Adds FetchTrustedSourcesOperation

AltStore/Operations/FetchTrustedSourcesOperation.swift

@@ -0,0 +1,57 @@
+//
+//  FetchTrustedSourcesOperation.swift
+//  AltStore
+//
+//  Created by Riley Testut on 4/13/22.
+//  Copyright © 2022 Riley Testut. All rights reserved.
+//
+
+import Foundation
+
+private extension URL
+{
+    #if STAGING
+    static let trustedSources = URL(string: "https://f000.backblazeb2.com/file/altstore-staging/altstore/trustedsources.json")!
+    #else
+    static let trustedSources = URL(string: "https://cdn.altstore.io/file/altstore/altstore/trustedsources.json")!
+    #endif
+}
+
+extension FetchTrustedSourcesOperation
+{
+    struct TrustedSource: Decodable
+    {
+        var identifier: String
+        var sourceURL: URL?
+    }
+    
+    private struct Response: Decodable
+    {
+        var version: Int
+        var sources: [FetchTrustedSourcesOperation.TrustedSource]
+    }
+}
+
+class FetchTrustedSourcesOperation: ResultOperation<[FetchTrustedSourcesOperation.TrustedSource]>
+{
+    override func main()
+    {
+        super.main()
+        
+        let dataTask = URLSession.shared.dataTask(with: .trustedSources) { (data, response, error) in
+            do
+            {
+                guard let data = data else { throw error! }
+                
+                let response = try Foundation.JSONDecoder().decode(Response.self, from: data)
+                self.finish(.success(response.sources))
+            }
+            catch
+            {
+                self.finish(.failure(error))
+            }
+        }
+        
+        dataTask.resume()
+    }
+}