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bitcoind_conn.go
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bitcoind_conn.go
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package chain
import (
"bytes"
"fmt"
"io"
"net"
"sync"
"sync/atomic"
"time"
"github.com/btcsuite/btcd/btcjson"
"github.com/btcsuite/btcd/chaincfg"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/rpcclient"
"github.com/btcsuite/btcd/wire"
"github.com/lightninglabs/gozmq"
"github.com/lightningnetwork/lnd/ticker"
)
const (
// rawBlockZMQCommand is the command used to receive raw block
// notifications from bitcoind through ZMQ.
rawBlockZMQCommand = "rawblock"
// rawTxZMQCommand is the command used to receive raw transaction
// notifications from bitcoind through ZMQ.
rawTxZMQCommand = "rawtx"
// maxRawBlockSize is the maximum size in bytes for a raw block received
// from bitcoind through ZMQ.
maxRawBlockSize = 4e6
// maxRawTxSize is the maximum size in bytes for a raw transaction
// received from bitcoind through ZMQ.
maxRawTxSize = maxRawBlockSize
// seqNumLen is the length of the sequence number of a message sent from
// bitcoind through ZMQ.
seqNumLen = 4
// errBlockPrunedStr is the error message returned by bitcoind upon
// calling GetBlock on a pruned block.
errBlockPrunedStr = "Block not available (pruned data)"
)
// BitcoindConfig contains all of the parameters required to establish a
// connection to a bitcoind's RPC.
type BitcoindConfig struct {
// ChainParams are the chain parameters the bitcoind server is running
// on.
ChainParams *chaincfg.Params
// Host is the IP address and port of the bitcoind's RPC server.
Host string
// User is the username to use to authenticate to bitcoind's RPC server.
User string
// Pass is the passphrase to use to authenticate to bitcoind's RPC
// server.
Pass string
// ZMQBlockHost is the IP address and port of the bitcoind's rawblock
// listener.
ZMQBlockHost string
// ZMQTxHost is the IP address and port of the bitcoind's rawtx
// listener.
ZMQTxHost string
// ZMQReadDeadline represents the read deadline we'll apply when reading
// ZMQ messages from either subscription.
ZMQReadDeadline time.Duration
// Dialer is a closure we'll use to dial Bitcoin peers. If the chain
// backend is running over Tor, this must support dialing peers over Tor
// as well.
Dialer Dialer
// PrunedModeMaxPeers is the maximum number of peers we'll attempt to
// retrieve pruned blocks from.
//
// NOTE: This only applies for pruned bitcoind nodes.
PrunedModeMaxPeers int
}
// BitcoindConn represents a persistent client connection to a bitcoind node
// that listens for events read from a ZMQ connection.
type BitcoindConn struct {
started int32 // To be used atomically.
stopped int32 // To be used atomically.
// rescanClientCounter is an atomic counter that assigns a unique ID to
// each new bitcoind rescan client using the current bitcoind
// connection.
rescanClientCounter uint64
cfg BitcoindConfig
// client is the RPC client to the bitcoind node.
client *rpcclient.Client
// prunedBlockDispatcher handles all of the pruned block requests.
//
// NOTE: This is nil when the bitcoind node is not pruned.
prunedBlockDispatcher *PrunedBlockDispatcher
// zmqBlockConn is the ZMQ connection we'll use to read raw block
// events.
zmqBlockConn *gozmq.Conn
// zmqTxConn is the ZMQ connection we'll use to read raw transaction
// events.
zmqTxConn *gozmq.Conn
// rescanClients is the set of active bitcoind rescan clients to which
// ZMQ event notfications will be sent to.
rescanClientsMtx sync.Mutex
rescanClients map[uint64]*BitcoindClient
quit chan struct{}
wg sync.WaitGroup
}
// Dialer represents a way to dial Bitcoin peers. If the chain backend is
// running over Tor, this must support dialing peers over Tor as well.
type Dialer = func(string) (net.Conn, error)
// NewBitcoindConn creates a client connection to the node described by the host
// string. The ZMQ connections are established immediately to ensure liveness.
// If the remote node does not operate on the same bitcoin network as described
// by the passed chain parameters, the connection will be disconnected.
func NewBitcoindConn(cfg *BitcoindConfig) (*BitcoindConn, error) {
clientCfg := &rpcclient.ConnConfig{
Host: cfg.Host,
User: cfg.User,
Pass: cfg.Pass,
DisableAutoReconnect: false,
DisableConnectOnNew: true,
DisableTLS: true,
HTTPPostMode: true,
}
client, err := rpcclient.New(clientCfg, nil)
if err != nil {
return nil, err
}
// Verify that the node is running on the expected network.
var net wire.BitcoinNet
btcInWarmup := false
for {
net, err = getCurrentNet(client)
if err == nil {
// No error means bitcoind is responsive and we can proceed.
break
}
if rpcErr, ok := err.(*btcjson.RPCError); ok &&
rpcErr.Code == btcjson.ErrRPCInWarmup {
// Error code -28 indicates the bitcoind rpc is warming up.
