Python 字符串通过 sockets 发送两次

Question

I'm improving this GUI-based chatroom script I found online. Right now I've been working on a way to add chat name tags, starting with a server host tag. This is a snip of my code that adds [Server Host] to someone's nickname if a connection with the host's IP is made:

...
for key, value in addresses.items(): # Go through the currently connected addresses...
        if HOST in value: # ...and check if the host's IP is connected.
            name = "[Server Host] " + name # Add chat tag to the beginning of their nickname.
    msg = "%s has joined the chat!" % name
    broadcast(bytes(msg, "utf8"))
    clients[client] = name
...

However, when one joins the chat with the tag, it says [Server Host] [Server Host] somename for example instead of only one tag. Yet when chatting, the tag is just fine.

Why does this happen?

Bonus questions:

• Is it possible to add color to text in the chat, for tags and text for example?
• Every time a client attempts to exit by pressing the exit button on the window, the server's output has a large error message. How do I fix this so it's not annoying?

Here's the code for the server:

from socket import AF_INET, socket, SOCK_STREAM, gethostbyname, gethostname
from threading import Thread


def accept_incoming_connections():
    """Sets up handling for incoming clients."""
    while True:
        client, client_address = SERVER.accept()
        print("%s:%s has connected." % client_address)
        client.send(bytes("Welcome! Type your name and press enter.", "utf8"))
        addresses[client] = client_address
        Thread(target=handle_client, args=(client,)).start()


def handle_client(client):  # Takes client socket as argument.
    """Handles a single client connection."""

    name = str(client.recv(BUFSIZ).decode("utf8"))
    welcome = 'Welcome, %s! To quit, type !quit.' % name
    client.send(bytes(welcome, "utf8"))
    for key, value in addresses.items(): # Go through the currently connected addresses...
        if HOST in value: # ...and check if the host's IP is connected.
            name = "[Server Host] " + name
    msg = "%s has joined the chat!" % name
    broadcast(bytes(msg, "utf8"))
    clients[client] = name
    while True:
            msg = client.recv(BUFSIZ)
            if msg != bytes("!quit", "utf8"):
                broadcast(msg, name + ": ")
            else:
                client.send(bytes("!quit", "utf8"))
                client.close()
                del clients[client]
                broadcast(bytes("%s has left the chat." % name, "utf8"))
                break


def broadcast(msg, prefix=""):  # prefix is for name identification.
    """Broadcasts a message to all the clients."""
    for sock in clients:
        sock.send(bytes(prefix, "utf8")+msg)

        
clients = {}
addresses = {}

HOST = gethostbyname(gethostname())
while True:
    try:
        PORT = int(input("Enter port to run server on: "))
        if PORT > 1024:
            break
        print("Invalid port entered\n")
    except:
        print('Port must be a number > 1024\n')
print("\nServer running on host %s, and on port %s" % (HOST, PORT,))
BUFSIZ = 1024
ADDR = (HOST, PORT)

SERVER = socket(AF_INET, SOCK_STREAM)
SERVER.bind(ADDR)

if __name__ == "__main__":
    SERVER.listen(5)
    print("Waiting for server connection...")
    ACCEPT_THREAD = Thread(target=accept_incoming_connections)
    ACCEPT_THREAD.start()
    ACCEPT_THREAD.join()
    SERVER.close()

And the client:

from socket import AF_INET, socket, SOCK_STREAM
from threading import Thread
import tkinter


def receive():
    """Handles receiving of messages."""
    while True:
        try:
            msg = client_socket.recv(BUFSIZ).decode("utf8")
            msg_list.insert(tkinter.END, msg)
        except OSError:  # Possibly client has left the chat.
            break


def send(event=None):  # event is passed by binders.
    """Handles sending of messages."""
    msg = my_msg.get()
    my_msg.set("")  # Clears input field.
    client_socket.send(bytes(msg, "utf8"))
    if msg == "!quit":
        client_socket.close()
        top.quit()


def on_closing(event=None):
    """This function is to be called when the window is closed."""
    my_msg.set("!quit")
    send()


HOST = input('Enter host: ')
PORT = input('Enter port: ')
if not PORT:
    PORT = 12345
else:
    PORT = int(PORT)

try:
    BUFSIZ = 1024
    ADDR = (HOST, PORT)

    client_socket = socket(AF_INET, SOCK_STREAM)
    client_socket.connect(ADDR)
except:
    print("Couldn't connect - the server may not be up or you had a different problem.")
    exit()


top = tkinter.Tk()
top.title("Chatroom")

messages_frame = tkinter.Frame(top)
my_msg = tkinter.StringVar()  # For the messages to be sent.
scrollbar = tkinter.Scrollbar(messages_frame)  # To navigate through past messages.
# Following will contain the messages.
msg_list = tkinter.Listbox(messages_frame, height=15, width=50, yscrollcommand=scrollbar.set)
scrollbar.pack(side=tkinter.RIGHT, fill=tkinter.Y)
msg_list.pack(side=tkinter.LEFT, fill=tkinter.BOTH)
msg_list.pack()
messages_frame.pack()

entry_field = tkinter.Entry(top, textvariable=my_msg)
entry_field.bind("<Return>", send)
entry_field.pack()
send_button = tkinter.Button(top, text="Send", command=send)
send_button.pack()

top.protocol("WM_DELETE_WINDOW", on_closing)

receive_thread = Thread(target=receive)
receive_thread.start()
tkinter.mainloop()  # Starts GUI execution.

Answer 1

Related to the first question, is because you are not overwriting the var name but concatenating the string instead. Try changing the name of that variable, something like this:

for key, value in addresses.items(): # Go through the currently connected addresses...
        prefix = "[Server Host] "
        if HOST in value: # ...and check if the host's IP is connected.
            prefix += name # Add chat tag to the beginning of their nickname.
    msg = "%s has joined the chat!" % prefix
    broadcast(bytes(msg, "utf8"))
    clients[client] = name

In this way you separate your formatted string from the user name.

Also, if you are using python 3.x I recommend to change:

msg = "%s has joined the chat!" % prefix

for this:

msg = f"{prefix} has joined the chat!"