feat(api): add support for ClientCreds style cognito tokens

Before, only user creds were supported by the oauth2/token route.

src/__tests__/mockTokenGenerator.ts

@@ -2,4 +2,5 @@ import { TokenGenerator } from "../services/tokenGenerator";
 
 export const newMockTokenGenerator = (): jest.Mocked<TokenGenerator> => ({
   generate: jest.fn(),
+  generateWithClientCreds: jest.fn(),
 });

src/server/server.ts

@@ -68,7 +68,28 @@ export const createServer = (
     req.on("end", function () {
       const target = "GetToken";
       const route = router(target);
-      route({ logger: req.log }, rawBody).then(
+
+      const parsed = new URLSearchParams(rawBody);
+      const params = {
+        grant_type: parsed.get("grant_type"),
+        client_id: parsed.get("client_id"),
+        client_secret: parsed.get("client_secret"),
+        refresh_token: parsed.get("refresh_token"),
+      };
+
+      const auth = req.get("Authorization");
+      if (auth && auth.startsWith("Basic ")) {
+        const sliced = auth.slice("Basic ".length);
+        const buff = new Buffer(sliced, "base64");
+        const decoded = buff.toString("ascii");
+        const creds = decoded.split(":");
+        if (creds.length == 2) {
+          params.client_id = creds[0];
+          params.client_secret = creds[1];
+        }
+      }
+
+      route({ logger: req.log }, params).then(
         (output) => {
           res.status(200).type("json").send(JSON.stringify(output));
         },

src/services/tokenGenerator.ts

@@ -86,8 +86,8 @@ const applyTokenOverrides = (
 
 export interface Tokens {
   readonly AccessToken: string;
-  readonly IdToken: string;
-  readonly RefreshToken: string;
+  readonly IdToken?: string;
+  readonly RefreshToken?: string;
 }
 
 export interface TokenGenerator {
@@ -104,6 +104,10 @@ export interface TokenGenerator {
       | "NewPasswordChallenge"
       | "RefreshTokens"
   ): Promise<Tokens>;
+  generateWithClientCreds(
+    ctx: Context,
+    userPoolClient: AppClient
+  ): Promise<Tokens>;
 }
 
 const formatExpiration = (
@@ -240,4 +244,38 @@ export class JwtTokenGenerator implements TokenGenerator {
       ),
     };
   }
+
+  public async generateWithClientCreds(
+    ctx: Context,
+    userPoolClient: AppClient
+  ): Promise<Tokens> {
+    const eventId = uuid.v4();
+    const authTime = Math.floor(this.clock.get().getTime() / 1000);
+
+    const accessToken: RawToken = {
+      auth_time: authTime,
+      client_id: userPoolClient.ClientId,
+      event_id: eventId,
+      iat: authTime,
+      jti: uuid.v4(),
+      scope: "aws.cognito.signin.user.admin", // TODO: scopes
+      sub: userPoolClient.ClientId,
+      token_use: "access",
+    };
+
+    const issuer = `${this.tokenConfig.IssuerDomain}/${userPoolClient.UserPoolId}`;
+
+    return await Promise.resolve({
+      AccessToken: jwt.sign(accessToken, PrivateKey.pem, {
+        algorithm: "RS256",
+        issuer,
+        expiresIn: formatExpiration(
+          userPoolClient.AccessTokenValidity,
+          userPoolClient.TokenValidityUnits?.AccessToken ?? "hours",
+          "24h"
+        ),
+        keyid: "CognitoLocal",
+      }),
+    });
+  }
 }

src/targets/getToken.test.ts

@@ -1,20 +1,16 @@
-import {newMockCognitoService} from "../__tests__/mockCognitoService";
-import {newMockTokenGenerator} from "../__tests__/mockTokenGenerator";
-import {newMockTriggers} from "../__tests__/mockTriggers";
-import {newMockUserPoolService} from "../__tests__/mockUserPoolService";
-import {TestContext} from "../__tests__/testContext";
+import { newMockCognitoService } from "../__tests__/mockCognitoService";
+import { newMockTokenGenerator } from "../__tests__/mockTokenGenerator";
+import { newMockTriggers } from "../__tests__/mockTriggers";
+import { newMockUserPoolService } from "../__tests__/mockUserPoolService";
+import { TestContext } from "../__tests__/testContext";
 import * as TDB from "../__tests__/testDataBuilder";
-import {CognitoService, Triggers, UserPoolService} from "../services";
-import {TokenGenerator} from "../services/tokenGenerator";
+import { CognitoService, Triggers, UserPoolService } from "../services";
+import { TokenGenerator } from "../services/tokenGenerator";
 
