[vlc-devel] [PATCH] smb: try libdsm first

[Alexandre Janniaux]

Would it have some meaning to try smb2 but failing if authentication is
required, then try libdsm, and if it fails try smb2 again but handle
authentication? Maybe a smart thing can be done with keystore to fix this in the
first case.

It could be achieved by a dual capability in the smb2 module.

Regards,
--
Alexandre Janniaux
Videolabs

On Tue, Oct 15, 2019 at 03:41:17PM +0200, Thomas Guillem wrote:
> Some samba servers (on Windows 7) implement both SMB2 and SMB1. The problem is
> that the SMB2 part is not configured like the SMB1 one. Only SMB1 seems to
> reflect the user configuration (using Windows Settings, not anything
> complicated like via powershell/regedit).
>
> If we try to connect to such server via libsmb2, the server will return a
> SMB2_STATUS_ACCESS_DENIED (0xC0000022) status. Our libsmb2 module will then ask
> the user for credentials via a dialog. The problem is that no credentials will
> ever work since only the SMB1 part is configured.
>
> I tried to differentiate (via wireshark) the negotiation between such server
> and an other working SMB2 server but could not find anything that could tell us
> that this ACCESS_DENIED status should be ignored on this specific server (in
> order to fallback to libdsm).
>
> The only possible fix is to try libdsm first. VLC will then favor the SMB1
> protocol over SMB 2&3.
>
> NB1: libsmb2 is backported to VLC 3.0 for iOS and Android ports. These ports
> are beta-testing SMB 2&3 support on mobile.
>
> NB2: We get a lot of angry mail/reviews about SMB1 support broken, I don't
> think we can drop SMB1 (even if I would love to).
>
> NB3: We can't drop libsmb2 either for the same reason (we got a *lot* of
> requests to support it).
> ---
>  modules/access/dsm/access.c | 17 ++++++++++-------
>  modules/access/smb2.c       | 14 +++++++-------
>  2 files changed, 17 insertions(+), 14 deletions(-)
>
> diff --git a/modules/access/dsm/access.c b/modules/access/dsm/access.c
> index 776925c9eeb..186a567a72c 100644
> --- a/modules/access/dsm/access.c
> +++ b/modules/access/dsm/access.c
> @@ -69,7 +69,7 @@ vlc_module_begin ()
>      set_shortname( "dsm" )
>      set_description( N_("libdsm SMB input") )
>      set_help(BDSM_HELP)
> -    set_capability( "access", 20 )
> +    set_capability( "access", 22 )
>      set_category( CAT_INPUT )
>      set_subcategory( SUBCAT_INPUT_ACCESS )
>      add_string( "smb-user", NULL, SMB_USER_TEXT, SMB_USER_LONGTEXT, false )
> @@ -343,12 +343,6 @@ static int login( stream_t *p_access )
>
>      if( connect_err == EACCES )
>      {
> -        if (var_Type(p_access, "smb-dialog-failed") != 0)
> -        {
> -            /* A higher priority smb module (likely smb2) already requested
> -             * credentials to the users. It is useless to request it again. */
> -            goto error;
> -        }
>          while( connect_err == EACCES
>              && vlc_credential_get( &credential, p_access, "smb-user", "smb-pwd",
>                                     SMB_LOGIN_DIALOG_TITLE,
> @@ -365,6 +359,15 @@ static int login( stream_t *p_access )
>          if( connect_err != 0 )
>          {
>              msg_Err( p_access, "Unable to login" );
> +
> +            if (credential.i_get_order == GET_FROM_DIALOG)
> +            {
> +                /* Tell other smb modules (likely smb2) that we already
> +                 * requested credential to the users and that it it useless to
> +                 * try again.  This avoid to show 2 login dialogs for the same
> +                 * access. */
> +                var_Create(p_access, "smb-dialog-failed", VLC_VAR_VOID);
> +            }
>              goto error;
>          }
>      }
> diff --git a/modules/access/smb2.c b/modules/access/smb2.c
> index 923e6d57e04..7f9b614d006 100644
> --- a/modules/access/smb2.c
> +++ b/modules/access/smb2.c
> @@ -664,6 +664,13 @@ Open(vlc_object_t *p_obj)
>                         NULL);
>      ret = vlc_smb2_open_share(access, smb2_url, &credential);
>
> +    if (ret == -1 && var_Type(access, "smb-dialog-failed"))
> +    {
> +        /* A higher priority smb module (likely dsm) already requested
> +         * credentials to the users. It is useless to request it again. */
> +        goto error;
> +    }
> +
>      while (ret == -1
>          && (!sys->error_status || VLC_SMB2_STATUS_DENIED(sys->error_status))
>          && vlc_credential_get(&credential, access, "smb-user", "smb-pwd",
> @@ -683,13 +690,6 @@ Open(vlc_object_t *p_obj)
>          if (error && *error)
>              vlc_dialog_display_error(access,
>                                       _("SMB2 operation failed"), "%s", error);
> -        if (credential.i_get_order == GET_FROM_DIALOG)
> -        {
> -            /* Tell other smb modules (likely dsm) that we already requested
> -             * credential to the users and that it it useless to try again.
> -             * This avoid to show 2 login dialogs for the same access. */
> -            var_Create(access, "smb-dialog-failed", VLC_VAR_VOID);
> -        }
>          goto error;
>      }
>
> --
> 2.20.1
>
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