// We will wait and recheck periodically until rpc is ready.
if !btcInWarmup {
btcInWarmup = true
log.Info("Waiting for bitcoind RPC to finish warming up...")
}
time.Sleep(time.Second * 1)
} else {
return nil, err
}
}
if btcInWarmup {
log.Info("Bitcoind finished warming up and RPC is ready")
}
if net != cfg.ChainParams.Net {
return nil, fmt.Errorf("expected network %v, got %v",
cfg.ChainParams.Net, net)
}
// Check if the node is pruned, as we'll need to perform additional
// operations if so.
chainInfo, err := client.GetBlockChainInfo()
if err != nil {
return nil, fmt.Errorf("unable to determine if bitcoind is "+
"pruned: %v", err)
}
// Establish two different ZMQ connections to bitcoind to retrieve block
// and transaction event notifications. We'll use two as a separation of
// concern to ensure one type of event isn't dropped from the connection
// queue due to another type of event filling it up.
zmqBlockConn, err := gozmq.Subscribe(
cfg.ZMQBlockHost, []string{rawBlockZMQCommand},
cfg.ZMQReadDeadline,
)
if err != nil {
return nil, fmt.Errorf("unable to subscribe for zmq block "+
"events: %v", err)
}
zmqTxConn, err := gozmq.Subscribe(
cfg.ZMQTxHost, []string{rawTxZMQCommand}, cfg.ZMQReadDeadline,
)
if err != nil {
zmqBlockConn.Close()
return nil, fmt.Errorf("unable to subscribe for zmq tx "+
"events: %v", err)
}
// Only initialize the PrunedBlockDispatcher when the connected bitcoind
// node is pruned.
var prunedBlockDispatcher *PrunedBlockDispatcher
if chainInfo.Pruned {
prunedBlockDispatcher, err = NewPrunedBlockDispatcher(
&PrunedBlockDispatcherConfig{
ChainParams: cfg.ChainParams,
NumTargetPeers: cfg.PrunedModeMaxPeers,
Dial: cfg.Dialer,
GetPeers: client.GetPeerInfo,
GetNodeAddresses: client.GetNodeAddresses,
PeerReadyTimeout: defaultPeerReadyTimeout,
RefreshPeersTicker: ticker.New(defaultRefreshPeersInterval),
MaxRequestInvs: wire.MaxInvPerMsg,
},
)
if err != nil {
return nil, err
}
}
return &BitcoindConn{
cfg: *cfg,
client: client,
prunedBlockDispatcher: prunedBlockDispatcher,
zmqBlockConn: zmqBlockConn,
zmqTxConn: zmqTxConn,
rescanClients: make(map[uint64]*BitcoindClient),
quit: make(chan struct{}),
}, nil
}
// Start attempts to establish a RPC and ZMQ connection to a bitcoind node. If
// successful, a goroutine is spawned to read events from the ZMQ connection.
// It's possible for this function to fail due to a limited number of connection
// attempts. This is done to prevent waiting forever on the connection to be
// established in the case that the node is down.
func (c *BitcoindConn) Start() error {
if !atomic.CompareAndSwapInt32(&c.started, 0, 1) {
return nil
}
// If we're connected to a pruned backend, we'll need to also start our
// pruned block dispatcher to handle pruned block requests.
if c.prunedBlockDispatcher != nil {
log.Debug("Detected pruned bitcoind backend")
if err := c.prunedBlockDispatcher.Start(); err != nil {
return err
}
}
c.wg.Add(2)
go c.blockEventHandler()
go c.txEventHandler()
return nil
}
// Stop terminates the RPC and ZMQ connection to a bitcoind node and removes any
// active rescan clients.
func (c *BitcoindConn) Stop() {
if !atomic.CompareAndSwapInt32(&c.stopped, 0, 1) {
return
}
for _, client := range c.rescanClients {
client.Stop()
}
close(c.quit)
c.client.Shutdown()
c.zmqBlockConn.Close()
c.zmqTxConn.Close()
if c.prunedBlockDispatcher != nil {
c.prunedBlockDispatcher.Stop()
}
c.client.WaitForShutdown()
c.wg.Wait()
}
// blockEventHandler reads raw blocks events from the ZMQ block socket and
// forwards them along to the current rescan clients.
//
// NOTE: This must be run as a goroutine.
func (c *BitcoindConn) blockEventHandler() {
defer c.wg.Done()
log.Info("Started listening for bitcoind block notifications via ZMQ "+
"on", c.zmqBlockConn.RemoteAddr())
// Set up the buffers we expect our messages to consume. ZMQ
// messages from bitcoind include three parts: the command, the
// data, and the sequence number.
