Handling basic unrecoverable errors

Fix #43

auth.go

@@ -18,7 +18,8 @@ func authSASL(socket io.ReadWriter, decoder *xml.Decoder, f StreamFeatures, user
 		}
 	}
 	if !havePlain {
-		return fmt.Errorf("PLAIN authentication is not supported by server: %v", f.Mechanisms.Mechanism)
+		err := fmt.Errorf("PLAIN authentication is not supported by server: %v", f.Mechanisms.Mechanism)
+		return NewConnError(err, true)
 	}
 
 	return authPlain(socket, decoder, user, password)
@@ -41,7 +42,8 @@ func authPlain(socket io.ReadWriter, decoder *xml.Decoder, user string, password
 	case SASLSuccess:
 	case SASLFailure:
 		// v.Any is type of sub-element in failure, which gives a description of what failed.
-		return errors.New("auth failure: " + v.Any.Local)
+		err := errors.New("auth failure: " + v.Any.Local)
+		return NewConnError(err, true)
 	default:
 		return errors.New("expected SASL success or failure, got " + v.Name())
 	}

client.go

@@ -78,17 +78,18 @@ Setting up the client / Checking the parameters
 func NewClient(config Config) (c *Client, err error) {
 	// TODO: If option address is nil, use the Jid domain to compose the address
 	if config.Address, err = checkAddress(config.Address); err != nil {
-		return
+		return nil, NewConnError(err, true)
 	}
 
 	if config.Password == "" {
 		err = errors.New("missing password")
-		return
+		return nil, NewConnError(err, true)
 	}
 
 	// Parse JID
-	if config.parsedJid, err = NewJid(c.config.Jid); err != nil {
-		return
+	if config.parsedJid, err = NewJid(config.Jid); err != nil {
+		err = errors.New("missing jid")
+		return nil, NewConnError(err, true)
 	}
 
 	c = new(Client)

client_manager.go

@@ -1,8 +1,9 @@
 package xmpp // import "gosrc.io/xmpp"
 
 import (
-	"log"
 	"time"
+
+	"golang.org/x/xerrors"
 )
 
 type PostConnect func(c *Client)
@@ -29,7 +30,7 @@ func NewClientManager(client *Client, pc PostConnect) *ClientManager {
 }
 
 // Start launch the connection loop
-func (cm *ClientManager) Start() {
+func (cm *ClientManager) Start() error {
 	cm.Client.Handler = func(e Event) {
 		switch e.State {
 		case StateConnected:
@@ -41,7 +42,8 @@ func (cm *ClientManager) Start() {
 			cm.connect()
 		}
 	}
-	cm.connect()
+
+	return cm.connect()
 }
 
 // Stop cancels pending operations and terminates existing XMPP client.
@@ -52,17 +54,23 @@ func (cm *ClientManager) Stop() {
 }
 
 // connect manages the reconnection loop and apply the define backoff to avoid overloading the server.
-func (cm *ClientManager) connect() {
+func (cm *ClientManager) connect() error {
 	var backoff Backoff // TODO: Group backoff calculation features with connection manager?
 
 	for {
 		var err error
+		// TODO: Make it possible to define logger to log disconnect and reconnection attempts
 		cm.Metrics = initMetrics()
 
 		// TODO: Test for non recoverable errors (invalid username and password) and return an error
 		//   to start caller. We do not want to retry on non recoverable errors.
 		if cm.Client.Session, err = cm.Client.Connect(); err != nil {
-			log.Printf("Connection error: %v\n", err)
+			var actualErr ConnError
+			if xerrors.As(err, &actualErr) {
+				if actualErr.Permanent {
+					return xerrors.Errorf("unrecoverable connect error %w", actualErr)
+				}
+			}
 			backoff.Wait()
 		} else {
 			break
@@ -72,6 +80,7 @@ func (cm *ClientManager) connect() {
 	if cm.PostConnect != nil {
 		cm.PostConnect(cm.Client)
 	}
+	return nil
 }
 
 // Client Metrics

cmd/xmpp_echo/xmpp_echo.go

@@ -23,13 +23,16 @@ func main() {
 
 	client, err := xmpp.NewClient(config)
 	if err != nil {
-		log.Fatal("Error: ", err)
+		log.Fatalf("%+v", err)
 	}
 
 	cm := xmpp.NewClientManager(client, nil)
-	cm.Start()
+	err = cm.Start()
 	// connection can be stopped with cm.Stop()
 	// connection state can be checked by reading cm.Client.CurrentState
+	if err != nil {
+		log.Fatal(err)
+	}
 
