gRPC conversions - SSO Auth Connectors

[Joerger]

Converts the following http endpoints to gRPC:

• CreateOIDCAuthRequest
• CreateSAMLAuthRequest
• CreateGithubAuthRequest
• GetOIDCAuthRequest
• GetSAMLAuthRequest
• GetGithubAuthRequest
• GetSSODiagnosticInfo

Since the last 4 endpoints are brand new and are being released in v10, they do not need http fallback logic.

See #12783 (comment) for motivation behind this PR.

e PR - https://github.com/gravitational/teleport.e/pull/458

Updates #6394

[Tener]

Thank you for this @Joerger, this set of changes is even larger than I expected it to be. It looks good though.

Some unit tests are failing, but this is easily fixable stuff:

--- FAIL: TestSSODiagnosticInfo (2.19s)
panic: invalid Go type *types.AssertionInfo for field types.SSODiagnosticInfo.SAMLAssertionInfo [recovered]
	panic: invalid Go type *types.AssertionInfo for field types.SSODiagnosticInfo.SAMLAssertionInfo

[strideynet]

Looks good just one concern.

[rosstimothy]

I think this breaks backward compatibility. I'm unable to login via GitHub when running v10 auth and v9.3.6 proxy.

2022-06-16T10:30:47-04:00 ERRO [WEB]       Error creating auth request. auth:github error:[
ERROR REPORT:
Original Error: *trace.BadParameterError request: json: cannot unmarshal number into Go value of type string
Stack Trace:

Caught:
	/private/tmp/build-darwin-amd64/go/src/github.com/gravitational/teleport/lib/httplib/httplib.go:155 github.com/gravitational/teleport/lib/httplib.ConvertResponse
	/private/tmp/build-darwin-amd64/go/src/github.com/gravitational/teleport/lib/auth/clt.go:278 github.com/gravitational/teleport/lib/auth.(*Client).PostJSON
	/private/tmp/build-darwin-amd64/go/src/github.com/gravitational/teleport/lib/auth/clt.go:1244 github.com/gravitational/teleport/lib/auth.(*Client).CreateGithubAuthRequest
	/private/tmp/build-darwin-amd64/go/src/github.com/gravitational/teleport/lib/web/apiserver.go:1063 github.com/gravitational/teleport/lib/web.(*Handler).githubLoginWeb
	/private/tmp/build-darwin-amd64/go/src/github.com/gravitational/teleport/lib/web/apiserver.go:2551 github.com/gravitational/teleport/lib/web.(*Handler).WithRedirect.func1
	/tmp/build-darwin-amd64/go/pkg/mod/github.com/gravitational/httprouter@v1.3.1-0.20220408074523-c876c5e705a5/router.go:399 github.com/julienschmidt/httprouter.(*Router).ServeHTTP
	/var/folders/ys/8czjjsys38x504kj8172pd_m0000gp/T/drone-MH8sayoNWmwkJaEN/home/drone/build-12784-1655249166-toolchains/go/src/net/http/server.go:2090 net/http.StripPrefix.func1
	/var/folders/ys/8czjjsys38x504kj8172pd_m0000gp/T/drone-MH8sayoNWmwkJaEN/home/drone/build-12784-1655249166-toolchains/go/src/net/http/server.go:2047 net/http.HandlerFunc.ServeHTTP
	/private/tmp/build-darwin-amd64/go/src/github.com/gravitational/teleport/lib/web/apiserver.go:454 github.com/gravitational/teleport/lib/web.NewHandler.func1
	/var/folders/ys/8czjjsys38x504kj8172pd_m0000gp/T/drone-MH8sayoNWmwkJaEN/home/drone/build-12784-1655249166-toolchains/go/src/net/http/server.go:2047 net/http.HandlerFunc.ServeHTTP
	/tmp/build-darwin-amd64/go/pkg/mod/github.com/gravitational/httprouter@v1.3.1-0.20220408074523-c876c5e705a5/router.go:460 github.com/julienschmidt/httprouter.(*Router).ServeHTTP
	/private/tmp/build-darwin-amd64/go/src/github.com/gravitational/teleport/lib/web/apiserver.go:215 github.com/gravitational/teleport/lib/web.(*APIHandler).ServeHTTP
	/tmp/build-darwin-amd64/go/pkg/mod/github.com/gravitational/oxy@v0.0.0-20211213172937-a1ba0900a4c9/ratelimit/tokenlimiter.go:118 github.com/gravitational/oxy/ratelimit.(*TokenLimiter).ServeHTTP
	/tmp/build-darwin-amd64/go/pkg/mod/github.com/gravitational/oxy@v0.0.0-20211213172937-a1ba0900a4c9/connlimit/connlimit.go:75 github.com/gravitational/oxy/connlimit.(*ConnLimiter).ServeHTTP
	/var/folders/ys/8czjjsys38x504kj8172pd_m0000gp/T/drone-MH8sayoNWmwkJaEN/home/drone/build-12784-1655249166-toolchains/go/src/net/http/server.go:2879 net/http.serverHandler.ServeHTTP
	/var/folders/ys/8czjjsys38x504kj8172pd_m0000gp/T/drone-MH8sayoNWmwkJaEN/home/drone/build-12784-1655249166-toolchains/go/src/net/http/server.go:3480 net/http.initALPNRequest.ServeHTTP
	/var/folders/ys/8czjjsys38x504kj8172pd_m0000gp/T/drone-MH8sayoNWmwkJaEN/home/drone/build-12784-1655249166-toolchains/go/src/net/http/h2_bundle.go:5849 net/http.(*http2serverConn).runHandler
	/var/folders/ys/8czjjsys38x504kj8172pd_m0000gp/T/drone-MH8sayoNWmwkJaEN/home/drone/build-12784-1655249166-toolchains/go/src/runtime/asm_amd64.s:1581 runtime.goexit
User Message: request: json: cannot unmarshal number into Go value of type string
] web/apiserver.go:1071

This looks to be caused by casting the CertTTL to a types.Duration:

teleport/api/types/types.proto

Lines 2714 to 2715 in 78c1450

	// CertTTL is the TTL of the certificate user wants to get
	int64 CertTTL = 8 [ (gogoproto.jsontag) = "cert_ttl", (gogoproto.casttype) = "Duration" ];

The custom marshalling/unmarshalling is expecting to be working with a string which is no longer the case

teleport/api/types/duration.go

Lines 48 to 66 in 78c1450

	func (d *Duration) UnmarshalJSON(data []byte) error {
	if len(data) == 0 {
	return nil
	}
	var stringVar string
	if err := json.Unmarshal(data, &stringVar); err != nil {
	return trace.Wrap(err)
	}
	if stringVar == constants.DurationNever {
	*d = Duration(0)
	return nil
	}
	out, err := parseDuration(stringVar)
	if err != nil {
	return trace.BadParameter(err.Error())
	}
	*d = out
	return nil
	}