feat: add LoginEnabledGuard and RegistrationEnabledGuard

These guards check if the login or registration are enabled in the config. If so the guarded method is executed, if not the client will get the HTTP Error 400 Forbidden as an answer

Signed-off-by: Philip Molares <philip.molares@udo.edu>

src/api/utils/login-enabled.guard.ts

@@ -0,0 +1,33 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import {
+  BadRequestException,
+  CanActivate,
+  Inject,
+  Injectable,
+} from '@nestjs/common';
+
+import authConfiguration, { AuthConfig } from '../../config/auth.config';
+import { ConsoleLoggerService } from '../../logger/console-logger.service';
+
+@Injectable()
+export class LoginEnabledGuard implements CanActivate {
+  constructor(
+    private readonly logger: ConsoleLoggerService,
+    @Inject(authConfiguration.KEY)
+    private authConfig: AuthConfig,
+  ) {
+    this.logger.setContext(LoginEnabledGuard.name);
+  }
+
+  canActivate(): boolean {
+    if (!this.authConfig.local.enableLogin) {
+      this.logger.debug('Local auth is disabled.', 'canActivate');
+      throw new BadRequestException('Local auth is disabled.');
+    }
+    return true;
+  }
+}

src/api/utils/registration-enabled.guard.ts

@@ -0,0 +1,33 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import {
+  BadRequestException,
+  CanActivate,
+  Inject,
+  Injectable,
+} from '@nestjs/common';
+
+import authConfiguration, { AuthConfig } from '../../config/auth.config';
+import { ConsoleLoggerService } from '../../logger/console-logger.service';
+
+@Injectable()
+export class RegistrationEnabledGuard implements CanActivate {
+  constructor(
+    private readonly logger: ConsoleLoggerService,
+    @Inject(authConfiguration.KEY)
+    private authConfig: AuthConfig,
+  ) {
+    this.logger.setContext(RegistrationEnabledGuard.name);
+  }
+
+  canActivate(): boolean {
+    if (!this.authConfig.local.enableRegister) {
+      this.logger.debug('User registration is disabled.', 'canActivate');
+      throw new BadRequestException('User registration is disabled.');
+    }
+    return true;
+  }
+}