// Start starts or restarts the stream.
//
// In recieving mode, the transport will wait to recieve a stream header
// from the initiating entity, then sends its own header and the stream
// features. This transport will add the starttls feature under certain
// conditions.
func (t *TCP) Start(props stream.Properties) (stream.Properties, error) {
if t.mode == stream.Initiating {
if props.Header == (stream.Header{}) {
return props, stream.ErrHeaderNotSet
}
b := props.Header.WriteBytes()
_, err := t.Write(b)
return props, err
}
// We're in recieving mode
if props.Domain == "" {
return props, stream.ErrDomainNotSet
}
var el element.Element
var h stream.Header
var err error
el, err = t.Next()
if err != nil {
return props, err
}
h, err = stream.NewHeader(el)
if err != nil {
return props, err
}
h.ID = genStreamID()
if h.To != props.Domain {
h.To, h.From = h.From, props.Domain
b := h.WriteBytes()
t.Write(b)
err = t.WriteElement(element.StreamError.HostUnknown)
props.Status = stream.Closed
return props, err
}
h.From, h.To = props.Domain, h.From
if props.To != "" {
h.To = props.To
}
props.Header = h
b := props.Header.WriteBytes()
_, err = t.Write(b)
if err != nil {
return props, err
}
ftrs := element.StreamFeatures
for _, f := range props.Features {
ftrs = ftrs.AddChild(f)
}
// Stream features
if t.conf != nil && !t.secure {
tlsFeature := element.StartTLS
if t.tlsRequired {
tlsFeature = tlsFeature.AddChild(element.Required)
}
// Overwrite any other features
ftrs.Child = []element.Token{tlsFeature}
}
err = t.WriteElement(ftrs)
return props, err
}
