Socket:INET + Pipe to external program

Posted on 2004-08-01
Last Modified: 2008-03-03
i want to write a perl file that starts a ftp program and then a udp server that listens for commands to send to the ftp program.

For tetsing purpose i used:
open(FTP, "|/home/user1/ftp/bin/ftp");
print FTP "open ftp://user:pass@";

So far everything works fine.
But if I add the INET Socket part it does not work anymore:

use IO::Socket::INET;
my $PASSWORD = 'test';open(FTP, "|/home/user1/ftp/bin/ftp") ;
my $sock = new IO::Socket::INET(LocalPort => 45720,Proto => "udp") || die @!;
printf "Waiting for message..\n";
while ($sock->recv($buf, 1024)) {
        chomp $buf;
        my ($password, $rcmd) = split(/ /, $buf);
        if ($password ne $PASSWORD) {
                printf "Wrong password from client (%s), ignoring request ..\n", $password;
        print FTP "open ftp://user:pass@";
        printf "New message .. %s \n",  $rcmd;
        printf "Waiting for next message..\n";
print FTP "quit";
exit 0;

This does not work as i thought it would.
I think the ftp program gets started (using ps -aux tells me it is running) but the line:
print FTP "open ftp://user:pass@";
is not sent to the program for some reason.

To avoid unnecessary questions:
I use: print FTP "open ftp://user:pass@";
for testing purpose later it should be print FTP "$rcmd"

Thank you
Question by:Bug2k3
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LVL 28

Expert Comment

ID: 11689237
Why not use the Net::FTP module instead of the pipe to the external prgram?  The module will give you better control of the FTP connection, and provides error status and handling.

Author Comment

ID: 11689286
The external program comes with some extra functions the NET::FTP module does not have.
LVL 28

Expert Comment

ID: 11689319
What functions do you need?  The FTP module has some functions that are available to it but are not listed because they are inherited from Net::Netrc, Net::Cmd, and IO::Socket::INET.  Could those inherited functions be the ones you need?
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Author Comment

ID: 11689352
Believe me, the things I use are not included in those components/modules.
And my question is not limited to ftp programs but to all command line applications in combination with the Socket:INET Server.
LVL 20

Accepted Solution

jmcg earned 500 total points
ID: 11690608
You got this to work without sending line terminations down the pipe to the FTP command? That seems anomalous.

If it's necessary to use this external FTP application, you might prefer to run it under the control of something like the Expect module. When you send commands down the pipe, there is no reverse communication channel to see the results in your program.


Author Comment

ID: 11691462
Thanks for your answers. I solved the problem by disabling the puffering.
my $oldfh = select(FTP);
$| = 1;
I also added the line terminations and now it works fine.

So i think this problem is solved.
LVL 20

Expert Comment

ID: 11693408
Buffering was to be the next suspect, but I couldn't point a finger at it in the presence of your claim to have things working in that first example.

Since you've mostly solved this problem without our help, do you want to have this question PAQed and your points refunded?

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