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