From ee12fa3e2f34cb0a5b0ccb2b7b444ec5fa158f8e Mon Sep 17 00:00:00 2001
From: Stefan Boberg <stefan@boberg.org>
Date: Fri, 27 Feb 2026 14:05:46 +0100
Subject: added Websocket client HttpWsClient

implemented in terms of asio
---
 src/zenhttp/servers/wsframecodec.cpp | 64 ++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

(limited to 'src/zenhttp/servers/wsframecodec.cpp')

diff --git a/src/zenhttp/servers/wsframecodec.cpp b/src/zenhttp/servers/wsframecodec.cpp
index 80045c576..a4c5e0f16 100644
--- a/src/zenhttp/servers/wsframecodec.cpp
+++ b/src/zenhttp/servers/wsframecodec.cpp
@@ -6,6 +6,7 @@
 #include <zencore/sha1.h>
 
 #include <cstring>
+#include <random>
 
 namespace zen {
 
@@ -135,6 +136,69 @@ WsFrameCodec::BuildCloseFrame(uint16_t Code, std::string_view Reason)
 	return BuildFrame(WebSocketOpcode::kClose, Payload);
 }
 
+//////////////////////////////////////////////////////////////////////////
+//
+// Frame building (client-to-server, with masking)
+//
+
+std::vector<uint8_t>
+WsFrameCodec::BuildMaskedFrame(WebSocketOpcode Opcode, std::span<const uint8_t> Payload)
+{
+	std::vector<uint8_t> Frame;
+
+	const size_t PayloadLen = Payload.size();
+
+	// FIN + opcode
+	Frame.push_back(0x80 | static_cast<uint8_t>(Opcode));
+
+	// Payload length with mask bit set
+	if (PayloadLen < 126)
+	{
+		Frame.push_back(0x80 | static_cast<uint8_t>(PayloadLen));
+	}
+	else if (PayloadLen <= 0xFFFF)
+	{
+		Frame.push_back(0x80 | 126);
+		Frame.push_back(static_cast<uint8_t>((PayloadLen >> 8) & 0xFF));
+		Frame.push_back(static_cast<uint8_t>(PayloadLen & 0xFF));
+	}
+	else
+	{
+		Frame.push_back(0x80 | 127);
+		for (int i = 7; i >= 0; --i)
+		{
+			Frame.push_back(static_cast<uint8_t>((PayloadLen >> (i * 8)) & 0xFF));
+		}
+	}
+
+	// Generate random 4-byte mask key
+	static thread_local std::mt19937 s_Rng(std::random_device{}());
+	uint32_t						 MaskValue = s_Rng();
+	uint8_t							 MaskKey[4];
+	std::memcpy(MaskKey, &MaskValue, 4);
+
+	Frame.insert(Frame.end(), MaskKey, MaskKey + 4);
+
+	// Masked payload
+	for (size_t i = 0; i < PayloadLen; ++i)
+	{
+		Frame.push_back(Payload[i] ^ MaskKey[i & 3]);
+	}
+
+	return Frame;
+}
+
+std::vector<uint8_t>
+WsFrameCodec::BuildMaskedCloseFrame(uint16_t Code, std::string_view Reason)
+{
+	std::vector<uint8_t> Payload;
+	Payload.push_back(static_cast<uint8_t>((Code >> 8) & 0xFF));
+	Payload.push_back(static_cast<uint8_t>(Code & 0xFF));
+	Payload.insert(Payload.end(), Reason.begin(), Reason.end());
+
+	return BuildMaskedFrame(WebSocketOpcode::kClose, Payload);
+}
+
 //////////////////////////////////////////////////////////////////////////
 //
 // Sec-WebSocket-Accept key computation (RFC 6455 section 4.2.2)
-- 
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