Add constants (enumlike) for stanza types and simplify packet creation (#62)

* Add constants (enumlike) for stanza types
* NewIQ, NewMessage and NewPresence are now initialized with the Attrs struct
* Update examples
* Do not export backoff code. For now, we do not need to expose backoff in the documentation
* Make presence priority an int8

_examples/delegation/delegation.go

@@ -83,7 +83,7 @@ func discoInfo(c xmpp.Sender, p xmpp.Packet, opts xmpp.ComponentOptions) {
 		return
 	}
 
-	iqResp := xmpp.NewIQ("result", iq.To, iq.From, iq.Id, "en")
+	iqResp := xmpp.NewIQ(xmpp.Attrs{Type: "result", From: iq.To, To: iq.From, Id: iq.Id})
 
 	switch info.Node {
 	case "":
@@ -192,7 +192,7 @@ func handleDelegation(s xmpp.Sender, p xmpp.Packet) {
 
 	if pubsub.Publish.XMLName.Local == "publish" {
 		// Prepare pubsub IQ reply
-		iqResp := xmpp.NewIQ("result", forwardedIQ.To, forwardedIQ.From, forwardedIQ.Id, "en")
+		iqResp := xmpp.NewIQ(xmpp.Attrs{Type: "result", From: forwardedIQ.To, To: forwardedIQ.From, Id: forwardedIQ.Id})
 		payload := xmpp.PubSub{
 			XMLName: xml.Name{
 				Space: "http://jabber.org/protocol/pubsub",
@@ -201,7 +201,7 @@ func handleDelegation(s xmpp.Sender, p xmpp.Packet) {
 		}
 		iqResp.Payload = &payload
 		// Wrap the reply in delegation 'forward'
-		iqForward := xmpp.NewIQ("result", iq.To, iq.From, iq.Id, "en")
+		iqForward := xmpp.NewIQ(xmpp.Attrs{Type: "result", From: iq.To, To: iq.From, Id: iq.Id})
 		delegPayload := xmpp.Delegation{
 			XMLName: xml.Name{
 				Space: "urn:xmpp:delegation:1",

_examples/go.mod

@@ -8,3 +8,5 @@ require (
 	github.com/processone/soundcloud v1.0.0
 	gosrc.io/xmpp v0.1.1-0.20190619120342-a6cbc0c08f52
 )
+
+replace gosrc.io/xmpp => gosrc.io/xmpp v0.1.1-0.20190619153249-b1dde2330764

_examples/go.sum

@@ -8,4 +8,7 @@ golang.org/x/net v0.0.0-20190110200230-915654e7eabc h1:Yx9JGxI1SBhVLFjpAkWMaO1TF
 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=
+gosrc.io/xmpp v0.1.1-0.20190619120342-a6cbc0c08f52 h1:H5BezaFYvDL9r72ng90ICneftomo1iXx6+BxxZ9jBtg=
 gosrc.io/xmpp v0.1.1-0.20190619120342-a6cbc0c08f52/go.mod h1:WvSgrZF7lMvjd1SH8nVGi7ZGr6gNU7oUuBdwpFTs9nY=
+gosrc.io/xmpp v0.1.1-0.20190619153249-b1dde2330764 h1:jlYtpqdRoBC3Gke7MacXsVpSZL0g5nIBG/b9JVxpAVY=
+gosrc.io/xmpp v0.1.1-0.20190619153249-b1dde2330764/go.mod h1:WvSgrZF7lMvjd1SH8nVGi7ZGr6gNU7oUuBdwpFTs9nY=

_examples/xmpp_component/xmpp_component.go

@@ -59,7 +59,7 @@ func discoInfo(c xmpp.Sender, p xmpp.Packet, opts xmpp.ComponentOptions) {
 		return
 	}
 
-	iqResp := xmpp.NewIQ("result", iq.To, iq.From, iq.Id, "en")
+	iqResp := xmpp.NewIQ(xmpp.Attrs{Type: "result", From: iq.To, To: iq.From, Id: iq.Id, Lang: "en"})
 	identity := xmpp.Identity{
 		Name:     opts.Name,
 		Category: opts.Category,
@@ -95,7 +95,7 @@ func discoItems(c xmpp.Sender, p xmpp.Packet) {
 		return
 	}
 
-	iqResp := xmpp.NewIQ("result", iq.To, iq.From, iq.Id, "en")
+	iqResp := xmpp.NewIQ(xmpp.Attrs{Type: "result", From: iq.To, To: iq.From, Id: iq.Id, Lang: "en"})
 
 	var payload xmpp.DiscoItems
 	if discoItems.Node == "" {
@@ -116,7 +116,7 @@ func handleVersion(c xmpp.Sender, p xmpp.Packet) {
 		return
 	}
 
-	iqResp := xmpp.NewIQ("result", iq.To, iq.From, iq.Id, "en")
+	iqResp := xmpp.NewIQ(xmpp.Attrs{Type: "result", From: iq.To, To: iq.From, Id: iq.Id, Lang: "en"})
 	var payload xmpp.Version
 	payload.Name = "Fluux XMPP Component"
 	payload.Version = "0.0.1"

