Socks: Fix buffer full panic when encoding large UDP packets (#5252)

vemneyy · Fangliding · web-flow · commit b16a5f03fe1a · 2025-11-20T12:21:22.000Z
Co-authored-by: 风扇滑翔翼 &lt;Fangliding.fshxy@outlook.com&gt;
diff --git a/proxy/socks/protocol.go b/proxy/socks/protocol.go
@@ -353,6 +353,11 @@ func EncodeUDPPacket(request *protocol.RequestHeader, data []byte) (*buf.Buffer,
 		b.Release()
 		return nil, err
 	}
+	// if data is too large, return an empty buffer (drop too big data)
+	if b.Available() < int32(len(data)) {
+		b.Clear()
+		return b, nil
+	}
 	common.Must2(b.Write(data))
 	return b, nil
 }

Original file line number	Diff line number	Diff line change
`@@ -353,6 +353,11 @@ func EncodeUDPPacket(request protocol.RequestHeader, data []byte) (buf.Buffer,`
`353`	`353`	`b.Release()`
`354`	`354`	`return nil, err`
`355`	`355`	`}`
	`356`	`+ // if data is too large, return an empty buffer (drop too big data)`
	`357`	`+ if b.Available() < int32(len(data)) {`
	`358`	`+ b.Clear()`
	`359`	`+ return b, nil`
	`360`	`+ }`
`356`	`361`	`common.Must2(b.Write(data))`
`357`	`362`	`return b, nil`
`358`	`363`	`}`