feat(auth): add OAuth2 login (#276)

* feat(auth): add OAuth2 login with GitHub and Google

* chore(translations): add files for Japanese

* fix(auth): fix link function for GitHub

* feat(oauth): basic oidc implementation

* feat(oauth): oauth guard

* fix: disable image optimizations for logo to prevent caching issues with custom logos

* fix: memory leak while downloading large files

* chore(translations): update translations via Crowdin (#278)

* New translations en-us.ts (Japanese)

* New translations en-us.ts (Japanese)

* New translations en-us.ts (Japanese)

* release: 0.18.2

* doc(translations): Add Japanese README (#279)

* Added Japanese README.

* Added JAPANESE README link to README.md.

* Updated Japanese README.

* Updated Environment Variable Table.

* updated zh-cn README.

* feat(oauth): unlink account

* refactor(oauth): make providers extensible

* fix(oauth): fix discoveryUri error when toggle google-enabled

* feat(oauth): add microsoft and discord as oauth provider

* docs(oauth): update README.md

* docs(oauth): update oauth2-guide.md

* set password to null for new oauth users

* New translations en-us.ts (Japanese) (#281)

* chore(translations): add Polish files

* fix(oauth): fix random username and password

* feat(oauth): add totp

* fix(oauth): fix totp throttle

* fix(oauth): fix qrcode and remove comment

* feat(oauth): add error page

* fix(oauth): i18n of error page

* feat(auth): add OAuth2 login

* fix(auth): fix link function for GitHub

* feat(oauth): basic oidc implementation

* feat(oauth): oauth guard

* feat(oauth): unlink account

* refactor(oauth): make providers extensible

* fix(oauth): fix discoveryUri error when toggle google-enabled

* feat(oauth): add microsoft and discord as oauth provider

* docs(oauth): update README.md

* docs(oauth): update oauth2-guide.md

* set password to null for new oauth users

* fix(oauth): fix random username and password

* feat(oauth): add totp

* fix(oauth): fix totp throttle

* fix(oauth): fix qrcode and remove comment

* feat(oauth): add error page

* fix(oauth): i18n of error page

* refactor: return null instead of `false` in `getIdOfCurrentUser` functiom

* feat: show original oauth error if available

* refactor: run formatter

* refactor(oauth): error message i18n

* refactor(oauth): make OAuth token available
someone may use it (to revoke token or get other info etc.)
also improved the i18n message

* chore(oauth): remove unused import

* chore: add database migration

* fix: missing python installation for nanoid

---------

Co-authored-by: Elias Schneider <login@eliasschneider.com>
Co-authored-by: ふうせん <10260662+fusengum@users.noreply.github.com>

backend/src/app.module.ts

@@ -15,6 +15,8 @@ import { UserModule } from "./user/user.module";
 import { ClamScanModule } from "./clamscan/clamscan.module";
 import { ReverseShareModule } from "./reverseShare/reverseShare.module";
 import { AppController } from "./app.controller";
+import { OAuthModule } from "./oauth/oauth.module";
+import { CacheModule } from "@nestjs/cache-manager";
 
 @Module({
   imports: [
@@ -33,10 +35,12 @@ import { AppController } from "./app.controller";
     ScheduleModule.forRoot(),
     ClamScanModule,
     ReverseShareModule,
+    OAuthModule,
+    CacheModule.register({
+      isGlobal: true,
+    }),
   ],
-  controllers:[
-    AppController,
-  ],
+  controllers: [AppController],
   providers: [
     {
       provide: APP_GUARD,

backend/src/auth/auth.controller.ts

@@ -47,7 +47,7 @@ export class AuthController {
 
     const result = await this.authService.signUp(dto);
 
-    response = this.addTokensToResponse(
+    this.authService.addTokensToResponse(
       response,
       result.refreshToken,
       result.accessToken,
@@ -66,7 +66,7 @@ export class AuthController {
     const result = await this.authService.signIn(dto);
 
     if (result.accessToken && result.refreshToken) {
-      response = this.addTokensToResponse(
+      this.authService.addTokensToResponse(
         response,
         result.refreshToken,
         result.accessToken,
@@ -85,7 +85,7 @@ export class AuthController {
   ) {
     const result = await this.authTotpService.signInTotp(dto);
 
-    response = this.addTokensToResponse(
+    this.authService.addTokensToResponse(
       response,
       result.refreshToken,
       result.accessToken,
@@ -117,11 +117,11 @@ export class AuthController {
   ) {
     const result = await this.authService.updatePassword(
       user,
-      dto.oldPassword,
       dto.password,
+      dto.oldPassword,
     );
 
-    response = this.addTokensToResponse(response, result.refreshToken);
+    this.authService.addTokensToResponse(response, result.refreshToken);
     return new TokenDTO().from(result);
   }
 
@@ -136,7 +136,7 @@ export class AuthController {
     const accessToken = await this.authService.refreshAccessToken(
       request.cookies.refresh_token,
     );
-    response = this.addTokensToResponse(response, undefined, accessToken);
+    this.authService.addTokensToResponse(response, undefined, accessToken);
     return new TokenDTO().from({ accessToken });
   }
 
@@ -172,22 +172,4 @@ export class AuthController {
     // Note: We use VerifyTotpDTO here because it has both fields we need: password and totp code
     return this.authTotpService.disableTotp(user, body.password, body.code);
   }
-
-  private addTokensToResponse(
-    response: Response,
-    refreshToken?: string,
-    accessToken?: string,
-  ) {
-    if (accessToken)
-      response.cookie("access_token", accessToken, { sameSite: "lax" });
-    if (refreshToken)
-      response.cookie("refresh_token", refreshToken, {
-        path: "/api/auth/token",
-        httpOnly: true,
-        sameSite: "strict",
-        maxAge: 1000 * 60 * 60 * 24 * 30 * 3,
-      });
-
-    return response;
-  }
 }

backend/src/auth/auth.module.ts

@@ -7,7 +7,12 @@ import { AuthTotpService } from "./authTotp.service";
 import { JwtStrategy } from "./strategy/jwt.strategy";
 
