Fix "transaction spends nonexisting siacoin output" when refreshing c…

…ontracts (#1111)

`UnconfirmedParents` would only ever return direct parents for a txn but
not grandparents and so on. Leading to hosts not knowing about certain
parents yet and txns failing.

internal/node/transactionpool.go

@@ -2,6 +2,7 @@ package node
 
 import (
 	"errors"
+	"slices"
 
 	"go.sia.tech/core/types"
 	"go.sia.tech/renterd/bus"
@@ -41,32 +42,42 @@ func (tp txpool) AcceptTransactionSet(txns []types.Transaction) error {
 }
 
 func (tp txpool) UnconfirmedParents(txn types.Transaction) ([]types.Transaction, error) {
-	pool := tp.Transactions()
+	return unconfirmedParents(txn, tp.Transactions()), nil
+}
+
+func (tp txpool) Subscribe(subscriber modules.TransactionPoolSubscriber) {
+	tp.tp.TransactionPoolSubscribe(subscriber)
+}
+
+func (tp txpool) Close() error {
+	return tp.tp.Close()
+}
+
+func unconfirmedParents(txn types.Transaction, pool []types.Transaction) []types.Transaction {
 	outputToParent := make(map[types.SiacoinOutputID]*types.Transaction)
 	for i, txn := range pool {
 		for j := range txn.SiacoinOutputs {
 			outputToParent[txn.SiacoinOutputID(j)] = &pool[i]
 		}
 	}
 	var parents []types.Transaction
+	txnsToCheck := []*types.Transaction{&txn}
 	seen := make(map[types.TransactionID]bool)
-	for _, sci := range txn.SiacoinInputs {
-		if parent, ok := outputToParent[sci.ParentID]; ok {
-			if txid := parent.ID(); !seen[txid] {
-				seen[txid] = true
-				parents = append(parents, *parent)
+	for len(txnsToCheck) > 0 {
+		nextTxn := txnsToCheck[0]
+		txnsToCheck = txnsToCheck[1:]
+		for _, sci := range nextTxn.SiacoinInputs {
+			if parent, ok := outputToParent[sci.ParentID]; ok {
+				if txid := parent.ID(); !seen[txid] {
+					seen[txid] = true
+					parents = append(parents, *parent)
+					txnsToCheck = append(txnsToCheck, parent)
+				}
 			}
 		}
 	}
-	return parents, nil
-}
-
-func (tp txpool) Subscribe(subscriber modules.TransactionPoolSubscriber) {
-	tp.tp.TransactionPoolSubscribe(subscriber)
-}
-
-func (tp txpool) Close() error {
-	return tp.tp.Close()
+	slices.Reverse(parents)
+	return parents
 }
 
 func NewTransactionPool(tp modules.TransactionPool) bus.TransactionPool {

internal/node/transactionpool_test.go

@@ -0,0 +1,40 @@
+package node
+
+import (
+	"reflect"
+	"testing"
+
+	"go.sia.tech/core/types"
+)
+
+func TestUnconfirmedParents(t *testing.T) {
+	grandparent := types.Transaction{
+		SiacoinOutputs: []types.SiacoinOutput{{}},
+	}
+	parent := types.Transaction{
+		SiacoinInputs: []types.SiacoinInput{
+			{
+				ParentID: grandparent.SiacoinOutputID(0),
+			},
+		},
+		SiacoinOutputs: []types.SiacoinOutput{{}},
+	}
+	txn := types.Transaction{
+		SiacoinInputs: []types.SiacoinInput{
+			{
+				ParentID: parent.SiacoinOutputID(0),
+			},
+		},
+		SiacoinOutputs: []types.SiacoinOutput{{}},
+	}
+	pool := []types.Transaction{grandparent, parent}
+
+	parents := unconfirmedParents(txn, pool)
+	if len(parents) != 2 {
+		t.Fatalf("expected 2 parents, got %v", len(parents))
+	} else if !reflect.DeepEqual(parents[0], grandparent) {
+		t.Fatalf("expected grandparent")
+	} else if !reflect.DeepEqual(parents[1], parent) {
+		t.Fatalf("expected parent")
+	}
+}