python socket學習

一、簡單實例：

實現客戶端向服務端發送的信息，服務器收到信息後加上當前時間再返回給客戶端

服務端實現：

#!/usr/bin/python
import socket, traceback, time
host = ''
port = 8000
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))
s.listen(1)
while 1:
    try:
        clientsock, clientaddr = s.accept()
    except KeyboardInterrupt:
        raise
    except:
        traceback.print_exc()
        continue
    try:
        print "Got connection from", clientsock.getpeername()
        while 1:
            data = clientsock.recv(4096)
            if not len(data):
                break
            clientsock.sendall("[%s] %s" % (time.ctime(),data))
    except (KeyboardInterrupt, SystemExit):
        raise
    except:
        traceback.print_exc()
try:
    clientsock.close()
except KeyboardInterrupt:
    raise
except:
    traceback.print_exc()

客戶端實現：

#!/usr/bin/pythonh
import socket, ssl
host = '192.168.209.128'
port = 8000
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
while True:
        data = raw_input('please input data:')
        if not data:
                break
        s.sendall(data)
        data = s.recv(4096)
        print data
ssl_sock.close()

運行測試：

[root@localhost example]# python echoclient1.py

please input data:test python

[Sun Sep 15 14:38:47 2013] test python

please input data:test 1111111111111111111111

[Sun Sep 15 14:38:52 2013] test 1111111111111111111111

please input data:

二、socket 多任務處理

以上代碼要實現的功能是實現了，但是當你用多個客戶端同時執行向服務器端發送信息的時候，就發現同一時間服務端只能處理一個連接，其他的無法正常返回。這是因爲服務端的單線程實現的，當收到一個客戶端請求處理的時候，就會進入阻塞狀態，無法同時處理多個任務。

爲了能夠同時爲多個客戶端服務，需要能夠同時處理多個網絡連接的方法。可通過三種方法來實現：

forking、threading和異步I/O。

通過threading實現服務端：

#!/usr/bin/python
import socket, traceback, os, sys, time
from threading import *
host = ''
port = 8000
def handlechild(clientsock):
        print "New child", currentThread().getName()
        print "Got connection from", clientsock.getpeername()
        while 1:
                data = clientsock.recv(4096)
                if not len(data):
                        break
                clientsock.sendall("[%s] %s" % (time.ctime(),data))
        clientsock.close()
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR,1)
s.bind((host, port))
s.listen(1)
while 1:
        try:
                clientsock, clientaddr = s.accept()
        except KeyboardInterrupt:
                raise
        except:
                traceback.print_exc()
                continue
        t = Thread(target = handlechild, args = [clientsock])
        t.setDaemon(1)
        t.start()

這樣就可以讓服務器同時處理多個任務了。

三、在服務端和客戶端使用ssl

首先創建一個自簽名證書：

openssl req -new -x509 -days 365 -nodes -out cert.pem -keyout cert.key

服務端：

#!/usr/bin/python
import socket, ssl, traceback, threading, sys, time
host = ''
port = 443
def Myhandlechild(clientsock):
        print "New child", threading.currentThread().getName()
        print "Got connection from", clientsock.getpeername()
        while 1:
                data = clientsock.recv(4096)
                if not len(data):
                        break
                clientsock.sendall("[%s] %s" % (time.ctime(),data))
        clientsock.close()
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))
s.listen(5)
while 1:
        try:
                clientsock, clientaddr = s.accept()
                connsock = ssl.wrap_socket(clientsock, server_side=True,
                                           certfile="cert.pem", keyfile="cert.key")
        except KeyboardInterrupt:
                raise
        except:
                traceback.print_exc()
                continue
        t = threading.Thread(target = Myhandlechild, args = [connsock])
        t.setDaemon(1)
        t.start()

客戶端：

#!/usr/bin/pythonh
import socket, ssl
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
ssl_sock = ssl.wrap_socket(s,ca_certs="cert.pem", cert_reqs = ssl.CERT_REQUIRED)
ssl_sock.connect(('127.0.0.1', 443))
while 1:
        data = raw_input('input data:')
        if not data:
                break
        ssl_sock.sendall(data)
        data = ssl_sock.recv(4096)
        print data
ssl_sock.close()