1 files changed, 16 insertions, 2 deletions
diff --git a/server/auth/provider.go b/server/auth/provider.go
index 06dc1c9..d4a8e58 100644
--- a/server/auth/provider.go
+++ b/server/auth/provider.go
@@ -1,11 +1,16 @@
 package auth
 
-import "golang.org/x/oauth2"
+import (
+	"fmt"
+	"net/http"
+
+	"golang.org/x/oauth2"
+)
 
 // Provider is an abstraction of different auth methods.
 type Provider interface {
 	Name() string
-	StartSession(string) *Session
+	StartSession(string, *http.Request) *Session
 	Exchange(string) (*oauth2.Token, error)
 	Username(*oauth2.Token) string
 	Valid(*oauth2.Token) bool
@@ -28,3 +33,12 @@ func (s *Session) Authorize(provider Provider, code string) error {
 	s.Token = t
 	return nil
 }
+
+// Oauth2RedirectURL returns an OAuth redirect_uri for this request.
+func Oauth2RedirectURL(r *http.Request) string {
+	protocol := "http"
+	if r.TLS != nil {
+		protocol = "https"
+	}
+	return fmt.Sprintf("%s://%s/auth/callback", protocol, r.Host)
+}