Disable legacy media request fallbacks by default.

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/config/mod.rs

@@ -1318,6 +1318,12 @@ pub struct Config {
 	#[serde(default)]
 	pub allow_legacy_media: bool,
 
+	/// Fallback to requesting legacy unauthenticated media from remote servers.
+	/// Unauthenticated media was removed in ~2024Q3; enabling this adds
+	/// considerable federation requests which are unlikely to succeed.
+	#[serde(default)]
+	pub request_legacy_media: bool,
+
 	#[serde(default = "true_fn")]
 	pub freeze_legacy_media: bool,
 

src/service/media/remote.rs

@@ -35,7 +35,9 @@ pub async fn fetch_remote_thumbnail(
 		.fetch_thumbnail_authenticated(mxc, user, server, timeout_ms, dim)
 		.await;
 
-	if let Err(Error::Request(NotFound, ..)) = &result {
+	if let Err(Error::Request(NotFound, ..)) = &result
+		&& self.services.server.config.request_legacy_media
+	{
 		return self
 			.fetch_thumbnail_unauthenticated(mxc, user, server, timeout_ms, dim)
 			.await;
@@ -58,7 +60,9 @@ pub async fn fetch_remote_content(
 		.fetch_content_authenticated(mxc, user, server, timeout_ms)
 		.await;
 
-	if let Err(Error::Request(NotFound, ..)) = &result {
+	if let Err(Error::Request(NotFound, ..)) = &result
+		&& self.services.server.config.request_legacy_media
+	{
 		return self
 			.fetch_content_unauthenticated(mxc, user, server, timeout_ms)
 			.await;

tuwunel-example.toml

@@ -1130,6 +1130,12 @@
 #
 #allow_legacy_media = false
 
+# Fallback to requesting legacy unauthenticated media from remote servers.
+# Unauthenticated media was removed in ~2024Q3; enabling this adds
+# considerable federation requests which are unlikely to succeed.
+#
+#request_legacy_media = false
+
 # This item is undocumented. Please contribute documentation for it.
 #
 #freeze_legacy_media = true