cmd/site: opportunistic onion support

cmd/site/altonions.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+)
+
+var altOnionServer = os.Getenv("ALT_ONION_SERVER")
+
+func altOnionHandler(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if altOnionServer != "" {
+			w.Header().Set("Alt-Svc", fmt.Sprintf(`h2="%s:443"; ma=86400; persist=1`, altOnionServer))
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}

cmd/site/main.go

@@ -75,7 +75,7 @@ func main() {
 	}
 
 	ln.Log(context.Background(), ln.F{"action": "http_listening", "port": port})
-	http.ListenAndServe(":"+port, s)
+	http.ListenAndServe(":"+port, altOnionHandler(s))
 }
 
 func requestIDMiddleware(next http.Handler) http.Handler {