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executable file 500 lines (415 sloc) 9.966 kB
#!/usr/bin/perl
#
# Set PXELINUX hard-coded options
#
use Socket; # For gethostbyname
use Fcntl;
use bytes;
%option_names = (
6 => 'domain-name-servers',
15 => 'domain-name',
54 => 'next-server',
209 => 'config-file',
210 => 'path-prefix',
211 => 'reboottime'
);
@fmt_oneip = ("ip-address", \&parse_oneip, \&show_ip);
@fmt_multiip = ("ip-address-list", \&parse_multiip, \&show_ip);
@fmt_string = ("string", \&parse_string, \&show_string);
@fmt_uint32 = ("uint32", \&parse_uint32, \&show_uint32);
%option_format = (
6 => \@fmt_multiip,
15 => \@fmt_string,
54 => \@fmt_oneip,
67 => \@fmt_string,
209 => \@fmt_string,
210 => \@fmt_string,
211 => \@fmt_uint32
);
sub parse_oneip($)
{
my($s) = @_;
my($name,$aliases,$addrtype,$length,@addrs) = gethostbyname($s);
return ($addrtype == AF_INET) ? $addrs[0] : undef;
}
sub parse_multiip($)
{
my($l) = @_;
my $s;
my @a = ();
my $addr;
my $d = '';
foreach $s (split(/,/, $l)) {
my($name,$aliases,$addrtype,$length,@addrs)
= gethostbyname($s);
if ($addrtype == AF_INET) {
foreach $addr (@addrs) {
$d .= $addr;
}
}
}
return $d ne '' ? $d : undef;
}
sub show_ip($)
{
my($l) = @_;
if (length($l) & 3) {
return undef;
} else {
my @h = ();
my $i;
for ($i = 0; $i < length($l); $i += 4) {
push(@h, inet_ntoa(substr($l, $i, 4)));
}
return join(',', @h);
}
}
sub parse_string($)
{
return $_[0];
}
sub show_string($)
{
my($s) = @_;
my $o, $i, $c;
$o = "\'";
for ($i = 0; $i < length($s); $i++) {
$c = substr($s, $i, 1);
if ($c eq "\'" || $c eq '!') {
$o .= "\'\\$c\'";
} else {
$o .= $c;
}
}
$o .= "\'";
return $o;
}
sub parse_uint32($)
{
my($s) = @_;
if ($s =~ /^[0-9]+$/) {
return pack("N", $s);
} else {
return undef;
}
}
sub show_uint32($)
{
my($l) = @_;
if (length($l) == 4) {
return unpack("N", $l);
} else {
return undef;
}
}
sub parse_generic($)
{
my($s) = @_;
if ($s =~ /^[0-9a-f]{1,2}(:[0-9a-f]{1,2})*$/) {
my $h;
my @b = ();
foreach $h (split(/\:/, $s)) {
push(@b, hex $h);
}
return pack("C", @b);
} else {
return undef;
}
}
sub show_generic($)
{
my($l) = @_;
my $i;
my @h;
for ($i = 0; $i < length($l); $i++) {
push(@h, sprintf("%02x", unpack("C", substr($l, $i, $1))));
}
return join(':', @h);
}
sub parse_option($$)
{
my($opt, $arg) = @_;
my $v;
if (defined($option_format{$opt})) {
$v = $option_format{$opt}[1]($arg);
return $v if (defined($v));
}
return parse_generic($arg);
}
sub show_option($$)
{
my($opt, $arg) = @_;
my $v;
if (defined($option_format{$opt})) {
$v = $option_format{$opt}[2]($arg);
return $v if (defined($v));
}
return show_generic($arg);
}
sub option_number($)
{
my($n) = @_;
if (defined($option_rnames{$n})) {
return $option_rnames{$n};
} elsif ($n =~ /^[0-9]+$/ && $n >= 1 && $n <= 254) {
return $n+0;
} else {
return undef;
}
}
sub read_optsets($)
{
my($file) = @_;
my $data, $bdata, $adata;
my $patch_start = (stat($file))[7];
return undef unless (seek($file, 8, SEEK_SET));
return undef unless (read($file, $data, 7*4) == 7*4);
