// Copyright 2015 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'dart:async'; import '../base/context.dart'; import '../globals.dart'; import 'common.dart'; import 'io.dart'; const int kNetworkProblemExitCode = 50; typedef HttpClientFactory = HttpClient Function(); /// Download a file from the given URL and return the bytes. Future<List<int>> fetchUrl(Uri url) async { int attempts = 0; int duration = 1; while (true) { attempts += 1; final List<int> result = await _attempt(url); if (result != null) return result; printStatus('Download failed -- attempting retry $attempts in $duration second${ duration == 1 ? "" : "s"}...'); await Future<void>.delayed(Duration(seconds: duration)); if (duration < 64) duration *= 2; } } /// Check if the given URL points to a valid endpoint. Future<bool> doesRemoteFileExist(Uri url) async => (await _attempt(url, onlyHeaders: true)) != null; Future<List<int>> _attempt(Uri url, { bool onlyHeaders = false }) async { printTrace('Downloading: $url'); HttpClient httpClient; if (context[HttpClientFactory] != null) { httpClient = (context[HttpClientFactory] as HttpClientFactory)(); // ignore: avoid_as } else { httpClient = HttpClient(); } HttpClientRequest request; try { if (onlyHeaders) { request = await httpClient.headUrl(url); } else { request = await httpClient.getUrl(url); } } on HandshakeException catch (error) { printTrace(error.toString()); throwToolExit( 'Could not authenticate download server. You may be experiencing a man-in-the-middle attack,\n' 'your network may be compromised, or you may have malware installed on your computer.\n' 'URL: $url', exitCode: kNetworkProblemExitCode, ); } on SocketException catch (error) { printTrace('Download error: $error'); return null; } final HttpClientResponse response = await request.close(); // If we're making a HEAD request, we're only checking to see if the URL is // valid. if (onlyHeaders) { return (response.statusCode == 200) ? <int>[] : null; } if (response.statusCode != 200) { if (response.statusCode > 0 && response.statusCode < 500) { throwToolExit( 'Download failed.\n' 'URL: $url\n' 'Error: ${response.statusCode} ${response.reasonPhrase}', exitCode: kNetworkProblemExitCode, ); } // 5xx errors are server errors and we can try again printTrace('Download error: ${response.statusCode} ${response.reasonPhrase}'); return null; } printTrace('Received response from server, collecting bytes...'); try { final BytesBuilder responseBody = BytesBuilder(copy: false); await response.forEach(responseBody.add); return responseBody.takeBytes(); } on IOException catch (error) { printTrace('Download error: $error'); return null; } }