#AXIS_occup_old = AXIS_occup
#AXIS_occup = response.read()
#my_dict = json.loads(AXIS_occup)
# print(AXIS_occup)
# print(my_dict)
#del my_dict["timestamp"]
#AXIS_occup = my_dict
#error_counter = 0
# print('3')
except:
error_msg = "Error retrieving occupancy from: " + Config_mio.IP_AXIS_Add
error_flag = 1
if (error_flag == 1):
no_updates_counter = 0
print "Error detected: %s \r\n" % error_msg
print error_counter
if (error_counter > 200):
os.system("sudo reboot")
elif (line[6:10] != '1111' and prev_value != curr_value):
try:
# Creates TCP socket in the specified IP address and port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# Connect client to the server
s.connect((Config_mio.IP_Server_Add, Config_mio.ws_port))
# Create message and send it to server
timestamp = str(time.time())
msg = "r"+","+str(timestamp)+","+str(Config_mio.RbPi_Id)+","+"None"+","+"None"+","+str(line[6:10])
#msg = {"Id": raspberry_id,
# "Ranging": line[6:10],
# "timestamp": timestamp}
#json_message = json.dumps(msg)
#s.send(json_message)
s.send(msg)
print "Message : %s" % msg
# Close connection when data is sent
s.close()
except:
print('Server connection error 2')
pass
else:
no_updates_counter += 1
# Send message despite there are no changes in value
# This is a heartbeat message of 10 min
if (no_updates_counter > 200):
no_updates_counter = 0
AXIS_occup = ""
prev_value = curr_value
# Reboot device every day - routine
# We have 4 cases incase we miss few seconds
txtDate = str(datetime.datetime.fromtimestamp(time.time()))
if (txtDate[11:19] == "00:00:00"):
os.system("sudo reboot")
if (txtDate[11:19] == "00:00:01"):
os.system("sudo reboot")
if (txtDate[11:19] == "00:00:02"):
os.system("sudo reboot")
if (txtDate[11:19] == "00:00:03"):
os.system("sudo reboot")
# Kill time - 1 sec: Remove it for high speed localisation
time.sleep(1)
Server:
import socket
import json
import time
import Config_mio
import packet
import sqlite3 as lite
if __name__ == "__main__":
"""Main function that starts the server"""
# Creates TCP socket in the specified IP address and port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((Config_mio.IP_Server_Add, Config_mio.ws_port))
# Starts server, up to 10 clients are queued
s.listen(Config_mio.Max_Num_Clients)
while True:
conn, addr = s.accept()
#print "sono dopo ascolto"
msg = conn.recv(1024)
print "Data value:",msg
msg = msg.split(",")
if msg[0] == "c":
print "counter msg"
elif msg[0] == "r":
print "range msg",msg[1],msg[2],msg[5]
conn.close()

Python socket can't receive data

I'm writing interprocess communication using localhost sockets in Python 3.2 and testing it on Windows. Here is some test code with a server and a client, sending messages to each other. Strangely, it fails randomly with the RuntimeError error, raised in the receive function, somewhere around the 5th or 10th connection.
#!/usr/bin/python
# -*- coding: utf-8 -*-
import socket
import pickle
import time
import logging
from multiprocessing import Process
def receive(conn):
def ensure_receive(length):
parts = []
received = 0
while received < length:
chunk = conn.recv(length - received)
if not chunk:
raise RuntimeError("Connection broken")
parts.append(chunk)
received += len(chunk)
return b''.join(parts)
lengthString = ensure_receive(8)
serialized = ensure_receive(int(lengthString))
return pickle.loads(serialized)
def send(conn, message):
def ensure_send(message):
sent = 0
while sent < len(message):
sent += conn.send(message[sent:])
# logging.warning("Now sending")
serialized = pickle.dumps(message, 1)
messageLength = len(serialized)
ensure_send("{:8}".format(messageLength).encode('Latin-1'))
ensure_send(serialized)
def client_function(clientLimit):
for index in range(1, clientLimit + 1):
print ("Client", index)
try:
conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
conn.connect(('localhost', 12333))
send(conn, list(range(100000)))
message = receive(conn)
send(conn, list(range(100)))
# time.sleep(0.01)
conn.shutdown(socket.SHUT_WR)
conn.close()
except Exception:
logging.exception("Socket error in client")
def server_function(clientLimit):
newSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
newSocket.bind(('localhost', 12333))
newSocket.listen(16)
for _ in range(clientLimit):
(conn, address) = newSocket.accept()
time.sleep(0.01)
message = receive(conn)
send(conn, list(range(10)))
message = receive(conn)
conn.shutdown(socket.SHUT_WR)
conn.close()
def test(clientLimit):
server = Process(target = server_function, args = (clientLimit,))
server.start()
time.sleep(1)
client = Process(target = client_function, args = (clientLimit,))
client.start()
client.join()
server.join()
if __name__ == "__main__":
test(100)
However, there are no errors if I uncomment time.sleep(0.01) in client_function, or if I change message order a bit.
Is there a way to make it work, without putting in random waits, and allowing for arbitrary protocols?

It is because of conn.shutdown(socket.SHUT_WR) in your server_function. What you need is socket.SHUT_RD, or better yet, get rid of the shutdown() call at all.