signature: Make AuthorIdentity implement {Marshal,Unmarshal}Text (#92)

This makes it easier to e.g. put AuthorIdentity values in configuration
and API structs and have the values properly marshaled to/from string.

Since the type has grown we extracted it to a file of its own to keep
the clutter in verifier.go down.

signature/authoridentity.go

@@ -0,0 +1,66 @@
+// Copyright Axis Communications AB.
+//
+// For a full list of individual contributors, please see the commit history.
+//
+// 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 signature
+
+import (
+	"fmt"
+
+	"github.com/go-ldap/ldap"
+)
+
+// AuthorIdentity is a representation of the distinguished name
+// in the meta.security.authorIdentity field of an Eiffel event.
+// It can be compared to other values of the same type.
+type AuthorIdentity struct {
+	dn       *ldap.DN
+	original string
+}
+
+func NewAuthorIdentity(s string) (*AuthorIdentity, error) {
+	dn, err := ldap.ParseDN(s)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing author identity %q: %w", s, err)
+	}
+	return &AuthorIdentity{
+		dn:       dn,
+		original: s,
+	}, nil
+}
+
+// Equal returns true if the provided *AuthorIdentity is equal to this one,
+// igoring differences in whitespace etc.
+func (ai AuthorIdentity) Equal(other *AuthorIdentity) bool {
+	return ai.dn.Equal(other.dn)
+}
+
+func (ai AuthorIdentity) String() string {
+	return ai.original
+}
+
+func (ai AuthorIdentity) MarshalText() (text []byte, err error) {
+	return []byte(ai.original), nil
+}
+
+func (ai *AuthorIdentity) UnmarshalText(text []byte) error {
+	i, err := NewAuthorIdentity(string(text))
+	if err != nil {
+		return err
+	}
+	ai.dn = i.dn
+	ai.original = i.original
+	return nil
+}

signature/authoridentity_test.go

@@ -0,0 +1,33 @@
+// Copyright Axis Communications AB.
+//
+// For a full list of individual contributors, please see the commit history.
+//
+// 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 signature
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAuthorIdentity_UnmarshalText(t *testing.T) {
+	var data struct {
+		Identity *AuthorIdentity `json:"identity"`
+	}
+	require.NoError(t, json.Unmarshal([]byte(`{"identity": "CN=foo,DC=example,DC=com"}`), &data))
+	assert.Equal(t, "CN=foo,DC=example,DC=com", data.Identity.String())
+}

signature/verifier.go

@@ -27,7 +27,6 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/go-ldap/ldap"
 	"github.com/gowebpki/jcs"
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
@@ -44,35 +43,6 @@ type PublicKeyLocator interface {
 	Locate(ctx context.Context, identity *AuthorIdentity) ([]crypto.PublicKey, error)
 }
 
-// AuthorIdentity is a representation of the distinguished name
-// in the meta.security.authorIdentity field of an Eiffel event.
-// It can be compared to other values of the same type.
-type AuthorIdentity struct {
-	dn       *ldap.DN
-	original string
-}
-
-func NewAuthorIdentity(s string) (*AuthorIdentity, error) {
-	dn, err := ldap.ParseDN(s)
-	if err != nil {
-		return nil, fmt.Errorf("error parsing author identity %q: %w", s, err)
-	}
-	return &AuthorIdentity{
-		dn:       dn,
-		original: s,
-	}, nil
-}
-
-// Equal returns true if the provided *AuthorIdentity is equal to this one,
-// igoring differences in whitespace etc.
-func (ai *AuthorIdentity) Equal(other *AuthorIdentity) bool {
-	return ai.dn.Equal(other.dn)
-}
-
-func (ai *AuthorIdentity) String() string {
-	return ai.original
-}
-
 // Verifier can verify whether the signature of a given Eiffel event matches
 // any of the keys known by the associated PublicKeyLocator.
 type Verifier struct {