From aa87dfb69e1b839f75132330b53cbc3600c491f7 Mon Sep 17 00:00:00 2001
From: Wiebe Cazemier <wiebe@halfgaar.net>
Date: Wed, 29 Sep 2021 18:02:16 +0200
Subject: [PATCH] Comply with protocol spec to check for non-0 packet ID

---
 mqttpacket.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+), 0 deletions(-)

diff --git a/mqttpacket.cpp b/mqttpacket.cpp
index 6bb5e7e..f729db4 100644
--- a/mqttpacket.cpp
+++ b/mqttpacket.cpp
@@ -425,6 +425,11 @@ void MqttPacket::handleSubscribe()
 
     uint16_t packet_id = readTwoBytesToUInt16();
 
+    if (packet_id == 0)
+    {
+        throw ProtocolError("Packet ID 0 when subscribing is invalid."); // [MQTT-2.3.1-1]
+    }
+
     Authentication &authentication = *ThreadAuth::getAuth();
 
     std::list<char> subs_reponse_codes;
@@ -478,6 +483,11 @@ void MqttPacket::handleUnsubscribe()
 
     uint16_t packet_id = readTwoBytesToUInt16();
 
+    if (packet_id == 0)
+    {
+        throw ProtocolError("Packet ID 0 when unsubscribing is invalid."); // [MQTT-2.3.1-1]
+    }
+
     while (remainingAfterPos() > 0)
     {
         uint16_t topicLength = readTwoBytesToUInt16();
@@ -534,6 +544,11 @@ void MqttPacket::handlePublish()
         packet_id_pos = pos;
         packet_id = readTwoBytesToUInt16();
 
+        if (packet_id == 0)
+        {
+            throw ProtocolError("Packet ID 0 when publishing is invalid."); // [MQTT-2.3.1-1]
+        }
+
         if (qos == 1)
         {
             PubAck pubAck(packet_id);
--
libgit2 0.21.4