I am try to display data that is sent over a socket via an iteration from a loop. The way I have it at the moment isn't working on the Admin client. What should I do to fix my loop? Thank you
Admin thread in the server -
def HandleAdmin(adminSocket,):
global addressList
(c,a) = adminSocket.accept()
ts = ssl.wrap_socket(c, certfile="5cc515_server.crt",
keyfile="5cc515_server.key",
server_side=True,
cert_reqs=ssl.CERT_REQUIRED,
ca_certs="5cc515-root-ca.cer")
if ts.recv(80).decode() == 'Hello\r\n':
ts.send('Admin-Greetings\r\n'.encode())
if ts.recv(80).decode() == 'Who\r\n':
for i in addressList:
ts.send(i.encode())
ts.close()
return
Admin Client
import ssl
import socket
s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
ts = ssl.wrap_socket(s, certfile="100298750.crt",
keyfile="100298750.key",
ca_certs="5cc515-root-ca.cer")
ts.connect(('127.0.0.1', 4001))
ts.send("Hello\r\n".encode())
if ts.recv(80).decode() == "Admin-Greetings\r\n":
print("The players currently online are:\n")
ts.send("Who\r\n".encode())
loop = True
try:
while(loop == True):
if (ts.recv(1000) != Null):
print(ts.recv(1000).decode())
else:
loop = False
ts.close()
except:
pass
The first problem is that you try to do != Null, which will raise a NameError as Null is not valid in python, it's None. You don't see that error because of the raw except. You should only except the errors you are actually expecting.
In addition to that, recv doesn't return None when there is not data or the connection is closed, it returns an empty string.
Then in your loop you call recv twice, throwing away the result of the first call after the comparison. A better way to write your loop would be:
try:
data = ts.recv(1000)
while data:
print(data.decode())
data = ts.recv(1000)
except IOError as e:
pass
finally:
ts.close()
Or, if you want a more pythonic solution, use a function iterator with the empty string as sentinel:
from functools import partial
for data in iter(partial(ts.recv, 1000), b''):
print(data.decode())
Related
The bounty expires in 5 days. Answers to this question are eligible for a +50 reputation bounty.
Haley Mueller wants to draw more attention to this question.
I'm new to Python so this could be a simple fix.
I am using Flask and sockets for this Python project. I am starting the socket on another thread so I can actively listen for new messages. I have an array variable called 'SocketConnections' that is within my UdpComms class. The variable gets a new 'Connection' appended to it when a new socket connection is made. That works correctly. My issue is that when I try to read 'SocketConnections' from outside of the thread looking in, it is an empty array.
server.py
from flask import Flask, jsonify
import UdpComms as U
app = Flask(__name__)
#app.route('/api/talk', methods=['POST'])
def talk():
global global_server_socket
apples = global_server_socket.SocketConnections
return jsonify(message=apples)
global_server_socket = None
def start_server():
global global_server_socket
sock = U.UdpComms(udpIP="127.0.0.1", portTX=8000, portRX=8001, enableRX=True, suppressWarnings=True)
i = 0
global_server_socket = sock
while True:
i += 1
data = sock.ReadReceivedData() # read data
if data != None: # if NEW data has been received since last ReadReceivedData function call
print(data) # print new received data
time.sleep(1)
if __name__ == '__main__':
server_thread = threading.Thread(target=start_server)
server_thread.start()
app.run(debug=True,host='192.168.0.25')
UdpComms.py
import json
import uuid
class UdpComms():
def __init__(self,udpIP,portTX,portRX,enableRX=False,suppressWarnings=True):
self.SocketConnections = []
import socket
self.udpIP = udpIP
self.udpSendPort = portTX
self.udpRcvPort = portRX
self.enableRX = enableRX
self.suppressWarnings = suppressWarnings # when true warnings are suppressed
self.isDataReceived = False
self.dataRX = None
# Connect via UDP
self.udpSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # internet protocol, udp (DGRAM) socket
self.udpSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) # allows the address/port to be reused immediately instead of it being stuck in the TIME_WAIT state waiting for late packets to arrive.