 @Module({
-  imports: [JwtModule.register({}), EmailModule],
+  imports: [
+    JwtModule.register({
+      global: true,
+    }),
+    EmailModule,
+  ],
   controllers: [AuthController],
   providers: [AuthService, AuthTotpService, JwtStrategy],
   exports: [AuthService],

backend/src/auth/auth.service.ts

@@ -8,6 +8,7 @@ import { JwtService } from "@nestjs/jwt";
 import { User } from "@prisma/client";
 import { PrismaClientKnownRequestError } from "@prisma/client/runtime/library";
 import * as argon from "argon2";
+import { Request, Response } from "express";
 import * as moment from "moment";
 import { ConfigService } from "src/config/config.service";
 import { EmailService } from "src/email/email.service";
@@ -27,7 +28,7 @@ export class AuthService {
   async signUp(dto: AuthRegisterDTO) {
     const isFirstUser = (await this.prisma.user.count()) == 0;
 
-    const hash = await argon.hash(dto.password);
+    const hash = dto.password ? await argon.hash(dto.password) : null;
     try {
       const user = await this.prisma.user.create({
         data: {
@@ -43,7 +44,7 @@ export class AuthService {
       );
       const accessToken = await this.createAccessToken(user, refreshTokenId);
 
-      return { accessToken, refreshToken };
+      return { accessToken, refreshToken, user };
     } catch (e) {
       if (e instanceof PrismaClientKnownRequestError) {
         if (e.code == "P2002") {
@@ -69,9 +70,16 @@ export class AuthService {
     if (!user || !(await argon.verify(user.password, dto.password)))
       throw new UnauthorizedException("Wrong email or password");
 
+    return this.generateToken(user);
+  }
+
+  async generateToken(user: User, isOAuth = false) {
     // TODO: Make all old loginTokens invalid when a new one is created
     // Check if the user has TOTP enabled
-    if (user.totpVerified) {
+    if (
+      user.totpVerified &&
+      !(isOAuth && this.config.get("oauth.ignoreTotp"))
+    ) {
       const loginToken = await this.createLoginToken(user.id);
 
       return { loginToken };
@@ -129,9 +137,11 @@ export class AuthService {
     });
   }
 
-  async updatePassword(user: User, oldPassword: string, newPassword: string) {
-    if (!(await argon.verify(user.password, oldPassword)))
-      throw new ForbiddenException("Invalid password");
+  async updatePassword(user: User, newPassword: string, oldPassword?: string) {
+    const isPasswordValid =
+      !user.password || !(await argon.verify(user.password, oldPassword));
+
+    if (!isPasswordValid) throw new ForbiddenException("Invalid password");
 
     const hash = await argon.hash(newPassword);
 
@@ -210,4 +220,38 @@ export class AuthService {
 
     return loginToken;
   }
+
+  addTokensToResponse(
+    response: Response,
+    refreshToken?: string,
+    accessToken?: string,
+  ) {
+    if (accessToken)
+      response.cookie("access_token", accessToken, { sameSite: "lax" });
+    if (refreshToken)
+      response.cookie("refresh_token", refreshToken, {
+        path: "/api/auth/token",
+        httpOnly: true,
+        sameSite: "strict",
+        maxAge: 1000 * 60 * 60 * 24 * 30 * 3,
+      });
+  }
+
+  /**
+   * Returns the user id if the user is logged in, null otherwise
+   */
+  async getIdOfCurrentUser(request: Request): Promise<string | null> {
+    if (!request.cookies.access_token) return null;
+    try {
+      const payload = await this.jwtService.verifyAsync(
+        request.cookies.access_token,
+        {
+          secret: this.config.get("internal.jwtSecret"),
+        },
+      );
+      return payload.sub;
+    } catch {
+      return null;
+    }
+  }
 }

backend/src/auth/authTotp.service.ts

@@ -22,43 +22,29 @@ export class AuthTotpService {
   ) {}
 
   async signInTotp(dto: AuthSignInTotpDTO) {
-    if (!dto.email && !dto.username)
-      throw new BadRequestException("Email or username is required");
-
-    const user = await this.prisma.user.findFirst({
-      where: {
-        OR: [{ email: dto.email }, { username: dto.username }],
-      },
-    });
-
-    if (!user || !(await argon.verify(user.password, dto.password)))
-      throw new UnauthorizedException("Wrong email or password");
-
     const token = await this.prisma.loginToken.findFirst({
       where: {
         token: dto.loginToken,
       },
+      include: {
+        user: true,
+      },
     });
 
-    if (!token || token.userId != user.id || token.used)
+    if (!token || token.used)
       throw new UnauthorizedException("Invalid login token");
 
     if (token.expiresAt < new Date())
       throw new UnauthorizedException("Login token expired", "token_expired");
 
     // Check the TOTP code
-    const { totpSecret } = await this.prisma.user.findUnique({
-      where: { id: user.id },
-      select: { totpSecret: true },
-    });
+    const { totpSecret } = token.user;
 
     if (!totpSecret) {
       throw new BadRequestException("TOTP is not enabled");
     }
 
-    const expected = authenticator.generate(totpSecret);
-
-    if (dto.totp !== expected) {
+    if (!authenticator.check(dto.totp, totpSecret)) {
       throw new BadRequestException("Invalid code");
     }
 
