Activity.Baggage is url encoded when using HttpClient but not url decoded when read by AspNetCore host

[theggelund]

Describe the bug

When calling an AspNetCore service with HttpClient and activity has any baggage, all the entries are url encoded and added to Correlation-Context http header. When the service receives the request and reads the Correlation-Context header the keys and values are not url decoded.

Also, according to this description only the value should be value should be url encoded.
Correlation Context

The code that does not url decode is here HostingApplicationDiagnostics.cs

To Reproduce

class Program
    {
        static async Task Main(string[] args)
        {
            Activity.DefaultIdFormat = ActivityIdFormat.W3C;
            DiagnosticListener.AllListeners.Subscribe(new Listener());

            string baggage = string.Empty;

            await new HostBuilder()
                .ConfigureWebHost(webHost =>
                {
                    webHost
                        .UseKestrel(opt => opt.Listen(IPAddress.Loopback, 55555))
                        .Configure(app =>
                        {
                            app.Run(async ctx =>
                            {
                                baggage = string.Join(";",
                                    Activity.Current.Baggage.Select(entry => $"{entry.Key}:{entry.Value}"));
                                
                                await ctx.Response.WriteAsync("Hello World");
                            });
                        });
                })
                .StartAsync();

            var activity = new Activity("Call server");

            string key = "env";
            string value = "+-%/";
            
            activity.AddBaggage(key, value);
            activity.Start();
            
            var client = new HttpClient(new HttpClientHandler());
            await client.GetStringAsync("http://localhost:55555/test");

            if (!baggage.Contains($"{key}={value}"))
            {
                Console.Error.WriteLine("This should have worked => " + baggage);
            }
        }
    }

    class Listener : IObserver<DiagnosticListener>, IObserver<KeyValuePair<string, object>>
    {
        public void OnCompleted() { }

        public void OnError(Exception error) { }

        public void OnNext(KeyValuePair<string, object> value) { }

        public void OnNext(DiagnosticListener value)
        {
            value.Subscribe(this);
        }
    }

csproj

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>netcoreapp3.1</TargetFramework>
    </PropertyGroup>

    <ItemGroup>
      <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="3.1.1" />
    </ItemGroup>

</Project>

Further technical details

• ASP.NET Core version
  3.1.1
• Include the output of dotnet --info
  .NET Core SDK (reflecting any global.json):
  Version: 3.1.101
  Commit: b377529961

Runtime Environment:
OS Name: Windows
OS Version: 10.0.18363
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\3.1.101\

Host (useful for support):
Version: 3.1.1
Commit: a1388f194c

.NET Core SDKs installed:
3.1.101 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.15 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
https://aka.ms/dotnet-download

[analogrelay]

Seems like a legit bug.

[vaughanr]

Hi, I attempted to fix this in a pull request above. I only url decoded the baggage value based on the spec in the link that @theggelund supplied. It would be trivial to do the same with the key if the fact that the key is url encoded is expected behavior. Please let me know if I need to make any changes?

[JunTaoLuo]

Thanks for the contribution!