gcs: switch basic filter to index prev output scripts of all inputs

gcs/builder/builder.go

@@ -335,9 +335,9 @@ func WithRandomKey() *GCSBuilder {
 }
 
 // BuildBasicFilter builds a basic GCS filter from a block. A basic GCS filter
-// will contain all the previous outpoints spent within a block, as well as the
-// data pushes within all the outputs created within a block.
-func BuildBasicFilter(block *wire.MsgBlock) (*gcs.Filter, error) {
+// will contain all the previous output scripts spent by inputs within a block,
+// as well as the data pushes within all the outputs created within a block.
+func BuildBasicFilter(block *wire.MsgBlock, prevOutScripts [][]byte) (*gcs.Filter, error) {
 	blockHash := block.BlockHash()
 	b := WithKeyHash(&blockHash)
 
@@ -349,18 +349,8 @@ func BuildBasicFilter(block *wire.MsgBlock) (*gcs.Filter, error) {
 	}
 
 	// In order to build a basic filter, we'll range over the entire block,
-	// adding the outpoint data as well as the data pushes within the
-	// pkScript.
-	for i, tx := range block.Transactions {
-		// Skip the inputs for the coinbase transaction
-		if i != 0 {
-			// Each each txin, we'll add a serialized version of
-			// the txid:index to the filters data slices.
-			for _, txIn := range tx.TxIn {
-				b.AddOutPoint(txIn.PreviousOutPoint)
-			}
-		}
-
+	// adding each whole script itself.
+	for _, tx := range block.Transactions {
 		// For each output in a transaction, we'll add each of the
 		// individual data pushes within the script.
 		for _, txOut := range tx.TxOut {
@@ -368,6 +358,12 @@ func BuildBasicFilter(block *wire.MsgBlock) (*gcs.Filter, error) {
 		}
 	}
 
+	// In the second pass, we'll also add all the prevOutScripts
+	// individually as elements.
+	for _, prevScript := range prevOutScripts {
+		b.AddEntry(prevScript)
+	}
+
 	return b.Build()
 }
 

gcs/gcs.go

@@ -175,7 +175,6 @@ func BuildGCSFilter(P uint8, M uint64, key [KeySize]byte, data [][]byte) (*Filte
 // FromBytes deserializes a GCS filter from a known N, P, and serialized filter
 // as returned by Bytes().
 func FromBytes(N uint32, P uint8, M uint64, d []byte) (*Filter, error) {
-
 	// Basic sanity check.
 	if P > 32 {
 		return nil, ErrPTooBig
@@ -287,7 +286,6 @@ func (f *Filter) N() uint32 {
 // Match checks whether a []byte value is likely (within collision probability)
 // to be a member of the set represented by the filter.
 func (f *Filter) Match(key [KeySize]byte, data []byte) (bool, error) {
-
 	// Create a filter bitstream.
 	filterData, err := f.Bytes()
 	if err != nil {
@@ -335,7 +333,6 @@ func (f *Filter) Match(key [KeySize]byte, data []byte) (bool, error) {
 // probability) to be a member of the set represented by the filter faster than
 // calling Match() for each value individually.
 func (f *Filter) MatchAny(key [KeySize]byte, data [][]byte) (bool, error) {
-
 	// Basic sanity check.
 	if len(data) == 0 {
 		return false, nil