@@ -69,9 +55,9 @@ export class AuthTotpService {
     });
 
     const { refreshToken, refreshTokenId } =
-      await this.authService.createRefreshToken(user.id);
+      await this.authService.createRefreshToken(token.user.id);
     const accessToken = await this.authService.createAccessToken(
-      user,
+      token.user,
       refreshTokenId,
     );
 

backend/src/auth/dto/authSignInTotp.dto.ts

@@ -1,7 +1,7 @@
 import { IsString } from "class-validator";
 import { AuthSignInDTO } from "./authSignIn.dto";
 
-export class AuthSignInTotpDTO extends AuthSignInDTO {
+export class AuthSignInTotpDTO {
   @IsString()
   totp: string;
 

backend/src/auth/dto/updatePassword.dto.ts

@@ -1,8 +1,9 @@
 import { PickType } from "@nestjs/swagger";
-import { IsString } from "class-validator";
+import { IsOptional, IsString } from "class-validator";
 import { UserDTO } from "src/user/dto/user.dto";
 
 export class UpdatePasswordDTO extends PickType(UserDTO, ["password"]) {
   @IsString()
-  oldPassword: string;
+  @IsOptional()
+  oldPassword?: string;
 }

backend/src/config/config.service.ts

@@ -6,13 +6,20 @@ import {
 } from "@nestjs/common";
 import { Config } from "@prisma/client";
 import { PrismaService } from "src/prisma/prisma.service";
+import { EventEmitter } from "events";
 
+/**
+ * ConfigService extends EventEmitter to allow listening for config updates,
+ * now only `update` event will be emitted.
+ */
 @Injectable()
-export class ConfigService {
+export class ConfigService extends EventEmitter {
   constructor(
     @Inject("CONFIG_VARIABLES") private configVariables: Config[],
     private prisma: PrismaService,
-  ) {}
+  ) {
+    super();
+  }
 
   get(key: `${string}.${string}`): any {
     const configVariable = this.configVariables.filter(
@@ -105,6 +112,8 @@ export class ConfigService {
 
     this.configVariables = await this.prisma.config.findMany();
 
+    this.emit("update", key, value);
+
     return updatedVariable;
   }
 }

backend/src/config/logo.service.ts

@@ -26,7 +26,7 @@ export class LogoService {
       fs.promises.writeFile(
         `${IMAGES_PATH}/icons/icon-${size}x${size}.png`,
         resized,
-        "binary"
+        "binary",
       );
     }
   }

backend/src/oauth/dto/oauthCallback.dto.ts

@@ -0,0 +1,9 @@
+import { IsString } from "class-validator";
+
+export class OAuthCallbackDto {
+  @IsString()
+  code: string;
+
+  @IsString()
+  state: string;
+}

backend/src/oauth/dto/oauthSignIn.dto.ts

@@ -0,0 +1,6 @@
+export interface OAuthSignInDto {
+  provider: "github" | "google" | "microsoft" | "discord" | "oidc";
+  providerId: string;
+  providerUsername: string;
+  email: string;
+}

backend/src/oauth/exceptions/errorPage.exception.ts

@@ -0,0 +1,15 @@
+export class ErrorPageException extends Error {
+  /**
+   * Exception for redirecting to error page (all i18n key should omit `error.msg` and `error.param` prefix)
+   * @param key i18n key of message
+   * @param redirect redirect url
+   * @param params message params (key)
+   */
+  constructor(
+    public readonly key: string = "default",
+    public readonly redirect: string = "/",
+    public readonly params?: string[],
+  ) {
+    super("error");
+  }
+}

backend/src/oauth/filter/errorPageException.filter.ts

@@ -0,0 +1,22 @@
+import { ArgumentsHost, Catch, ExceptionFilter } from "@nestjs/common";
+import { ConfigService } from "../../config/config.service";
+import { ErrorPageException } from "../exceptions/errorPage.exception";
+
+@Catch(ErrorPageException)
+export class ErrorPageExceptionFilter implements ExceptionFilter {
+  constructor(private config: ConfigService) {}
+
+  catch(exception: ErrorPageException, host: ArgumentsHost) {
+    const ctx = host.switchToHttp();
+    const response = ctx.getResponse();
+
+    const url = new URL(`${this.config.get("general.appUrl")}/error`);
+    url.searchParams.set("redirect", exception.redirect);
+    url.searchParams.set("error", exception.key);
+    if (exception.params) {
+      url.searchParams.set("params", exception.params.join(","));
+    }
+
+    response.redirect(url.toString());
+  }
+}

backend/src/oauth/filter/oauthException.filter.ts

@@ -0,0 +1,31 @@
+import {
+  ArgumentsHost,
+  Catch,
+  ExceptionFilter,
+  HttpException,
+} from "@nestjs/common";
+import { ConfigService } from "../../config/config.service";
+
+@Catch(HttpException)
+export class OAuthExceptionFilter implements ExceptionFilter {
+  private errorKeys: Record<string, string> = {
+    access_denied: "access_denied",
+    expired_token: "expired_token",
+  };
+
+  constructor(private config: ConfigService) {}
+
+  catch(_exception: HttpException, host: ArgumentsHost) {
+    const ctx = host.switchToHttp();
+    const response = ctx.getResponse();
+    const request = ctx.getRequest();
+
+    const key = this.errorKeys[request.query.error] || "default";
+
+    const url = new URL(`${this.config.get("general.appUrl")}/error`);
+    url.searchParams.set("redirect", "/account");
+    url.searchParams.set("error", key);
+
+    response.redirect(url.toString());
+  }
+}

backend/src/oauth/guard/oauth.guard.ts

@@ -0,0 +1,12 @@
+import { CanActivate, ExecutionContext, Injectable } from "@nestjs/common";
+
+@Injectable()
+export class OAuthGuard implements CanActivate {
+  constructor() {}
+
+  canActivate(context: ExecutionContext): boolean {
+    const request = context.switchToHttp().getRequest();
+    const provider = request.params.provider;
+    return request.query.state === request.cookies[`oauth_${provider}_state`];
+  }
+}

