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DnsServer: reusing memory stream in ReadUdpRequestAsync(). Updated ProcessAPPAsync() to return server failure when app or class path is not found. Updated CachePrefetchRefreshTimerCallback() and RefreshCacheAsync() to prevent double refresh attempts. Updated CachePrefetchRefreshTimerCallback() to use threadpool tasks for better concurrency. Updated CacheMaintenanceTimerCallback() to reset due time in finally for next interval callback and using sync lock. Fixed bug in UpdateThisServer() logic.

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This commit is contained in:
Shreyas Zare
2021-04-10 13:58:48 +05:30
parent be9ff3ea75
commit f5da78c579
1 changed files with 95 additions and 50 deletions
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145
DnsServerCore/Dns/DnsServer.cs
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@@ -128,6 +128,7 @@ namespace DnsServerCore.Dns
IList<CacheRefreshSample> _cacheRefreshSampleList;
Timer _cacheMaintenanceTimer;
readonly object _cacheMaintenanceTimerLock = new object();
const int CACHE_MAINTENANCE_TIMER_INITIAL_INTEVAL = 15 * 60 * 1000;
const int CACHE_MAINTENANCE_TIMER_PERIODIC_INTERVAL = 15 * 60 * 1000;
@@ -229,7 +230,9 @@ namespace DnsServerCore.Dns
private async Task ReadUdpRequestAsync(Socket udpListener)
{
byte[] recvBuffer = new byte[1500];
const int BUFFER_SIZE = 512;
byte[] recvBuffer = new byte[BUFFER_SIZE];
MemoryStream recvBufferStream = new MemoryStream(recvBuffer);
try
{
@@ -253,6 +256,8 @@ namespace DnsServerCore.Dns
while (true)
{
recvBufferStream.SetLength(BUFFER_SIZE); //resetting length before using buffer
try
{
result = await udpListener.ReceiveFromAsync(recvBuffer, SocketFlags.None, epAny);
@@ -277,12 +282,12 @@ namespace DnsServerCore.Dns
{
try
{
using (MemoryStream mS = new MemoryStream(recvBuffer, 0, result.ReceivedBytes, false))
{
DnsDatagram request = DnsDatagram.ReadFromUdp(mS);
recvBufferStream.Position = 0;
recvBufferStream.SetLength(result.ReceivedBytes);
_ = ProcessUdpRequestAsync(udpListener, result.RemoteEndPoint as IPEndPoint, request);
}
DnsDatagram request = DnsDatagram.ReadFromUdp(recvBufferStream);
_ = ProcessUdpRequestAsync(udpListener, result.RemoteEndPoint as IPEndPoint, request);
}
catch (EndOfStreamException)
{
@@ -325,9 +330,12 @@ namespace DnsServerCore.Dns
else
{
//format error
LogManager log = _log;
if (log != null)
log.Write(remoteEP, DnsTransportProtocol.Udp, request.ParsingException);
if (!(request.ParsingException is IOException))
{
LogManager log = _log;
if (log != null)
log.Write(remoteEP, DnsTransportProtocol.Udp, request.ParsingException);
}
//format error response
response = new DnsDatagram(request.Identifier, true, request.OPCODE, false, false, request.RecursionDesired, IsRecursionAllowed(remoteEP), false, false, DnsResponseCode.FormatError, request.Question);
@@ -540,9 +548,12 @@ namespace DnsServerCore.Dns
if (queryLog != null)
queryLog.Write(remoteEP, protocol, request, response);
LogManager log = _log;
if (log != null)
log.Write(remoteEP, protocol, request.ParsingException);
if (!(request.ParsingException is IOException))
{
LogManager log = _log;
if (log != null)
log.Write(remoteEP, protocol, request.ParsingException);
}
}
//send response
