I would like to request that a change be added to libcURL so that it will accept a slightly non-compliant FTPD 257 response.

I have written an FTP client to interface with a customized FTP daemon in a storage appliance for the video industry. The vendor of this appliance implemented a non-RFC 959 response 257 to the PWD and MKD commands. The standard specifies the response to PWD and MKD commands be of the following form:

  257<space>"<directory-name>"<space><commentary>

The vendor incorrectly implemented the response in the following form:

  257<space><space><commentary>"<directory-name>"

I could not require that the FTP daemon be fixed and deployed, so I made a simple change to libcURL to accept the non-standard response. Without this change, libcurl can lose track of the HOME directory under the following scenario:

1) Set CURLOPT_FTP_FILEMETHOD to MULTICWD, and upload a temporary file to get libcurl to create the missing elements of a directory path as needed, then DELE the temporary file with a POSTQUOTE command.

2) Set CURLOPT_FTP_FILEMETHOD to NOCWD to support QUOTE commands with pathnames rooted in the user's HOME directory.

I realize that this is an unusual way to use CURLOPT_FTP_FILEMETHOD, but it works with RFC 959 compliant FTP servers. Using MULTICWD allows for efficient directory-path creation, but it is very difficult to use QUOTE commands with MULTICWD since it is difficult to know either the absolute path name or the current directory for a relative path name.

Following is the patch that allows the non-compliant 257 response to be parsed:

--- curl-7.29.0_new/lib/ftp.c 2013-03-25 09:33:57.984270281 -0500
+++ curl-7.29.0/lib/ftp.c 2013-01-17 15:40:43.000000000 -0600
@@ -2873,15 +2873,6 @@
            double-quotes should be escaped by double-quotes (the
            "quote-doubling" convention).
         */
-
- /* scan for the first double-quote for non-standard responses */
- while (ptr < (&(data->state.buffer) + sizeof(data->state.buffer))
- && *ptr != '\0'
- && *ptr != '"'
- ) {
- ptr++;
- }
-
         if('\"' == *ptr) {
           /* it started good */
           ptr++;

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Received on 2013-04-09