backend/src/oauth/guard/provider.guard.ts

@@ -0,0 +1,24 @@
+import {
+  CanActivate,
+  ExecutionContext,
+  Inject,
+  Injectable,
+} from "@nestjs/common";
+import { ConfigService } from "../../config/config.service";
+
+@Injectable()
+export class ProviderGuard implements CanActivate {
+  constructor(
+    private config: ConfigService,
+    @Inject("OAUTH_PLATFORMS") private platforms: string[],
+  ) {}
+
+  canActivate(context: ExecutionContext): boolean {
+    const request = context.switchToHttp().getRequest();
+    const provider = request.params.provider;
+    return (
+      this.platforms.includes(provider) &&
+      this.config.get(`oauth.${provider}-enabled`)
+    );
+  }
+}

backend/src/oauth/oauth.controller.ts

@@ -0,0 +1,110 @@
+import {
+  Controller,
+  Get,
+  Inject,
+  Param,
+  Post,
+  Query,
+  Req,
+  Res,
+  UseFilters,
+  UseGuards,
+} from "@nestjs/common";
+import { User } from "@prisma/client";
+import { Request, Response } from "express";
+import { nanoid } from "nanoid";
+import { AuthService } from "../auth/auth.service";
+import { GetUser } from "../auth/decorator/getUser.decorator";
+import { JwtGuard } from "../auth/guard/jwt.guard";
+import { ConfigService } from "../config/config.service";
+import { OAuthCallbackDto } from "./dto/oauthCallback.dto";
+import { ErrorPageExceptionFilter } from "./filter/errorPageException.filter";
+import { OAuthGuard } from "./guard/oauth.guard";
+import { ProviderGuard } from "./guard/provider.guard";
+import { OAuthService } from "./oauth.service";
+import { OAuthProvider } from "./provider/oauthProvider.interface";
+import { OAuthExceptionFilter } from "./filter/oauthException.filter";
+
+@Controller("oauth")
+export class OAuthController {
+  constructor(
+    private authService: AuthService,
+    private oauthService: OAuthService,
+    private config: ConfigService,
+    @Inject("OAUTH_PROVIDERS")
+    private providers: Record<string, OAuthProvider<unknown>>,
+  ) {}
+
+  @Get("available")
+  available() {
+    return this.oauthService.available();
+  }
+
+  @Get("status")
+  @UseGuards(JwtGuard)
+  async status(@GetUser() user: User) {
+    return this.oauthService.status(user);
+  }
+
+  @Get("auth/:provider")
+  @UseGuards(ProviderGuard)
+  @UseFilters(ErrorPageExceptionFilter)
+  async auth(
+    @Param("provider") provider: string,
+    @Res({ passthrough: true }) response: Response,
+  ) {
+    const state = nanoid(16);
+    const url = await this.providers[provider].getAuthEndpoint(state);
+    response.cookie(`oauth_${provider}_state`, state, { sameSite: "lax" });
+    response.redirect(url);
+  }
+
+  @Get("callback/:provider")
+  @UseGuards(ProviderGuard, OAuthGuard)
+  @UseFilters(ErrorPageExceptionFilter, OAuthExceptionFilter)
+  async callback(
+    @Param("provider") provider: string,
+    @Query() query: OAuthCallbackDto,
+    @Req() request: Request,
+    @Res({ passthrough: true }) response: Response,
+  ) {
+    const oauthToken = await this.providers[provider].getToken(query);
+    const user = await this.providers[provider].getUserInfo(oauthToken, query);
+    const id = await this.authService.getIdOfCurrentUser(request);
+
+    if (id) {
+      await this.oauthService.link(
+        id,
+        provider,
+        user.providerId,
+        user.providerUsername,
+      );
+      response.redirect(this.config.get("general.appUrl") + "/account");
+    } else {
+      const token: {
+        accessToken?: string;
+        refreshToken?: string;
+        loginToken?: string;
+      } = await this.oauthService.signIn(user);
+      if (token.accessToken) {
+        this.authService.addTokensToResponse(
+          response,
+          token.refreshToken,
+          token.accessToken,
+        );
+        response.redirect(this.config.get("general.appUrl"));
+      } else {
+        response.redirect(
+          this.config.get("general.appUrl") + `/auth/totp/${token.loginToken}`,
+        );
+      }
+    }
+  }
+
+  @Post("unlink/:provider")
+  @UseGuards(JwtGuard, ProviderGuard)
+  @UseFilters(ErrorPageExceptionFilter)
+  unlink(@GetUser() user: User, @Param("provider") provider: string) {
+    return this.oauthService.unlink(user, provider);
+  }
+}

backend/src/oauth/oauth.module.ts

@@ -0,0 +1,56 @@
+import { Module } from "@nestjs/common";
+import { OAuthController } from "./oauth.controller";
+import { OAuthService } from "./oauth.service";
+import { AuthModule } from "../auth/auth.module";
+import { GitHubProvider } from "./provider/github.provider";
+import { GoogleProvider } from "./provider/google.provider";
+import { OAuthProvider } from "./provider/oauthProvider.interface";
+import { OidcProvider } from "./provider/oidc.provider";
+import { DiscordProvider } from "./provider/discord.provider";
+import { MicrosoftProvider } from "./provider/microsoft.provider";
+
+@Module({
+  controllers: [OAuthController],
+  providers: [
+    OAuthService,
+    GitHubProvider,
+    GoogleProvider,
+    MicrosoftProvider,
+    DiscordProvider,
+    OidcProvider,
+    {
+      provide: "OAUTH_PROVIDERS",
+      useFactory(
+        github: GitHubProvider,
+        google: GoogleProvider,
+        microsoft: MicrosoftProvider,
+        discord: DiscordProvider,
+        oidc: OidcProvider,
+      ): Record<string, OAuthProvider<unknown>> {
+        return {
+          github,
+          google,
+          microsoft,
+          discord,
+          oidc,
+        };
+      },
+      inject: [
+        GitHubProvider,
+        GoogleProvider,
+        MicrosoftProvider,
+        DiscordProvider,
+        OidcProvider,
+      ],
+    },
+    {
+      provide: "OAUTH_PLATFORMS",
+      useFactory(providers: Record<string, OAuthProvider<unknown>>): string[] {
+        return Object.keys(providers);
+      },
+      inject: ["OAUTH_PROVIDERS"],
+    },
+  ],
+  imports: [AuthModule],
+})
+export class OAuthModule {}

