pcrs.go

// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package tspi

// #include <trousers/tss.h>
import "C"
import "unsafe"

// PCRs is a structure representing a PCR object and the PCR values
type PCRs struct {
	handle  C.TSS_HPCRS
	context C.TSS_HCONTEXT
	pcrs    [24][]byte
	pcrset  [24]bool
}

// SetPCRs takes an array of integers referring to PCRs. Any queries performed
// with this PCR object will then query these PCRs.
func (pcrs *PCRs) SetPCRs(pcrset []int) error {
	for pcr := range pcrs.pcrset {
		pcrs.pcrset[pcr] = false
	}
	for _, pcr := range pcrset {
		err := tspiError(C.Tspi_PcrComposite_SelectPcrIndex(pcrs.handle, (C.UINT32)(pcr)))
		if err != nil {
			return err
		}
		pcrs.pcrset[pcr] = true
	}
	return nil
}

// GetPCRValues obtains the PCR values for any PCRs that have been set.
func (pcrs *PCRs) GetPCRValues() ([][]byte, error) {
	var buflen C.UINT32
	var buf *C.BYTE
	for pcr := range pcrs.pcrs {
		if pcrs.pcrset[pcr] == false {
			continue
		}
		err := tspiError(C.Tspi_PcrComposite_GetPcrValue(pcrs.handle, (C.UINT32)(pcr), &buflen, &buf))
		if err != nil {
			return nil, err
		}
		pcrs.pcrs[pcr] = C.GoBytes(unsafe.Pointer(buf), (C.int)(buflen))
		C.Tspi_Context_FreeMemory(pcrs.context, buf)
	}
	return pcrs.pcrs[:], nil
}