Don't bind to IPv6 when the OS doesn't support it

[pavelsavara]

Contributes to dotnet/runtime#122435

[pavelsavara]

Alternatively we can also/instead just change

aspnetcore/src/Servers/Kestrel/Transport.Sockets/src/SocketTransportOptions.cs

Line 146 in c9d0750

if (ip.Address.Equals(IPAddress.IPv6Any))

            case IPEndPoint ip:
                listenSocket = new Socket(ip.AddressFamily, SocketType.Stream, ProtocolType.Tcp);

                // Kestrel expects IPv6Any to bind to both IPv6 and IPv4
-                if (ip.Address.Equals(IPAddress.IPv6Any))
+                if (Socket.OSSupportsIPv6 && ip.Address.Equals(IPAddress.IPv6Any))

[Copilot]

Pull request overview

This PR addresses the issue of Kestrel attempting to bind to IPv6 addresses on systems that don't support IPv6. The change proactively checks Socket.OSSupportsIPv6 before attempting to bind, avoiding unnecessary binding failures and the associated fallback mechanism.

Key Changes:

• Modified AnyIPListenOptions constructor to check IPv6 support before choosing the IP address type
• Added test coverage for non-IPv6 environments using RemoteExecutor
• Added Microsoft.DotNet.RemoteExecutor package reference for testing

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/Servers/Kestrel/Core/src/AnyIPListenOptions.cs	Updated constructor to check Socket.OSSupportsIPv6 and use IPAddress.Any when IPv6 is not supported, otherwise use IPAddress.IPv6Any
src/Servers/Kestrel/Core/test/AddressBinderTests.cs	Added new test ParseAddressOnOSWithoutIPv6 using RemoteExecutor to verify behavior on systems without IPv6 support
src/Servers/Kestrel/Core/test/Microsoft.AspNetCore.Server.Kestrel.Core.Tests.csproj	Added reference to Microsoft.DotNet.RemoteExecutor package for testing

[pavelsavara]