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Hide main method with option to skip local network check + local test.
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// Copyright 2023 Google LLC | ||
// | ||
// Licensed under the Apache License, Version 2.0 (the "License"); | ||
// you may not use this file except in compliance with the License. | ||
// You may obtain a copy of the License at | ||
// | ||
// https://www.apache.org/licenses/LICENSE-2.0 | ||
// | ||
// Unless required by applicable law or agreed to in writing, software | ||
// distributed under the License is distributed on an "AS IS" BASIS, | ||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
// See the License for the specific language governing permissions and | ||
// limitations under the License. | ||
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import 'dart:io'; | ||
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import 'package:retry/retry.dart'; | ||
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import 'private_ip.dart'; | ||
import 'unique_local_ip.dart'; | ||
import 'version.dart'; | ||
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const defaultUserAgent = 'package:safe_url_check/$packageVersion ' | ||
'(+https://github.com/google/dart-neats/tree/master/safe_url_check)'; | ||
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Future<bool> doSafeUrlCheck( | ||
Uri url, { | ||
int maxRedirects = 8, | ||
String userAgent = defaultUserAgent, | ||
HttpClient? client, | ||
RetryOptions retryOptions = const RetryOptions(maxAttempts: 3), | ||
Duration timeout = const Duration(seconds: 90), | ||
}) async { | ||
ArgumentError.checkNotNull(url, 'url'); | ||
ArgumentError.checkNotNull(maxRedirects, 'maxRedirects'); | ||
ArgumentError.checkNotNull(userAgent, 'userAgent'); | ||
ArgumentError.checkNotNull(retryOptions, 'retryOptions'); | ||
if (maxRedirects < 0) { | ||
throw ArgumentError.value( | ||
maxRedirects, | ||
'maxRedirects', | ||
'must be a positive integer', | ||
); | ||
} | ||
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try { | ||
// Create client if one wasn't given. | ||
var c = client; | ||
c ??= HttpClient(); | ||
try { | ||
return await SafeUrlChecker( | ||
client: c, | ||
userAgent: userAgent, | ||
retryOptions: retryOptions, | ||
timeout: timeout, | ||
).checkUrl(url, maxRedirects); | ||
} finally { | ||
// Close client, if it was created here. | ||
if (client == null) { | ||
c.close(force: true); | ||
} | ||
} | ||
} on Exception { | ||
return false; | ||
} | ||
} | ||
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class SafeUrlChecker { | ||
final HttpClient client; | ||
final String userAgent; | ||
final RetryOptions retryOptions; | ||
final Duration timeout; | ||
final bool skipLocalNetworkCheck; | ||
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SafeUrlChecker({ | ||
required this.client, | ||
required this.userAgent, | ||
required this.retryOptions, | ||
required this.timeout, | ||
this.skipLocalNetworkCheck = false, | ||
}); | ||
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Future<bool> checkUrl( | ||
Uri url, | ||
int maxRedirects, | ||
) async { | ||
assert(maxRedirects >= 0); | ||
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// If no scheme or not http or https, we fail. | ||
if (!url.hasScheme || (!url.isScheme('http') && !url.isScheme('https'))) { | ||
return false; | ||
} | ||
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final ips = await retryOptions.retry(() async { | ||
final ips = await InternetAddress.lookup(url.host).timeout(timeout); | ||
if (ips.isEmpty) { | ||
throw Exception('DNS resolution failed'); | ||
} | ||
return ips; | ||
}); | ||
if (!skipLocalNetworkCheck) { | ||
for (final ip in ips) { | ||
// If given a loopback, linklocal or multicast IP, return false | ||
if (ip.isLoopback || | ||
ip.isLinkLocal || | ||
ip.isMulticast || | ||
isPrivateIpV4(ip) || | ||
isUniqueLocalIpV6(ip)) { | ||
return false; | ||
} | ||
} | ||
} | ||
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final response = await retryOptions.retry(() async { | ||
// We can't use the HttpClient from dart:io with a custom socket, so instead | ||
// of making a connection to one of the IPs resolved above, and specifying | ||
// the host header, we rely on the OS caching DNS queries and not returning | ||
// different IPs for a second lookup. | ||
final request = await client.headUrl(url).timeout(timeout); | ||
request.followRedirects = false; | ||
request.headers.set(HttpHeaders.userAgentHeader, userAgent); | ||
final response = await request.close().timeout(timeout); | ||
await response.drain().catchError((e) => null).timeout(timeout); | ||
if (500 <= response.statusCode && response.statusCode < 600) { | ||
// retry again, when we hit a 5xx response | ||
throw Exception('internal server error'); | ||
} | ||
return response; | ||
}); | ||
if (200 <= response.statusCode && response.statusCode < 300) { | ||
return true; | ||
} | ||
if (response.isRedirect && | ||
response.headers[HttpHeaders.locationHeader]!.isNotEmpty && | ||
maxRedirects > 0) { | ||
final loc = Uri.parse(response.headers[HttpHeaders.locationHeader]![0]); | ||
final nextUri = url.resolveUri(loc); | ||
return checkUrl(nextUri, maxRedirects - 1); | ||
} | ||
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// Response is 4xx, or some other unsupported code. | ||
return false; | ||
} | ||
} |
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// Copyright 2023 Google LLC | ||
// | ||
// Licensed under the Apache License, Version 2.0 (the "License"); | ||
// you may not use this file except in compliance with the License. | ||
// You may obtain a copy of the License at | ||
// | ||
// https://www.apache.org/licenses/LICENSE-2.0 | ||
// | ||
// Unless required by applicable law or agreed to in writing, software | ||
// distributed under the License is distributed on an "AS IS" BASIS, | ||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
// See the License for the specific language governing permissions and | ||
// limitations under the License. | ||
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import 'dart:io'; | ||
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import 'package:retry/retry.dart'; | ||
import 'package:safe_url_check/src/safe_url_check.dart'; | ||
import 'package:test/test.dart'; | ||
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void main() { | ||
late HttpServer server; | ||
setUpAll(() async { | ||
server = await HttpServer.bind(InternetAddress.anyIPv4, 0); | ||
server.listen((e) async { | ||
switch (e.requestedUri.path) { | ||
case '/redirect/local': | ||
e.response.statusCode = 303; | ||
e.response.headers.set('location', 'target'); | ||
await e.response.close(); | ||
return; | ||
case '/redirect/target': | ||
e.response.write('OK'); | ||
await e.response.close(); | ||
return; | ||
default: | ||
e.response.statusCode = 404; | ||
await e.response.close(); | ||
} | ||
}); | ||
}); | ||
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tearDownAll(() async { | ||
await server.close(); | ||
}); | ||
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test('relative redirect', () async { | ||
final client = HttpClient(); | ||
final checker = SafeUrlChecker( | ||
client: client, | ||
userAgent: defaultUserAgent, | ||
retryOptions: RetryOptions(), | ||
timeout: Duration(seconds: 2), | ||
skipLocalNetworkCheck: true, | ||
); | ||
expect( | ||
await checker.checkUrl( | ||
Uri.parse('http://localhost:${server.port}/redirect/local'), 2), | ||
isTrue); | ||
}); | ||
} |