9.3  Querying User Home Directory

   Many users are used to being able to type '~' as an alias for their
   home directory, or ~username as an alias for another user's home
   directory.  To support this feature, a server MAY support following
   extension.

       byte   SSH_FXP_EXTENDED
       uint32 request-id
       string "home-directory"
       string username     [UTF-8]

   username
      Username whose home directory path is being requested.  An empty
      string implies the current user.

   The reply to the request is either a SSH_FXP_STATUS packet or the
   following extended reply:

       byte   SSH_FXP_EXTENDED_REPLY
       uint32 request-id
       string "home-directory"
       string absolute-pathname

   absolute-pathname
      Absolute pathname of the specified user's home directory, suitable
      for use in operations such as REALPATH or OPENDIR.