backend/src/oauth/oauth.service.ts

@@ -0,0 +1,171 @@
+import { Inject, Injectable } from "@nestjs/common";
+import { User } from "@prisma/client";
+import { nanoid } from "nanoid";
+import { AuthService } from "../auth/auth.service";
+import { ConfigService } from "../config/config.service";
+import { PrismaService } from "../prisma/prisma.service";
+import { OAuthSignInDto } from "./dto/oauthSignIn.dto";
+import { ErrorPageException } from "./exceptions/errorPage.exception";
+
+@Injectable()
+export class OAuthService {
+  constructor(
+    private prisma: PrismaService,
+    private config: ConfigService,
+    private auth: AuthService,
+    @Inject("OAUTH_PLATFORMS") private platforms: string[],
+  ) {}
+
+  available(): string[] {
+    return this.platforms
+      .map((platform) => [
+        platform,
+        this.config.get(`oauth.${platform}-enabled`),
+      ])
+      .filter(([_, enabled]) => enabled)
+      .map(([platform, _]) => platform);
+  }
+
+  async status(user: User) {
+    const oauthUsers = await this.prisma.oAuthUser.findMany({
+      select: {
+        provider: true,
+        providerUsername: true,
+      },
+      where: {
+        userId: user.id,
+      },
+    });
+    return Object.fromEntries(oauthUsers.map((u) => [u.provider, u]));
+  }
+
+  async signIn(user: OAuthSignInDto) {
+    const oauthUser = await this.prisma.oAuthUser.findFirst({
+      where: {
+        provider: user.provider,
+        providerUserId: user.providerId,
+      },
+      include: {
+        user: true,
+      },
+    });
+    if (oauthUser) {
+      return this.auth.generateToken(oauthUser.user, true);
+    }
+
+    return this.signUp(user);
+  }
+
+  async link(
+    userId: string,
+    provider: string,
+    providerUserId: string,
+    providerUsername: string,
+  ) {
+    const oauthUser = await this.prisma.oAuthUser.findFirst({
+      where: {
+        provider,
+        providerUserId,
+      },
+    });
+    if (oauthUser) {
+      throw new ErrorPageException("already_linked", "/account", [
+        `provider_${provider}`,
+      ]);
+    }
+
+    await this.prisma.oAuthUser.create({
+      data: {
+        userId,
+        provider,
+        providerUsername,
+        providerUserId,
+      },
+    });
+  }
+
+  async unlink(user: User, provider: string) {
+    const oauthUser = await this.prisma.oAuthUser.findFirst({
+      where: {
+        userId: user.id,
+        provider,
+      },
+    });
+    if (oauthUser) {
+      await this.prisma.oAuthUser.delete({
+        where: {
+          id: oauthUser.id,
+        },
+      });
+    } else {
+      throw new ErrorPageException("not_linked", "/account", [provider]);
+    }
+  }
+
+  private async getAvailableUsername(email: string) {
+    // only remove + and - from email for now (maybe not enough)
+    let username = email.split("@")[0].replace(/[+-]/g, "").substring(0, 20);
+    while (true) {
+      const user = await this.prisma.user.findFirst({
+        where: {
+          username: username,
+        },
+      });
+      if (user) {
+        username = username + "_" + nanoid(10).replaceAll("-", "");
+      } else {
+        return username;
+      }
+    }
+  }
+
+  private async signUp(user: OAuthSignInDto) {
+    // register
+    if (!this.config.get("oauth.allowRegistration")) {
+      throw new ErrorPageException("no_user", "/auth/signIn", [
+        `provider_${user.provider}`,
+      ]);
+    }
+
+    if (!user.email) {
+      throw new ErrorPageException("no_email", "/auth/signIn", [
+        `provider_${user.provider}`,
+      ]);
+    }
+
+    const existingUser: User = await this.prisma.user.findFirst({
+      where: {
+        email: user.email,
+      },
+    });
+
+    if (existingUser) {
+      await this.prisma.oAuthUser.create({
+        data: {
+          provider: user.provider,
+          providerUserId: user.providerId.toString(),
+          providerUsername: user.providerUsername,
+          userId: existingUser.id,
+        },
+      });
+      return this.auth.generateToken(existingUser, true);
+    }
+
+    const result = await this.auth.signUp({
+      email: user.email,
+      username: await this.getAvailableUsername(user.email),
+      password: null,
+    });
+
+    await this.prisma.oAuthUser.create({
+      data: {
+        provider: user.provider,
+        providerUserId: user.providerId.toString(),
+        providerUsername: user.providerUsername,
+        userId: result.user.id,
+      },
+    });
+
+    return result;
+  }
+}

