public void AddAnswerAtTime(DNSRecord record, long now)
{
if (now == 0 || !record.IsExpired(now))
{
this.Answers.Add(new Tuple <DNSRecord, long>(record, now));
}
}
/// <summary>
/// Deal with incoming response packets. All answers
/// are held in the cache, and listeners are notified.
/// </summary>
/// <param name="msg">Message.</param>
public void HandleResponse(DNSIncoming msg)
{
long now = Utilities.CurrentTimeMilliseconds();
foreach (DNSRecord record in msg.Answers)
{
bool expired = record.IsExpired(now);
if (this.Cache.Entries().Contains(record))
{
if (expired)
{
this.Cache.Remove(record);
}
else
{
DNSRecord entry = (DNSRecord)this.Cache.Get(record);
if (entry != null)
{
entry.ResetTTL(record);
}
}
}
else
{
this.Cache.Add(record);
}
}
foreach (DNSRecord record in msg.Answers)
{
UpdateRecord(now, record);
}
}
public void AddAnswer(DNSIncoming incoming, DNSRecord record)
{
if (!record.SuppressedBy(incoming))
{
AddAnswerAtTime(record, 0);
}
}
/// <summary>
/// Used to notify listeners of new information that has updated
// a record.
/// </summary>
/// <param name="now">Now.</param>
/// <param name="record">Record.</param>
public void UpdateRecord(long now, DNSRecord record)
{
foreach (IServiceListener l in this.listeners)
{
l.UpdateRecord(this, now, record);
}
NotifyAll();
}
public string ToString(DNSRecord other)
{
long remainingTime = this.GetRemainingTTL(Utilities.CurrentTimeMilliseconds());
String arg = String.Format("{0}/{1},{2}",
this.TTL,
remainingTime,
other);
return(base.ToString("record", arg));
}
/// <summary>
/// Returns a bytearray containing the packet's bytes
///
/// No further parts should be added to the packet once this
/// is done.
/// </summary>
/// <returns>The packet.</returns>
public byte[] Packet()
{
int OverrunAnswers = 0;
int OverrunAuthorities = 0;
int OverrunAdditionals = 0;
if (this.State != State.Finished)
{
// Reserve space for header fields
this.bew.Write(new byte[12]);
foreach (DNSQuestion question in this.Questions)
{
WriteQuestion(question);
}
foreach (Tuple <DNSRecord, long> entry in this.Answers)
{
DNSRecord answer = entry.Item1;
long time = entry.Item2;
OverrunAnswers += WriteRecord(answer, time);
}
foreach (DNSRecord authority in this.Authorities)
{
OverrunAuthorities += WriteRecord(authority, 0);
}
foreach (DNSRecord additional in this.Additionals)
{
OverrunAdditionals += WriteRecord(additional, 0);
}
this.State = State.Finished;
// Write header fields
this.bew.BaseStream.Position = 0;
if (this.Multicast)
{
this.bew.Write((UInt16)0);
}
else
{
this.bew.Write(this.ID);
}
this.bew.Write(this.Flags);
this.bew.Write((UInt16)this.Questions.Count);
this.bew.Write((UInt16)(this.Answers.Count - OverrunAnswers));
this.bew.Write((UInt16)(this.Authorities.Count - OverrunAuthorities));
this.bew.Write((UInt16)(this.Additionals.Count - OverrunAdditionals));
}
return(this.ms.ToArray());
}
/// <summary>
/// Callback invoked by Zeroconf when new information arrives.
/// Updates information required by browser in the Zeroconf cache.
/// </summary>
/// <param name="zc">Zc.</param>
/// <param name="now">Now.</param>
/// <param name="record">Record.</param>
public void UpdateRecord(Zeroconf zc, long now, DNSRecord record)
{
if (record.Type == DNSType.PTR && record.Name == this.type)
{
bool expired = record.IsExpired(now);
string alias = ((DNSPointer)record).Alias;
string serviceKey = alias.ToLower();
DNSRecord oldRecord;
bool success = this.services.TryGetValue(serviceKey, out oldRecord);
if (!success && !expired)
{
this.services[serviceKey] = record;
this.eventArgs.Enqueue(
new Delegates.OnChangeEventArgs(this.type, alias,
ServiceStateChange.Added)
);
}
else if (!expired)
{
oldRecord.ResetTTL(record);
}
else
{
this.services.Remove(serviceKey);
this.eventArgs.Enqueue(
new Delegates.OnChangeEventArgs(this.type, alias,
ServiceStateChange.Removed)
);
return;
}
long expires = record.GetExpirationTime(75);
if (expires < this.nextTime)
{
this.nextTime = expires;
}
}
}
/// <summary>
/// Returns true if another record has same name, type and class,
/// and if its TTL is at least half of this record's
/// </summary>
/// <returns><c>true</c>, if by answer was suppresseded, <c>false</c> otherwise.</returns>
/// <param name="other">Other.</param>
public bool SuppressedByAnswer(DNSRecord other)
{
return(this == other &&
other.TTL > (this.TTL / 2));
}
/// <summary>
/// Sets this record's TTL and created time to that of
/// another record
/// </summary>
/// <param name="other">Other.</param>
public void ResetTTL(DNSRecord other)
{
this.Created = other.Created;
this.TTL = other.TTL;
}
/// <summary>
/// Check wether question is answered by record
/// </summary>
/// <returns>Returns <c>true</c> if question is answered by record,
/// <c>false</c> otherwise/</returns>
/// <param name="record">Record.</param>
public bool AnsweredBy(DNSRecord record)
{
return(base.Class == record.Class &&
(base.Type == record.Type || base.Type == DNSType.ANY) &&
