Merge branch 'feat/no-cache' into 'master'

[feat] nocache

See merge request leap/getmyip!6

2 files changed, 59 insertions, 1 deletions

diff --git a/main.go b/main.go
index aa57c86..e883834 100644
--- a/main.go
+++ b/main.go
@@ -254,7 +254,7 @@ func main() {
 	bonafide.listGateways()
 
 	mux := http.NewServeMux()
-	jh := &jsonHandler{&geoipdb}
+	jh := noCache(&jsonHandler{&geoipdb})
 	mux.Handle("/json", jh)
 
 	th := &txtHandler{&geoipdb}
diff --git a/nocache.go b/nocache.go
new file mode 100644
index 0000000..cad8393
--- /dev/null
+++ b/nocache.go
@@ -0,0 +1,58 @@
+package main
+
+// 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, no-store, no-transform, must-revalidate, 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)
+}