rpc+rfq: populate expiry field in SellOder

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

Author: ffranr

rfq/manager.go

@@ -754,12 +754,8 @@ type SellOrder struct {
 	// must agree to pay.
 	PaymentMaxAmt lnwire.MilliSatoshi
 
-	// Expiry is the unix timestamp at which the order expires.
-	//
-	// TODO(ffranr): This is the invoice expiry unix timestamp in seconds.
-	//  We should make use of this field to ensure quotes are valid for the
-	//  duration of the invoice.
-	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

@@ -481,9 +481,11 @@ func (n *Negotiator) HandleOutgoingSellOrder(order SellOrder) {
 
 		if n.cfg.PriceOracle != nil && order.AssetSpecifier.IsSome() {
 			// Query the price oracle for an asking price.
+			//
+			// TODO(ffranr): Pass the SellOrder expiry to the
+			//  price oracle at this point.
 			assetRate, err := n.queryAskFromPriceOracle(
-				order.AssetSpecifier,
-				fn.None[uint64](),
+				order.AssetSpecifier, fn.None[uint64](),
 				fn.Some(order.PaymentMaxAmt),
 				fn.None[rfqmsg.AssetRate](),
 			)
@@ -494,7 +496,7 @@ func (n *Negotiator) HandleOutgoingSellOrder(order SellOrder) {
 				return
 			}
 
-			assetRateHint = fn.Some[rfqmsg.AssetRate](*assetRate)
+			assetRateHint = fn.MaybeSome(assetRate)
 		}
 
 		request, err := rfqmsg.NewSellRequest(

rpcserver.go

@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"math"
 	"net/http"
 	"strings"
 	"sync"
@@ -6423,9 +6424,17 @@ func unmarshalAssetSellOrder(
 			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.SellOrder{
 		AssetSpecifier: assetSpecifier,
 		PaymentMaxAmt:  lnwire.MilliSatoshi(req.PaymentMaxAmt),
+		Expiry:         expiry,
 		Peer:           peer,
 	}, nil
 }