Network Proramming in Python

socket.socket() returns socket object: _socketobject Most of socket API are methods on socket objects or functions Value result arguments (e.g., socket address) become return val-ues Socket address is a tuple: (host, port) sendall == writen() in UNP

Echo Client and Iterative Server

Echo Server using I/O Multi-plexing주의 : File 은 Windows 에서 select() 할 수 없다 .

Echo Server with Class Impl.

SocketServer (socketserver in Python 3)A Framework for Network ServerIterative Multi-threads Processes

BaseServer ThreadingMixIn ForkingMixIn

TCPServer ThreadingTCPServer ForkingTCPServer

UnixStreamServer ThreadingUnixStreamServer ForkingUnixStreamServer

UDPServer ThreadingUDPServer ForkingUDPServer

UnixDatagram-Server

ThreadingUnixDatagram-Server

ForkingUnixDatagram-Server

Class Inheritance

BaseRequestHandler

StreamRequestHandler Support file-like methods- self.rfile: buffered- self.wfile: unbuffered

DatagramRe-questHandler

Support StringIO- self.rfile and self.wfil

Server Classes Inheritance

Handler Classes Inheritance

server = ThreadingTCPServer((‘’, port)), StreamRequestHandler)server.serve_forever()

handle() method 만 작성하면 충분 !!

Running Server

SocketServer Classes Skele-ton

Request Handler Skelton

Threaded Servers with Request Handler

thread module (_thread in Python 3)◦ Low-level thread use threading module

threading module: object-oriented way on the thread module◦ Define target function ◦ or write subclass of Thread overriding run() method

Threads in Python

Thread Functions and Subclassesimport timefrom threading import Thread

def sleeper(i): print "thread %d sleeps for 5 seconds" % i time.sleep(5) print "thread %d woke up" % i

for i in range(10): t = Thread(target=sleeper, args=(i,)) t.start()

import threading, zipfile

class AsyncZip(threading.Thread): def __init__(self, infile, outfile): threading.Thread.__init__(self) self.infile = infile self.outfile = outfile def run(self): f = zipfile.ZipFile(self.outfile, 'w', zipfile.ZIP_DEFLATED) f.write(self.infile) f.close() print 'Finished background zip of: ', self-.infile

background = AsyncZip('mydata.txt', 'myarchive.zip')background.start()print 'The main program continues to run in fore-ground.'

background.join() # Wait for the background task to finishprint 'Main program waited until background was done.'

Override run() method

Threaded Echo Client

Lock, Rlock, Condition, Semaphore, BoundedSemapore objectsimport threading

some_lock = threading.Lock()

with some_lock: print "some_rlock is locked while this executes"

Queue: A synchronized queue classdef worker(): while True: item = q.get() do_work(item) q.task_done()

q = Queue()for i in range(num_worker_threads): t = Thread(target=worker) t.daemon = True t.start()

for item in source(): q.put(item)

q.join() # block until all tasks are done

Internet Access>>> import urllib2>>> for line in urllib2.urlopen('http://tycho.usno.navy.mil/cgi-bin/timer.pl'):... if 'EST' in line or 'EDT' in line: # look for Eastern Time... print line

<BR>Nov. 25, 09:43:32 PM EST

>>> import smtplib>>> server = smtplib.SMTP('localhost')>>> server.sendmail('soothsayer@example.org', 'jcaesar@example.org',... """To: jcaesar@example.org... From: soothsayer@example.org...... Beware the Ides of March.... """)>>> server.quit()

struct — Interpret strings as packed binary dataimport structsource_ip = '192.168.1.101'dest_ip = '192.168.1.1' # or socket.gethostbyname('www.google.com') # ip header fieldsip_ihl = 5ip_ver = 4ip_tos = 0ip_tot_len = 0  # kernel will fill the correct total lengthip_id = 54321   #Id of this packetip_frag_off = 0ip_ttl = 255ip_proto = socket.IPPROTO_TCPip_check = 0    # kernel will fill the correct checksumip_saddr = socket.inet_aton ( source_ip )   #Spoof the source ip address if you want toip_daddr = socket.inet_aton ( dest_ip ) ip_ihl_ver = (version << 4) + ihl # the ! in the pack format string means network orderip_header = struct.pack('!BBHHHBBH4s4s' , ip_ihl_ver, ip_tos, ip_tot_len, ip_id, ip_frag_off, ip_ttl, ip_proto, ip_check, ip_saddr, ip_daddr)