//
// We'll allocate a fixed data slice that we'll reuse when reading
// blocks from bitcoind through ZMQ. There's no need to recycle this
// slice (zero out) after using it, as further reads will overwrite the
// slice and we'll only be deserializing the bytes needed.
var (
command [len(rawBlockZMQCommand)]byte
seqNum [seqNumLen]byte
data = make([]byte, maxRawBlockSize)
)
for {
// Before attempting to read from the ZMQ socket, we'll make
// sure to check if we've been requested to shut down.
select {
case <-c.quit:
return
default:
}
// Poll an event from the ZMQ socket.
var (
bufs = [][]byte{command[:], data, seqNum[:]}
err error
)
bufs, err = c.zmqBlockConn.Receive(bufs)
if err != nil {
// EOF should only be returned if the connection was
// explicitly closed, so we can exit at this point.
if err == io.EOF {
return
}
// It's possible that the connection to the socket
// continuously times out, so we'll prevent logging this
// error to prevent spamming the logs.
netErr, ok := err.(net.Error)
if ok && netErr.Timeout() {
log.Trace("Re-establishing timed out ZMQ " +
"block connection")
continue
}
log.Errorf("Unable to receive ZMQ %v message: %v",
rawBlockZMQCommand, err)
continue
}
// We have an event! We'll now ensure it is a block event,
// deserialize it, and report it to the different rescan
// clients.
eventType := string(bufs[0])
switch eventType {
case rawBlockZMQCommand:
block := &wire.MsgBlock{}
r := bytes.NewReader(bufs[1])
if err := block.Deserialize(r); err != nil {
log.Errorf("Unable to deserialize block: %v",
err)
continue
}
c.rescanClientsMtx.Lock()
for _, client := range c.rescanClients {
select {
case client.zmqBlockNtfns <- block:
case <-client.quit:
case <-c.quit:
c.rescanClientsMtx.Unlock()
return
}
}
c.rescanClientsMtx.Unlock()
default:
// It's possible that the message wasn't fully read if
// bitcoind shuts down, which will produce an unreadable
// event type. To prevent from logging it, we'll make
// sure it conforms to the ASCII standard.
if eventType == "" || !isASCII(eventType) {
continue
}
log.Warnf("Received unexpected event type from %v "+
"subscription: %v", rawBlockZMQCommand,
eventType)
}
}
}
// txEventHandler reads raw blocks events from the ZMQ block socket and forwards
// them along to the current rescan clients.
//
// NOTE: This must be run as a goroutine.
func (c *BitcoindConn) txEventHandler() {
defer c.wg.Done()
log.Info("Started listening for bitcoind transaction notifications "+
"via ZMQ on", c.zmqTxConn.RemoteAddr())
// Set up the buffers we expect our messages to consume. ZMQ
// messages from bitcoind include three parts: the command, the
// data, and the sequence number.
//
// We'll allocate a fixed data slice that we'll reuse when reading
// transactions from bitcoind through ZMQ. There's no need to recycle
// this slice (zero out) after using it, as further reads will overwrite
// the slice and we'll only be deserializing the bytes needed.
var (
command [len(rawTxZMQCommand)]byte
seqNum [seqNumLen]byte
data = make([]byte, maxRawTxSize)
)
for {
// Before attempting to read from the ZMQ socket, we'll make
// sure to check if we've been requested to shut down.
select {
case <-c.quit:
return
default:
}
// Poll an event from the ZMQ socket.
var (
bufs = [][]byte{command[:], data, seqNum[:]}
err error
)
bufs, err = c.zmqTxConn.Receive(bufs)
if err != nil {
// EOF should only be returned if the connection was
// explicitly closed, so we can exit at this point.
if err == io.EOF {
return
}
// It's possible that the connection to the socket
// continuously times out, so we'll prevent logging this
// error to prevent spamming the logs.
netErr, ok := err.(net.Error)
if ok && netErr.Timeout() {
log.Trace("Re-establishing timed out ZMQ " +
"transaction connection")
continue
}
log.Errorf("Unable to receive ZMQ %v message: %v",
rawTxZMQCommand, err)
continue
}
// We have an event! We'll now ensure it is a transaction event,
// deserialize it, and report it to the different rescan
// clients.
