#!/usr/local/cpanel/3rdparty/bin/perl

# cpanel - scripts/mainipcheck                     Copyright 2022 cPanel, L.L.C.
#                                                           All rights reserved.
# copyright@cpanel.net                                         http://cpanel.net
# This code is subject to the cPanel license. Unauthorized copying is prohibited

use strict;
use warnings;

package scripts::mainipcheck;

use Cpanel::IP::LocalCheck   ();
use Cpanel::IP::Loopback     ();
use Cpanel::Linux::RtNetlink ();
use Cpanel::LoadModule       ();
use Cpanel::Logger           ();
use Cpanel::NAT::Object      ();
use Cpanel::SafeRun::Object  ();
use Cpanel::FileUtils::Write ();
use Cpanel::LoadFile         ();
use Cpanel::DIp::LicensedIP  ();
use Cpanel::Exception        ();
use Socket                   ();

use Try::Tiny;

use Getopt::Long qw(GetOptionsFromArray);

our $MAINIP_FILE = '/var/cpanel/mainip';

exit( __PACKAGE__->script( \@ARGV ) ) unless caller();

sub script {
    my ( $class, $argv ) = @_;

    my $remote_check;
    GetOptionsFromArray(
        $argv,
        'remote-check' => \$remote_check,
    ) if defined $argv and ref $argv eq 'ARRAY';

    my $logger = Cpanel::Logger->new();

    my $mainip_file_contents = eval { Cpanel::LoadFile::loadfile($MAINIP_FILE) // '' };
    my $mainip               = $mainip_file_contents =~ s/\s+//gr;
    my $myip_url             = Cpanel::DIp::LicensedIP::myip_url();
    my $cpIP                 = Cpanel::DIp::LicensedIP::get_license_ip($myip_url);
    my $default_route_ip;
    my $update_mainip      = $mainip ne $mainip_file_contents;    # Clean up formatting of the file if true
    my $mainip_file_exists = -e $MAINIP_FILE;                     # No sense in stat-ing the file twice like we used to in certain scenarioes

    # Needed for NAT awareness, is NO-OP on non-NAT to these values (thus local and public IP values would be the same on non-nat systems).
    my $NAT_obj      = Cpanel::NAT::Object->new();
    my $NAT_local_ip = $NAT_obj->get_local_ip($cpIP);

    if ($remote_check) {
        print "$cpIP\n";
        return 0;
    }

    eval { $default_route_ip = get_ip_from_netlink() || get_ip_from_default_route(); };
    if ( my $error_message = $@ ) {
        chomp $error_message;
        $logger->warn("Encountered an error while determining the main IP from the default route: $error_message");
        ($mainip_file_exists) ? die "/var/cpanel/mainip exists. Bailing out..." : $logger->info("Proceeding with main IP check assuming that the IP address from $myip_url is the main IP address.");
        $default_route_ip = $mainip;    # XXX Should we keep going even here? I'm not sure.
    }
    my $NAT_public_ip = $NAT_obj->get_public_ip($default_route_ip);

    my $canonical_main_ip = $default_route_ip || $NAT_local_ip;
    if ( !$mainip_file_exists ) {
        $update_mainip = 1;             # I'm somewhat curious as to whether we'd wanna update SPF records here too, honestly.
    }
    elsif ( $canonical_main_ip ne $mainip ) {
        $update_mainip = 1;
        $logger->info("The Server's main IP address has changed from $mainip to $canonical_main_ip.");

        # At one point, the below condition turned $default_route_ip into $cpIP, causing logger warns to actually get suppressed
        # when they would normally be spuriously reported for NATted systems.
        # This is because all the check for the logger warn below used to be if $default_route_ip ne $cpIP.
        # This would never be true when we had to update the mainip previously.
        if ( !Cpanel::IP::LocalCheck::ip_is_on_local_server($cpIP) ) {
            $logger->warn("$cpIP is not bound to an interface on the system! Please verify your network configuration.");

            # This can trigger pretty trivially on NAT setups if your cpnat configuration is not built or in fact insane.
            # Just make /var/cpanel/cpnat contain non-ip strings as if they were a key=>value nat IP pair separated
            # by spaces if you want to see this in action.
        }

        # Ensure the license system has what it needs? Not sure how it gets the updated mainip or if it even needs it?
        _reprovision_license_authn();

        require Cpanel::ServerTasks;

        # Update SPF records, as we've changed to a new mainip
        Cpanel::ServerTasks::schedule_task( ['SPFTasks'], 5, 'update_all_users_spf_records' );
        $logger->info("Scheduled SPF record update");
    }

    if ($update_mainip) {
        Cpanel::FileUtils::Write::overwrite( $MAINIP_FILE, $canonical_main_ip, 0644 );
    }

    if ( !$NAT_obj->enabled && $default_route_ip ne $cpIP ) {
        $logger->warn("$myip_url detects system IP as $cpIP and system local IP detected as $default_route_ip. Please verify your network configuration.");
    }
    elsif ( $NAT_obj->enabled && $NAT_public_ip ne $cpIP && $NAT_local_ip ne $default_route_ip ) {

