🔒 feat: Implement Granular File Storage Strategies and Access Control Middleware

api/server/utils/getFileStrategy.js

@@ -0,0 +1,61 @@
+const { FileContext } = require('librechat-data-provider');
+
+/**
+ * Determines the appropriate file storage strategy based on file type and configuration.
+ *
+ * @param {Object} config - App configuration object containing fileStrategy and fileStrategies
+ * @param {Object} options - File context options
+ * @param {boolean} options.isAvatar - Whether this is an avatar upload
+ * @param {boolean} options.isImage - Whether this is an image upload
+ * @param {string} options.context - File context from FileContext enum
+ * @returns {string} Storage strategy to use (e.g., 'local', 's3', 'azure')
+ *
+ * @example
+ * // Legacy single strategy
+ * getFileStrategy({ fileStrategy: 's3' }) // Returns 's3'
+ *
+ * @example
+ * // Granular strategies
+ * getFileStrategy(
+ *   {
+ *     fileStrategy: 's3',
+ *     fileStrategies: { avatar: 'local', document: 's3' }
+ *   },
+ *   { isAvatar: true }
+ * ) // Returns 'local'
+ */
+function getFileStrategy(appLocals, { isAvatar = false, isImage = false, context = null } = {}) {
+  // Handle both old (config object) and new (app.locals object) calling patterns
+  const isAppLocals = appLocals.fileStrategy !== undefined;
+  const config = isAppLocals ? appLocals.config : appLocals;
+  const fileStrategy = isAppLocals ? appLocals.fileStrategy : appLocals.fileStrategy;
+
+  // Fallback to legacy single strategy if no granular config
+  if (!config?.fileStrategies) {
+    return fileStrategy || 'local'; // Default to 'local' if undefined
+  }
+
+  const strategies = config.fileStrategies;
+  const defaultStrategy = strategies.default || fileStrategy || 'local';
+
+  // Priority order for strategy selection:
+  // 1. Specific file type strategy
+  // 2. Default strategy from fileStrategies
+  // 3. Legacy fileStrategy
+  // 4. 'local' as final fallback
+
+  let selectedStrategy;
+
+  if (isAvatar || context === FileContext.avatar) {
+    selectedStrategy = strategies.avatar || defaultStrategy;
+  } else if (isImage || context === FileContext.image_generation) {
+    selectedStrategy = strategies.image || defaultStrategy;
+  } else {
+    // All other files (documents, attachments, etc.)
+    selectedStrategy = strategies.document || defaultStrategy;
+  }
+
+  return selectedStrategy || 'local'; // Final fallback to 'local'
+}
+
+module.exports = { getFileStrategy };