[FAB-7397] Peer deliver panic for nonexistent channel

Peer deliver panics when it receives a seek info request for a channel
that does not exist. This CR checks that the channel exists before
accessing the chainSupport for the channel.

Change-Id: I6645285b2197250d5a9318dc07ee38451abe3c75
Signed-off-by: Will Lahti <wtlahti@us.ibm.com>

core/peer/peer.go

@@ -734,6 +734,9 @@ type DeliverSupportManager struct {
 
 func (dsm DeliverSupportManager) GetChain(chainID string) (deliver.Support, bool) {
 	channel, ok := chains.list[chainID]
+	if !ok {
+		return nil, ok
+	}
 	return channel.cs, ok
 }
 

core/peer/peer_test.go

@@ -213,3 +213,18 @@ func TestGetLocalIP(t *testing.T) {
 	ip := GetLocalIP()
 	t.Log(ip)
 }
+
+func TestDeliverSupportManager(t *testing.T) {
+	// reset chains for testing
+	MockInitialize()
+
+	manager := &DeliverSupportManager{}
+	chainSupport, ok := manager.GetChain("fake")
+	assert.Nil(t, chainSupport, "chain support should be nil")
+	assert.False(t, ok, "Should not find fake channel")
+
+	MockCreateChain("testchain")
+	chainSupport, ok = manager.GetChain("testchain")
+	assert.NotNil(t, chainSupport, "chain support should not be nil")
+	assert.True(t, ok, "Should find testchain channel")
+}