go-libusb is deprecated and archived

[Jakuje]

The go-libusb library [1] used in yubihsm-connector is deprecated (and archived fork of [2]).

From packaging and security point of view, it is not a good idea to package archived fork of deprecated library.

Would it be possible to use the original version or "migrate" to the new gousb [3] that is alive and kicking?

I am not a go developer so I do not know what would it take to do so.

[1] https://github.com/thorduri/go-libusb [2] https://github.com/kylelemons/gousb [3] https://github.com/google/gousb

[QuLogic]

The conversion looks pretty straightforward to me. There are a few renames and there's no simple function like OpenEndpoint (you need to open a control, then an interface, then an endpoint). I also couldn't find an obvious way to do ReadTimeout/WriteTimeout.

Unfortunately, I don't any of this hardware, so I don't want to open a PR for something I can't test.

[QuLogic]

Please also note that the repository owner does not think anyone should use it (though now I'm thinking one of the contributors here probably opened that PR.)

[nevun]

We are aware of this and we are happy for any patches if you cannot wait for us to migrate.

[trebortech]

he conversion looks pretty straightforward to me. There are a few renames and there's no simple function like OpenEndpoint (you need to open a control, then an interface, then an endpoint). I also couldn't find an obvious way to do ReadTimeout/WriteTimeout.

Unfortunately, I don't any of this hardware, so I don't want to open a PR for something I can't test.

@QuLogic If you can provide the code updates in a gist I'll test on my hardware.

[QuLogic]

@trebortech feel free to try this branch: https://github.com/QuLogic/yubihsm-connector/tree/gousb

[syntaxcase]

@QuLogic I had some time to test your fork and I found two cases where it doesn't work correctly:

1. the ZLP is not sent anymore, you can test that with yubihsm-shell by executing plain echo 3 61. I did some digging and it's gousb that doesn't allow sending an empty buffer.
2. Errors out when resetting a device. If you run the tests in pytnon-yubihsm it will fail when the tests reset the device (don't run these tests on a production device!).

Regarding point 1, gousb doesn't even set LIBUSB_TRANSFER_ADD_ZERO_PACKET on xfer->flags (which only works on Linux btw) when calling libusb, so the ZLP can't be sent unless gousb is fixed. At least that's my impression from a quick look at gousb, are you aware of this limitation?

If these two points are resolved I would be happy to merge this.

[QuLogic]

OK, I guess that's what's done here, but I don't see LIBUSB_TRANSFER_ADD_ZERO_PACKET mentioned in thorduri/go-libusb either, so maybe it's something else.

[syntaxcase]

Yes, that's where the ZLP is sent.

Let me elaborate on LIBUSB_TRANSFER_ADD_ZERO_PACKET. Libusb can automatically send the ZLP if that flag is set in the xfer data structure. Since gousb does not allow sending an empty buffer, I went looking if it at least used that flag, but it doesn't. That's why I think it's an actual limitation in gousb. The thorduri/go-libusb library allows sending an empty buffer, so it has no need to use that flag. And by the way, setting LIBUSB_TRANSFER_ADD_ZERO_PACKET would not be enough in our case anyway, because it only works on Linux as far as I can see from the libusb code.

[QuLogic]

Maybe try removing this condition and see if it works?

[syntaxcase]

Yes, that's the condition that doesn't let the ZLP through; without it the plain echo works.