rpc+rfq: populate expiry field in BuyOder

Populate the expiry timestamp field in BuyOder and use type
`time.Time`.

Author: ffranr

rfq/manager.go

@@ -689,7 +689,7 @@ func (m *Manager) UpsertAssetBuyOffer(offer BuyOffer) error {
 }
 
 // BuyOrder instructs the RFQ (Request For Quote) system to request a quote from
-// a peer for the acquisition of an asset.
+// one or more peers for the acquisition of an asset.
 //
 // The normal use of a buy order is as follows:
 //  1. Alice, operating a wallet node, wants to receive a Tap asset as payment
@@ -715,8 +715,8 @@ type BuyOrder struct {
 	// be willing to offer.
 	AssetMaxAmt uint64
 
-	// Expiry is the unix timestamp at which the buy order expires.
-	Expiry uint64
+	// Expiry is the time at which the order expires.
+	Expiry time.Time
 
 	// Peer is the peer that the buy order is intended for. This field is
 	// optional.

rfq/negotiator.go

@@ -176,6 +176,9 @@ func (n *Negotiator) HandleOutgoingBuyOrder(buyOrder BuyOrder) error {
 			buyOrder.AssetSpecifier.IsSome() {
 
 			// Query the price oracle for a bid price.
+			//
+			// TODO(ffranr): Pass the BuyOrder expiry to the price
+			//  oracle at this point.
 			assetRate, err := n.queryBidFromPriceOracle(
 				buyOrder.AssetSpecifier,
 				fn.Some(buyOrder.AssetMaxAmt),

rpcserver.go

@@ -6314,10 +6314,17 @@ func unmarshalAssetBuyOrder(
 			err)
 	}
 
+	// Convert expiry unix timestamp in seconds to time.Time.
+	if req.Expiry > math.MaxInt64 {
+		return nil, fmt.Errorf("expiry must be less than or equal to "+
+			"math.MaxInt64 (expiry=%d)", req.Expiry)
+	}
+	expiry := time.Unix(int64(req.Expiry), 0).UTC()
+
 	return &rfq.BuyOrder{
 		AssetSpecifier: assetSpecifier,
 		AssetMaxAmt:    req.AssetMaxAmt,
-		Expiry:         req.Expiry,
+		Expiry:         expiry,
 		Peer:           fn.MaybeSome(peer),
 	}, nil
 }