_examples/xmpp_echo/xmpp_echo.go

@@ -43,7 +43,7 @@ func handleMessage(s xmpp.Sender, p xmpp.Packet) {
 	}
 
 	_, _ = fmt.Fprintf(os.Stdout, "Body = %s - from = %s\n", msg.Body, msg.From)
-	reply := xmpp.Message{PacketAttrs: xmpp.PacketAttrs{To: msg.From}, Body: msg.Body}
+	reply := xmpp.Message{Attrs: xmpp.Attrs{To: msg.From}, Body: msg.Body}
 	_ = s.Send(reply)
 }
 

_examples/xmpp_jukebox/xmpp_jukebox.go

@@ -34,6 +34,7 @@ func main() {
 		Address:  *address,
 		Jid:      *jid,
 		Password: *password,
+		// PacketLogger: os.Stdout,
 		Insecure: true,
 	}
 
@@ -91,7 +92,7 @@ func handleIQ(s xmpp.Sender, p xmpp.Packet, player *mpg123.Player) {
 		playSCURL(player, url)
 		setResponse := new(xmpp.ControlSetResponse)
 		// FIXME: Broken
-		reply := xmpp.IQ{PacketAttrs: xmpp.PacketAttrs{To: iq.From, Type: "result", Id: iq.Id}, Payload: setResponse}
+		reply := xmpp.IQ{Attrs: xmpp.Attrs{To: iq.From, Type: "result", Id: iq.Id}, Payload: setResponse}
 		_ = s.Send(reply)
 		// TODO add Soundclound artist / title retrieval
 		sendUserTune(s, "Radiohead", "Spectre")
@@ -102,7 +103,7 @@ func handleIQ(s xmpp.Sender, p xmpp.Packet, player *mpg123.Player) {
 
 func sendUserTune(s xmpp.Sender, artist string, title string) {
 	tune := xmpp.Tune{Artist: artist, Title: title}
-	iq := xmpp.NewIQ("set", "", "", "usertune-1", "en")
+	iq := xmpp.NewIQ(xmpp.Attrs{Type: "set", Id: "usertune-1", Lang: "en"})
 	payload := xmpp.PubSub{Publish: &xmpp.Publish{Node: "http://jabber.org/protocol/tune", Item: xmpp.Item{Tune: &tune}}}
 	iq.Payload = &payload
 	_ = s.Send(iq)

auth.go

@@ -33,7 +33,7 @@ func authPlain(socket io.ReadWriter, decoder *xml.Decoder, user string, password
 	fmt.Fprintf(socket, "<auth xmlns='%s' mechanism='PLAIN'>%s</auth>", nsSASL, enc)
 
 	// Next message should be either success or failure.
-	val, err := next(decoder)
+	val, err := nextPacket(decoder)
 	if err != nil {
 		return err
 	}

backoff.go

@@ -13,7 +13,7 @@ It can be used in several ways:
 - Using ticker channel to trigger callback function on tick
 
 The functions for Backoff are not threadsafe, but you can:
-- Keep the attempt counter on your end and use DurationForAttempt(int)
+- Keep the attempt counter on your end and use durationForAttempt(int)
 - Use lock in your own code to protect the Backoff structure.
 
 TODO: Implement Backoff Ticker channel
@@ -34,11 +34,11 @@ const (
 	defaultCap    int = 180000 // 3 minutes
 )
 
-// Backoff can provide increasing duration with the number of attempt
+// backoff provides increasing duration with the number of attempt
 // performed. The structure is used to support exponential backoff on
 // connection attempts to avoid hammering the server we are connecting
 // to.
-type Backoff struct {
+type backoff struct {
 	NoJitter     bool
 	Base         int
 	Factor       int
@@ -47,20 +47,20 @@ type Backoff struct {
 	attempt      int
 }
 
-// Duration returns the duration to apply to the current attempt.
-func (b *Backoff) Duration() time.Duration {
-	d := b.DurationForAttempt(b.attempt)
+// duration returns the duration to apply to the current attempt.
+func (b *backoff) duration() time.Duration {
+	d := b.durationForAttempt(b.attempt)
 	b.attempt++
 	return d
 }
 
-// Wait sleeps for backoff duration for current attempt.
-func (b *Backoff) Wait() {
-	time.Sleep(b.Duration())
+// wait sleeps for backoff duration for current attempt.
+func (b *backoff) wait() {
+	time.Sleep(b.duration())
 }
 
-// DurationForAttempt returns a duration for an attempt number, in a stateless way.
-func (b *Backoff) DurationForAttempt(attempt int) time.Duration {
+// durationForAttempt returns a duration for an attempt number, in a stateless way.
+func (b *backoff) durationForAttempt(attempt int) time.Duration {
 	b.setDefault()
 	expBackoff := math.Min(float64(b.Cap), float64(b.Base)*math.Pow(float64(b.Factor), float64(b.attempt)))
 	d := int(math.Trunc(expBackoff))
@@ -70,13 +70,13 @@ func (b *Backoff) DurationForAttempt(attempt int) time.Duration {
 	return time.Duration(d) * time.Millisecond
 }
 
-// Reset sets back the number of attempts to 0. This is to be called after a successfull operation has been performed,
+// reset sets back the number of attempts to 0. This is to be called after a successful operation has been performed,
 // to reset the exponential backoff interval.
-func (b *Backoff) Reset() {
+func (b *backoff) reset() {
 	b.attempt = 0
 }
 
