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package privval
import (
"errors"
"fmt"
"net"
"sync"
"time"
"github.com/tendermint/tendermint/crypto"
cmn "github.com/tendermint/tendermint/libs/common"
"github.com/tendermint/tendermint/libs/log"
"github.com/tendermint/tendermint/types"
)
const (
defaultConnHeartBeatSeconds = 2
defaultDialRetries = 10
)
// Socket errors.
var (
ErrUnexpectedResponse = errors.New("received unexpected response")
)
var (
connHeartbeat = time.Second * defaultConnHeartBeatSeconds
)
// SocketValOption sets an optional parameter on the SocketVal.
type SocketValOption func(*SocketVal)
// SocketValHeartbeat sets the period on which to check the liveness of the
// connected Signer connections.
func SocketValHeartbeat(period time.Duration) SocketValOption {
return func(sc *SocketVal) { sc.connHeartbeat = period }
}
// SocketVal implements PrivValidator.
// It listens for an external process to dial in and uses
// the socket to request signatures.
type SocketVal struct {
cmn.BaseService
listener net.Listener
// ping
cancelPing chan struct{}
pingTicker *time.Ticker
connHeartbeat time.Duration
// signer is mutable since it can be
// reset if the connection fails.
// failures are detected by a background
// ping routine.
// All messages are request/response, so we hold the mutex
// so only one request/response pair can happen at a time.
// Methods on the underlying net.Conn itself
// are already gorountine safe.
mtx sync.Mutex
signer *RemoteSignerClient
}
// Check that SocketVal implements PrivValidator.
var _ types.PrivValidator = (*SocketVal)(nil)
// NewSocketVal returns an instance of SocketVal.
func NewSocketVal(
logger log.Logger,
listener net.Listener,
) *SocketVal {
sc := &SocketVal{
listener: listener,
connHeartbeat: connHeartbeat,
}
sc.BaseService = *cmn.NewBaseService(logger, "SocketVal", sc)
return sc
}
//--------------------------------------------------------
// Implement PrivValidator
// GetPubKey implements PrivValidator.
func (sc *SocketVal) GetPubKey() crypto.PubKey {
sc.mtx.Lock()
defer sc.mtx.Unlock()
return sc.signer.GetPubKey()
}
// SignVote implements PrivValidator.
func (sc *SocketVal) SignVote(chainID string, vote *types.Vote) error {
sc.mtx.Lock()
defer sc.mtx.Unlock()
return sc.signer.SignVote(chainID, vote)
}
// SignProposal implements PrivValidator.
func (sc *SocketVal) SignProposal(chainID string, proposal *types.Proposal) error {
sc.mtx.Lock()
defer sc.mtx.Unlock()
return sc.signer.SignProposal(chainID, proposal)
}
//--------------------------------------------------------
// More thread safe methods proxied to the signer
// Ping is used to check connection health.
func (sc *SocketVal) Ping() error {
sc.mtx.Lock()
defer sc.mtx.Unlock()
return sc.signer.Ping()
}
// Close closes the underlying net.Conn.
func (sc *SocketVal) Close() {
sc.mtx.Lock()
defer sc.mtx.Unlock()
if sc.signer != nil {
if err := sc.signer.Close(); err != nil {
sc.Logger.Error("OnStop", "err", err)
}
}
if sc.listener != nil {
if err := sc.listener.Close(); err != nil {
sc.Logger.Error("OnStop", "err", err)
}
}
}
//--------------------------------------------------------
// Service start and stop
// OnStart implements cmn.Service.
func (sc *SocketVal) OnStart() error {
if closed, err := sc.reset(); err != nil {
sc.Logger.Error("OnStart", "err", err)
return err
} else if closed {
return fmt.Errorf("listener is closed")
}
// Start a routine to keep the connection alive
sc.cancelPing = make(chan struct{}, 1)
sc.pingTicker = time.NewTicker(sc.connHeartbeat)
go func() {
for {
select {
case <-sc.pingTicker.C:
err := sc.Ping()
if err != nil {
sc.Logger.Error("Ping", "err", err)
if err == ErrUnexpectedResponse {
return
}
closed, err := sc.reset()
if err != nil {
sc.Logger.Error("Reconnecting to remote signer failed", "err", err)
continue
}
if closed {
sc.Logger.Info("listener is closing")
return
}
sc.Logger.Info("Re-created connection to remote signer", "impl", sc)
}
case <-sc.cancelPing:
sc.pingTicker.Stop()
return
}
}
}()
return nil
}
// OnStop implements cmn.Service.
func (sc *SocketVal) OnStop() {
if sc.cancelPing != nil {
close(sc.cancelPing)
}
sc.Close()
}
//--------------------------------------------------------
// Connection and signer management
// waits to accept and sets a new connection.
// connection is closed in OnStop.
// returns true if the listener is closed
// (ie. it returns a nil conn).
func (sc *SocketVal) reset() (closed bool, err error) {
sc.mtx.Lock()
defer sc.mtx.Unlock()
// first check if the conn already exists and close it.
if sc.signer != nil {
if err := sc.signer.Close(); err != nil {
sc.Logger.Error("error closing socket val connection during reset", "err", err)
}
}
// wait for a new conn
conn, err := sc.acceptConnection()
if err != nil {
return false, err
}
// listener is closed
if conn == nil {
return true, nil
}
sc.signer, err = NewRemoteSignerClient(conn)
if err != nil {
// failed to fetch the pubkey. close out the connection.
if err := conn.Close(); err != nil {
sc.Logger.Error("error closing connection", "err", err)
}
return false, err
}
return false, nil
}
// Attempt to accept a connection.
// Times out after the listener's acceptDeadline
func (sc *SocketVal) acceptConnection() (net.Conn, error) {
conn, err := sc.listener.Accept()
if err != nil {
if !sc.IsRunning() {
return nil, nil // Ignore error from listener closing.
}
return nil, err
}
return conn, nil
}