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Add nat46 in-kernel translator support #36

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Nov 7, 2023
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Add nat46 in-kernel translator support #36

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8 changes: 5 additions & 3 deletions README.pod
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Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,11 @@ SIIT-DC Edge Relay, you will probably want to manually configure the settings
I<clat-v4-addr>, I<clat-v6-addr>, and I<plat-prefix> to mirror the SIIT-DC
Border Relay's configuration.

It relies on the software package TAYGA by Nathan Lutchansky for the actual
translation of packets between IPv4 and IPv6 (I<RFC 6145>) TAYGA may be
downloaded from its home page at L<http://www.litech.org/tayga/>.
It relies either on the software package TAYGA by Nathan Lutchansky or on the
kernel module nat46 by Andrew Yourtchenko for the actual translation of packets
between IPv4 and IPv6 (I<RFC 6145>) TAYGA may be downloaded from its home page
at L<http://www.litech.org/tayga/>, nat46 from its repository at
L<https://github.com/ayourtch/nat46>.

=head1 SYNOPSIS

Expand Down
147 changes: 99 additions & 48 deletions clatd
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Expand Up @@ -26,7 +26,7 @@
use strict;
use Net::IP;

my $VERSION = "1.6";
my $VERSION = "1.6nat46";

#
# Populate the global config hash with the default values
Expand Down Expand Up @@ -438,6 +438,15 @@ sub is_modified_eui64 {
return ($ip & $mask) != $mask;
}

sub cleanup_handler {
p("Cleaning up and exiting");
if(cfg("script-down")) {
d("Running custom shutdown script: ", cfg("script-down"));
cmd(\&err, cfg("script-down"));
}
cleanup_and_exit(0);
}


#
# This function considers any globally scoped IPv6 address on the PLAT-facing
Expand Down Expand Up @@ -577,7 +586,8 @@ sub get_clat_v6_addr {
# below gets set as we go along, so that the cleanup subroutine can restore
# stuff if necessary.
#
my $cleanup_remove_clat_dev; # true if having created it
my $cleanup_remove_tayga_clat_dev; # true if having created it
my $cleanup_remove_nat46_clat_dev; # true if having created it
my $cleanup_delete_taygaconf; # true if having made a temp confile
my $cleanup_zero_forwarding_sysctl; # zero forwarding sysctl if set
my @cleanup_accept_ra_sysctls; # accept_ra sysctls to be reset to '1'
Expand All @@ -589,15 +599,23 @@ my @cleanup_restore_v4_defaultroutes; # temporarily replaced defaultroutes
sub cleanup_and_exit {
my $exitcode = shift;

if(defined($cleanup_remove_clat_dev)) {
d("Cleanup: Removing CLAT device");
if(defined($cleanup_remove_tayga_clat_dev)) {
d("Cleanup: Removing TAYGA CLAT device");
cmd(\&w, cfg("cmd-tayga"), "--config", cfg("tayga-conffile"), "--rmtun");
}
if(defined($cleanup_delete_taygaconf)) {
d("Cleanup: Deleting TAYGA config file '", cfg("tayga-conffile"), "'");
unlink(cfg("tayga-conffile"))
or w("unlink('", cfg("tayga-conffile"), "') failed");
}
if(defined($cleanup_remove_nat46_clat_dev)) {
d("Cleanup: Removing nat46 CLAT device");
my $nat46_control_fh;
open($nat46_control_fh, ">/proc/net/nat46/control") or
err("Could not open nat46 control socket for writing");
print $nat46_control_fh "del ", cfg("clat-dev"), "\n";
close($nat46_control_fh) or err("close($nat46_control_fh: $!");
}
if(defined($cleanup_zero_forwarding_sysctl)) {
d("Cleanup: Resetting forwarding sysctl to 0");
sysctl("net/ipv6/conf/all/forwarding", 0);
Expand Down Expand Up @@ -772,35 +790,40 @@ if(cfgbool("v4-conncheck-enable") and !cfgbool("v4-defaultroute-replace")) {
d("Skipping IPv4 connectivity check at user request");
}

# Let's figure out if there's nat46 kernel module loaded
my $nat46_controlfile = "/proc/net/nat46/control";
my $use_nat46 = (-e $nat46_controlfile);



#
# Write out the TAYGA config file, either to the user-specified location,
# or to a temporary file (which we'll delete later)
#
my $tayga_conffile = cfg("tayga-conffile");
my $tayga_conffile_fh;
if(!$tayga_conffile) {
require File::Temp;
($tayga_conffile_fh, $tayga_conffile) = File::Temp::tempfile();
d2("Using temporary conffile for TAYGA: $tayga_conffile");
$CFG{"tayga-conffile"} = $tayga_conffile;
$cleanup_delete_taygaconf = 1;
} else {
open($tayga_conffile_fh, ">$tayga_conffile") or
err("Could not open TAYGA config file '$tayga_conffile' for writing");
}

print $tayga_conffile_fh "# Ephemeral TAYGA config file written by $0\n";
print $tayga_conffile_fh "# This file may be safely deleted at any time.\n";
print $tayga_conffile_fh "tun-device ", cfg("clat-dev"), "\n";
print $tayga_conffile_fh "prefix ", cfg("plat-prefix"), "\n";
print $tayga_conffile_fh "ipv4-addr ", cfg("tayga-v4-addr"), "\n";
print $tayga_conffile_fh "map ", cfg("clat-v4-addr"), " ",
cfg("clat-v6-addr"),"\n";
unless($use_nat46) {
my $tayga_conffile = cfg("tayga-conffile");
my $tayga_conffile_fh;
if(!$tayga_conffile) {
require File::Temp;
($tayga_conffile_fh, $tayga_conffile) = File::Temp::tempfile();
d2("Using temporary conffile for TAYGA: $tayga_conffile");
$CFG{"tayga-conffile"} = $tayga_conffile;
$cleanup_delete_taygaconf = 1;
} else {
open($tayga_conffile_fh, ">$tayga_conffile") or
err("Could not open TAYGA config file '$tayga_conffile' for writing");
}

