feat(core): allow clearing cookies from jwt() (#6337)

* feat(core): allow clearing cookies from `jwt()` * revert: allow clearing cookies from `jwt()` * feat(core): re-apply changes against `@auth/core` * revert: `decodeJWT` option * doc: `jwt()` callback * Apply suggestions from code review Co-authored-by: Balázs Orbán <info@balazsorban.com>
nextauthjs · Jan 10, 2023 · 6d4cde4 · 6d4cde4 · vercel · Jan 10, 2023
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diff --git a/packages/core/src/lib/routes/callback.ts b/packages/core/src/lib/routes/callback.ts
@@ -111,17 +111,22 @@ export async function callback(params: {
           isNewUser,
         })
 
-        // Encode token
-        const newToken = await jwt.encode({ ...jwt, token })
-
-        // Set cookie expiry date
-        const cookieExpires = new Date()
-        cookieExpires.setTime(cookieExpires.getTime() + sessionMaxAge * 1000)
-
-        const sessionCookies = sessionStore.chunk(newToken, {
-          expires: cookieExpires,
-        })
-        cookies.push(...sessionCookies)
+        // Clear cookies if token is null
+        if (token === null) {
+          cookies.push(...sessionStore.clean())
+        } else {
+          // Encode token
+          const newToken = await jwt.encode({ ...jwt, token })
+
+          // Set cookie expiry date
+          const cookieExpires = new Date()
+          cookieExpires.setTime(cookieExpires.getTime() + sessionMaxAge * 1000)
+
+          const sessionCookies = sessionStore.chunk(newToken, {
+            expires: cookieExpires,
+          })
+          cookies.push(...sessionCookies)
+        }
       } else {
         // Save Session Token in cookie
         cookies.push({
@@ -214,17 +219,22 @@ export async function callback(params: {
           isNewUser,
         })
 
-        // Encode token
-        const newToken = await jwt.encode({ ...jwt, token })
-
-        // Set cookie expiry date
-        const cookieExpires = new Date()
-        cookieExpires.setTime(cookieExpires.getTime() + sessionMaxAge * 1000)
-
-        const sessionCookies = sessionStore.chunk(newToken, {
-          expires: cookieExpires,
-        })
-        cookies.push(...sessionCookies)
+        // Clear cookies if token is null
+        if (token === null) {
+          cookies.push(...sessionStore.clean())
+        } else {
+          // Encode token
+          const newToken = await jwt.encode({ ...jwt, token })
+
+          // Set cookie expiry date
+          const cookieExpires = new Date()
+          cookieExpires.setTime(cookieExpires.getTime() + sessionMaxAge * 1000)
+
+          const sessionCookies = sessionStore.chunk(newToken, {
+            expires: cookieExpires,
+          })
+          cookies.push(...sessionCookies)
+        }
       } else {
         // Save Session Token in cookie
         cookies.push({
@@ -305,18 +315,23 @@ export async function callback(params: {
         isNewUser: false,
       })
 
-      // Encode token
-      const newToken = await jwt.encode({ ...jwt, token })
+      // Clear cookies if token is null
+      if (token === null) {
+        cookies.push(...sessionStore.clean())
+      } else {
+        // Encode token
+        const newToken = await jwt.encode({ ...jwt, token })
 
-      // Set cookie expiry date
-      const cookieExpires = new Date()
-      cookieExpires.setTime(cookieExpires.getTime() + sessionMaxAge * 1000)
+        // Set cookie expiry date
+        const cookieExpires = new Date()
+        cookieExpires.setTime(cookieExpires.getTime() + sessionMaxAge * 1000)
 
-      const sessionCookies = sessionStore.chunk(newToken, {
-        expires: cookieExpires,
-      })
+        const sessionCookies = sessionStore.chunk(newToken, {
+          expires: cookieExpires,
+        })
 
-      cookies.push(...sessionCookies)
+        cookies.push(...sessionCookies)
+      }
 
       // @ts-expect-error
       await events.signIn?.({ user, account })

diff --git a/packages/core/src/lib/routes/session.ts b/packages/core/src/lib/routes/session.ts
@@ -48,27 +48,32 @@ export async function session(
 
       // @ts-expect-error
       const token = await callbacks.jwt({ token: decodedToken })
-      // @ts-expect-error
-      const newSession = await callbacks.session({ session, token })
 
-      // Return session payload as response
-      response.body = newSession
+      if (token !== null) {
+        // @ts-expect-error
+        const newSession = await callbacks.session({ session, token })
 
-      // Refresh JWT expiry by re-signing it, with an updated expiry date
-      const newToken = await jwt.encode({
-        ...jwt,
-        token,
-        maxAge: options.session.maxAge,
-      })
+        // Return session payload as response
+        response.body = newSession
 
-      // Set cookie, to also update expiry date on cookie
-      const sessionCookies = sessionStore.chunk(newToken, {
-        expires: newExpires,
-      })
+        // Refresh JWT expiry by re-signing it, with an updated expiry date
+        const newToken = await jwt.encode({
+          ...jwt,
+          token,
+          maxAge: options.session.maxAge,
+        })
+
+        // Set cookie, to also update expiry date on cookie
+        const sessionCookies = sessionStore.chunk(newToken, {
+          expires: newExpires,
+        })
 
-      response.cookies?.push(...sessionCookies)
+        response.cookies?.push(...sessionCookies)
 
-      await events.session?.({ session: newSession, token })
+        await events.session?.({ session: newSession, token })
+      } else {
+        response.cookies?.push(...sessionStore.clean())
+      } 
     } catch (e) {
       logger.error(new JWTSessionError(e as Error))
       // If the JWT is not verifiable remove the broken session cookie(s).

diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
@@ -203,6 +203,11 @@ export interface CallbacksOptions<P = Profile, A = Account> {
    * Its content is forwarded to the `session` callback,
    * where you can control what should be returned to the client.
    * Anything else will be kept inaccessible from the client.
+   * 
+   * Returning `null` will invalidate the JWT session by clearing
+   * the user's cookies. You'll still have to monitor and invalidate
+   * unexpired tokens from future requests yourself to prevent
+   * unauthorized access.
    *
    * By default the JWT is encrypted.
    *
@@ -215,7 +220,7 @@ export interface CallbacksOptions<P = Profile, A = Account> {
     account?: A | null
     profile?: P
     isNewUser?: boolean
-  }) => Awaitable<JWT>
+  }) => Awaitable<JWT|null>
 }
 
 /** [Documentation](https://authjs.dev/reference/configuration/auth-config#cookies) */