HttpProtocolException is not reported properly on initial HTTP/2 settings handshake failure

[antonfirsov]

There is an overlook in #71345. When the server doesn't initiate the connection with a proper SETTINGS preface, eg. responding by GOAWAY instead, the InnerException of the HttpRequestException being thrown must be a ProtocolException according to #70684.

Instead, we embed ProtocolException into further IOException-s 2 levels down in ProcessIncomingFramesAsync().

Repro:

[ConditionalFact(nameof(SupportsAlpn))]
public async Task Test()
{
    using Http2LoopbackServer server = Http2LoopbackServer.CreateServer();
    using HttpClient client = CreateHttpClient();
            
    Task<HttpResponseMessage> sendTask = client.GetAsync(server.Address);

    Http2LoopbackConnection connection = await server.AcceptConnectionAsync();
    await connection.ReadSettingsAsync();
    await connection.SendGoAway(0, ProtocolErrors.INTERNAL_ERROR);

    var ex = await Assert.ThrowsAsync<HttpRequestException>(() => sendTask);
    Assert.IsType<HttpProtocolException>(ex.InnerException); // Fails
}

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Issue Details

---

There is an overlook in #71345. When the server doesn't initiate the connection with a proper SETTINGS preface, eg. responding by GOAWAY instead, the InnerException of the HttpRequestException being thrown must be a ProtocolException according to #70684.

Instead, we embed ProtocolException into further IOException-s 2 levels down in ProcessIncomingFramesAsync().

Repro:

[ConditionalFact(nameof(SupportsAlpn))]
public async Task Test()
{
    using Http2LoopbackServer server = Http2LoopbackServer.CreateServer();
    using HttpClient client = CreateHttpClient();
            
    Task<HttpResponseMessage> sendTask = client.GetAsync(server.Address);

    Http2LoopbackConnection connection = await server.AcceptConnectionAsync();
    await connection.ReadSettingsAsync();
    await connection.SendGoAway(0, ProtocolErrors.INTERNAL_ERROR);

    var ex = await Assert.ThrowsAsync<HttpRequestException>(() => sendTask);
    Assert.IsType<HttpProtocolException>(ex.InnerException);
}

Author:	antonfirsov
Assignees:	-
Labels:	area-System.Net.Http
Milestone:	-

[CarnaViire]

Triage: this looks like something straightforward to fix. We should fix it in 8.0.