linux-yocto/lib/build_OID_registry

#!/usr/bin/perl -w

Build a static ASN.1 Object Identified (OID) registry

Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.

Written by David Howells (dhowells@redhat.com)

This program is free software; you can redistribute it and/or

modify it under the terms of the GNU General Public Licence

as published by the Free Software Foundation; either version

2 of the Licence, or (at your option) any later version.

use strict;

my @names = (); my @oids = ();

if ($#ARGV != 1) { print STDERR "Format: ", $0, " \n"; exit(2); }

Open the file to read from

open IN_FILE, "<$ARGV[0]" || die; while (<IN_FILE>) { chomp; if (m!\s+OID_([a-zA-z][a-zA-Z0-9_]+),\s+/[]\s+([012][.0-9])\s+[*]/!) { push @names, $1; push @oids, $2; } } close IN_FILE || die;

Open the files to write into

open C_FILE, ">$ARGV[1]" or die; print C_FILE "/*\n"; print C_FILE " * Automatically generated by ", $0, ". Do not edit\n"; print C_FILE " */\n";

Split the data up into separate lists and also determine the lengths of the

encoded data arrays.

my @indices = (); my @lengths = (); my $total_length = 0;

print "Compiling ", $#names + 1, " OIDs\n";

for (my $i = 0; $i <= $#names; $i++) { my $name = $names[$i]; my $oid = $oids[$i];

my @components = split(/[.]/, $oid);

# Determine the encoded length of this OID
my $size = $#components;
for (my $loop = 2; $loop <= $#components; $loop++) {
my $c = $components[$loop];

# We will base128 encode the number
my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
$tmp = int($tmp / 7);
$size += $tmp;
}
push @lengths, $size;
push @indices, $total_length;
$total_length += $size;

}

Emit the look-up-by-OID index table

print C_FILE "\n"; if ($total_length <= 255) { print C_FILE "static const unsigned char oid_index[OID__NR + 1] = {\n"; } else { print C_FILE "static const unsigned short oid_index[OID__NR + 1] = {\n"; } for (my $i = 0; $i <= $#names; $i++) { print C_FILE "\t[OID_", $names[$i], "] = ", $indices[$i], ",\n" } print C_FILE "\t[OID__NR] = ", $total_length, "\n"; print C_FILE "};\n";

Encode the OIDs

my @encoded_oids = ();

for (my $i = 0; $i <= $#names; $i++) { my @octets = ();

my @components = split(/[.]/, $oids[$i]);

push @octets, $components[0] * 40 + $components[1];

for (my $loop = 2; $loop <= $#components; $loop++) {
my $c = $components[$loop];

# Base128 encode the number
my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
$tmp = int($tmp / 7);

for (; $tmp > 0; $tmp--) {
    push @octets, (($c >> $tmp * 7) & 0x7f) | 0x80;
}
push @octets, $c & 0x7f;
}

push @encoded_oids, \@octets;

}

Create a hash value for each OID

my @hash_values = (); for (my $i = 0; $i <= $#names; $i++) { my @octets = @{$encoded_oids[$i]};

my $hash = $#octets;
foreach (@octets) {
$hash += $_ * 33;
}

$hash = ($hash >> 24) ^ ($hash >> 16) ^ ($hash >> 8) ^ ($hash);

push @hash_values, $hash & 0xff;

}

Emit the OID data

print C_FILE "\n"; print C_FILE "static const unsigned char oid_data[", $total_length, "] = {\n"; for (my $i = 0; $i <= $#names; $i++) { my @octets = @{$encoded_oids[$i]}; print C_FILE "\t"; print C_FILE $_, ", " foreach (@octets); print C_FILE "\t// ", $names[$i]; print C_FILE "\n"; } print C_FILE "};\n";

Build the search index table (ordered by length then hash then content)

my @index_table = ( 0 .. $#names );

@index_table = sort { my @octets_a = @{$encoded_oids[$a]}; my @octets_b = @{$encoded_oids[$b]};

return $hash_values[$a] <=> $hash_values[$b]
if ($hash_values[$a] != $hash_values[$b]);
return $#octets_a <=> $#octets_b
if ($#octets_a != $#octets_b);
for (my $i = $#octets_a; $i >= 0; $i--) {
return $octets_a[$i] <=> $octets_b[$i]
    if ($octets_a[$i] != $octets_b[$i]);
}
return 0;

} @index_table;

Emit the search index and hash value table

print C_FILE "\n"; print C_FILE "static const struct {\n"; print C_FILE "\tunsigned char hash;\n"; if ($#names <= 255) { print C_FILE "\tenum OID oid : 8;\n"; } else { print C_FILE "\tenum OID oid : 16;\n"; } print C_FILE "} oid_search_table[OID__NR] = {\n"; for (my $i = 0; $i <= $#names; $i++) { my @octets = @{$encoded_oids[$index_table[$i]]}; printf(C_FILE "\t[%3u] = { %3u, OID_%-35s }, // ", $i, $hash_values[$index_table[$i]], $names[$index_table[$i]]); printf C_FILE "%02x", $_ foreach (@octets); print C_FILE "\n"; } print C_FILE "};\n";

Emit the OID debugging name table

#print C_FILE "\n"; #print C_FILE "const char *const oid_name_table[OID__NR + 1] = {\n";

#for (my $i = 0; $i <= $#names; $i++) {

print C_FILE "\t"", $names[$i], "",\n"

#} #print C_FILE "\t"Unknown-OID"\n"; #print C_FILE "};\n";

Polish off

close C_FILE or die;