Disallow op with no fingerprint.

client.go

@@ -347,8 +347,12 @@ func (c *Client) handleShell(channel ssh.Channel) {
 						c.SysMsg("No such name: %s", parts[1])
 					} else {
 						fingerprint := client.Fingerprint()
-						client.SysMsg("Made op by %s.", c.ColoredName())
-						c.Server.Op(fingerprint)
+						if fingerprint == "" {
+							c.SysMsg("Cannot op user without fingerprint.")
+						} else {
+							client.SysMsg("Made op by %s.", c.ColoredName())
+							c.Server.Op(fingerprint)
+						}
 					}
 				}
 			case "/kick":

server.go

@@ -363,6 +363,10 @@ func (s *Server) Uptime() string {
 
 // IsOp checks if the given client is Op
 func (s *Server) IsOp(client *Client) bool {
+	fingerprint := client.Fingerprint()
+	if fingerprint == "" {
+		return false
+	}
 	_, r := s.admins[client.Fingerprint()]
 	return r
 }