From 054d252e1e6cd3b70f9b25cb8f32eeea0b519f81 Mon Sep 17 00:00:00 2001
From: "build-mesh.bot" <build-mesh.bot@stormshield.eu>
Date: Thu, 9 Nov 2023 14:56:33 +0100
Subject: [PATCH] clarify the max size of the CMSG buffer

---
 quinn-udp/src/windows.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/quinn-udp/src/windows.rs b/quinn-udp/src/windows.rs
index 0fa32344bc..d3e39db9a4 100644
--- a/quinn-udp/src/windows.rs
+++ b/quinn-udp/src/windows.rs
@@ -14,7 +14,8 @@ use crate::EcnCodepoint;
 
 use super::{cmsg, log_sendmsg_error, RecvMeta, Transmit, UdpSockRef, IO_ERROR_LOG_INTERVAL};
 
-const CMSG_LEN: usize = 128; // FIXME arbitrary value, same as unix ?, is it too small/much ?
+// Enough to store max(IP_PKTINFO + IP_ECN, IPV6_PKTINFO + IPV6_ECN) bytes (header + data) and some extra margin
+const CMSG_LEN: usize = 128;
 
 // FIXME this could use [`std::sync::OnceLock`] once the MSRV is bumped to 1.70 and upper
 static WSARECVMSG_PTR: OnceCell<WinSock::LPFN_WSARECVMSG> = OnceCell::new();