-import {
-  GetToken,
-  GetTokenTarget,
-} from "./getToken";
+import { GetToken, GetTokenTarget } from "./getToken";
 
 describe("GetToken target", () => {
-  let target: GetTokenTarget;
-
+  let getToken: GetTokenTarget;
   let mockCognitoService: jest.Mocked<CognitoService>;
   let mockTokenGenerator: jest.Mocked<TokenGenerator>;
   let mockTriggers: jest.Mocked<Triggers>;
@@ -23,42 +19,82 @@ describe("GetToken target", () => {
 
   beforeEach(() => {
     mockUserPoolService = newMockUserPoolService({
-      Id : userPoolClient.UserPoolId,
+      Id: userPoolClient.UserPoolId,
     });
     mockCognitoService = newMockCognitoService(mockUserPoolService);
     mockCognitoService.getAppClient.mockResolvedValue(userPoolClient);
     mockTriggers = newMockTriggers();
     mockTokenGenerator = newMockTokenGenerator();
     getToken = GetToken({
-      triggers : mockTriggers,
-      cognito : mockCognitoService,
-      tokenGenerator : mockTokenGenerator,
+      cognito: mockCognitoService,
+      tokenGenerator: mockTokenGenerator,
     });
   });
 
   it("issues access tokens via refresh tokens", async () => {
     mockTokenGenerator.generate.mockResolvedValue({
-      AccessToken : "access",
-      IdToken : "id",
-      RefreshToken : "refresh",
+      AccessToken: "access",
+      IdToken: "id",
+      RefreshToken: "refresh",
     });
 
     const existingUser = TDB.user({
-      RefreshTokens : [ "refresh-orig" ],
+      RefreshTokens: ["refresh-orig"],
     });
     mockUserPoolService.getUserByRefreshToken.mockResolvedValue(existingUser);
     mockUserPoolService.listUserGroupMembership.mockResolvedValue([]);
 
-    const response = await getToken(
-        TestContext,
-        new URLSearchParams(`client_id=${
-            userPoolClient
-                .ClientId}&grant_type=refresh_token&refresh_token=refresh-orig`));
-    expect(mockUserPoolService.getUserByRefreshToken)
-        .toHaveBeenCalledWith(TestContext, "refresh-orig");
+    const response = await getToken(TestContext, {
+      client_id: userPoolClient.ClientId,
+      grant_type: "refresh_token",
+      refresh_token: "refresh-orig",
+    });
+    expect(mockUserPoolService.getUserByRefreshToken).toHaveBeenCalledWith(
+      TestContext,
+      "refresh-orig"
+    );
     expect(mockUserPoolService.storeRefreshToken).not.toHaveBeenCalled();
 
     expect(response.access_token).toEqual("access");
     expect(response.refresh_token).toEqual("refresh");
   });
 });
+
+describe("GetToken target - Client Creds", () => {
+  let getToken: GetTokenTarget;
+  let mockCognitoService: jest.Mocked<CognitoService>;
+  let mockTokenGenerator: jest.Mocked<TokenGenerator>;
+  let mockUserPoolService: jest.Mocked<UserPoolService>;
+  const userPoolClient = TDB.appClient({
+    ClientSecret: "secret",
+    ClientId: "id",
+  });
+
+  beforeEach(() => {
+    mockUserPoolService = newMockUserPoolService({
+      Id: userPoolClient.UserPoolId,
+    });
+    mockCognitoService = newMockCognitoService(mockUserPoolService);
+    mockCognitoService.getAppClient.mockResolvedValue(userPoolClient);
+    mockTokenGenerator = newMockTokenGenerator();
+    getToken = GetToken({
+      cognito: mockCognitoService,
+      tokenGenerator: mockTokenGenerator,
+    });
+  });
+
+  it("issues access tokens via client credentials", async () => {
+    mockTokenGenerator.generateWithClientCreds.mockResolvedValue({
+      AccessToken: "access",
+      RefreshToken: null,
+      IdToken: null,
+    });
+
+    const response = await getToken(TestContext, {
+      client_id: userPoolClient.ClientId,
+      client_secret: userPoolClient.ClientSecret,
+      grant_type: "client_credentials",
+    });
+    expect(response.access_token).toEqual("access");
+  });
+});

