Re: Net::SSH::Perl doesn't like long commands

This looks like a bug on Net::SSH::Perl.

I can reproduce the problem myself. In my environment, Net::SSH::Perl hangs at some point between 8000 and 10000 characters.

Net::OpenSSH can handle the same commands without any issue (that's why I think the problem lies on Net::SSH::Perl):

#!/usr/bin/perl
use strict;
use Net::OpenSSH;
use Net::SSH::Perl;

my $host = $ARGV[0] // "localhost";

for my $len (10, 100, 1000, 2000, 4000, 6000, 8000, 10000, 20000, 5000
+0) {

    my $cmd = "echo ";
    $cmd .= "." x $len;

    warn "trying with Net::OpenSSH, len=$len...\n";
    my $ssh1 = Net::OpenSSH->new($host);

    my ($stdout1, $stderr1) = $ssh1->capture($cmd) or die "Failed!\n";
    warn "Failed $?!\n" if $?;

    warn "trying with Net::SSH::Perl, len=$len...\n";
    my $ssh2 = Net::SSH::Perl->new( $host,
                                    # debug => 1,
                                    options => [ "BatchMode yes",
                                                 "PasswordAuthenticati
+on no",
                                                 "ConnectTimeout 15" ]
+ );
    $ssh2->login("root") or die "Failed to login: $!\n";
    warn "logged\n";
    my ($stdout2, $stderr2, $exit) = $ssh2->cmd($cmd);
    warn "Failed $exit!\n" if $exit;

}
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Re^2: Net::SSH::Perl doesn't like long commands by BrowserUk (Patriarch) on Jun 10, 2013 at 12:23 UTC
hangs at some point between 8000 and 10000 characters. What's the betting that it is somewhere around 8192, the size of PerlIO IO buffers since 5.1(2\|4\|?). Maybe someone how has reproduced it could try disabling the buffering and see if that changes anything. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^3: Net::SSH::Perl doesn't like long commands by vsespb (Chaplain) on Jun 10, 2013 at 13:33 UTC
I see syswrite calls in this code http://cpansearch.perl.org/src/SCHWIGON/Net-SSH-Perl-1.35/lib/Net/SSH/Perl/Packet.pm Looks like it's not protected from EAGAIN and from case when syswrite didn't write all data. sysread calls are protected.	[reply]
Re^3: Net::SSH::Perl doesn't like long commands by salva (Canon) on Jun 10, 2013 at 13:38 UTC
It is very unlikely that buffering may be the root of the problem because of the way the SSH protocol is internally structured in several layers. A buffering issue would have manifested itself as a wider set of problems.	[reply]
Re^3: Net::SSH::Perl doesn't like long commands by pattyj (Novice) on Jun 10, 2013 at 13:07 UTC
Setting $\|++ doesn't help unfortunately (and the value on my boxes are different, see above... :/ ).	[reply]
Re^4: Net::SSH::Perl doesn't like long commands by BrowserUk (Patriarch) on Jun 10, 2013 at 13:12 UTC
Setting $\|++ doesn't help Worth a shot as it doesn't involve a lot of effort. (You do know that for $\|++ to affect the socket in question, it needs to be selected first?) With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]


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