Use protobuf Getters to avoid nil reference (#2646)

In the gateway registry, use the proto generated Get… methods to access the proto structures rather than direct field references.
This protects against dereferencing nil pointers for incomplete structures.  Some unit tests added.

Signed-off-by: andrew-coleman <andrew_coleman@uk.ibm.com>

internal/pkg/gateway/api_test.go

@@ -281,6 +281,16 @@ func TestEvaluate(t *testing.T) {
 			},
 			errString: "failed to create new connection: orderer not answering",
 		},
+		{
+			name: "discovery returns incomplete information - no Properties",
+			postSetup: func(t *testing.T, def *preparedTest) {
+				def.discovery.PeersOfChannelReturns([]gdiscovery.NetworkMember{{
+					Endpoint: "localhost:7051",
+					PKIid:    []byte("ill-defined"),
+				}})
+			},
+			errString: "no endorsing peers found for channel",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -428,6 +438,35 @@ func TestEndorse(t *testing.T) {
 			},
 			errString: "peach-melba",
 		},
+		{
+			name: "discovery returns incomplete protos - nil layout",
+			plan: endorsementPlan{
+				"g1": {{endorser: localhostMock, height: 2}},
+			},
+			postSetup: func(t *testing.T, def *preparedTest) {
+				ed := &dp.EndorsementDescriptor{
+					Chaincode: "my_channel",
+					Layouts:   []*dp.Layout{nil},
+				}
+				def.discovery.PeersForEndorsementReturns(ed, nil)
+			},
+			errString: "failed to assemble transaction",
+		},
+		{
+			name: "discovery returns incomplete protos - nil state info",
+			plan: endorsementPlan{
+				"g1": {{endorser: localhostMock, height: 2}},
+			},
+			postSetup: func(t *testing.T, def *preparedTest) {
+				ed := &dp.EndorsementDescriptor{
+					Chaincode:         "my_channel",
+					Layouts:           []*dp.Layout{{QuantitiesByGroup: map[string]uint32{"g1": 1}}},
+					EndorsersByGroups: map[string]*dp.Peers{"g1": {Peers: []*dp.Peer{{StateInfo: nil}}}},
+				}
+				def.discovery.PeersForEndorsementReturns(ed, nil)
+			},
+			errString: "failed to select a set of endorsers that satisfy the endorsement policy",
+		},
 		{
 			name: "process proposal fails",
 			plan: endorsementPlan{

internal/pkg/gateway/registry.go

@@ -69,27 +69,27 @@ func (reg *registry) endorsers(channel string, chaincode string) ([]*endorser, e
 	reg.configLock.RLock()
 	defer reg.configLock.RUnlock()
 
-	for _, layout := range descriptor.Layouts {
+	for _, layout := range descriptor.GetLayouts() {
 		var receivers []*endorserState // The set of peers the client needs to request endorsements from
 		abandonLayout := false
-		for group, quantity := range layout.QuantitiesByGroup {
+		for group, quantity := range layout.GetQuantitiesByGroup() {
 			// Select n remoteEndorsers from each group sorted by block height
 
 			// block heights
 			var groupPeers []*endorserState
-			for _, peer := range descriptor.EndorsersByGroups[group].Peers {
+			for _, peer := range descriptor.GetEndorsersByGroups()[group].GetPeers() {
 				msg := &gossip.GossipMessage{}
-				err := proto.Unmarshal(peer.StateInfo.Payload, msg)
+				err := proto.Unmarshal(peer.GetStateInfo().GetPayload(), msg)
 				if err != nil {
 					return nil, err
 				}
 
-				height := msg.GetStateInfo().Properties.LedgerHeight
-				err = proto.Unmarshal(peer.MembershipInfo.Payload, msg)
+				height := msg.GetStateInfo().GetProperties().GetLedgerHeight()
+				err = proto.Unmarshal(peer.GetMembershipInfo().GetPayload(), msg)
 				if err != nil {
 					return nil, err
 				}
-				endpoint := msg.GetAliveMsg().Membership.Endpoint
+				endpoint := msg.GetAliveMsg().GetMembership().GetEndpoint()
 
 				// find the endorser in the registry for this endpoint
 				var endorser *endorser
@@ -165,7 +165,7 @@ func (reg *registry) endorsersByOrg(channel string, chaincode string) map[string
 	defer reg.configLock.RUnlock()
 
 	for _, member := range members {
-		endpoint := member.Endpoint
+		endpoint := member.PreferredEndpoint()
 		// find the endorser in the registry for this endpoint
 		var endorser *endorser
 		if endpoint == reg.localEndorser.address {
@@ -178,8 +178,8 @@ func (reg *registry) endorsersByOrg(channel string, chaincode string) map[string
 		}
 		for _, installedChaincode := range member.Properties.GetChaincodes() {
 			// only consider the peers that have our chaincode installed
-			if installedChaincode.Name == chaincode {
-				endorsersByOrg[endorser.mspid] = append(endorsersByOrg[endorser.mspid], &endorserState{endorser: endorser, height: member.Properties.LedgerHeight})
+			if installedChaincode.GetName() == chaincode {
+				endorsersByOrg[endorser.mspid] = append(endorsersByOrg[endorser.mspid], &endorserState{endorser: endorser, height: member.Properties.GetLedgerHeight()})
 			}
 		}
 		for _, es := range endorsersByOrg {