src/targets/getToken.ts

@@ -9,27 +9,42 @@ import { Target } from "../targets/Target";
 
 type HandleTokenServices = Pick<Services, "cognito" | "tokenGenerator">;
 
-type GetTokenRequest = URLSearchParams;
+export type GetTokenRequest =
+  | GetTokenRequestClientCreds
+  | GetTokenRequestRefreshToken
+  | GetTokenRequestAuthCode;
+
+interface GetTokenRequestGrantType {
+  grant_type: "authorization_code" | "client_credentials" | "refresh_token";
+  client_id: string;
+}
+
+interface GetTokenRequestClientCreds extends GetTokenRequestGrantType {
+  client_secret: string;
+}
+
+type GetTokenRequestAuthCode = GetTokenRequestGrantType;
+
+interface GetTokenRequestRefreshToken extends GetTokenRequestGrantType {
+  refresh_token: string;
+}
 
 interface GetTokenResponse {
   access_token: string;
-  refresh_token: string;
+  refresh_token?: string;
 }
 
 export type GetTokenTarget = Target<GetTokenRequest, GetTokenResponse>;
 
-async function getRefreshToken(
+async function getWithRefreshToken(
   ctx: Context,
   services: HandleTokenServices,
-  params: GetTokenRequest
+  params: GetTokenRequestRefreshToken
 ) {
-  const clientId = params.get("client_id");
+  const clientId = params.client_id;
   const userPool = await services.cognito.getUserPoolForClientId(ctx, clientId);
   const userPoolClient = await services.cognito.getAppClient(ctx, clientId);
-  const user = await userPool.getUserByRefreshToken(
-    ctx,
-    params.get("refresh_token")
-  );
+  const user = await userPool.getUserByRefreshToken(ctx, params.refresh_token);
   if (!user || !userPoolClient) {
     throw new NotAuthorizedError();
   }
@@ -51,21 +66,60 @@ async function getRefreshToken(
   };
 }
 
+async function getWithClientCredentials(
+  ctx: Context,
+  services: HandleTokenServices,
+  params: GetTokenRequestClientCreds
+) {
+  const clientId = params.client_id;
+  const clientSecret = params.client_secret;
+  const userPoolClient = await services.cognito.getAppClient(ctx, clientId);
+  if (!userPoolClient) {
+    throw new NotAuthorizedError();
+  }
+  if (
+    userPoolClient.ClientSecret &&
+    userPoolClient.ClientSecret != clientSecret
+  ) {
+    throw new NotAuthorizedError();
+  }
+
+  const tokens = await services.tokenGenerator.generateWithClientCreds(
+    ctx,
+    userPoolClient
+  );
+  if (!tokens) {
+    throw new NotAuthorizedError();
+  }
+
+  return {
+    access_token: tokens.AccessToken,
+  };
+}
+
 export const GetToken =
   (services: HandleTokenServices): GetTokenTarget =>
   async (ctx, req) => {
-    const params = new URLSearchParams(req);
-    switch (params.get("grant_type")) {
+    switch (req.grant_type) {
       case "authorization_code": {
         throw new NotImplementedError();
       }
       case "client_credentials": {
-        throw new NotImplementedError();
+        return getWithClientCredentials(
+          ctx,
+          services,
+          req as GetTokenRequestClientCreds
+        );
       }
       case "refresh_token": {
-        return getRefreshToken(ctx, services, params);
+        return getWithRefreshToken(
+          ctx,
+          services,
+          req as GetTokenRequestRefreshToken
+        );
       }
       default: {
+        console.log("Invalid grant type passed:", req.grant_type);
         throw new InvalidParameterError();
       }
     }