| Subject: | Net::DNS::Resolver doesn't do sanity checking on nameserver entries with in resolv.conf |
Because Net::DNS::Resolver's resolv.conf parser fails to do any sainty checking on the data being provided to it, some people have been having issues.
The error commonly seen is stuff like: "Bad arg length for Socket::pack_sockaddr_in, length is 0, should be 4 at /usr/local/lib/perl5/5.8.0/i386-freebsd/Socket.pm line 373." etc.
This is caused by the send_udp() function mapping the IPv6 polluted name servers list at $self->{'nameservers'} and attempting to pass an invalid address to inet_aton().
The patch I've attached corrects this pollution by only allowing dotted quad addresses, though it doesn't fully check to see if the address is valid or not, inet_aton should handle that just fine.
--- lib/Net/DNS/Resolver.pm Thu Jun 5 17:42:58 2003
+++ lib/Net/DNS/Resolver.pm Mon Jul 7 15:23:44 2003
@@ -345,9 +345,16 @@
};
/^\s*nameserver\s+(.*)/ && do {
- foreach my $ns (split(' ', $1)) {
- $ns = '0.0.0.0' if $ns eq '0';
- push @ns, $ns;
+ READ_NS: foreach my $ns (split(/\s+/, $1)) {
+ if($ns eq '0'){
+ $ns = '0.0.0.0';
+ } elsif($ns =~ /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/){
+ # Sanity check for IPv4 name servers.
+ push @ns, $ns;
+ } elsif($ns =~ /^[0-9A-Fa-f]{4}\:/){
+ # Appears to be an IPv6 NS, - ignore for now.
+ next READ_NS;
+ }
}
last SWITCH;
};