From 261e0223a76118efd8cc3c3239f9ca3dc874f45c Mon Sep 17 00:00:00 2001
From: Sven Rebhan <36194019+srebhan@users.noreply.github.com>
Date: Fri, 30 Jun 2023 20:49:26 +0200
Subject: [PATCH] fix(inputs.opcua): Ensure we are connected after reconnect
 (#13514)

---
 plugins/common/opcua/client.go      | 44 ++++++++++++++---------------
 plugins/inputs/opcua/read_client.go | 23 +++++++--------
 2 files changed, 32 insertions(+), 35 deletions(-)

diff --git a/plugins/common/opcua/client.go b/plugins/common/opcua/client.go
index 3a844440d..412d108c9 100644
--- a/plugins/common/opcua/client.go
+++ b/plugins/common/opcua/client.go
@@ -18,6 +18,20 @@ type OpcUAWorkarounds struct {
 	AdditionalValidStatusCodes []string `toml:"additional_valid_status_codes"`
 }
 
+type ConnectionState opcua.ConnState
+
+const (
+	Closed       ConnectionState = ConnectionState(opcua.Closed)
+	Connected    ConnectionState = ConnectionState(opcua.Connected)
+	Connecting   ConnectionState = ConnectionState(opcua.Connecting)
+	Disconnected ConnectionState = ConnectionState(opcua.Disconnected)
+	Reconnecting ConnectionState = ConnectionState(opcua.Reconnecting)
+)
+
+func (c ConnectionState) String() string {
+	return opcua.ConnState(c).String()
+}
+
 type OpcUAClientConfig struct {
 	Endpoint       string          `toml:"endpoint"`
 	SecurityPolicy string          `toml:"security_policy"`
@@ -73,29 +87,15 @@ func (o *OpcUAClientConfig) CreateClient(log telegraf.Logger) (*OpcUAClient, err
 		Log:    log,
 	}
 	c.Log.Debug("Initialising OpcUAClient")
-	c.State = Disconnected
 
 	err = c.setupWorkarounds()
 	return c, err
 }
 
-// ConnectionState used for constants
-type ConnectionState int
-
-const (
-	// Disconnected constant State 0
-	Disconnected ConnectionState = iota
-	// Connecting constant State 1
-	Connecting
-	// Connected constant State 2
-	Connected
-)
-
 type OpcUAClient struct {
 	Config *OpcUAClientConfig
 	Log    telegraf.Logger
 
-	State  ConnectionState
 	Client *opcua.Client
 
 	opts  []opcua.Option
@@ -164,10 +164,7 @@ func (o *OpcUAClient) Connect() error {
 
 	switch u.Scheme {
 	case "opc.tcp":
-		o.State = Connecting
-
-		err = o.SetupOptions()
-		if err != nil {
+		if err := o.SetupOptions(); err != nil {
 			return err
 		}
 
@@ -184,11 +181,8 @@ func (o *OpcUAClient) Connect() error {
 		ctx, cancel := context.WithTimeout(context.Background(), time.Duration(o.Config.ConnectTimeout))
 		defer cancel()
 		if err := o.Client.Connect(ctx); err != nil {
-			o.State = Disconnected
 			return fmt.Errorf("error in Client Connection: %w", err)
 		}
-
-		o.State = Connected
 		o.Log.Debug("Connected to OPC UA Server")
 
 	default:
@@ -206,7 +200,6 @@ func (o *OpcUAClient) Disconnect(ctx context.Context) error {
 
 	switch u.Scheme {
 	case "opc.tcp":
-		o.State = Disconnected
 		// We can't do anything about failing to close a connection
 		err := o.Client.CloseWithContext(ctx)
 		o.Client = nil
@@ -215,3 +208,10 @@ func (o *OpcUAClient) Disconnect(ctx context.Context) error {
 		return fmt.Errorf("invalid controller")
 	}
 }
+
+func (o *OpcUAClient) State() ConnectionState {
+	if o.Client == nil {
+		return Disconnected
+	}
+	return ConnectionState(o.Client.State())
+}
diff --git a/plugins/inputs/opcua/read_client.go b/plugins/inputs/opcua/read_client.go
index 605916d0e..4bbb566c3 100644
--- a/plugins/inputs/opcua/read_client.go
+++ b/plugins/inputs/opcua/read_client.go
@@ -90,29 +90,26 @@ func (o *ReadClient) Connect() error {
 }
 
 func (o *ReadClient) ensureConnected() error {
-	if o.State == opcua.Disconnected {
-		err := o.Connect()
-		if err != nil {
-			return err
-		}
+	if o.State() == opcua.Disconnected {
+		return o.Connect()
 	}
-
 	return nil
 }
 
 func (o *ReadClient) CurrentValues() ([]telegraf.Metric, error) {
-	err := o.ensureConnected()
-	if err != nil {
+	if err := o.ensureConnected(); err != nil {
 		return nil, err
 	}
 
-	err = o.read()
-	if err != nil && o.State == opcua.Connected {
+	if state := o.State(); state != opcua.Connected {
+		return nil, fmt.Errorf("not connected, in state %q", state)
+	}
+
+	if err := o.read(); err != nil {
 		// We do not return the disconnect error, as this would mask the
 		// original problem, but we do log it
-		disconnectErr := o.Disconnect(context.Background())
-		if disconnectErr != nil {
-			o.Log.Debug("Error while disconnecting: ", disconnectErr)
+		if derr := o.Disconnect(context.Background()); derr != nil {
+			o.Log.Debug("Error while disconnecting: ", derr)
 		}
 
 		return nil, err