vweb: adding a vweb.csrf protection module (#15586)

vlib/vweb/csrf/csrf_test.v

@@ -0,0 +1,30 @@
+import time
+import net.http
+import vweb
+import vweb.csrf
+
+const sport = 10801
+
+struct App {
+	csrf.App
+}
+
+// index - will handle requests to path '/'
+fn (mut app App) index() vweb.Result {
+	// Set a Csrf-Cookie(Token will be generated automatically) and set http_only-status. If no argument ist passed, it will be true by default.
+	app.set_csrf_cookie(csrf.HttpOnly{false})
+	// Get the token-value from the csrf-cookie that was just setted
+	token := app.get_csrf_token() or { panic(err) }
+	return app.text("Csrf-Token set! It's value is: $token")
+}
+
+fn test_send_a_request_to_homepage_expecting_a_csrf_cookie() ? {
+	go vweb.run_at(&App{}, vweb.RunParams{ port: sport })
+	time.sleep(500 * time.millisecond)
+	res := http.get('http://localhost:$sport/')?
+	if res.header.str().contains('__Host-Csrf-Token') {
+		assert true
+	} else {
+		assert false
+	}
+}