backend/src/oauth/provider/discord.provider.ts

@@ -0,0 +1,98 @@
+import { OAuthProvider, OAuthToken } from "./oauthProvider.interface";
+import { OAuthCallbackDto } from "../dto/oauthCallback.dto";
+import { OAuthSignInDto } from "../dto/oauthSignIn.dto";
+import { ConfigService } from "../../config/config.service";
+import { BadRequestException, Injectable } from "@nestjs/common";
+import fetch from "node-fetch";
+
+@Injectable()
+export class DiscordProvider implements OAuthProvider<DiscordToken> {
+  constructor(private config: ConfigService) {}
+
+  getAuthEndpoint(state: string): Promise<string> {
+    return Promise.resolve(
+      "https://discord.com/api/oauth2/authorize?" +
+        new URLSearchParams({
+          client_id: this.config.get("oauth.discord-clientId"),
+          redirect_uri:
+            this.config.get("general.appUrl") + "/api/oauth/callback/discord",
+          response_type: "code",
+          state: state,
+          scope: "identify email",
+        }).toString(),
+    );
+  }
+
+  private getAuthorizationHeader() {
+    return (
+      "Basic " +
+      Buffer.from(
+        this.config.get("oauth.discord-clientId") +
+          ":" +
+          this.config.get("oauth.discord-clientSecret"),
+      ).toString("base64")
+    );
+  }
+
+  async getToken(query: OAuthCallbackDto): Promise<OAuthToken<DiscordToken>> {
+    const res = await fetch("https://discord.com/api/v10/oauth2/token", {
+      method: "post",
+      headers: {
+        "Content-Type": "application/x-www-form-urlencoded",
+        Authorization: this.getAuthorizationHeader(),
+      },
+      body: new URLSearchParams({
+        code: query.code,
+        grant_type: "authorization_code",
+        redirect_uri:
+          this.config.get("general.appUrl") + "/api/oauth/callback/discord",
+      }),
+    });
+    const token: DiscordToken = await res.json();
+    return {
+      accessToken: token.access_token,
+      refreshToken: token.refresh_token,
+      expiresIn: token.expires_in,
+      scope: token.scope,
+      tokenType: token.token_type,
+      rawToken: token,
+    };
+  }
+
+  async getUserInfo(token: OAuthToken<DiscordToken>): Promise<OAuthSignInDto> {
+    const res = await fetch("https://discord.com/api/v10/user/@me", {
+      method: "post",
+      headers: {
+        Accept: "application/json",
+        Authorization: `${token.tokenType || "Bearer"} ${token.accessToken}`,
+      },
+    });
+    const user = (await res.json()) as DiscordUser;
+    if (user.verified === false) {
+      throw new BadRequestException("Unverified account.");
+    }
+
+    return {
+      provider: "discord",
+      providerId: user.id,
+      providerUsername: user.global_name ?? user.username,
+      email: user.email,
+    };
+  }
+}
+
+export interface DiscordToken {
+  access_token: string;
+  token_type: string;
+  expires_in: number;
+  refresh_token: string;
+  scope: string;
+}
+
+export interface DiscordUser {
+  id: string;
+  username: string;
+  global_name: string;
+  email: string;
+  verified: boolean;
+}

