Integrate an OAuth provider (server-side)

[hsluoyz]

Casdoor acts like both a OAuth client and OAuth server:

1. For the Casdoor user applications (e.g., a forum or a blog system that uses Casdoor to manager login and permissions), Casdoor will behave as the OAuth service providers.
2. For real 3rd-party identity providers like Gmail, Google, WeChat, Casdoor will act as an OAuth client.

We need to choose which lib in Golang for both OAuth client and server-side.

[uran0sH]

golang/oauth2 could serve as OAuth client. https://godoc.org/golang.org/x/oauth2#example-Config shows how to config.
go-oauth2/oauth2 could serve as an OAuth server-side. https://github.com/go-oauth2/oauth2/tree/master/example shows how to use it.

[hsluoyz]

@RobotHuang why is WeChat special? If it is following official OAuth standard, then any one of OAuth servers can support it, right?

[uran0sH]

@hsluoyz I meant that golang/oauth2 doesn't include WeChat endpoint now. I read the source code of golang/oauth2 and find that it is easy to add other endpoints.
https://godoc.org/golang.org/x/oauth2#example-Config shows how to add a new endpoint.

[hsluoyz]

@RobotHuang why https://github.com/golang/oauth2 contains OAuth server? It said:

[uran0sH]

@hsluoyz Sorry, it is my mistake. It could only be used as client.