PERL Miscellaneous - perl tcp server script works, but no data.

Author

perl tcp server script works, but no data.

Eli Sidwell

2004-05-19, 3:32 pm

I am trying to get the following script to accept data, but I never see any.
Is this a flushing issue ?

Any help is appreciated.

#!/usr/bin/perl -w

$server_port = "5001";

use IO::Socket;

# make the socket
$server = IO::Socket::INET->new(LocalPort => $server_port,
Type => SOCK_STREAM,
Proto => 'tcp',
Reuse => 1,
Listen => 10 ) # or SOMAXCONN
or die "Couldn't be a tcp server on port $server_port : $@\n";

$server->autoflush();

while ($client = $server->accept()) {
# $client is the new connection

$client->recv($str, 1024)
or die "Can't recv: $!\n";

$client_ip = $client->peerhost;
$client_port = $client->peerport;

print "Data is: $str \n";
print "Client IP: $client_ip\n";
print "Client port: $client_port\n";
}

close($server);

Jim Gibson

2004-05-19, 5:35 pm

In article <ef9a95b0.0405191046.6ef2960e@posting.google.com>, Eli
Sidwell <sidwelle@alexian.net> wrote:

> I am trying to get the following script to accept data, but I never see any.
> Is this a flushing issue ?
>
> Any help is appreciated.
>
>
> #!/usr/bin/perl -w
>
> $server_port = "5001";
>
> use IO::Socket;
>
> # make the socket
> $server = IO::Socket::INET->new(LocalPort => $server_port,
> Type => SOCK_STREAM,
> Proto => 'tcp',
> Reuse => 1,
> Listen => 10 ) # or SOMAXCONN
> or die "Couldn't be a tcp server on port $server_port : $@\n";
>
> $server->autoflush();
>
> while ($client = $server->accept()) {
> # $client is the new connection
>
> $client->recv($str, 1024)
> or die "Can't recv: $!\n";

recv() is for UDP messages. You have specified a TCP connection. Try

my $nread = $client->read($str,1024);
die "Can't read from socket: $!" unless defined $nread;

instead.

>
> $client_ip = $client->peerhost;
> $client_port = $client->peerport;
>
> print "Data is: $str \n";
> print "Client IP: $client_ip\n";
> print "Client port: $client_port\n";
> }
>
> close($server);

You have not shown the client program, so there could be a problem
there as well.

Eli Sidwell

2004-05-20, 12:32 pm

Still nothing, the $nread even comes up 0.

As far as the client, I tried to telnet a small file to that port and
then I wrote an app using the VB winsock to move text to that port.
Both times it opens the port and accepts the data (I think), I can get
the port and IP from perl but, I don't see any data.

Are there any good reference books on the perl socket with examples.
I have the orilly cookbook, but its a lot of theory.

Thanks

Jim Gibson <jgibson@mail.arc.nasa.gov> wrote in message news:<190520041320228983%jgibson@mail.arc.nasa.gov>...
> In article <ef9a95b0.0405191046.6ef2960e@posting.google.com>, Eli
> Sidwell <sidwelle@alexian.net> wrote:
>
>
> recv() is for UDP messages. You have specified a TCP connection. Try
>
> my $nread = $client->read($str,1024);
> die "Can't read from socket: $!" unless defined $nread;
>
> instead.
>
>
> You have not shown the client program, so there could be a problem
> there as well.

Kevin Collins

2004-05-20, 8:31 pm

In article <ef9a95b0.0405200724.2b8f1e58@posting.google.com>, Eli Sidwell
wrote:

Please, no top posting...

> Still nothing, the $nread even comes up 0.
>
> As far as the client, I tried to telnet a small file to that port and
> then I wrote an app using the VB winsock to move text to that port.
> Both times it opens the port and accepts the data (I think), I can get
> the port and IP from perl but, I don't see any data.
>
> Are there any good reference books on the perl socket with examples.
> I have the orilly cookbook, but its a lot of theory.
>
-snip-

perldoc 'perlipc' has a basic TCP client/server that I have used as the basis
for a couple of different things. Its not too complex.

Kevin

Anno Siegel

2004-05-21, 6:31 am

Kevin Collins <spamtotrash@toomuchfiction.com> wrote in comp.lang.perl.misc:
> In article <ef9a95b0.0405200724.2b8f1e58@posting.google.com>, Eli Sidwell
> wrote:
>
> Please, no top posting...
>
> -snip-
>
> perldoc 'perlipc' has a basic TCP client/server that I have used as the basis
> for a couple of different things. Its not too complex.

There's also Net::EasyTCP which covers simple TCP-based client/server
pairs.

Anno

Eli Sidwell

2004-05-21, 11:31 pm

anno4000@lublin.zrz.tu-berlin.de (Anno Siegel) wrote in message news:<c8kgsg$smk$3@mamenchi.zrz.TU-Berlin.DE>...
> Kevin Collins <spamtotrash@toomuchfiction.com> wrote in comp.lang.perl.misc:
>
> There's also Net::EasyTCP which covers simple TCP-based client/server
> pairs.
>
> Anno

I think that I have narrowed the problem, it seems that I don't
receive any data unless I send more than a 2k of stuff. I have seen
some postings that refer to flushing issues, how do I cause this code
to flush no matter what size data is received?

Thanks

Ben Morrow

2004-05-22, 12:31 am

Quoth sidwelle@alexian.net (Eli Sidwell):
> I think that I have narrowed the problem, it seems that I don't
> receive any data unless I send more than a 2k of stuff. I have seen
> some postings that refer to flushing issues, how do I cause this code
> to flush no matter what size data is received?

This sounds like a problem on the sending end... you need to flush after
each write. In perl, set $|=1.

Ben

--
Outside of a dog, a book is a man's best friend.
Inside of a dog, it's too dark to read.
ben@morrow.me.uk Groucho Marx

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