clarifications for SFTP extensions draft

[denis bider <ietf-ssh%denisbider.com@localhost>]

Hello all,

I feel that the SFTP extensions draft is in places underspecified.

For example, it is not explicitly stated what kind of an extension "vendor-id" is. Is this extension included in the server's VERSION packet? The specification doesn't say so; one might even be lead to think that it's a response to an SSH_FXP_EXTEND packet that must be sent by the client.

How does the server advertise that it supports the "check file" extension? There are two possible request names: "check-file-name" and "check-file-handle". In the "supported2" VERSION extension, should the server advertise "check-file", "check-file-name", "check-file-handle", or a combination thereof? Does it make sense for the server to implement only check-file-name, but not also check-file-handle? (My preference - the server should advertise "check-file" and support both.)

Why does the "check file" reply include the string "check-file"? The format of SSH_FXP_EXTENDED_REPLY does not require any such string; the response should be traced back to the original request by ID. Also, no such extra string is specified for "space-available". However, there is such an extra string in the reply for "home-directory". Unless someone already has a fielded implementation, I suggest that we get rid of these while there is time.

Best regards,

denis