From 6ce8dc53e79842af71f0b4a360cb65d9eaa1e8f7 Mon Sep 17 00:00:00 2001
From: Hossin Asaadi <hossin.asaadi@gmail.com>
Date: Mon, 7 Sep 2026 22:14:41 +0100
Subject: [PATCH] common/buf/writer.go: Fix buffered writes failing when
 payload exceeds remaining capacity (#6723)

Fixes https://github.com/XTLS/Xray-core/issues/5287
---
 common/buf/writer.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/common/buf/writer.go b/common/buf/writer.go
index 6ff8a6b6b..f14d83c3d 100644
--- a/common/buf/writer.go
+++ b/common/buf/writer.go
@@ -118,7 +118,9 @@ func (w *BufferedWriter) Write(b []byte) (int, error) {
 
 		nBytes, err := w.buffer.Write(b)
 		totalBytes += nBytes
-		if err != nil {
+
+		// ErrBufferFull means a partial write, so flush below and continue
+		if err != nil && err != ErrBufferFull {
 			return totalBytes, err
 		}
 		if !w.buffered || w.buffer.IsFull() {