backend/src/oauth/provider/genericOidc.provider.ts

@@ -0,0 +1,206 @@
+import { BadRequestException } from "@nestjs/common";
+import fetch from "node-fetch";
+import { ConfigService } from "../../config/config.service";
+import { JwtService } from "@nestjs/jwt";
+import { Cache } from "cache-manager";
+import { nanoid } from "nanoid";
+import { OAuthCallbackDto } from "../dto/oauthCallback.dto";
+import { OAuthProvider, OAuthToken } from "./oauthProvider.interface";
+import { OAuthSignInDto } from "../dto/oauthSignIn.dto";
+
+export abstract class GenericOidcProvider implements OAuthProvider<OidcToken> {
+  protected redirectUri: string;
+  protected discoveryUri: string;
+  private configuration: OidcConfigurationCache;
+  private jwk: OidcJwkCache;
+
+  protected constructor(
+    protected name: string,
+    protected keyOfConfigUpdateEvents: string[],
+    protected config: ConfigService,
+    protected jwtService: JwtService,
+    protected cache: Cache,
+  ) {
+    this.discoveryUri = this.getDiscoveryUri();
+    this.redirectUri = `${this.config.get(
+      "general.appUrl",
+    )}/api/oauth/callback/${this.name}`;
+    this.config.addListener("update", (key: string, _: unknown) => {
+      if (this.keyOfConfigUpdateEvents.includes(key)) {
+        this.deinit();
+        this.discoveryUri = this.getDiscoveryUri();
+      }
+    });
+  }
+
+  async getConfiguration(): Promise<OidcConfiguration> {
+    if (!this.configuration || this.configuration.expires < Date.now()) {
+      await this.fetchConfiguration();
+    }
+    return this.configuration.data;
+  }
+
+  async getJwk(): Promise<OidcJwk[]> {
+    if (!this.jwk || this.jwk.expires < Date.now()) {
+      await this.fetchJwk();
+    }
+    return this.jwk.data;
+  }
+
+  async getAuthEndpoint(state: string) {
+    const configuration = await this.getConfiguration();
+    const endpoint = configuration.authorization_endpoint;
+
+    const nonce = nanoid();
+    await this.cache.set(
+      `oauth-${this.name}-nonce-${state}`,
+      nonce,
+      1000 * 60 * 5,
+    );
+
+    return (
+      endpoint +
+      "?" +
+      new URLSearchParams({
+        client_id: this.config.get(`oauth.${this.name}-clientId`),
+        response_type: "code",
+        scope: "openid profile email",
+        redirect_uri: this.redirectUri,
+        state,
+        nonce,
+      }).toString()
+    );
+  }
+
+  async getToken(query: OAuthCallbackDto): Promise<OAuthToken<OidcToken>> {
+    const configuration = await this.getConfiguration();
+    const endpoint = configuration.token_endpoint;
+    const res = await fetch(endpoint, {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/x-www-form-urlencoded",
+      },
+      body: new URLSearchParams({
+        client_id: this.config.get(`oauth.${this.name}-clientId`),
+        client_secret: this.config.get(`oauth.${this.name}-clientSecret`),
+        grant_type: "authorization_code",
+        code: query.code,
+        redirect_uri: this.redirectUri,
+      }).toString(),
+    });
+    const token: OidcToken = await res.json();
+    return {
+      accessToken: token.access_token,
+      expiresIn: token.expires_in,
+      idToken: token.id_token,
+      refreshToken: token.refresh_token,
+      tokenType: token.token_type,
+      rawToken: token,
+    };
+  }
+
+  async getUserInfo(
+    token: OAuthToken<OidcToken>,
+    query: OAuthCallbackDto,
+  ): Promise<OAuthSignInDto> {
+    const idTokenData = this.decodeIdToken(token.idToken);
+    // maybe it's not necessary to verify the id token since it's directly obtained from the provider
+
+    const key = `oauth-${this.name}-nonce-${query.state}`;
+    const nonce = await this.cache.get(key);
+    await this.cache.del(key);
+    if (nonce !== idTokenData.nonce) {
+      throw new BadRequestException("Invalid token");
+    }
+
+    return {
+      provider: this.name as any,
+      email: idTokenData.email,
+      providerId: idTokenData.sub,
+      providerUsername: idTokenData.name,
+    };
+  }
+
+  protected abstract getDiscoveryUri(): string;
+
+  private async fetchConfiguration(): Promise<void> {
+    const res = await fetch(this.discoveryUri);
+    const expires = res.headers.has("expires")
+      ? new Date(res.headers.get("expires")).getTime()
+      : Date.now() + 1000 * 60 * 60 * 24;
+    this.configuration = {
+      expires,
+      data: await res.json(),
+    };
+  }
+
+  private async fetchJwk(): Promise<void> {
+    const configuration = await this.getConfiguration();
+    const res = await fetch(configuration.jwks_uri);
+    const expires = res.headers.has("expires")
+      ? new Date(res.headers.get("expires")).getTime()
+      : Date.now() + 1000 * 60 * 60 * 24;
+    this.jwk = {
+      expires,
+      data: (await res.json())["keys"],
+    };
+  }
+
+  private deinit() {
+    this.discoveryUri = undefined;
+    this.configuration = undefined;
+    this.jwk = undefined;
+  }
+
+  private decodeIdToken(idToken: string): OidcIdToken {
+    return this.jwtService.decode(idToken) as OidcIdToken;
+  }
+}
+
+export interface OidcCache<T> {
+  expires: number;
+  data: T;
+}
+
+export interface OidcConfiguration {
+  issuer: string;
+  authorization_endpoint: string;
+  token_endpoint: string;
+  userinfo_endpoint?: string;
+  jwks_uri: string;
+  response_types_supported: string[];
+  id_token_signing_alg_values_supported: string[];
+  scopes_supported?: string[];
+  claims_supported?: string[];
+}
+
+export interface OidcJwk {
+  e: string;
+  alg: string;
+  kid: string;
+  use: string;
+  kty: string;
+  n: string;
+}
+
+export type OidcConfigurationCache = OidcCache<OidcConfiguration>;
+
+export type OidcJwkCache = OidcCache<OidcJwk[]>;
+
+export interface OidcToken {
+  access_token: string;
+  refresh_token: string;
+  token_type: string;
+  expires_in: number;
+  id_token: string;
+}
+
+export interface OidcIdToken {
+  iss: string;
+  sub: string;
+  exp: number;
+  iat: number;
+  email: string;
+  name: string;
+  nonce: string;
+}

backend/src/oauth/provider/github.provider.ts

@@ -0,0 +1,110 @@
+import { OAuthProvider, OAuthToken } from "./oauthProvider.interface";
+import { OAuthCallbackDto } from "../dto/oauthCallback.dto";
+import { OAuthSignInDto } from "../dto/oauthSignIn.dto";
+import { ConfigService } from "../../config/config.service";
+import fetch from "node-fetch";
+import { BadRequestException, Injectable } from "@nestjs/common";
+
+@Injectable()
+export class GitHubProvider implements OAuthProvider<GitHubToken> {
+  constructor(private config: ConfigService) {}
+
+  getAuthEndpoint(state: string): Promise<string> {
+    return Promise.resolve(
+      "https://github.com/login/oauth/authorize?" +
+        new URLSearchParams({
+          client_id: this.config.get("oauth.github-clientId"),
+          redirect_uri:
+            this.config.get("general.appUrl") + "/api/oauth/callback/github",
+          state: state,
+          scope: "user:email",
+        }).toString(),
+    );
+  }
+
+  async getToken(query: OAuthCallbackDto): Promise<OAuthToken<GitHubToken>> {
+    const res = await fetch(
+      "https://github.com/login/oauth/access_token?" +
+        new URLSearchParams({
+          client_id: this.config.get("oauth.github-clientId"),
+          client_secret: this.config.get("oauth.github-clientSecret"),
+          code: query.code,
+        }).toString(),
+      {
+        method: "post",
+        headers: {
+          Accept: "application/json",
+        },
+      },
+    );
+    const token: GitHubToken = await res.json();
+    return {
+      accessToken: token.access_token,
+      tokenType: token.token_type,
+      rawToken: token,
+    };
+  }
+
+  async getUserInfo(token: OAuthToken<GitHubToken>): Promise<OAuthSignInDto> {
+    const user = await this.getGitHubUser(token);
+    if (!token.scope.includes("user:email")) {
+      throw new BadRequestException("No email permission granted");
+    }
+    const email = await this.getGitHubEmail(token);
+    if (!email) {
+      throw new BadRequestException("No email found");
+    }
+
+    return {
+      provider: "github",
+      providerId: user.id.toString(),
+      providerUsername: user.name ?? user.login,
+      email,
+    };
+  }
+
+  private async getGitHubUser(
+    token: OAuthToken<GitHubToken>,
+  ): Promise<GitHubUser> {
+    const res = await fetch("https://api.github.com/user", {
+      headers: {
+        Accept: "application/vnd.github+json",
+        Authorization: `${token.tokenType ?? "Bearer"} ${token.accessToken}`,
+      },
+    });
+    return (await res.json()) as GitHubUser;
+  }
+
+  private async getGitHubEmail(
+    token: OAuthToken<GitHubToken>,
+  ): Promise<string | undefined> {
+    const res = await fetch("https://api.github.com/user/public_emails", {
+      headers: {
+        Accept: "application/vnd.github+json",
+        Authorization: `${token.tokenType ?? "Bearer"} ${token.accessToken}`,
+      },
+    });
+    const emails = (await res.json()) as GitHubEmail[];
+    return emails.find((e) => e.primary && e.verified)?.email;
+  }
+}
+
+export interface GitHubToken {
+  access_token: string;
+  token_type: string;
+  scope: string;
+}
+
+export interface GitHubUser {
+  login: string;
+  id: number;
+  name?: string;
+  email?: string; // this filed seems only return null
+}
+
+export interface GitHubEmail {
+  email: string;
+  primary: boolean;
+  verified: boolean;
+  visibility: string | null;
+}