close($tayga_conffile_fh) or err("close($tayga_conffile_fh: $!");
print $tayga_conffile_fh "# Ephemeral TAYGA config file written by $0\n";
print $tayga_conffile_fh "# This file may be safely deleted at any time.\n";
print $tayga_conffile_fh "tun-device ", cfg("clat-dev"), "\n";
print $tayga_conffile_fh "prefix ", cfg("plat-prefix"), "\n";
print $tayga_conffile_fh "ipv4-addr ", cfg("tayga-v4-addr"), "\n";
print $tayga_conffile_fh "map ", cfg("clat-v4-addr"), " ",
cfg("clat-v6-addr"),"\n";

close($tayga_conffile_fh) or err("close($tayga_conffile_fh: $!");
}
#
# Enable IPv6 forwarding if necessary
#
Expand Down Expand Up @@ -861,9 +884,18 @@ if(cfgbool("proxynd-enable")) {
# route to the corresponding IPv6 address, and possibly an IPv4 default route
#
p("Creating and configuring up CLAT device '", cfg("clat-dev"), "'");
cmd(\&err, cfg("cmd-tayga"), "--config", cfg("tayga-conffile"), "--mktun",
cfgint("debug") ? "-d" : "");
$cleanup_remove_clat_dev = 1;
if($use_nat46) {
my $nat46_control_fh;
open($nat46_control_fh, ">$nat46_controlfile") or
err("Could not open nat46 control socket for writing");
print $nat46_control_fh "add ", cfg("clat-dev"), "\n";
close($nat46_control_fh) or err("close($nat46_control_fh: $!");
$cleanup_remove_nat46_clat_dev = 1;
} else {
cmd(\&err, cfg("cmd-tayga"), "--config", cfg("tayga-conffile"), "--mktun",
cfgint("debug") ? "-d" : "");
$cleanup_remove_tayga_clat_dev = 1;
}
cmd(\&err, cfg("cmd-ip"), qw(link set up dev), cfg("clat-dev"));
cmd(\&err, cfg("cmd-ip"), qw(-4 address add), cfg("clat-v4-addr"),
"dev", cfg("clat-dev"));
Expand Down Expand Up @@ -908,30 +940,49 @@ if(cfg("script-up")) {
}

#
# All preparation done! We can now start TAYGA, which will handle the actual
# All preparation done! We can now start nat46 or TAYGA, which will handle the actual
# translation of IP packets.
#
p("Starting up TAYGA, using config file '$tayga_conffile'");
if($use_nat46){
p("Setting up nat46 kernel module");
my $nat46_control_fh;
open($nat46_control_fh, ">$nat46_controlfile") or
err("Could not open nat46 control socket for writing");
print $nat46_control_fh "config ", cfg("clat-dev"), " local.style NONE\n";
print $nat46_control_fh "config ", cfg("clat-dev"), " local.v4 ", cfg("clat-v4-addr"), "/32\n";
print $nat46_control_fh "config ", cfg("clat-dev"), " local.v6 ", cfg("clat-v6-addr"), "/128\n";
print $nat46_control_fh "config ", cfg("clat-dev"), " remote.style RFC6052\n";
print $nat46_control_fh "config ", cfg("clat-dev"), " remote.v6 ", cfg("plat-prefix"), "\n";
close($nat46_control_fh) or err("close($nat46_control_fh: $!");

# Nothing more to do here, we just set up a cleanup handler and sleep forever.
$SIG{'INT'} = \&cleanup_handler;
$SIG{'TERM'} = \&cleanup_handler;
sleep();
} else {
my $tayga_conffile = cfg("tayga-conffile");
p("Starting up TAYGA, using config file '$tayga_conffile'");

# We don't want systemd etc. to actually kill this script when stopping the
# service, just TAYGA (so that we can get around to cleaning up after
# ourselves)
$SIG{'INT'} = 'IGNORE';
$SIG{'TERM'} = 'IGNORE';
# We don't want systemd etc. to actually kill this script when stopping the
# service, just TAYGA (so that we can get around to cleaning up after
# ourselves)
$SIG{'INT'} = 'IGNORE';
$SIG{'TERM'} = 'IGNORE';

cmd(\&err, cfg("cmd-tayga"), "--config", cfg("tayga-conffile"), "--nodetach",
cfgint("debug") ? "-d" : "");
p("TAYGA terminated, cleaning up and exiting");
cmd(\&err, cfg("cmd-tayga"), "--config", cfg("tayga-conffile"), "--nodetach",
cfgint("debug") ? "-d" : "");
p("TAYGA terminated, cleaning up and exiting");

$SIG{'INT'} = 'DEFAULT';
$SIG{'TERM'} = 'DEFAULT';
$SIG{'INT'} = 'DEFAULT';
$SIG{'TERM'} = 'DEFAULT';

#
# TAYGA exited, probably because we're shutting down. Run the down script, then
# cleanup and exit.
#
if(cfg("script-down")) {
d("Running custom shutdown script: ", cfg("script-down"));
cmd(\&err, cfg("script-down"));
#
# TAYGA exited, probably because we're shutting down. Run the down script, then
# cleanup and exit.
#
if(cfg("script-down")) {
d("Running custom shutdown script: ", cfg("script-down"));
cmd(\&err, cfg("script-down"));
}
cleanup_and_exit(0);
}
cleanup_and_exit(0);