Close and retry a RemoteSigner on err (#2923)

* Close and recreate a RemoteSigner on err

* Update changelog

* Address Anton's comments / suggestions:

 - update changelog
 - restart TCPVal
 - shut down on `ErrUnexpectedResponse`

* re-init remote signer client with fresh connection if Ping fails

- add/update TODOs in secret connection
- rename tcp.go -> tcp_client.go, same with ipc to clarify their purpose

* account for `conn returned by waitConnection can be `nil`

- also add TODO about RemoteSigner conn field

* Tests for retrying: IPC / TCP

 - shorter info log on success
 - set conn and use it in tests to close conn

* Tests for retrying: IPC / TCP

 - shorter info log on success
 - set conn and use it in tests to close conn
 - add rwmutex for conn field in IPC

* comments and doc.go

* fix ipc tests. fixes #2677

* use constants for tests

* cleanup some error statements

* fixes #2784, race in tests

* remove print statement

* minor fixes from review

* update comment on sts spec

* cosmetics

* p2p/conn: add failing tests

* p2p/conn: make SecretConnection thread safe

* changelog

* IPCVal signer refactor

- use a .reset() method
- don't use embedded RemoteSignerClient
- guard RemoteSignerClient with mutex
- drop the .conn
- expose Close() on RemoteSignerClient

* apply IPCVal refactor to TCPVal

* remove mtx from RemoteSignerClient

* consolidate IPCVal and TCPVal, fixes #3104

- done in tcp_client.go
- now called SocketVal
- takes a listener in the constructor
- make tcpListener and unixListener contain all the differences

* delete ipc files

* introduce unix and tcp dialer for RemoteSigner

* rename files

- drop tcp_ prefix
- rename priv_validator.go to file.go

* bring back listener options

* fix node

* fix priv_val_server

* fix node test

* minor cleanup and comments

cmd/priv_val_server/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"os"
+	"time"
 
 	"github.com/tendermint/tendermint/crypto/ed25519"
 	cmn "github.com/tendermint/tendermint/libs/common"
@@ -34,13 +35,20 @@ func main() {
 
 	pv := privval.LoadFilePV(*privValKeyPath, *privValStatePath)
 
-	rs := privval.NewRemoteSigner(
-		logger,
-		*chainID,
-		*addr,
-		pv,
-		ed25519.GenPrivKey(),
-	)
+	var dialer privval.Dialer
+	protocol, address := cmn.ProtocolAndAddress(*addr)
+	switch protocol {
+	case "unix":
+		dialer = privval.DialUnixFn(address)
+	case "tcp":
+		connTimeout := 3 * time.Second // TODO
+		dialer = privval.DialTCPFn(address, connTimeout, ed25519.GenPrivKey())
+	default:
+		logger.Error("Unknown protocol", "protocol", protocol)
+		return
+	}
+
+	rs := privval.NewRemoteSigner(logger, *chainID, pv, dialer)
 	err := rs.Start()
 	if err != nil {
 		panic(err)