fix bytes & string protocol

interface.go

@@ -9,5 +9,7 @@ type Manager interface {
 
 type Vault interface {
 	Keys() []string
-	Get(key string) ([]byte, bool)
+	GetRaw(key string) ([]byte, bool)
+	GetBytes(key string) ([]byte, error)
+	GetString(key string) (string, error)
 }

vault.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/golang/protobuf/proto"
 	"golang.org/x/exp/maps"
+	"google.golang.org/protobuf/encoding/protowire"
 )
 
 type vault map[string][]byte
@@ -16,11 +17,33 @@ func (v vault) Keys() []string {
 	return maps.Keys(v)
 }
 
-func (v vault) Get(key string) ([]byte, bool) {
+func (v vault) GetRaw(key string) ([]byte, bool) {
 	val, ok := v[key]
 	return val, ok
 }
 
+func (v vault) GetBytes(key string) ([]byte, error) {
+	raw, ok := v[key]
+	if !ok {
+		return nil, fmt.Errorf("key not found: %s", key)
+	}
+
+	val, n := protowire.ConsumeBytes(raw)
+	if n < 0 {
+		return nil, fmt.Errorf("invalid protobuf bytes")
+	}
+
+	return val, nil
+}
+
+func (v vault) GetString(key string) (string, error) {
+	val, err := v.GetBytes(key)
+	if err != nil {
+		return "", err
+	}
+	return string(val), nil
+}
+
 // metadata is optional. but if it exists, validate with it.
 func loadVault(src io.Reader, m *metadata) (Vault, error) {
 	fileSizeBuf := make([]byte, 4)

vault_test.go

@@ -17,10 +17,10 @@ func Test_loadVault(t *testing.T) {
 
 	assert.Equal(t, 2, len(v.Keys()))
 
-	val, ok := v.Get("world")
+	val, err := v.GetString("world")
-	assert.Equal(t, "hello", string(val))
+	assert.Equal(t, "hello", val)
-	assert.True(t, ok)
+	assert.NoError(t, err)
 
-	val, ok = v.Get("foo")
+	_, err = v.GetBytes("foo")
-	assert.False(t, ok)
+	assert.Error(t, err)
 }