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  • cookie

    1、基本操作

    Cookie是由服务器端生成,发送给User-Agent(一般是浏览器),浏览器会将Cookie的key/value保存到某个目录下的文本文件内,下次请求同一网站时就发送该Cookie给服务器(前提是浏览器设置为启用cookie)

    在后台设置cookie:

    class IndexHanlder(tornado.web.RequestHandler):
        def get(self):
            print(self.cookies) #获取http请求中携带的浏览器中的所有cookie
            print(self.get_cookie("k1"))  # 获取浏览器中的cooki
            self.set_cookie("k1","v1")  #为浏览器设置cookie
    

    在前端(浏览器上使用JavaScript):

    document.cookie               #获取浏览器中所有的cookie
    document.cookie.split(";")   #获取浏览器中具体某一个cookie,需要先分割,再操作
    document.cookie = "k1=999"   #设置cookie
    

    由于Cookie保存在浏览器端,所以在浏览器端也可以使用JavaScript来操作Cookie:

    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
    <h1>123</h1>
    </body>
    <script>
    /*设置cookie,指定秒数过期*/
    function setCookieBySeconds(name,value,expires){
        var current_date = new Date();  //获取当前时间
        current_date.setSeconds(current_date.getSeconds() + expires);
        document.cookie = name + "= "+ value +";expires=" + current_date.toUTCString();
    }
    /*设置cookie,指定天数过期*/
    function setCookieByDays(name,value,expires){
        var current_date = new Date();  //获取当前时间
        current_date.setDate(current_date.getDate() + expires);
        document.cookie = name + "= "+ value +";expires=" + current_date.toUTCString();
    }
    </script>
    </html>
    

    2、加密cookie(签名)

    Cookie 很容易被恶意的客户端伪造。加入你想在 cookie 中保存当前登陆用户的 id 之类的信息,你需要对 cookie 作签名以防止伪造。Tornado 通过 set_secure_cookie 和 get_secure_cookie 方法直接支持了这种功能。 要使用这些方法,你需要在创建应用时提供一个密钥,名字为 cookie_secret。 你可以把它作为一个关键词参数传入应用的设置中: 

    def _create_signature_v1(secret, *parts):
        hash = hmac.new(utf8(secret), digestmod=hashlib.sha1)
        for part in parts:
            hash.update(utf8(part))
        return utf8(hash.hexdigest())
    
    # 加密
    def _create_signature_v2(secret, s):
        hash = hmac.new(utf8(secret), digestmod=hashlib.sha256)
        hash.update(utf8(s))
        return utf8(hash.hexdigest())
    
    def create_signed_value(secret, name, value, version=None, clock=None,
                            key_version=None):
        if version is None:
            version = DEFAULT_SIGNED_VALUE_VERSION
        if clock is None:
            clock = time.time
    
        timestamp = utf8(str(int(clock())))
        value = base64.b64encode(utf8(value))
        if version == 1:
            signature = _create_signature_v1(secret, name, value, timestamp)
            value = b"|".join([value, timestamp, signature])
            return value
        elif version == 2:
            # The v2 format consists of a version number and a series of
            # length-prefixed fields "%d:%s", the last of which is a
            # signature, all separated by pipes.  All numbers are in
            # decimal format with no leading zeros.  The signature is an
            # HMAC-SHA256 of the whole string up to that point, including
            # the final pipe.
            #
            # The fields are:
            # - format version (i.e. 2; no length prefix)
            # - key version (integer, default is 0)
            # - timestamp (integer seconds since epoch)
            # - name (not encoded; assumed to be ~alphanumeric)
            # - value (base64-encoded)
            # - signature (hex-encoded; no length prefix)
            def format_field(s):
                return utf8("%d:" % len(s)) + utf8(s)
            to_sign = b"|".join([
                b"2",
                format_field(str(key_version or 0)),
                format_field(timestamp),
                format_field(name),
                format_field(value),
                b''])
    
            if isinstance(secret, dict):
                assert key_version is not None, 'Key version must be set when sign key dict is used'
                assert version >= 2, 'Version must be at least 2 for key version support'
                secret = secret[key_version]
    
            signature = _create_signature_v2(secret, to_sign)
            return to_sign + signature
        else:
            raise ValueError("Unsupported version %d" % version)
    
