Django之中间件，csrf跨站伪造请求，auth认证模块

Django请求生命周期

django的中间件

django的中间件相当于保安，请求的时候要经过django的中间件才能连接django的后端

能用来干什么：能够做网站的全局身份认证，访问频率，权限认证，只要是全局的校验都可以用中间件来完成。

django的默认七个中间件

MIDDLEWARE = [
           'django.middleware.security.SecurityMiddleware',
           'django.contrib.sessions.middleware.SessionMiddleware',
           'django.middleware.common.CommonMiddleware',
           'django.middleware.csrf.CsrfViewMiddleware',
           'django.contrib.auth.middleware.AuthenticationMiddleware',
            'django.contrib.messages.middleware.MessageMiddleware',
            'django.middleware.clickjacking.XFrameOptionsMiddleware',
                            ]

class SecurityMiddleware(MiddlewareMixin):
                    def __init__(self, get_response=None):
                        self.sts_seconds = settings.SECURE_HSTS_SECONDS
                        self.sts_include_subdomains = settings.SECURE_HSTS_INCLUDE_SUBDOMAINS
                        self.sts_preload = settings.SECURE_HSTS_PRELOAD
                        self.content_type_nosniff = settings.SECURE_CONTENT_TYPE_NOSNIFF
                        self.xss_filter = settings.SECURE_BROWSER_XSS_FILTER
                        self.redirect = settings.SECURE_SSL_REDIRECT
                        self.redirect_host = settings.SECURE_SSL_HOST
                        self.redirect_exempt = [re.compile(r) for r in settings.SECURE_REDIRECT_EXEMPT]
                        self.get_response = get_response

                    def process_request(self, request):
                        path = request.path.lstrip("/")
                        if (self.redirect and not request.is_secure() and
                                not any(pattern.search(path)
                                        for pattern in self.redirect_exempt)):
                            host = self.redirect_host or request.get_host()
                            return HttpResponsePermanentRedirect(
                                "https://%s%s" % (host, request.get_full_path())
                            )

                    def process_response(self, request, response):
                        if (self.sts_seconds and request.is_secure() and
                                'strict-transport-security' not in response):
                            sts_header = "max-age=%s" % self.sts_seconds
                            if self.sts_include_subdomains:
                                sts_header = sts_header + "; includeSubDomains"
                            if self.sts_preload:
                                sts_header = sts_header + "; preload"
                            response["strict-transport-security"] = sts_header

                        if self.content_type_nosniff and 'x-content-type-options' not in response:
                            response["x-content-type-options"] = "nosniff"

                        if self.xss_filter and 'x-xss-protection' not in response:
                            response["x-xss-protection"] = "1; mode=block"

                        return response
                
                class CsrfViewMiddleware(MiddlewareMixin):
                        if settings.CSRF_USE_SESSIONS:
                            request.session[CSRF_SESSION_KEY] = request.META['CSRF_COOKIE']
                        else:
                            response.set_cookie(
                                settings.CSRF_COOKIE_NAME,
                                request.META['CSRF_COOKIE'],
                                max_age=settings.CSRF_COOKIE_AGE,
                                domain=settings.CSRF_COOKIE_DOMAIN,
                                path=settings.CSRF_COOKIE_PATH,
                                secure=settings.CSRF_COOKIE_SECURE,
                                httponly=settings.CSRF_COOKIE_HTTPONLY,
                            )
                            # Set the Vary header since content varies with the CSRF cookie.
                            patch_vary_headers(response, ('Cookie',))
                    def process_request(self, request):
                        csrf_token = self._get_token(request)
                        if csrf_token is not None:
                            # Use same token next time.
                            request.META['CSRF_COOKIE'] = csrf_token

                    def process_view(self, request, callback, callback_args, callback_kwargs):
                        if getattr(request, 'csrf_processing_done', False):
                            return None

                        # Wait until request.META["CSRF_COOKIE"] has been manipulated before
                        # bailing out, so that get_token still works
                        if getattr(callback, 'csrf_exempt', False):
                            return None

                        # Assume that anything not defined as 'safe' by RFC7231 needs protection
                        if request.method not in ('GET', 'HEAD', 'OPTIONS', 'TRACE'):
                            if getattr(request, '_dont_enforce_csrf_checks', False):
                                # Mechanism to turn off CSRF checks for test suite.
                                # It comes after the creation of CSRF cookies, so that
                                # everything else continues to work exactly the same
                                # (e.g. cookies are sent, etc.), but before any
                                # branches that call reject().
                                return self._accept(request)

