IPGlobalProperties.GetActiveTcpListeners() throws System.OverflowException on WSL

[iftahbe]

Running on Ubuntu WSL (Windows Subsystem for Linux):

# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.3 LTS
Release:        16.04
Codename:       xenial

With dotnet (installed via apt-get install dotnet-sdk-2.1):

# dotnet --version
2.1.301

When I run the following console app:

using System;
using System.Net.NetworkInformation;

namespace ConsoleApp3
{
    class Program
    {
        static void Main(string[] args)
        {
            var ipProperties = IPGlobalProperties.GetIPGlobalProperties();
            var activeTcpListeners = ipProperties.GetActiveTcpListeners();
        }
    }
}

I get an exception:

System.OverflowException: Array dimensions exceeded supported range.
   at System.Net.NetworkInformation.StringParsingHelpers.ParseActiveTcpListenersFromFiles(String tcp4ConnectionsFile, String tcp6ConnectionsFile)
   at System.Net.NetworkInformation.LinuxIPGlobalProperties.GetActiveTcpListeners()
   at ConsoleApp3.Program.Main(String[] args) in /home/iftah/test/Program.cs:line 13

[stephentoub]

This appears to be an issue with WSL: both /proc/net/tcp and /proc/net/tcp6 are empty. We should have a better failure mode from GetActiveTcpListeners in that case, but as GetActiveTcpListeners depends on those for the data, if the data isn't available, it probably still needs to throw, but just throw something more informative, like NetworkInformationException.

[wfurt]

we should check if this is still issue.

[ManickaP]

I'll look into it.

[ManickaP]

This does not happen on WSL2, mentioned files are not empty anymore and contain at least the expected header (e.g.: // First line is header in each file.).

I was able to reproduce the issue on WSL1 and the stated method is not the only one having problems.

I'll fix this since the fix is pretty easy.

[ManickaP]

@stephentoub You suggested throwing NetworkInformationException but it inherits from Win32Exception so it might not be the best candidate (as it is right now).

I see 3 options right now:

• split the NetworkInformationException into Win and Linux implementations
• create a new, completely different exception
• use another existing exception, e.g. PlatformNotSupportedException which is already used for when the file doesn't exist

[stephentoub]

it inherits from Win32Exception

We've had to accept the fact that "Win32Exception" is simply poorly named, and it's really "OSException". It works fine on Unix, and is thrown in many other places. It'd be a breaking change to change NetworkInformationException's base type, and NetworkInformationException similarly works fine on Unix.

[ManickaP]

Won't fix as this is only observed only on WSL1 and nowhere else.