[Ssh-sftp-perl-users] Scp

[Thierry C. <thi...@gm...>]

Hello Greg and David,

I see that there is a great work done with Net::SSH::Perl. I am happy 
since I was missing a functionnality, and I think that we can obtain result 
with the additions you have done.

I want to be able to write something like (with an existing ssh object, login 
done)
$ssh->scp_push($localfile,$remotefile);
or
$ssh->scp_get($remotefile,$localfile);

It is possible with the module Net::SSH2 that David have written, and it is 
good enough for me, but ssh-agent si not supported with this module, and it 
is a key point.

I didn't find the RFC where scp is described, so I had to analyze openssh and 
libssh2 in order to understand why I need to do.

I have finally produce a protoype of what I want in Net/SSH/Perl/SSH2.pm

 sub scp_push {
	my $ssh = shift;
	my ($filesrc, $filedest) = @_;
	my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
                      $atime,$mtime,$ctime,$blksize,$blocks)
                          = stat($filesrc);
	open( my $filehandle, "$filesrc" ) or croak("Cannot open file $filesrc $!");
	binmode ($filehandle);
	my @tmp=split("/",$filesrc);
	my $filesrc_invocation=$tmp[$#tmp];


	my $cmd     = "scp -v -t $filedest";
	my $cmgr    = $ssh->channel_mgr;
	my $channel = $ssh->_session_channel;
	$channel->open;
	$channel->register_handler( SSH2_MSG_CHANNEL_OPEN_CONFIRMATION,
		sub {
			my ( $channel, $packet ) = @_;
			$channel->{ssh}->debug("Sending command: $cmd");
			my $r_packet = $channel->request_start( "exec", 0 );
			$r_packet->put_str("$cmd");
			$r_packet->send;

			if (defined $size) {
				
				$channel->send_data("C0644 $size $filesrc_invocation\n");
				use constant CHUNK_SIZE => 8192;
				while (read ($filehandle, my $chunk, CHUNK_SIZE)){
					$channel->send_data($chunk);
					$channel->drain_outgoing;
					$channel->{istate} = CHAN_INPUT_WAIT_DRAIN;
				}
				$channel->send_eof;
				$channel->{istate} = CHAN_INPUT_CLOSED;
			}
		}
	);

..... You know what is next better than me ...
	( $stdout, $stderr, $exit );
}

As you can see, it is bad.  My chunk_size is not large enough to have a good 
rate transfer.  I didn't even know if there is some kind of negociation 
between client and server.  I have write only a small small ;) subset of the 
scp protocol. It is a proof-of-concept prototype.

My questions are:
- I just see in the new 1.31 that there is a Subsystem generic call. Should I 
use it for this piece of code. 
- are you interested by this approach ? Is there something  I don't see that 
is not allowing such functions to work ?
- do you know where I can find a formal description of scp (I find openssh 
code not very documented) ?