package middleware // Ported from Goji's middleware, source: // https://github.com/zenazn/goji/tree/master/web/middleware import ( "net/http" "time" ) // Unix epoch time var epoch = time.Unix(0, 0).Format(time.RFC1123) // Taken from https://github.com/mytrile/nocache var noCacheHeaders = map[string]string{ "Expires": epoch, "Cache-Control": "no-cache, private, max-age=0", "Pragma": "no-cache", "X-Accel-Expires": "0", } var etagHeaders = []string{ "ETag", "If-Modified-Since", "If-Match", "If-None-Match", "If-Range", "If-Unmodified-Since", } // NoCache is a simple piece of middleware that sets a number of HTTP headers to prevent // a router (or subrouter) from being cached by an upstream proxy and/or client. // // As per http://wiki.nginx.org/HttpProxyModule - NoCache sets: // Expires: Thu, 01 Jan 1970 00:00:00 UTC // Cache-Control: no-cache, private, max-age=0 // X-Accel-Expires: 0 // Pragma: no-cache (for HTTP/1.0 proxies/clients) func NoCache(h http.Handler) http.Handler { fn := func(w http.ResponseWriter, r *http.Request) { // Delete any ETag headers that may have been set for _, v := range etagHeaders { if r.Header.Get(v) != "" { r.Header.Del(v) } } // Set our NoCache headers for k, v := range noCacheHeaders { w.Header().Set(k, v) } h.ServeHTTP(w, r) } return http.HandlerFunc(fn) }