1 files changed, 55 insertions, 8 deletions

diff --git a/src/zenhttp/servers/wsframecodec.cpp b/src/zenhttp/servers/wsframecodec.cpp
index e452141fe..781f04c5e 100644
--- a/src/zenhttp/servers/wsframecodec.cpp
+++ b/src/zenhttp/servers/wsframecodec.cpp
@@ -16,7 +16,7 @@ namespace zen {
 //
 
 WsFrameParseResult
-WsFrameCodec::TryParseFrame(const uint8_t* Data, size_t Size)
+WsFrameCodec::TryParseFrame(const uint8_t* Data, size_t Size, bool RequireMask)
 {
 	// Minimum frame: 2 bytes header (unmasked server frames) or 6 bytes (masked client frames)
 	if (Size < 2)
@@ -24,10 +24,48 @@ WsFrameCodec::TryParseFrame(const uint8_t* Data, size_t Size)
 		return {};
 	}
 
-	const bool	  Fin		 = (Data[0] & 0x80) != 0;
-	const uint8_t OpcodeRaw	 = Data[0] & 0x0F;
-	const bool	  Masked	 = (Data[1] & 0x80) != 0;
-	uint64_t	  PayloadLen = Data[1] & 0x7F;
+	const bool	  Fin		  = (Data[0] & 0x80) != 0;
+	const uint8_t RsvBits	  = Data[0] & 0x70;
+	const uint8_t OpcodeRaw	  = Data[0] & 0x0F;
+	const bool	  Masked	  = (Data[1] & 0x80) != 0;
+	const uint8_t ShortLength = Data[1] & 0x7F;
+	uint64_t	  PayloadLen  = ShortLength;
+
+	const bool IsControlFrame = (OpcodeRaw & 0x08) != 0;
+
+	// RFC 6455 section 5.2: RSV1/2/3 must be zero unless a negotiated extension
+	// defines them.  We do not negotiate any extensions, so any non-zero RSV bit
+	// is a protocol violation.
+	if (RsvBits != 0)
+	{
+		WsFrameParseResult Error;
+		Error.Status = WsFrameParseStatus::kProtocolError;
+		return Error;
+	}
+
+	// RFC 6455 section 5.5: control frames (Close / Ping / Pong and any opcode
+	// in 0x8..0xF) MUST NOT be fragmented and MUST have a payload of 125 bytes
+	// or less.  Rejecting fragmented or oversized control frames prevents a
+	// peer from tying up unbounded memory inside an auto-pong, and closes off
+	// a class of smuggling tricks where handlers might observe partial control
+	// payloads.
+	if (IsControlFrame && (!Fin || ShortLength > 125))
+	{
+		WsFrameParseResult Error;
+		Error.Status = WsFrameParseStatus::kProtocolError;
+		return Error;
+	}
+
+	// RFC 6455 section 5.1: a server MUST close the connection upon receiving an
+	// unmasked client frame.  Signal this distinctly from "need more data" so the
+	// server close path can trigger a 1002 close rather than stalling for bytes
+	// that will never satisfy the parse.
+	if (RequireMask && !Masked)
+	{
+		WsFrameParseResult Error;
+		Error.Status = WsFrameParseStatus::kProtocolError;
+		return Error;
+	}
 
 	size_t HeaderSize = 2;
 
@@ -51,11 +89,19 @@ WsFrameCodec::TryParseFrame(const uint8_t* Data, size_t Size)
 		HeaderSize = 10;
 	}
 
-	// Reject frames with unreasonable payload sizes to prevent OOM
-	static constexpr uint64_t kMaxPayloadSize = 256 * 1024 * 1024;	// 256 MB
+	// Reject frames with unreasonable payload sizes to bound per-connection
+	// memory.  Parsers accumulate the whole frame before dispatch (see the
+	// read loops in wsasio.cpp / wshttpsys.cpp), so this cap also bounds the
+	// accumulator: a peer that advertises a large frame and streams bytes
+	// slowly cannot grow buffers past this limit.  4 MB is well above anything
+	// the monitoring / stats endpoints produce; raise it if a legitimate use
+	// case emerges.
+	static constexpr uint64_t kMaxPayloadSize = 4 * 1024 * 1024;  // 4 MB
 	if (PayloadLen > kMaxPayloadSize)
 	{
-		return {};
+		WsFrameParseResult Error;
+		Error.Status = WsFrameParseStatus::kProtocolError;
+		return Error;
 	}
 
 	const size_t MaskSize	= Masked ? 4 : 0;
@@ -70,6 +116,7 @@ WsFrameCodec::TryParseFrame(const uint8_t* Data, size_t Size)
 	const uint8_t* PayloadData = Data + HeaderSize + MaskSize;
 
 	WsFrameParseResult Result;
+	Result.Status		 = WsFrameParseStatus::kValid;
 	Result.IsValid		 = true;
 	Result.BytesConsumed = TotalFrame;
 	Result.Opcode		 = static_cast<WebSocketOpcode>(OpcodeRaw);