Factor out filters to btcutil.

spvsvc/spvchain/db.go

@@ -464,20 +464,21 @@ func createSPVNS(namespace walletdb.Namespace, params *chaincfg.Params) error {
 
 		log.Info("Creating wallet SPV namespace.")
 
-		basicFilter, err := BuildBasicFilter(params.GenesisBlock)
+		basicFilter, err := builder.BuildBasicFilter(
+			params.GenesisBlock)
 		if err != nil {
 			return err
 		}
 
-		basicFilterTip := MakeHeaderForFilter(basicFilter,
+		basicFilterTip := builder.MakeHeaderForFilter(basicFilter,
 			params.GenesisBlock.Header.PrevBlock)
 
-		extFilter, err := BuildExtFilter(params.GenesisBlock)
+		extFilter, err := builder.BuildExtFilter(params.GenesisBlock)
 		if err != nil {
 			return err
 		}
 
-		extFilterTip := MakeHeaderForFilter(extFilter,
+		extFilterTip := builder.MakeHeaderForFilter(extFilter,
 			params.GenesisBlock.Header.PrevBlock)
 
 		err = putBlock(tx, params.GenesisBlock.Header, 0)

spvsvc/spvchain/filter.go

@@ -1,79 +0,0 @@
-package spvchain
-
-import (
-	"github.com/btcsuite/btcd/chaincfg/chainhash"
-	"github.com/btcsuite/btcd/wire"
-	"github.com/btcsuite/btcutil/gcs"
-	"github.com/btcsuite/btcutil/gcs/builder"
-)
-
-// TODO: Move these functions into github.com/btcsuite/btcutil/gcs/builder.
-
-// BuildBasicFilter will be factored out into gcs.builder
-func BuildBasicFilter(block *wire.MsgBlock) (*gcs.Filter, error) {
-	blockHash := block.BlockHash()
-	b := builder.WithKeyHash(&blockHash)
-	_, err := b.Key()
-	if err != nil {
-		str := "failed to create filter builder: %v"
-		return nil, log.Errorf(str, err)
-	}
-	for i, tx := range block.Transactions {
-		// Skip the inputs for the coinbase transaction
-		if i != 0 {
-			for _, txIn := range tx.TxIn {
-				b.AddOutPoint(txIn.PreviousOutPoint)
-			}
-		}
-		for _, txOut := range tx.TxOut {
-			b.AddScript(txOut.PkScript)
-		}
-	}
-	f, err := b.Build()
-	if err != nil {
-		str := "failed to build filter: %v"
-		return nil, log.Errorf(str, err)
-	}
-	return f, nil
-}
-
-// BuildExtFilter will be factored out into gcs.builder
-func BuildExtFilter(block *wire.MsgBlock) (*gcs.Filter, error) {
-	blockHash := block.BlockHash()
-	b := builder.WithKeyHash(&blockHash)
-	_, err := b.Key()
-	if err != nil {
-		str := "failed to create filter builder: %v"
-		return nil, log.Errorf(str, err)
-	}
-	for i, tx := range block.Transactions {
-		txHash := tx.TxHash()
-		b.AddHash(&txHash)
-		// Skip the inputs for the coinbase transaction
-		if i != 0 {
-			for _, txIn := range tx.TxIn {
-				b.AddScript(txIn.SignatureScript)
-			}
-		}
-	}
-	f, err := b.Build()
-	if err != nil {
-		str := "failed to build filter: %v"
-		return nil, log.Errorf(str, err)
-	}
-	return f, nil
-}
-
-// GetFilterHash will be factored out into gcs.builder
-func GetFilterHash(filter *gcs.Filter) chainhash.Hash {
-	return chainhash.HashH(filter.NBytes())
-}
-
-// MakeHeaderForFilter will be factored out into gcs.builder
-func MakeHeaderForFilter(filter *gcs.Filter, prevHeader chainhash.Hash) chainhash.Hash {
-	filterTip := make([]byte, 2*chainhash.HashSize)
-	filterHash := GetFilterHash(filter)
-	copy(filterTip, filterHash[:])
-	copy(filterTip[chainhash.HashSize:], prevHeader[:])
-	return chainhash.HashH(filterTip)
-}

spvsvc/spvchain/spvchain.go

@@ -488,9 +488,9 @@ func (sp *serverPeer) OnAddr(_ *peer.Peer, msg *wire.MsgAddr) {
 func (sp *serverPeer) OnRead(_ *peer.Peer, bytesRead int, msg wire.Message,
 	err error) {
 	sp.server.AddBytesReceived(uint64(bytesRead))
-	// Try to send a message to the subscriber channel if it isn't nil, but
+	// Send a message to each subscriber. Each message gets its own
-	// don't block on failure. Do this inside a goroutine to prevent the
+	// goroutine to prevent blocking on the mutex lock.
-	// server from slowing down too fast.
+	// TODO: Flood control.
 	sp.mtxSubscribers.RLock()
 	defer sp.mtxSubscribers.RUnlock()
 	for subscription := range sp.recvSubscribers {
@@ -1835,7 +1835,7 @@ func (s *ChainService) GetCFilter(blockHash chainhash.Hash,
 					// can ignore this message.
 					return
 				}
-				if MakeHeaderForFilter(gotFilter,
+				if builder.MakeHeaderForFilter(gotFilter,
 					*prevHeader) !=
 					*curHeader {
 					// Filter data doesn't match

spvsvc/spvchain/sync_test.go

@@ -17,6 +17,7 @@ import (
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btclog"
 	"github.com/btcsuite/btcrpcclient"
+	"github.com/btcsuite/btcutil/gcs/builder"
 	"github.com/btcsuite/btcwallet/spvsvc/spvchain"
 	"github.com/btcsuite/btcwallet/waddrmgr"
 	"github.com/btcsuite/btcwallet/walletdb"
@@ -486,7 +487,7 @@ func testRandomBlocks(t *testing.T, svc *spvchain.ChainService,
 				return
 			}
 			// Calculate basic filter from block.
-			calcFilter, err := spvchain.BuildBasicFilter(
+			calcFilter, err := builder.BuildBasicFilter(
 				haveBlock.MsgBlock())
 			if err != nil {
 				errChan <- fmt.Errorf("Couldn't build basic "+
@@ -521,7 +522,7 @@ func testRandomBlocks(t *testing.T, svc *spvchain.ChainService,
 				return
 			}
 			// Check that the filter and header line up.
-			calcHeader := spvchain.MakeHeaderForFilter(calcFilter,
+			calcHeader := builder.MakeHeaderForFilter(calcFilter,
 				*prevHeader)
 			if !bytes.Equal(curHeader[:], calcHeader[:]) {
 				errChan <- fmt.Errorf("Filter header doesn't "+
@@ -554,7 +555,7 @@ func testRandomBlocks(t *testing.T, svc *spvchain.ChainService,
 				return
 			}
 			// Calculate extended filter from block
-			calcFilter, err = spvchain.BuildExtFilter(
+			calcFilter, err = builder.BuildExtFilter(
 				haveBlock.MsgBlock())
 			if err != nil {
 				errChan <- fmt.Errorf("Couldn't build extended"+
@@ -591,7 +592,7 @@ func testRandomBlocks(t *testing.T, svc *spvchain.ChainService,
 				return
 			}
 			// Check that the filter and header line up.
-			calcHeader = spvchain.MakeHeaderForFilter(calcFilter,
+			calcHeader = builder.MakeHeaderForFilter(calcFilter,
 				*prevHeader)
 			if !bytes.Equal(curHeader[:], calcHeader[:]) {
 				errChan <- fmt.Errorf("Filter header doesn't "+