@@ -684,9 +695,9 @@ namespace DnsServerCore.Dns
if (strContentType != "application/dns-message")
throw new NotSupportedException("DNS request type not supported: " + strContentType);
using (MemoryStream mS = new MemoryStream())
using (MemoryStream mS = new MemoryStream(32))
{
await httpRequest.InputStream.CopyToAsync(mS, 512);
await httpRequest.InputStream.CopyToAsync(mS, 32);
mS.Position = 0;
dnsRequest = DnsDatagram.ReadFromUdp(mS);
@@ -707,9 +718,12 @@ namespace DnsServerCore.Dns
else
{
//format error
LogManager log = _log;
if (log != null)
log.Write(remoteEP, protocol, dnsRequest.ParsingException);
if (!(dnsRequest.ParsingException is IOException))
{
LogManager log = _log;
if (log != null)
log.Write(remoteEP, protocol, dnsRequest.ParsingException);
}
//format error response
dnsResponse = new DnsDatagram(dnsRequest.Identifier, true, dnsRequest.OPCODE, false, false, dnsRequest.RecursionDesired, IsRecursionAllowed(remoteEP), false, false, DnsResponseCode.FormatError, dnsRequest.Question);
@@ -717,12 +731,12 @@ namespace DnsServerCore.Dns
if (dnsResponse != null)
{
using (MemoryStream mS = new MemoryStream())
using (MemoryStream mS = new MemoryStream(512))
{
dnsResponse.WriteToUdp(mS);
byte[] buffer = mS.ToArray();
await SendContentAsync(stream, requestConnection, "application/dns-message", buffer);
mS.Position = 0;
await SendContentAsync(stream, requestConnection, "application/dns-message", mS);
}
LogManager queryLog = _queryLog;
@@ -753,14 +767,14 @@ namespace DnsServerCore.Dns
DnsDatagram dnsResponse = await ProcessQueryAsync(dnsRequest, remoteEP, IsRecursionAllowed(remoteEP), protocol);
if (dnsResponse != null)
{
using (MemoryStream mS = new MemoryStream())
using (MemoryStream mS = new MemoryStream(512))
{
JsonTextWriter jsonWriter = new JsonTextWriter(new StreamWriter(mS));
dnsResponse.WriteToJson(jsonWriter);
jsonWriter.Flush();
byte[] buffer = mS.ToArray();
await SendContentAsync(stream, requestConnection, "application/dns-json; charset=utf-8", buffer);
mS.Position = 0;
await SendContentAsync(stream, requestConnection, "application/dns-json; charset=utf-8", mS);
}
LogManager queryLog = _queryLog;
@@ -832,12 +846,12 @@ namespace DnsServerCore.Dns
}
}
private static async Task SendContentAsync(Stream outputStream, string connection, string contentType, byte[] bufferContent)
private static async Task SendContentAsync(Stream outputStream, string connection, string contentType, Stream content)
{
byte[] bufferHeader = Encoding.UTF8.GetBytes("HTTP/1.1 200 OK\r\nDate: " + DateTime.UtcNow.ToString("r") + "\r\nContent-Type: " + contentType + "\r\nContent-Length: " + bufferContent.Length + "\r\nX-Robots-Tag: noindex, nofollow\r\nConnection: " + connection + "\r\n\r\n");
byte[] bufferHeader = Encoding.UTF8.GetBytes("HTTP/1.1 200 OK\r\nDate: " + DateTime.UtcNow.ToString("r") + "\r\nContent-Type: " + contentType + "\r\nContent-Length: " + content.Length + "\r\nX-Robots-Tag: noindex, nofollow\r\nConnection: " + connection + "\r\n\r\n");
await outputStream.WriteAsync(bufferHeader);
await outputStream.WriteAsync(bufferContent);
await content.CopyToAsync(outputStream);
await outputStream.FlushAsync();
}
@@ -964,7 +978,7 @@ namespace DnsServerCore.Dns
catch (InvalidDomainNameException)
{
//format error response
