fix: do not modify userInfo when marshaling

pkg/oidc/introspection_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"testing"
 
+	"github.com/muhlemmer/gu"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -25,7 +26,7 @@ func TestIntrospectionResponse_SetUserInfo(t *testing.T) {
 				UserInfoProfile: userInfoData.UserInfoProfile,
 				UserInfoEmail:   userInfoData.UserInfoEmail,
 				UserInfoPhone:   userInfoData.UserInfoPhone,
-				Claims:          userInfoData.Claims,
+				Claims:          gu.MapCopy(userInfoData.Claims),
 			},
 		},
 		{

pkg/oidc/regression_assert_test.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"io"
 	"os"
+	"reflect"
 	"strings"
 	"testing"
 
@@ -38,10 +39,12 @@ func Test_assert_regression(t *testing.T) {
 
 			assert.JSONEq(t, want, first)
 
+			target := reflect.New(reflect.TypeOf(obj).Elem()).Interface()
+
 			require.NoError(t,
-				json.Unmarshal([]byte(first), obj),
+				json.Unmarshal([]byte(first), target),
 			)
-			second, err := json.Marshal(obj)
+			second, err := json.Marshal(target)
 			require.NoError(t, err)
 
 			assert.JSONEq(t, want, string(second))

pkg/oidc/token.go

@@ -158,7 +158,6 @@ func (t *IDTokenClaims) SetUserInfo(i *UserInfo) {
 	t.UserInfoEmail = i.UserInfoEmail
 	t.UserInfoPhone = i.UserInfoPhone
 	t.Address = i.Address
-
 	if t.Claims == nil {
 		t.Claims = make(map[string]any, len(t.Claims))
 	}

pkg/oidc/token_test.go

@@ -4,7 +4,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/muhlemmer/gu"
 	"github.com/stretchr/testify/assert"
 	"golang.org/x/text/language"
 	"gopkg.in/square/go-jose.v2"
@@ -182,7 +181,9 @@ func TestIDTokenClaims_SetUserInfo(t *testing.T) {
 		UserInfoEmail:   userInfoData.UserInfoEmail,
 		UserInfoPhone:   userInfoData.UserInfoPhone,
 		Address:         userInfoData.Address,
-		Claims:          gu.MapCopy(userInfoData.Claims),
+		Claims: map[string]interface{}{
+			"foo": "bar",
+		},
 	}
 
 	var got IDTokenClaims

pkg/oidc/userinfo_test.go

@@ -52,11 +52,14 @@ func TestUserInfoMarshal(t *testing.T) {
 
 	out := new(UserInfo)
 	assert.NoError(t, json.Unmarshal(marshal, out))
-	assert.Equal(t, userinfo, out)
 	expected, err := json.Marshal(out)
 
 	assert.NoError(t, err)
 	assert.Equal(t, expected, marshal)
+
+	out2 := new(UserInfo)
+	assert.NoError(t, json.Unmarshal(expected, out2))
+	assert.Equal(t, out, out2)
 }
 
 func TestUserInfoEmailVerifiedUnmarshal(t *testing.T) {

pkg/oidc/util.go

@@ -9,7 +9,7 @@ import (
 // mergeAndMarshalClaims merges registered and the custom
 // claims map into a single JSON object.
 // Registered fields overwrite custom claims.
-func mergeAndMarshalClaims(registered any, claims map[string]any) ([]byte, error) {
+func mergeAndMarshalClaims(registered any, extraClaims map[string]any) ([]byte, error) {
 	// Use a buffer for memory re-use, instead off letting
 	// json allocate a new []byte for every step.
 	buf := new(bytes.Buffer)
@@ -19,16 +19,21 @@ func mergeAndMarshalClaims(registered any, claims map[string]any) ([]byte, error
 		return nil, fmt.Errorf("oidc registered claims: %w", err)
 	}
 
-	if len(claims) > 0 {
+	if len(extraClaims) > 0 {
+		merged := make(map[string]any)
+		for k, v := range extraClaims {
+			merged[k] = v
+		}
+
 		// Merge JSON data into custom claims.
 		// The full-read action by the decoder resets the buffer
 		// to zero len, while retaining underlaying cap.
-		if err := json.NewDecoder(buf).Decode(&claims); err != nil {
+		if err := json.NewDecoder(buf).Decode(&merged); err != nil {
 			return nil, fmt.Errorf("oidc registered claims: %w", err)
 		}
 
 		// Marshal the final result.
-		if err := json.NewEncoder(buf).Encode(claims); err != nil {
+		if err := json.NewEncoder(buf).Encode(merged); err != nil {
 			return nil, fmt.Errorf("oidc custom claims: %w", err)
 		}
 	}