proc_open interaction - ssh

Here's what I'm trying to achieve: open a shell (korn or bash, doesn't matter), from that shell, I want to open a ssh connection (ssh user#host). At some point it is likely to happen I will be prompted for either a password or I might be asked whether or not I'm sure I want to connect (offending keys).
Before anyone asks: yes, I am aware there is a plugin for ssh2 exec calls, but the servers I'm working on don't support it, and are unlikely to do so.
Here's what I've tried so far:
$desc = array(array('pipe','r'),array('pipe','w'));//used in all example code
$p = proc_open('ssh user#host',$desc,$pipes);
if(!is_resource($p)){ die('#!#$%');}//will omit this line from now on
sleep(1);//omitting this,too but it's there every time I need it
Then I tried to read console output (stream_get_contents($pipes[1])) to see what I have to pass next (either password, yes or return 'connection failed: '.stream_get_contents($pipes[1]) and proc_close $p.
This gave me the following error:
Pseudo-terminal will not be allocated because stdin is not a terminal.
So, I though ssh was called in the php:// io-stream context, seems a plausible explanation of the above error.
Next: I though about my first SO question and decided it might be a good idea to open a bash/ksh shell first:
$p = proc_open('bash',$desc,$pipes);
And take it from there, but I got the exact same error message, only this time, the script stopped running but ssh did run. So I got hopeful, then felt stupid and, eventually, desperate:
$p=proc_open('bash && ssh user#host',$desc,$pipes);
After a few seconds wait, I got the following error:
PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 133693440 bytes)
The Call Stack keeps bringing up the stream_get_contents line, even in my last desperate attempt:
#!/path/to/bin/php -n
<?php
$p = proc_open('bash && ssh user#host',array(array('pipe','r'),array('pipe','w')),$ps);
if (!is_resource($p))
{
die('FFS');
}
usleep(10);
fwrite($ps[0],'yes'."\n");
fflush($ps[0]);
usleep(20);
fwrite($ps[0],'password'."\n");
fflush($ps[0]);
usleep(20);
fwrite($ps[0],'whoami'."\n");
fflush($ps[0]);
usleep(2);
$msg = stream_get_contents($ps[1]);
fwrite($ps[0],'exit'."\n");
fclose($ps[0]);
fclose($ps[1]);
proc_close($p);
?>
I know, its a mess, a lot of fflush and redundancy, but the point is: I know this connection will first prompt me for offending keys, and then ask a password. My guess is the stream in $pipes[1] holds the ssh connection, hence it's content is huge. what I need then, is a pipe inside a pipe... is this even possible? I must be missing something, what good is a pipe if this isn't possible...
My guess is the proc_open command is wrong to begin with, (error: Broken pipe). But I really can't see any other way around the first error... any thoughts? Or follow up questions if the above rant isn't at all clear (which it probably isn't).

Before anyone asks: yes, I am aware there is a plugin for ssh2 exec
calls, but the servers I'm working on don't support it, and are
unlikely to do so.
There are actually two. The PECL module, which is a PITA that most servers don't have installed anyway and phpseclib, a pure PHP SSH2 implementation. An example of its use:
<?php
include('Net/SSH2.php');
$ssh = new Net_SSH2('www.domain.tld');
if (!$ssh->login('username', 'password')) {
exit('Login Failed');
}
echo $ssh->exec('pwd');
echo $ssh->exec('ls -la');
?>

Related

Asynchronous reading of an stdout

I've wrote this simple script, it generates one output line per second (generator.sh):
for i in {0..5}; do echo $i; sleep 1; done
The raku program will launch this script and will print the lines as soon as they appear:
my $proc = Proc::Async.new("sh", "generator.sh");
$proc.stdout.tap({ .print });
my $promise = $proc.start;
await $promise;
All works as expected: every second we see a new line. But let's rewrite generator in raku (generator.raku):
for 0..5 { .say; sleep 1 }
and change the first line of the program to this:
my $proc = Proc::Async.new("raku", "generator.raku");
Now something wrong: first we see first line of output ("0"), then a long pause, and finally we see all the remaining lines of the output.
I tried to grab output of the generators via script command:
script -c 'sh generator.sh' script-sh
script -c 'raku generator.raku' script-raku
And to analyze them in a hexadecimal editor, and it looks like they are the same: after each digit, bytes 0d and 0a follow.
Why is such a difference in working with seemingly identical generators? I need to understand this because I am going to launch an external program and process its output online.
Why is such a difference in working with seemingly identical generators?
First, with regard to the title, the issue is not about the reading side, but rather the writing side.
Raku's I/O implementation looks at whether STDOUT is attached to a TTY. If it is a TTY, any output is immediately written to the output handle. However, if it's not a TTY, then it will apply buffering, which results in a significant performance improvement but at the cost of the output being chunked by the buffer size.
If you change generator.raku to disable output buffering:
$*OUT.out-buffer = False; for 0..5 { .say; sleep 1 }
Then the output will be seen immediately.
I need to understand this because I am going to launch an external program and process its output online.
It'll only be an issue if the external program you launch also has such a buffering policy.
In addition to answer of #Jonathan Worthington. Although buffering is an issue of writing side, it is possible to cope with this on the reading side. stdbuf, unbuffer, script can be used on linux (see this discussion). On windows only winpty helps me, which I found here.
So, if there are winpty.exe, winpty-agent.exe, winpty.dll, msys-2.0.dll files in working directory, this code can be used to run program without buffering:
my $proc = Proc::Async.new(<winpty.exe -Xallow-non-tty -Xplain raku generator.raku>);

Is it possible to enable exit on error behavior in an interactive Tcl shell?

