Develop Reference

Python client socket not receiving data from TCP server

I'm trying to build a fake money transfer program with sockets in python. Everything is working perfectly except the "name" and "amount" transfer from the server to the client. When someone clicks receive on the client interface, the server is supposed to send the client the name of the person who sent the money and the amount. The problem is that the client is not receiving the data sent from the server. When you click the "receive" button, the interface just freezes then crashes. From the debugging I've done, I'm pretty sure the server is sending the name and amount, but the client is not receiving it. I honestly have no idea why it's not working. Everything I did should work like it has numerous other times throughout the program. This one has got me stumped.
Any help would be great. Thanks! 😁
[CODE]
Server.py:
import socket
import threading
HOST = '192.168.1.6'
PORT = 9090
def client_fun(client, addr):
global transfers
print(f"{addr} just connected!")
connected = True
while connected:
msg = client.recv(1024).decode('utf-8')
if msg == "RECEIVE_CHECK":
usrn = client.recv(1024).decode('utf-8')
transfers_ = open("transfers.txt", "r")
transfers = str(transfers_.readlines())
transfers = transfers.split("+")
transfers[0] = transfers[0].replace("[", "")
transfers[0] = transfers[0].replace("'", "")
transfers.pop()
names = []
for tran in transfers:
tran_ = tran.split("-")
i = 0
while i <= len(tran):
names.append(tran_[2])
i += 1
if usrn in names:
client.send("OK".encode('utf-8'))
else:
client.send("NO".encode('utf-8'))
if usrn in names:
for tran in transfers:
tran_ = tran.split("-")
if usrn == tran_[2]:
name = str(tran_[0])
amount = str(tran_[1])
client.send(name.encode('utf-8'))
client.send(amount.encode('utf-8'))
account_file = usrn + "_" + "account.txt"
account_r = open(account_file, "r")
account_r = str(account_r.readlines())
account_r = account_r.replace(']', '')
account_r = account_r.replace('[', '')
account_r = account_r.replace("'", "")
try:
account_r = int(account_r)
except:
print("Can't Convert Str to Int!")
break
new_amount = int(tran_[1]) + account_r
account_w = open(account_file, "w")
account_w.write(str(new_amount))
account_w.close()
tran = tran + "+"
transFers_ = open("transfers.txt", "r")
transFers = str(transFers_.readlines())
transFers_.close()
transFers = transFers.replace(']', '')
transFers = transFers.replace('[', '')
transFers = transFers.replace("'", "")
transFers = transFers.replace(tran, '')
transFers_ = open("transfers.txt", 'w+')
transFers_.write(transFers)
transFers_.close()
print("Excepted!")
else:
print("Nothing Here!")
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind((HOST, PORT))
server.listen()
print("Server is listening!")
while True:
c_socket, address = server.accept()
thread = threading.Thread(target=client_fun, args=(c_socket, address))
thread.start()
Client.py:
import socket
HOST = '192.168.1.6'
PORT = 9090
socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
def receive(usrn):
socket.send("RECEIVE_CHECK".encode('utf-8'))
socket.send(usrn.encode('utf-8'))
c = socket.recv(1024).decode('utf-8')
if c == "OK":
try:
print("Trying to except....")
name = socket.recv(2000).decode('utf-8')
amount = socket.recv(2000).decode('utf-8')
print("Excepted!")
messagebox.showwarning("Continue?", f"{name} has sent you ${amount}", icon="question")
messagebox.showwarning("Info", f"${amount} has just been transferred to your account!", icon="info")
menu(usrn)
except:
print("Error!")
else:
print("Nothing Today!")

How can I monitor client side inputs and send input requests from server every 5 seconds if no input is received?

I want to set up tcp server and client where server monitors client input and sends a request every 3 seconds if no input is received. Then client replies with its time. This goes on in an infinite loop. Also, they both have an option to exit the infinite loop. I don't know how to add the exit functionality as send(), recv() and input() block the code execution.
I have tried using select with 3 second timeout, it didn't work. I have tried threading but it stops after first user input until the next user input. I want it to go infinitely unless user wants to exit.
Infinite loop for communication:
client side:
while True:
data = ClientSocket.recv(1024).decode()
print("From Server: " + str(data))
# clear string
data = ''
data = 'Random Number: ' + str(random.randint(1, 101))
current_time = datetime.now()
required_format = (current_time.strftime("Date: %Y-%m-%d\tTime: %H:%M:%S.%f")[:-3])
data = data + "\t" + required_format + '\n'
ClientSocket.send(data.encode())
print("Sending: " + str(data))
data = ''
Server Side:
while True:
data = ''
data = 'Please enter a response.'
print("Sending: " + str(data))
ClientSocket.send(data.encode())
# clear string
data = ''
data = ClientSocket.recv(1024).decode()
print("From Client: " + str(data))
Select function that i tried:
readlist = [ClientSocket]
incoming = select.select(readlist, [], [], 3)
if incoming:
#perform a chat function here
else:
#use the code mentioned above for automated messages
This is the threading feature that I tried:
Python 3 Timed Input
How can I restrict time for recv(), send() and input() while sending and receiving message request and acknowledgements?
Please let me know if you would like to see the full code.

