API Socket.SetRawSocketOption

[benaadams]

Currently the PAL layer blocks unknown options; eventually they may become adopted as enums, however prior to that it would be useful to be able to pass them through in an unvalidated manner.

public partial class Socket
{
 // existing: public void SetSocketOption(SocketOptionLevel optionLevel, SocketOptionName optionName, byte[] optionValue);
 public void SetRawSocketOption(int optionLevel, int optionName, ReadOnlySpan<byte> optionValue);

 // existing: public byte[] GetSocketOption(SocketOptionLevel optionLevel, SocketOptionName optionName, int optionLength);
 public int GetRawSocketOption(int optionLevel, int optionName, Span<byte> optionValue);
}

This has come up in https://github.com/dotnet/corefx/issues/16375 and also when trying to use TCP_CORK on Linux dotnet/aspnetcore#9603

/cc @stephentoub @geoffkizer

[benaadams]

Current workaround is to pinvoke e.g. on linux

[DllImport("libc")]
static unsafe extern int setsockopt(int sockfd, int level, int optname, void* optval, int optlen);

and then use setsockopt((int)socket.Handle, ....

[geoffkizer]

Presumably you would want GetRawSocketOption too?

[benaadams]

Yes :)

[wfurt]

and Bind() ? Can and Raw family would need them.

[wfurt]

cc: @krwq may be related to dotnet/corefx#35143

[los93sol]

Anyone had success using this workaround to set SO_ATTACH_FILTER? I've been trying to do it for several hours and keep getting back -1. Assuming it's because I'm attempting to build the bpf filter from structs and bypassing libpcap's pcap_compile method.

[karelz]

I would suggest to use SetPlatformOption name.

[krwq]

I do think this API is useful but I personally think we should not have this API in the framework since there is no way we can ever support this correctly on all platforms in uniform way. I'd prefer if someone wanting to set any options just did their own interop. Socket.Handle can be used to get native handle. I don't feel super strongly about this and it will be area owners final decision anyway :-)

[scalablecory]

@krwq why couldn't we support it? the support contract here is very minimal "we aren't managing platform for you, we just forward the params to interop layer".

[scalablecory]

Do we need unsafe here? How about span?

public partial class Socket
{
 public int SetRawSocketOption(int optionLevel, int optionName, ReadOnlySpan<byte> optionValue);
}

[benaadams]

How about span?

I'd be ok with that; updated summary

[scalablecory]

triage: not sure about naming, should we have GetRawSocketOption? ready for review.

also thinking about: RawBind