使用Python将JSON对象发送到TCP侦听器端口

Question

I have a listener on a tcp localhost:

HOST = '127.0.0.1'  # The server's hostname or IP address
PORT = 8192         # The port used by the server
def client_socket():
    while 1:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.bind((TCP_IP,TCP_PORT))
        s.listen(1)
        while 1:
            print 'Listening for client...'
            conn, addr = s.accept()
            print 'Connection address:', addr
            data = conn.recv(BUFFER_SIZE)
            if data == ";" :
                conn.close()
                print "Received all the data"
                i=0
                for x in param:
                    print x
                #break
            elif data:
                print "received data: ", data
                param.insert(i,data)
                i+=1
                #print "End of transmission"
        s.close()

I am trying to send a JSON object to the same port on the local host:

HOST = '127.0.0.1'  # The server's hostname or IP address
PORT = 8192         # The port used by the server
def json_message(direction):

    local_ip = socket.gethostbyname(socket.gethostname())
    data = {
        'sender' : local_ip,
        'instruction' : direction
    }

    json_data = json.dumps(data, sort_keys=False, indent=2)
    print("data %s" % json_data)

    send_message(json_data)

    return json_data



def send_message(data):
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.connect((HOST, PORT))
        s.sendall(data)
        data = s.recv(1024)

    print('Received', repr(data))

However, I get a socket error:

socket.error: [Errno 98] Address already in use

What am I doing wrong? Will this work or do I need to serialize the JSON object?

Answer 1

There are a few problems with your code, but the one that will likely address your issue is setting the SO_REUSEADDR socket option with:

s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

after you create the socket (with socket.socket(...) but before you attempt to bind to an address (with s.bind() .

In terms of other things, the two "halves" of the code are pretty inconsistent -- like you copied and pasted code from two different places and tried to use them? (One uses a context manager and Python 3 print syntax while the other uses Python 2 print syntax...)

But I've written enough socket programs that I can decipher pretty much anything, so here's a working version of your code (with some pretty suboptimal parameters eg a buffer size of 1, but how else would you expect to catch a single ; ?)

Server:

import socket

HOST = '127.0.0.1'  # The server's hostname or IP address
PORT = 8192         # The port used by the server
BUFFER_SIZE = 1

def server_socket():
    data = []
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        s.bind((HOST,PORT))
        s.listen()
        while 1: # Accept connections from multiple clients
            print('Listening for client...')
            conn, addr = s.accept()
            print('Connection address:', addr)
            while 1: # Accept multiple messages from each client
                buffer = conn.recv(BUFFER_SIZE)
                buffer = buffer.decode()
                if buffer == ";":
                    conn.close()
                    print("Received all the data")
                    for x in data:
                        print(x)
                    break
                elif buffer:
                    print("received data: ", buffer)
                    data.append(buffer)
                else:
                    break

server_socket()

Client:

import socket
import json

HOST = '127.0.0.1'  # The server's hostname or IP address
PORT = 8192         # The port used by the server

def json_message(direction):
    local_ip = socket.gethostbyname(socket.gethostname())
    data = {
        'sender': local_ip,
        'instruction': direction
    }

    json_data = json.dumps(data, sort_keys=False, indent=2)
    print("data %s" % json_data)

    send_message(json_data + ";")

    return json_data



def send_message(data):
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.connect((HOST, PORT))
        s.sendall(data.encode())
        data = s.recv(1024)

    print('Received', repr(data))

json_message("SOME_DIRECTION")