digests.go

// Copyright 2021 Contributors to the Veraison project.
// SPDX-License-Identifier: Apache-2.0

package comid

import (
	"fmt"

	"github.com/veraison/swid"
)

// Digests is an alias for an array of SWID HashEntry
type Digests []swid.HashEntry

// NewDigests instantiates an empty array of Digests
func NewDigests() *Digests {
	return new(Digests)
}

// AddDigest create a new digest from the supplied arguments and appends it to
// the (already instantiated) Digests target.  The method is a no-op if it is
// invoked on a nil target and will refuse to add inconsistent algo/value
// combinations.
func (o *Digests) AddDigest(algID uint64, value []byte) *Digests {
	if o != nil {
		he := NewHashEntry(algID, value)
		if he == nil {
			return nil
		}
		*o = append(*o, *he)
	}
	return o
}

func (o Digests) Valid() error {
	for i, m := range o {
		if err := swid.ValidHashEntry(m.HashAlgID, m.HashValue); err != nil {
			return fmt.Errorf("digest at index %d: %w", i, err)
		}
	}
	return nil
}

func NewHashEntry(algID uint64, value []byte) *swid.HashEntry {
	var he swid.HashEntry

	err := he.Set(algID, value)
	if err != nil {
		return nil
	}

	return &he
}