I need to automate a huge interactive Tcl program using Tcl expect.
As I realized, this territory is really dangerous, as I need to extend the already existing mass of code, but I can't rely on errors actually causing the program to fail with a positive exit code as I could in a regular script.
This means I have to think about every possible thing that could go wrong and "expect" it.
What I currently do is use a "die" procedure instead of raising an error in my own code, that automatically exits. But this kind of error condition can not be catched, and makes it hard to detect errors especially in code not written by me, since ultimately, most library routines will be error-based.
Since I have access to the program's Tcl shell, is it possible to enable fail-on-error?
EDIT:
I am using Tcl 8.3, which is a severe limitation in terms of available tools.
Examples of errors I'd like to automatically exit on:
% puts $a(2)
can't read "a(2)": no such element in array
while evaluating {puts $a(2)}
%
% blublabla
invalid command name "blublabla"
while evaluating blublabla
%
As well as any other error that makes a normal script terminate.
These can bubble up from 10 levels deep within procedure calls.
I also tried redefining the global error command, but not all errors that can occur in Tcl use it. For instance, the above "command not found" error did not go through my custom error procedure.
Since I have access to the program's Tcl shell, is it possible to
enable fail-on-error?
Let me try to summarize in my words: You want to exit from an interactive Tcl shell upon error, rather than having the prompt offered again?
Update
I am using Tcl 8.3, which is a severe limitation in terms of available
tools [...] only source patches to the C code.
As you seem to be deep down in that rabbit hole, why not add another source patch?
--- tclMain.c 2002-03-26 03:26:58.000000000 +0100
+++ tclMain.c.mrcalvin 2019-10-23 22:49:14.000000000 +0200
## -328,6 +328,7 ##
Tcl_WriteObj(errChannel, Tcl_GetObjResult(interp));
Tcl_WriteChars(errChannel, "\n", 1);
}
+ Tcl_Exit(1);
} else if (tsdPtr->tty) {
resultPtr = Tcl_GetObjResult(interp);
Tcl_GetStringFromObj(resultPtr, &length);
This is untested, the Tcl 8.3.5 sources don't compile for me. But this section of Tcl's internal are comparable to current sources, tested using my Tcl 8.6 source installation.
For the records
With a stock shell (tclsh), this is a little fiddly, I am afraid. The following might work for you (though, I can imagine cases where this might fail you). The idea is
to intercept writes to stderr (this is to where an interactive shell redirects error messages, before returning to the prompt).
to discriminate between arbitrary writes to stderr and error cases, one can use the global variable ::errorInfo as a sentinel.
Step 1: Define a channel interceptor
oo::class create Bouncer {
method initialize {handle mode} {
if {$mode ne "write"} {error "can't handle reading"}
return {finalize initialize write}
}
method finalize {handle} {
# NOOP
}
method write {handle bytes} {
if {[info exists ::errorInfo]} {
# This is an actual error;
# 1) Print the message (as usual), but to stdout
fconfigure stdout -translation binary
puts stdout $bytes
# 2) Call on [exit] to quit the Tcl process
exit 1
} else {
# Non-error write to stderr, proceed as usual
return $bytes
}
}
}
Step 2: Register the interceptor for stderr in interactive shells
if {[info exists ::tcl_interactive]} {
chan push stderr [Bouncer new]
}
Once registered, this will make your interactive shell behave like so:
% puts stderr "Goes, as usual!"
Goes, as usual!
% error "Bye, bye"
Bye, bye
Some remarks
You need to be careful about the Bouncer's write method, the error message has already been massaged for the character encoding (therefore, the fconfigure call).
You might want to put this into a Tcl package or Tcl module, to load the bouncer using package req.
I could imagine that your program writes to stderr and the errorInfo variable happens to be set (as a left-over), this will trigger an unintended exit.

