[wp-trac] [WordPress Trac] #51170: FTP automatic updates are not RFC 959 compliant for NLST command

[WordPress Trac]

#51170: FTP automatic updates are not RFC 959 compliant for NLST command
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 Reporter:  giox069           |       Owner:  afragen
     Type:  defect (bug)      |      Status:  assigned
 Priority:  normal            |   Milestone:  6.0
Component:  Filesystem API    |     Version:  3.7
 Severity:  normal            |  Resolution:
 Keywords:  has-patch commit  |     Focuses:
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Comment (by pbiron):

 I just found a [https://stackoverflow.com/a/16224707 StackOverflow reply]
 where someone who claims to be the author of particular FTP server
 software mentions that his FTP server specifically returns an error if the
 `SIZE` command is issued when `TYPE` is not `BINARY` :-(

 He quotes from the section about the `SIZE` command in the
 [https://datatracker.ietf.org/doc/html/rfc3659#section-4.2 RFC]:

   4.2.  Error Responses
   Where the command is correctly parsed but the size is not available,
   perhaps because the pathname identifies no existing entity or because
   the entity named cannot be transferred in the current MODE and TYPE
   (or at all), then a 550 reply should be sent.
   ....
   The presence of the 550 error response to a SIZE
   command MUST NOT be taken by the client as an indication that the
   file cannot be transferred in the current MODE and TYPE.  A server
   may generate this error for other reasons -- for instance if the
   processing overhead is considered too great.

 note: the server responding with anything other than a `213` response code
 will result in `ftp_size()` returning `-1`...see the
 [https://github.com/php/php-
 src/blob/efbb2198d4e5a01167d1a8c2937b848f75ac4d19/ext/ftp/ftp.c#L1120 PHP
 source for ftp_size()].

 So, maybe using `ftp_size()` to check for file existence is **not** a
 viable approach?  Of course, I'm not saying that we shouldn't use
 it...just try to make sure we don't introduce other problems with this
 "fix".

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/51170#comment:20>
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