python實現HTTP代理的思路和Demo

一、首先什么是代理：

　　代理其實就是中間轉發的那個玩意，所以在代碼邏輯上也是如此的。

二、Python寫http代理的基本邏輯：

　　（1）接受瀏覽器發出的請求，解析，拼湊成該有的樣子，然后使用套接字發出去。

　　（2）完了，其實Demo就這么簡單。

三、下面講講如何接受瀏覽器發起的請求，其實只要是請求就可以，沒必要是瀏覽器的。外部發來的請求一樣OK哦。

#接受請求就是一個服務器，沒毛病老鐵。所以用到了一個庫BaseHTTPServer

#-*- coding:utf-8 -*-

#import lib-file
import urllib
import socket
from BaseHTTPServer import BaseHTTPRequestHandler,HTTPServer 

#define handler function class
class MyHandler(BaseHTTPRequestHandler):
    #HTTP method GET (e.x.)
    def do_GET(self):
        url = self.path
        print "url:",url
        protocol,rest = urllib.splittype(url)
        print "protocol:",protocol
        host,rest = urllib.splithost(rest)
        print "host:",host
        path = rest
        print "path:",path
        host,port = urllib.splitnport(host)
        print "host:",host
        port = 80 if port < 0 else port
        host_ip = socket.gethostbyname(host)
        print (host_ip,port)
        #above easy to understand
        del self.headers['Proxy-Connection']
        print self.headers
        self.headers['Connection'] = 'close'
        #Above! Three lines code removes Proxy-Connection columns and set connection to close to make sure no keep-alive link
        #Bottom! Lines make request like what we see in the burpsuite!
        send_data = 'GET ' + path + ' ' + self.protocol_version + '\r\n'
        head = ''
        for key, val in self.headers.items():
            head = head + "%s: %s\r\n" % (key, val)
        send_data = send_data + head + '\r\n'
        print send_data
        #
        client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        client.connect((host_ip,port))
        client.send(send_data)
        #while True:
        #    ret = server.recv(4096)
        #    print ret
        data = ''
        while True:
            tmp = client.recv(4096)
            if not tmp:
                break
            data = data + tmp

        # socprint data
        client.close()
        self.wfile.write(data)

看邏輯很簡單，利用basehttpserver 收請求socket轉發

起main函數：

def main():
    try:
        server = HTTPServer(('127.0.0.1', 8888), MyHandler)
        print 'Welcome to the machine...'
        server.serve_forever()
        print "testend"
    except KeyboardInterrupt:
        print '^C received, shutting down server'
        server.socket.close()

if __name__ == '__main__':
    main()

這里可以看到已經ok了，但是由於百度那邊跳轉和阻塞，還是沒能成功完成代理，不過數據包確確實實轉發出去了，但是代碼邏輯已經ok。

參考：

http://www.lyyyuna.com/2016/01/16/http-proxy-get1/