/
stream.go
163 lines (137 loc) · 3.19 KB
/
stream.go
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package xmpp
import (
"encoding/xml"
"io"
"sync"
)
// Stream manages a bidirectional XMPP stream using an underlying transport
type Stream struct {
transport io.ReadWriter
decoder *xml.Decoder
encoder *xml.Encoder
streamEnd xml.EndElement
mu sync.Mutex
}
type Reader interface {
Read() (interface{}, error)
}
type Writer interface {
Write(interface{}) error
}
type Closer interface {
Close() error
}
type ReadWriter interface {
Reader
Writer
}
type ReadWriteCloser interface {
Reader
Writer
Closer
}
// NewStream instantiates a new stream using the provided transport
func NewStream(transport io.ReadWriter) *Stream {
return &Stream{
transport: transport,
decoder: xml.NewDecoder(transport),
encoder: xml.NewEncoder(transport),
}
}
// Transport returns the underlying transport object
func (s *Stream) Transport() io.ReadWriter {
return s.transport
}
// Read reads and returns a message from the stream
func (s *Stream) Read() (interface{}, error) {
for {
token, err := s.decoder.Token()
if err != nil {
return nil, err
}
switch typed := token.(type) {
case xml.StartElement:
p := &proxy{}
s.decoder.DecodeElement(p, &typed)
return p.Object, nil
case xml.EndElement: // </stream>
return nil, ErrEndOfStream
case xml.CharData:
// Ignore character data
default:
return nil, ErrStreamError
}
}
}
// Close closes the XMPP stream. No writes can be performed afterwards.
func (s *Stream) Close() error {
err := s.writeStreamEnd()
s.encoder = nil
return err
}
// Write writes an XMPP message to the stream
func (s *Stream) Write(msg interface{}) error {
// Lock the stream for writing
s.mu.Lock()
defer s.mu.Unlock()
if err := s.encoder.Encode(msg); err != nil {
return err
}
return s.encoder.Flush()
}
// WriteHeader writes a stream header to the stream.
func (s *Stream) WriteHeader(stream *StreamHeader) error {
// Lock the stream for writing
s.mu.Lock()
defer s.mu.Unlock()
// Write ProcInst (<?xml version="1.0"?>)
err := s.encoder.EncodeToken(xml.ProcInst{
Target: "xml",
Inst: []byte(`version="1.0"`),
})
if err != nil {
return err
}
// Open the stream element and keep the closing tag for later
start := stream.XMLStartElement()
s.streamEnd = start.End() // Store matching end element
err = s.encoder.EncodeToken(start)
if err != nil {
return err
}
return s.encoder.Flush()
}
// ReadHeader reads and returns a stream header. It ignores the first ProcInst
// read from the stream.
func (s *Stream) ReadHeader() (*StreamHeader, error) {
allowProcInst := true
for {
token, err := s.decoder.Token()
if err != nil {
return nil, err
}
switch typed := token.(type) {
case xml.ProcInst:
if !allowProcInst {
return nil, ErrStreamError
}
allowProcInst = false
case xml.StartElement:
allowProcInst = false // PI is only valid before other elements
return ParseStreamHeader(&typed), nil
default:
return nil, ErrStreamError
}
}
}
// writeStreamEnd writes the XMPP stream end element
func (s *Stream) writeStreamEnd() error {
// Lock the stream for writing
s.mu.Lock()
defer s.mu.Unlock()
err := s.encoder.EncodeToken(s.streamEnd)
if err != nil {
return err
}
return s.encoder.Flush()
}