/// <summary>
/// Selects a stream-method from the list of advertised methods.
/// </summary>
/// <param name="feature">The 'feature' element containing the data-form
/// with advertised stream-methods.</param>
/// <returns>The selected stream-method.</returns>
/// <exception cref="ArgumentException">None of the advertised methods is
/// supported.</exception>
string SelectStreamMethod(XmlElement feature)
{
// See if we support any of the advertised stream-methods.
DataForm form = FeatureNegotiation.Parse(feature);
ListField field = form.Fields["stream-method"] as ListField;
// Order of preference: Socks5, Ibb.
string[] methods = new string[] {
"http://jabber.org/protocol/bytestreams",
"http://jabber.org/protocol/ibb"
};
for (int i = 0; i < methods.Length; i++)
{
if (ForceInBandBytestreams &&
methods[i] != "http://jabber.org/protocol/ibb")
{
continue;
}
if (field.Values.Contains(methods[i]))
{
return(methods[i]);
}
}
throw new ArgumentException("No supported method advertised.");
}
/// <summary>
/// Parses the selected stream-method from the specified 'feature' XML
/// element.
/// </summary>
/// <param name="feature">The 'feature' XML element.</param>
/// <returns>The stream method contained in the 'feature' XML
/// element.</returns>
/// <exception cref="ArgumentNullException">The feature parameter is
/// null.</exception>
/// <exception cref="ArgumentException">The feature element contains
/// invalid data.</exception>
string ParseStreamMethod(XmlElement feature)
{
feature.ThrowIfNull("feature");
DataForm form = FeatureNegotiation.Parse(feature);
// The data-form must contain a field named 'stream-method'.
var field = form.Fields["stream-method"];
if (field == null)
{
throw new ArgumentException("Missing or erroneous 'stream-method' field.");
}
string selected = field.Values.FirstOrDefault();
if (selected == null)
{
throw new ArgumentException("No stream-method selected.");
}
return(selected);
}
