Implement text marshaling for ID/TrustDomain types (#180)

Signed-off-by: Andrew Harding <[email protected]>

v2/spiffeid/id.go

@@ -226,3 +226,27 @@ func (id ID) ReplaceSegments(segments ...string) (ID, error) {
 	id.path = path
 	return id, nil
 }
+
+// MarshalText returns a text representation of the ID. If the ID is the zero
+// value, nil is returned.
+func (id ID) MarshalText() ([]byte, error) {
+	if id.IsZero() {
+		return nil, nil
+	}
+	return []byte(id.String()), nil
+}
+
+// UnmarshalText decodes a text representation of the ID. If the text is empty,
+// the ID is set to the zero value.
+func (id *ID) UnmarshalText(text []byte) error {
+	if len(text) == 0 {
+		*id = ID{}
+		return nil
+	}
+	unmarshaled, err := FromString(string(text))
+	if err != nil {
+		return err
+	}
+	*id = unmarshaled
+	return nil
+}

v2/spiffeid/id_test.go

@@ -1,6 +1,7 @@
 package spiffeid_test
 
 import (
+	"encoding/json"
 	"fmt"
 	"net/url"
 	"testing"
@@ -426,6 +427,40 @@ func TestIDIsZero(t *testing.T) {
 	assert.False(t, td.ID().IsZero())
 }
 
+func TestIDTextMarshaler(t *testing.T) {
+	var s struct {
+		ID spiffeid.ID `json:"id"`
+	}
+
+	marshaled, err := json.Marshal(s)
+	require.NoError(t, err)
+	require.JSONEq(t, `{"id": ""}`, string(marshaled))
+
+	s.ID = spiffeid.RequireFromString("spiffe://trustdomain/path")
+
+	marshaled, err = json.Marshal(s)
+	require.NoError(t, err)
+	require.JSONEq(t, `{"id": "spiffe://trustdomain/path"}`, string(marshaled))
+}
+
+func TestIDTextUnmarshaler(t *testing.T) {
+	var s struct {
+		ID spiffeid.ID `json:"id"`
+	}
+
+	err := json.Unmarshal([]byte(`{"id": ""}`), &s)
+	require.NoError(t, err)
+	require.Zero(t, s.ID)
+
+	err = json.Unmarshal([]byte(`{"id": "BAD"}`), &s)
+	require.EqualError(t, err, "scheme is missing or invalid")
+	require.Zero(t, s.ID)
+
+	err = json.Unmarshal([]byte(`{"id": "spiffe://trustdomain/path"}`), &s)
+	require.NoError(t, err)
+	require.Equal(t, "spiffe://trustdomain/path", s.ID.String())
+}
+
 func assertIDEqual(t *testing.T, id spiffeid.ID, expectTD spiffeid.TrustDomain, expectPath string) {
 	assert.Equal(t, expectTD, id.TrustDomain(), "unexpected trust domain")
 	assert.Equal(t, expectPath, id.Path(), "unexpected path")

v2/spiffeid/trustdomain.go

@@ -81,6 +81,31 @@ func (td TrustDomain) Compare(other TrustDomain) int {
 	return strings.Compare(td.name, other.name)
 }
 
+// MarshalText returns a text representation of the trust domain. If the trust
+// domain is the zero value, nil is returned.
+func (td TrustDomain) MarshalText() ([]byte, error) {
+	if td.IsZero() {
+		return nil, nil
+	}
+	return []byte(td.String()), nil
+}
+
+// UnmarshalText decodes a text representation of the trust domain. If the text
+// is empty, the trust domain is set to the zero value.
+func (td *TrustDomain) UnmarshalText(text []byte) error {
+	if len(text) == 0 {
+		*td = TrustDomain{}
+		return nil
+	}
+
+	unmarshaled, err := TrustDomainFromString(string(text))
+	if err != nil {
+		return err
+	}
+	*td = unmarshaled
+	return nil
+}
+
 func isValidTrustDomainChar(c uint8) bool {
 	switch {
 	case c >= 'a' && c <= 'z':

v2/spiffeid/trustdomain_test.go

@@ -1,6 +1,7 @@
 package spiffeid_test
 
 import (
+	"encoding/json"
 	"fmt"
 	"net/url"
 	"testing"
@@ -131,3 +132,37 @@ func TestTrustDomainCompare(t *testing.T) {
 	assert.Equal(t, 0, a.Compare(a))
 	assert.Equal(t, 1, b.Compare(a))
 }
+
+func TestTrustDomainTextMarshaler(t *testing.T) {
+	var s struct {
+		TrustDomain spiffeid.TrustDomain `json:"trustDomain"`
+	}
+
+	marshaled, err := json.Marshal(s)
+	require.NoError(t, err)
+	require.JSONEq(t, `{"trustDomain": ""}`, string(marshaled))
+
+	s.TrustDomain = spiffeid.RequireTrustDomainFromString("trustdomain")
+
+	marshaled, err = json.Marshal(s)
+	require.NoError(t, err)
+	require.JSONEq(t, `{"trustDomain": "trustdomain"}`, string(marshaled))
+}
+
+func TestTrustDomainTextUnmarshaler(t *testing.T) {
+	var s struct {
+		TrustDomain spiffeid.TrustDomain `json:"trustDomain"`
+	}
+
+	err := json.Unmarshal([]byte(`{"trustDomain": ""}`), &s)
+	require.NoError(t, err)
+	require.Zero(t, s.TrustDomain)
+
+	err = json.Unmarshal([]byte(`{"trustDomain": "BAD"}`), &s)
+	require.EqualError(t, err, "trust domain characters are limited to lowercase letters, numbers, dots, dashes, and underscores")
+	require.Zero(t, s.TrustDomain)
+
+	err = json.Unmarshal([]byte(`{"trustDomain": "trustdomain"}`), &s)
+	require.NoError(t, err)
+	require.Equal(t, "trustdomain", s.TrustDomain.String())
+}