bug#18199: 24.4.50; tramp uses wrong arguments to nc

bug#18199: 24.4.50; tramp uses wrong arguments to nc

[Jason Rumney]

When connecting to a Busybox/Linux based router with tramp's new nc method,
the file transfer fails.  Below is the relevant debug log:

---------------------------------------------------------------------
///3359aa65e9a4645eb0b84d831a25d5c2#$
23:26:29.200991 tramp-send-command (6) # nc -l -p 51257 </etc/TZ &
23:26:29.250828 tramp-wait-for-regexp (6) # 

///3359aa65e9a4645eb0b84d831a25d5c2#$
23:26:29.251550 tramp-send-command (6) # netstat -l | grep -q :51257
23:26:29.308484 tramp-wait-for-regexp (6) # 
BusyBox v1.6.1 (2011-05-25 14:47:48 CST) multi-call binary

Usage: 
nc [IPADDR PORTNUM]

Open a pipe to IP:port

[1] + Done(1)                    nc -l -p 51257 0</etc/TZ
---------------------------------------------------------------------

Although the usage message from BusyBox seems to suggest it does not
accept any options, it does in fact accept the -l option.  It is the -p
option that is a problem here.  The manpage for the full BSD nc command
says the following:

     -l      Used to specify that nc should listen for an incoming connection
             rather than initiate a connection to a remote host.  It is an
             error to use this option in conjunction with the -p, -s, or -z
             options.  Additionally, any timeouts specified with the -w option
             are ignored.

The actual command required is

   nc -l 51257 </etc/TZ &





In GNU Emacs 24.4.50.3 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
 of 2014-08-05 on wanchan
Repository revision: 117648 rudalics@gmx.at-20140805082528-lggey1cjbd1jl06e
Windowing system distributor `The X.Org Foundation', version 11.0.11501000
System Description:	Ubuntu 14.04 LTS

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GCONF GSETTINGS NOTIFY
GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB

Important settings:
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  value of $LC_NUMERIC: en_NZ.UTF-8
  value of $LC_TIME: en_NZ.UTF-8
  value of $LANG: en_NZ.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Outline

Minor modes in effect:
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Recent input:
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> <down-mouse-5> 
<mouse-5> <down-mouse-1> <mouse-1> <down-mouse-5> <mouse-5> 
<double-down-mouse-5> <double-mouse-5> <down-mouse-5> 
<mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-4> <mouse-4> <mouse-movement> 
<mouse-movement> <drag-mouse-1> <down-mouse-1> <mouse-movement> 
<mouse-1> <mouse-movement> <mouse-movement> <mouse-movement> 
<drag-mouse-1> <down-mouse-5> <mouse-5> <escape> w 
<down-mouse-4> <mouse-4> <help-echo> <help-echo> <down-mouse-4> 
<mouse-4> <down-mouse-4> <mouse-4> <down-mouse-1> <mouse-1> 
<down> <left> <up> <up> <up> <down> <down> <down> <up> 
<up> <up> <up> <up> <up> <down-mouse-4> <mouse-4> <double-down-mouse-4> 
<double-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <down-mouse-1> <mouse-1> C-s n c SPC 
<down> <mouse-movement> <mouse-movement> <drag-mouse-1> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<drag-mouse-1> <mouse-movement> <mouse-movement> <mouse-movement> 
<drag-mouse-1> <down-mouse-1> <mouse-1> <down-mouse-5> 
<mouse-5> <down-mouse-1> <mouse-movement> <drag-mouse-1> 
<down-mouse-5> <mouse-5> <down-mouse-5> <mouse-5> <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <down-mouse-5> 
<mouse-5> <down-mouse-4> <mouse-4> <double-down-mouse-4> 
<double-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <down-mouse-4> 
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<down-mouse-4> <mouse-4> <double-down-mouse-4> <double-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <down-mouse-4> 
<mouse-4> <double-down-mouse-4> <double-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <triple-down-mouse-4> <triple-mouse-4> 
<triple-down-mouse-4> <triple-mouse-4> <triple-down-mouse-4> 
<triple-mouse-4> <down-mouse-5> <mouse-5> <double-down-mouse-5> 
<double-mouse-5> <down-mouse-5> <mouse-5> <down-mouse-5> 
<mouse-5> <double-down-mouse-5> <double-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <triple-down-mouse-5> <triple-mouse-5> 
<triple-down-mouse-5> <triple-mouse-5> <triple-down-mouse-5> 
<triple-mouse-5> <down-mouse-1> <mouse-1> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<drag-mouse-1> <mouse-movement> <mouse-movement> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<drag-mouse-1> <escape> w <mouse-movement> <mouse-movement> 
<mouse-movement> <mouse-movement> <mouse-movement> 
<mouse-movement> <drag-mouse-1> <escape> w <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <menu-bar> <help-menu> 
<send-emacs-bug-report>

