From 56d0fbe2e5749181a94b8a5d7031c24d3e662ed1 Mon Sep 17 00:00:00 2001
From: xtaci <imap@live.com>
Date: Tue, 10 Dec 2024 14:56:52 +0800
Subject: [PATCH] add handling when callback returns nil

---
 hopper.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/hopper.go b/hopper.go
index 05a1099..2e9a715 100644
--- a/hopper.go
+++ b/hopper.go
@@ -178,6 +178,10 @@ func (l *Listener) clientIn(data []byte, raddr net.Addr) {
 	// onClientIn callback
 	if l.onClientIn != nil {
 		data = l.onClientIn(raddr, data)
+		// blackhole the packet if the callback returns nil
+		if data == nil {
+			return
+		}
 	}
 
 	// encrypt or re-encrypt the packet if crypterOut is set(with new nonce)
@@ -252,6 +256,10 @@ func (l *Listener) switcher() {
 				// onNextHopIn callback
 				if l.onNextHopIn != nil {
 					dataFromProxy = l.onNextHopIn(res.Conn.RemoteAddr(), res.Context.(net.Addr), dataFromProxy)
+					// blackhole the packet if the callback returns nil.
+					if dataFromProxy == nil {
+						continue
+					}
 				}
 
 				// re-encrypt data if crypterIn is set.