initial commit

tests/integration/oauth2_code_replay_prevention_test.go

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestOAuth2AuthorizationCodeReplayPrevention verifies that authorization codes
+// can only be used once. This is a critical security measure to prevent replay attacks
+// where an attacker intercepts an authorization code and attempts to use it multiple times,
+// as required by the OAuth 2.0 specification (RFC 6749).
+func TestOAuth2AuthorizationCodeReplayPrevention(t *testing.T) {
+	client := newTestClient(t)
+	appOwner := createTestAccount(t, client)
+	endUser := createTestAccount(t, client)
+
+	redirectURI := "https://example.com/callback"
+
+	t.Run("application authorization code can only be used once with client secret", func(t *testing.T) {
+		appID, _, _, clientSecret := createOAuth2Application(t, client, appOwner,
+			fmt.Sprintf("App %d", time.Now().UnixNano()),
+			[]string{redirectURI},
+			[]string{"identify"},
+		)
+
+		authCode, _ := authorizeOAuth2(t, client, endUser.Token, appID, redirectURI, []string{"identify"}, "", "", "")
+
+		token1 := exchangeOAuth2AuthorizationCode(t, client, appID, clientSecret, authCode, redirectURI, "")
+		if token1.AccessToken == "" {
+			t.Fatalf("first token exchange should succeed")
+		}
+
+		form := url.Values{
+			"grant_type":   {"authorization_code"},
+			"code":         {authCode},
+			"redirect_uri": {redirectURI},
+			"client_id":    {appID},
+		}
+
+		req, err := http.NewRequest(http.MethodPost, fmt.Sprintf("%s/oauth2/token", client.baseURL), strings.NewReader(form.Encode()))
+		if err != nil {
+			t.Fatalf("failed to build second token request: %v", err)
+		}
+		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+		req.SetBasicAuth(appID, clientSecret)
+		client.applyCommonHeaders(req)
+
+		resp, err := client.httpClient.Do(req)
+		if err != nil {
+			t.Fatalf("second token request failed: %v", err)
+		}
+		defer resp.Body.Close()
+
+		if resp.StatusCode == http.StatusOK {
+			t.Fatalf("authorization code should not be reusable - second exchange should fail")
+		}
+		if resp.StatusCode != http.StatusBadRequest && resp.StatusCode != http.StatusUnauthorized {
+			t.Fatalf("expected 400 or 401 for code replay, got %d: %s", resp.StatusCode, readResponseBody(resp))
+		}
+	})
+
+}