-func (b *Backoff) setDefault() {
+func (b *backoff) setDefault() {
 	if b.Base == 0 {
 		b.Base = defaultBase
 	}

backoff_test.go

@@ -1,21 +1,19 @@
-package xmpp_test
+package xmpp
 
 import (
 	"testing"
 	"time"
-
-	"gosrc.io/xmpp"
 )
 
 func TestDurationForAttempt_NoJitter(t *testing.T) {
-	b := xmpp.Backoff{Base: 25, NoJitter: true}
+	b := backoff{Base: 25, NoJitter: true}
 	bInMS := time.Duration(b.Base) * time.Millisecond
-	if b.DurationForAttempt(0) != bInMS {
-		t.Errorf("incorrect default duration for attempt #0 (%d) = %d", b.DurationForAttempt(0)/time.Millisecond, bInMS/time.Millisecond)
+	if b.durationForAttempt(0) != bInMS {
+		t.Errorf("incorrect default duration for attempt #0 (%d) = %d", b.durationForAttempt(0)/time.Millisecond, bInMS/time.Millisecond)
 	}
 	var prevDuration, d time.Duration
 	for i := 0; i < 10; i++ {
-		d = b.DurationForAttempt(i)
+		d = b.durationForAttempt(i)
 		if !(d >= prevDuration) {
 			t.Errorf("duration should be increasing between attempts. #%d (%d) > %d", i, d, prevDuration)
 		}

check_cert.go

@@ -54,14 +54,14 @@ func (c *ServerCheck) Check() error {
 	}
 
 	// Set xml decoder and extract streamID from reply (not used for now)
-	_, err = initDecoder(decoder)
+	_, err = initStream(decoder)
 	if err != nil {
 		return err
 	}
 
 	// extract stream features
 	var f StreamFeatures
-	packet, err := next(decoder)
+	packet, err := nextPacket(decoder)
 	if err != nil {
 		err = fmt.Errorf("stream open decode features: %s", err)
 		return err

client.go

@@ -200,7 +200,7 @@ func (c *Client) SendRaw(packet string) error {
 // Loop: Receive data from server
 func (c *Client) recv(keepaliveQuit chan<- struct{}) (err error) {
 	for {
-		val, err := next(c.Session.decoder)
+		val, err := nextPacket(c.Session.decoder)
 		if err != nil {
 			close(keepaliveQuit)
 			c.updateState(StateDisconnected)

component.go

@@ -78,7 +78,7 @@ func (c *Component) Connect() error {
 	c.decoder = xml.NewDecoder(conn)
 
 	// 2. Initialize xml decoder and extract streamID from reply
-	streamId, err := initDecoder(c.decoder)
+	streamId, err := initStream(c.decoder)
 	if err != nil {
 		return errors.New("cannot init decoder " + err.Error())
 	}
@@ -89,7 +89,7 @@ func (c *Component) Connect() error {
 	}
 
 	// 4. Check server response for authentication
-	val, err := next(c.decoder)
+	val, err := nextPacket(c.decoder)
 	if err != nil {
 		return err
 	}
@@ -119,7 +119,7 @@ func (c *Component) SetHandler(handler EventHandler) {
 // Receiver Go routine receiver
 func (c *Component) recv() (err error) {
 	for {
-		val, err := next(c.decoder)
+		val, err := nextPacket(c.decoder)
 		if err != nil {
 			c.updateState(StateDisconnected)
 			return err

doc.go

@@ -1,13 +1,23 @@
 /*
-Fluux XMPP is a Go XMPP library, focusing on simplicity, simple automation, and IoT.
+Fluux XMPP is an modern and full-featured XMPP library that can be used to build clients or
+server components.
 
-The goal is to make simple to write simple adhoc XMPP clients:
+The goal is to make simple to write modern compliant XMPP software:
 
  - For automation (like for example monitoring of an XMPP service),
  - For building connected "things" by plugging them on an XMPP server,
  - For writing simple chatbots to control a service or a thing.
+ - For writing XMPP servers components. Fluux XMPP supports:
+    - XEP-0114: Jabber Component Protocol
+    - XEP-0355: Namespace Delegation
+    - XEP-0356: Privileged Entity
 
-Fluux XMPP can be used to build XMPP clients or XMPP components.
+The library is designed to have minimal dependencies. For now, the library does not depend on any other library.
+
+The library includes a StreamManager that provides features like autoreconnect exponential back-off.
+
+The library is implementing latest versions of the XMPP specifications (RFC 6120 and RFC 6121), and includes
+support for many extensions.
 
