如何从UDP服务器发送UDP消息而不自行发送？

Question

I'd like to make a UDP server that sends a message to a UDP client soon after the server gets the message from the client. I'm using Python and Google Protobuffer as a message protocol.

Currently, the message receiving part seems working, but regarding the message sending part, it has an issue: the response message from the server doesn't arrive the client and even worse, the server shows that message (maybe it sends to itself? Right now, the console shows both the message from client and the message that should be sent to client). This issue didn't happen when I tried the similar code on C++ or C#.

The followings are some excerpt from my code:

def connect(self):
     remote = ('x.x.x.x',xxxx) #ip and port
     self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
     self.sock.settimeout(2.5)
     self.sock.bind(remote)
     self.sock.settimeout(None)

def start(self):
    while not self.exit_thread:

        # Get the message from client
        data, address = self.sock.recvfrom(8192)

        if data is not None:

            # De-serialize inbound message from client
            msg_client = xxx_pb2.msgClient()
            msg_client.ParseFromString(data)

            # Display message from client
            self.display_inbound_message(msg_client)

            # Create a new message from server
            msg_serer = xxx_pb2.msgServer()
            self.create_outbound_message(msg_serer)

            # Send the Udp message to the client, return the number of bytes sent
            bytes_sent = self.sock.sendto(msg_server.SerializeToString(), self.remote)
            if (bytes_sent < 0):
                print("Error send message")

I don't have enough experience for UDP programming on Python. Please let me know if you notice anything.

Answer 1

The issue with this code is that the server replies to itself, rather than the remote client. In here:

data, address = self.sock.recvfrom(8192)
# ...
bytes_sent = self.sock.sendto(msg_server.SerializeToString(), self.remote)

It should be:

bytes_sent = self.sock.sendto(msg_server.SerializeToString(), address)

It makes good sense to rename remote to server_address because it is this server's address.