Know if client is connected to the server

Question

I have a client and a server connected through the socket module in python3, on the server side I know when the client is connected, but on the client side I have no message when the client connects and I would like to have this client-side information to make sure that it connected to the server, my code is as follows:

Client:

import socket

host='10.6.4.198 ' # Endereço IP do Servidor
port=4840# Porto de comunicação, deve ser acima de 1024

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
s.connect((host, port))


while True:
    command = input ("Enter your command: ")
    if command =='EXIT':
        #Send EXIT request to other end
        s.send(str.encode(command))
        break
    elif command == 'KILL':
        #Send KILL command
        s.send(str.enconde(command))
        break
    s.send(str.encode(command))
    reply = s.recv(1024)
    print(reply.decode('utf-8'))

s.close()

Server:

import socket


host = '10.6.4.198 ' # Especifica o endereo IP do nosso Servidor
port = 4840 # Porto através do qual se ir realizar a comunicação, porto acima de 1024


stroredValue= "Yo, What's up?" # variável de armazenamento de dados, poderia ser um ficheiro de texto etc.





# Função configuraçãoo do nosso servidor para que possamos chamá-lo 
def setupServer():
    s= socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
    # s= socket(dominio, tipo, protocolo)
    # AF_INET especifica que o dominio pretendido da Internet 
    # SOCK_STREAM  define o tipo pretendido e suportado pelo dominio AF_INET 
    print("Socket Created.")

    # Declaraçãoo de impressão do não funcionamento do socket
    try:
        s.bind((host, port)) # liga o nosso host e porto 
    except socket.error as msg:
        print (msg)
    print ("Socket bind complete.")
    return s
# Funçãoo configuraçãoo da conexão do nosso servidor
def setupConnection():
    s.listen(1)# Permite uma conexão de cada vez.Pode-se alterar o valor par as conexes pretendidas ao mesmo tempo.
    conn, address = s.accept()# Configuraçãoo de conexão e endereçoo e aceitando qualquer que seja a escuta 
    print(" Connected to : " + address[0] + ":" + str(address[1]))#Str(Address[1]) converte o endereço ip para string
    return conn# retorna o valor de conexãoo

def GET():# recupera esse valor armazenado que se especificou anteriormente
    reply = storedValue
    return reply


def REPEAT(dataMessage):
    reply = dataMessage[1]
    return reply



def dataTransfer(conn):
    #A big loop that sendsreceives data until told not to.
    while True:
        #Receive the data
        data = conn.recv(1024)# receive the data
        data = data.decode('utf-8')# descodificação dos dados recebidos em utf-8
        #Split the data such that you separate the command from the rest of the data.
        dataMessage = data.split(' ',1)
        command = dataMessage[0]
        if command =='GET'
            reply = GET()
        elif command == 'REPEAT'
            reply = REPEAT(dataMessage)
        elif command == 'EXIT':
            print("Our client has left us :(")
            break
        elif command == 'KILL':
            print("Our server is shutting down.")
            s.close()
            break
        else:
            reply = 'Unknow Command'
        conn.sendall(str.encode(reply))
        print("Data has been sent!!!!")
    conn.close()



s = setupServer()# chama a funçãoo setupServer

while True:
    try:
        conn=setupConnection()#obtém a conexao
        dataTransfer(conn)
    except:
        break

after inserting the while in got like this, I have tested but it is giving me error:

try:
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as s:
        s.settimeout(5)
        s.connect((host, port))
        print("Client1 connected to the Server")
        while True:
            command = input ("Enter your command: ")
            if command =='EXIT':
                #Send EXIT request to other end
                s.send(str.encode(command))
            break
            elif command == 'KILL':
                #Send KILL command
                s.send(str.enconde(command))
                break
            s.send(str.encode(command))
            reply = s.recv(1024)
            print(reply.decode('utf-8')
                  except socket.timeou as err:
                  print("Client1 isn't possible connected to the Server")
                  s.close()

The mistake he gives me is this:

File "cookieClientTrycatch.py", line 30
    elif command == 'KILL':
       ^
SyntaxError: invalid syntax

I already executed the indentation in the code

Connection of Clients:

Socket Created.
Socket bind complete.
Connected to : 192.168.1.100:58120

the second connected client does not appear

Answer 1

You can define a block Try/catch to capture possible exceptions triggered by the module socket if something goes wrong. For example, if a timeout in connection, the exception socket.timeout will be fired.

For example:

try:
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) as s:

        # Aguarda no máximo 5 segundos pela conexão
        s.settimeout(5)

        # Tenta fazer a conexão com o servidor
        s.connect((host, port))

        # Tudo certo, prosseguir com o código...
        print('Parabéns! Você está conectado')

except socket.timeout as err:
    print('Não foi possível conectar ao servidor:', err)

Other exceptions can be triggered at different times of the module, so see documentation and adjust the code to your need.