    # 解密
    def _decode_signed_value_v1(secret, name, value, max_age_days, clock):
        parts = utf8(value).split(b"|")
        if len(parts) != 3:
            return None
        signature = _create_signature_v1(secret, name, parts[0], parts[1])
        if not _time_independent_equals(parts[2], signature):
            gen_log.warning("Invalid cookie signature %r", value)
            return None
        timestamp = int(parts[1])
        if timestamp < clock() - max_age_days * 86400:
            gen_log.warning("Expired cookie %r", value)
            return None
        if timestamp > clock() + 31 * 86400:
            # _cookie_signature does not hash a delimiter between the
            # parts of the cookie, so an attacker could transfer trailing
            # digits from the payload to the timestamp without altering the
            # signature.  For backwards compatibility, sanity-check timestamp
            # here instead of modifying _cookie_signature.
            gen_log.warning("Cookie timestamp in future; possible tampering %r",
                            value)
            return None
        if parts[1].startswith(b"0"):
            gen_log.warning("Tampered cookie %r", value)
            return None
        try:
            return base64.b64decode(parts[0])
        except Exception:
            return None
    
    
    def _decode_fields_v2(value):
        def _consume_field(s):
            length, _, rest = s.partition(b':')
            n = int(length)
            field_value = rest[:n]
            # In python 3, indexing bytes returns small integers; we must
            # use a slice to get a byte string as in python 2.
            if rest[n:n + 1] != b'|':
                raise ValueError("malformed v2 signed value field")
            rest = rest[n + 1:]
            return field_value, rest
    
        rest = value[2:]  # remove version number
        key_version, rest = _consume_field(rest)
        timestamp, rest = _consume_field(rest)
        name_field, rest = _consume_field(rest)
        value_field, passed_sig = _consume_field(rest)
        return int(key_version), timestamp, name_field, value_field, passed_sig
    
    
    def _decode_signed_value_v2(secret, name, value, max_age_days, clock):
        try:
            key_version, timestamp, name_field, value_field, passed_sig = _decode_fields_v2(value)
        except ValueError:
            return None
        signed_string = value[:-len(passed_sig)]
    
        if isinstance(secret, dict):
            try:
                secret = secret[key_version]
            except KeyError:
                return None
    
        expected_sig = _create_signature_v2(secret, signed_string)
        if not _time_independent_equals(passed_sig, expected_sig):
            return None
        if name_field != utf8(name):
            return None
        timestamp = int(timestamp)
        if timestamp < clock() - max_age_days * 86400:
            # The signature has expired.
            return None
        try:
            return base64.b64decode(value_field)
        except Exception:
            return None
    
    
    def get_signature_key_version(value):
        value = utf8(value)
        version = _get_version(value)
        if version < 2:
            return None
        try:
            key_version, _, _, _, _ = _decode_fields_v2(value)
        except ValueError:
            return None
    
        return key_version
    View Code

    五、Session(依赖于cookie)

    由于cookie中需要保存客户的很多信息,而且如果信息很多的话,服务端与客户端交互的时候也浪费流量,所以我们需要用很少的一段字符串来保存很多的信息,这就是我们所要引进的session。

    cookie 和session 的区别:

    1、cookie数据存放在客户的浏览器上,session数据放在服务器上。

    2、cookie不是很安全,别人可以分析存放在本地的COOKIE并进行COOKIE欺骗    考虑到安全应当使用session。

    3、session会在一定时间内保存在服务器上。当访问增多,会比较占用你服务器的性能    考虑到减轻服务器性能方面,应当使用COOKIE。

    4、单个cookie保存的数据不能超过4K,很多浏览器都限制一个站点最多保存20个cookie。

    5、所以个人建议:    将登陆信息等重要信息存放为SESSION    其他信息如果需要保留,可以放在COOKIE中

      (1)利用session实现用户验证

    #!/usr/bin/env python
    # -*- coding:utf-8 -*-
    import tornado.web
    import tornado.ioloop
    import hashlib
    import time
    li = {}
    class IndexHanlder(tornado.web.RequestHandler):
        def get(self):
            obj = hashlib.md5()
            obj.update(bytes(str(time.time()),encoding="utf-8"))
            random_str = obj.hexdigest()
            li[random_str]={}
            li[random_str]["k1"]=123
            li[random_str]["k2"]=456
            li[random_str]["is_login"]=True
            self.set_cookie("qqqqqq",random_str)
            self.write("成功设置cookie")
        def post(self, *args, **kwargs):
            pass
    
    class ManagerHanlder(tornado.web.RequestHandler):
        def get(self):
            random_str = self.get_cookie("qqqqqq",None)
            current_user_info = li.get(random_str,None)
            if not current_user_info:
                self.redirect("/index")
            else:
                if li[random_str]["is_login"]:
                    self.write("欢迎")
                else:
                    self.redirect("/index")
            def post(self, *args, **kwargs):
                pass
    
    settings={
        "template_path":"tpl",
         "static_path":"st",
        "cookie_secret":"123"
    }
    
    class IndeHanlder(tornado.web.RequestHandler):
        def get(self):
            self.render("1.html")
    application = tornado.web.Application([
        (r"/index", IndexHanlder),
        (r"/manager", ManagerHanlder),
    ],**settings)
    
    if __name__ == "__main__":
        application.listen(8888)
        tornado.ioloop.IOLoop.instance().start()
    

