From ccb69ea5e289a918acf0546a9d0ddc3bdbe1fe90 Mon Sep 17 00:00:00 2001
From: Kiang <50792067+kiangz@users.noreply.github.com>
Date: Sun, 13 Sep 2026 03:51:59 +0800
Subject: [PATCH] common/buf/readv_windows.go: Fix raw WSARecv blocking thread
 and preventing connection close (#6743)
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https://github.com/XTLS/Xray-core/pull/6743#issuecomment-5647971870

---------

Co-authored-by: 风扇滑翔翼 <Fangliding.fshxy@outlook.com>
---
 common/buf/readv_windows.go | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/common/buf/readv_windows.go b/common/buf/readv_windows.go
index a812ee04b..6b304e0fd 100644
--- a/common/buf/readv_windows.go
+++ b/common/buf/readv_windows.go
@@ -5,7 +5,8 @@ import (
 )
 
 type windowsReader struct {
-	bufs []syscall.WSABuf
+	bufs  []syscall.WSABuf
+	ready bool
 }
 
 func (r *windowsReader) Init(bs []*Buffer) {
@@ -15,6 +16,7 @@ func (r *windowsReader) Init(bs []*Buffer) {
 	for _, b := range bs {
 		r.bufs = append(r.bufs, syscall.WSABuf{Len: uint32(Size), Buf: &b.v[0]})
 	}
+	r.ready = false
 }
 
 func (r *windowsReader) Clear() {
@@ -25,6 +27,14 @@ func (r *windowsReader) Clear() {
 }
 
 func (r *windowsReader) Read(fd uintptr) int32 {
+	// On the first invocation, we return -1 to indicate "not ready"
+	// to make rawConn.Read wait for readability using the runtime's own mechanism
+	// because syscall.WSARecv() is a blocking call when used with nil OVERLAPPED
+	if !r.ready {
+		r.ready = true
+		return -1
+	}
+
 	var nBytes uint32
 	var flags uint32
 	err := syscall.WSARecv(syscall.Handle(fd), &r.bufs[0], uint32(len(r.bufs)), &nBytes, &flags, nil, nil)