[Pcsclite-muscle] Client code review request

[David Woodhouse]

I would be grateful if someone could cast an eye over the code at
http://git.infradead.org/users/dwmw2/openconnect.git/commitdiff/c24046b93 which I have added to the OpenConnect VPN client for supporting TOTP/HOTP keys from a Yubikey NEO.

I wish client applications *didn't* have to get involved with
libpcsclite and specific hardware details — imagine what the world would
be like if we had to do the same for SSL keys, and PKCS#11/OpenSC didn't
exist. But this is at least a functional start.

Have I done the correct thing with the locking, using
SCardBeginTransaction and reselecting the applet each time? It seems to
make this code interoperate happily with OpenSC talking to the PIV
applet on the same device.

Is it a problem that I keep the card handle around for the entire
lifetime of the VPN session? I assume I'm preventing another
SCardConnect() from getting SCARD_SHARE_EXCLUSIVE access to the device
but should I *care* about that, enough to hook up some kind of "all
authentication is done now and you can call SCardReleaseContext()" event
sooner in the lifetime of the program? Using pcsc-spy it looks like
OpenSC is keeping *its* handle open, so I haven't bothered.

Are there TLV handling functions/macros that I should be using instead
of reinventing the wheel?

And what else have I done wrong that I *haven't* even thought about or
noticed? :)

Any constructive feedback would be gratefully received. Thanks.

-- 
dwmw2
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