#!/usr/bin/perl

$radvd_conf = "/etc/radvd.conf" ;
$radvd_pidfile = "/var/run/radvd/radvd.pid" ;
$old_prefix_file = "/var/run/dhcpv6/prefix.dat" ;
$resolv_conf="/etc/resolv.conf" ;

# code to update resolv.conf is crude; should preseve existing
# IPv4 entries but won't purge stale IPv6 ones

if (open (IN,$old_prefix_file)) {
  $old_prefix = (<IN>) ; 
  chomp($old_prefix) ;
  close (IN) ;
}

$date = localtime() ;
if ($ENV{new_iapd}) {
  unless ($old_prefix eq $ENV{new_iapd}) {
    open (PFX,">$old_prefix_file") ;
    print PFX "$ENV{new_iapd}\n" ;
    close (PFX) ;
    if ($ENV{new_iapd} =~ /([\da-f:]+)\/([\d]+),pltime=([\d]+),vltime=([\d]+)/) {
      $prefix = $1 ; $width = $2 ; $pltime = $3 ; $vltime = $4 ;
      unless (open (RDV,">$radvd_conf")) {
        exit 1 ;
      }
      print RDV<<EOT;
interface eth0 {
  AdvSendAdvert on;
  MinRtrAdvInterval 30;
  MaxRtrAdvInterval 100;
  AdvDefaultLifetime 300;
  prefix $prefix/64 {
    AdvOnLink on;
    AdvAutonomous on;
    AdvRouterAddr off;
    AdvValidLifetime $vltime;
    AdvPreferredLifetime $pltime;
  };
};
EOT
      open (IN,$radvd_pidfile) or die "Can't open $radvd_pidfile\n" ;
      $radvd_pid = <IN> ; chomp($radvd_pid) ;
      kill "HUP", $radvd_pid ;
    }
  }
}
if ($ENV{new_domain_name_servers}) {
  open (IN,$resolv_conf) ;
  while (<IN>) {
    chomp ;
    if (/nameserver[\s]+([\da-f:]{8,20})/) {
      $ns6{$1}++ ;
    }
  }
  close(IN) ;
  foreach $ns (split(' ',$ENV{new_domain_name_servers})) {
    unless ($ns6{$ns}) { push (@ns6,$ns) ; } 
  }
  if (@ns6) {
    open (NS,">>$resolv_conf") ;
    foreach $ns (@ns6) {
      print NS "nameserver $ns\n" ;
    }
    close(NS) ;
  }
}
exit 0;