Add new option -maxorphantx

The option -maxorphantx allows the user to specify the number of
orphan transactions to keep in memory.

Also, lower the default max orphan count from 10000 to 1000.

blockmanager.go

@@ -463,7 +463,7 @@ func (b *blockManager) handleTxMsg(tmsg *txMsg) {
 	// NOTE:  BitcoinJ, and possibly other wallets, don't follow the spec of
 	// sending an inventory message and allowing the remote peer to decide
 	// whether or not they want to request the transaction via a getdata
-	// message.  Unfortuantely the reference implementation permits
+	// message.  Unfortunately, the reference implementation permits
 	// unrequested data, so it has allowed wallets that don't follow the
 	// spec to proliferate.  While this is not ideal, there is no check here
 	// to disconnect peers for sending unsolicited transactions to provide
@@ -471,7 +471,9 @@ func (b *blockManager) handleTxMsg(tmsg *txMsg) {
 
 	// Process the transaction to include validation, insertion in the
 	// memory pool, orphan handling, etc.
-	err := tmsg.peer.server.txMemPool.ProcessTransaction(tmsg.tx, true, true)
+	allowOrphans := cfg.MaxOrphanTxs > 0
+	err := tmsg.peer.server.txMemPool.ProcessTransaction(tmsg.tx,
+		allowOrphans, true)
 
 	// Remove transaction from request maps. Either the mempool/chain
 	// already knows about it and as such we shouldn't have any more

config.go

@@ -106,6 +106,7 @@ type config struct {
 	Upnp               bool          `long:"upnp" description:"Use UPnP to map our listening port outside of NAT"`
 	FreeTxRelayLimit   float64       `long:"limitfreerelay" description:"Limit relay of transactions with no transaction fee to the given amount in thousands of bytes per minute"`
 	NoRelayPriority    bool          `long:"norelaypriority" description:"Do not require free or low-fee transactions to have high priority for relaying"`
+	MaxOrphanTxs       int           `long:"maxorphantx" description:"Max number of orphan transactions to keep in memory"`
 	Generate           bool          `long:"generate" description:"Generate (mine) bitcoins using the CPU"`
 	MiningAddrs        []string      `long:"miningaddr" description:"Add the specified payment address to the list of addresses to use for generated blocks -- At least one address is required if the generate option is set"`
 	BlockMinSize       uint32        `long:"blockminsize" description:"Mininum block size in bytes to be used when creating a block"`
@@ -319,6 +320,7 @@ func loadConfig() (*config, []string, error) {
 		BlockMinSize:      defaultBlockMinSize,
 		BlockMaxSize:      defaultBlockMaxSize,
 		BlockPrioritySize: defaultBlockPrioritySize,
+		MaxOrphanTxs:      maxOrphanTransactions,
 		Generate:          defaultGenerate,
 		AddrIndex:         defaultAddrIndex,
 	}
@@ -600,6 +602,16 @@ func loadConfig() (*config, []string, error) {
 		return nil, nil, err
 	}
 
+	// Limit the max orphan count to a sane vlue.
+	if cfg.MaxOrphanTxs < 0 {
+		str := "%s: The maxorphantx option may not be less than 0 " +
+			"-- parsed [%d]"
+		err := fmt.Errorf(str, funcName, cfg.MaxOrphanTxs)
+		fmt.Fprintln(os.Stderr, err)
+		fmt.Fprintln(os.Stderr, usageMessage)
+		return nil, nil, err
+	}
+
 	// Limit the block priority and minimum block sizes to max block size.
 	cfg.BlockPrioritySize = minUint32(cfg.BlockPrioritySize, cfg.BlockMaxSize)
 	cfg.BlockMinSize = minUint32(cfg.BlockMinSize, cfg.BlockMaxSize)

doc.go

@@ -81,7 +81,8 @@ Application Options:
       --limitfreerelay=    Limit relay of transactions with no transaction fee
                            to the given amount in thousands of bytes per minute
                            (15)
-
+      --maxorphantx=       Max number of orphan transactions to keep in memory
+                           (1000)
       --generate=          Generate (mine) bitcoins using the CPU
       --miningaddr=        Add the specified payment address to the list of
                            addresses to use for generated blocks -- At least

mempool.go

@@ -26,10 +26,8 @@ const (
 	mempoolHeight = 0x7fffffff
 
 	// maxOrphanTransactions is the maximum number of orphan transactions
-	// that can be queued.  At the time this comment was written, this
-	// equates to 10,000 transactions, but will increase if the max allowed
-	// block payload increases.
-	maxOrphanTransactions = wire.MaxBlockPayload / 100
+	// that can be queued.
+	maxOrphanTransactions = 1000
 
 	// maxOrphanTxSize is the maximum size allowed for orphan transactions.
 	// This helps prevent memory exhaustion attacks from sending a lot of
@@ -438,7 +436,7 @@ func (mp *txMemPool) RemoveOrphan(txHash *wire.ShaHash) {
 //
 // This function MUST be called with the mempool lock held (for writes).
 func (mp *txMemPool) limitNumOrphans() error {
-	if len(mp.orphans)+1 > maxOrphanTransactions {
+	if len(mp.orphans)+1 > cfg.MaxOrphanTxs && cfg.MaxOrphanTxs > 0 {
 		// Generate a cryptographically random hash.
 		randHashBytes := make([]byte, wire.HashSize)
 		_, err := rand.Read(randHashBytes)
@@ -503,8 +501,8 @@ func (mp *txMemPool) maybeAddOrphan(tx *btcutil.Tx) error {
 	//
 	// Note that the number of orphan transactions in the orphan pool is
 	// also limited, so this equates to a maximum memory used of
-	// maxOrphanTxSize * maxOrphanTransactions (which is 500MB as of the
-	// time this comment was written).
+	// maxOrphanTxSize * cfg.MaxOrphanTxs (which is ~5MB using the default
+	// values at the time this comment was written).
 	serializedLen := tx.MsgTx().SerializeSize()
 	if serializedLen > maxOrphanTxSize {
 		str := fmt.Sprintf("orphan transaction size of %d bytes is "+

sample-btcd.conf

@@ -203,6 +203,12 @@
 ; the default).
 ; notls=1
 
+; ------------------------------------------------------------------------------
+; Mempool Settings - The following options
+; ------------------------------------------------------------------------------
+; Limit orphan transaction pool to 1000 transactions.
+; maxorphantx=1000
+
 ; ------------------------------------------------------------------------------
 ; Optional Transaction Indexes
 ; ------------------------------------------------------------------------------