[Heartbeat] Refactor TCP Monitor

CHANGELOG.next.asciidoc

@@ -112,6 +112,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 *Heartbeat*
 
 - Fixed excessive memory usage introduced in 7.5 due to over-allocating memory for HTTP checks. {pull}15639[15639]
+- Fixed TCP TLS checks to properly validate hostnames, this broke in 7.x and only worked for IP SANs. {pull}17549[17549]
 
 *Journalbeat*
 

heartbeat/hbtest/hbtestutil.go

@@ -153,6 +153,15 @@ func SummaryChecks(up int, down int) validator.Validator {
 	})
 }
 
+func ResolveChecks(ip string) validator.Validator {
+	return lookslike.MustCompile(map[string]interface{}{
+		"resolve": map[string]interface{}{
+			"ip":     ip,
+			"rtt.us": isdef.IsDuration,
+		},
+	})
+}
+
 // SimpleURLChecks returns a check for a simple URL
 // with only a scheme, host, and port
 func SimpleURLChecks(t *testing.T, scheme string, host string, port uint16) validator.Validator {

heartbeat/monitors/active/dialchain/net.go

@@ -45,7 +45,7 @@ import (
 //    }
 //  }
 func TCPDialer(to time.Duration) NetDialer {
-	return netDialer(to)
+	return CreateNetDialer(to)
 }
 
 // UDPDialer creates a new NetDialer with constant event fields and default
@@ -62,10 +62,11 @@ func TCPDialer(to time.Duration) NetDialer {
 //    }
 //  }
 func UDPDialer(to time.Duration) NetDialer {
-	return netDialer(to)
+	return CreateNetDialer(to)
 }
 
-func netDialer(timeout time.Duration) NetDialer {
+// CreateNetDialer returns a NetDialer with the given timeout.
+func CreateNetDialer(timeout time.Duration) NetDialer {
 	return func(event *beat.Event) (transport.Dialer, error) {
 		return makeDialer(func(network, address string) (net.Conn, error) {
 			namespace := ""

heartbeat/monitors/active/dialchain/util.go

@@ -29,15 +29,6 @@ type timer struct {
 	s, e time.Time
 }
 
-// IDLayer creates an empty placeholder layer.
-func IDLayer() Layer {
-	return _idLayer
-}
-
-var _idLayer = Layer(func(event *beat.Event, next transport.Dialer) (transport.Dialer, error) {
-	return next, nil
-})
-
 // ConstAddrLayer introduces a network layer always passing a constant address
 // to the underlying layer.
 func ConstAddrLayer(address string) Layer {

heartbeat/monitors/active/http/task.go

@@ -94,10 +94,8 @@ func newHTTPMonitorIPsJob(
 		return nil, err
 	}
 
-	settings := monitors.MakeHostJobSettings(hostname, config.Mode)
-
 	pingFactory := createPingFactory(config, port, tls, req, body, validator)
-	job, err := monitors.MakeByHostJob(settings, pingFactory)
+	job, err := monitors.MakeByHostJob(hostname, config.Mode, monitors.StdResolver, pingFactory)
 
 	return job, err
 }

heartbeat/monitors/active/icmp/icmp.go

@@ -71,8 +71,7 @@ func create(
 	pingFactory := monitors.MakePingIPFactory(createPingIPFactory(&config))
 
 	for _, host := range config.Hosts {
-		settings := monitors.MakeHostJobSettings(host, config.Mode)
-		job, err := monitors.MakeByHostJob(settings, pingFactory)
+		job, err := monitors.MakeByHostJob(host, config.Mode, monitors.StdResolver, pingFactory)
 
 		if err != nil {
 			return nil, 0, err

heartbeat/monitors/active/tcp/check.go → heartbeat/monitors/active/tcp/datacheck.go

@@ -23,18 +23,20 @@ import (
 	"net"
 )
 
-type ConnCheck func(net.Conn) error
+// dataCheck executes over an open TCP connection using the send / receive
+// parameters the user has defined.
+type dataCheck func(net.Conn) error
 
 var (
 	errNoDataReceived = errors.New("no data")
 	errRecvMismatch   = errors.New("received string mismatch")
 )
 
-func (c ConnCheck) Validate(conn net.Conn) error {
+func (c dataCheck) Check(conn net.Conn) error {
 	return c(conn)
 }
 
-func makeValidateConn(config *Config) ConnCheck {
+func makeDataCheck(config *Config) dataCheck {
 	send := config.SendString
 	recv := config.ReceiveString
 
@@ -52,7 +54,7 @@ func makeValidateConn(config *Config) ConnCheck {
 
 func checkOk(_ net.Conn) error { return nil }
 
-func checkAll(checks ...ConnCheck) ConnCheck {
+func checkAll(checks ...dataCheck) dataCheck {
 	return func(conn net.Conn) error {
 		for _, check := range checks {
 			if err := check(conn); err != nil {
@@ -63,13 +65,13 @@ func checkAll(checks ...ConnCheck) ConnCheck {
 	}
 }
 
-func checkSend(buf []byte) ConnCheck {
+func checkSend(buf []byte) dataCheck {
 	return func(conn net.Conn) error {
 		return sendBuffer(conn, buf)
 	}
 }
 
-func checkRecv(expected []byte) ConnCheck {
+func checkRecv(expected []byte) dataCheck {
 	return func(conn net.Conn) error {
 		buf := make([]byte, len(expected))
 		if err := recvBuffer(conn, buf); err != nil {