     (2)利用session验证用户精简版

    #!/usr/bin/env/python
    # -*- coding:utf-8 -*-
    import tornado.web
    
    container = {}
    # container = {
    #     # "第一个人的随机字符串":{},
    #     # "第一个人的随机字符串":{'k1': 111, 'parents': '你'},
    # }
    
    class Session:
        def __init__(self, handler):
            self.handler = handler
            self.random_str = None
    
        def __genarate_random_str(self):
            import hashlib
            import time
            obj = hashlib.md5()
            obj.update(bytes(str(time.time()), encoding='utf-8'))
            random_str = obj.hexdigest()
            return random_str
    
        def __setitem__(self, key, value):
            # 在container中加入随机字符串
            # 定义专属于自己的数据
            # 在客户端中写入随机字符串
            # 判断,请求的用户是否已有随机字符串
            if not self.random_str:
                random_str = self.handler.get_cookie('__kakaka__')
                if not random_str:
                    random_str = self.__genarate_random_str()
                    container[random_str] = {}
                else:
                    # 客户端有随机字符串
                    if random_str in container.keys():
                        pass
                    else:
                        random_str = self.__genarate_random_str()
                        container[random_str] = {}
                self.random_str = random_str 
    
            container[self.random_str][key] = value
            self.handler.set_cookie("__kakaka__", self.random_str)
    
        def __getitem__(self, key):
            # 获取客户端的随机字符串
            # 从container中获取专属于我的数据
            #  专属信息【key】
            random_str =  self.handler.get_cookie("__kakaka__")
            if not random_str:
                return None
            # 客户端有随机字符串
            user_info_dict = container.get(random_str,None)
            if not user_info_dict:
                return None
            value = user_info_dict.get(key, None)
            return value
    class BaseHandler(tornado.web.RequestHandler):
        def initialize(self):
            self.session = Session(self)
    class IndexHandler(BaseHandler):
        def get(self):
            if self.get_argument('u',None) in ['alex','eric']:
                self.session['is_login'] = True
                self.session['name'] =self.get_argument('u',None)
                print(container)
            else:
                self.write('请你先登录')
    class MangerHandler(BaseHandler):
        def get(self):
            val = self.session['is_login']
            if val:
                self.write(self.session['name'])
            else:
                self.write('登录失败')
    class LoginHandler(BaseHandler):
        def get(self,*args,**kwargs):
            self.render('login.html',status="")
        def post(self, *args, **kwargs):
            user = self.get_argument('user',None)
            pwd = self.get_argument('pwd',None)
            code = self.get_argument('code',None)
            check_code = self.session['CheckCode']
            if code.upper() == check_code.upper():
                self.write('验证码正确')
            else:
                self.render('login.html',status ='验证码错误')
    class CheckCodeHandler(BaseHandler):
        def get(self,*args,**kwargs):
            import io
            import check_code
            mstream = io.BytesIO()
            img, code = check_code.create_validate_code()
            img.save(mstream,'GIF')
            self.session['CheckCode']=code
            self.write(mstream.getvalue())
    class CsrfHandler(BaseHandler):
        def get(self,*args,**kwargs):
            self.render("csrf.html")
        def post(self, *args, **kwargs):
            self.write("hahahahaah")
    
    settings = {
        'template_path':'views',
        'static_path':'static',
        "xsrf_cookies":True
    }
    application = tornado.web.Application([
        (r'/index',IndexHandler),
        (r'/manger',MangerHandler),
        (r'/login',LoginHandler),
        (r'/check_code',CheckCodeHandler),
        (r'/csrf',CsrfHandler),
    ],**settings)
    
    if __name__ == "__main__":
        application.listen(8888)
        tornado.ioloop.IOLoop.instance().start()
    

      

     

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  • 原文地址:https://www.cnblogs.com/guokaixin/p/5832190.html
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