Recent messages:
Tramp: Inserting `/nc:mt7109@10.1.1.254:/etc/TZ'...failed
File exists, but cannot be read

Tramp: Checking `vc-registered' for /nc:mt7109@10.1.1.254:/etc/TZ...done
File exists, but cannot be read
Mark set [10 times]
<left-fringe> <mouse-5> is undefined
<left-fringe> <double-mouse-5> is undefined
Mark set [4 times]
Mark saved where search started

Load-path shadows:
None found.

Features:
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bug#18199: 24.4.50; tramp uses wrong arguments to nc

[Michael Albinus]

Jason Rumney <jasonr@gnu.org> writes:

Hi Jason,

> When connecting to a Busybox/Linux based router with tramp's new nc method,
> the file transfer fails.  Below is the relevant debug log:
>
> ---------------------------------------------------------------------
> ///3359aa65e9a4645eb0b84d831a25d5c2#$
> 23:26:29.200991 tramp-send-command (6) # nc -l -p 51257 </etc/TZ &
> 23:26:29.250828 tramp-wait-for-regexp (6) # 
>
> ///3359aa65e9a4645eb0b84d831a25d5c2#$
> 23:26:29.251550 tramp-send-command (6) # netstat -l | grep -q :51257
> 23:26:29.308484 tramp-wait-for-regexp (6) # 
> BusyBox v1.6.1 (2011-05-25 14:47:48 CST) multi-call binary
>
> Usage: 
> nc [IPADDR PORTNUM]
>
> Open a pipe to IP:port

[...]

> The actual command required is
>
>    nc -l 51257 </etc/TZ &

Well, as you might guess I have tested this with my own equipment. My
silly router runs a more recent version of busybox, which requires the
"-p" prefix for nc's port specification:

--8<---------------cut here---------------start------------->8---
# nc -l 51257
nc: bad address '51257'
# nc -h
nc: invalid option -- h
BusyBox v1.19.3 (2012-08-08 12:53:46 CEST) multi-call binary.

Usage: nc [-iN] [-wN] [-l] [-p PORT] [-f FILE|IPADDR PORT] [-e PROG]

Open a pipe to IP:PORT or FILE

        -e PROG Run PROG after connect
        -l      Listen mode, for inbound connects
                (use -l twice with -e for persistent server)
        -p PORT Local port
        -w SEC  Timeout for connect
        -i SEC  Delay interval for lines sent
        -f FILE Use file (ala /dev/ttyS0) instead of network
--8<---------------cut here---------------end--------------->8---

I don't see how to unify both syntax variants. Therfore, I will add a
check for nc prior the first call, in order to determine what to
use. Alternatively, it could be made configurable; haven't decided yet.

