runtime: Binding with ReuseAddress not working with UdpClient on Linux

From @olijf on August 30, 2018 11:13

Binding multiple clients on Linux platform in dotnet framework 2.1 does not work as expected

I am binding to a socket with SO_REUSEADDR (MultiCastClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);) but on Linux this gives me an address already in use exception. In dotnet core 2.0 this was working fine.

General

I have the following relevant piece of code:

...
MultiCastClient = new UdpClient();

MultiCastClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
var EndPoint = new IPEndPoint(IPAddress.Any, _listenPort);
MultiCastClient.JoinMulticastGroup(IPAddress.Parse(multicastAddress));

MultiCastClient.Client.Bind(EndPoint); // <--- this is where the bind exception happens.

try
{
	MultiCastClient.BeginReceive(RecieveCallBack, null);
}
...

I have a project targeting netcoreapp2.0

When I am running this with dotnet-hosting-2.0.8 everything is fine. However when I am running this with the newer CLR aspnetcore-runtime-2.1 (all on Debian 9) I am getting a bind exception:

Application startup exception: System.Net.Sockets.SocketException (98): Address already in use
   at System.Net.Sockets.Socket.UpdateStatusAfterSocketErrorAndThrowException(SocketError error, String callerName)
   at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketAddress)
   at System.Net.Sockets.Socket.Bind(EndPoint localEP)
   at UDPNMEAMessageReciever.UdpMessageProcessor.Start()
...

I havent looked into it much further, but I would like to be able to use the newer CLR. Thanks for helping me out here, I really appreciate your efforts.

Copied from original issue: dotnet/coreclr#19765

About this issue

Original URL
State: closed
Created 6 years ago
Comments: 40 (19 by maintainers)

Most upvoted comments

@karelz - I was able to copy over our parts of the UdpClient issue, but not the ones from the others having he same problem.

softworkz on May 25, 2019

Alternatively, you can us the code from https://github.com/dotnet/corefx/issues/32027#issuecomment-417395637

if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
{
    // set SO_REUSEADDR (https://github.com/dotnet/corefx/issues/32027)
    int value = 1;
    setsockopt(MultiCastClient.Client.Handle.ToInt32(), 1, 2, &value, sizeof(int));
}

[DllImport("libc", SetLastError = true)]
private unsafe static extern int setsockopt(int socket, int level, int option_name, void* option_value, uint option_len);

tmds on Sep 5, 2019

Quick update: The workaround was successful in case of my repro scenario. We’re currently adding this to a new beta and then I’ll report back…

softworkz on May 29, 2019

you’re the one who edited the roadmap document

Fair point. It is so long time ago that I forgot 😃, sorry!

karelz on May 29, 2019

You should be able to work around the issue as described here: https://github.com/dotnet/corefx/issues/32027#issuecomment-418082355

tmds on May 25, 2019

@karelz when the PR is merged on master, will it become part of the 2.2 release? Can we consider this for 2.1?

@olijf by adding the setsockopt(s.Handle.ToInt32(), 1, 2, &value, sizeof(int)); you should be able to unblock yourself. Please give it a try, an confirm that resolves the issue.

peudo code:

UdpClient MultiCastClient = new UdpClient();
MultiCastClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
{
    // set SO_REUSEADDR (https://github.com/dotnet/corefx/issues/32027)
    int value = 1;
    setsockopt(MultiCastClient.Client.Handle.ToInt32(), 1, 2, &value, sizeof(int));
}

[DllImport("libc", SetLastError = true)]
private unsafe static extern int setsockopt(int socket, int level, int option_name, void* option_value, uint option_len);

tmds on Sep 3, 2018