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