 Clients
 

error.go

@@ -0,0 +1,118 @@
+package xmpp
+
+import (
+	"encoding/xml"
+	"strconv"
+)
+
+/*
+TODO support ability to put Raw payload inside IQ
+*/
+
+// ============================================================================
+// XMPP Errors
+
+// Err is an XMPP stanza payload that is used to report error on message,
+// presence or iq stanza.
+// It is intended to be added in the payload of the erroneous stanza.
+type Err struct {
+	XMLName xml.Name  `xml:"error"`
+	Code    int       `xml:"code,attr,omitempty"`
+	Type    ErrorType `xml:"type,attr"` // required
+	Reason  string
+	Text    string `xml:"urn:ietf:params:xml:ns:xmpp-stanzas text,omitempty"`
+}
+
+func (x *Err) Namespace() string {
+	return x.XMLName.Space
+}
+
+// UnmarshalXML implements custom parsing for IQs
+func (x *Err) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	x.XMLName = start.Name
+
+	// Extract attributes
+	for _, attr := range start.Attr {
+		if attr.Name.Local == "type" {
+			x.Type = ErrorType(attr.Value)
+		}
+		if attr.Name.Local == "code" {
+			if code, err := strconv.Atoi(attr.Value); err == nil {
+				x.Code = code
+			}
+		}
+	}
+
+	// Check subelements to extract error text and reason (from local namespace).
+	for {
+		t, err := d.Token()
+		if err != nil {
+			return err
+		}
+
+		switch tt := t.(type) {
+
+		case xml.StartElement:
+			elt := new(Node)
+
+			err = d.DecodeElement(elt, &tt)
+			if err != nil {
+				return err
+			}
+
+			textName := xml.Name{Space: "urn:ietf:params:xml:ns:xmpp-stanzas", Local: "text"}
+			if elt.XMLName == textName {
+				x.Text = string(elt.Content)
+			} else if elt.XMLName.Space == "urn:ietf:params:xml:ns:xmpp-stanzas" {
+				x.Reason = elt.XMLName.Local
+			}
+
+		case xml.EndElement:
+			if tt == start.End() {
+				return nil
+			}
+		}
+	}
+}
+
+func (x Err) MarshalXML(e *xml.Encoder, start xml.StartElement) (err error) {
+	if x.Code == 0 {
+		return nil
+	}
+
+	// Encode start element and attributes
+	start.Name = xml.Name{Local: "error"}
+
+	code := xml.Attr{
+		Name:  xml.Name{Local: "code"},
+		Value: strconv.Itoa(x.Code),
+	}
+	start.Attr = append(start.Attr, code)
+
+	if len(x.Type) > 0 {
+		typ := xml.Attr{
+			Name:  xml.Name{Local: "type"},
+			Value: string(x.Type),
+		}
+		start.Attr = append(start.Attr, typ)
+	}
+	err = e.EncodeToken(start)
+
+	// SubTags
+	// Reason
+	if x.Reason != "" {
+		reason := xml.Name{Space: "urn:ietf:params:xml:ns:xmpp-stanzas", Local: x.Reason}
+		e.EncodeToken(xml.StartElement{Name: reason})
+		e.EncodeToken(xml.EndElement{Name: reason})
+	}
+
+	// Text
+	if x.Text != "" {
+		text := xml.Name{Space: "urn:ietf:params:xml:ns:xmpp-stanzas", Local: "text"}
+		e.EncodeToken(xml.StartElement{Name: text})
+		e.EncodeToken(xml.CharData(x.Text))
+		e.EncodeToken(xml.EndElement{Name: text})
+	}
+
+	return e.EncodeToken(xml.EndElement{Name: start.Name})
+}

error_enum.go

@@ -0,0 +1,13 @@
+package xmpp
+
+// ErrorType is a Enum of error attribute type
+type ErrorType string
+
+// RFC 6120: part of A.5 Client Namespace and A.6 Server Namespace
+const (
+	ErrorTypeAuth     ErrorType = "auth"
+	ErrorTypeCancel   ErrorType = "cancel"
+	ErrorTypeContinue ErrorType = "continue"
+	ErrorTypeModify   ErrorType = "motify"
+	ErrorTypeWait     ErrorType = "wait"
+)

iq.go

@@ -3,127 +3,20 @@ package xmpp
 import (
 	"encoding/xml"
 	"fmt"
-	"strconv"
 )
 