Something like this should work for you
server.py
inputs = [server]
outputs = []
messages = {}
try:
while inputs:
readable, writable, error = select.select(inputs, outputs, [])
for sock in readable:
if sock is server:
client, _ = sock.accept()
inputs.append(client)
messages[client] = Queue()
else:
data = sock.recv(1024).decode()
if data and data != 'exit\n':
print(data)
messages[sock].put(data)
if sock not in outputs:
outputs.append(sock)
else:
print('Client disconnected')
sock.close()
inputs.remove(sock)
for sock in outputs:
try:
msg = messages[sock].get_nowait()
sock.send(msg.upper().encode())
except Empty:
sleep(3)
sock.send(b'No data recieved')
outputs.remove(sock)
except KeyboardInterrupt:
server.close()
client.py
inputs = [sock, sys.stdin]
while inputs:
readable, _, _ = select.select(inputs, [], [])
for s in readable:
if s is sock:
data = sock.recv(1024).decode()
if data:
if data.lower() != 'exit':
print('{}'.format(data))
sys.stdout.write('You: ')
sys.stdout.flush()
else:
exiting('Server')
else:
exiting('Server')
else:
msg = sys.stdin.readline()
sock.send(msg.encode())
sys.stdout.write('You: ')

python sockets, trying to make a log in interaction betwen server and client

Hello so i have my server with a database (dictironay) and another passworddatabase
import socket
import sys
from _thread import *
host = ""
port = 8000
serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print("Socket Created")
try:
serversocket.bind((host, port))
except socket.error as e:
print(str(e))
sys.exit()
database = {"name1" :{"hair" : "red", "size" : 1.50}}
password_database = {"name1": "1234",
"name2": "4321"}
def client_thread(conn): #threader client
welcome = "Welcome to the server. Type something and hit enter \n"
conn.send(welcome.encode("UTF-8"))
login(conn)
while True: # NOT IMPORTANT KEEP READING
data = conn.recv(24)
reply = data.decode("UTF-8")
if reply == "1":
menu1 = "Menu 1: Buy \n"
conn.send(menu1.encode("UTF-8"))
else:
wrong = "wrong option \n"
conn.send(wrong.encode("UTF-8"))
def login(conn): #MY LOGIC PROBLEM IS HERE
log = "Log in MENU: \n"
logi = log.encode("UTF-8")
conn.send(logi)
us = "Username: \n"
use = us.encode("UTF-8")
conn.send(use)
userr = conn.recv(24)
user = userr.decode("UTF-8")
pa = "Password: \n"
pasw = pa.encode("UTF-8")
conn.send(pasw)
passr = conn.recv(24)
passw = passr.decode("UTF-8")
tries = 0
while tries < 3:
if user in passwordDictionary and passwordDictionary[user] == passw:
print("Logged in")
menu()
else:
print("Wrong Username Or Password \n")
tries += 1
print("You failed the login too many times, blocking you out")
conn.close()
while 1: # NOT IMPORTANT
conn, addr = serversocket.accept()
print("Connected with " + addr[0] + ":" + str(addr[1]))
start_new_thread(client_thread, (conn, ))
serversocket.close()
Whats working:
The server is working fine, i'm having troubles doing the login on the client side.
client.py ==> client DOESNT go into the if data == Log in menu
is there a better way to do this?
#! /usr/bin/python3
import socket
clientsocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
clientsocket.connect(('localhost', 8000))
print("Connected")
datae = clientsocket.recv(24)
data = datae.decode("UTF-8")
clientsocket.send(datae)
while data != "!q":
if data == "Log in MENU: \n":
usere = input()
user = usere.encode("UTF-8")
clientsocket.send(user)
What would be the best way to create an log in interaction with the server?
the server has the usernames and passwords, i need to log in and then i need to edit the database depending on what user was chossen, but i'm having a hard time doing the algorithm

