Build proxy server for Python

Wonderful work demand

The user has an internal system to provide basic data. The user wants to encrypt the content of the data file (TXT) without changing the internal system, and then copy it to our system

Train of thought

Imagine a proxy server that intercepts a user’s download request, parses the content and returns an encrypted file

reference

www.cnblogs.com/yyds/p/7072…

Concrete implementation code

import logging; logging.basicConfig(level=logging.INFO) import socket, select import _thread from io import BytesIO from Cryptodome.Cipher import AES class Proxy(object): def __init__(self, soc): self.client, _ = soc.accept() self.target = None self.is_export = False self.BUFSIZE = 1024 self.method = None self.targetHost = None  self.s = None# request parsing
    def getClientRequest(self):
        request = self.client.recv(self.BUFSIZE).decode()
        if not request:
            return None
        cn = request.find('\n')
        firstLine = request[:cn]
        line = firstLine.split()
        self.method = line[0]
        self.targetHost = line[1]
        return request

    Intercept normal requests
    def commonMethod(self, request):
        tmp = self.targetHost.split('/')
        logging.info(tmp)
        targetAddr = self.getTargetInfo(tmp[2])
        if len(tmp) > 5 and tmp[5].find('export_delivery') >= 0:
            self.is_export = True
        else:
            self.is_export = False
        try:
            (fam, _, _, _, addr) = socket.getaddrinfo(targetAddr[0], targetAddr[1])[0]
        except Exception as e:
            print(e)
            return
        self.target = socket.socket(fam)
        self.target.connect(addr)
        self.target.send(request.encode())
        self.nonblocking()

    def connectMethod(self, request):
        print('Establish a connection')
        pass

    Start method
    def run(self):
        request = self.getClientRequest()
        if request:
            if self.method in ['GET'.'POST'.'PUT'.'DELETE'.'HAVE']:
                self.commonMethod(request)
            elif self.method == 'CONNECT':
                self.connectMethod(request)

    # Analyze data
    def nonblocking(self):
        inputs = [self.client, self.target]
        break_flag = False
        if (self.is_export == True):
            self.s = BytesIO()
        while True:
            if break_flag == True:
                break
            readable, writeable, errs = select.select(inputs, [], inputs, 3)
            if errs:
                print('nonblocking errs')
                break
            for soc in readable:
                data = soc.recv(self.BUFSIZE)
                if data:
                    if soc is self.client:
                        self.target.send(data)
                    elif soc is self.target:
                        if (self.is_export == True):
                            self.s.write(data)
                        else:
                            self.client.send(data)
                else:
                    break_flag = True
                    break
        if (self.is_export == True):
            self.parseRequest()
        self.client.close()
        self.target.close()

    Parse the file contents and encrypt them
    def parseRequest(self):
        try:
            _res = self.s.getvalue().decode("gb2312")
            tmp = _res.split('octet-stream\r\n\r\n')
            _h = tmp[0] + 'octet-stream\r\n\r\n'
            _b = tmp[1]
            nb = BytesIO()
            nb.write(_h.encode('utf8'))
            secret_key = "ThisIs SecretKey"
            iv_param = 'This is an IV456'
            aes1 = AES.new(secret_key.encode("gb2312"), AES.MODE_CFB, iv_param.encode("gb2312"))
            cipher_data = aes1.encrypt(_b.encode("gb2312"))
            nb.write(cipher_data)
            self.client.send(nb.getvalue())
        except Exception as e:
            print('Error:', e)
            self.client.send(self.s.getvalue())

    def getTargetInfo(self, host):
        port = 0
        site = None
        if ':' in host:
            tmp = host.split(':')
            site = tmp[0]
            port = int(tmp[1])
        else:
            site = host
            port = 80
        return site, port


if __name__ == '__main__':
    host = '127.0.0.1'
    port = 8083
    backlog = 5
    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server.bind((host, port))
    server.listen(backlog)
    while True:
        # multithreaded
        # t = Process(target=Proxy(server).run)
        # t.start()
        # single thread
        _thread.start_new_thread(Proxy(server).run, ())
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