 /*
 TODO support ability to put Raw payload inside IQ
 */
 
-// ============================================================================
-// XMPP Errors
-
-// Err is an XMPP stanza payload that is used to report error on message,
-// presence or iq stanza.
-// It is intended to be added in the payload of the erroneous stanza.
-type Err struct {
-	XMLName xml.Name `xml:"error"`
-	Code    int      `xml:"code,attr,omitempty"`
-	Type    string   `xml:"type,attr,omitempty"`
-	Reason  string
-	Text    string `xml:"urn:ietf:params:xml:ns:xmpp-stanzas text,omitempty"`
-}
-
-func (x *Err) Namespace() string {
-	return x.XMLName.Space
-}
-
-// UnmarshalXML implements custom parsing for IQs
-func (x *Err) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
-	x.XMLName = start.Name
-
-	// Extract attributes
-	for _, attr := range start.Attr {
-		if attr.Name.Local == "type" {
-			x.Type = attr.Value
-		}
-		if attr.Name.Local == "code" {
-			if code, err := strconv.Atoi(attr.Value); err == nil {
-				x.Code = code
-			}
-		}
-	}
-
-	// Check subelements to extract error text and reason (from local namespace).
-	for {
-		t, err := d.Token()
-		if err != nil {
-			return err
-		}
-
-		switch tt := t.(type) {
-
-		case xml.StartElement:
-			elt := new(Node)
-
-			err = d.DecodeElement(elt, &tt)
-			if err != nil {
-				return err
-			}
-
-			textName := xml.Name{Space: "urn:ietf:params:xml:ns:xmpp-stanzas", Local: "text"}
-			if elt.XMLName == textName {
-				x.Text = string(elt.Content)
-			} else if elt.XMLName.Space == "urn:ietf:params:xml:ns:xmpp-stanzas" {
-				x.Reason = elt.XMLName.Local
-			}
-
-		case xml.EndElement:
-			if tt == start.End() {
-				return nil
-			}
-		}
-	}
-}
-
-func (x Err) MarshalXML(e *xml.Encoder, start xml.StartElement) (err error) {
-	if x.Code == 0 {
-		return nil
-	}
-
-	// Encode start element and attributes
-	start.Name = xml.Name{Local: "error"}
-
-	code := xml.Attr{
-		Name:  xml.Name{Local: "code"},
-		Value: strconv.Itoa(x.Code),
-	}
-	start.Attr = append(start.Attr, code)
-
-	if len(x.Type) > 0 {
-		typ := xml.Attr{
-			Name:  xml.Name{Local: "type"},
-			Value: x.Type,
-		}
-		start.Attr = append(start.Attr, typ)
-	}
-	err = e.EncodeToken(start)
-
-	// SubTags
-	// Reason
-	if x.Reason != "" {
-		reason := xml.Name{Space: "urn:ietf:params:xml:ns:xmpp-stanzas", Local: x.Reason}
-		e.EncodeToken(xml.StartElement{Name: reason})
-		e.EncodeToken(xml.EndElement{Name: reason})
-	}
-
-	// Text
-	if x.Text != "" {
-		text := xml.Name{Space: "urn:ietf:params:xml:ns:xmpp-stanzas", Local: "text"}
-		e.EncodeToken(xml.StartElement{Name: text})
-		e.EncodeToken(xml.CharData(x.Text))
-		e.EncodeToken(xml.EndElement{Name: text})
-	}
-
-	return e.EncodeToken(xml.EndElement{Name: start.Name})
-}
-
 // ============================================================================
 // IQ Packet
 
+// IQ implements RFC 6120 - A.5 Client Namespace (a part)
 type IQ struct { // Info/Query
 	XMLName xml.Name `xml:"iq"`
-	PacketAttrs
+	// MUST have a ID
+	Attrs
 	// We can only have one payload on IQ:
 	//   "An IQ stanza of type "get" or "set" MUST contain exactly one
 	//    child element, which specifies the semantics of the particular
@@ -133,16 +26,16 @@ type IQ struct { // Info/Query
 	RawXML  string    `xml:",innerxml"`
 }
 
-func NewIQ(iqtype, from, to, id, lang string) IQ {
+type IQPayload interface {
+	Namespace() string
+}
+
+func NewIQ(a Attrs) IQ {
+	// TODO generate IQ ID if not set
+	// TODO ensure that type is set, as it is required
 	return IQ{
 		XMLName: xml.Name{Local: "iq"},
-		PacketAttrs: PacketAttrs{
-			Id:   id,
-			From: from,
-			To:   to,
-			Type: iqtype,
-			Lang: lang,
-		},
+		Attrs:   a,
 	}
 }
 
@@ -182,7 +75,7 @@ func (iq *IQ) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 			iq.Id = attr.Value
 		}
 		if attr.Name.Local == "type" {
-			iq.Type = attr.Value
+			iq.Type = StanzaType(attr.Value)
 		}
 		if attr.Name.Local == "to" {
 			iq.To = attr.Value
@@ -190,9 +83,6 @@ func (iq *IQ) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 		if attr.Name.Local == "from" {
 			iq.From = attr.Value
 		}
-		if attr.Name.Local == "lang" {
-			iq.Lang = attr.Value
-		}
 	}
 
 	// decode inner elements
@@ -223,6 +113,7 @@ func (iq *IQ) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 				iq.Payload = iqExt
 				continue
 			}
+			// TODO: If unknown decode as generic node
 			return fmt.Errorf("unexpected element in iq: %s %s", tt.Name.Space, tt.Name.Local)
 		case xml.EndElement:
 			if tt == start.End() {
@@ -233,11 +124,7 @@ func (iq *IQ) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 }
 
 // ============================================================================
-// Generic IQ Payload
-
-type IQPayload interface {
-	Namespace() string
-}
+// Generic / unknown content
 
 // Node is a generic structure to represent XML data. It is used to parse
 // unreferenced or custom stanza payload.

iq_test.go

@@ -16,7 +16,7 @@ func TestUnmarshalIqs(t *testing.T) {
 		parsedIQ xmpp.IQ
 	}{
 		{"<iq id=\"1\" type=\"set\" to=\"test@localhost\"/>",
-			xmpp.IQ{XMLName: xml.Name{Space: "", Local: "iq"}, PacketAttrs: xmpp.PacketAttrs{To: "test@localhost", Type: "set", Id: "1"}}},
+			xmpp.IQ{XMLName: xml.Name{Local: "iq"}, Attrs: xmpp.Attrs{Type: xmpp.IQTypeSet, To: "test@localhost", Id: "1"}}},
 		//{"<iq xmlns=\"jabber:client\" id=\"2\" type=\"set\" to=\"test@localhost\" from=\"server\"><set xmlns=\"urn:xmpp:iot:control\"/></iq>", IQ{XMLName: xml.Name{Space: "jabber:client", Local: "iq"}, PacketAttrs: PacketAttrs{To: "test@localhost", From: "server", Type: "set", Id: "2"}, Payload: cs1}},
 	}
 
