Skip to content

image-proxy refactor redirect handling, and fix resource release #9052

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

image-proxy refactor redirect handling, and fix resource release #9052

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
227 changes: 115 additions & 112 deletions pkg/image_proxy/lib/image_proxy_service.dart
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -160,89 +160,81 @@ Future<shelf.Response> handler(shelf.Request request) async {
}
final imageUrlBytes = utf8.encode(imageUrl);

if (_constantTimeEquals(hmacSign(secret, imageUrlBytes), signature)) {
final Uri parsedImageUrl;
try {
parsedImageUrl = Uri.parse(imageUrl);
} on FormatException catch (e) {
return shelf.Response.badRequest(
body: 'Malformed proxied url $e',
headers: securityHeaders,
);
}
if (!(parsedImageUrl.isScheme('http') ||
parsedImageUrl.isScheme('https'))) {
return shelf.Response.badRequest(
body: 'Can only proxy http and https urls',
headers: securityHeaders,
);
}
if (!parsedImageUrl.isAbsolute) {
return shelf.Response.badRequest(
body: 'Can only proxy absolute urls',
headers: securityHeaders,
);
}
if (!_constantTimeEquals(hmacSign(secret, imageUrlBytes), signature)) {
return shelf.Response.unauthorized('Bad hmac', headers: securityHeaders);
}
final Uri parsedImageUrl;
try {
parsedImageUrl = Uri.parse(imageUrl);
} on FormatException catch (e) {
return shelf.Response.badRequest(
body: 'Malformed proxied url $e',
headers: securityHeaders,
);
}
if (!(parsedImageUrl.isScheme('http') ||
parsedImageUrl.isScheme('https'))) {
return shelf.Response.badRequest(
body: 'Can only proxy http and https urls',
headers: securityHeaders,
);
}
if (!parsedImageUrl.isAbsolute) {
return shelf.Response.badRequest(
body: 'Can only proxy absolute urls',
headers: securityHeaders,
);
}

int statusCode;
List<int> bytes;
String? contentType;
String? contentEncoding;
Future<
({
int statusCode,
List<int> body,
String? contentType,
String? contentEncoding,
})
>
makeRequest(Uri url, {int redirectCount = 0}) async {
stderr.writeln('Requesting $url');
if (redirectCount > 10) {
throw RedirectException('Too many redirects.');
}
final request = await client.getUrl(url);
final timeout = Timer(timeoutDelay, () {
request.abort(RequestTimeoutException('No response'));
});
HttpClientResponse? response;
try {
(statusCode, bytes, contentType, contentEncoding) = await retry(
maxDelay: timeoutDelay,
maxAttempts: isTesting ? 2 : 8,
() async {
final request = await client.getUrl(parsedImageUrl);
Timer? timeoutTimer;
void scheduleRequestTimeout() {
timeoutTimer?.cancel();
timeoutTimer = Timer(timeoutDelay, () {
request.abort(RequestTimeoutException('No response'));
});
}

request.headers.add(
'user-agent',
'Image proxy for pub.dev. See https://github.com/dart-lang/pub-dev/pkg/image-proxy. If you have any issues, contact [email protected].',
);
request.followRedirects = false;
scheduleRequestTimeout();
var response = await request.close();
var redirectCount = 0;
while (response.isRedirect) {
await response.drain();
redirectCount++;
if (redirectCount > 10) {
throw RedirectException('Too many redirects.');
}
final location = response.headers.value(
HttpHeaders.locationHeader,
);
if (location == null) {
throw RedirectException('No location header in redirect.');
}
final uri = parsedImageUrl.resolve(location);
final request = await client.getUrl(uri);

request.headers.add('user-agent', 'pub-proxy');
// Set the body or headers as desired.
request.followRedirects = false;
scheduleRequestTimeout();
response = await request.close();
}
switch (response.statusCode) {
case final int statusCode && >= 500 && < 600:
throw ServerSideException(statusCode: statusCode);
case final int statusCode && >= 300 && < 400:
throw ServerSideException(statusCode: statusCode);
}
final contentLength = response.contentLength;
if (contentLength != -1 && contentLength > maxImageSize) {
throw TooLargeException();
}
return (
response.statusCode,
request.headers.add(
'user-agent',
'Image proxy for pub.dev. See https://github.com/dart-lang/pub-dev/pkg/image-proxy. If you have any issues, contact [email protected].',
);
request.followRedirects = false;
response = await request.close();
if (response.isRedirect) {
await response.listen((_) => null).cancel();
final location = response.headers.value(HttpHeaders.locationHeader);
if (location == null) {
throw RedirectException('No location header in redirect.');
}
return makeRequest(
parsedImageUrl.resolve(location),
redirectCount: redirectCount + 1,
);
}
switch (response.statusCode) {
case final int statusCode && >= 500 && < 600:
throw ServerSideException(statusCode: statusCode);
case final int statusCode && >= 300 && < 400:
throw ServerSideException(statusCode: statusCode);
}
final contentLength = response.contentLength;
if (contentLength != -1 && contentLength > maxImageSize) {
throw TooLargeException();
}
return (
statusCode: response.statusCode,
body:
await readAllBytes(
response,
contentLength == -1 ? maxImageSize : contentLength,
Expand All @@ -252,49 +244,60 @@ Future<shelf.Response> handler(shelf.Request request) async {
throw RequestTimeoutException('No response');
},
),
response.headers.value('content-type'),
response.headers.value('content-encoding'),
);
},
retryIf: (e) =>
e is SocketException ||
e is http.ClientException ||
e is ServerSideException,
);
} on TooLargeException {
return shelf.Response.badRequest(
body: 'Image too large',
headers: securityHeaders,
);
} on RedirectException catch (e) {
return shelf.Response.badRequest(
body: e.message,
headers: securityHeaders,
);
} on RequestTimeoutException catch (e) {
return shelf.Response.badRequest(
body: e.message,
headers: securityHeaders,
);
} on ServerSideException catch (e) {
return shelf.Response.badRequest(
body: 'Failed to retrieve image. Status code ${e.statusCode}',
headers: securityHeaders,
contentType: response.headers.value('content-type'),
contentEncoding: response.headers.value('content-encoding'),
);
} finally {
timeout.cancel();
try {
// Attempt closing resources
request.abort();
await response?.listen((_) => null).cancel();
} catch (_) {}
}
}

try {
final (:statusCode, :body, :contentType, :contentEncoding) = await retry(
maxDelay: timeoutDelay,
maxAttempts: isTesting ? 2 : 8,
() => makeRequest(parsedImageUrl),
retryIf: (e) =>
e is SocketException ||
e is http.ClientException ||
e is ServerSideException,
);

return shelf.Response(
statusCode,
body: bytes,
body: body,
headers: {
'Cache-control': 'max-age=180, public',
'content-type': ?contentType,
'content-encoding': ?contentEncoding,
...securityHeaders,
},
);
} else {
return shelf.Response.unauthorized('Bad hmac', headers: securityHeaders);
} on TooLargeException {
return shelf.Response.badRequest(
body: 'Image too large',
headers: securityHeaders,
);
} on RedirectException catch (e) {
return shelf.Response.badRequest(
body: e.message,
headers: securityHeaders,
);
} on RequestTimeoutException catch (e) {
return shelf.Response.badRequest(
body: e.message,
headers: securityHeaders,
);
} on ServerSideException catch (e) {
return shelf.Response.badRequest(
body: 'Failed to retrieve image. Status code ${e.statusCode}',
headers: securityHeaders,
);
}
} catch (e, st) {
stderr.writeln('Uncaught error: $e $st');
Expand Down