eventType := string(bufs[0])
switch eventType {
case rawTxZMQCommand:
tx := &wire.MsgTx{}
r := bytes.NewReader(bufs[1])
if err := tx.Deserialize(r); err != nil {
log.Errorf("Unable to deserialize "+
"transaction: %v", err)
continue
}
c.rescanClientsMtx.Lock()
for _, client := range c.rescanClients {
select {
case client.zmqTxNtfns <- tx:
case <-client.quit:
case <-c.quit:
c.rescanClientsMtx.Unlock()
return
}
}
c.rescanClientsMtx.Unlock()
default:
// It's possible that the message wasn't fully read if
// bitcoind shuts down, which will produce an unreadable
// event type. To prevent from logging it, we'll make
// sure it conforms to the ASCII standard.
if eventType == "" || !isASCII(eventType) {
continue
}
log.Warnf("Received unexpected event type from %v "+
"subscription: %v", rawTxZMQCommand, eventType)
}
}
}
// getCurrentNet returns the network on which the bitcoind node is running.
func getCurrentNet(client *rpcclient.Client) (wire.BitcoinNet, error) {
hash, err := client.GetBlockHash(0)
if err != nil {
return 0, err
}
switch *hash {
case *chaincfg.TestNet3Params.GenesisHash:
return chaincfg.TestNet3Params.Net, nil
case *chaincfg.RegressionNetParams.GenesisHash:
return chaincfg.RegressionNetParams.Net, nil
case *chaincfg.SigNetParams.GenesisHash:
return chaincfg.SigNetParams.Net, nil
case *chaincfg.MainNetParams.GenesisHash:
return chaincfg.MainNetParams.Net, nil
default:
return 0, fmt.Errorf("unknown network with genesis hash %v", hash)
}
}
// NewBitcoindClient returns a bitcoind client using the current bitcoind
// connection. This allows us to share the same connection using multiple
// clients.
func (c *BitcoindConn) NewBitcoindClient() *BitcoindClient {
return &BitcoindClient{
quit: make(chan struct{}),
id: atomic.AddUint64(&c.rescanClientCounter, 1),
chainConn: c,
rescanUpdate: make(chan interface{}),
watchedAddresses: make(map[string]struct{}),
watchedOutPoints: make(map[wire.OutPoint]struct{}),
watchedTxs: make(map[chainhash.Hash]struct{}),
notificationQueue: NewConcurrentQueue(20),
zmqTxNtfns: make(chan *wire.MsgTx),
zmqBlockNtfns: make(chan *wire.MsgBlock),
mempool: make(map[chainhash.Hash]struct{}),
expiredMempool: make(map[int32]map[chainhash.Hash]struct{}),
}
}
// AddClient adds a client to the set of active rescan clients of the current
// chain connection. This allows the connection to include the specified client
// in its notification delivery.
//
// NOTE: This function is safe for concurrent access.
func (c *BitcoindConn) AddClient(client *BitcoindClient) {
c.rescanClientsMtx.Lock()
defer c.rescanClientsMtx.Unlock()
c.rescanClients[client.id] = client
}
// RemoveClient removes the client with the given ID from the set of active
// rescan clients. Once removed, the client will no longer receive block and
// transaction notifications from the chain connection.
//
// NOTE: This function is safe for concurrent access.
func (c *BitcoindConn) RemoveClient(id uint64) {
c.rescanClientsMtx.Lock()
defer c.rescanClientsMtx.Unlock()
delete(c.rescanClients, id)
}
// isBlockPrunedErr determines if the error returned by the GetBlock RPC
// corresponds to the requested block being pruned.
func isBlockPrunedErr(err error) bool {
rpcErr, ok := err.(*btcjson.RPCError)
return ok && rpcErr.Code == btcjson.ErrRPCMisc &&
rpcErr.Message == errBlockPrunedStr
}
// GetBlock returns a raw block from the server given its hash. If the server
// has already pruned the block, it will be retrieved from one of its peers.
func (c *BitcoindConn) GetBlock(hash *chainhash.Hash) (*wire.MsgBlock, error) {
block, err := c.client.GetBlock(hash)
// Got the block from the backend successfully, return it.
if err == nil {
return block, nil
}
// We failed getting the block from the backend for whatever reason. If
// it wasn't due to the block being pruned, return the error
// immediately.
if !isBlockPrunedErr(err) || c.prunedBlockDispatcher == nil {
return nil, err
}
// Now that we know the block has been pruned for sure, request it from
// our backend peers.
blockChan, errChan := c.prunedBlockDispatcher.Query(
[]*chainhash.Hash{hash},
)
for {
select {
case block := <-blockChan:
return block, nil
case err := <-errChan:
if err != nil {
return nil, err
}
// errChan fired before blockChan with a nil error, wait
// for the block now.
case <-c.quit:
return nil, ErrBitcoindClientShuttingDown
}
}
}
// isASCII is a helper method that checks whether all bytes in `data` would be
// printable ASCII characters if interpreted as a string.
func isASCII(s string) bool {
for _, c := range s {
if c < 32 || c > 126 {
return false
}
}
return true
}