Support ASP.NET Core 3.0

[martincostello]

Adds support for ASP.NET Core 3.0 to various simple all providers.

So far, this PR has only updated providers that had one explicit usage of Newtonsoft.Json. All others have been left targeting .NET Core 2.0 for now.

There's lots of #if and copied code here - I'm sure there's a better way it could be factored.

Relates to #275.

[kevinchalet]

Thanks for your PR!

It looks good but let's just get rid of the netstandard20 TFM: ASP.NET Core 3.0 will be .NET Core-only so there's no point trying to support .NET Standard (and having 2 TFM that target different versions is a terrible recipe for a disaster 😅)

[martincostello]

Great, that’s much easier. I assumed you’d want to keep both so fixed could be back-ported to 2.0 users, but if that’s not a problem than that makes this much easier 😃

[martincostello]

This should be mostly functional for ASP.NET Core 3.0 now, based on preview 3. I can't test all the providers, but most are simple migrations based on dotnet/aspnetcore#7105.

However, there's four bits that need further review:

1. Adding the email to the payload for VKontakte:

   AspNet.Security.OAuth.Providers/src/AspNet.Security.OAuth.Vkontakte/VkontakteAuthenticationHandler.cs

   Lines 67 to 68 in 24f5483

   	// TODO Work out the best way to achieve this with System.Text.Json
   	////payload.Add("email", tokenEmail);

2. Determine the best way to copy the tokens for Yammer:

   AspNet.Security.OAuth.Providers/src/AspNet.Security.OAuth.Yammer/YammerAuthenticationHandler.cs

   Lines 102 to 109 in 24f5483

   	// HACK Work out the best way to do this with System.Text.Json
   	using (var stream = new MemoryStream())
   	{
   	WriteAccessToken(accessToken, stream);
   	var copy = JsonDocument.Parse(stream);
   	return OAuthTokenResponse.Success(copy);
   	}

3. Determine the best way to copy the tokens for StackExchange:

   AspNet.Security.OAuth.Providers/src/AspNet.Security.OAuth.StackExchange/StackExchangeAuthenticationHandler.cs

   Lines 102 to 109 in 24f5483

   	// HACK Work out the best way to do this with System.Text.Json
   	using (var stream = new MemoryStream())
   	{
   	CopyPayload(content, stream);
   	var copy = JsonDocument.Parse(stream);
   	return OAuthTokenResponse.Success(copy);
   	}

4. Determine the best way to copy the tokens for QQ:

   AspNet.Security.OAuth.Providers/src/AspNet.Security.OAuth.QQ/QQAuthenticationHandler.cs

   Lines 118 to 125 in 24f5483

   	// HACK Work out the best way to do this with System.Text.Json
   	using (var stream = new MemoryStream())
   	{
   	CopyPayload(content, stream);
   	var payload = JsonDocument.Parse(stream);
   	return OAuthTokenResponse.Success(payload);
   	}

[martincostello]

I've tested the updated Amazon authentication handler with the 3.0 branch of my site (martincostello/alexa-london-travel-site#255), and things are working as expected.

[niltor]

When it can be updated to nuget?

[kevinchalet]

However, there's four bits that need further review.

/cc @Tratcher @ahsonkhan could you please shed some light on this?

When it can be updated to nuget?

We'll likely make them available via the MyGet.org feed but I wouldn't expect a public release (i.e on NuGet.org) before 3.0 general availability.

[martincostello]

@PinpointTownes FYI I’m working on a separate PR that I’ll submit for separate review at the weekend to add some integration tests for a couple of the providers as a proof-of-concept. If that’s acceptable when I submit it I’ll add it to this PR so we’re confident the changes are all working as I can only easily test the Amazon one myself.

[martincostello]

Draft tests PR for review opened in #282.

[martincostello]

Excluding any code improvements that could be made as referenced by my earlier #280 (comment), I believe this PR is now feature complete.

[martincostello]

Thanks for the review @Tratcher @bartonjs, I’ll push up some changes tomorrow.

[martincostello]

@Tratcher I've updated the hacky "copy" code to use some of the new preview 5 APIs in 9a80d10. If you get some time, could you take a quick look to check that the approach is a valid usage of the new bits?

[Tratcher]

Looks cleaner. @BrennanConroy?

[kevinchalet]

@Tratcher are there plans to eventually add less hackish APIs to support creating JSON constructs without a backing array (a-la JObject)?

I hate to be that guy, but I'm sure that System.Xml.Linq (and even System.Xml 😅) currently offer a better experience for these scenarios.

[BrennanConroy]

Yeah looks good.

[martincostello]

@Tratcher @BrennanConroy Thanks both.

[Tratcher]

@PinpointTownes I completely agree and have given the Json folks that feedback.

The other possibility here is that this isn't the right datatype to expose in the API, we should have used something more abstract that you could implement using a JsonDocument or your own underlying structure. I hesitate to invent a new abstraction though, and I wouldn't want to use an existing one like nested IDictionary<string, object>. Open to suggestions.

[martincostello]

Need to fix this either now or when preview 6 arrives: dotnet/aspnetcore#10615 (comment)

[martincostello]

@PinpointTownes This PR is getting quite large and unwieldy now, and there's still at least 2 more previews to go until RTM. I was thinking about creating a dev/3.0.0 branch off master, re-targeting this PR to it and then merging.

Then I can do PRs for each preview into that branch until 3.0 ships, and then do a final squash PR back to dev when the time comes. The added benefit of that approach is that 3.0 preview supporting packages get published to MyGet.

Thoughts?

[kevinchalet]

Do you still expect major changes in the 2.x packages? If not, we should probably simply merge this PR into dev and forget about 2.x stuff. If we need to release patches, we can simply use the 2.1.0 tag and create a new patch branch from there.

[martincostello]

I'm bit wary about making the main dev branch be against a preview version, rather than a stable one.

Otherwise it might discourage the community from submitting new providers as they'd have to work against preview API surfaces they might not know as much about (e.g. the new JSON stuff) for the next 4 months until 3.0 RTM lands.