 	// Iterator to receive packets coming from our XMPP connection
 	for packet := range client.Recv() {

conn_error.go

@@ -0,0 +1,33 @@
+package xmpp // import "gosrc.io/xmpp"
+
+import (
+	"fmt"
+
+	"golang.org/x/xerrors"
+)
+
+type ConnError struct {
+	frame xerrors.Frame
+	err   error
+	// Permanent will be true if error is not recoverable
+	Permanent bool
+}
+
+func NewConnError(err error, permanent bool) ConnError {
+	return ConnError{err: err, frame: xerrors.Caller(1), Permanent: permanent}
+}
+
+func (e ConnError) Format(s fmt.State, verb rune) {
+	xerrors.FormatError(e, s, verb)
+}
+
+func (e ConnError) FormatError(p xerrors.Printer) error {
+	e.frame.Format(p)
+	return e.err
+}
+
+func (e ConnError) Error() string {
+	return fmt.Sprint(e)
+}
+
+func (e ConnError) Unwrap() error { return e.err }

go.mod

@@ -6,4 +6,5 @@ require (
 	github.com/google/go-cmp v0.2.0
 	github.com/processone/mpg123 v1.0.0
 	github.com/processone/soundcloud v1.0.0
+	golang.org/x/xerrors v0.0.0-20190513163551-3ee3066db522
 )

go.sum

@@ -1,12 +1,10 @@
 github.com/google/go-cmp v0.2.0 h1:+dTQ8DZQJz0Mb/HjFlkptS1FeQ4cWSnN941F8aEG4SQ=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
-github.com/processone/mpg123 v0.0.0-20160212185547-a17074c7ddc0 h1:7Sb9wi06laajixrlpOJACEtAsnbDYlH8/bRTfLKAiF4=
-github.com/processone/mpg123 v0.0.0-20160212185547-a17074c7ddc0/go.mod h1:e9Ud3cx6fZEPqmEYDqjIsRvgFRPvXWhb0H1Cmu+LUtk=
 github.com/processone/mpg123 v1.0.0 h1:o2WOyGZRM255or1Zc/LtF/jARn51B+9aQl72Qace0GA=
 github.com/processone/mpg123 v1.0.0/go.mod h1:X/FeL+h8vD1bYsG9tIWV3M2c4qNTZOficyvPVBP08go=
-github.com/processone/soundcloud v0.0.0-20160217145628-430ee371ebce h1:lDqQi4xGLeS5mZYpVeyle5num0mWdyy37QmsQiFSX1Y=
-github.com/processone/soundcloud v0.0.0-20160217145628-430ee371ebce/go.mod h1:QfHw5V3JsrdJoYH4aD2+lr18v97eA6wyHaV0Zi+FuOI=
 github.com/processone/soundcloud v1.0.0 h1:/+i6+Yveb7Y6IFGDSkesYI+HddblzcRTQClazzVHxoE=
 github.com/processone/soundcloud v1.0.0/go.mod h1:kDLeWpkRtN3C8kIReQdxoiRi92P9xR6yW6qLOJnNWfY=
 golang.org/x/net v0.0.0-20190110200230-915654e7eabc h1:Yx9JGxI1SBhVLFjpAkWMaO1TF+xyqtHLjZpvQboJGiM=
 golang.org/x/net v0.0.0-20190110200230-915654e7eabc/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/xerrors v0.0.0-20190513163551-3ee3066db522 h1:bhOzK9QyoD0ogCnFro1m2mz41+Ib0oOhfJnBp5MR4K4=
+golang.org/x/xerrors v0.0.0-20190513163551-3ee3066db522/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

session.go

@@ -43,7 +43,7 @@ func NewSession(conn net.Conn, o Config) (net.Conn, *Session, error) {
 	}
 
 	if !s.TlsEnabled && !o.Insecure {
-		return nil, nil, errors.New("failed to negotiate TLS")
+		return nil, nil, NewConnError(errors.New("failed to negotiate TLS session"), true)
 	}
 
 	// auth