self.udpSock.bind((udpIP, portRX))
# Create Receiving thread if required
if enableRX:
import threading
self.rxThread = threading.Thread(target=self.ReadUdpThreadFunc, daemon=True)
self.rxThread.start()
def __del__(self):
self.CloseSocket()
def CloseSocket(self):
# Function to close socket
self.udpSock.close()
def SendData(self, strToSend):
# Use this function to send string to C#
self.udpSock.sendto(bytes(strToSend,'utf-8'), (self.udpIP, self.udpSendPort))
def SendDataAddress(self, strToSend, guid):
# Use this function to send string to C#
print('finding connection: ' + guid)
if self.SocketConnections:
connection = self.GetConnectionByGUID(guid)
print('found connection: ' + guid)
if connection is not None:
self.udpSock.sendto(bytes(strToSend,'utf-8'), connection.Address)
def ReceiveData(self):
if not self.enableRX: # if RX is not enabled, raise error
raise ValueError("Attempting to receive data without enabling this setting. Ensure this is enabled from the constructor")
data = None
try:
data, _ = self.udpSock.recvfrom(1024)
print('Socket data recieved from: ', _)
if self.IsNewConnection(_) == True:
print('New socket')
self.SendDataAddress("INIT:" + self.SocketConnections[-1].GUID, self.SocketConnections[-1].GUID)
data = data.decode('utf-8')
except WindowsError as e:
if e.winerror == 10054: # An error occurs if you try to receive before connecting to other application
if not self.suppressWarnings:
print("Are You connected to the other application? Connect to it!")
else:
pass
else:
raise ValueError("Unexpected Error. Are you sure that the received data can be converted to a string")
return data
def ReadUdpThreadFunc(self): # Should be called from thread
self.isDataReceived = False # Initially nothing received
while True:
data = self.ReceiveData() # Blocks (in thread) until data is returned (OR MAYBE UNTIL SOME TIMEOUT AS WELL)
self.dataRX = data # Populate AFTER new data is received
self.isDataReceived = True
# When it reaches here, data received is available
def ReadReceivedData(self):
data = None
if self.isDataReceived: # if data has been received
self.isDataReceived = False
data = self.dataRX
self.dataRX = None # Empty receive buffer
if data != None and data.startswith('DIALOG:'): #send it info
split = data.split(':')[1]
return data
class Connection:
def __init__(self, gUID, address) -> None:
self.GUID = gUID
self.Address = address
def IsNewConnection(self, address):
for connection in self.SocketConnections:
if connection.Address == address:
return False
print('Appending new connection...')
connection = self.Connection(str(uuid.uuid4()),address)
self.SocketConnections.append(connection)
return True
def GetConnectionByGUID(self, guid):
for connection in self.SocketConnections:
if connection.GUID == guid:
return connection
return None
As mentioned above. When IsNewConnection() is called in UdpComms it does append a new object to SocketConnections. It's just trying to view the SocketConnections in the app.route that is empty. My plans are to be able to send socket messages from the app.routes
For interprocess communication you may try to use something like shared memory documented here
Instead of declaring your self.SocketConnections as a list = []
you'd use self.SocketConnections = Array('i', range(10)) (you are then limited to remembering only 10 connections though).
How do I flush a socket in python3?
I'm looking to do something like this
def clear_buffer(sock):
try:
while sock.recv(1024): pass
except:
pass
or
def clear_buffer(sock):
while True:
data = sock.recv(1024)
if not data:
break
After attempting to run these two functions neither seem to break the while loop and/or flush out the socket from incoming data. How do I conditionally do something when the socket has stopped receiving data?
while run_network:
recv = True
data = b''
try:
while recv:
try:
packet = socket.recv(10240)
if packet:
data += packet
else:
recv = False
try:
pickle.loads(data)
recv = False
except:
recv = True
except ConnectionResetError:
print(f"{client} has disconnected........")
break
except ConnectionError:
**strong text**
print(f"{client}has a Connection Error.....")
break
I am new to python and trying to create a test bed where I have a TCP half open and TCP half close situations between a client and the server.
Server code:
def recv_end(the_socket):
End='SERVER WRONG MARKER'
total_data=[];data='';got_end=False
while True:
data=the_socket.recv(8192)
if not data: break
if End in data:
total_data.append(data[:data.find(End)])
got_end=True
break
total_data.append(data)
if len(total_data)>1:
#check if end_of_data was split
last_pair=total_data[-2]+total_data[-1]
if End in last_pair:
total_data[-2]=last_pair[:last_pair.find(End)]
total_data.pop()
got_end=True
break
return (got_end,''.join(total_data))
def basic_server(sock):
got=[]
got_end,data = recv_end(sock)
if not got_end:
sock.send('ERROR:no end!') #<--- not possible w/close()
else: sock.sendall(data*2)
sock.shutdown(1)
sock.close()
import socket
Port=4444
def start_server():
sock=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
sock.bind(('',Port))
sock.listen(5)
print 'started on',Port
while True:
newsock,address=sock.accept()
basic_server(newsock)
def send_data(data):
sock=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
sock.connect(('localhost',Port))
print 'connected'
sock.sendall(data+'CLIENT WRONG MARKER')
print 'sent',data
sock.shutdown(1)
print 'shutdown'
result=[]
while True:
got=sock.recv(2)
if not got: break
result.append(got)
sock.close()
return ''.join(result)
if __name__=='__main__':
start_server()
The client code :
import socket
def send_data(data):
sock=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
sock.connect(('localhost',Port))
print 'connected'
sock.sendall(data+'CLIENT WRONG MARKER')
print 'sent',data
sock.shutdown(1)
print 'shutdown'
result=[]
while True:
got=sock.recv(2)
if not got: break
result.append(got)
sock.close()
return ''.join(result)
def shut_serv_end():
data=('a1234','b1234','c1234','d1234','e1234')
for d in data:
print shut_srv.send_data(d)
I am trying to use the shutdown command that has three options: 0 = done receiving, 1 = done sending, 2 = both
In the code above focuses on 1. The code isn't working as expected. Meaning, I don't see half open connections when I do a packet capture. Can anyone please provide some tips or examples of how one to achieve it or what mistake am I doing?
