linux/lib/build_OID_registry
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   1#!/usr/bin/perl -w
   2#
   3# Build a static ASN.1 Object Identified (OID) registry
   4#
   5# Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   6# Written by David Howells (dhowells@redhat.com)
   7#
   8# This program is free software; you can redistribute it and/or
   9# modify it under the terms of the GNU General Public Licence
  10# as published by the Free Software Foundation; either version
  11# 2 of the Licence, or (at your option) any later version.
  12#
  13
  14use strict;
  15
  16my @names = ();
  17my @oids = ();
  18
  19if ($#ARGV != 1) {
  20    print STDERR "Format: ", $0, " <in-h-file> <out-c-file>\n";
  21    exit(2);
  22}
  23
  24#
  25# Open the file to read from
  26#
  27open IN_FILE, "<$ARGV[0]" || die;
  28while (<IN_FILE>) {
  29    chomp;
  30    if (m!\s+OID_([a-zA-z][a-zA-Z0-9_]+),\s+/[*]\s+([012][.0-9]*)\s+[*]/!) {
  31        push @names, $1;
  32        push @oids, $2;
  33    }
  34}
  35close IN_FILE || die;
  36
  37#
  38# Open the files to write into
  39#
  40open C_FILE, ">$ARGV[1]" or die;
  41print C_FILE "/*\n";
  42print C_FILE " * Automatically generated by ", $0, ".  Do not edit\n";
  43print C_FILE " */\n";
  44
  45#
  46# Split the data up into separate lists and also determine the lengths of the
  47# encoded data arrays.
  48#
  49my @indices = ();
  50my @lengths = ();
  51my $total_length = 0;
  52
  53for (my $i = 0; $i <= $#names; $i++) {
  54    my $name = $names[$i];
  55    my $oid = $oids[$i];
  56
  57    my @components = split(/[.]/, $oid);
  58
  59    # Determine the encoded length of this OID
  60    my $size = $#components;
  61    for (my $loop = 2; $loop <= $#components; $loop++) {
  62        my $c = $components[$loop];
  63
  64        # We will base128 encode the number
  65        my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
  66        $tmp = int($tmp / 7);
  67        $size += $tmp;
  68    }
  69    push @lengths, $size;
  70    push @indices, $total_length;
  71    $total_length += $size;
  72}
  73
  74#
  75# Emit the look-up-by-OID index table
  76#
  77print C_FILE "\n";
  78if ($total_length <= 255) {
  79    print C_FILE "static const unsigned char oid_index[OID__NR + 1] = {\n";
  80} else {
  81    print C_FILE "static const unsigned short oid_index[OID__NR + 1] = {\n";
  82}
  83for (my $i = 0; $i <= $#names; $i++) {
  84    print C_FILE "\t[OID_", $names[$i], "] = ", $indices[$i], ",\n"
  85}
  86print C_FILE "\t[OID__NR] = ", $total_length, "\n";
  87print C_FILE "};\n";
  88
  89#
  90# Encode the OIDs
  91#
  92my @encoded_oids = ();
  93
  94for (my $i = 0; $i <= $#names; $i++) {
  95    my @octets = ();
  96
  97    my @components = split(/[.]/, $oids[$i]);
  98
  99    push @octets, $components[0] * 40 + $components[1];
 100
 101    for (my $loop = 2; $loop <= $#components; $loop++) {
 102        my $c = $components[$loop];
 103
 104        # Base128 encode the number
 105        my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
 106        $tmp = int($tmp / 7);
 107
 108        for (; $tmp > 0; $tmp--) {
 109            push @octets, (($c >> $tmp * 7) & 0x7f) | 0x80;
 110        }
 111        push @octets, $c & 0x7f;
 112    }
 113
 114    push @encoded_oids, \@octets;
 115}
 116
 117#
 118# Create a hash value for each OID
 119#
 120my @hash_values = ();
 121for (my $i = 0; $i <= $#names; $i++) {
 122    my @octets = @{$encoded_oids[$i]};
 123
 124    my $hash = $#octets;
 125    foreach (@octets) {
 126        $hash += $_ * 33;
 127    }
 128
 129    $hash = ($hash >> 24) ^ ($hash >> 16) ^ ($hash >> 8) ^ ($hash);
 130
 131    push @hash_values, $hash & 0xff;
 132}
 133
 134#
 135# Emit the OID data
 136#
 137print C_FILE "\n";
 138print C_FILE "static const unsigned char oid_data[", $total_length, "] = {\n";
 139for (my $i = 0; $i <= $#names; $i++) {
 140    my @octets = @{$encoded_oids[$i]};
 141    print C_FILE "\t";
 142    print C_FILE $_, ", " foreach (@octets);
 143    print C_FILE "\t// ", $names[$i];
 144    print C_FILE "\n";
 145}
 146print C_FILE "};\n";
 147
 148#
 149# Build the search index table (ordered by length then hash then content)
 150#
 151my @index_table = ( 0 .. $#names );
 152
 153@index_table = sort {
 154    my @octets_a = @{$encoded_oids[$a]};
 155    my @octets_b = @{$encoded_oids[$b]};
 156
 157    return $hash_values[$a] <=> $hash_values[$b]
 158        if ($hash_values[$a] != $hash_values[$b]);
 159    return $#octets_a <=> $#octets_b
 160        if ($#octets_a != $#octets_b);
 161    for (my $i = $#octets_a; $i >= 0; $i--) {
 162        return $octets_a[$i] <=> $octets_b[$i]
 163            if ($octets_a[$i] != $octets_b[$i]);
 164    }
 165    return 0;
 166
 167} @index_table;
 168
 169#
 170# Emit the search index and hash value table
 171#
 172print C_FILE "\n";
 173print C_FILE "static const struct {\n";
 174print C_FILE "\tunsigned char hash;\n";
 175if ($#names <= 255) {
 176    print C_FILE "\tenum OID oid : 8;\n";
 177} else {
 178    print C_FILE "\tenum OID oid : 16;\n";
 179}
 180print C_FILE "} oid_search_table[OID__NR] = {\n";
 181for (my $i = 0; $i <= $#names; $i++) {
 182    my @octets = @{$encoded_oids[$index_table[$i]]};
 183    printf(C_FILE "\t[%3u] = { %3u, OID_%-35s }, // ",
 184           $i,
 185           $hash_values[$index_table[$i]],
 186           $names[$index_table[$i]]);
 187    printf C_FILE "%02x", $_ foreach (@octets);
 188    print C_FILE "\n";
 189}
 190print C_FILE "};\n";
 191
 192#
 193# Emit the OID debugging name table
 194#
 195#print C_FILE "\n";
 196#print C_FILE "const char *const oid_name_table[OID__NR + 1] = {\n";
 197#
 198#for (my $i = 0; $i <= $#names; $i++) {
 199#    print C_FILE "\t\"", $names[$i], "\",\n"
 200#}
 201#print C_FILE "\t\"Unknown-OID\"\n";
 202#print C_FILE "};\n";
 203
 204#
 205# Polish off
 206#
 207close C_FILE or die;
 208
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