fix: cleanup start idp flow

apps/login/src/app/login/route.ts

@@ -25,7 +25,6 @@ import {
 import { CreateResponseRequestSchema } from "@zitadel/proto/zitadel/saml/v2/saml_service_pb";
 import { Session } from "@zitadel/proto/zitadel/session/v2/session_pb";
 import { IdentityProviderType } from "@zitadel/proto/zitadel/settings/v2/login_settings_pb";
-import { FormData } from "@zitadel/proto/zitadel/user/v2/idp_pb";
 import { headers } from "next/headers";
 import { NextRequest, NextResponse } from "next/server";
 import { DEFAULT_CSP } from "../../../constants/csp";
@@ -218,7 +217,7 @@ export async function GET(request: NextRequest) {
             params.set("organization", organization);
           }
 
-          return startIdentityProviderFlow({
+          const url = await startIdentityProviderFlow({
             serviceUrl,
             idpId,
             urls: {
@@ -229,25 +228,18 @@ export async function GET(request: NextRequest) {
                 `${origin}/idp/${provider}/failure?` +
                 new URLSearchParams(params),
             },
-          }).then((resp) => {
-            if (resp.nextStep.case === "authUrl" && resp.nextStep.value) {
-              return NextResponse.redirect(resp.nextStep.value);
-            } else if (
-              resp.nextStep.case === "formData" &&
-              resp.nextStep.value
-            ) {
-              const formData: FormData = resp.nextStep.value;
-
-              const redirectUrl = constructUrl(request, "/saml-post");
-
-              redirectUrl.searchParams.set("url", formData.url);
-              Object.entries(formData.fields).forEach(([k, v]) => {
-                redirectUrl.searchParams.set(k, v);
           });
 
-              return NextResponse.redirect(redirectUrl.toString());
+          if (!url) {
+            return NextResponse.json(
+              { error: "Could not start IDP flow" },
+              { status: 500 },
+            );
           }
-          });
+
+          const absoluteUrl = constructUrl(request, url);
+
+          return NextResponse.redirect(absoluteUrl);
         }
       }
     }

apps/login/src/lib/server/idp.ts

@@ -74,22 +74,20 @@ export type StartIDPFlowCommand = {
 async function startIDPFlow(command: StartIDPFlowCommand) {
   const basePath = process.env.NEXT_PUBLIC_BASE_PATH ?? "";
 
-  return startIdentityProviderFlow({
+  const url = await startIdentityProviderFlow({
     serviceUrl: command.serviceUrl,
     idpId: command.idpId,
     urls: {
       successUrl: `${command.host.includes("localhost") ? "http://" : "https://"}${command.host}${basePath}${command.successUrl}`,
       failureUrl: `${command.host.includes("localhost") ? "http://" : "https://"}${command.host}${basePath}${command.failureUrl}`,
     },
-  }).then((response) => {
-    if (
-      response &&
-      response.nextStep.case === "authUrl" &&
-      response?.nextStep.value
-    ) {
-      return { redirect: response.nextStep.value };
-    }
   });
+
+  if (!url) {
+    return { error: "Could not start IDP flow" };
+  }
+
+  return { redirect: url };
 }
 
 type CreateNewSessionCommand = {

apps/login/src/lib/server/loginname.ts

@@ -102,7 +102,7 @@ export async function sendLoginname(command: SendLoginnameCommand) {
 
       const basePath = process.env.NEXT_PUBLIC_BASE_PATH ?? "";
 
-      const resp = await startIdentityProviderFlow({
+      const url = await startIdentityProviderFlow({
         serviceUrl,
         idpId: identityProviders[0].id,
         urls: {
@@ -115,9 +115,11 @@ export async function sendLoginname(command: SendLoginnameCommand) {
         },
       });
 
-      if (resp?.nextStep.case === "authUrl") {
+      if (!url) {
-        return { redirect: resp.nextStep.value };
+        return { error: "Could not start IDP flow" };
       }
+
+      return { redirect: url };
     }
   };
 
@@ -166,7 +168,7 @@ export async function sendLoginname(command: SendLoginnameCommand) {
 
       const basePath = process.env.NEXT_PUBLIC_BASE_PATH ?? "";
 
-      const resp = await startIdentityProviderFlow({
+      const url = await startIdentityProviderFlow({
         serviceUrl,
         idpId: idp.id,
         urls: {
@@ -179,9 +181,11 @@ export async function sendLoginname(command: SendLoginnameCommand) {
         },
       });
 
-      if (resp?.nextStep.case === "authUrl") {
+      if (!url) {
-        return { redirect: resp.nextStep.value };
+        return { error: "Could not start IDP flow" };
       }
+
+      return { redirect: url };
     }
   };
 

apps/login/src/lib/zitadel.ts

@@ -23,7 +23,10 @@ import {
 import { LoginSettings } from "@zitadel/proto/zitadel/settings/v2/login_settings_pb";
 import { SettingsService } from "@zitadel/proto/zitadel/settings/v2/settings_service_pb";
 import { SendEmailVerificationCodeSchema } from "@zitadel/proto/zitadel/user/v2/email_pb";
-import type { RedirectURLsJson } from "@zitadel/proto/zitadel/user/v2/idp_pb";
+import type {
+  FormData,
+  RedirectURLsJson,
+} from "@zitadel/proto/zitadel/user/v2/idp_pb";
 import {
   NotificationType,
   SendPasswordResetLinkSchema,
@@ -964,18 +967,35 @@ export async function startIdentityProviderFlow({
   serviceUrl: string;
   idpId: string;
   urls: RedirectURLsJson;
-}) {
+}): Promise<string | null> {
   const userService: Client<typeof UserService> = await createServiceForHost(
     UserService,
     serviceUrl,
   );
 
-  return userService.startIdentityProviderIntent({
+  return userService
+    .startIdentityProviderIntent({
       idpId,
       content: {
         case: "urls",
         value: urls,
       },
+    })
+    .then((resp) => {
+      if (resp.nextStep.case === "authUrl" && resp.nextStep.value) {
+        return resp.nextStep.value;
+      } else if (resp.nextStep.case === "formData" && resp.nextStep.value) {
+        const formData: FormData = resp.nextStep.value;
+        const redirectUrl = new URL("/saml-post");
+
+        redirectUrl.searchParams.set("url", formData.url);
+        Object.entries(formData.fields).forEach(([k, v]) => {
+          redirectUrl.searchParams.set(k, v);
+        });
+
+        return redirectUrl.toString();
+      }
+      return null;
     });
 }