From 416255f41a8a48ad2cf2fa6e6004294a5f895c42 Mon Sep 17 00:00:00 2001
From: Mikayla Fischler <mikayla@ky8.io>
Date: Sat, 23 Apr 2022 21:10:25 -0400
Subject: [PATCH] PLC check sequence numbers, corrected trip time to ms

---
 reactor-plc/plc.lua        | 14 +++++++++++++-
 supervisor/session/plc.lua |  4 ++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/reactor-plc/plc.lua b/reactor-plc/plc.lua
index f0f00b1..64adb88 100644
--- a/reactor-plc/plc.lua
+++ b/reactor-plc/plc.lua
@@ -202,6 +202,7 @@ function comms_init(id, modem, local_port, server_port, reactor, iss)
     local self = {
         id = id,
         seq_num = 0,
+        r_seq_num = nil,
         modem = modem,
         s_port = server_port,
         l_port = local_port,
@@ -363,6 +364,17 @@ function comms_init(id, modem, local_port, server_port, reactor, iss)
     -- handle an RPLC packet
     local handle_packet = function (packet, plc_state)
         if packet ~= nil then
+            -- check sequence number
+            if self.r_seq_num == nil then
+                self.r_seq_num = packet.scada_frame.seq_num()
+            elseif self.r_seq_num >= packet.scada_frame.seq_num() then
+                log._warning("sequence out-of-order: last = " .. self.r_seq_num .. ", new = " .. packet.scada_frame.seq_num())
+                return
+            else
+                self.r_seq_num = packet.scada_frame.seq_num()
+            end
+
+            -- handle packet
             if packet.scada_frame.protocol() == PROTOCOLS.RPLC then
                 if self.linked then
                     if packet.type == RPLC_TYPES.KEEP_ALIVE then
@@ -372,7 +384,7 @@ function comms_init(id, modem, local_port, server_port, reactor, iss)
 
                         if trip_time < 0 then
                             log._warning("PLC KEEP_ALIVE trip time less than 0 (" .. trip_time .. ")") 
-                        elseif trip_time > 1 then
+                        elseif trip_time > 1000 then
                             log._warning("PLC KEEP_ALIVE trip time > 1s (" .. trip_time .. ")")
                         end
 
diff --git a/supervisor/session/plc.lua b/supervisor/session/plc.lua
index 7694ef4..9fbed9b 100644
--- a/supervisor/session/plc.lua
+++ b/supervisor/session/plc.lua
@@ -190,11 +190,11 @@ function new_session(id, for_reactor, in_queue, out_queue)
 
                     if self.last_rtt < 0 then
                         log._warning(log_header .. "PLC KEEP_ALIVE round trip time less than 0 (" .. trip_time .. ")") 
-                    elseif trip_time > 1 then
+                    elseif trip_time > 1000 then
                         log._warning(log_header .. "PLC KEEP_ALIVE round trip time > 1s (" .. trip_time .. ")")
                     end
 
-                    log._debug(log_header .. "RPLC RTT = ".. trip_time)
+                    log._debug(log_header .. "RPLC RTT = ".. trip_time .. "ms")
                 else
                     log._debug(log_header .. "RPLC keep alive packet length mismatch")
                 end