@@ -35,7 +35,7 @@ func TestUnmarshalIqs(t *testing.T) {
 }
 
 func TestGenerateIq(t *testing.T) {
-	iq := xmpp.NewIQ("result", "admin@localhost", "test@localhost", "1", "en")
+	iq := xmpp.NewIQ(xmpp.Attrs{Type: xmpp.IQTypeResult, From: "admin@localhost", To: "test@localhost", Id: "1"})
 	payload := xmpp.DiscoInfo{
 		Identity: xmpp.Identity{
 			Name:     "Test Gateway",
@@ -93,7 +93,7 @@ func TestErrorTag(t *testing.T) {
 }
 
 func TestDiscoItems(t *testing.T) {
-	iq := xmpp.NewIQ("get", "romeo@montague.net/orchard", "catalog.shakespeare.lit", "items3", "en")
+	iq := xmpp.NewIQ(xmpp.Attrs{Type: xmpp.IQTypeGet, From: "romeo@montague.net/orchard", To: "catalog.shakespeare.lit", Id: "items3"})
 	payload := xmpp.DiscoItems{
 		Node: "music",
 	}

message.go

@@ -7,9 +7,11 @@ import (
 // ============================================================================
 // Message Packet
 
+// Message implements RFC 6120 - A.5 Client Namespace (a part)
 type Message struct {
 	XMLName xml.Name `xml:"message"`
-	PacketAttrs
+	Attrs
+
 	Subject    string         `xml:"subject,omitempty"`
 	Body       string         `xml:"body,omitempty"`
 	Thread     string         `xml:"thread,omitempty"`
@@ -21,16 +23,10 @@ func (Message) Name() string {
 	return "message"
 }
 
-func NewMessage(msgtype, from, to, id, lang string) Message {
+func NewMessage(a Attrs) Message {
 	return Message{
 		XMLName: xml.Name{Local: "message"},
-		PacketAttrs: PacketAttrs{
-			Id:   id,
-			From: from,
-			To:   to,
-			Type: msgtype,
-			Lang: lang,
-		},
+		Attrs:   a,
 	}
 }
 
@@ -63,7 +59,7 @@ func (msg *Message) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 			msg.Id = attr.Value
 		}
 		if attr.Name.Local == "type" {
-			msg.Type = attr.Value
+			msg.Type = StanzaType(attr.Value)
 		}
 		if attr.Name.Local == "to" {
 			msg.To = attr.Value

message_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func TestGenerateMessage(t *testing.T) {
-	message := xmpp.NewMessage("chat", "admin@localhost", "test@localhost", "1", "en")
+	message := xmpp.NewMessage(xmpp.Attrs{Type: xmpp.MessageTypeChat, From: "admin@localhost", To: "test@localhost", Id: "1"})
 	message.Body = "Hi"
 	message.Subject = "Msg Subject"
 

packet.go

@@ -4,13 +4,13 @@ type Packet interface {
 	Name() string
 }
 
-// PacketAttrs represents the common structure for base XMPP packets.
-type PacketAttrs struct {
-	Id   string `xml:"id,attr,omitempty"`
-	From string `xml:"from,attr,omitempty"`
-	To   string `xml:"to,attr,omitempty"`
-	Type string `xml:"type,attr,omitempty"`
-	Lang string `xml:"lang,attr,omitempty"`
+// Attrs represents the common structure for base XMPP packets.
+type Attrs struct {
+	Type StanzaType `xml:"type,attr,omitempty"`
+	Id   string     `xml:"id,attr,omitempty"`
+	From string     `xml:"from,attr,omitempty"`
+	To   string     `xml:"to,attr,omitempty"`
+	Lang string     `xml:"lang,attr,omitempty"`
 }
 
 type packetFormatter interface {

packet_enum.go

@@ -0,0 +1,25 @@
+package xmpp
+
+type StanzaType string
+
+// RFC 6120: part of A.5 Client Namespace and A.6 Server Namespace
+const (
+	IQTypeError  StanzaType = "error"
+	IQTypeGet    StanzaType = "get"
+	IQTypeResult StanzaType = "result"
+	IQTypeSet    StanzaType = "set"
+
+	MessageTypeChat      StanzaType = "chat"
+	MessageTypeError     StanzaType = "error"
+	MessageTypeGroupchat StanzaType = "groupchat"
+	MessageTypeHeadline  StanzaType = "headline"
+	MessageTypeNormal    StanzaType = "normal" // Default
+
+	PresenceTypeError        StanzaType = "error"
+	PresenceTypeProbe        StanzaType = "probe"
+	PresenceTypeSubscribe    StanzaType = "subscribe"
+	PresenceTypeSubscribed   StanzaType = "subscribed"
+	PresenceTypeUnavailable  StanzaType = "unavailable"
+	PresenceTypeUnsubscribe  StanzaType = "unsubscribe"
+	PresenceTypeUnsubscribed StanzaType = "unsubscribed"
+)

