lnrpc: add auth_proof to graph APIs

Added flag include_auth_proof to DescribeGraph, GetNodeInfo, GetChanInfo
and the corresponding lncli commands. With the flag, these APIs add AuthProof
(signatures from the channel announcement) to the returned ChannelEdge.

This is useful to extract this data from the DB.

rpcserver.go

@@ -6736,7 +6736,7 @@ func (r *rpcServer) DescribeGraph(ctx context.Context,
 			return nil
 		}
 
-		edge := marshalDBEdge(edgeInfo, c1, c2)
+		edge := marshalDBEdge(edgeInfo, c1, c2, req.IncludeAuthProof)
 		resp.Edges = append(resp.Edges, edge)
 
 		return nil
@@ -6782,7 +6782,8 @@ func marshalExtraOpaqueData(data []byte) map[uint64][]byte {
 }
 
 func marshalDBEdge(edgeInfo *models.ChannelEdgeInfo,
-	c1, c2 *models.ChannelEdgePolicy) *lnrpc.ChannelEdge {
+	c1, c2 *models.ChannelEdgePolicy,
+	includeAuthProof bool) *lnrpc.ChannelEdge {
 
 	// Make sure the policies match the node they belong to. c1 should point
 	// to the policy for NodeKey1, and c2 for NodeKey2.
@@ -6821,6 +6822,18 @@ func marshalDBEdge(edgeInfo *models.ChannelEdgeInfo,
 		edge.Node2Policy = marshalDBRoutingPolicy(c2)
 	}
 
+	// We do not expect to have an AuthProof for private channels and for
+	// our own public channels for the time between channel funding and
+	// channel announcement.
+	if includeAuthProof && edgeInfo.AuthProof != nil {
+		edge.AuthProof = &lnrpc.ChannelAuthProof{
+			NodeSig1:    edgeInfo.AuthProof.NodeSig1Bytes,
+			BitcoinSig1: edgeInfo.AuthProof.BitcoinSig1Bytes,
+			NodeSig2:    edgeInfo.AuthProof.NodeSig2Bytes,
+			BitcoinSig2: edgeInfo.AuthProof.BitcoinSig2Bytes,
+		}
+	}
+
 	return edge
 }
 
@@ -6946,7 +6959,9 @@ func (r *rpcServer) GetChanInfo(_ context.Context,
 	// Convert the database's edge format into the network/RPC edge format
 	// which couples the edge itself along with the directional node
 	// routing policies of each node involved within the channel.
-	channelEdge := marshalDBEdge(edgeInfo, edge1, edge2)
+	channelEdge := marshalDBEdge(
+		edgeInfo, edge1, edge2, in.IncludeAuthProof,
+	)
 
 	return channelEdge, nil
 }
@@ -6956,6 +6971,11 @@ func (r *rpcServer) GetChanInfo(_ context.Context,
 func (r *rpcServer) GetNodeInfo(ctx context.Context,
 	in *lnrpc.NodeInfoRequest) (*lnrpc.NodeInfo, error) {
 
+	if in.IncludeAuthProof && !in.IncludeChannels {
+		return nil, fmt.Errorf("include_auth_proof depends on " +
+			"include_channels")
+	}
+
 	graph := r.server.graphDB
 
 	// First, parse the hex-encoded public key into a full in-memory public
@@ -7003,7 +7023,9 @@ func (r *rpcServer) GetNodeInfo(ctx context.Context,
 
 				// Convert the database's edge format into the
 				// network/RPC edge format.
-				channelEdge := marshalDBEdge(edge, c1, c2)
+				channelEdge := marshalDBEdge(
+					edge, c1, c2, in.IncludeAuthProof,
+				)
 				channels = append(channels, channelEdge)
 			}