Socket.Accept永远占用，并且无阻塞返回错误

Question

I am having trouble running a code that simply connects to my own IP address. The socket.send function works just fine, but the socket.accept takes too long to run. Can somebody help me? This is probably a simple answer I haven't seen yet, as I'm only 13.

I've checked if the port is correct by scanning for it with another code, and I've run it on the python IDLE and in Mac terminal. I've tried 'www.google.com','localhost','','127.0.0.1', and my personal IP address, yet socket.accept still doesn't work

code: scanner code, returns 20000, AKA it didn't find a port

import socket
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);
for port in range(0,20001):
    try:
        s.setblocking(False)
        s.bind(('127.0.0.1',port))
        s.listen(1);
        c,addr=s.accept()
        break
    except:
        if port%1000==0:
            print(port)

accept code:

import socket
s=socket.socket(socket.AF_UNIX,socket.SOCK_DGRAM);
s.setblocking(False)
s.bind(('127.0.0.1',20000))
s.listen(1);
c,addr=s.accept()

I want the accept code to return nothing, and the scanner to return a number from 0-20000. This is my first post on Stack-overflow, so please tell me what to do better on my next post (:

Answer 1

This line is incorrect for receiving an incoming TCP connection:

s=socket.socket(socket.AF_UNIX,socket.SOCK_DGRAM);

It should instead be:

s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);

Also, s.setblocking(False) is probably not something you want to do, since you probably want accept() to block until an incoming TCP connection has been received.

Update: in addition to the problem above, the other problem is that the alleged port-scanning code posted in the question doesn't actually scan any ports, since it doesn't ever attempt to make an outgoing TCP connection. For reference, here is a version of that code that actually tries to connect to ports 0-20000 on localhost and then prints out which ports it was able to make a connection to:

import socket

connectedPorts = []
for port in range(0,20001):
    s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);
    try:
        s.connect(('127.0.0.1',port))
        print("Connect succeeded on port %i" % port)
        connectedPorts.append(port)
    except Exception as e:
        print "Port %i: %s" % (port, e)
    s.close()

print("")
print("Connect succeeded on the following ports: ", connectedPorts)

... and for completeness, here is the working accept-on-port-20000 code:

import socket

s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);
s.bind(('127.0.0.1',20000))
s.listen(1);
print("Calling accept...")
c,addr=s.accept()
print("Accept returned: [%s, %s]" % (c,addr))