Limit the use of -e to a single keyword (#106)

* Limit the use of extension to a single wordlist

* Update README

README.md

@@ -193,6 +193,7 @@ The only dependency of ffuf is Go 1.11. No dependencies outside of Go standard l
 - master
   - New
   - Changed
+    - Limit the use of `-e` (extensions) to a single keyword: FUZZ
 
 - v0.12
   - New

main.go

@@ -60,7 +60,7 @@ func main() {
 	conf := ffuf.NewConfig(ctx)
 	opts := cliOptions{}
 	var ignored bool
-	flag.StringVar(&opts.extensions, "e", "", "Comma separated list of extensions to apply. Each extension provided will extend the wordlist entry once.")
+	flag.StringVar(&opts.extensions, "e", "", "Comma separated list of extensions to apply. Each extension provided will extend the wordlist entry once. Only extends a wordlist with (default) FUZZ keyword.")
 	flag.BoolVar(&conf.DirSearchCompat, "D", false, "DirSearch style wordlist compatibility mode. Used in conjunction with -e flag. Replaces %EXT% in wordlist entry with each of the extensions provided by -e.")
 	flag.Var(&opts.headers, "H", "Header `\"Name: Value\"`, separated by colon. Multiple -H flags are accepted.")
 	flag.StringVar(&conf.Url, "u", "", "Target URL")

pkg/input/wordlist.go

@@ -121,7 +121,7 @@ func (w *WordlistInput) readFile(path string) error {
 			}
 		} else {
 			data = append(data, []byte(reader.Text()))
-			if len(w.config.Extensions) > 0 {
+			if w.keyword == "FUZZ" && len(w.config.Extensions) > 0 {
 				for _, ext := range w.config.Extensions {
 					data = append(data, []byte(reader.Text()+ext))
 				}