#41 PLC connection closing

reactor-plc/plc.lua

@@ -197,6 +197,7 @@ end
 function comms_init(id, modem, local_port, server_port, reactor, iss)
     local self = {
         id = id,
+        open = false,
         seq_num = 0,
         r_seq_num = nil,
         modem = modem,
@@ -218,14 +219,29 @@ function comms_init(id, modem, local_port, server_port, reactor, iss)
     -- PRIVATE FUNCTIONS --
 
     local _send = function (msg_type, msg)
-        local s_pkt = comms.scada_packet()
+        if self.open then
-        local r_pkt = comms.rplc_packet()
+            local s_pkt = comms.scada_packet()
+            local r_pkt = comms.rplc_packet()
 
-        r_pkt.make(self.id, msg_type, msg)
+            r_pkt.make(self.id, msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOLS.RPLC, r_pkt.raw_sendable())
+            s_pkt.make(self.seq_num, PROTOCOLS.RPLC, r_pkt.raw_sendable())
 
-        self.modem.transmit(self.s_port, self.l_port, s_pkt.raw_sendable())
+            self.modem.transmit(self.s_port, self.l_port, s_pkt.raw_sendable())
-        self.seq_num = self.seq_num + 1
+            self.seq_num = self.seq_num + 1
+        end
+    end
+
+    local _send_mgmt = function (msg_type, msg)
+        if self.open then
+            local s_pkt = comms.scada_packet()
+            local m_pkt = comms.mgmt_packet()
+
+            m_pkt.make(msg_type, msg)
+            s_pkt.make(self.seq_num, PROTOCOLS.RPLC, m_pkt.raw_sendable())
+
+            self.modem.transmit(self.s_port, self.l_port, s_pkt.raw_sendable())
+            self.seq_num = self.seq_num + 1
+        end
     end
 
     -- variable reactor status information, excluding heating rate
@@ -425,6 +441,9 @@ function comms_init(id, modem, local_port, server_port, reactor, iss)
                 self.r_seq_num = packet.scada_frame.seq_num()
             end
 
+            -- mark connection as open
+            self.open = true
+
             -- feed the watchdog first so it doesn't uhh...eat our packets
             conn_watchdog.feed()
 
@@ -555,19 +574,34 @@ function comms_init(id, modem, local_port, server_port, reactor, iss)
                     log._debug("discarding non-link packet before linked")
                 end
             elseif packet.scada_frame.protocol() == PROTOCOLS.SCADA_MGMT then
-                -- @todo
+                -- handle session close
+                if packet.type == SCADA_MGMT_TYPES.CLOSE then
+                    self.open = false
+                    conn_watchdog.cancel()
+                    unlink()
+                else
+                    log._warning("received unknown SCADA_MGMT packet type " .. packet.type)
+                end
             end
         end
     end
 
     local is_scrammed = function () return self.scrammed end
     local is_linked = function () return self.linked end
+    local is_closed = function () return not self.open end
 
     local unlink = function ()
         self.linked = false
         self.r_seq_num = nil
     end
 
+    local close = function ()
+        self.open = false
+        conn_watchdog.cancel()
+        unlink()
+        _send_mgmt(SCADA_MGMT_TYPES.CLOSE, {})
+    end
+
     return {
         reconnect_modem = reconnect_modem,
         reconnect_reactor = reconnect_reactor,
@@ -579,6 +613,8 @@ function comms_init(id, modem, local_port, server_port, reactor, iss)
         send_iss_alarm = send_iss_alarm,
         is_scrammed = is_scrammed,
         is_linked = is_linked,
-        unlink = unlink
+        is_closed = is_closed,
+        unlink = unlink,
+        close = close
     }
 end

reactor-plc/startup.lua

@@ -12,7 +12,7 @@ os.loadAPI("config.lua")
 os.loadAPI("plc.lua")
 os.loadAPI("threads.lua")
 
-local R_PLC_VERSION = "alpha-v0.4.13"
+local R_PLC_VERSION = "alpha-v0.4.14"
 
 local print = util.print
 local println = util.println

reactor-plc/threads.lua

@@ -169,9 +169,11 @@ function thread__main(smem, init)
 
             -- check for termination request
             if event == "terminate" or ppm.should_terminate() then
+                log._info("terminate requested, main thread exiting")
                 -- iss handles reactor shutdown
                 plc_state.shutdown = true
-                log._info("terminate requested, main thread exiting")
+                -- close connection
+                plc_comms.close()
                 break
             end
         end
@@ -195,6 +197,7 @@ function thread__iss(smem)
 
         local iss_queue   = smem.q.mq_iss
 
+        local was_closed  = true
         local last_update = util.time()
 
         -- thread loop
@@ -203,6 +206,19 @@ function thread__iss(smem)
             
             -- ISS checks
             if plc_state.init_ok then
+                -- SCRAM if no open connection
+                if networked and plc_comms.is_closed() then
+                    plc_state.scram = true
+                    if not was_closed then
+                        was_closed = true
+                        iss.trip_timeout()
+                        println_ts("server connection closed by remote host")
+                        log._warning("server connection closed by remote host")
+                    end
+                else
+                    was_closed = false
+                end
+
                 -- if we tried to SCRAM but failed, keep trying
                 -- in that case, SCRAM won't be called until it reconnects (this is the expected use of this check)
                 if not plc_state.no_reactor and plc_state.scram and reactor.getStatus() then
@@ -217,13 +233,13 @@ function thread__iss(smem)
                 end
 
                 -- check safety (SCRAM occurs if tripped)
-                if not plc_state.degraded then
+                if not plc_state.no_reactor then
                     local iss_tripped, iss_status_string, iss_first = iss.check()
                     plc_state.scram = plc_state.scram or iss_tripped
 
                     if iss_first then
                         println_ts("[ISS] SCRAM! safety trip: " .. iss_status_string)
-                        if networked then
+                        if networked and not plc_state.no_modem then
                             plc_comms.send_iss_alarm(iss_status_string)
                         end
                     end