Add server to generate f parameters for NSO app authentication

src/api/f.ts

@@ -4,6 +4,7 @@ import { ErrorResponse } from './util.js';
 
 const debugS2s = createDebug('api:s2s');
 const debugFlapg = createDebug('api:flapg');
+const debugZncaApi = createDebug('api:znca-api');
 
 export async function getLoginHash(token: string, timestamp: string | number) {
     debugS2s('Getting login hash');
@@ -56,6 +57,51 @@ export async function flapg(token: string, timestamp: string | number, guid: str
     return data.result;
 }
 
+export async function genf(url: string, token: string, timestamp: string | number, uuid: string, type: FlapgIid) {
+    debugZncaApi('Getting f parameter', {
+        url, token, timestamp, uuid,
+    });
+
+    const req: AndroidZncaFRequest = {
+        type,
+        token,
+        timestamp: '' + timestamp,
+        uuid,
+    };
+
+    const response = await fetch(url, {
+        method: 'POST',
+        headers: {
+            'Content-Type': 'application/json',
+        },
+        body: JSON.stringify(req),
+    });
+
+    const data = await response.json() as AndroidZncaFResponse | AndroidZncaFError;
+
+    if ('error' in data) {
+        debugZncaApi('Error getting f parameter "%s"', data.error);
+        throw new ErrorResponse('[znca-api] ' + data.error, response, data);
+    }
+
+    debugZncaApi('Got f parameter "%s"', data.f);
+
+    return data.f;
+}
+
+export async function genfc(url: string, token: string, timestamp: string | number, uuid: string, type: FlapgIid) {
+    const f = await genf(url, token, timestamp, uuid, type);
+
+    return {
+        f,
+        p1: token,
+        p2: '' + timestamp,
+        p3: uuid,
+
+        url,
+    };
+}
+
 export interface LoginHashApiResponse {
     hash: string;
 }
@@ -78,3 +124,16 @@ export interface FlapgApiResponse {
         p3: string;
     };
 }
+
+export interface AndroidZncaFRequest {
+    type: FlapgIid;
+    token: string;
+    timestamp: string;
+    uuid: string;
+}
+export interface AndroidZncaFResponse {
+    f: string;
+}
+export interface AndroidZncaFError {
+    error: string;
+}

src/api/znc.ts

@@ -1,7 +1,7 @@
 import fetch from 'node-fetch';
 import { v4 as uuidgen } from 'uuid';
 import createDebug from 'debug';
-import { flapg, FlapgIid } from './f.js';
+import { flapg, FlapgIid, genfc } from './f.js';
 import { AccountLogin, ActiveEvent, Announcement, CurrentUser, Friends, WebService, WebServiceToken, ZncResponse } from './znc-types.js';
 import { getNintendoAccountToken, getNintendoAccountUser } from './na.js';
 import { ErrorResponse } from './util.js';
@@ -76,14 +76,16 @@ export default class ZncApi {
         const uuid = uuidgen();
         const timestamp = '' + Math.floor(Date.now() / 1000);
 
-        const data = await flapg(nintendoAccountToken, timestamp, uuid, FlapgIid.APP);
+        const data = process.env.ZNCA_API_URL ?
+            await genfc(process.env.ZNCA_API_URL + '/f', nintendoAccountToken, timestamp, uuid, FlapgIid.APP) :
+            await flapg(nintendoAccountToken, timestamp, uuid, FlapgIid.APP);
 
         const req = {
             id,
             registrationToken: nintendoAccountToken,
             f: data.f,
-            requestId: data.p3,
-            timestamp: data.p2,
+            requestId: uuid,
+            timestamp,
         };
 
         return this.fetch<WebServiceToken>('/v2/Game/GetWebServiceToken', 'POST', JSON.stringify({
@@ -118,7 +120,9 @@ export default class ZncApi {
         // Nintendo Account user data
         const user = await getNintendoAccountUser(nintendoAccountToken);
 
-        const flapgdata = await flapg(nintendoAccountToken.id_token, timestamp, uuid, FlapgIid.NSO);
+        const flapgdata = process.env.ZNCA_API_URL ?
+            await genfc(process.env.ZNCA_API_URL + '/f', nintendoAccountToken.id_token, timestamp, uuid, FlapgIid.NSO) :
+            await flapg(nintendoAccountToken.id_token, timestamp, uuid, FlapgIid.NSO);
 
         debug('Getting Nintendo Switch Online app token');
 
@@ -132,12 +136,12 @@ export default class ZncApi {
             },
             body: JSON.stringify({
                 parameter: {
-                    naIdToken: flapgdata.p1,
+                    naIdToken: nintendoAccountToken.id_token,
                     naBirthday: user.birthday,
                     naCountry: user.country,
                     language: user.language,
-                    timestamp: flapgdata.p2,
-                    requestId: flapgdata.p3,
+                    timestamp,
+                    requestId: uuid,
                     f: flapgdata.f,
                 },
             }),