Return ERR_FILE_NOT_FOUND from FtpNetworkTransaction when we can.

net/ftp/ftp_network_transaction.cc

 // Copyright (c) 2008 The Chromium Authors. All rights reserved.  Use of this
 // source code is governed by a BSD-style license that can be found in the
 // LICENSE file.
 
 #include "net/ftp/ftp_network_transaction.h"
 
 #include "base/compiler_specific.h"
 #include "base/string_util.h"
 #include "net/base/connection_type_histograms.h"
 #include "net/base/load_log.h"
@@ skipping 810 matching lines @@
       break;
     case ERROR_CLASS_INFO_NEEDED:
       next_state_ = STATE_CTRL_WRITE_PASV;
       break;
     case ERROR_CLASS_TRANSIENT_ERROR:
       if (response.status_code == 421 || response.status_code == 425 ||
           response.status_code == 426)
         return Stop(ERR_FAILED);
       return ERR_FAILED;  // TODO(ibrar): Retry here.
     case ERROR_CLASS_PERMANENT_ERROR:
-      if (retr_failed_)
+      // Code 550 means "Failed to open file". Other codes are unrelated,
+      // like "Not logged in" etc.
+      if (response.status_code != 550)
         return Stop(ERR_FAILED);
+
+      DCHECK(!retr_failed_);  // Should not get here twice.
       retr_failed_ = true;

[wtc, 2009/09/09 18:41:31]

My question is: are we going to try the CWD command next?
I still don't see the relation between RETR and CWD.

       next_state_ = STATE_CTRL_WRITE_PASV;
       break;
     default:
       NOTREACHED();
       return Stop(ERR_UNEXPECTED);
   }
   return OK;
 }
 
 // MDMT command
@@ skipping 50 matching lines @@
     case ERROR_CLASS_INITIATED:
       return Stop(ERR_INVALID_RESPONSE);
     case ERROR_CLASS_OK:
       next_state_ = STATE_CTRL_WRITE_LIST;
       break;
     case ERROR_CLASS_INFO_NEEDED:
       return Stop(ERR_INVALID_RESPONSE);
     case ERROR_CLASS_TRANSIENT_ERROR:
       return Stop(ERR_FAILED);
     case ERROR_CLASS_PERMANENT_ERROR:
+      if (retr_failed_ && response.status_code == 550) {
+        // Both RETR and CWD failed with codes 550. That means that the path
+        // we're trying to access is not a file, and not a directory. The most
+        // probable interpretation is that it doesn't exist (with FTP we can't
+        // be sure).
+        return Stop(ERR_FILE_NOT_FOUND);
+      }
       return Stop(ERR_FAILED);
     default:
       NOTREACHED();
       return Stop(ERR_UNEXPECTED);
   }
   return OK;
 }
 
 // LIST command
 int FtpNetworkTransaction::DoCtrlWriteLIST() {
@@ skipping 79 matching lines @@
   read_data_buf_->data()[0] = 0;
   return data_socket_->Read(read_data_buf_, read_data_buf_len_,
                             &io_callback_);
 }
 
 int FtpNetworkTransaction::DoDataReadComplete(int result) {
   return result;
 }
 
 }  // namespace net