Disable sign-up by default, enable by new --signup flag.

README.md

@@ -64,17 +64,22 @@ This is [a common privilege problem](http://stackoverflow.com/q/413807) and
 
     sudo setcap 'cap_net_bind_service=+ep' $GOPATH/bin/htwtxt
 
-### Changing HTML templates
+### Opening up sign-up
 
-By default, HTML templates are read out of `$GOPATH/src/htwtxt/templates/`. An
-alternate directory can be given with the flag `--templates` (it should contain
-template files of the same names as the default ones, however).
+By default, sign up / account creation is not open to the public. The `--signup`
+flag must be set explicitely to change that.
 
 ### Setting site owner contact info
 
 The server serves a `/info` page (from the `info.html` template) that may
 include the site owner's contact info, as given with the `--info` flag.
 
+### Changing HTML templates
+
+By default, HTML templates are read out of `$GOPATH/src/htwtxt/templates/`. An
+alternate directory can be given with the flag `--templates` (it should contain
+template files of the same names as the default ones, however).
+
 ## Copyright, license
 
 htwtxt (c) 2016 Christian Heller a.k.a. plomlompom

main.go

@@ -25,6 +25,7 @@ var feedsPath string
 var templPath string
 var templ *template.Template
 var contactString string
+var signupOpen bool
 
 func createFileIfNotExists(path string) {
 	if _, err := os.Stat(path); err != nil {
@@ -149,10 +150,19 @@ func infoHandler(w http.ResponseWriter, r *http.Request) {
 }
 
 func signUpFormHandler(w http.ResponseWriter, r *http.Request) {
+	if !signupOpen {
+		execTemplate(w, "nosignup.html", "")
+		return
+	}
 	execTemplate(w, "signupform.html", "")
 }
 
 func signUpHandler(w http.ResponseWriter, r *http.Request) {
+	if !signupOpen {
+		execTemplate(w, "error.html",
+			"Account creation currently not allowed.")
+		return
+	}
 	newLine, err := accountLine(w, r, true)
 	if err != nil {
 		return
@@ -268,6 +278,8 @@ func main() {
 	flag.StringVar(&contactString, "contact",
 		"[operator passed no contact info to server]",
 		"operator contact info to display on info page")
+	flag.BoolVar(&signupOpen, "signup", false,
+		"enable on-site account creation")
 	flag.Parse()
 	log.Println("Using as templates dir:", templPath)
 	log.Println("Using as data dir:", dataDir)

templates/nosignup.html

@@ -0,0 +1,6 @@
+{{ template "header" }}
+<section>
+	<h2>Account creation closed</h2>
+    <p>The site operator has not decided to open up account creation on this site for the public.</p>
+</section>
+{{ template "footer" }}