                            if request.is_secure():
                                # Suppose user visits http://example.com/
                                # An active network attacker (man-in-the-middle, MITM) sends a
                                # POST form that targets https://example.com/detonate-bomb/ and
                                # submits it via JavaScript.
                                #
                                # The attacker will need to provide a CSRF cookie and token, but
                                # that's no problem for a MITM and the session-independent
                                # secret we're using. So the MITM can circumvent the CSRF
                                # protection. This is true for any HTTP connection, but anyone
                                # using HTTPS expects better! For this reason, for
                                # https://example.com/ we need additional protection that treats
                                # http://example.com/ as completely untrusted. Under HTTPS,
                                # Barth et al. found that the Referer header is missing for
                                # same-domain requests in only about 0.2% of cases or less, so
                                # we can use strict Referer checking.
                                referer = force_text(
                                    request.META.get('HTTP_REFERER'),
                                    strings_only=True,
                                    errors='replace'
                                )
                                if referer is None:
                                    return self._reject(request, REASON_NO_REFERER)

                                referer = urlparse(referer)

                                # Make sure we have a valid URL for Referer.
                                if '' in (referer.scheme, referer.netloc):
                                    return self._reject(request, REASON_MALFORMED_REFERER)

                                # Ensure that our Referer is also secure.
                                if referer.scheme != 'https':
                                    return self._reject(request, REASON_INSECURE_REFERER)

                                # If there isn't a CSRF_COOKIE_DOMAIN, require an exact match
                                # match on host:port. If not, obey the cookie rules (or those
                                # for the session cookie, if CSRF_USE_SESSIONS).
                                good_referer = (
                                    settings.SESSION_COOKIE_DOMAIN
                                    if settings.CSRF_USE_SESSIONS
                                    else settings.CSRF_COOKIE_DOMAIN
                                )
                                if good_referer is not None:
                                    server_port = request.get_port()
                                    if server_port not in ('443', '80'):
                                        good_referer = '%s:%s' % (good_referer, server_port)
                                else:
                                    # request.get_host() includes the port.
                                    good_referer = request.get_host()

                                # Here we generate a list of all acceptable HTTP referers,
                                # including the current host since that has been validated
                                # upstream.
                                good_hosts = list(settings.CSRF_TRUSTED_ORIGINS)
                                good_hosts.append(good_referer)

                                if not any(is_same_domain(referer.netloc, host) for host in good_hosts):
                                    reason = REASON_BAD_REFERER % referer.geturl()
                                    return self._reject(request, reason)

                            csrf_token = request.META.get('CSRF_COOKIE')
                            if csrf_token is None:
                                # No CSRF cookie. For POST requests, we insist on a CSRF cookie,
                                # and in this way we can avoid all CSRF attacks, including login
                                # CSRF.
                                return self._reject(request, REASON_NO_CSRF_COOKIE)

                            # Check non-cookie token for match.
                            request_csrf_token = ""
                            if request.method == "POST":
                                try:
                                    request_csrf_token = request.POST.get('csrfmiddlewaretoken', '')
                                except IOError:
                                    # Handle a broken connection before we've completed reading
                                    # the POST data. process_view shouldn't raise any
                                    # exceptions, so we'll ignore and serve the user a 403
                                    # (assuming they're still listening, which they probably
                                    # aren't because of the error).
                                    pass

                            if request_csrf_token == "":
                                # Fall back to X-CSRFToken, to make things easier for AJAX,
                                # and possible for PUT/DELETE.
                                request_csrf_token = request.META.get(settings.CSRF_HEADER_NAME, '')

                            request_csrf_token = _sanitize_token(request_csrf_token)
                            if not _compare_salted_tokens(request_csrf_token, csrf_token):
                                return self._reject(request, REASON_BAD_TOKEN)

                        return self._accept(request)

                    def process_response(self, request, response):
                        if not getattr(request, 'csrf_cookie_needs_reset', False):
                            if getattr(response, 'csrf_cookie_set', False):
                                return response

                        if not request.META.get("CSRF_COOKIE_USED", False):
                            return response

                        # Set the CSRF cookie even if it's already set, so we renew
                        # the expiry timer.
                        self._set_token(request, response)
                        response.csrf_cookie_set = True
                        return response
                
