Introduce Credential structure to define auth type

For now we are planning to support Password and OAuthToken.
In the future, we would like to add certificate-based authentication.

README.md

@@ -34,7 +34,7 @@ Here is an example code to configure a client to allow connecting to a server wi
 config := xmpp.Config{
 	Address:      "localhost:5222",
 	Jid:          "test@localhost",
-	Password:     "test",
+	Credential:   xmpp.Password("Test"),
 	TLSConfig:    tls.Config{InsecureSkipVerify: true},
 }
 ```
@@ -96,7 +96,7 @@ func main() {
 	config := xmpp.Config{
 		Address:      "localhost:5222",
 		Jid:          "test@localhost",
-		Password:     "test",
+	    Credential:   xmpp.Password("Test"),
 		StreamLogger: os.Stdout,
 		Insecure:     true,
 	}

_examples/xmpp_echo/xmpp_echo.go

@@ -17,7 +17,7 @@ func main() {
 	config := xmpp.Config{
 		Address:      "localhost:5222",
 		Jid:          "test@localhost",
-		Password:     "test",
+		Credential:   xmpp.Password("test"),
 		StreamLogger: os.Stdout,
 		Insecure:     true,
 		// TLSConfig: tls.Config{InsecureSkipVerify: true},

_examples/xmpp_jukebox/xmpp_jukebox.go

@@ -34,7 +34,7 @@ func main() {
 	config := xmpp.Config{
 		Address:    *address,
 		Jid:        *jid,
-		Password: *password,
+		Credential: xmpp.Password(*password),
 		// StreamLogger: os.Stdout,
 		Insecure: true,
 	}

auth.go

@@ -10,8 +10,34 @@ import (
 	"gosrc.io/xmpp/stanza"
 )
 
-func authSASL(socket io.ReadWriter, decoder *xml.Decoder, f stanza.StreamFeatures, user string, password string) (err error) {
+// Credential is used to pass the type of secret that will be used to connect to XMPP server.
-	// TODO: Implement other type of SASL Authentication
+// It can be either a password or an OAuth 2 bearer token.
+type Credential struct {
+	secret     string
+	mechanisms []string
+}
+
+func Password(pwd string) Credential {
+	credential := Credential{
+		secret:     pwd,
+		mechanisms: []string{"PLAIN"},
+	}
+	return credential
+}
+
+func OAuthToken(token string) Credential {
+	credential := Credential{
+		secret:     token,
+		mechanisms: []string{"X-OAUTH2"},
+	}
+	return credential
+}
+
+// ============================================================================
+// Authentication flow for SASL mechanisms
+
+func authSASL(socket io.ReadWriter, decoder *xml.Decoder, f stanza.StreamFeatures, user string, credential Credential) (err error) {
+	// TODO: Implement other type of SASL mechanisms
 	havePlain := false
 	for _, m := range f.Mechanisms.Mechanism {
 		if m == "PLAIN" {
@@ -24,12 +50,12 @@ func authSASL(socket io.ReadWriter, decoder *xml.Decoder, f stanza.StreamFeature
 		return NewConnError(err, true)
 	}
 
-	return authPlain(socket, decoder, user, password)
+	return authPlain(socket, decoder, user, credential)
 }
 
 // Plain authentication: send base64-encoded \x00 user \x00 password
-func authPlain(socket io.ReadWriter, decoder *xml.Decoder, user string, password string) error {
+func authPlain(socket io.ReadWriter, decoder *xml.Decoder, user string, credential Credential) error {
-	raw := "\x00" + user + "\x00" + password
+	raw := "\x00" + user + "\x00" + credential.secret
 	enc := make([]byte, base64.StdEncoding.EncodedLen(len(raw)))
 	base64.StdEncoding.Encode(enc, []byte(raw))
 	fmt.Fprintf(socket, "<auth xmlns='%s' mechanism='PLAIN'>%s</auth>", stanza.NSSASL, enc)

client.go

@@ -111,8 +111,8 @@ func NewClient(config Config, r *Router) (c *Client, err error) {
 		return nil, NewConnError(err, true)
 	}
 
-	if config.Password == "" {
+	if config.Credential.secret == "" {
-		err = errors.New("missing password")
+		err = errors.New("missing credential")
 		return nil, NewConnError(err, true)
 	}
 

client_test.go

@@ -25,7 +25,7 @@ func TestClient_Connect(t *testing.T) {
 	mock.Start(t, testXMPPAddress, handlerConnectSuccess)
 
 	// Test / Check result
-	config := Config{Address: testXMPPAddress, Jid: "test@localhost", Password: "test", Insecure: true}
+	config := Config{Address: testXMPPAddress, Jid: "test@localhost", Credential: Password("test"), Insecure: true}
 
 	var client *Client
 	var err error
@@ -47,7 +47,7 @@ func TestClient_NoInsecure(t *testing.T) {
 	mock.Start(t, testXMPPAddress, handlerAbortTLS)
 
 	// Test / Check result
-	config := Config{Address: testXMPPAddress, Jid: "test@localhost", Password: "test"}
+	config := Config{Address: testXMPPAddress, Jid: "test@localhost", Credential: Password("test")}
 
 	var client *Client
 	var err error
@@ -71,7 +71,7 @@ func TestClient_FeaturesTracking(t *testing.T) {
 	mock.Start(t, testXMPPAddress, handlerAbortTLS)
 
 	// Test / Check result
-	config := Config{Address: testXMPPAddress, Jid: "test@localhost", Password: "test"}
+	config := Config{Address: testXMPPAddress, Jid: "test@localhost", Credential: Password("test")}
 
 	var client *Client
 	var err error
@@ -94,7 +94,7 @@ func TestClient_RFC3921Session(t *testing.T) {
 	mock.Start(t, testXMPPAddress, handlerConnectWithSession)
 
 	// Test / Check result
-	config := Config{Address: testXMPPAddress, Jid: "test@localhost", Password: "test", Insecure: true}
+	config := Config{Address: testXMPPAddress, Jid: "test@localhost", Credential: Password("test"), Insecure: true}
 
 	var client *Client
 	var err error

cmd/fluuxmpp/send.go

@@ -34,7 +34,7 @@ func sendxmpp(cmd *cobra.Command, args []string) {
 	client, err := xmpp.NewClient(xmpp.Config{
 		Jid:        viper.GetString("jid"),
 		Address:    viper.GetString("addr"),
-		Password: viper.GetString("password"),
+		Credential: xmpp.Password(viper.GetString("password")),
 	}, xmpp.NewRouter())
 
 	if err != nil {

cmd/go.sum

@@ -143,6 +143,7 @@ golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 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=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7 h1:9zdDQZ7Thm29KFXgAX/+yaf3eVbP7djjWp/dXAppNCc=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=

config.go

@@ -10,7 +10,7 @@ type Config struct {
 	Address        string
 	Jid            string
 	parsedJid      *Jid // For easier manipulation
-	Password       string
+	Credential     Credential
 	StreamLogger   *os.File // Used for debugging
 	Lang           string   // TODO: should default to 'en'
 	ConnectTimeout int      // Client timeout in seconds. Default to 15

session.go

@@ -168,7 +168,7 @@ func (s *Session) auth(o Config) {
 		return
 	}
 
-	s.err = authSASL(s.streamLogger, s.decoder, s.Features, o.parsedJid.Node, o.Password)
+	s.err = authSASL(s.streamLogger, s.decoder, s.Features, o.parsedJid.Node, o.Credential)
 }
 
 // Attempt to resume session using stream management