my($magic, $len, $flags, $boff, $blen, $aoff, $alen)
= unpack("VVVVVVV", $data);
return undef if ($magic != 0x2983c8ac);
return undef if ($len < 7*4);
if ($blen == 0) {
$bdata = '';
} else {
return undef unless (seek($file, $boff, SEEK_SET));
return undef unless (read($file, $bdata, $blen) == $blen);
$patch_start = $boff if ($boff < $patch_start);
}
if ($alen == 0) {
$adata = '';
} else {
return undef unless (seek($file, $aoff, SEEK_SET));
return undef unless (read($file, $adata, $alen) == $alen);
$patch_start = $aoff if ($aoff < $patch_start);
}
return ($patch_start, $bdata, $adata);
}
sub write_optsets($$@)
{
my($file, $patch_start, $bdata, $adata) = @_;
my $boff = 0;
my $aoff = 0;
if (length($bdata) > 0) {
$bdata .= "\xff";
$boff = $patch_start;
return undef unless (seek($file, $boff, SEEK_SET));
return undef unless (print $file $bdata);
$patch_start += length($bdata);
}
if (length($adata) > 0) {
$adata .= "\xff";
$aoff = $patch_start;
return undef unless (seek($file, $aoff, SEEK_SET));
return undef unless (print $file $adata);
$patch_start += length($adata);
}
my $hdr = pack("VVVV", $boff, length($bdata), $aoff, length($adata));
return undef unless (seek($file, 8+3*4, SEEK_SET));
return undef unless (print $file $hdr);
truncate($file, $patch_start);
return 1;
}
sub delete_option($$)
{
my ($num, $block) = @_;
my $o, $l, $c, $x;
$x = 0;
while ($x < length($block)) {
($o, $l) = unpack("CC", substr($block, $x, 2));
if ($o == $num) {
# Delete this option
substr($block, $x, $l+2) = '';
} elsif ($o == 0) {
# Delete a null option
substr($block, $x, 1) = '';
} elsif ($o == 255) {
# End marker - truncate block
$block = substr($block, 0, $x);
last;
} else {
# Skip to the next option
$x += $l+2;
}
}
return $block;
}
sub add_option($$$)
{
my ($num, $data, $block) = @_;
$block = delete_option($num, $block);
if (length($data) == 0) {
return $block;
} elsif (length($data) > 255) {
die "$0: option $num has too much data (max 255 bytes)\n";
} else {
return $block . pack("CC", $num, length($data)) . $data;
}
}
sub list_options($$)
{
my($pfx, $data) = @_;
my $x, $o, $l;
while ($x < length($data)) {
($o, $l) = unpack("CC", substr($data, $x, 2));
if ($o == 0) {
$x++;
} elsif ($o == 255) {
last;
} else {
my $odata = substr($data, $x+2, $l);
last if (length($odata) != $l); # Incomplete option
printf "%s%-20s %s\n", $pfx,
$option_names{$o} || sprintf("%d", $o),
show_option($o, $odata);
$x += $l+2;
}
}
}
sub usage()
{
my $i;
print STDERR "Usage: $0 options pxelinux.0\n";
print STDERR "Options:\n";
print STDERR "--before option value -b Add an option before DHCP data\n";
print STDERR "--after option value -a Add an option after DHCP data\n";
print STDERR "--delete option -d Delete an option\n";
print STDERR "--list -l List set options\n";
print STDERR "--dry-run -n Don't modify the target file\n";
print STDERR "--help -h Display this help text\n";
print STDERR "\n";
print STDERR "The following DHCP options are currently recognized:\n";
