iOS: NullReferenceException in HttpConnectionPool when using HttpWebRequest

[rolfbjarne]

Description

Test case:

• Checkout and build the httpclient-testcase branch of my fork of xamarin-macios (https://github.com/rolfbjarne/xamarin-macios/commits/httpclient-testcase):

git clone https://github.com/rolfbjarne/xamarin-macios
cd xamarin-macios
git checkout httpclient-testcase
./configure --enable-dotnet
make reset
make all -j8 && make install -j8

• Run the test app:

make -C tests/dotnet run-test

Result:

[...]
Unhandled Exception:
System.NullReferenceException: Object reference not set to an instance of an object
   at System.Net.Http.HttpConnectionPool..ctor(HttpConnectionPoolManager poolManager, HttpConnectionKind kind, String host, Int32 port, String sslHostName, Uri proxyUri, Int32 maxConnections)
   at System.Net.Http.HttpConnectionPoolManager.SendAsyncCore(HttpRequestMessage request, Uri proxyUri, Boolean async, Boolean doRequestAuth, Boolean isProxyConnect, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPoolManager.SendAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpMessageHandlerStage.Send(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.SocketsHttpHandler.Send(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.HttpMessageInvoker.Send(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.HttpClient.Send(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationToken cancellationToken)
   at System.Net.HttpWebRequest.SendRequest(Boolean async)
   at System.Net.HttpWebRequest.GetResponse()
   at MySingleView.AppDelegate.FinishedLaunching(UIApplication app, NSDictionary options) in /Users/rolf/work/maccore/main/xamarin-macios/tests/dotnet/MySingleView/AppDelegate.cs:line 22
--- End of stack trace from previous location ---
   at UIKit.UIApplication.Main(String[] args, IntPtr principal, IntPtr delegate)
   at UIKit.UIApplication.Main(String[] args, String principalClassName, String delegateClassName)
   at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass)
   at MySingleView.Application.Main(String[] args) in /Users/rolf/work/maccore/main/xamarin-macios/tests/dotnet/MySingleView/Main.cs:line 12

I tried reproing on desktop (https://gist.github.com/rolfbjarne/f1cb38aab4ba58b49b2ec244e45d1a70), but it worked just fine.

Regression?

Yes, this is a regression between preview.2.21114.3 and preview.2.21153.28.

CC @steveisok

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Issue Details

---

Description

Test case:

• Checkout and build the httpclient-testcase branch of my fork of xamarin-macios (https://github.com/rolfbjarne/xamarin-macios/commits/httpclient-testcase):

git clone https://github.com/rolfbjarne/xamarin-macios
cd xamarin-macios
git checkout httpclient-testcase
./configure --enable-dotnet
make reset
make all -j8 && make install -j8

• Run the test app:

make -C tests/dotnet run-test

Result:

[...]
Unhandled Exception:
System.NullReferenceException: Object reference not set to an instance of an object
   at System.Net.Http.HttpConnectionPool..ctor(HttpConnectionPoolManager poolManager, HttpConnectionKind kind, String host, Int32 port, String sslHostName, Uri proxyUri, Int32 maxConnections)
   at System.Net.Http.HttpConnectionPoolManager.SendAsyncCore(HttpRequestMessage request, Uri proxyUri, Boolean async, Boolean doRequestAuth, Boolean isProxyConnect, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPoolManager.SendAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpMessageHandlerStage.Send(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.SocketsHttpHandler.Send(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.HttpMessageInvoker.Send(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.HttpClient.Send(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationToken cancellationToken)
   at System.Net.HttpWebRequest.SendRequest(Boolean async)
   at System.Net.HttpWebRequest.GetResponse()
   at MySingleView.AppDelegate.FinishedLaunching(UIApplication app, NSDictionary options) in /Users/rolf/work/maccore/main/xamarin-macios/tests/dotnet/MySingleView/AppDelegate.cs:line 22
--- End of stack trace from previous location ---
   at UIKit.UIApplication.Main(String[] args, IntPtr principal, IntPtr delegate)
   at UIKit.UIApplication.Main(String[] args, String principalClassName, String delegateClassName)
   at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass)
   at MySingleView.Application.Main(String[] args) in /Users/rolf/work/maccore/main/xamarin-macios/tests/dotnet/MySingleView/Main.cs:line 12

I tried reproing on desktop (https://gist.github.com/rolfbjarne/f1cb38aab4ba58b49b2ec244e45d1a70), but it worked just fine.

Regression?

Yes, this is a regression between preview.2.21114.3 and preview.2.21153.28.

CC @steveisok

Author:	rolfbjarne
Assignees:	-
Labels:	area-System.Net.Http, untriaged
Milestone:	-

[marek-safar]

@karelz We don't believe this is ios specific as it crashes with "old" System.Net.HttpWebRequest.SendRequest API. Could someone investigate why is HttpConnectionPool..ctor crashing with NRE when we have nullable types enabled?

[marek-safar]

Likely duplicate of #49187

[stephentoub]

We don't believe this is ios specific

Have you seen it on any other OS?

when we have nullable types enabled

What do you mean by this? Are you referring to nullable reference types? The only thing NRT influences in a compiled binary are the attributes that are emitted; it doesn't change the IL for member bodies at all.

[marek-safar]

Have you seen it on any other OS?

I didn't try but there does not seem to be anything ios specific on the stack.

What do you mean by this?

In spot-checking HttpConnectionPool..ctor I didn't see any ! so it's a bit surprising to have no compiler warning and crash with NRE.

[stephentoub]

Are the binaries in use trimmed?

(Unrelated but regarding "so it's a bit surprising to have no compiler warning and crash with NRE"... NRT is far from perfect... it's completely possible to have no !s and still have nulls dereferenced, e.g. var arr = new string[42]; arr[0].GetHashCode(); will invoke GetHashCode on a null string. But, I don't think that's the issue here. I suspect the binaries that are in use have something iOS specific that is causing some object that should never be null to be null, potentially stemming from trimming, or maybe static cctors aren't being run at the right time, or some such thing.)

[stephentoub]

For example, @marek-safar, in #48480 you removed the System.Net.Quic build for iOS, but this method calls into that assembly:

runtime/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs

Line 122 in b76f17e

_http3Enabled = _poolManager.Settings._maxHttpVersion >= HttpVersion.Version30 && (_poolManager.Settings._quicImplementationProvider ?? QuicImplementationProviders.Default).IsSupported;

What happens in that case?

[rolfbjarne]

Here's the binlog and the .app zipped up:

msbuild.rename-extension-to-binlog.zip
MySingleView.zip

[stephentoub]

That's the problem:

[ManickaP]

I tried reproing on desktop (https://gist.github.com/rolfbjarne/f1cb38aab4ba58b49b2ec244e45d1a70), but it worked just fine.

I assumed iOS from this in the OP.