return new DnsDatagram(request.Identifier, true, request.OPCODE, false, false, request.RecursionDesired, IsRecursionAllowed(remoteEP), false, false, DnsResponseCode.FormatError, request.Question);
return new DnsDatagram(request.Identifier, true, request.OPCODE, false, false, request.RecursionDesired, isRecursionAllowed, false, false, DnsResponseCode.FormatError, request.Question);
}
catch (Exception ex)
{
@@ -1153,7 +1167,14 @@ namespace DnsServerCore.Dns
AuthZoneInfo zoneInfo = _authZoneManager.GetAuthZoneInfo(appResourceRecord.Name);
DnsDatagram appResponse = await appRequestHandler.ProcessRequestAsync(request, remoteEP, zoneInfo.Name, appResourceRecord.TtlValue, appRecord.Data, isRecursionAllowed, application.DnsServer);
if (appResponse != null)
if (appResponse == null)
{
//return no error response with SOA
IReadOnlyList<DnsResourceRecord> authority = zoneInfo.GetRecords(DnsResourceRecordType.SOA);
return new DnsDatagram(request.Identifier, true, request.OPCODE, false, false, request.RecursionDesired, isRecursionAllowed, false, false, DnsResponseCode.NoError, request.Question, null, authority);
}
else
{
if (appResponse.AuthoritativeAnswer)
appResponse.Tag = StatsResponseType.Authoritative;
@@ -1175,12 +1196,12 @@ namespace DnsServerCore.Dns
log.Write(remoteEP, protocol, "DNS application '" + appRecord.AppName + "' was not found: " + appResourceRecord.Name);
}
//return no error response with SOA
//return server failure response with SOA
{
AuthZoneInfo zoneInfo = _authZoneManager.GetAuthZoneInfo(request.Question[0].Name);
IReadOnlyList<DnsResourceRecord> authority = zoneInfo.GetRecords(DnsResourceRecordType.SOA);
return new DnsDatagram(request.Identifier, true, request.OPCODE, false, false, request.RecursionDesired, isRecursionAllowed, false, false, DnsResponseCode.NoError, request.Question, null, authority);
return new DnsDatagram(request.Identifier, true, request.OPCODE, false, false, request.RecursionDesired, isRecursionAllowed, false, false, DnsResponseCode.ServerFailure, request.Question, null, authority);
}
}
@@ -1883,27 +1904,29 @@ namespace DnsServerCore.Dns
DnsDatagram request = new DnsDatagram(0, false, DnsOpcode.StandardQuery, false, false, true, false, false, false, DnsResponseCode.NoError, new DnsQuestionRecord[] { sample.SampleQuestion });
DnsDatagram response = await ProcessRecursiveQueryAsync(request, new IPEndPoint(IPAddress.Any, 0), DnsTransportProtocol.Udp, sample.ViaForwarders, true);
bool removeFromSampleList = true;
bool addBackToSampleList = false;
DateTime utcNow = DateTime.UtcNow;
foreach (DnsResourceRecord answer in response.Answer)
{
if ((answer.OriginalTtlValue > _cachePrefetchEligibility) && (utcNow.AddSeconds(answer.TtlValue) < _cachePrefetchSamplingTimerTriggersOn))
{
//answer expires before next sampling so dont remove from list to allow refreshing it
removeFromSampleList = false;
//answer expires before next sampling so add back to the list to allow refreshing it
addBackToSampleList = true;
break;
}
}
if (removeFromSampleList)
cacheRefreshSampleList[sampleQuestionIndex] = null;
if (addBackToSampleList)
cacheRefreshSampleList[sampleQuestionIndex] = sample; //put back into sample list to allow refreshing it again
}
catch (Exception ex)
{
LogManager log = _log;