opensplice dds Hello Word Example

I am posting here after asking the question at the openslice dds forum, and not receiving any reply.I am trying to use opensplice dds on a ubuntu machine. I am not sure if it serves as a proof of proper installation, but I have pasted my release.com file below. Now, I was able to run the ping pong example just fine. But when I ran the executable sac_helloworld_pub ( HelloWorld example in the C programming language), I got the following error
vishal#expmach:~/HDE/x86.linux2.6/examples/dcps/HelloWorld/c/standalone$ ./sac_helloworld_pub
Error in DDS_DomainParticipantFactory_create_participant: Creation failed: invalid handle
I did some searching, and it looks like I need to be running the ospl start command from the terminal. But when I do so, I get a No command ospl found message. Below is the release.comfile's contents
echo "<<< OpenSplice HDE Release V6.3.130716OSS For x86.linux2.6, Date 2013-07-30 >>>"
if [ "${SPLICE_ORB:=}" = "" ]
then
SPLICE_ORB=DDS_OpenFusion_1_6_1
export SPLICE_ORB
fi
if [ "${SPLICE_JDK:=}" = "" ]
then
SPLICE_JDK=jdk
export SPLICE_JDK
fi
OSPL_HOME="/home/vishal/HDE/x86.linux2.6"
OSPL_TARGET=x86.linux2.6
PATH=$OSPL_HOME/bin:$PATH
LD_LIBRARY_PATH=$OSPL_HOME/lib${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH
CPATH=$OSPL_HOME/include:$OSPL_HOME/include/sys:${CPATH:=}
OSPL_URI=file://$OSPL_HOME/etc/config/ospl.xml
OSPL_TMPL_PATH=$OSPL_HOME/etc/idlpp
. $OSPL_HOME/etc/java/defs.$SPLICE_JDK
export OSPL_HOME OSPL_TARGET PATH LD_LIBRARY_PATH CPATH OSPL_TMPL_PATH OSPL_URI
$#
release.com (END)
Sorry for the holidays-driven lack of 'reactivity' on the OpenSplice forum .. I've answered your question there though ..
Here's that same answer for completeness:
*For the 6.3 community-edition, the deployment-model changed from shared-memory (v5.x) to the so-called single-process standalone deployment mode where the middleware is simply linked (as libraries) with the application so you don't need to start any daemons first (as was the case for the federated 'shared-memory' mode that was the default in V5).
So its OK that you get the error when trying to call 'ospl' as thats not used anymore so isn't in the distribution.
Now to your issue, your release.com looks OK to me, but perhaps you didn't actually 'source' it in your environment i.e. calling it with a '.' in front of it:
promtp> . release.com
you can verify that by doing an 'echo $OSPL_HOME' in your shell and see if it actually shows the value of the env. variable as set by the release.com.
Hope that helps,
-Hans*

Bad spawn_id while executing expect command

I am writing a script that will copy Valgrind onto whatever shelf that we enter on the command line. The syntax is as follows:
vgrindCopy [shelf number]
For some reason, the files will copy over without any issue, but after the copy completes the follow error is observed:
bad spawn_id (process died earlier?)
while executing
"expect "#""
Here is a copy of the relevant code:
function login_shelf {
expect -c "
set timeout 15
spawn $1
expect \"password:\"
send \"$PW\r\"
expect \"#\"
sleep 1
exit
"
}
# login and make the valgrind directory at /sfs/software/shelf/current
set -- /opt/swe/tools/ext/gnu/valgrind-3.7.0/i686-linux2.6/lib/valgrind/*
login_shelf "/opt/corp/projects/shelftools/bin/app rsync -Lau $* $shelf:/shelf/valgrind"
After playing around with the code, I found that if I remove the line "expect \"#\"", then the program doesn't copy any of the files over anymore. What odd as well is that I'm seeing the issue when I run the script, but a co-worker is not.
Has anyone had a similar issue and determined the cause? Any help would be greatly appreciated as always!
Your code is spawning the rsync and at the expect \"#\" is waiting for rsync to output a #, which it never does, so it exits and expect reports the error.
When you remove the expect \"#\" the expect script exits, terminating the rsync.
Instead of expect \"#\" you should wait for rsync to exit:
expect eof
wait

PHP CLI recording output from interactive SSH session

I've been trying to sort out recording an interactive SSH session via a PHP CLI script. All I really want is sort of like a tee command, where the entire output is recorded into a string.
I've tried most of the commands to execute external processes to get it to work. They either work ok such as passthru and pcntl_exec but don't let me record the output into a string or array, or they don't display any output to my terminal but still accept stuff from STDIN.
I'm wondering if there is a way of having an interactive ssh session i.e, works normally, but actually records the output for use in PHP.
Thanks
<?php
include('Net/SSH2.php');
$ssh = new Net_SSH2('www.domain.tld');
if (!$ssh->login('username', 'password')) {
exit('Login Failed');
}
echo $ssh->read('username#username:~$');
$ssh->write("ls -la\n");
echo $ssh->read('username#username:~$');
?>
You could do something like that.
They either work ok such as passthru
and pcntl_exec but don't let me record
the output into a string or array
Well, you can use a hack to get that string:
ob_start();
passthru('Your command here');
$result=ob_get_clean();
It is bad, but if your server is not high-load - it should work.
Try using ObserveIT, it includes a great SSH and Telnet Recorder that cannot be stopped by powerusers