support CAS identity provider

Signed-off-by: hongming <talonwan@yunify.com>

vendor/gopkg.in/cas.v2/middleware.go

@@ -0,0 +1,30 @@
+package cas
+
+import (
+	"net/http"
+
+	"github.com/golang/glog"
+)
+
+// Handler returns a standard http.HandlerFunc, which will check the authenticated status (redirect user go login if needed)
+// If the user pass the authenticated check, it will call the h's ServeHTTP method
+func (c *Client) Handler(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if glog.V(2) {
+			glog.Infof("cas: handling %v request for %v", r.Method, r.URL)
+		}
+
+		setClient(r, c)
+
+		if !IsAuthenticated(r) {
+			RedirectToLogin(w, r)
+			return
+		}
+
+		if r.URL.Path == "/logout" {
+			RedirectToLogout(w, r)
+			return
+		}
+		h.ServeHTTP(w, r)
+	})
+}