Allow streaming with body_size_limit (#6702)

* Allow streaming with body_size_limit

* More detailed error message

* fix formatting

* Clarify error message

* Update packages/kit/src/exports/node/index.js

* Create fair-rivers-repair.md

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

Author: 3 people

.changeset/fair-rivers-repair.md

@@ -0,0 +1,5 @@
+---
+"@sveltejs/adapter-node": patch
+---
+
+Allow streaming when `BODY_SIZE_LIMIT` is set

packages/adapter-node/README.md

@@ -71,7 +71,7 @@ Instead, we read from the _right_, accounting for the number of trusted proxies.
 
 ### `BODY_SIZE_LIMIT`
 
-The maximum request body size to accept in bytes. Defaults to 512kb. This option does not allow streaming. You can disable this option with a value of 0 and implement a custom check in [`handle`](https://kit.svelte.dev/docs/hooks#server-hooks-handle) if you need something more advanced.
+The maximum request body size to accept in bytes including while streaming. Defaults to 512kb. You can disable this option with a value of 0 and implement a custom check in [`handle`](https://kit.svelte.dev/docs/hooks#server-hooks-handle) if you need something more advanced.
 
 ## Options
 

packages/kit/src/exports/node/index.js

@@ -11,23 +11,22 @@ function get_raw_body(req, body_size_limit) {
 		return null;
 	}
 
-	const length = Number(h['content-length']);
+	const content_length = Number(h['content-length']);
 
 	// check if no request body
 	if (
-		(req.httpVersionMajor === 1 && isNaN(length) && h['transfer-encoding'] == null) ||
-		length === 0
+		(req.httpVersionMajor === 1 && isNaN(content_length) && h['transfer-encoding'] == null) ||
+		content_length === 0
 	) {
 		return null;
 	}
 
+	let length = content_length;
+
 	if (body_size_limit) {
 		if (!length) {
-			throw new Error(
-				`Received content-length of ${length}. content-length must be provided when body size limit is specified.`
-			);
-		}
-		if (length > body_size_limit) {
+			length = body_size_limit;
+		} else if (length > body_size_limit) {
 			throw new Error(
 				`Received content-length of ${length}, but only accept up to ${body_size_limit} bytes.`
 			);
@@ -59,7 +58,13 @@ function get_raw_body(req, body_size_limit) {
 
 				size += chunk.length;
 				if (size > length) {
-					controller.error(new Error('content-length exceeded'));
+					req.destroy(
+						new Error(
+							`request body size exceeded ${
+								content_length ? "'content-length'" : 'BODY_SIZE_LIMIT'
+							} of ${length}`
+						)
+					);
 					return;
 				}