feat(oauth): Add an OAuth-sessionToken exchange endpoint

docs/api.md

@@ -24,6 +24,7 @@ see [`mozilla/fxa-js-client`](https://github.com/mozilla/fxa-js-client).
   * [Account](#account)
     * [POST /account/create](#post-accountcreate)
     * [POST /account/login](#post-accountlogin)
+    * [GET /account/oauth_exchange (:lock: oauthToken)](#get-accountoauth_exchange)
     * [GET /account/status (:lock::unlock: sessionToken)](#get-accountstatus)
     * [POST /account/status](#post-accountstatus)
     * [GET /account/profile (:lock: sessionToken, oauthToken)](#get-accountprofile)
@@ -295,6 +296,8 @@ for `code` and `errno` are:
   This request requires two step authentication enabled on your account.
 * `code: 400, errno: 161`:
   Recovery key already exists.
+* `code: 401, errno: 162`:
+  The required scope(s) for this request was not found.
 * `code: 503, errno: 201`:
   Service unavailable
 * `code: 503, errno: 202`:
@@ -327,6 +330,7 @@ include additional response properties:
 * `errno: 135`: bouncedAt
 * `errno: 152`
 * `errno: 153`
+* `errno: 162`: requiredScopes
 * `errno: 201`: retryAfter
 * `errno: 202`: retryAfter
 * `errno: 203`: service, operation
@@ -716,6 +720,23 @@ by the following errors
   This request requires two step authentication enabled on your account.
 
 
+#### GET /account/oauth_exchange
+
+:lock: authenticated with OAuth bearer token
+<!--begin-route-get-accountoauth_exchange-->
+
+<!--end-route-get-accountoauth_exchange-->
+
+##### Error responses
+
+Failing requests may be caused
+by the following errors
+(this is not an exhaustive list):
+
+* `code: 401, errno: 162`:
+  The required scope(s) for this request was not found.
+
+
 #### GET /account/status
 
 :lock::unlock: Optionally HAWK-authenticated with session token

lib/error.js

@@ -75,6 +75,8 @@ var ERRNO = {
   TOTP_REQUIRED: 160,
   RECOVERY_KEY_EXISTS: 161,
 
+  INVALID_SCOPE: 162,
+
   SERVER_BUSY: 201,
   FEATURE_NOT_ENABLED: 202,
   BACKEND_SERVICE_FAILURE: 203,
@@ -851,6 +853,17 @@ AppError.backendServiceFailure = (service, operation) => {
   })
 }
 
+AppError.invalidScope = (requiredScopes) => {
+  return new AppError({
+    code: 401,
+    error: 'Unauthorized',
+    errno: ERRNO.INVALID_SCOPE,
+    message: 'The required scope(s) for this request was not found.'
+  }, {
+    requiredScopes
+  })
+}
+
 AppError.unexpectedError = () => {
   return new AppError({})
 }

lib/routes/account.js

@@ -22,6 +22,8 @@ const MS_ONE_DAY = MS_ONE_HOUR * 24
 const MS_ONE_WEEK = MS_ONE_DAY * 7
 const MS_ONE_MONTH = MS_ONE_DAY * 30
 
+const SCOPE_ADMIN = 'https://identity.mozilla.com/admin'
+
 module.exports = (log, db, mailer, Password, config, customs, signinUtils, push) => {
   const tokenCodeConfig = config.signinConfirmation.tokenVerificationCode
   const tokenCodeLifetime = tokenCodeConfig && tokenCodeConfig.codeLifetime || MS_ONE_HOUR
@@ -726,6 +728,59 @@ module.exports = (log, db, mailer, Password, config, customs, signinUtils, push)
         }
       }
     },
+    {
+      method: 'GET',
+      path: '/account/oauth_exchange',
+      options: {
+        auth: {
+          strategy: 'oauthToken',
+          payload: false, // no payload authentication in OAuth.
+        },
+        response: {
+          schema: {
+            sessionToken: isA.string().regex(HEX_STRING).required(),
+          }
+        }
+      },
+      handler: async function (request) {
+        const auth = request.auth
+        const uid = auth.credentials.user;
+        const scope = ScopeSet.fromArray(auth.credentials.scope);
+        if (! scope.contains(SCOPE_ADMIN)) {
+          throw error.invalidScope(SCOPE_ADMIN)
+        }
+
+        const account = await db.account(uid);
+        const {
+          browser: uaBrowser,
+          browserVersion: uaBrowserVersion,
+          os: uaOS,
+          osVersion: uaOSVersion,
+          deviceType: uaDeviceType,
+          formFactor: uaFormFactor
+        } = request.app.ua
+
+        const sessionToken = await db.createSessionToken({
+          uid: account.uid,
+          email: account.email,
+          emailCode: account.emailCode,
+          emailVerified: account.emailVerified,
+          verifierSetAt: account.verifierSetAt,
+          mustVerify: false,
+          tokenVerificationCode: undefined,
+          tokenVerificationCodeExpiresAt: undefined,
+          tokenVerificationId: undefined,
+          uaBrowser,
+          uaBrowserVersion,
+          uaOS,
+          uaOSVersion,
+          uaDeviceType,
+          uaFormFactor
+        })
+
+        return {sessionToken: sessionToken.data}
+      }
+    },
     {
       method: 'GET',
       path: '/account/status',