go-xmpp/parser.go
genofire d9fdff0839 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
2019-06-22 11:13:33 +02:00

152 lines
4.3 KiB
Go

package xmpp
import (
"encoding/xml"
"errors"
"fmt"
"io"
)
// Reads and checks the opening XMPP stream element.
// TODO It returns a stream structure containing:
// - Host: You can check the host against the host you were expecting to connect to
// - Id: the Stream ID is a temporary shared secret used for some hash calculation. It is also used by ProcessOne
// 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 initStream(p *xml.Decoder) (sessionID string, err error) {
for {
var t xml.Token
t, err = p.Token()
if err != nil {
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 sessionID, err
}
// Parse XMPP stream attributes
for _, attrs := range elem.Attr {
switch attrs.Name.Local {
case "id":
sessionID = attrs.Value
}
}
return sessionID, err
}
}
}
// Scan XML token stream to find next StartElement.
func nextStart(p *xml.Decoder) (xml.StartElement, error) {
for {
t, err := p.Token()
if err == io.EOF {
return xml.StartElement{}, errors.New("connection closed")
}
if err != nil {
return xml.StartElement{}, fmt.Errorf("nextStart %s", err)
}
switch t := t.(type) {
case xml.StartElement:
return t, nil
}
}
}
// 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
// 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 {
return nil, err
}
// Decode one of the top level XMPP namespace
switch se.Name.Space {
case NSStream:
return decodeStream(p, se)
case nsSASL:
return decodeSASL(p, se)
case NSClient:
return decodeClient(p, se)
case NSComponent:
return decodeComponent(p, se)
default:
return nil, errors.New("unknown namespace " +
se.Name.Space + " <" + se.Name.Local + "/>")
}
}
/*
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":
return streamError.decode(p, se)
case "features":
return streamFeatures.decode(p, se)
default:
return nil, errors.New("unexpected XMPP packet " +
se.Name.Space + " <" + se.Name.Local + "/>")
}
}
// decodeSASL decodes a packet related to SASL authentication.
func decodeSASL(p *xml.Decoder, se xml.StartElement) (Packet, error) {
switch se.Name.Local {
case "success":
return saslSuccess.decode(p, se)
case "failure":
return saslFailure.decode(p, se)
default:
return nil, errors.New("unexpected XMPP packet " +
se.Name.Space + " <" + se.Name.Local + "/>")
}
}
// 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":
return message.decode(p, se)
case "presence":
return presence.decode(p, se)
case "iq":
return iq.decode(p, se)
default:
return nil, errors.New("unexpected XMPP packet " +
se.Name.Space + " <" + se.Name.Local + "/>")
}
}
// 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": // handshake is used to authenticate components
return handshake.decode(p, se)
case "message":
return message.decode(p, se)
case "presence":
return presence.decode(p, se)
case "iq":
return iq.decode(p, se)
default:
return nil, errors.New("unexpected XMPP packet " +
se.Name.Space + " <" + se.Name.Local + "/>")
}
}