if (log != null)
log.Write(ex);
cacheRefreshSampleList[sampleQuestionIndex] = sample; //put back into sample list to allow refreshing it again
}
}
@@ -2094,7 +2117,10 @@ namespace DnsServerCore.Dns
if (!IsCacheRefreshNeeded(sample.SampleQuestion, _cachePrefetchTrigger + 2))
continue;
_ = RefreshCacheAsync(cacheRefreshSampleList, sample, i);
cacheRefreshSampleList[i] = null; //remove from sample list to avoid concurrent refresh attempt
int sampleQuestionIndex = i;
_ = Task.Run(delegate () { return RefreshCacheAsync(cacheRefreshSampleList, sample, sampleQuestionIndex); }); //run task in threadpool since its long running
}
}
}
@@ -2126,6 +2152,14 @@ namespace DnsServerCore.Dns
if (log != null)
log.Write(ex);
}
finally
{
lock (_cacheMaintenanceTimerLock)
{
if (_cacheMaintenanceTimer != null)
_cacheMaintenanceTimer.Change(CACHE_MAINTENANCE_TIMER_PERIODIC_INTERVAL, Timeout.Infinite);
}
}
}
private void ResetPrefetchTimers()
@@ -2165,20 +2199,28 @@ namespace DnsServerCore.Dns
private void UpdateThisServer()
{
if (_thisServer == null)
if ((_localEndPoints == null) || (_localEndPoints.Count == 0))
{
if ((_localEndPoints == null) || (_localEndPoints.Count == 0))
_thisServer = new NameServerAddress(_serverDomain, IPAddress.Loopback);
else if (_localEndPoints[0].Address.Equals(IPAddress.Any))
_thisServer = new NameServerAddress(_serverDomain, new IPEndPoint(IPAddress.Loopback, _localEndPoints[0].Port));
else if (_localEndPoints[0].Equals(IPAddress.IPv6Any))
_thisServer = new NameServerAddress(_serverDomain, new IPEndPoint(IPAddress.IPv6Loopback, _localEndPoints[0].Port));
else
_thisServer = new NameServerAddress(_serverDomain, _localEndPoints[0]);
_thisServer = new NameServerAddress(_serverDomain, IPAddress.Loopback);
}
else
{
_thisServer = new NameServerAddress(_serverDomain, _thisServer.IPEndPoint);
foreach (IPEndPoint localEndPoint in _localEndPoints)
{
if (localEndPoint.Address.Equals(IPAddress.Any))
{
_thisServer = new NameServerAddress(_serverDomain, new IPEndPoint(IPAddress.Loopback, localEndPoint.Port));
return;
}
if (localEndPoint.Address.Equals(IPAddress.IPv6Any))
{
_thisServer = new NameServerAddress(_serverDomain, new IPEndPoint(IPAddress.IPv6Loopback, localEndPoint.Port));
return;
}
}
_thisServer = new NameServerAddress(_serverDomain, _localEndPoints[0]);
}
}
@@ -2449,7 +2491,7 @@ namespace DnsServerCore.Dns
_cachePrefetchSamplingTimer = new Timer(CachePrefetchSamplingTimerCallback, null, Timeout.Infinite, Timeout.Infinite);
_cachePrefetchRefreshTimer = new Timer(CachePrefetchRefreshTimerCallback, null, Timeout.Infinite, Timeout.Infinite);
_cacheMaintenanceTimer = new Timer(CacheMaintenanceTimerCallback, null, CACHE_MAINTENANCE_TIMER_INITIAL_INTEVAL, CACHE_MAINTENANCE_TIMER_PERIODIC_INTERVAL);
_cacheMaintenanceTimer = new Timer(CacheMaintenanceTimerCallback, null, CACHE_MAINTENANCE_TIMER_INITIAL_INTEVAL, Timeout.Infinite);
_state = ServiceState.Running;
@@ -2482,10 +2524,13 @@ namespace DnsServerCore.Dns
}
}
if (_cacheMaintenanceTimer != null)
lock (_cacheMaintenanceTimerLock)
{
_cacheMaintenanceTimer.Dispose();
_cacheMaintenanceTimer = null;
if (_cacheMaintenanceTimer != null)
{
_cacheMaintenanceTimer.Dispose();
_cacheMaintenanceTimer = null;
}
}
foreach (Socket udpListener in _udpListeners)