theres problems with the code you provided... however ill assume it actually works for you somehow and rather than copy paste you manually typed it
you are recieveing the first message here
datae = clientsocket.recv(24)
data = datae.decode("UTF-8") # GOT A MESSAGE
You then have the message datae = b'Welcome to the server. '
which does not match "Log in MENU: \n", and data != "!q" so it goes back into your loop and checks if data == "Log in MENU: \n" it doesnt so it repeats ... but you never get the next message instead try something like this second message
data = ""
while data != "!q":
if data == "Log in MENU: \n":
usere = input()
user = usere.encode("UTF-8")
clientsocket.send(user)
data = clientsocket.recv(24).decode("UTF-8") # GET THE NEXT MESSAGE!
but even then you are going to have problems because your server continues to write so you will get something like "Log in MENU: \nUsername" or something .... basically you need to work out a better message passing scheme than recv(24)

To avoid Errors try using a header with something like 64 Bytes wich always is the first message send. This Header is then used to send the actual length of the following message to the server. For example:
def send_response(conn, msg):
message = msg.encode(FORMAT)
send_length = len(str(len(message)).encode(FORMAT))
res_len = bytes(len(message)) + (b' ' * (HEADER - send_length))
print(f"[SENDING MESSAGE] {msg}")
conn.send(res_len)
conn.send(response)

Chat Client/Server problems on Python

Me and a friend of mine are doing a chat room with python, basically he's doing the server part and I'm doing the GUI and Client part, I don't know why the app just stop to work without any reason showing the Windows message "Python is not responding"
This is the Server code:
#max name length=9999
#max message types=100
#max groupmsg recipients = 9999
#max msg length =8191 characters
import socket
import threading
import sys
def find_users(): #Continously Searches For New Clients
while True:
user, client_address = connector.accept()
threading.Thread(target=new_user, args=(user,)).start()
def new_user(identity):
while True:
print(identity)
name_length=identity.recv(4).decode() #max user name length =9999
username=identity.recv(int(name_length)).decode()
password=identity.recv(8192).decode()
if username in user_details and password == user_details[username]: #correct credentials
client_details[usename]=identity
identity.sendall('y'.encode())
break
elif username in user_details: #incorrect password
print('Please Re-enter The User Details')
identity.sendall('n'.encode())
else: #New user
user_details[username]=password
client_details[username]=identity
identity.sendall('y'.encode())
break
pubmsg(username+' has connected')
active_users.append(username)
identity.settimeout(5)
try:
while True: #waits for incoming messages
msgtype= identity.recv(2).decode() #identifies message type, max types =100
if msgtype == '01': #public message
communication = identity.recv(8192).decode()
pubmsg(str(username + ' >>> ' + communication))
elif msgtype == '02': #private message
direction=[]
recipno=identitiy.recv(4) #defines max group msg recipients
for y in range(0,recipno): #repeats once per recipient
recip_name_length=identity.recv(4).decode()
recip_name=identity.recv(recip_name_length).decode()
direction.append(recip_name)
gmsg=identity.recv(8192).decode()
groupmsg(gmsg,direction)
except Exception as e:
active_users.remove(username)
del client_details[username]
pubmsg(username+' disconnected')
identity.close()
sys.exit()
def pubmsg(Group_message):
print(Group_message)
for person in client_details:
client_details[person].sendall(Group_message.encode())
def groupmsg(Direct_message,recipients,sender):
gmsg=sender +' (to '
for person in recipients: #repeats once per recipient
gmsg+=person+', '
gmsg=gmsg.rstrip(', ')
gmsg=gmsg + ')' + ' >>> ' + Direct_message
for person in recipients:
client_details[person].sendall(gmsg)
user_details={}
client_details={}
active_users=[]
connector = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print ('Launching Server')
connector.bind(('localhost', 5000)) #Links socket to server address
connector.listen(10)
threading.Thread(target=find_users).start()
For the client and the GUI I'm putting here only the function called by the button "Connect" of the GUI (the ones that are creating problems), the GUI uses the QT Libraries
This is the code called by the button:
def client_connect(self):
ip_address = str(self.ipText.toPlainText())
port = int(self.portText.toPlainText())
nickname = self.nameText.toPlainText()
password = 'hello'
connect = threading.Thread(target = connection_thread, args = (ip_address, port, nickname, password))
connect.start()
This is the thread function:
def connection_thread(address, port, nickname, password):
nickname = nickname.encode()
password = password.encode()
while True:
try:
c = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
c.connect((address, port))
c.sendall('{0:0=4d}'.format(len(nickname)).encode())
c.sendall(nickname)
c.sendall(password)
answr = c.recv(2).decode()
if answr == 'y':
msg_box("CONNECTED", "Now you are connected to the server.")
while True:
time.sleep(2)
c.sendall('03'.encode())
message_received =c.recv(8192).decode()
self.chatList.addItem(message_received)
except Exception as e:
msg_box("CONNECTION FAILED", "Connection to server failed, try again.")
break
From the server code the connection of my client arrives but, the client stop working without showing the msg_box that says that we are connected.

