Extend BIND syntax to support timebounding

Goal: cache responses from upstream servers respecting TTL
Complete port of System.Runtime.Caching to .NET Core 2.2, test and integrate.

Parser for BIND zone file syntax

MAC addresses
Debug output
console spew etc.

Enable plugins to get configuration from a namespace in application YAML configuration

Work required to make the service run in CoreCLR on non-Windows platforms.

Replace VS test frameworks with xUnit to enable cross platform build verification

Possible bug in implementation of Bitpacker.Write. Check usage.

Current the health check system uses HTTP on a well-known port, with a well-known URL to check for server status. This work item would change this into a configureable and pluggable pass/fail protocol.

Specifically in line 63 of the DnsProtocol class (ReadString method). According to the RFC1035 when you encounter a pointer (denoted through the top two bits set to 1) the lower remaining 6 bytes should form a 14 bit offset with the next octet. Currently you ignore the remaining 6 bits and just read the next byte as offset. That byte does represent the lower 8 bits of the offset and would work as long as you don't encounter any offset to a position greater than 255

Specifically this line:
currentOffset = bytes[currentOffset];

Should read

currentOffset = bytes[currentOffset] | (segmentLength & 0x3F)<<8;

So we simply add the 6 bits of the first byte as the high order bits of the second byte to get our 14 bit offset.

Of course for UDP requests we are limited to 512 octets. So we would need at max the lowest additional bit from those 6 bits. However TCP requests could be longer

The method Start when the HttpServer is enabled isn't invoked.

Adding _listener.Start() there is an exception, because the URI must be registered using netsh in the Windows platform.

netsh http add urlacl url=http://+:8080/ user=BUILTIN\Users

Look for free and open source of parental control domains.

Outdated sources.

I detected a race condition in your parsing logic of the dns messages.

You pass the SocketAsyncEventArgs object directly to the method OnRequest which will be processed in a new thread.

Right before or during the processing happens another DNS message could be received which will change the content of the buffer inside the SocketAsyncEventArgs so the already running thread parsing the first message will likely see parts of the new message if it's not done yet.

This happened in my case, where my linux device send two requests in parallel one "IN A" and "IN AAAA". The first message received was the "IN A" request but right before the parser came to the point to read the type of the request the second message changed the buffer and the type was read as "AAAA".

You should consider to copy the content of the received data to a new buffer and pass that to your parser for example like so:

if (OnRequest != null)
{
	var buffer = new byte[bytesRead];
	Buffer.BlockCopy(args.Buffer, 0, buffer, 0, buffer.Length);
	var process = Task.Run(() => OnRequest(args, buffer));
}

This ensures that each thread has it's own data and that args.Buffer is not accessed in parallel from multiple threads at the same time.

Regardless of this issue, your DNS server helped my to diagnose a little issue on my linux device. I used it to check which exact requests are send. Thanks for the great work!

Pluggable configuration provider that can fetch from non-file sources e.g. HTTP and Git.

$ mono Dns.exe 

Unhandled Exception:
System.IO.FileNotFoundException: filename not found
File name: '/var/calculate/remote/distfiles/egit-src/csharp-dns-server.git/Dns/bin/Debug/d:\data\machineinfo.csv'
  at Dns.ZoneProvider.FileWatcherZoneProvider..ctor (System.String filename) <0x40ca25d0 + 0x00bef> in :0 
  at Dns.ZoneProvider.AP.APZoneProvider..ctor (System.String machineInfoFile, System.String zoneSuffix) <0x40ca24a0 + 0x0001f> in :0 
  at Dns.Program.Main (System.String[] args) <0x40c7a8b0 + 0x000c7> in :0 
[ERROR] FATAL UNHANDLED EXCEPTION: Nested exception trying to figure out what went wrong

Scenario: Little Timmy tries to surf Facebook on his laptop, it fails for him. Little Timmy's mother surfs Facebook on the desktop and it works just fine.

Add support for exposure of data as prometheus endpoint

Enable Application to load configuration from Kubernetes Style Config Map.

Reload configuration if it changes on disk