NAME¶
LWPx::ParanoidAgent - subclass of LWP::UserAgent that protects you from harm
SYNOPSIS¶
require LWPx::ParanoidAgent;
my $ua = LWPx::ParanoidAgent->new;
# this is 10 seconds overall, from start to finish. not just between
# socket reads. and it includes all redirects. so attackers telling
# you to download from a malicious tarpit webserver can only stall
# you for $n seconds
$ua->timeout(10);
# setup extra block lists, in addition to the always-enforced blocking
# of private IP addresses, loopbacks, and multicast addresses
$ua->blocked_hosts(
"foo.com",
qr/\.internal\.company\.com$/i,
sub { my $host = shift; return 1 if is_bad($host); },
);
$ua->whitelisted_hosts(
"brad.lj",
qr/^192\.168\.64\.3?/,
sub { ... },
);
# get/set the DNS resolver object that's used
my $resolver = $ua->resolver;
$ua->resolver(Net::DNS::Resolver->new(...));
# and then just like a normal LWP::UserAgent, because it is one.
my $response = $ua->get('http://search.cpan.org/');
...
if ($response->is_success) {
print $response->content; # or whatever
}
else {
die $response->status_line;
}
DESCRIPTION¶
The "LWPx::ParanoidAgent" is a class subclassing
"LWP::UserAgent", but paranoid against attackers. It's to be used
when you're fetching a remote resource on behalf of a possibly malicious user.
This class can do whatever "LWP::UserAgent" can (callbacks, uploads
from files, etc), except proxy support is explicitly removed, because in that
case you should do your paranoia at your proxy.
Also, the schemes are limited to http and https, which are mapped to
"LWPx::Protocol::http_paranoid" and
"LWPx::Protocol::https_paranoid", respectively, which are forked
versions of the same ones without the "_paranoid". Subclassing them
didn't look possible, as they were essentially just one huge function.
This class protects you from connecting to internal IP ranges (unless you
whitelist them), hostnames/IPs that you blacklist, remote webserver tarpitting
your process (the timeout parameter is changed to be a global timeout over the
entire process), and all combinations of redirects and DNS tricks to otherwise
tarpit and/or connect to internal resources.
CONSTRUCTOR¶
- "new"
- my $ua = LWPx::ParanoidAgent->new([ %opts ]);
In addition to any constructor options from LWP::UserAgent, you may also set
"blocked_hosts" (to an arrayref), "whitelisted_hosts"
(also an arrayref), and "resolver", a Net::DNS::Resolver
object.
METHODS¶
- $csr->resolver($net_dns_resolver)
- $csr->resolver
- Get/set the Net::DNS::Resolver object used to lookup hostnames.
- $csr->blocked_hosts(@host_list)
- $csr->blocked_hosts
- Get/set the the list of blocked hosts. The items in @host_list may be
compiled regular expressions (with qr//), code blocks, or scalar literals.
In any case, the thing that is match, passed in, or compared
(respectively), is all of the given hostname, given IP address, and IP
address in canonical a.b.c.d decimal notation. So if you want to block
"1.2.3.4" and the user entered it in a mix of network/host form
in a mix of decimal/octal/hex, you need only block "1.2.3.4" and
not worry about the details.
- $csr->whitelisted_hosts(@host_list)
- $csr->whitelisted_hosts
- Like blocked hosts, but matching the hosts/IPs that bypass blocking
checks. The only difference is the IP address isn't canonicalized before
being whitelisted-matched, mostly because it doesn't make sense for
somebody to enter in a good address in a subversive way.
SEE ALSO¶
See LWP::UserAgent to see how to use this class.
http://contributing.appspot.com/lwpx-paranoidagent
http://brad.livejournal.com/2409049.html
https://github.com/collectiveintel/LWPx-ParanoidAgent
http://search.cpan.org/dist/LWPx-ParanoidAgent
ISSUES¶
Report issues:
https://github.com/collectiveintel/LWPx-ParanoidAgent/issues
WARRANTY¶
This module is supplied "as-is" and comes with no warranty, expressed
or implied. It tries to protect you from harm, but maybe it will. Maybe it
will destroy your data and your servers. You'd better audit it and send me bug
reports.
BUGS¶
Maybe. See the warranty above.
COPYRIGHT¶
Copyright 2005 Brad Fitzpatrick
Copyright 2013 Wes Young (wesyoung.me)
Lot of code from the the base class, copyright 1995-2004 Gisle Aas.
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.