        # Entertaingly enough, in this instance, $NAT_local_ip always equals $cpIP and vice versa. Conveniently enough, it also catches all invalid NAT configs.
        $logger->warn("$myip_url detects a system IP address of $cpIP and system local IP address of $default_route_ip.");
        $logger->warn("This looks like a NAT setup, but these IP addresses do not correspond to values listed in /var/cpanel/cpnat.");
        $logger->info("The system will now rebuild your cpnat configuration to ensure system sanity.");
        _system('/usr/local/cpanel/scripts/build_cpnat');
    }

    return 0;
}

# For mocking in tests -- don't remove the 'uncoverable' comments below, as this impacts Devel::Cover reporting.
sub _system {

    # uncoverable subroutine
    return system @_;    # uncoverable statement
}

# Pick a testing IP and see how the kernel proposes routing it, then look up and return the source address which would be used.
sub get_ip_from_netlink {
    my $TEST_IP   = '208.74.123.2';    # TODO: Better way of picking an IP with high probability of not being routed specially?
    my $result_ip = '';

    try {
        my $routes_ar = Cpanel::Linux::RtNetlink::get_route_to( 'AF_INET', $TEST_IP );
        foreach my $route_info_hr (@$routes_ar) {
            if ( defined $route_info_hr->{'rta_dst'} && $route_info_hr->{'rta_dst'} eq $TEST_IP ) {
                $result_ip = $route_info_hr->{'rta_prefsrc'};
                last;
            }
        }
    }
    catch {
        Cpanel::Logger->new()->warn( 'Failed to retrieve IP via Netlink: ' . Cpanel::Exception::get_string_no_id($_) . "\nFalling back to reading /proc/net/route." );
    };

    return $result_ip;
}

# Get interface associated with default route and use socket() to get IP
sub get_ip_from_default_route {
    my $proc_route_path = shift || '/proc/net/route';    # For unit testing, mostly
    my %interfaces;

    if ( open my $proc_fh, '<', $proc_route_path ) {
        while ( my $line = readline $proc_fh ) {
            chomp $line;
            if ( $line =~ m/^(.+?)\s*0{8}\s.*?(\d+)\s+0{8}\s*(?:\d+\s*){3}$/ ) {
                my ( $interface, $metric ) = ( $1, $2 );
                push @{ $interfaces{$metric} }, $interface;
            }
        }
        close($proc_fh);
    }
    else {
        die("Unable to open $proc_route_path: $!");
    }

    my $lowest_metric = ( sort keys %interfaces )[0];
    my $interface     = $interfaces{$lowest_metric}[0];
    my $ip            = get_ip_from_interface($interface);

    # VPS issues
    if ( Cpanel::IP::Loopback::is_loopback($ip) && $interface =~ /^venet0?$/ ) {
        return get_ip_from_interface('venet0:0');
    }

    return $ip;
}

sub get_ip_from_interface {
    my $interface   = shift;
    my $SIOCGIFADDR = 0x8915;
    my $proto       = getprotobyname('ip');
    socket( my $socket_fh, &Socket::PF_INET, &Socket::SOCK_DGRAM, $proto ) or die("Socket error: $!");

    # struct ifreq is 16 bytes of name, null-padded, followed by 16 bytes of answer.
    my $ifreq = pack( 'a32', $interface );
    ioctl( $socket_fh, $SIOCGIFADDR, $ifreq ) or die("Error in ioctl: $!");
    my ( $if,   $sin )  = unpack( 'a16 a16', $ifreq );
    my ( $port, $addr ) = Socket::sockaddr_in($sin);
    my $ip;
    foreach my $family ( &Socket::AF_INET, &Socket::AF_INET6 ) {
        last if $ip;

        # Generally we'll favor ipv4 addresses over ipv6, but we should use the v6 if it is the only one available.
        $ip = Socket::inet_ntop( $family, $addr );
    }
    return $ip;
}

sub _reprovision_license_authn {

    Cpanel::LoadModule::load_perl_module('Cpanel::Market');
    Cpanel::Market::set_cpstore_is_in_sync_flag(0);
    #
    # This will cause the system to get new LicenseAuthn
    # credentials so we can connect to various cPanel systems
    # that require license-based authentication.
    #
    my $run = Cpanel::SafeRun::Object->new( 'program' => '/usr/local/cpanel/cpkeyclt' );
    warn $run->autopsy() if $run->CHILD_ERROR;

    #
    #  cpkeyclt will auto re-provision on the second run
    #  if the id changes
    #
    $run = Cpanel::SafeRun::Object->new(
        'program' => '/usr/local/cpanel/scripts/try-later',
        'args'    => [
            '--action',      '/usr/local/cpanel/cpkeyclt --quiet',
            '--check',       '/bin/sh -c exit 1',
            '--delay',       11,                                     # We only allow updates every 10 minutes so wait 11
            '--max-retries', 1,
            '--skip-first'
        ]
    );
    warn $run->autopsy() if $run->CHILD_ERROR;

    #
    #  If they changed the ip for the license in manage2 they keep the
    #  same liscid so we need to check after the license update has
    #  happened the second time
    #
    $run = Cpanel::SafeRun::Object->new(
        'program' => '/usr/local/cpanel/scripts/try-later',
        'args'    => [
            '--action',      '/usr/local/cpanel/bin/check_cpstore_in_sync_with_local_storage',
            '--check',       '/bin/sh -c exit 1',
            '--delay',       15,                                                                 # Must happen after the second license update
            '--max-retries', 1,
            '--skip-first'
        ]
    );
    warn $run->autopsy() if $run->CHILD_ERROR;

    return 1;

}