private void OnReceive(IAsyncResult ar)
{
lock (this)
{
int length;
try
{
if (_socket == null)
{
return;
}
length = _socket.EndReceive(ar);
}
catch (Exception)
{
return;
}
var stream = new MemoryStream(_buffer, 0, length);
var reader = new DnsMessageReader(stream);
Header header = reader.ReadHeader();
if (header.IsQuery && header.AnswerCount == 0)
{
for (int i = 0; i < header.QuestionCount; i++)
{
Question question = reader.ReadQuestion();
Name serviceName = question.QName;
if (_serviceHandlers.ContainsKey(serviceName))
{
if (header.TransactionID != _lastQueryId)
{
OnServiceQuery(serviceName);
}
}
}
}
if (header.IsResponse && header.IsNoError && header.IsAuthorativeAnswer)
{
for (int i = 0; i < header.QuestionCount; i++)
{
reader.ReadQuestion();
}
_packetServiceInfos.Clear();
_packetHostAddresses.Clear();
for (int i = 0; i < (header.AnswerCount + header.AuthorityCount + header.AdditionalCount); i++)
{
RecordHeader recordHeader = reader.ReadRecordHeader();
if ((recordHeader.Type == RecordType.A) || (recordHeader.Type == RecordType.AAAA)) // A or AAAA
{
IPAddress address = reader.ReadARecord();
if (address.AddressFamily == AddressFamily.InterNetworkV6)
{
if (!NetworkInterface.Information.Supports(NetworkInterfaceComponent.IPv6))
{
continue;
}
// Mono does not support IPv6 properties and always throws NotImplementedException.
// Lets handle the case as with Supports.
try
{
address.ScopeId = NetworkInterface.Information.GetIPProperties().GetIPv6Properties().Index;
}
catch (NotImplementedException)
{
continue;
}
}
OnARecord(recordHeader.Name, address, recordHeader.Ttl);
}
else if ((recordHeader.Type == RecordType.SRV) ||
(recordHeader.Type == RecordType.TXT) ||
(recordHeader.Type == RecordType.PTR))
{
Name serviceName;
Name instanceName;
if (recordHeader.Type == RecordType.PTR)
{
serviceName = recordHeader.Name;
instanceName = reader.ReadPtrRecord();
}
else
{
instanceName = recordHeader.Name;
serviceName = instanceName.SubName(1);
}
if (_serviceHandlers.ContainsKey(serviceName))
{
if (recordHeader.Ttl == 0)
{
PacketRemovesService(instanceName);
}
else
{
ServiceInfo service = FindOrCreatePacketService(instanceName);
if (recordHeader.Type == RecordType.SRV)
{
SrvRecord srvRecord = reader.ReadSrvRecord();
service.HostName = srvRecord.Target;
service.Port = srvRecord.Port;
}
else if (recordHeader.Type == RecordType.TXT)
{
List<string> txts = reader.ReadTxtRecord();
service.Txt = txts;
}
}
}
}
}
HandlePacketHostAddresses();
HandlePacketServiceInfos();
}
StartReceive();
}
}
private void OnReceive(IAsyncResult ar)
#endif
{
lock (this)
{
#if NETSTANDARD1_3
if (args.SocketError != SocketError.Success || _socket == null)
{
return;
}
int length = args.BytesTransferred;
#else
int length;
try
{
if (_socket == null)
{
return;
}
length = _socket.EndReceive(ar);
}
catch (Exception)
{
return;
}
#endif
var stream = new MemoryStream(_buffer, 0, length);
var reader = new DnsMessageReader(stream);
bool validPacket = true;
_packetServiceInfos.Clear();
_packetHostAddresses.Clear();
try
{
Header header = reader.ReadHeader();
if (header.IsQuery && header.AnswerCount == 0)
{
for (int i = 0; i < header.QuestionCount; i++)
{
Question question = reader.ReadQuestion();
Name serviceName = question.QName;
if (_serviceHandlers.ContainsKey(serviceName))
{
if (header.TransactionID != _lastQueryId)
{
OnServiceQuery(serviceName);
}
}
}
}
if (header.IsResponse && header.IsNoError)
{
for (int i = 0; i < header.QuestionCount; i++)
{
reader.ReadQuestion();
}
for (int i = 0; i < (header.AnswerCount + header.AuthorityCount + header.AdditionalCount); i++)
{
RecordHeader recordHeader = reader.ReadRecordHeader();
if ((recordHeader.Type == RecordType.A) || (recordHeader.Type == RecordType.AAAA)) // A or AAAA
{
IPAddress address = reader.ReadARecord();
if (address.AddressFamily == AddressFamily.InterNetworkV6)
{
if (!NetworkInterface.Supports(NetworkInterfaceComponent.IPv6))
{
continue;
}
// Mono does not support IPv6 properties and always throws NotImplementedException.
// Lets handle the case as with Supports.
try
{
address.ScopeId = NetworkInterface.GetIPProperties().GetIPv6Properties().Index;
}
catch (NotImplementedException)
{
continue;
}
}
OnARecord(recordHeader.Name, address, recordHeader.Ttl);
}
else if ((recordHeader.Type == RecordType.SRV) ||
(recordHeader.Type == RecordType.TXT) ||
(recordHeader.Type == RecordType.PTR))
{
Name serviceName;
Name instanceName;
if (recordHeader.Type == RecordType.PTR)
{
serviceName = recordHeader.Name;
instanceName = reader.ReadPtrRecord();
}
else
{
instanceName = recordHeader.Name;
serviceName = instanceName.SubName(1);
}
if (_serviceHandlers.ContainsKey(serviceName))
{
if (recordHeader.Ttl == 0)
{
PacketRemovesService(instanceName);
}
else
{
ServiceInfo service = FindOrCreatePacketService(instanceName);
if (recordHeader.Type == RecordType.SRV)
{
SrvRecord srvRecord = reader.ReadSrvRecord();
service.HostName = srvRecord.Target;
service.Port = srvRecord.Port;
}
else if (recordHeader.Type == RecordType.TXT)
{
List <string> txts = reader.ReadTxtRecord();
service.Txt = txts;
}
}
}
}
}
}
}
catch
{
validPacket = false;
}
if (validPacket)
{
HandlePacketHostAddresses();
HandlePacketServiceInfos();
}
StartReceive();
}
}