I have a thread that is defined as in a program that continuously reads serial data along with running a UI in wxpython.
dat = Thread(target=receiving, args=(self.ser,))
The method it calls "receiving" runs in an infinite loop
def receiving(ser):
global last_received
buffer = ''
while True:
date = datetime.date.today().strftime('%d%m%Y')
filename1 = str(date) + ".csv"
while date == datetime.date.today().strftime('%d%m%Y'):
buffer = buffer + ser.read(ser.inWaiting())
if '\n' in buffer:
lines = buffer.split('\n')
if lines[-2]:
last_received = lines[-2]
buffer = lines[-1]
print_data =[time.strftime( "%H:%M:%S"), last_received]
try:
with open(filename1, 'a') as fob:
writ = csv.writer(fob, delimiter = ',')
writ.writerow(print_data)
fob.flush()
except ValueError:
with open('errors.log','a') as log:
log.write('CSV file writing failed ' + time.strftime("%H:%M:%S")+' on '+datetime.date.today().strftime('%d/%m/%Y')+'\n')
log.close()
The argument is defined as
class SerialData(object):
def __init__(self, init=50):
try:
serial_list = serialenum.enumerate()
self.ser = ser = serial.Serial(
port=serial_list[0],
baudrate=9600,
bytesize=serial.EIGHTBITS,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
timeout=None,
xonxoff=0,
rtscts=0,
interCharTimeout=None
)
except serial.serialutil.SerialException:
# no serial connection
self.ser = None
else:
dat = Thread(target=receiving, args=(self.ser,))
if not dat.is_alive:
dat.start()
def next(self):
if not self.ser:
# return anything so we can test when Serial Device isn't connected
return 'NoC'
# return a float value or try a few times until we get one
for i in range(40):
raw_line = last_received
try:
return float(raw_line.strip())
time.sleep(0.1)
except ValueError:
# print 'Not Connected',raw_line
time.sleep(0.1)
return 0
Due to a bug in Ubuntu 14.04 the thread hangs after a while. I wanted to periodically check if the thread is alive and start it again if it is not. So I did something like
def on_timer(self):
self.text.SetLabel(str(mul_factor*self.datagen.next()))
if not dat.is_alive():
dat.start()
wx.CallLater(1, self.on_timer)
This runs every second to update the data in UI but also needs to check if the thread is not stopped. But this gives me an error saying "NameError: global name 'dat' is not defined". I also tried referring to the thread using the object name path. But didn't work either.
Can someone help me as to how I can start the thread out of scope?
It seems like you want to replace dat with self.dat. dat only exists in the scope of the __init__ method. I suggest reading up on Python scoping rules.
I would like to ask how to skip the receive function.
def client():
try:
b = bytes.decode(h.recv(1024))
print("The recieved message : ",b)
b1 = str.encode(b)
c.sendall(b1)
h.sendall(b1)
y.sendall(b1)
except Exception:
pass
try:
g = bytes.decode(y.recv(1024))
print("The recieved message : ",g)
g1 = str.encode(g)
c.sendall(g1)
h.sendall(g1)
y.sendall(g1)
except Exception:
pass
So what I need to do is to check if there is a message coming from the client:
If yes, print it and send it.
if no, skip the function go to check with the other clients.
You need the polling mechanism. The simplest is select
import select
def client():
sockets, _, _ = select.select([h, y], [], [])
# If h or y has data, select exits and returns these sockets
for sock in sockets:
try:
data = sock.recv(1024)
if data == '':
# sock was disconnected handle that
continue
# Process data here
except Exception:
continue