When you say connect.join() you wait for the thread connect to finish, but it is in an infinite loop, so it is not done until the connection closes.

python Client hangs when no data to receive from server and hangs in that thread w/o letting client send

I am trying to figure out how to get my client to send and receive data 'simultaneously' and am using threads. My problem is that, depending on the way I set it up, the way here it waits for data from the server in the recieveFromServer function which is in its own thread and cannot stop it when nothing will be sent. The other way it just waits for user input, and will send to the server and then I'd call the function recieveFromServer after the client sends a message to the server which doesn't allow for fluent communication, but cannot get it to alternate automatically. How do I release the thread when the client has nothing to be sent, or there is no more to be received from the server.
It would get to long if I tried to explain everything I have tried. :)
Thanks.
The client:
from socket import *
from threading import *
import thread
import time
from struct import pack,unpack
from networklingo import *
#from exception import *
HOST = '192.168.0.105'
PORT = 21567
BUFFSIZE = 1024
ADDR = (HOST,PORT)
lock = thread.allocate_lock()
class TronClient:
def __init__(self,control=None):
self.tcpSock = socket(AF_INET,SOCK_STREAM)
#self.tcpSock.settimeout(.2)
self.recvBuff = []
def connect(self):
self.tcpSock.connect(ADDR)
self.clientUID = self.tcpSock.recv(BUFFSIZE)
print 'My clientUID is ', self.clientUID
t = Thread(target = self.receiveFromSrv())
t.setDaemon(1)
t.start()
print 'going to main loop'
self.mainLoop()
#t = Thread(target = self.mainLoop())
#t.setName('mainLoop')
#t.setDaemon(1)
#t.start()
def receiveFromSrv(self):
RECIEVING = 1
while RECIEVING:
#print 'Attempting to retrieve more data'
#lock.acquire()
#print 'Lock Aquired in recieveFromSrv'
#try:
data = self.tcpSock.recv(BUFFSIZE)
#except socket.timeout,e:
#print 'Error recieving data, ',e
#continue
#print data
if not data: continue
header = data[:6]
msgType,msgLength,clientID = unpack("hhh",header)
print msgType
print msgLength
print clientID,'\n'
msg = data[6:]
while len(msg) < msgLength:
data = self.tcpSock.recv(BUFFSIZE)
dataLen = len(data)
if dataLen <= msgLength:
msg += data
else:
remLen = msgLength-len(data) #we just need to retrieve first bit of data to complete msg
msg += data[:remLen]
self.recvBuff.append(data[remLen:])
print msg
#else:
#lock.release()
# print 'lock release in receiveFromSrv'
#time.sleep(2)
#RECIEVING = 0
def disconnect(self,data=''):
self.send(DISCONNECT_REQUEST,data)
#self.tcpSock.close()
def send(self,msgType,msg):
header = pack("hhh",msgType,len(msg),self.clientUID)
msg = header+msg
self.tcpSock.send(msg)
def mainLoop(self):
while 1:
try:
#lock.acquire()
#print 'lock aquired in mainLoop'
data = raw_input('> ')
except EOFError: # enter key hit without any data (blank line) so ignore and continue
continue
#if not data or data == '': # no valid data so just continue
# continue
if data=='exit': # client wants to disconnect, so send request to server
self.disconnect()
break
else:
self.send(TRON_CHAT,data)
#lock.release()
#print 'lock released in main loop'
#self.recieveFromSrv()
#data = self.tcpSock.recv(BUFFSIZE)
#t = Thread(target = self.receiveFromSrv())
#t.setDaemon(1)
#t.start()
if __name__ == "__main__":
cli = TronClient()
cli.connect()
#t = Thread(target = cli.connect())
#t.setName('connect')
#t.setDaemon(1)
#t.start()
The server (uses a lock when incrementing or decrementing number of clients):
from socket import *
from threading import *
import thread
from controller import *
from networklingo import *
from struct import pack,unpack
HOST = ''
PORT = 21567
BUFSIZE = 1024
ADDR = (HOST,PORT)
nclntlock = thread.allocate_lock()
class TronServer:
def __init__(self,maxConnect=4,control=None):
self.servSock = socket(AF_INET,SOCK_STREAM)
