How to fix: "TypeError: 'bool' object is not subscriptable"

Question

I am currently working with a basic client/server application and implementing a simple RSA / public-key authentication system. I have ran into this error and can not, for the life of me, figure it out.

I am using the latest version of python.

server.py

def getUserData(username):
    global privateKeysFilename
    filename = privateKeysFilename

    with open(filename, "r") as keysFile:
        for line in keysFile:
            line = [token.rstrip("\n") for token in line.split(",")]
            if(username == line[0]):

                if DEBUG:
                    print("\n=== DEBUG\nUser data = %s\n===\n" %(line))

                return line
    return False



def running(self):
    global BUFFER, DEBUG, start, final

    while 1:
        print('Waiting for a connection')
        connection, client_address = self.server_socket.accept()
        connection.send("Successful connection!".encode())

        x = randint(start, final)
        self.fx = function(x)
        connection.send(str(x).encode())

        try:
            # Output that a client has connected
            print('connection from', client_address)
            write_connection()
            # Set the time that the client connected
            start_time = datetime.datetime.now()

            # Loop until the client disconnects from the server
            while 1:
                # Receive information from the client
                userData = connection.recv(BUFFER)

                #data = connection.recv(1024).decode()

                if(userData != "0"):

                    #define split character 
                    ch = ","

                    userData = userData.split(ch.encode())
                    username = userData[0]
                    r = int(userData[1])

                    userData = getUserData(username)

                    e, n = int(userData[1]), int(userData[2])
                    y = modularPower(r, e, n)

                    if DEBUG:
                        print("=== DEBUG\ne = %d\nn = %d\nr = %d\ny = %d\n===\n" %(e, n, r, y))

                    if(self.fx == y):
                        #if authentication passed
                        connection.send("Welcome!!!".encode())
                    else:
                        connection.send("Failure!!!".encode())



                if (userData != 'quit') and (userData != 'close'):
                    print('received "%s" ' % userData)
                    connection.send('Your request was successfully received!'.encode())
                    write_data(userData)
                    # Check the dictionary for the requested artist name
                    # If it exists, get all their songs and return them to the user
                    if userData in self.song_dictionary:
                        songs = ''
                        for i in range(len(self.song_dictionary.get(userData))):
                            songs += self.song_dictionary.get(userData)[i] + ', '
                        songs = songs[:-2]
                        print('sending data back to the client')
                        connection.send(songs.encode())
                        print("Sent", songs)
                    # If it doesn't exist return 'error' which tells the client that the artist does not exist
                    else:
                        print('sending data back to the client')
                        connection.send('error'.encode())
                else:
                    # Exit the while loop
                    break
            # Write how long the client was connected for
            write_disconnection(start_time)
        except socket.error:
            # Catch any errors and safely close the connection with the client
            print("There was an error with the connection, and it was forcibly closed.")
            write_disconnection(start_time)
            connection.close()
            data = ''
        finally:
            if data == 'close':
                print('Closing the connection and the server')
                # Close the connection
                connection.close()
                # Exit the main While loop, so the server does not listen for a new client
                break
            else:
                print('Closing the connection')
                # Close the connection
                connection.close()
                # The server continues to listen for a new client due to the While loop

and here is the output with error:

Traceback <most recent call last>:
    File "server.py", line 165, in running
    e, n = int(userData[1]), int(userData[2])
TypeError: 'bool' object is not subscriptable

Any help would be greatly appreciated! :)

Answer 1

By using userData[n] you are trying to access the nth element in a subscriptable object.

This can be a list, dict, tuple or even a string.

The error you see means that your object userData is neither of the previous mentioned types, and it's a bool ( True or False )

Since it's the result of calling the function getUserData(), I recommend you check the return type of this function and make sure it's of the mentioned types and revise your code logic.

[Update]

By checking the function getUserData() it looks it only returns line if the username is included, if not it returns False which is not handled in the main code.

I suggest this edit to the code to inlclude success status to the return value as follows.

def getUserData(username):
    global privateKeysFilename
    filename = privateKeysFilename

    with open(filename, "r") as keysFile:
        for line in keysFile:
            line = [token.rstrip("\n") for token in line.split(",")]
            if(username == line[0]):

                if DEBUG:
                    print("\n=== DEBUG\nUser data = %s\n===\n" %(line))

                return True, line
    return False, None

And then in your code when you call getUserData() you check for the success first before parsing data like this

userData = getUserData(username)
if userData [0]:
    e, n = int(userData[1]), int(userData[2])
    y = modularPower(r, e, n)
else:
    # Your failure condition