This might take some days. For further testing (which would much be
appreciated!), you could use the following patch:

--8<---------------cut here---------------start------------->8---
*** /home/albinus/src/emacs/lisp/net/tramp-sh.el.~117648~	2014-08-06 09:23:05.687261671 +0200
--- /home/albinus/src/emacs/lisp/net/tramp-sh.el	2014-08-06 09:22:01.750100553 +0200
***************
*** 218,225 ****
      ;; We use "-v" for better error tracking.
      (tramp-copy-args            (("-w" "1") ("-v") ("%h") ("%r")))
      (tramp-remote-copy-program  "nc")
!     ;; We use "-p" as required for busyboxes.
!     (tramp-remote-copy-args     (("-l") ("-p" "%r")))
      (tramp-default-port         23)))
  ;;;###tramp-autoload
  (add-to-list 'tramp-methods
--- 218,224 ----
      ;; We use "-v" for better error tracking.
      (tramp-copy-args            (("-w" "1") ("-v") ("%h") ("%r")))
      (tramp-remote-copy-program  "nc")
!     (tramp-remote-copy-args     (("-l") ("%r")))
      (tramp-default-port         23)))
  ;;;###tramp-autoload
  (add-to-list 'tramp-methods
--8<---------------cut here---------------end--------------->8---

Best regards, Michael.

bug#18199: 24.4.50; tramp uses wrong arguments to nc

[Andreas Schwab]

Michael Albinus <michael.albinus@gmx.de> writes:

> Well, as you might guess I have tested this with my own equipment. My
> silly router runs a more recent version of busybox, which requires the
> "-p" prefix for nc's port specification:
>
> # nc -l 51257
> nc: bad address '51257'
> # nc -h
> nc: invalid option -- h
> BusyBox v1.19.3 (2012-08-08 12:53:46 CEST) multi-call binary.
>
> Usage: nc [-iN] [-wN] [-l] [-p PORT] [-f FILE|IPADDR PORT] [-e PROG]

It's more likely a BusyBox configure option, since the version I have
(v1.19.4 from openWRT) doesn't even accept -l.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

bug#18199: 24.4.50; tramp uses wrong arguments to nc

[Michael Albinus]

Andreas Schwab <schwab@suse.de> writes:

> It's more likely a BusyBox configure option, since the version I have
> (v1.19.4 from openWRT) doesn't even accept -l.

Indeed, there is a busybox build time option (CONFIG_NC_SERVER). But
this is not related to the used command line syntax.

Agreed, Tramp shall check whether the nc listening feature is enabled;
it shall raise an error in case it isn't. Noted.

> Andreas.

Best regards, Michael.

bug#18199: 24.4.50; tramp uses wrong arguments to nc

[Jason Rumney]

tag 18199 wontfix
close 18199
thanks

Andreas Schwab <schwab@suse.de> writes:

> Michael Albinus <michael.albinus@gmx.de> writes:
>
>> Well, as you might guess I have tested this with my own equipment. My
>> silly router runs a more recent version of busybox, which requires the
>> "-p" prefix for nc's port specification:
>
> It's more likely a BusyBox configure option, since the version I have
> (v1.19.4 from openWRT) doesn't even accept -l.

Now that I've modified my local tramp to remove the -p, I find that
though nc -l 51257 does not give any errors, it isn't actually listening
on the port either.  I'm not sure what it is doing.

bug#18199: 24.4.50; tramp uses wrong arguments to nc

[Michael Albinus]

Jason Rumney <jasonr@gnu.org> writes:

> Now that I've modified my local tramp to remove the -p, I find that
> though nc -l 51257 does not give any errors, it isn't actually listening
> on the port either.  I'm not sure what it is doing.

As said in my other message to Andreas, busybox might not be compiled
with the nc listening feature.

Anyway, I've committed a patch which allows you to overwrite the "nc -l
..." arguments. Tramp's manual says

--8<---------------cut here---------------start------------->8---
     The ‘nc’ command will be used with the ‘nc’ method.  On the remote
     host, a listener will be installed.  Unfortunately, the command
     line syntax for this has been changed with the different ‘busybox’
     versions.  TRAMP uses the following syntax (see ‘tramp-methods’):

          # nc -l -p 42

     If your remote ‘nc’ refuses to accept the ‘-p’ parameter, you could
     overwrite the syntax with the following form:

          (add-to-list
           'tramp-connection-properties
           `(,(regexp-quote "192.168.0.1") "remote-copy-args" (("-l") ("%r"))))

     with ‘192.168.0.1’ being the IP address of your remote host (*note
     Predefined connection information::).
--8<---------------cut here---------------end--------------->8---

Best regards, Michael.