fix: fallback to Host header when the custom HOST_HEADER is not in the request (#11154)

Co-authored-by: Bob Fanger <[email protected]>
Co-authored-by: Ben McCann <[email protected]>
Co-authored-by: Rich Harris <[email protected]>

Author: 4 people

.changeset/spotty-yaks-lie.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-node': patch
+---
+
+fix: fallback to `host` header if header specified by `HOST_HEADER` is not in request headers

packages/adapter-node/src/handler.js

@@ -19,7 +19,7 @@ const origin = env('ORIGIN', undefined);
 const xff_depth = parseInt(env('XFF_DEPTH', '1'));
 const address_header = env('ADDRESS_HEADER', '').toLowerCase();
 const protocol_header = env('PROTOCOL_HEADER', '').toLowerCase();
-const host_header = env('HOST_HEADER', 'host').toLowerCase();
+const host_header = env('HOST_HEADER', '').toLowerCase();
 const port_header = env('PORT_HEADER', '').toLowerCase();
 
 const body_size_limit = parse_as_bytes(env('BODY_SIZE_LIMIT', '512K'));
@@ -182,14 +182,11 @@ function sequence(handlers) {
  * @returns
  */
 function get_origin(headers) {
-	const protocol = (protocol_header && headers[protocol_header]) || 'https';
-	const host = headers[host_header];
+	const protocol = (protocol_header && headers[protocol_header]) ?? 'https';
+	const host = (host_header && headers[host_header]) ?? headers['host'];
 	const port = port_header && headers[port_header];
-	if (port) {
-		return `${protocol}://${host}:${port}`;
-	} else {
-		return `${protocol}://${host}`;
-	}
+
+	return port ? `${protocol}://${host}:${port}` : `${protocol}://${host}`;
 }
 
 export const handler = sequence(