A friend of mine asked me to do a simple script that would consume IRC's (RFC 1459) pseudo BNF and map it directly to a GET request that is sent to an application server. This is what I came up within few hours.

It was a real pleasure since I haven't done a lot of www programming with Perl. I am open to all suggestions how this kind of stuff is usually done and all pointers to previous art are appreciated.

#! /usr/bin/perl

use strict;
use warnings;
use HTTP::Lite;
use English qw( -no_match_vars );

{
    usage() if @ARGV != 2;
    
    # Note, if you want to define the port the <domain:port>
    # has to contain trailing slash, eg.
    #  http://foo.bar.com:80/
    #  http://foo.bar.com:80/my/remote/app
    
    my $url = shift;
    my $bnf = shift;
    
    my @items = split(/\s+/, $bnf);
    my @bnf = ();

    # Leave the possible 15th parameter untouched.
    for(my $i = 0; $i < 16; $i++ ) {
        push @bnf, shift @items;
    }    

    # The last param may contain whitespaces etc.
    push @bnf, join(' ', @items);
    
    my $ret = http_get_request_from_bnf($url, @bnf);

    die "Server failed to serve our request '$url' : $ret" 
        if $ret !~ /2\d{1,2}/;

    print "$ret\n";
}

sub http_get_request_from_bnf {

    my $url = shift;
    my @bnf_items = @_;
    my $i = 1;

    my $prefix = shift @bnf_items;
    my $command = shift @bnf_items;

    my $http = new HTTP::Lite;
    
    $http->add_req_header('Prefix', $prefix);
    $http->add_req_header('Command', $command);
    
    foreach my $item ( @bnf_items ) {
        $http->add_req_header("Param$i", $item);
        $i++;
    }

    #use Data::Dumper;
    #print Dumper($http);
    
    my $request = $http->request($url)
        or die "Unable to create GET request : $OS_ERROR\n";

    return $request;
}

sub usage {

    print<<EOL;

usage: $PROGRAM_NAME <url> <Pseudo BNF command>

URL must contain trailing slash and the port number can be included, e
+g.

    http://foo.bar.com:80/
    http://www.baz.com:80/my/remote/app

EOL
    exit 1;
}
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