Added ListSubscriber, Unpublish and Retrieve commands

shared/users.go

@@ -61,6 +61,17 @@ func (u users) Set(username string, key, data string) {
 	go uf.write()
 }
 
+// Get all known usernames
+func (u users) GetUsernames() []string {
+	u.mutex.Lock()
+	defer u.mutex.Unlock()
+	var usernames []string
+	for username, _ := range u.data {
+		usernames = append(usernames, username)
+	}
+	return usernames
+}
+
 func (u usersFile) read() {
 	u.mutex.Lock()
 	defer u.mutex.Unlock()