feat(api): add size check to app_data field in newPostSchema

Author: jonbarrow

apps/miiverse-api/src/services/api/routes/posts.ts

@@ -27,9 +27,13 @@ import type { CommunityShotMode, HydratedCommunityDocument } from '@/types/mongo
 import type { HydratedSettingsDocument } from '@/types/mongoose/settings';
 import type { ParamPack } from '@/types/common/param-pack';
 
+// TODO - Is this the best place to put constants like these?
+const APP_DATA_MAX_SIZE = 0x400; // * Real name is `nn::olv::APP_DATA_MAX_SIZE`
+
 const newPostSchema = z.object({
 	community_id: z.string().optional(),
-	app_data: z.string().base64().optional(),
+	// TODO - This will trigger the generic `ApiErrorCode.BAD_PARAMS` error when the size check fails, is there a specific error code for this case?
+	app_data: z.string().base64().max(APP_DATA_MAX_SIZE).refine((appData: string) => Buffer.from(appData, 'base64').length < APP_DATA_MAX_SIZE).optional(),
 	painting: z.string().base64().optional(),
 	screenshot: z.string().base64().optional(),
 	body: z.string().optional(),