parser.go

@@ -14,29 +14,29 @@ import (
 //       reattach features (allowing to resume an existing stream at the point the connection was interrupted, without
 //       getting through the authentication process.
 // TODO We should handle stream error from XEP-0114 ( <conflict/> or <host-unknown/> )
-func initDecoder(p *xml.Decoder) (sessionID string, err error) {
+func initStream(p *xml.Decoder) (sessionID string, err error) {
 	for {
 		var t xml.Token
 		t, err = p.Token()
 		if err != nil {
-			return
+			return sessionID, err
 		}
 
 		switch elem := t.(type) {
 		case xml.StartElement:
 			if elem.Name.Space != NSStream || elem.Name.Local != "stream" {
 				err = errors.New("xmpp: expected <stream> but got <" + elem.Name.Local + "> in " + elem.Name.Space)
-				return
+				return sessionID, err
 			}
 
-			// Parse Stream attributes
+			// Parse XMPP stream attributes
 			for _, attrs := range elem.Attr {
 				switch attrs.Name.Local {
 				case "id":
 					sessionID = attrs.Value
 				}
 			}
-			return
+			return sessionID, err
 		}
 	}
 }
@@ -58,10 +58,12 @@ func nextStart(p *xml.Decoder) (xml.StartElement, error) {
 	}
 }
 
-// next scans XML token stream for next element and then assign a structure to decode
-// that elements.
+// nextPacket scans XML token stream for next complete XMPP stanza.
+// Once the type of stanza has been identified, a structure is created to decode
+// that stanza and returned.
 // TODO Use an interface to return packets interface xmppDecoder
-func next(p *xml.Decoder) (Packet, error) {
+// TODO make auth and bind use nextPacket instead of directly nextStart
+func nextPacket(p *xml.Decoder) (Packet, error) {
 	// Read start element to find out how we want to parse the XMPP packet
 	se, err := nextStart(p)
 	if err != nil {
@@ -84,6 +86,13 @@ func next(p *xml.Decoder) (Packet, error) {
 	}
 }
 
+/*
+TODO: From all the decoder, we can return a pointer to the actual concrete type, instead of directly that
+   type.
+   That way, we have a consistent way to do type assertion, always matching against pointers.
+*/
+
+// decodeStream will fully decode a stream packet
 func decodeStream(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	switch se.Name.Local {
 	case "error":
@@ -96,6 +105,7 @@ func decodeStream(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	}
 }
 
+// decodeSASL decodes a packet related to SASL authentication.
 func decodeSASL(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	switch se.Name.Local {
 	case "success":
@@ -108,6 +118,7 @@ func decodeSASL(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	}
 }
 
+// decodeClient decodes all known packets in the client namespace.
 func decodeClient(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	switch se.Name.Local {
 	case "message":
@@ -122,9 +133,10 @@ func decodeClient(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	}
 }
 
+// decodeClient decodes all known packets in the component namespace.
 func decodeComponent(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	switch se.Name.Local {
-	case "handshake":
+	case "handshake": // handshake is used to authenticate components
 		return handshake.decode(p, se)
 	case "message":
 		return message.decode(p, se)

presence.go

@@ -5,28 +5,24 @@ import "encoding/xml"
 // ============================================================================
 // Presence Packet
 
+// Presence implements RFC 6120 - A.5 Client Namespace (a part)
 type Presence struct {
 	XMLName xml.Name `xml:"presence"`
-	PacketAttrs
-	Show     string `xml:"show,omitempty"` // away, chat, dnd, xa
-	Status   string `xml:"status,omitempty"`
-	Priority int    `xml:"priority,omitempty"`
-	Error    Err    `xml:"error,omitempty"`
+	Attrs
+	Show     PresenceShow `xml:"show,omitempty"`
+	Status   string       `xml:"status,omitempty"`
+	Priority int8         `xml:"priority,omitempty"` // default: 0
+	Error    Err          `xml:"error,omitempty"`
 }
 
 func (Presence) Name() string {
 	return "presence"
 }
 
-func NewPresence(from, to, id, lang string) Presence {
+func NewPresence(a Attrs) Presence {
 	return Presence{
 		XMLName: xml.Name{Local: "presence"},
-		PacketAttrs: PacketAttrs{
-			Id:   id,
-			From: from,
-			To:   to,
-			Lang: lang,
-		},
+		Attrs:   a,
 	}
 }
 

presence_enum.go

@@ -0,0 +1,12 @@
+package xmpp
+
+// PresenceShow is a Enum of presence element show
+type PresenceShow string
+
+// RFC 6120: part of A.5 Client Namespace and A.6 Server Namespace
+const (
+	PresenceShowAway PresenceShow = "away"
+	PresenceShowChat PresenceShow = "chat"
+	PresenceShowDND  PresenceShow = "dnd"
+	PresenceShowXA   PresenceShow = "xa"
+)

presence_test.go

@@ -10,8 +10,8 @@ import (
 )
 
