api: fix CSRF error when using POST/PATCH/PUT in API Browser

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

authentik/api/templates/api/swagger.html

@@ -11,6 +11,29 @@ authentik API Browser
 {% endblock %}
 
 {% block body %}
+<script>
+function getCookie(name) {
+    let cookieValue = "";
+    if (document.cookie && document.cookie !== "") {
+        const cookies = document.cookie.split(";");
+        for (let i = 0; i < cookies.length; i++) {
+            const cookie = cookies[i].trim();
+            // 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;
+}
+window.addEventListener('DOMContentLoaded', (event) => {
+    const rapidocEl = document.querySelector('rapi-doc');
+    rapidocEl.addEventListener('before-try', (e) => {
+        e.detail.request.headers.append('X-CSRFToken', getCookie("authentik_csrf"));
+    });
+});
+</script>
 <rapi-doc
     spec-url="{{ path }}"
     heading-text="authentik"