Add initial support for stream management

For now it support enabling SM, replying to ack requests from server,
and trying resuming the session with existing Stream Management state.

stanza/parser.go

@@ -63,6 +63,8 @@ func NextPacket(p *xml.Decoder) (Packet, error) {
 		return decodeClient(p, se)
 	case NSComponent:
 		return decodeComponent(p, se)
+	case NSStreamManagement:
+		return sm.decode(p, se)
 	default:
 		return nil, errors.New("unknown namespace " +
 			se.Name.Space + " <" + se.Name.Local + "/>")
@@ -133,7 +135,7 @@ func decodeClient(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	}
 }
 
-// decodeClient decodes all known packets in the component namespace.
+// decodeComponent decodes all known packets in the component namespace.
 func decodeComponent(p *xml.Decoder, se xml.StartElement) (Packet, error) {
 	switch se.Name.Local {
 	case "handshake": // handshake is used to authenticate components

stanza/stream_management.go

@@ -0,0 +1,121 @@
+package stanza
+
+import (
+	"encoding/xml"
+	"errors"
+)
+
+const (
+	NSStreamManagement = "urn:xmpp:sm:3"
+)
+
+// Enabled as defined in Stream Management spec
+// Reference: https://xmpp.org/extensions/xep-0198.html#enable
+type SMEnabled struct {
+	XMLName  xml.Name `xml:"urn:xmpp:sm:3 enabled"`
+	Id       string   `xml:"id,attr,omitempty"`
+	Location string   `xml:"location,attr,omitempty"`
+	Resume   string   `xml:"resume,attr,omitempty"`
+	Max      uint     `xml:"max,attr,omitempty"`
+}
+
+func (SMEnabled) Name() string {
+	return "Stream Management: enabled"
+}
+
+// Request as defined in Stream Management spec
+// Reference: https://xmpp.org/extensions/xep-0198.html#acking
+type SMRequest struct {
+	XMLName xml.Name `xml:"urn:xmpp:sm:3 r"`
+}
+
+func (SMRequest) Name() string {
+	return "Stream Management: request"
+}
+
+// Answer as defined in Stream Management spec
+// Reference: https://xmpp.org/extensions/xep-0198.html#acking
+type SMAnswer struct {
+	XMLName xml.Name `xml:"urn:xmpp:sm:3 a"`
+	H       uint     `xml:"h,attr,omitempty"`
+}
+
+func (SMAnswer) Name() string {
+	return "Stream Management: answer"
+}
+
+// Resumed as defined in Stream Management spec
+// Reference: https://xmpp.org/extensions/xep-0198.html#acking
+type SMResumed struct {
+	XMLName xml.Name `xml:"urn:xmpp:sm:3 resumed"`
+	PrevId  string   `xml:"previd,attr,omitempty"`
+	H       uint     `xml:"h,attr,omitempty"`
+}
+
+func (SMResumed) Name() string {
+	return "Stream Management: resumed"
+}
+
+// Failed as defined in Stream Management spec
+// Reference: https://xmpp.org/extensions/xep-0198.html#acking
+type SMFailed struct {
+	XMLName xml.Name `xml:"urn:xmpp:sm:3 failed"`
+	// TODO: Handle decoding error cause (need custom parsing).
+}
+
+func (SMFailed) Name() string {
+	return "Stream Management: failed"
+}
+
+type smDecoder struct{}
+
+var sm smDecoder
+
+// decode decodes all known nonza in the stream management namespace.
+func (s smDecoder) decode(p *xml.Decoder, se xml.StartElement) (Packet, error) {
+	switch se.Name.Local {
+	case "enabled":
+		return s.decodeEnabled(p, se)
+	case "resumed":
+		return s.decodeResumed(p, se)
+	case "r":
+		return s.decodeRequest(p, se)
+	case "h":
+		return s.decodeAnswer(p, se)
+	case "failed":
+		return s.decodeFailed(p, se)
+	default:
+		return nil, errors.New("unexpected XMPP packet " +
+			se.Name.Space + " <" + se.Name.Local + "/>")
+	}
+}
+
+func (smDecoder) decodeEnabled(p *xml.Decoder, se xml.StartElement) (SMEnabled, error) {
+	var packet SMEnabled
+	err := p.DecodeElement(&packet, &se)
+	return packet, err
+}
+
+func (smDecoder) decodeResumed(p *xml.Decoder, se xml.StartElement) (SMResumed, error) {
+	var packet SMResumed
+	err := p.DecodeElement(&packet, &se)
+	return packet, err
+}
+
+func (smDecoder) decodeRequest(p *xml.Decoder, se xml.StartElement) (SMRequest, error) {
+	var packet SMRequest
+	err := p.DecodeElement(&packet, &se)
+	return packet, err
+}
+
+func (smDecoder) decodeAnswer(p *xml.Decoder, se xml.StartElement) (SMAnswer, error) {
+	var packet SMAnswer
+	err := p.DecodeElement(&packet, &se)
+	return packet, err
+}
+
+func (smDecoder) decodeFailed(p *xml.Decoder, se xml.StartElement) (SMFailed, error) {
+	var packet SMFailed
+	err := p.DecodeElement(&packet, &se)
+	return packet, err
+}