From c0131fe452f3442a16d5aafe80fbfda377f8f41c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Ludwig?= <sludwig@rejectedsoftware.com>
Date: Mon, 26 Jun 2017 22:49:35 +0200
Subject: [PATCH] Assemble frames in OutgoingWebSocketMessage in a single
 buffer. Fixes #1791.

---
 http/vibe/http/websockets.d | 110 +++++++++++++++++++++---------------
 1 file changed, 66 insertions(+), 44 deletions(-)

diff --git a/http/vibe/http/websockets.d b/http/vibe/http/websockets.d
index 0e69fa16d8..6e81ade792 100644
--- a/http/vibe/http/websockets.d
+++ b/http/vibe/http/websockets.d
@@ -648,7 +648,6 @@ final class WebSocket {
 */
 final class OutgoingWebSocketMessage : OutputStream {
 @safe:
-
 	private {
         RandomNumberStream m_rng;
 		Stream m_conn;
@@ -657,7 +656,7 @@ final class OutgoingWebSocketMessage : OutputStream {
 		bool m_finalized = false;
 	}
 
-	this( Stream conn, FrameOpcode frameOpcode, RandomNumberStream rng )
+	this(Stream conn, FrameOpcode frameOpcode, RandomNumberStream rng)
 	{
 		assert(conn !is null);
 		m_conn = conn;
@@ -668,6 +667,12 @@ final class OutgoingWebSocketMessage : OutputStream {
 	size_t write(in ubyte[] bytes, IOMode mode)
 	{
 		assert(!m_finalized);
+
+		if (!m_buffer.data.length) {
+			ubyte[Frame.maxHeaderSize] header_padding;
+			m_buffer.put(header_padding[]);
+		}
+
 		m_buffer.put(bytes);
 		return bytes.length;
 	}
@@ -675,27 +680,34 @@ final class OutgoingWebSocketMessage : OutputStream {
 	void flush()
 	{
 		assert(!m_finalized);
-		Frame frame;
-		frame.opcode = m_frameOpcode;
-		frame.fin = false;
-		frame.payload = m_buffer.data;
-		frame.writeFrame(m_conn, m_rng);
-		m_buffer.clear();
-		m_conn.flush();
+		if (m_buffer.data.length > 0)
+			sendFrame(false);
 	}
 
 	void finalize()
 	{
 		if (m_finalized) return;
 		m_finalized = true;
+		sendFrame(true);
+	}
+
+	private void sendFrame(bool fin)
+	{
+		if (!m_buffer.data.length)
+			write(null, IOMode.once);
+
+		assert(m_buffer.data.length >= Frame.maxHeaderSize);
 
 		Frame frame;
-		frame.fin = true;
+		frame.fin = fin;
 		frame.opcode = m_frameOpcode;
-		frame.payload = m_buffer.data;
-		frame.writeFrame(m_conn, m_rng);
-		m_buffer.clear();
+		frame.payload = m_buffer.data[Frame.maxHeaderSize .. $];
+		auto hsize = frame.getHeaderSize(m_rng !is null);
+		auto msg = m_buffer.data[Frame.maxHeaderSize-hsize .. $];
+		frame.writeHeader(msg[0 .. hsize], m_rng);
+		m_conn.write(msg);
 		m_conn.flush();
+		m_buffer.clear();
 	}
 
 	alias write = OutputStream.write;
@@ -707,7 +719,6 @@ final class OutgoingWebSocketMessage : OutputStream {
 */
 final class IncomingWebSocketMessage : InputStream {
 @safe:
-
 	private {
         RandomNumberStream m_rng;
 		Stream m_conn;
@@ -797,7 +808,7 @@ private immutable s_webSocketGuid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
  * Currently only 6 values are defined, however the opcode is defined as
  * taking 4 bytes.
  */
-enum FrameOpcode : uint {
+private enum FrameOpcode : uint {
 	continuation = 0x0,
 	text = 0x1,
 	binary = 0x2,
@@ -807,51 +818,62 @@ enum FrameOpcode : uint {
 }
 
 
-struct Frame {
+private struct Frame {
 @safe:
+	enum maxHeaderSize = 14;
 
 	bool fin;
 	FrameOpcode opcode;
 	ubyte[] payload;
 
-	void writeFrame(OutputStream stream, RandomNumberStream sys_rng)
+	size_t getHeaderSize(bool mask)
 	{
-		import vibe.stream.wrapper;
-
-		auto rng = StreamOutputRange(stream);
+		size_t ret = 1;
+		if (payload.length < 126) ret += 1;
+		else if (payload.length <= 65536) ret += 3;
+		else ret += 9;
+		if (mask) ret += 4;
+		return ret;
+	}
 
+	void writeHeader(ubyte[] dst, RandomNumberStream sys_rng)
+	{
         ubyte[4] buff;
 		ubyte firstByte = cast(ubyte)opcode;
 		if (fin) firstByte |= 0x80;
-		rng.put(firstByte);
-
-		auto b1 = 0;
-		if (sys_rng) {
-			b1 = 0x80;
-		}
-
-		if( payload.length < 126 ) {
-			rng.put(std.bitmanip.nativeToBigEndian(cast(ubyte)(b1 | payload.length)));
-		} else if( payload.length <= 65536 ) {
-            buff[0] = cast(ubyte) (b1 | 126);
-			rng.put(buff[0 .. 1]);
-			rng.put(std.bitmanip.nativeToBigEndian(cast(ushort)payload.length));
+		dst[0] = firstByte;
+		dst = dst[1 .. $];
+
+		auto b1 = sys_rng ? 0x80 : 0x00;
+
+		if (payload.length < 126) {
+			dst[0] = cast(ubyte)(b1 | payload.length);
+			dst = dst[1 .. $];
+		} else if (payload.length <= 65536) {
+			dst[0] = cast(ubyte) (b1 | 126);
+			dst[1 .. 3] = std.bitmanip.nativeToBigEndian(cast(ushort)payload.length);
+			dst = dst[3 .. $];
 		} else {
-            buff[0] = cast(ubyte) (b1 | 127);
-			rng.put(buff[0 .. 1]);
-			rng.put(std.bitmanip.nativeToBigEndian(payload.length));
+			dst[0] = cast(ubyte) (b1 | 127);
+			dst[1 .. 9] = std.bitmanip.nativeToBigEndian(cast(ulong)payload.length);
+			dst = dst[9 .. $];
 		}
 
 		if (sys_rng) {
-            sys_rng.read(buff);
-			rng.put(buff);
-			for (size_t i = 0; i < payload.length; i++) {
-				payload[i] ^= buff[i % 4];
-			}
-			rng.put(payload);
-		}else {
-			rng.put(payload);
+            sys_rng.read(dst[0 .. 4]);
+			for (size_t i = 0; i < payload.length; i++)
+				payload[i] ^= dst[i % 4];
 		}
+	}
+
+	void writeFrame(OutputStream stream, RandomNumberStream sys_rng)
+	{
+		import vibe.stream.wrapper;
+
+		auto rng = StreamOutputRange(stream);
+		ubyte[maxHeaderSize] hdr;
+		writeHeader(hdr[], sys_rng);
+		rng.put(hdr[0 .. getHeaderSize(sys_rng !is null)]);
 		rng.flush();
 		stream.flush();
 	}