From b74c2da53084de1c239903df08d1e5a3ba58cdb1 Mon Sep 17 00:00:00 2001
From: a-f-G-U-C <65810997+a-f-G-U-C@users.noreply.github.com>
Date: Tue, 26 Oct 2021 12:22:34 +0000
Subject: [PATCH 1/2] implement RX_SRC_LOCAL, Position in updatePosition

---
 src/mesh/NodeDB.cpp | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/src/mesh/NodeDB.cpp b/src/mesh/NodeDB.cpp
index dc46b7ae..e5594b21 100644
--- a/src/mesh/NodeDB.cpp
+++ b/src/mesh/NodeDB.cpp
@@ -451,21 +451,29 @@ void NodeDB::updatePosition(uint32_t nodeId, const Position &p, RxSource src)
 {
     NodeInfo *info = getOrCreateNode(nodeId);
 
-    DEBUG_MSG("DB update position node=0x%x time=%u, latI=%d, lonI=%d\n", nodeId, p.time, p.latitude_i, p.longitude_i);
+    if (src == RX_SRC_LOCAL) {
+        // Local packet, fully authoritative
+        DEBUG_MSG("updatePosition LOCAL pos@%x:5, time=%u, latI=%d, lonI=%d\n", 
+                p.pos_timestamp, p.time, p.latitude_i, p.longitude_i);
+        info->position = p;
 
-    // Be careful to only update fields that have been set by the sender
-    // A lot of position reports don't have time populated.  In that case, be careful to not blow away the time we
-    // recorded based on the packet rxTime
-    if (p.time)
-        info->position.time = p.time;
-    if (p.battery_level)
-        info->position.battery_level = p.battery_level;
-    if (p.latitude_i || p.longitude_i) {
-        info->position.latitude_i = p.latitude_i;
-        info->position.longitude_i = p.longitude_i;
+    } else {
+        // Be careful to only update fields that have been set by the REMOTE sender
+        // A lot of position reports don't have time populated.  In that case, be careful to not blow away the time we
+        // recorded based on the packet rxTime
+        DEBUG_MSG("updatePosition REMOTE node=0x%x time=%u, latI=%d, lonI=%d\n", 
+                nodeId, p.time, p.latitude_i, p.longitude_i);
+
+        // First, back up fields that we want to protect from overwrite
+        uint32_t tmp_time = info->position.time;
+
+        // Next, update atomically
+        info->position = p;
+
+        // Last, restore any fields that may have been overwritten
+        if (! info->position.time)
+            info->position.time = tmp_time;
     }
-    if (p.altitude)
-        info->position.altitude = p.altitude;
     info->has_position = true;
     updateGUIforNode = info;
     notifyObservers(true); // Force an update whether or not our node counts have changed

From 24b2fd265796e3cc206972b06f6084e1fe67f21a Mon Sep 17 00:00:00 2001
From: a-f-G-U-C <65810997+a-f-G-U-C@users.noreply.github.com>
Date: Tue, 26 Oct 2021 12:41:44 +0000
Subject: [PATCH 2/2] better sanity check, logging of inbound positions

---
 src/plugins/PositionPlugin.cpp | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/plugins/PositionPlugin.cpp b/src/plugins/PositionPlugin.cpp
index b772954c..5f03ec6b 100644
--- a/src/plugins/PositionPlugin.cpp
+++ b/src/plugins/PositionPlugin.cpp
@@ -18,6 +18,32 @@ bool PositionPlugin::handleReceivedProtobuf(const MeshPacket &mp, Position *pptr
 {
     auto p = *pptr;
 
+    // If inbound message is a replay (or spoof!) of our own messages, do not process
+    // (why use second-hand sources for our own data?)
+    if (nodeDB.getNodeNum() == getFrom(&mp)) {
+        DEBUG_MSG("Ignored an incoming update from MYSELF\n");
+        return false;
+    }
+
+    // Log packet size and list of fields
+    DEBUG_MSG("POSITION node=%08x l=%d %s%s%s%s%s%s%s%s%s%s%s%s%s%s\n", 
+                getFrom(&mp),
+            	mp.decoded.payload.size,
+                p.latitude_i ? "LAT ":"",
+                p.longitude_i ? "LON ":"",
+                p.altitude ? "MSL ":"",
+                p.altitude_hae ? "HAE ":"",
+                p.alt_geoid_sep ? "GEO ":"",
+                p.PDOP ? "PDOP ":"",
+                p.HDOP ? "HDOP ":"",
+                p.VDOP ? "VDOP ":"",
+                p.sats_in_view ? "SIV ":"",
+                p.fix_quality ? "FXQ ":"",
+                p.fix_type ? "FXT ":"",
+                p.pos_timestamp ? "PTS ":"",
+                p.time ? "TIME ":"",
+                p.battery_level ? "BAT ":"");
+
     if (p.time) {
         struct timeval tv;
         uint32_t secs = p.time;
@@ -77,7 +103,6 @@ MeshPacket *PositionPlugin::allocReply()
     if (pos_flags & PositionFlags_POS_TIMESTAMP)
         p.pos_timestamp = node->position.pos_timestamp;
 
-
     // Strip out any time information before sending packets to other nodes - to keep the wire size small (and because other
     // nodes shouldn't trust it anyways) Note: we allow a device with a local GPS to include the time, so that gpsless
     // devices can get time.
@@ -107,17 +132,20 @@ void PositionPlugin::sendOurPosition(NodeNum dest, bool wantReplies)
 
 int32_t PositionPlugin::runOnce()
 {
+    NodeInfo *node = nodeDB.getNode(nodeDB.getNodeNum());
 
     // We limit our GPS broadcasts to a max rate
     uint32_t now = millis();
     if (lastGpsSend == 0 || now - lastGpsSend >= getPref_position_broadcast_secs() * 1000) {
+
         lastGpsSend = now;
 
         // If we changed channels, ask everyone else for their latest info
         bool requestReplies = currentGeneration != radioGeneration;
         currentGeneration = radioGeneration;
 
-        DEBUG_MSG("Sending position to mesh (wantReplies=%d)\n", requestReplies);
+        DEBUG_MSG("Sending pos@%x:6 to mesh (wantReplies=%d)\n", 
+                    node->position.pos_timestamp, requestReplies);
         sendOurPosition(NODENUM_BROADCAST, requestReplies);
     }