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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,79 @@ | ||
| <!doctype html> | ||
| <html lang="en"> | ||
| <head> | ||
| <meta charset="UTF-8" /> | ||
| <meta name="viewport" content="width=device-width, initial-scale=1.0" /> | ||
| <title>AJAX Request with CSRF Token</title> | ||
| </head> | ||
| <body> | ||
| <div id="ajaxResponse"></div> | ||
| <script> | ||
| document.addEventListener('DOMContentLoaded', () => { | ||
| createCSRFTokenContainer(); | ||
| document | ||
| .getElementById('makeRequestButton') | ||
| .addEventListener('click', () => { | ||
| // Make an AJAX request when the button is clicked, it should | ||
| // show a successful message when no attack is made | ||
| var xhr = new XMLHttpRequest(); | ||
|
|
||
| var csrfToken = getCSRFTokenFromClient(); | ||
|
|
||
| xhr.open('POST', '/protected', true); | ||
|
|
||
| xhr.setRequestHeader('CSRF-Token', csrfToken); | ||
|
|
||
| xhr.onreadystatechange = () => { | ||
| if (xhr.readyState === XMLHttpRequest.DONE) { | ||
| // The server validates if the token sent in the header, if it matches the one | ||
| // stored on the server, it sends an OK status code. | ||
| // else it blocks the request | ||
| if (xhr.status === 200) { | ||
| document.getElementById('ajaxResponse').innerText = | ||
| "You're allowed, come in"; | ||
| } else { | ||
| // Possible forgery | ||
| document.getElementById('ajaxResponse').innerText = | ||
| "You're blocked, the CSRF Token has been tampered with"; | ||
| console.error('AJAX request failed:', xhr.status); | ||
| } | ||
| } | ||
| }; | ||
| }); | ||
| }); | ||
|
|
||
| function getCSRFTokenFromServer() { | ||
| // When the user authenticated, the user ID was set as cookie (HttpOnly, Secure, Lax and all that), sent with every request | ||
| // the server will generate a secure random anti-CSRF token and associate it with that user ID on its end | ||
| // send a POST to the server you'll get the token. | ||
| return 'CSRF_TOKEN'; | ||
| } | ||
|
|
||
| function createCSRFTokenContainer() { | ||
| var csrfToken = getCSRFTokenFromServer(); // New div element to hold the hidden token | ||
| var csrfDiv = document.createElement('div'); | ||
| csrfDiv.id = 'csrfTokenDiv'; // Create a hidden input field and set its value to the generated CSRF token | ||
| var input = document.createElement('input'); | ||
| input.type = 'hidden'; | ||
| input.name = 'CSRFToken'; | ||
| input.value = csrfToken; | ||
| csrfDiv.appendChild(input); | ||
| } | ||
|
|
||
| function getCSRFTokenFromClient() { | ||
| var csrfTokenDiv = document.getElementById('csrfTokenDiv'); | ||
|
|
||
| if (csrfTokenDiv) { | ||
| var inputField = csrfTokenDiv.querySelector( | ||
| 'input[type="hidden"][name="CSRFToken"]' | ||
| ); | ||
|
|
||
| if (inputField) { | ||
| return inputField.value; // The CSRF token value | ||
| } | ||
| } | ||
| } | ||
| </script> | ||
| <button id="makeRequestButton">Make AJAX Request</button> | ||
| </body> | ||
| </html> |