HostnameEchoServer

Another simple example of sockets. The server.py runs a server on port 1026. Opening a TCP socket to this port and reading it returns the hostname of the server. The massclient.py uses threads for each machine on a /24 subnet, and it gets the subnet using the connect 8.8.8.8 trick to avoid getting the answer of localhost. (Interestingly ChatGPT kept giving me code that returned the IP for localhost.)

client.py

import socket
from icecream import ic
import sys
import re

args = sys.argv[1:]

def make_local(n):
  s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  s.connect(("8.8.8.8", 80))
  x = s.getsockname()[0]
  s.close()
  xs = x.split(".")
  xs[-1] = str(n)
  return ".".join(xs)

def do_arg(arg):
  if m := re.match(r"(\d+\.){3}\d+$",arg):
    ip = arg
  elif arg.isnumeric():
    ip = make_local(arg)
  else:
    ip = arg
  s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  try:
    s.connect((ip,1026))
    data = s.recv(1024)
    print(ip,data.decode())
  except ConnectionRefusedError:
    print(ip,"#Connection Refused")
  except TimeoutError:
    print(ip,"#Timeout")
  except Exception as e:
    ic(e)

for arg in args:
  do_arg(arg)

massclient.py

import socket
from icecream import ic
import sys
import re
import threading

args = sys.argv[1:]

def make_local(n):
  s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  s.connect(("8.8.8.8", 80))
  x = s.getsockname()[0]
  s.close()
  xs = x.split(".")
  xs[-1] = str(n)
  return ".".join(xs)

def do_arg(arg):
  if m := re.match(r"(\d+\.){3}\d+$",arg):
    ip = arg
  elif arg.isnumeric() or type(arg) is int:
    ip = make_local(arg)
  else:
    ip = arg
  s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  s.settimeout(0.5)
  try:
    s.connect((ip,1026))
    data = s.recv(1024)
    return data.decode()
  except TimeoutError:
    return None
  except ConnectionRefusedError:
    return None
  except Exception as e:
    ic(e)
    return None

def get_name_task(idx):
  ip = make_local(idx)
  result = do_arg(ip)
  if result is not None:
    found[ip] = result

found = {}
threads = []
for i in range(2,254):
  thread = threading.Thread(target=get_name_task,args=(i,))
  threads.append(thread)
  thread.start()

for thread in threads:
  thread.join()

for ip, name in found.items():
  print(ip,name)

server.py

import socket
import threading

def hostname():
  return socket.gethostname()

def handle_client(client_socket):
  client_socket.send(hostname().encode())
  client_socket.close()

def main():
  host = "0.0.0.0"
  port = 1026
  try:
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.bind((host,port))
    server_socket.listen()

    while True:
      client_socket, client_address = server_socket.accept()
      client_thread = threading.Thread(target=handle_client, args=(client_socket,))
      client_thread.start()
  except Exception as e:
    ic(2)
  finally:
    server_socket.close()

if __name__ == main():
  main()