fix: payload parsing for 64 byte payloads (#32)

PR by [baris-btcturk](chronoxor/NetCoreServer#329)

Author: stratdev3

release.md

@@ -21,6 +21,10 @@ Notes :
 ## v13.1.0 / _(2025-04-??)_
 Maintenance
 
+### fix
+
+- fix payload parsing for 64 byte payloads (#32), PR by [baris-btcturk](https://github.com/chronoxor/NetCoreServer/pull/329)
+
 ### feature
 
 - made possible to append extra response http headers in PerformServerUpgrade stage (#31), PR by [lifeengines](https://github.com/chronoxor/NetCoreServer/pull/297) to fix [bramley-jetcharge

src/SimpleW/NetCoreServer/WebSocket.cs

@@ -410,7 +410,16 @@ public void PrepareReceiveFrame(byte[] buffer, long offset, long size)
                             }
                         }
 
-                        payload = ((WsReceiveFrameBuffer[2] << 56) | (WsReceiveFrameBuffer[3] << 48) | (WsReceiveFrameBuffer[4] << 40) | (WsReceiveFrameBuffer[5] << 32) | (WsReceiveFrameBuffer[6] << 24) | (WsReceiveFrameBuffer[7] << 16) | (WsReceiveFrameBuffer[8] << 8) | (WsReceiveFrameBuffer[9] << 0));
+                        // payload, force convert to long with 0xFFL
+                        payload = ((WsReceiveFrameBuffer[2] & 0xFFL) << 56) |
+                                  ((WsReceiveFrameBuffer[3] & 0xFFL) << 48) |
+                                  ((WsReceiveFrameBuffer[4] & 0xFFL) << 40) |
+                                  ((WsReceiveFrameBuffer[5] & 0xFFL) << 32) |
+                                  ((WsReceiveFrameBuffer[6] & 0xFFL) << 24) |
+                                  ((WsReceiveFrameBuffer[7] & 0xFFL) << 16) |
+                                  ((WsReceiveFrameBuffer[8] & 0xFFL) << 8)  |
+                                  ((WsReceiveFrameBuffer[9] & 0xFFL));
+
                         WsHeaderSize = 10 + (mask ? 4 : 0);
                         WsPayloadSize = payload;
                     }