Fix relax frame-counter mode fCntDown reset on retransmit.

Closes #179.

Author: brocaar

docs/changelog.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 0.17.2
+
+**Bugfixes:**
+
+* Do not reset downlink frame-counter in case of relax frame-counter mode as
+  this would also reset the downlink counter on a re-transmit.
+
 ## 0.17.1
 
 **Features:**

internal/session/session.go

@@ -152,13 +152,15 @@ func GetNodeSessionForPHYPayload(p *redis.Pool, phy lorawan.PHYPayload) (NodeSes
 		// get full FCnt
 		fullFCnt, ok := ValidateAndGetFullFCntUp(ns, macPL.FHDR.FCnt)
 		if !ok {
-			// if RelaxFCnt is turned on, just trust the uplink FCnt
+			// If RelaxFCnt is turned on, just trust the uplink FCnt
 			// this is insecure, but has been requested by many people for
-			// debugging purposes
+			// debugging purposes.
+			// Note that we do not reset the FCntDown as this would reset the
+			// downlink frame-counter on a re-transmit, which is not what we
+			// want.
 			if ns.RelaxFCnt {
 				fullFCnt = macPL.FHDR.FCnt
 				ns.FCntUp = macPL.FHDR.FCnt
-				ns.FCntDown = 0
 
 				// validate if the mic is valid given the FCnt reset
 				micOK, err := phy.ValidateMIC(ns.NwkSKey)

internal/testsuite/uplink_test.go

@@ -427,7 +427,7 @@ func TestUplinkScenarios(t *testing.T) {
 			runUplinkTests(ctx, tests)
 		})
 
-		Convey("Given a set of test-scenarios for relaxt frame-counter mode", func() {
+		Convey("Given a set of test-scenarios for relax frame-counter mode", func() {
 			expectedApplicationPushDataUpNoData := &as.HandleDataUpRequest{
 				AppEUI: ns.AppEUI[:],
 				DevEUI: ns.DevEUI[:],
@@ -461,7 +461,7 @@ func TestUplinkScenarios(t *testing.T) {
 				AppEUI:         ns.AppEUI[:],
 				DevEUI:         ns.DevEUI[:],
 				MaxPayloadSize: 51,
-				FCnt:           0,
+				FCnt:           5,
 			}
 
 			expectedApplicationPushDataUpNoData7 := &as.HandleDataUpRequest{
@@ -497,7 +497,7 @@ func TestUplinkScenarios(t *testing.T) {
 				AppEUI:         ns.AppEUI[:],
 				DevEUI:         ns.DevEUI[:],
 				MaxPayloadSize: 51,
-				FCnt:           0,
+				FCnt:           5,
 			}
 
 			tests := []uplinkTestCase{
@@ -523,7 +523,7 @@ func TestUplinkScenarios(t *testing.T) {
 					ExpectedApplicationHandleDataUp: expectedApplicationPushDataUpNoData7,
 					ExpectedApplicationGetDataDown:  expectedGetDataDown7,
 					ExpectedFCntUp:                  8,
-					ExpectedFCntDown:                0,
+					ExpectedFCntDown:                5,
 					ExpectedEnabledChannels:         []int{0, 1, 2},
 				},
 				{
@@ -548,7 +548,7 @@ func TestUplinkScenarios(t *testing.T) {
 					ExpectedApplicationHandleDataUp: expectedApplicationPushDataUpNoData,
 					ExpectedApplicationGetDataDown:  expectedGetDataDown,
 					ExpectedFCntUp:                  1,
-					ExpectedFCntDown:                0,
+					ExpectedFCntDown:                5,
 					ExpectedEnabledChannels:         []int{0, 1, 2},
 				},
 			}

mkdocs.yml

@@ -15,7 +15,7 @@ pages:
   - changelog.md
 
 extra:
-  version: '0.17.1'
+  version: '0.17.2'
   github:
     download_release: true