backend/src/oauth/provider/google.provider.ts

@@ -0,0 +1,21 @@
+import { GenericOidcProvider } from "./genericOidc.provider";
+import { ConfigService } from "../../config/config.service";
+import { JwtService } from "@nestjs/jwt";
+import { Inject, Injectable } from "@nestjs/common";
+import { CACHE_MANAGER } from "@nestjs/cache-manager";
+import { Cache } from "cache-manager";
+
+@Injectable()
+export class GoogleProvider extends GenericOidcProvider {
+  constructor(
+    config: ConfigService,
+    jwtService: JwtService,
+    @Inject(CACHE_MANAGER) cache: Cache,
+  ) {
+    super("google", ["oauth.google-enabled"], config, jwtService, cache);
+  }
+
+  protected getDiscoveryUri(): string {
+    return "https://accounts.google.com/.well-known/openid-configuration";
+  }
+}

backend/src/oauth/provider/microsoft.provider.ts

@@ -0,0 +1,29 @@
+import { GenericOidcProvider } from "./genericOidc.provider";
+import { ConfigService } from "../../config/config.service";
+import { JwtService } from "@nestjs/jwt";
+import { Inject, Injectable } from "@nestjs/common";
+import { CACHE_MANAGER } from "@nestjs/cache-manager";
+import { Cache } from "cache-manager";
+
+@Injectable()
+export class MicrosoftProvider extends GenericOidcProvider {
+  constructor(
+    config: ConfigService,
+    jwtService: JwtService,
+    @Inject(CACHE_MANAGER) cache: Cache,
+  ) {
+    super(
+      "microsoft",
+      ["oauth.microsoft-enabled", "oauth.microsoft-tenant"],
+      config,
+      jwtService,
+      cache,
+    );
+  }
+
+  protected getDiscoveryUri(): string {
+    return `https://login.microsoftonline.com/${this.config.get(
+      "oauth.microsoft-tenant",
+    )}/v2.0/.well-known/openid-configuration`;
+  }
+}

backend/src/oauth/provider/oauthProvider.interface.ts

@@ -0,0 +1,24 @@
+import { OAuthCallbackDto } from "../dto/oauthCallback.dto";
+import { OAuthSignInDto } from "../dto/oauthSignIn.dto";
+
+/**
+ * @typeParam T - type of token
+ * @typeParam C - type of callback query
+ */
+export interface OAuthProvider<T, C = OAuthCallbackDto> {
+  getAuthEndpoint(state: string): Promise<string>;
+
+  getToken(query: C): Promise<OAuthToken<T>>;
+
+  getUserInfo(token: OAuthToken<T>, query: C): Promise<OAuthSignInDto>;
+}
+
+export interface OAuthToken<T> {
+  accessToken: string;
+  expiresIn?: number;
+  refreshToken?: string;
+  tokenType?: string;
+  scope?: string;
+  idToken?: string;
+  rawToken: T;
+}

backend/src/oauth/provider/oidc.provider.ts

@@ -0,0 +1,27 @@
+import { GenericOidcProvider } from "./genericOidc.provider";
+import { Inject, Injectable } from "@nestjs/common";
+import { ConfigService } from "../../config/config.service";
+import { JwtService } from "@nestjs/jwt";
+import { CACHE_MANAGER } from "@nestjs/cache-manager";
+import { Cache } from "cache-manager";
+
+@Injectable()
+export class OidcProvider extends GenericOidcProvider {
+  constructor(
+    config: ConfigService,
+    jwtService: JwtService,
+    @Inject(CACHE_MANAGER) protected cache: Cache,
+  ) {
+    super(
+      "oidc",
+      ["oauth.oidc-enabled", "oauth.oidc-discoveryUri"],
+      config,
+      jwtService,
+      cache,
+    );
+  }
+
+  protected getDiscoveryUri(): string {
+    return this.config.get("oauth.oidc-discoveryUri");
+  }
+}

backend/src/user/dto/user.dto.ts

@@ -16,6 +16,9 @@ export class UserDTO {
   @IsEmail()
   email: string;
 
+  @Expose()
+  hasPassword: boolean;
+
   @MinLength(8)
   password: string;
 

backend/src/user/user.controller.ts

@@ -28,7 +28,9 @@ export class UserController {
   @Get("me")
   @UseGuards(JwtGuard)
   async getCurrentUser(@GetUser() user: User) {
-    return new UserDTO().from(user);
+    const userDTO = new UserDTO().from(user);
+    userDTO.hasPassword = !!user.password;
+    return userDTO;
   }
 
   @Patch("me")