1 files changed, 74 insertions, 0 deletions
diff --git a/src/zenhttp/servers/wsframecodec.h b/src/zenhttp/servers/wsframecodec.h
new file mode 100644
index 000000000..2d90b6fa1
--- /dev/null
+++ b/src/zenhttp/servers/wsframecodec.h
@@ -0,0 +1,74 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#pragma once
+
+#include <zenhttp/websocket.h>
+
+#include <cstddef>
+#include <cstdint>
+#include <optional>
+#include <span>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace zen {
+
+/**
+ * Result of attempting to parse a single WebSocket frame from a byte buffer
+ */
+struct WsFrameParseResult
+{
+	bool				 IsValid	   = false;	 // true if a complete frame was successfully parsed
+	size_t				 BytesConsumed = 0;		 // number of bytes consumed from the input buffer
+	WebSocketOpcode		 Opcode		   = WebSocketOpcode::kText;
+	bool				 Fin		   = false;
+	std::vector<uint8_t> Payload;
+};
+
+/**
+ * RFC 6455 WebSocket frame codec
+ *
+ * Provides static helpers for parsing client-to-server frames (which are
+ * always masked) and building server-to-client frames (which are never masked).
+ */
+struct WsFrameCodec
+{
+	/**
+	 * Try to parse one complete frame from the front of the buffer.
+	 *
+	 * Returns a result with IsValid == false and BytesConsumed == 0 when
+	 * there is not enough data yet.  The caller should accumulate more data
+	 * and retry.
+	 */
+	static WsFrameParseResult TryParseFrame(const uint8_t* Data, size_t Size);
+
+	/**
+	 * Build a server-to-client frame (no masking)
+	 */
+	static std::vector<uint8_t> BuildFrame(WebSocketOpcode Opcode, std::span<const uint8_t> Payload);
+
+	/**
+	 * Build a close frame with a status code and optional reason string
+	 */
+	static std::vector<uint8_t> BuildCloseFrame(uint16_t Code, std::string_view Reason = {});
+
+	/**
+	 * Build a client-to-server frame (with masking per RFC 6455)
+	 */
+	static std::vector<uint8_t> BuildMaskedFrame(WebSocketOpcode Opcode, std::span<const uint8_t> Payload);
+
+	/**
+	 * Build a masked close frame with status code and optional reason
+	 */
+	static std::vector<uint8_t> BuildMaskedCloseFrame(uint16_t Code, std::string_view Reason = {});
+
+	/**
+	 * Compute the Sec-WebSocket-Accept value per RFC 6455 section 4.2.2
+	 *
+	 * accept = Base64(SHA1(clientKey + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"))
+	 */
+	static std::string ComputeAcceptKey(std::string_view ClientKey);
+};
+
+}  // namespace zen