From b7c97ea176c6b1f6258f59f41901728fa22b204e Mon Sep 17 00:00:00 2001
From: ptrus <ptrusr@gmail.com>
Date: Fri, 31 Jan 2020 10:40:42 +0100
Subject: [PATCH] go/tendermint/keymanager: error Status() if keymanager
 doesn't exist

---
 .changelog/2628.bugfix.md                       |  4 ++++
 .../tendermint/apps/keymanager/keymanager.go    | 17 +++++++++--------
 .../tendermint/apps/keymanager/state/state.go   |  2 +-
 go/keymanager/api/api.go                        |  4 ++--
 4 files changed, 16 insertions(+), 11 deletions(-)
 create mode 100644 .changelog/2628.bugfix.md

diff --git a/.changelog/2628.bugfix.md b/.changelog/2628.bugfix.md
new file mode 100644
index 00000000000..f244e41c777
--- /dev/null
+++ b/.changelog/2628.bugfix.md
@@ -0,0 +1,4 @@
+go/tendermint/keymanager: error in Status() if keymanager doesn't exist
+
+This fixes panics in the key-manager client if keymanager for the specific
+runtime doesn't exist.
diff --git a/go/consensus/tendermint/apps/keymanager/keymanager.go b/go/consensus/tendermint/apps/keymanager/keymanager.go
index 3610ca0e085..6dd143778f8 100644
--- a/go/consensus/tendermint/apps/keymanager/keymanager.go
+++ b/go/consensus/tendermint/apps/keymanager/keymanager.go
@@ -96,7 +96,15 @@ func (app *keymanagerApplication) onEpochChange(ctx *abci.Context, epoch epochti
 
 		var forceEmit bool
 		oldStatus, err := state.Status(rt.ID)
-		if err != nil {
+		switch err {
+		case nil:
+		case api.ErrNoSuchStatus:
+			// This must be a new key manager runtime.
+			forceEmit = true
+			oldStatus = &api.Status{
+				ID: rt.ID,
+			}
+		default:
 			// This is fatal, as it suggests state corruption.
 			ctx.Logger().Error("failed to query key manager status",
 				"id", rt.ID,
@@ -104,13 +112,6 @@ func (app *keymanagerApplication) onEpochChange(ctx *abci.Context, epoch epochti
 			)
 			return errors.Wrap(err, "failed to query key manager status")
 		}
-		if oldStatus == nil {
-			// This must be a new key manager runtime.
-			forceEmit = true
-			oldStatus = &api.Status{
-				ID: rt.ID,
-			}
-		}
 
 		newStatus := app.generateStatus(ctx, rt, oldStatus, nodes)
 		if forceEmit || !bytes.Equal(cbor.Marshal(oldStatus), cbor.Marshal(newStatus)) {
diff --git a/go/consensus/tendermint/apps/keymanager/state/state.go b/go/consensus/tendermint/apps/keymanager/state/state.go
index 9a9e1c8f575..57c1d0097c9 100644
--- a/go/consensus/tendermint/apps/keymanager/state/state.go
+++ b/go/consensus/tendermint/apps/keymanager/state/state.go
@@ -60,7 +60,7 @@ func (st *ImmutableState) getStatusesRaw() ([][]byte, error) {
 func (st *ImmutableState) Status(id common.Namespace) (*api.Status, error) {
 	_, raw := st.Snapshot.Get(statusKeyFmt.Encode(&id))
 	if raw == nil {
-		return nil, nil
+		return nil, api.ErrNoSuchStatus
 	}
 
 	var status api.Status
diff --git a/go/keymanager/api/api.go b/go/keymanager/api/api.go
index 5a8a5203b47..ca5080f56b2 100644
--- a/go/keymanager/api/api.go
+++ b/go/keymanager/api/api.go
@@ -29,9 +29,9 @@ const (
 )
 
 var (
-	// ErrNoSuchKeyManager is the error returned when a key manager does not
+	// ErrNoSuchStatus is the error returned when a key manager status does not
 	// exist.
-	ErrNoSuchKeyManager = errors.New(ModuleName, 1, "keymanager: no such key manager")
+	ErrNoSuchStatus = errors.New(ModuleName, 1, "keymanager: no such status")
 
 	// TestPublicKey is the insecure hardcoded key manager public key, used
 	// in insecure builds when a RAK is unavailable.