Access Violation on call to DsAddressToSiteNames

[ryannewington]

Describe the bug and how to reproduce

When passing an array of SOCKET_ADDRESS to DsAddressToSiteNames either an access violation or win32 (1783) error (The stub received bad data) is throw.

What code is involved

The header for SOCKET_ADDRESS is as follows

[StructLayout(LayoutKind.Sequential,
#if x64
	Size = 16)]
#else
	Size = 8)]
#endif
	public struct SOCKET_ADDRESS

However, there appears to be no compiler definition for x64 and therefore, the layout size is always set to 8. If you compile your app to run 32-bit it succeeds. If you compile as AnyCPU or x64, it fails.

Vanara/PInvoke/Ws2_32/ws2def.cs

Line 1716 in d1d0ff5

public struct SOCKET_ADDRESS

Changing this struct value manually works.

Expected behavior

The call should succeed on both x86 an x64 builds.

Repo sample

Modify the dcname variable below with the name of a domain controller to reproduce the issue.
Running as x64 fails, running as x86 succeeds

using System.Net;
using System.Runtime.InteropServices;
using Vanara.Extensions;
using Vanara.PInvoke;
using static Vanara.PInvoke.NetApi32;
using static Vanara.PInvoke.Ws2_32;

internal class Program
{
    private static void Main(string[] args)
    {
        string dcname = "dc1";

        Ws2_32.WSAStartup(2, out _);
        List<IPAddress> ipAddresses;

        try
        {
            // fails
            ipAddresses = new List<IPAddress>() { IPAddress.Parse("127.0.0.1"), IPAddress.Parse("::1") };
            GetSites(ipAddresses, dcname);
        }

        catch (Exception ex)
        {
            Console.WriteLine("lookup failed\r\n{0}", ex);
        }

        Console.WriteLine("=======================================================\r\n");

        try
        {
            // works
            ipAddresses = new List<IPAddress>() { IPAddress.Parse("127.0.0.1") };
            GetSites(ipAddresses, dcname);
        }
        catch (Exception ex)
        {
            Console.WriteLine("lookup failed\r\n{0}", ex);
        }

        Console.WriteLine("=======================================================\r\n");

        try
        {
            // works
            ipAddresses = new List<IPAddress>() { IPAddress.Parse("::1") };
            GetSites(ipAddresses, dcname);
        }
        catch (Exception ex)
        {
            Console.WriteLine("lookup failed\r\n{0}", ex);
        }

        Console.WriteLine("=======================================================\r\n");


        Console.WriteLine("press any key to exit");
        Console.ReadLine();
    }

    private static void GetSites(List<IPAddress> ipAddresses, string dcname)
    {
        List<Ws2_32.SOCKADDR> resolvedAddresses = new List<Ws2_32.SOCKADDR>();

        foreach (IPAddress ipAddress in ipAddresses.OrderBy(t => (int)t.AddressFamily))
        {
            Ws2_32.SOCKADDR socketAddress;

            if (ipAddress.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
            {
                socketAddress = new Ws2_32.SOCKADDR_IN();
            }
            else if (ipAddress.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6)
            {
                socketAddress = new Ws2_32.SOCKADDR_IN6();
            }
            else
            {
                Console.WriteLine("Ignoring unknown address type {0}", ipAddress.AddressFamily.ToString());
                continue;
            }

            int length = socketAddress.Size;
            string addr = ipAddress.ToString();

            var wsresult = Ws2_32.WSAStringToAddress(addr, (Ws2_32.ADDRESS_FAMILY)ipAddress.AddressFamily, IntPtr.Zero, socketAddress, ref length);

            if (wsresult.Failed)
            {
                Console.WriteLine("WSAStringToAddress failed\r\n{0}", wsresult.GetException());
            }

            resolvedAddresses.Add(socketAddress);
        }

        if (resolvedAddresses.Count == 0)
        {
            Console.WriteLine("No addresses found");
            return;
        }

        var socketAddresses = new SOCKET_ADDRESS[resolvedAddresses.Count];
        for (int i = 0; i < resolvedAddresses.Count; i++)
        {
            socketAddresses[i].iSockaddrLength = resolvedAddresses[i].Size;
            socketAddresses[i].lpSockaddr = resolvedAddresses[i].DangerousGetHandle();
        }

        NetApi32.SafeNetApiBuffer siteNames = null;

        var dsresult = DsAddressToSiteNames(dcname, (uint)socketAddresses.Length, socketAddresses, out siteNames);

        dsresult.ThrowIfFailed();

        if (siteNames == null || siteNames.IsInvalid)
        {
            Console.WriteLine("Sites were not found");
            return;
        }

        List<string> sites = siteNames.ToStringEnum(resolvedAddresses.Count).ToList();

        Console.WriteLine("Found sites {0} for addresses {1}", string.Join(", ", sites), string.Join(", ", ipAddresses));
    }
}

[ryannewington]

Another note, this seems to have been introduced in a recent version. Downgrading to 3.2.16 and the problem goes away.

[dahall]

Thank you for submitting such a thorough bug report! I'll have this resolved shortly.

[dahall]

@ryannewington When you say "compile your app", how are you referencing the Vanara.PInvoke.Ws2_32 assembly? As a NuGet package or by directly including the code in your build?

[ryannewington]

Hi David

That should say "compile my app". So this is using the NuGet package. If the sample app provided above, referencing the latest NuGet is compiled as x86 it works, x64 it fails.

I forked the library and modified the struct definition and could "fix" the issue by modifying the struct size.

[dahall]

The problem lies in the AnyCPU platform selected for all the NuGet packages. I'm investigating if NuGet will allow me to provide both an AnyCPU build and an x64 build. More coming shortly after some more research.

[ryannewington]

Oh right. I did notice that looking at the code of the version I downgraded to, there was no fixed size parameter on the struct. Is there an issue I should be aware of that adding the size fixed?

[dahall]

Yes. The 32-bit size and 64-bit size are different. I have a few structures in Vanara that are like this, so I need to find a solution. I'll close this with comments when I get it resolved. Unfortunately, the documentation on NuGet packaging is pretty weak.

[dahall]

Can you confirm that using v3.2.16 of the library has no problems even when compiling your exe under x64?

[dahall]

This is fixed with the latest commit. I'll publish soon.