                                
                class AuthenticationMiddleware(MiddlewareMixin):
                    def process_request(self, request):
                        assert hasattr(request, 'session'), (
                            "The Django authentication middleware requires session middleware "
                            "to be installed. Edit your MIDDLEWARE%s setting to insert "
                            "'django.contrib.sessions.middleware.SessionMiddleware' before "
                            "'django.contrib.auth.middleware.AuthenticationMiddleware'."
                        ) % ("_CLASSES" if settings.MIDDLEWARE is None else "")
                        request.user = SimpleLazyObject(lambda: get_user(request))
                

django中间件可以自定义有五种方法

掌握：

1.process_request()方法

规律:
请求来的时候，会从上往下依次执行每个中间件里面的process_request方法，如果没有就跳过。
但需要注意的是，如果在某个中间件的process_request方法中返回了一个HttpResponse对象的话，那么就不会在走下面的中间件了，会在同级别从下往上依次执行每个中间件的process_response方法

2.process_response()方法

响应走的时候，会从下至上依次执行每个中间件的process_response方法。
不过要注意的是，最后要返回一个response，这个形参就是返回给浏览器的数据，只要是参数有response的，最后都要返回一下，因为返回的response就是代表要返回给浏览器的数据，如果没有就是代表你想截获它

了解

3.process_view

这个方法是在路由匹配成功，进入视图层前执行的一个方法，但要注意的是如果我某一个中间件的process_view()方法里面返回了一个HttpResponse对象，则会掉头，从最底下，从下往上依次执行每个中间件的process_respnse方法

4.process_exception

这个方法要报错的时候才会执行，顺序从下往上

5.process_template_response()

是返回的对象含有render这个方法的时候执行，顺序是从下往上
def index(request):
       print('我是index视图函数')
        def render():
             return HttpResponse('什么鬼玩意')
        obj = HttpResponse('index')
        obj.render = render
        return obj

注意：如果要想让你写的中间件有效，那么写的类一定要继承自MiddlemareMixin

　　　　在seetings中注册自定义的中间件的时候，一定要注意路径不要写错

Csrf跨站请求伪造(钓鱼网站)

钓鱼网站

就是制作一个正儿八经的网站，欺骗用户转账

你比如中国银行转账，交易请求确确实实发送给了中国银行，也的确完成了交易，但是就是交易方不对。

内部原理：
就是在用户输入转账用户的那个input框做手脚

给这个input框不设置name属性，而是将这个设置下隐藏在下面的input框内，value值就是钓鱼网站受益人账号。

防止钓鱼网站的思路:

给每个返回给用户输入的form表单页面偷偷塞入一个特殊的随机字符串。

请求来的时候，会先比较是否与我保存的一致，不一致就不通过报个(403)

该随机字符串有以下特点:
　　1.同一个浏览器每一次访问都不一样

　　2.不同浏览器绝对不会重复

form表单来的时候就是固定一句话

{% csrf_token %}

ajax来的时候有3种避免csrf校验的

1.现在页面上写{% csrf_token %},利用标签查找  获取到该input键值信息
                {'username':'jason','csrfmiddlewaretoken':$('[name=csrfmiddlewaretoken]').val()}
                $('[name=csrfmiddlewaretoken]').val()
                
            2.直接书写'{{ csrf_token }}'
                {'username':'jason','csrfmiddlewaretoken':'{{ csrf_token }}'}
                {{ csrf_token }}
            
            3.你可以将该获取随机键值对的方法 写到一个js文件中,之后只需要导入该文件即可
                新建一个js文件 存放以下代码 之后导入即可 
                function getCookie(name) {
                    var cookieValue = null;
                    if (document.cookie && document.cookie !== '') {
                        var cookies = document.cookie.split(';');
                        for (var i = 0; i < cookies.length; i++) {
                            var cookie = jQuery.trim(cookies[i]);
                            // Does this cookie string begin with the name we want?
                            if (cookie.substring(0, name.length + 1) === (name + '=')) {
                                cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
                                break;
                            }
                        }
                    }
                    return cookieValue;
                }
                var csrftoken = getCookie('csrftoken');


                function csrfSafeMethod(method) {
                  // these HTTP methods do not require CSRF protection
                  return (/^(GET|HEAD|OPTIONS|TRACE)$/.test(method));
                }

