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