/// <summary>
/// Advertise a service profile.
/// </summary>
/// <param name="service">
/// The service profile.
/// </param>
/// <remarks>
/// Any queries for the service or service instance will be answered with
/// information from the profile.
/// <para>
/// Besides adding the profile's resource records to the <see cref="Catalog"/> PTR records are
/// created to support DNS-SD and reverse address mapping (DNS address lookup).
/// </para>
/// </remarks>
public void Advertise(ServiceProfile service)
{
_profiles.Add(service);
var catalog = NameServer.Catalog;
catalog.Add(new PTRRecord {
Name = ServiceName, DomainName = service.QualifiedServiceName
}, true);
catalog.Add(new PTRRecord {
Name = service.QualifiedServiceName, DomainName = service.FullyQualifiedName
}, true);
foreach (var subtype in service.Subtypes)
{
var ptr = new PTRRecord
{
Name = DomainName.Join(new DomainName(subtype), SubName, service.QualifiedServiceName),
DomainName = service.FullyQualifiedName
};
catalog.Add(ptr, true);
}
foreach (var r in service.Resources)
{
catalog.Add(r, true);
}
catalog.IncludeReverseLookupRecords();
}
/// <summary>
/// Sends an unsolicited MDNS response describing the
/// service profile.
/// </summary>
/// <param name="profile">
/// The profile to describe.
/// </param>
/// <remarks>
/// Sends a MDNS response <see cref="Message"/> containing the pointer
/// and resource records of the <paramref name="profile"/>.
/// <para>
/// To provide increased robustness against packet loss,
/// two unsolicited responses are sent one second apart.
/// </para>
/// </remarks>
public void Announce(ServiceProfile profile)
{
var message = new Message {
QR = true
};
// Add the shared records.
var ptrRecord = new PTRRecord {
Name = profile.QualifiedServiceName, DomainName = profile.FullyQualifiedName
};
message.Answers.Add(ptrRecord);
// Add the resource records.
profile.Resources.ForEach((resource) =>
{
message.Answers.Add(resource);
});
message.Questions.Add(new Question()
{
Name = profile.ServiceName,
Class = DnsClass.IN,
Type = DnsType.PTR
});
foreach (var ip in MulticastService.GetLinkLocalAddresses())
{
message.AdditionalRecords.Add(new ARecord()
{
Class = DnsClass.IN,
Type = DnsType.A,
Name = profile.ServiceName,
Address = ip,
TTL = TimeSpan.FromSeconds(120)
});
}
Mdns.Send(message, false);
Task.Delay(1000).Wait();
Mdns.Send(message, false);
}
/// <summary>
/// Sends a goodbye message for the provided
/// profile and removes its pointer from the name sever.
/// </summary>
/// <param name="profile">The profile to send a goodbye message for.</param>
public void UnAdvertise(ServiceProfile profile)
{
var message = new Message {
QR = true
};
var ptrRecord = new PTRRecord {
Name = profile.QualifiedServiceName, DomainName = profile.FullyQualifiedName
};
ptrRecord.TTL = TimeSpan.Zero;
message.Answers.Add(ptrRecord);
profile.Resources.ForEach((resource) =>
{
resource.TTL = TimeSpan.Zero;
message.AdditionalRecords.Add(resource);
});
Mdns.SendAnswer(message);
NameServer.Catalog.TryRemove(profile.QualifiedServiceName, out Node _);
}