rpcserver: add channel checks to RFQ orders

Author: guggero

rpcserver.go

@@ -6340,7 +6340,7 @@ func unmarshalAssetBuyOrder(
 
 // AddAssetBuyOrder upserts a new buy order for the given asset into the RFQ
 // manager. If the order already exists for the given asset, it will be updated.
-func (r *rpcServer) AddAssetBuyOrder(_ context.Context,
+func (r *rpcServer) AddAssetBuyOrder(ctx context.Context,
 	req *rfqrpc.AddAssetBuyOrderRequest) (*rfqrpc.AddAssetBuyOrderResponse,
 	error) {
 
@@ -6354,13 +6354,24 @@ func (r *rpcServer) AddAssetBuyOrder(_ context.Context,
 		return nil, fmt.Errorf("error unmarshalling buy order: %w", err)
 	}
 
-	peerStr := fn.MapOptionZ(
-		buyOrder.Peer, func(peerVertex route.Vertex) string {
-			return peerVertex.String()
-		},
+	// Currently, we require the peer to be specified in the buy order.
+	peer, err := buyOrder.Peer.UnwrapOrErr(
+		fmt.Errorf("buy order peer must be specified"),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	// Check if we have a channel with the peer.
+	err = r.checkPeerChannel(
+		ctx, peer, buyOrder.AssetSpecifier, req.SkipAssetChannelCheck,
 	)
+	if err != nil {
+		return nil, fmt.Errorf("error checking peer channel: %w", err)
+	}
+
 	rpcsLog.Debugf("[AddAssetBuyOrder]: upserting buy order "+
-		"(dest_peer=%s)", peerStr)
+		"(dest_peer=%s)", peer.String())
 
 	// Register an event listener before actually inserting the order, so we
 	// definitely don't miss any responses.
@@ -6402,11 +6413,61 @@ func (r *rpcServer) AddAssetBuyOrder(_ context.Context,
 
 		case <-timeout:
 			return nil, fmt.Errorf("timeout waiting for response "+
-				"(peer=%s)", peerStr)
+				"(peer=%s)", peer.String())
 		}
 	}
 }
 
+// checkPeerChannel checks if there is a channel with the given peer. If the
+// asset channel check is enabled, it will also check if there is a channel with
+// the given asset with the peer.
+func (r *rpcServer) checkPeerChannel(ctx context.Context, peer route.Vertex,
+	specifier asset.Specifier, skipAssetChannelCheck bool) error {
+
+	// We want to make sure there is at least a channel between us and the
+	// peer, otherwise RFQ negotiation doesn't make sense.
+	switch {
+	// For integration tests, we can't create asset channels, so we allow
+	// the asset channel check to be skipped. In this case we simply check
+	// that we have any channel with the peer.
+	case skipAssetChannelCheck:
+		activeChannels, err := r.cfg.Lnd.Client.ListChannels(
+			ctx, true, false,
+		)
+		if err != nil {
+			return fmt.Errorf("unable to fetch channels: %w", err)
+		}
+		peerChannels := fn.Filter(
+			activeChannels, func(c lndclient.ChannelInfo) bool {
+				return c.PubKeyBytes == peer
+			},
+		)
+		if len(peerChannels) == 0 {
+			return fmt.Errorf("no active channel found with peer "+
+				"%x", peer[:])
+		}
+
+	// For any other case, we'll want to make sure there is a channel with
+	// a non-zero balance of the given asset to carry the order.
+	default:
+		assetID, err := specifier.UnwrapIdOrErr()
+		if err != nil {
+			return fmt.Errorf("cannot check asset channel, " +
+				"missing asset ID")
+		}
+
+		// If we don't get an error here, it means we do have an asset
+		// channel with the peer.
+		_, err = r.rfqChannel(ctx, assetID, &peer)
+		if err != nil {
+			return fmt.Errorf("error checking asset channel: %w",
+				err)
+		}
+	}
+
+	return nil
+}
+
 // unmarshalAssetSellOrder unmarshals an asset sell order from the RPC form.
 func unmarshalAssetSellOrder(
 	req *rfqrpc.AddAssetSellOrderRequest) (*rfq.SellOrder, error) {
@@ -6457,7 +6518,7 @@ func unmarshalAssetSellOrder(
 
 // AddAssetSellOrder upserts a new sell order for the given asset into the RFQ
 // manager. If the order already exists for the given asset, it will be updated.
-func (r *rpcServer) AddAssetSellOrder(_ context.Context,
+func (r *rpcServer) AddAssetSellOrder(ctx context.Context,
 	req *rfqrpc.AddAssetSellOrderRequest) (*rfqrpc.AddAssetSellOrderResponse,
 	error) {
 
@@ -6472,13 +6533,24 @@ func (r *rpcServer) AddAssetSellOrder(_ context.Context,
 			err)
 	}
 
-	// Extract peer identifier as a string for logging.
-	peerStr := fn.MapOptionZ(sellOrder.Peer, func(p route.Vertex) string {
-		return p.String()
-	})
+	// Currently, we require the peer to be specified in the buy order.
+	peer, err := sellOrder.Peer.UnwrapOrErr(
+		fmt.Errorf("sell order peer must be specified"),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	// Check if we have a channel with the peer.
+	err = r.checkPeerChannel(
+		ctx, peer, sellOrder.AssetSpecifier, req.SkipAssetChannelCheck,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("error checking peer channel: %w", err)
+	}
 
 	rpcsLog.Debugf("[AddAssetSellOrder]: upserting sell order "+
-		"(dest_peer=%s)", peerStr)
+		"(dest_peer=%s)", peer.String())
 
 	// Register an event listener before actually inserting the order, so we
 	// definitely don't miss any responses.
@@ -6520,7 +6592,7 @@ func (r *rpcServer) AddAssetSellOrder(_ context.Context,
 
 		case <-timeout:
 			return nil, fmt.Errorf("timeout waiting for response "+
-				"from peer %s", peerStr)
+				"from peer %s", peer.String())
 		}
 	}
 }