From 9fadedc0fc43ea222b09ffdc78c56091387c3221 Mon Sep 17 00:00:00 2001
From: Michael Zillgith <michael.zillgith@mz-automation.de>
Date: Sat, 14 Apr 2018 11:16:20 +0200
Subject: [PATCH] - CS104: fixed timeout T2 problem (S message was sent before
 timeout elapsed)

---
 lib60870-C/src/iec60870/cs104/cs104_connection.c | 16 +++++++++++-----
 lib60870-C/src/iec60870/cs104/cs104_slave.c      | 15 ++++++++++-----
 user_guide.adoc                                  |  2 ++
 3 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/lib60870-C/src/iec60870/cs104/cs104_connection.c b/lib60870-C/src/iec60870/cs104/cs104_connection.c
index 5b944d7c..d09b52c5 100644
--- a/lib60870-C/src/iec60870/cs104/cs104_connection.c
+++ b/lib60870-C/src/iec60870/cs104/cs104_connection.c
@@ -88,9 +88,10 @@ struct sCS104_Connection {
     int receiveCount;
     int sendCount;
 
-    bool firstIMessageReceived;
-
     int unconfirmedReceivedIMessages;
+
+    /* timeout T2 handling */
+    bool timeoutT2Trigger;
     uint64_t lastConfirmationTime;
 
     uint64_t nextT3Timeout;
@@ -173,6 +174,9 @@ sendIMessage(CS104_Connection self, Frame frame)
 
     self->sendCount = (self->sendCount + 1) % 32768;
 
+    self->unconfirmedReceivedIMessages = false;
+    self->timeoutT2Trigger = false;
+
     return self->sendCount;
 }
 
@@ -258,7 +262,7 @@ resetConnection(CS104_Connection self)
 
     self->unconfirmedReceivedIMessages = 0;
     self->lastConfirmationTime = 0xffffffffffffffff;
-    self->firstIMessageReceived = false;
+    self->timeoutT2Trigger = false;
 
     self->oldestSentASDU = -1;
     self->newestSentASDU = -1;
@@ -500,8 +504,8 @@ checkMessage(CS104_Connection self, uint8_t* buffer, int msgSize)
 {
     if ((buffer[2] & 1) == 0) { /* I format frame */
 
-        if (self->firstIMessageReceived == false) {
-            self->firstIMessageReceived = true;
+        if (self->timeoutT2Trigger == false) {
+            self->timeoutT2Trigger = true;
             self->lastConfirmationTime = Hal_getTimeInMs(); /* start timeout T2 */
         }
 
@@ -619,6 +623,7 @@ handleTimeouts(CS104_Connection self)
 
             self->lastConfirmationTime = currentTime;
             self->unconfirmedReceivedIMessages = 0;
+            self->timeoutT2Trigger = false;
 
             sendSMessage(self); /* send confirmation message */
         }
@@ -717,6 +722,7 @@ handleConnection(void* parameter)
                     if (self->unconfirmedReceivedIMessages >= self->parameters.w) {
                         self->lastConfirmationTime = Hal_getTimeInMs();
                         self->unconfirmedReceivedIMessages = 0;
+                        self->timeoutT2Trigger = false;
                         sendSMessage(self);
                     }
                 }
diff --git a/lib60870-C/src/iec60870/cs104/cs104_slave.c b/lib60870-C/src/iec60870/cs104/cs104_slave.c
index 1e1a4877..d7cdcb22 100644
--- a/lib60870-C/src/iec60870/cs104/cs104_slave.c
+++ b/lib60870-C/src/iec60870/cs104/cs104_slave.c
@@ -951,7 +951,10 @@ struct sMasterConnection {
     int receiveCount;  /* received messages - sequence counter */
 
     int unconfirmedReceivedIMessages; /* number of unconfirmed messages received */
+
+    /* timeout T2 handling */
     uint64_t lastConfirmationTime; /* timestamp when the last confirmation message (for I messages) was sent */
+    bool timeoutT2Triggered;
 
     uint64_t nextT3Timeout;
     int outstandingTestFRConMessages;
@@ -966,8 +969,6 @@ struct sMasterConnection {
 
     MessageQueue lowPrioQueue;
     HighPriorityASDUQueue highPrioQueue;
-
-    bool firstIMessageReceived;
 };
 
 
@@ -1090,6 +1091,7 @@ sendIMessage(MasterConnection self, uint8_t* buffer, int msgSize)
         DEBUG_PRINT("SEND I (size = %i) N(S) = %i N(R) = %i\n", msgSize, self->sendCount, self->receiveCount);
         self->sendCount = (self->sendCount + 1) % 32768;
         self->unconfirmedReceivedIMessages = 0;
+        self->timeoutT2Triggered = false;
     }
     else
         self->isRunning = false;
@@ -1487,8 +1489,8 @@ handleMessage(MasterConnection self, uint8_t* buffer, int msgSize)
             return false;
         }
 
-        if (self->firstIMessageReceived == false) {
-            self->firstIMessageReceived = true;
+        if (self->timeoutT2Triggered == false) {
+            self->timeoutT2Triggered = true;
             self->lastConfirmationTime = currentTime; /* start timeout T2 */
         }
 
@@ -1739,6 +1741,7 @@ handleTimeouts(MasterConnection self)
         if ((currentTime - self->lastConfirmationTime) >= (uint64_t) (self->slave->conParameters.t2 * 1000)) {
             self->lastConfirmationTime = currentTime;
             self->unconfirmedReceivedIMessages = 0;
+            self->timeoutT2Triggered = false;
             sendSMessage(self);
         }
     }
@@ -1837,6 +1840,8 @@ connectionHandlingThread(void* parameter)
 
                     self->unconfirmedReceivedIMessages = 0;
 
+                    self->timeoutT2Triggered = false;
+
                     sendSMessage(self);
                 }
             }
@@ -1927,7 +1932,7 @@ MasterConnection_create(CS104_Slave slave, Socket socket, MessageQueue lowPrioQu
         self->unconfirmedReceivedIMessages = 0;
         self->lastConfirmationTime = UINT64_MAX;
 
-        self->firstIMessageReceived = false;
+        self->timeoutT2Triggered = false;
 
         self->maxSentASDUs = slave->conParameters.k;
         self->oldestSentASDU = -1;
diff --git a/user_guide.adoc b/user_guide.adoc
index 52fbd64e..52a58ca4 100644
--- a/user_guide.adoc
+++ b/user_guide.adoc
@@ -357,6 +357,8 @@ For *select before operate* the command has to be sent with the _selectCommand_
 
 If the command has been successful the outstation will answer with an ACT_CON response message with the _negative flag_ not set. In case the outstation cannot execute the command it will also answer with an ACT_CON response but with the _negative flag_ set. You can check if this flag is set with the _CS101_ASDU_isNegative_ function used with the received _CS101_ASDU_ instance.
 
+For a CS 104 master a command can be sent the same way by using the _CS104_Master_sendProcessCommandEx_ function.
+
 
 == Slave (server) side programming