                $.ajaxSetup({
                  beforeSend: function (xhr, settings) {
                    if (!csrfSafeMethod(settings.type) && !this.crossDomain) {
                      xhr.setRequestHeader("X-CSRFToken", csrftoken);
                    }
                  }
                });

接下来的2中需求

1.全部都要校验，但有几个不想让其校验

2.全部都不检验，但有几个想要其校验

        from django.utils.decorators import method_decorator    
            from django.views.decorators.csrf import csrf_exempt,csrf_protect
            # 这两个装饰器在给CBV装饰的时候 有一定的区别
            如果是csrf_protect 那么有三种方式
                # 第一种方式
                # @method_decorator(csrf_protect,name='post')  # 有效的
                class MyView(View):
                    # 第三种方式
                    # @method_decorator(csrf_protect)
                    def dispatch(self, request, *args, **kwargs):
                        res = super().dispatch(request, *args, **kwargs)
                        return res

                    def get(self,request):
                        return HttpResponse('get')
                    # 第二种方式
                    # @method_decorator(csrf_protect)  # 有效的
                    def post(self,request):
                        return HttpResponse('post')
                    
            如果是csrf_exempt 只有两种(只能给dispatch装)   特例
            @method_decorator(csrf_exempt,name='dispatch')  # 第二种可以不校验的方式
            class MyView(View):
                # @method_decorator(csrf_exempt)  # 第一种可以不校验的方式
                def dispatch(self, request, *args, **kwargs):
                    res = super().dispatch(request, *args, **kwargs)
                    return res

                def get(self,request):
                    return HttpResponse('get')

                def post(self,request):
                    return HttpResponse('post')
        
        总结 装饰器中只有csrf_exempt是特例,其他的装饰器在给CBV装饰的时候 都可以有三种方式

Auth用户登录认证模块

auth模块
            如果你想用auth模块   那么你就用全套
            
            
            
            跟用户相关的功能模块
                用户的注册 登陆 验证 修改密码 ...
            
            执行数据库迁移命令之后  会生成很多表  其中的auth_user是一张用户相关的表格
            添加数据
                createsuperuser  创建超级用户 这个超级用户就可以拥有登陆django admin后台管理的权限
        

        auth模块的功能
            查询用户
                from django.contrib import auth
                user_obj = auth.authenticate(username=username,password=password)  # 必须要用 因为数据库中的密码字段是密文的 而你获取的用户输入的是明文
            记录用户状态
                auth.login(request,user_obj)  # 将用户状态记录到session中
            判断用户是否登录
                print(request.user.is_authenticated)  # 判断用户是否登录  如果是你们用户会返回False
            用户登录之后 获取用户对象
                print(request.user)  # 如果没有执行auth.login那么拿到的是匿名用户
            校验用户是否登录
                from django.contrib.auth.decorators import  login_required
                @login_required(login_url='/xxx/')  # 局部配置
                def index(request):
                    pass
                
                # 全局配置  settings文件中
                LOGIN_URL = '/xxx/'
            验证密码是否正确
                request.user.check_password(old_password)
            修改密码    
                request.user.set_password(new_password)
                request.user.save()  # 修改密码的时候 一定要save保存 否则无法生效
            退出登陆
                auth.logout(request)  # request.session.flush()
            注册用户
                    # User.objects.create(username =username,password=password)  # 创建用户名的时候 千万不要再使用create 了
                    # User.objects.create_user(username =username,password=password)  # 创建普通用户
                    User.objects.create_superuser(username =username,password=password,email='123@qq.com')  # 创建超级用户  邮箱必填
        
        
        自定义auth_user表
            from django.contrib.auth.models import AbstractUser
            # Create your models here.
            # 第一种 使用一对一关系  不考虑



            # 第二种方式   使用类的继承
            class Userinfo(AbstractUser):
                # 千万不要跟原来表中的字段重复 只能创新
                phone = models.BigIntegerField()
                avatar = models.CharField(max_length=32)
            
            # 一定要在配置文件中 告诉django
            # 告诉django  orm不再使用auth默认的表  而是使用你自定义的表
            AUTH_USER_MODEL = 'app01.Userinfo'  # '应用名.类名'
        
        
        1.执行数据库迁移命令
            所有的auth模块功能 全部都基于你创建的表 
            而不再使用auth_user