From b9a8683a4bfe9c453313554f8de1e85acb789383 Mon Sep 17 00:00:00 2001
From: Jonathan Bennett <jbennett@incomsystems.biz>
Date: Mon, 26 Aug 2024 15:48:47 -0500
Subject: [PATCH] Mask out random bits when doing queue ordering (#4561)

* Mask out random bits when doing queue ordering

* Parenthesis
---
 src/mesh/MeshPacketQueue.cpp | 7 ++++---
 src/mesh/MeshTypes.h         | 5 +++--
 src/mesh/Router.cpp          | 2 +-
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/mesh/MeshPacketQueue.cpp b/src/mesh/MeshPacketQueue.cpp
index 24756fd2a..f1c6c4ff3 100644
--- a/src/mesh/MeshPacketQueue.cpp
+++ b/src/mesh/MeshPacketQueue.cpp
@@ -20,8 +20,9 @@ bool CompareMeshPacketFunc(const meshtastic_MeshPacket *p1, const meshtastic_Mes
     // If priorities differ, use that
     // for equal priorities, order by id (older packets have higher priority - this will briefly be wrong when IDs roll over but
     // no big deal)
-    return (p1p != p2p) ? (p1p < p2p)         // prefer bigger priorities
-                        : (p1->id >= p2->id); // prefer smaller packet ids
+    return (p1p != p2p)
+               ? (p1p < p2p)                                                 // prefer bigger priorities
+               : ((p1->id & ID_COUNTER_MASK) >= (p2->id & ID_COUNTER_MASK)); // Mask to counter portion, prefer smaller packet ids
 }
 
 MeshPacketQueue::MeshPacketQueue(size_t _maxLen) : maxLen(_maxLen) {}
@@ -127,4 +128,4 @@ bool MeshPacketQueue::replaceLowerPriorityPacket(meshtastic_MeshPacket *p)
 
     std::make_heap(queue.begin(), queue.end(), &CompareMeshPacketFunc);
     return true;
-}
+}
\ No newline at end of file
diff --git a/src/mesh/MeshTypes.h b/src/mesh/MeshTypes.h
index c0919bf5d..1c9099c39 100644
--- a/src/mesh/MeshTypes.h
+++ b/src/mesh/MeshTypes.h
@@ -14,8 +14,9 @@ typedef uint32_t PacketId; // A packet sequence number
     1 // Reserved to only deliver packets over high speed (non-lora) transports, such as MQTT or BLE mesh (not yet implemented)
 #define ERRNO_OK 0
 #define ERRNO_NO_INTERFACES 33
-#define ERRNO_UNKNOWN 32  // pick something that doesn't conflict with RH_ROUTER_ERROR_UNABLE_TO_DELIVER
-#define ERRNO_DISABLED 34 // the interface is disabled
+#define ERRNO_UNKNOWN 32                   // pick something that doesn't conflict with RH_ROUTER_ERROR_UNABLE_TO_DELIVER
+#define ERRNO_DISABLED 34                  // the interface is disabled
+#define ID_COUNTER_MASK (UINT32_MAX >> 22) // mask to select the counter portion of the ID
 
 /*
  * Source of a received message
diff --git a/src/mesh/Router.cpp b/src/mesh/Router.cpp
index bdd8c4e6c..61b1bbfb6 100644
--- a/src/mesh/Router.cpp
+++ b/src/mesh/Router.cpp
@@ -109,7 +109,7 @@ PacketId generatePacketId()
 
     rollingPacketId++;
 
-    rollingPacketId &= UINT32_MAX >> 22;                                   // Mask out the top 22 bits
+    rollingPacketId &= ID_COUNTER_MASK;                                    // Mask out the top 22 bits
     PacketId id = rollingPacketId | random(UINT32_MAX & 0x7fffffff) << 10; // top 22 bits
     LOG_DEBUG("Partially randomized packet id %u\n", id);
     return id;