Add a flag to append a fixed HTTP header to all responses.

main.go

@@ -8,23 +8,51 @@ import (
 	"log"
 	"net/http"
 	"strconv"
+	"strings"
 )
 
 var (
 	// Def of flags
 	portPtr    = flag.Int("p", 8043, "The listening port")
 	path       = flag.String("static", "/srv/http", "The path for the static files")
+	headerFlag = flag.String("appendHeader", "", "HTTP response header, specified as `HeaderName:Value` that should be added to all responses.")
 )
 
+func parseHeaderFlag(headerFlag string) (string, string) {
+	if len(headerFlag) == 0 {
+		return "", ""
+	}
+	pieces := strings.SplitN(headerFlag, ":", 2)
+	if len(pieces) == 1 {
+		return pieces[0], ""
+	}
+	return pieces[0], pieces[1]
+}
+
 func main() {
 
 	flag.Parse()
 
 	port := ":" + strconv.FormatInt(int64(*portPtr), 10)
 
-	fs := http.FileServer(http.Dir(*path))
-	http.Handle("/", fs)
+	handler := http.FileServer(http.Dir(*path))
 
-	log.Println("Listening...")
+	// Extra headers.
+	if len(*headerFlag) > 0 {
+		header, headerValue := parseHeaderFlag(*headerFlag)
+		if len(header) > 0 && len(headerValue) > 0 {
+			fileServer := handler
+			handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set(header, headerValue)
+				fileServer.ServeHTTP(w, r)
+			})
+		} else {
+			log.Println("appendHeader misconfigured; ignoring.")
+		}
+	}
+
+	http.Handle("/", handler)
+
+	log.Printf("Listening at 0.0.0.0%v...", port)
 	log.Fatalln(http.ListenAndServe(port, nil))
 }