npgsql: Read with timeout is incompatible with SslStream

As @Emill wrote in gitter, our current synchronous implementation of Wait() will fail if a timeout is passed and SslStream is used, because:

SslStream assumes that a timeout along with any other IOException when one is thrown from the inner stream will be treated as fatal by its caller. Reusing a SslStream instance after a timeout will return garbage. An application should Close the SslStream and throw an exception in these cases.

See http://stackoverflow.com/questions/37177401/how-to-repeatedly-read-from-net-sslstream-with-a-timeout.

Note sure if there’s a good workaround for SslStream. For now, adding a check that throws NotSupportedException.

About this issue

Original URL
State: closed
Created 7 years ago
Comments: 22 (22 by maintainers)

Commits related to this issue

Add check for wait with timeout + SSL https://github.com/npgsql/npgsql/issues/1501 — committed to npgsql/npgsql by roji 7 years ago
Fix check for wait with timeout + SSL #1501 — committed to cladisch/npgsql by cladisch 4 years ago
Fix check for wait with timeout + SSL #1501 — committed to npgsql/npgsql by cladisch 4 years ago
Fix check for wait with timeout + SSL #1501 (cherry picked from commit 572918fc3a94cf201ba947dac341d1a1de38f7b9) — committed to npgsql/npgsql by cladisch 4 years ago
Fix check for wait with timeout + SSL #1501 (cherry picked from commit 572918fc3a94cf201ba947dac341d1a1de38f7b9) — committed to npgsql/npgsql by cladisch 4 years ago

Most upvoted comments

I agree. We can just let it do the timeout on netstandard2.0 (i.e. not block it), and if the user is on .NET Framework it’s their problem…

roji on Sep 25, 2020

Well then… great! So I guess just conditionally-compile the check for net461?

roji on Sep 24, 2020

I would also assume that it doesn’t work on .NET Core 3.1 because of dotnet/runtime#22496

It actually does work - results.

[Test]
public void WaitWithSsl()
{
	var csb = new NpgsqlConnectionStringBuilder(ConnectionString)
	{
		SslMode = SslMode.Require,
		TrustServerCertificate = true,
	};
	using (var conn = OpenConnection(csb.ToString()))
	{
		conn.ExecuteNonQuery("LISTEN notifytest");
		Assert.That(conn.Wait(1000), Is.EqualTo(false));
		Assert.That(conn.ExecuteScalar("SELECT 1"), Is.EqualTo(1));
	}
}

vonzshik on Sep 24, 2020

Oh, very good! If it also works for .NET 3.1 we could just close this issue because .NET Framework is on the way to a graveyard.

I think we can just conditional-compile the check to only throw for TFMs where the timeout doesn’t work (i.e. net461).

roji on Sep 24, 2020