providers: add okta

[abraithwaite]

No description provided.

[abraithwaite]

I think this is what #284 is referring to.

[ploxiln]

It would be better for this to be in a separate PR, not mixed in with this one.

[abraithwaite]

Could still use some tests. Lemme know if you have any specific rules about contributing and I'm happy to comply.

[Fodoj]

This is very much needed!

[statik]

See issue #428

[asms]

@abraithwaite Validation does not work. Specifically request to /oauth2/v1/userinfo returns a 400 Bad Request. The reason is that the access_token is passed as a GET argument (i.e. /oauth2/v1/userinfo?access_token=...) rather than using the Authorization: Bearer ... header. At a glance, it seems like ValidateSessionState needs to be implemented. See the facebook provider for an example:

oauth2_proxy/providers/facebook.go

Lines 78 to 80 in a9c55bd

	func (p *FacebookProvider) ValidateSessionState(s *SessionState) bool {
	return validateToken(p, s.AccessToken, getFacebookHeader(s.AccessToken))
	}

2017/08/30 13:44:30 internal_util.go:67: 400 GET https://[REDACTED].okta.com/oauth2/v1/userinfo?access_token=[REDACTED]... {}

[abraithwaite]

Thanks. I'll try and look at it when I have time, otherwise if someone else beats me to it please close this PR!

[rothgar]

Commenting here to show support for this and follow updates

[rothgar]

I got this built but having trouble setting up the okta side of the application for testing. I think I'm not setting up my login redirect URI properly but if someone has an example it'd be helpful.
My requests are redirecting properly but I'm getting this on Okta

I see the request redirect to GET - "/oauth2/start?rd=%2F" HTTP/1.0 but I still receive a 400 from okta.

[reedloden]

Since I can't edit this PR directly, opened #528.

[abraithwaite]

Neat! Been waiting to close this. Thanks!