base.Name == record.Name);
}
public bool Request(Zeroconf zc, long timeout)
{
long now = Utilities.CurrentTimeMilliseconds();
long delay = Timing.Listener;
long next = now + delay;
long last = now + timeout;
List <Tuple <DNSType, DNSClass> > recordTypesForCheckCache = new List <Tuple <DNSType, DNSClass> >()
{
new Tuple <DNSType, DNSClass>(DNSType.SRV, DNSClass.IN),
new Tuple <DNSType, DNSClass>(DNSType.TXT, DNSClass.IN),
};
if (this.Server != null)
{
recordTypesForCheckCache.Add(new Tuple <DNSType, DNSClass>(DNSType.A, DNSClass.IN));
}
foreach (Tuple <DNSType, DNSClass> record_type in recordTypesForCheckCache)
{
DNSRecord cached = (DNSRecord)zc.Cache.GetByDetails(this.Name,
record_type.Item1,
record_type.Item2);
if (cached != null)
{
this.UpdateRecord(zc, now, cached);
}
}
if (this.Server != null || this.Address != null || this.Text != null)
{
return(true);
}
try
{
zc.AddListener(this, new DNSQuestion(this.Name, DNSType.ANY, DNSClass.IN));
while (this.Server == null || this.Address == null || this.Text == null)
{
if (last <= now)
{
return(false);
}
if (next <= now)
{
DNSOutgoing outgoing = new DNSOutgoing((ushort)QueryFlags.Query);
outgoing.AddQuestion(
new DNSQuestion(this.Name, DNSType.SRV, DNSClass.IN));
outgoing.AddAnswerAtTime(
(DNSService)zc.Cache.GetByDetails(this.Name, DNSType.SRV, DNSClass.IN),
now
);
outgoing.AddQuestion(
new DNSQuestion(this.Name, DNSType.TXT, DNSClass.IN));
outgoing.AddAnswerAtTime(
(DNSText)zc.Cache.GetByDetails(this.Name, DNSType.TXT, DNSClass.IN),
now
);
if (this.Server != null)
{
outgoing.AddQuestion(
new DNSQuestion(this.Name, DNSType.A, DNSClass.IN));
outgoing.AddAnswerAtTime(
(DNSAddress)zc.Cache.GetByDetails(this.Name, DNSType.A, DNSClass.IN),
now
);
}
zc.Send(outgoing);
next = now + delay;
delay *= 2;
}
zc.Wait(Math.Min(next, last) - now);
now = Utilities.CurrentTimeMilliseconds();
}
}
finally
{
zc.RemoveListener(this);
}
return(true);
}
public void AddAuthorativeAnswer(DNSRecord record)
{
this.Authorities.Add(record);
}
/// <summary>
/// Writes a record (answer, authoritative answer, additional) to
/// the packet
/// </summary>
/// <param name="record">Record.</param>
/// <param name="now">Now.</param>
public int WriteRecord(DNSRecord record, long now)
{
if (this.State == State.Finished)
{
return(1);
}
long StartSize = this.bew.BaseStream.Length;
this.bew.WriteName(record.Name);
this.bew.Write((ushort)record.Type);
if (record.Unique && this.Multicast)
{
this.bew.Write((ushort)((ushort)record.Class | (ushort)DNSClass.UNIQUE));
}
else
{
this.bew.Write((ushort)record.Class);
}
if (now == 0)
{
this.bew.Write(record.TTL);
}
else
{
this.bew.Write((uint)record.GetRemainingTTL(now));
}
// Reserve space for payload size
this.bew.Write((UInt16)0);
// Save old position
long index = this.bew.BaseStream.Position;
// Write payload
record.Write(this.bew);
long payloadSize = this.bew.BaseStream.Position - index;
// Rewind to payload size position
this.bew.BaseStream.Position -= (payloadSize + sizeof(UInt16));
this.bew.Write((UInt16)payloadSize);
// Forward to end of stream
this.bew.BaseStream.Position += payloadSize;
// Need to add headerlength (12) for this check
if ((this.bew.BaseStream.Length + 12) > Constants.MAX_MSG_ABSOLUTE)
{
byte[] newData = new byte[StartSize];
Array.Copy(this.ms.ToArray(), newData, StartSize);
this.ms = new MemoryStream(newData);
this.bew = new BigEndianWriter(this.ms);
this.State = State.Finished;
return(1);
}
return(0);
}
/// <summary>
/// Adds the additional answer.
///
/// From: RFC 6763, DNS-Based Service Discovery, February 2013
///
/// 12. DNS Additional Record Generation
///
/// DNS has an efficiency feature whereby a DNS server may place
/// additional records in the additional section of the DNS message.
/// These additional records are records that the client did not
/// explicitly request, but the server has reasonable grounds to expect
/// that the client might request them shortly, so including them can
/// save the client from having to issue additional queries.
///
/// This section recommends which additional records SHOULD be generated
/// to improve network efficiency, for both Unicast and Multicast DNS-SD
/// responses.
///
/// 12.1. PTR Records
///
/// When including a DNS-SD Service Instance Enumeration or Selective
/// Instance Enumeration (subtype) PTR record in a response packet, the
/// server/responder SHOULD include the following additional records:
///
/// o The SRV record(s) named in the PTR rdata.
/// o The TXT record(s) named in the PTR rdata.
/// o All address records (type "A" and "AAAA") named in the SRV rdata.
///
/// 12.2. SRV Records
///
/// When including an SRV record in a response packet, the
/// server/responder SHOULD include the following additional records:
///
/// o All address records(type "A" and "AAAA") named in the SRV rdata.
/// </summary>
/// <param name="record">Record.</param>
public void AddAdditionalAnswer(DNSRecord record)
{
this.Additionals.Add(record);
}