 func TestGeneratePresence(t *testing.T) {
-	presence := xmpp.NewPresence("admin@localhost", "test@localhost", "1", "en")
-	presence.Show = "chat"
+	presence := xmpp.NewPresence(xmpp.Attrs{From: "admin@localhost", To: "test@localhost", Id: "1"})
+	presence.Show = xmpp.PresenceShowChat
 
 	data, err := xml.Marshal(presence)
 	if err != nil {
@@ -32,13 +32,13 @@ func TestPresenceSubElt(t *testing.T) {
 	// Test structure to ensure that show, status and priority are correctly defined as presence
 	// package sub-elements
 	type pres struct {
-		Show     string `xml:"show"`
-		Status   string `xml:"status"`
-		Priority int    `xml:"priority"`
+		Show     xmpp.PresenceShow `xml:"show"`
+		Status   string            `xml:"status"`
+		Priority int8              `xml:"priority"`
 	}
 
-	presence := xmpp.NewPresence("admin@localhost", "test@localhost", "1", "en")
-	presence.Show = "xa"
+	presence := xmpp.NewPresence(xmpp.Attrs{From: "admin@localhost", To: "test@localhost", Id: "1"})
+	presence.Show = xmpp.PresenceShowXA
 	presence.Status = "Coding"
 	presence.Priority = 10
 

router_test.go

@@ -19,8 +19,7 @@ func TestNameMatcher(t *testing.T) {
 
 	// Check that a message packet is properly matched
 	conn := NewSenderMock()
-	// TODO: We want packet creation code to use struct to use default values
-	msg := xmpp.NewMessage("chat", "", "test@localhost", "1", "")
+	msg := xmpp.NewMessage(xmpp.Attrs{Type: xmpp.MessageTypeChat, To: "test@localhost", Id: "1"})
 	msg.Body = "Hello"
 	router.Route(conn, msg)
 	if conn.String() != successFlag {
@@ -29,7 +28,7 @@ func TestNameMatcher(t *testing.T) {
 
 	// Check that an IQ packet is not matched
 	conn = NewSenderMock()
-	iq := xmpp.NewIQ("get", "", "localhost", "1", "")
+	iq := xmpp.NewIQ(xmpp.Attrs{Type: xmpp.IQTypeGet, To: "localhost", Id: "1"})
 	iq.Payload = &xmpp.DiscoInfo{}
 	router.Route(conn, iq)
 	if conn.String() == successFlag {
@@ -47,7 +46,8 @@ func TestIQNSMatcher(t *testing.T) {
 
 	// Check that an IQ with proper namespace does match
 	conn := NewSenderMock()
-	iqDisco := xmpp.NewIQ("get", "", "localhost", "1", "")
+	iqDisco := xmpp.NewIQ(xmpp.Attrs{Type: xmpp.IQTypeGet, To: "localhost", Id: "1"})
+	// TODO: Add a function to generate payload with proper namespace initialisation
 	iqDisco.Payload = &xmpp.DiscoInfo{
 		XMLName: xml.Name{
 			Space: xmpp.NSDiscoInfo,
@@ -60,7 +60,8 @@ func TestIQNSMatcher(t *testing.T) {
 
 	// Check that another namespace is not matched
 	conn = NewSenderMock()
-	iqVersion := xmpp.NewIQ("get", "", "localhost", "1", "")
+	iqVersion := xmpp.NewIQ(xmpp.Attrs{Type: xmpp.IQTypeGet, To: "localhost", Id: "1"})
+	// TODO: Add a function to generate payload with proper namespace initialisation
 	iqVersion.Payload = &xmpp.DiscoInfo{
 		XMLName: xml.Name{
 			Space: "jabber:iq:version",
@@ -240,7 +241,7 @@ func (s SenderMock) String() string {
 
 func TestSenderMock(t *testing.T) {
 	conn := NewSenderMock()
-	msg := xmpp.NewMessage("", "", "test@localhost", "1", "")
+	msg := xmpp.NewMessage(xmpp.Attrs{To: "test@localhost", Id: "1"})
 	msg.Body = "Hello"
 	if err := conn.Send(msg); err != nil {
 		t.Error("Could not send message")

session.go

@@ -92,7 +92,7 @@ func (s *Session) open(domain string) (f StreamFeatures) {
 	}
 
 	// Set xml decoder and extract streamID from reply
-	s.StreamId, s.err = initDecoder(s.decoder) // TODO refactor / rename
+	s.StreamId, s.err = initStream(s.decoder) // TODO refactor / rename
 	if s.err != nil {
 		return
 	}

stream_manager.go

@@ -104,7 +104,7 @@ func (sm *StreamManager) Stop() {
 
 // connect manages the reconnection loop and apply the define backoff to avoid overloading the server.
 func (sm *StreamManager) connect() error {
-	var backoff Backoff // TODO: Group backoff calculation features with connection manager?
+	var backoff backoff // TODO: Group backoff calculation features with connection manager?
 
 	for {
 		var err error
@@ -118,7 +118,7 @@ func (sm *StreamManager) connect() error {
 					return xerrors.Errorf("unrecoverable connect error %w", actualErr)
 				}
 			}
-			backoff.Wait()
+			backoff.wait()
 		} else { // We are connected, we can leave the retry loop
 			break
 		}