Remove a bunch of input data checks now that byte buffers support
NULL data length pointers in order to be as transparent as possible.

Since PKCS#11 module initialization is done globally on the server side,
the real PKCS#11 modules check for initialization is made a no-op. The
only place it is possible to check for proper initialization by the
application is here - on the client side.

A number of PKCS#11 functions take a pointer to a buffer size as
argument. To be a transparent proxy of PKCS#11 calls, it is necessary to
support invoking these functions with a NULL pointer. pkcs11-proxy used
to send the buffer size as an integer and create a pointer to the integer
on the server side, but this is different to the backend PKCS#11 module
in some cases.

E.g. the C_Encrypt call is specified to have side effectes (finalizing)
when called with a NULL encrypted data length. The softhsm test suite
exposed that these side effects never occured because the NULL data length
pointer was conveyed as a valid pointer to the integer zero.

Since an additional uint8_t was added to "byte buffers", this is an
backwards incompatible change. As such, the version number in the protocol
greeting was increased (GCK_RPC_HANDSHAKE).

Passing size_t to _get_uint32 might leave garbage in top 32 bits of size_t
on 64 bits platforms. While initializing the size_t to 0 would probably
work, using a temporary uint32_t and casting that is more explicit IMO.

Since proto_write_attribute_array() happily writes arrays with len == 0,
we should probably parse them. Tounge in cheek.

This harmonizes with the softhsm test suite.

This matches the PKCS#11 specification better, and also matches
the test cases for softhsm.

SetPIN was using incorrect PIN length.

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>

Signed-off-by: Corentin Chary <cchary@commonit.com>

Will be needed to fix the WaitForSlotEvent issue

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>

Signed-off-by: Corentin Chary <cchary@commonit.com>

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>