feat: Allow configuring the desired client IP source

changelog.d/1932.feature

@@ -0,0 +1 @@
+Added a configuration option to allow choosing a client IP source that is not the TCP connecting IP. Contributed by @nex.

conduwuit-example.toml

@@ -290,6 +290,26 @@
 #
 #ip_lookup_strategy = 5
 
+# The source to use for discovering the real connecting client IP.
+#
+# Takes the number of any of the following options:
+#
+# 0 - Use the IP address of the TCP connection
+# 1 - `Cf-Connecting-Ip` header
+# 2 - `CloudFront-Viewer-Address` header
+# 3 - `Fly-Client-IP` header
+# 4 - rightmost value of the `X-Forwarded-For` header
+# 5 - `True-Client-Ip` header
+# 6 - `X-Envoy-External-Address` header
+# 7 - `X-Real-Ip` header
+#
+# Only change this from `0` if you are certain only your reverse proxy
+# will send the expected header. There is no "is the connecting IP allowed
+# to set this header" check; if the header selected is present, it is
+# used.
+#
+#request_ip_source = 0
+
 # Max request size for file uploads in bytes. Defaults to 20MB.
 # Also limits incoming federated media.
 #

src/core/config/mod.rs

@@ -370,6 +370,28 @@ pub struct Config {
 	#[serde(default = "default_ip_lookup_strategy")]
 	pub ip_lookup_strategy: u8,
 
+	/// The source to use for discovering the real connecting client IP.
+	///
+	/// Takes the number of any of the following options:
+	///
+	/// 0 - Use the IP address of the TCP connection
+	/// 1 - `Cf-Connecting-Ip` header
+	/// 2 - `CloudFront-Viewer-Address` header
+	/// 3 - `Fly-Client-IP` header
+	/// 4 - rightmost value of the `X-Forwarded-For` header
+	/// 5 - `True-Client-Ip` header
+	/// 6 - `X-Envoy-External-Address` header
+	/// 7 - `X-Real-Ip` header
+	///
+	/// Only change this from `0` if you are certain only your reverse proxy
+	/// will send the expected header. There is no "is the connecting IP allowed
+	/// to set this header" check; if the header selected is present, it is
+	/// used.
+	///
+	/// default: 0
+	#[serde(default)]
+	pub request_ip_source: u8,
+
 	/// Max request size for file uploads in bytes. Defaults to 20MB.
 	/// Also limits incoming federated media.
 	///

src/router/layers.rs

@@ -48,6 +48,17 @@ pub(crate) fn build(services: &Arc<Services>) -> Result<(Router, Guard)> {
 	))]
 	let layers = layers.layer(compression_layer(server));
 
+	let client_ip_layer = match services.config.request_ip_source {
+		| 1 => ClientIpSource::CfConnectingIp,
+		| 2 => ClientIpSource::CloudFrontViewerAddress,
+		| 3 => ClientIpSource::FlyClientIp,
+		| 4 => ClientIpSource::RightmostXForwardedFor,
+		| 5 => ClientIpSource::TrueClientIp,
+		| 6 => ClientIpSource::XEnvoyExternalAddress,
+		| 7 => ClientIpSource::XRealIp,
+		| _ => ClientIpSource::ConnectInfo,
+	};
+
 	let services_ = services.clone();
 	let layers = layers
 		.layer(SetSensitiveHeadersLayer::new([header::AUTHORIZATION]))
@@ -59,7 +70,7 @@ pub(crate) fn build(services: &Arc<Services>) -> Result<(Router, Guard)> {
 				.on_response(DefaultOnResponse::new().level(Level::DEBUG)),
 		)
 		.layer(axum::middleware::from_fn_with_state(Arc::clone(services), request::handle))
-		.layer(ClientIpSource::ConnectInfo.into_extension())
+		.layer(client_ip_layer.into_extension())
 		.layer(ResponseBodyTimeoutLayer::new(Duration::from_secs(
 			server.config.client_response_timeout,
 		)))