program: let post only make if taker limit order is older

programs/drift/src/math/matching.rs

@@ -26,7 +26,7 @@ pub fn is_maker_for_taker(
     if taker_order.post_only || !maker_order.is_resting_limit_order(slot)? {
         Ok(false)
     // can make if taker order isn't resting (market order or limit going through auction)
-    } else if !taker_order.is_resting_limit_order(slot)? {
+    } else if !taker_order.is_resting_limit_order(slot)? || maker_order.post_only {
         Ok(true)
     // otherwise the maker must be older than the taker order
     } else {

sdk/src/dlob/DLOB.ts

@@ -1384,18 +1384,29 @@ export class DLOB {
 		const bidSlot = bidNode.order.slot.add(
 			new BN(bidNode.order.auctionDuration)
 		);
-		if (askSlot.lte(bidSlot) && !bidNode.order.postOnly) {
+
+		if (bidNode.order.postOnly && askNode.order.postOnly) {
+			return undefined;
+		} else if (bidNode.order.postOnly) {
+			return {
+				takerNode: askNode,
+				makerNode: bidNode,
+			};
+		} else if (askNode.order.postOnly) {
 			return {
 				takerNode: bidNode,
 				makerNode: askNode,
 			};
-		} else if (bidSlot.lte(askSlot) && !askNode.order.postOnly) {
+		} else if (askSlot.lte(bidSlot)) {
+			return {
+				takerNode: bidNode,
+				makerNode: askNode,
+			};
+		} else {
 			return {
 				takerNode: askNode,
 				makerNode: bidNode,
 			};
-		} else {
-			return undefined;
 		}
 	}
 

sdk/tests/dlob/test.ts

@@ -5207,7 +5207,8 @@ describe('DLOB Spot Tests', () => {
 		expect(nodesToFillAfter[1].makerNode?.order?.orderId).to.equal(3);
 	});
 
-	it('Test limit orders skipping more recent post onlys', () => {
+	// add back if dlob checks limit order age again
+	it.skip('Test limit orders skipping more recent post onlys', () => {
 		const vAsk = new BN(15);
 		const vBid = new BN(8);