printf STDERR "%-23s %-3s %s\n", 'Name', 'Num', 'Value Format';
foreach $i (sort { $a <=> $b } keys(%option_names)) {
printf STDERR "%-23s %3d %s\n",
$option_names{$i}, $i, $option_format{$i}[0];
}
}
%option_rnames = ();
foreach $opt (keys(%option_names)) {
$option_rnames{$option_names{$opt}} = $opt;
}
%before = ();
%after = ();
@clear = ();
$usage = 0;
$err = 0;
$list = 0;
$no_write = 0;
undef $file;
while (defined($opt = shift(@ARGV))) {
if ($opt !~ /^-/) {
if (defined($file)) {
$err = $usage = 1;
last;
}
$file = $opt;
} elsif ($opt eq '-b' || $opt eq '--before') {
$oname = shift(@ARGV);
$odata = shift(@ARGV);
if (!defined($odata)) {
$err = $usage = 1;
last;
}
$onum = option_number($oname);
if (!defined($onum)) {
print STDERR "$0: unknown option name: $oname\n";
$err = 1;
next;
}
$odata = parse_option($onum, $odata);
if (!defined($odata)) {
print STDERR "$0: unable to parse data for option $oname\n";
$err = 1;
next;
}
delete $after{$onum};
$before{$onum} = $odata;
push(@clear, $onum);
} elsif ($opt eq '-a' || $opt eq '--after') {
$oname = shift(@ARGV);
$odata = shift(@ARGV);
if (!defined($odata)) {
$err = $usage = 1;
last;
}
$onum = option_number($oname);
if (!defined($onum)) {
print STDERR "$0: unknown option name: $oname\n";
$err = 1;
next;
}
$odata = parse_option($onum, $odata);
if (!defined($odata)) {
print STDERR "$0: unable to parse data for option $oname\n";
$err = 1;
next;
}
delete $before{$onum};
$after{$onum} = $odata;
push(@clear, $onum);
} elsif ($opt eq '-d' || $opt eq '--delete') {
$oname = shift(@ARGV);
if (!defined($oname)) {
$err = $usage = 1;
last;
}
$onum = option_number($oname);
if (!defined($onum)) {
print STDERR "$0: unknown option name: $oname\n";
$err = 1;
next;
}
push(@clear, $onum);
delete $before{$onum};
delete $after{$onum};
} elsif ($opt eq '-n' || $opt eq '--no-write' || $opt eq '--dry-run') {
$no_write = 1;
} elsif ($opt eq '-l' || $opt eq '--list') {
$list = 1;
} elsif ($opt eq '-h' || $opt eq '--help') {
$usage = 1;
} else {
print STDERR "Invalid option: $opt\n";
$err = $usage = 1;
}
}
if (!defined($file) && !$usage) {
$err = $usage = 1;
}
if ($usage) {
usage();
}
if ($err || $usage) {
exit($err);
}
if (!scalar(@clear)) {
$no_write = 1; # No modifications requested
}
$mode = $no_write ? '<' : '+<';
open(FILE, $mode, $file)
or die "$0: cannot open: $file: $!\n";
($patch_start, @data) = read_optsets(\*FILE);
if (!defined($patch_start)) {
die "$0: $file: patch block not found or file corrupt\n";
}
foreach $o (@clear) {
$data[0] = delete_option($o, $data[0]);
$data[1] = delete_option($o, $data[1]);
}
foreach $o (keys(%before)) {
$data[0] = add_option($o, $before{$o}, $data[0]);
}
foreach $o (keys(%after)) {
$data[1] = add_option($o, $after{$o}, $data[1]);
}
if ($list) {
list_options('-b ', $data[0]);
list_options('-a ', $data[1]);
}
if (!$no_write) {
if (!write_optsets(\*FILE, $patch_start, @data)) {
die "$0: $file: failed to write options: $!\n";
}
}
close(FILE);
exit 0;
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