From cb5be9530ab162f5e2b53f12e45c58f945cba718 Mon Sep 17 00:00:00 2001
From: zzz <zzz@i2pmail.org>
Date: Sat, 26 Nov 2022 09:31:31 -0500
Subject: [PATCH] SSU2: Avoid rare NPE handling apparent session confirmed
 without inbound state

reported by drzed
---
 .../java/src/net/i2p/router/transport/udp/PacketHandler.java | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/router/java/src/net/i2p/router/transport/udp/PacketHandler.java b/router/java/src/net/i2p/router/transport/udp/PacketHandler.java
index 738acb8be..473e0fb3e 100644
--- a/router/java/src/net/i2p/router/transport/udp/PacketHandler.java
+++ b/router/java/src/net/i2p/router/transport/udp/PacketHandler.java
@@ -852,6 +852,11 @@ class PacketHandler {
                     return false;
                 }
                 type = header.getType();
+                if (type == SSU2Util.SESSION_CONFIRMED_FLAG_BYTE) {
+                    // one in a million decrypt of SSU 1 packet with type/version/netid all correct?
+                    // can't have session confirmed with null state, avoid NPE below
+                    return false;
+                }
             } else {
                 type = SSU2Util.SESSION_REQUEST_FLAG_BYTE;
             }