django中的csrf

CSRF是Cross Site Request Forgery的缩写，称其为“跨站请求伪造”。常与XSS想提并论，但它与XSS非常不同，并且攻击方式几乎相左。XSS利用站点内的信任用户，而CSRF则通过伪装来自受信任用户的请求来利用受信任的网站。与XSS攻击相比，CSRF攻击往往不大流行（因此对其进行防范的资源也相当稀少）和难以防范，所以有时候被认为比XSS更具危险性。

使用django出现以下错误时就是因为csrf没有校验通过

CSRF verification failed. Request aborted. Then you need to add  ‘django.middleware.csrf.CsrfViewMiddleware’, and  ‘django.middleware.csrf.CsrfResponseMiddleware’ your settings.py file.

解决方法是将setting.py的MIDDLEWARE_CLASSES中修改CsrfResponseMiddleware and CsrfMiddleware为CsrfViewMiddleware，并且在模版中CSRF标签，即在form区域内加上了{% csrf_token %}。

但是加上之后通过ajax的post方式提交表单时依然会出现错误，原因还是csrf没有通过，解决方法是在需要ajax提交数据的页面加入以下javascropt代码：

$(document).ajaxSend(function(event, xhr, settings) {    function getCookie(name) {        var cookieValue = null;        if (document.cookie && document.cookie != '') {            var cookies = document.cookie.split(';');            for (var i = 0; i < cookies.length; i++) {                var cookie = jQuery.trim(cookies[i]);                // Does this cookie string begin with the name we want?                if (cookie.substring(0, name.length + 1) == (name + '=')) {                    cookieValue = decodeURIComponent(cookie.substring(name.length + 1));                    break;                }            }        }        return cookieValue;    }    function sameOrigin(url) {        // url could be relative or scheme relative or absolute        var host = document.location.host; // host + port        var protocol = document.location.protocol;        var sr_origin = '//' + host;        var origin = protocol + sr_origin;        // Allow absolute or scheme relative URLs to same origin        return (url == origin || url.slice(0, origin.length + 1) == origin + '/') ||            (url == sr_origin || url.slice(0, sr_origin.length + 1) == sr_origin + '/') ||            // or any other URL that isn't scheme relative or absolute i.e relative.            !(/^(\/\/|http:|https:).*/.test(url));    }    function safeMethod(method) {        return (/^(GET|HEAD|OPTIONS|TRACE)$/.test(method));    }    if (!safeMethod(settings.type) && sameOrigin(settings.url)) {        xhr.setRequestHeader("X-CSRFToken", getCookie('csrftoken'));    }});

参考：https://docs.djangoproject.com/en/dev/ref/contrib/csrf/#ajax