Use proper header delimiter

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.1.1
+
+- Use proper headers delimiter.
+
 ## 2.1.0
 
 - Support Firefox.

lib/server/sse_handler.dart

@@ -11,12 +11,14 @@ import 'package:pedantic/pedantic.dart';
 import 'package:shelf/shelf.dart' as shelf;
 import 'package:stream_channel/stream_channel.dart';
 
+// RFC 2616 requires carriage return delimiters.
 String _sseHeaders(String origin) => 'HTTP/1.1 200 OK\r\n'
-    'Content-Type: text/event-stream\n\n'
-    'Cache-Control: no-cache\n\n'
-    'Connection: keep-alive\n\n'
-    'Access-Control-Allow-Credentials: true\n\n'
-    'Access-Control-Allow-Origin: $origin\n\n'
+    'Content-Type: text/event-stream\r\n'
+    'Cache-Control: no-cache\r\n'
+    'Connection: keep-alive\r\n'
+    'Access-Control-Allow-Credentials: true\r\n'
+    'Access-Control-Allow-Origin: $origin\r\n'
+    // Firefox requires double new line.
     '\n\n';
 
 /// A bi-directional SSE connection between server and browser.

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sse
-version: 2.1.0
+version: 2.1.1
 author: Dart Team <[email protected]>
 homepage: https://github.com/dart-lang/sse
 description: >-