Pythonはsocketを使いますTCPは小さいファイルのダウンロード機能を実現します。

import socket
 
# 1.     
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# 2.    
server.bind(('127.0.0.1', 7890))
# 3.        
server.listen(4)
while True:
  # 4.       
  s_new, addr = server.accept()
  print('  【{}】      ！！'.format(addr[0]))
  while True:
    # 5.    
    try:
      #                  
      recv_data = s_new.recv(1024).decode('utf-8')
      if recv_data:
        print('  【{}】        ： 【{}】'.format(addr[0], recv_data))
        # 6.    
        try:
          f = open(recv_data, 'rb')
          content = f.read()
          send_data = s_new.send(content)
          f.close()
          print('    ！')
        except Exception as result:
          send_data = s_new.send('Non'.encode('utf-8'))
          print('         ')
      else:
        print('        ！')
        break
    except Exception as res:
      print('        ！')
      break
  s_new.close()
# 7，     
server.close()

import socket
#      
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#   IP  
s.connect(('127.0.0.1', 7890))
while True:
 
  #     
  send_data = str(input('           ：'))
  if send_data == 'exit':
    print('     ！')
    break
  s.send(send_data.encode('utf-8'))
 
  #     
  recv_data = s.recv(2048)
  if recv_data == 'Non'.encode('utf-8'):
    print('         ！')
  else:
    with open('【new】' + send_data, 'wb') as f:
      f.write(recv_data)
      print('[{}]    ！'.format(send_data))
      f.close()
 
#      
s.close()