# ensure that you can restart server quickly when it terminates
self.servSock.setsockopt(SOL_SOCKET,SO_REUSEADDR,1)
self.servSock.bind(ADDR)
self.servSock.listen(maxConnect)
# keep track of number of connected clients
self.clientsConnected = 0
# give each client a unique identfier for this run of server
self.clientUID = 0
# list of all clients to cycle through for sending
self.allClients = {}
# keep track of threads
self.cliThreads = {}
#reference back to controller
self.controller = control
self.recvBuff = []
def removeClient(self,clientID,addr):
if clientID in self.allClients.keys():
self.allClients[clientID].close()
print "Disconnected from", addr
nclntlock.acquire()
self.clientsConnected -= 1
nclntlock.release()
del self.allClients[clientID]
else:
print 'ClientID is not valid'
def recieve(self,clientsock,addr):
RECIEVING = 1
# loop serving the new client
while RECIEVING: # while PLAYING???
try:
data = clientsock.recv(BUFSIZE)
except:
RECIEVING = 0
continue
# if not data: break #no data was recieved
if data != '':
print 'Recieved msg from client: ',data
header = data[:6]
msgType,msgLength,clientID = unpack("hhh",header)
print msgType
print msgLength
print clientID,'\n'
if msgType == DISCONNECT_REQUEST: #handle disconnect request
self.removeClient(clientID,addr)
else: #pass message type and message off to controller
msg = data[6:]
while len(msg) < msgLength:
data = self.tcpSock.recv(BUFSIZE)
dataLen = len(data)
if dataLen <= msgLength:
msg += data
else:
remLen = msgLength-len(data) #we just need to retrieve first bit of data to complete msg
msg += data[:remLen]
self.recvBuff.append(data[remLen:])
print msg
# echo back the same data you just recieved
#clientsock.sendall(data)
self.send(TRON_CHAT,msg,-1) #send to client 0
for k in self.allClients.keys():
if self.allClients[k] == clientsock:
self.removeClient(k,addr)
print 'deleted after hard exit from clientID ', k
#self.cliThreads[k].join()
#del self.cliThreads[k]
# then tell controller to delete player with k
break
def send(self,msgType,msg,clientID=-1):
header = pack("hhh",msgType,len(msg),clientID)
msg = header+msg
if clientID in self.allClients:
self.allClients[clientID].send(msg)
elif clientID==ALL_PLAYERS:
for k in self.allClients.keys():
self.allClients[k].send(msg)
def mainLoop(self):
global nclntlock
try:
while self.controller != None and self.controller.state == WAITING:
print 'awaiting connections'
clientsock, caddy = self.servSock.accept()
nclntlock.acquire()
self.clientsConnected += 1
nclntlock.release()
print 'Client ',self.clientUID,' connected from:',caddy
clientsock.setblocking(0)
clientsock.send(str(self.clientUID))
self.allClients[self.clientUID] = clientsock
t = Thread(target = self.recieve, args = [clientsock,caddy])
t.setName('recieve-' + str(self.clientUID))
self.cliThreads[self.clientUID] = t
self.clientUID += 1
# t.setDaemon(1)
t.start()
finally:
self.servSock.close()
if __name__ == "__main__":
serv = TronServer(control = LocalController(nPlayers = 3, fWidth = 70, fHeight = 10))
t = Thread(target = serv.mainLoop())
t.setName('mainLoop')
# t.setDaemon(1)
t.start()

I think you want to try and set the socket to non-blocking mode:
http://docs.python.org/library/socket.html#socket.socket.setblocking
Set blocking or non-blocking mode of
the socket: if flag is 0, the socket
is set to non-blocking, else to
blocking mode. Initially all sockets
are in blocking mode. In non-blocking
mode, if a recv() call doesn’t find
any data, or if a send() call can’t
immediately dispose of the data, a
error exception is raised; in blocking
mode, the calls block until they can
proceed. s.setblocking(0) is
equivalent to s.settimeout(0);
s.setblocking(1) is equivalent to
s.settimeout(None).
Also, instead of using raw sockets, have you considdered using the multiprocessing module. It is a higher-level abstraction for doing network IO. The section on Pipes & Queues is specific to sending and receiving data between a client/server.