fix(repository): Move backend code into subdirectory

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

backend/src/auth/token.strategy.ts

@@ -0,0 +1,36 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { Injectable, UnauthorizedException } from '@nestjs/common';
+import { AuthGuard, PassportStrategy } from '@nestjs/passport';
+import { Strategy } from 'passport-http-bearer';
+
+import { NotInDBError, TokenNotValidError } from '../errors/errors';
+import { User } from '../users/user.entity';
+import { AuthService } from './auth.service';
+
+@Injectable()
+export class TokenAuthGuard extends AuthGuard('token') {}
+
+@Injectable()
+export class TokenStrategy extends PassportStrategy(Strategy, 'token') {
+  constructor(private authService: AuthService) {
+    super();
+  }
+
+  async validate(token: string): Promise<User> {
+    try {
+      return await this.authService.validateToken(token);
+    } catch (error) {
+      if (
+        error instanceof NotInDBError ||
+        error instanceof TokenNotValidError
+      ) {
+        throw new UnauthorizedException(error.message);
+      }
+      throw error;
+    }
+  }
+}