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
  53print "Compiling ", $#names + 1, " OIDs\n";
  54
  55for (my $i = 0; $i <= $#names; $i++) {
  56    my $name = $names[$i];
  57    my $oid = $oids[$i];
  58
  59    my @components = split(/[.]/, $oid);
  60
  61    # Determine the encoded length of this OID
  62    my $size = $#components;
  63    for (my $loop = 2; $loop <= $#components; $loop++) {
  64        my $c = $components[$loop];
  65
  66        # We will base128 encode the number
  67        my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
  68        $tmp = int($tmp / 7);
  69        $size += $tmp;
  70    }
  71    push @lengths, $size;
  72    push @indices, $total_length;
  73    $total_length += $size;
  74}
  75
  76#
  77# Emit the look-up-by-OID index table
  78#
  79print C_FILE "\n";
  80if ($total_length <= 255) {
  81    print C_FILE "static const unsigned char oid_index[OID__NR + 1] = {\n";
  82} else {
  83    print C_FILE "static const unsigned short oid_index[OID__NR + 1] = {\n";
  84}
  85for (my $i = 0; $i <= $#names; $i++) {
  86    print C_FILE "\t[OID_", $names[$i], "] = ", $indices[$i], ",\n"
  87}
  88print C_FILE "\t[OID__NR] = ", $total_length, "\n";
  89print C_FILE "};\n";
  90
  91#
  92# Encode the OIDs
  93#
  94my @encoded_oids = ();
  95
  96for (my $i = 0; $i <= $#names; $i++) {
  97    my @octets = ();
  98
  99    my @components = split(/[.]/, $oids[$i]);
 100
 101    push @octets, $components[0] * 40 + $components[1];
 102
 103    for (my $loop = 2; $loop <= $#components; $loop++) {
 104        my $c = $components[$loop];
 105
 106        # Base128 encode the number
 107        my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
 108        $tmp = int($tmp / 7);
 109
 110        for (; $tmp > 0; $tmp--) {
 111            push @octets, (($c >> $tmp * 7) & 0x7f) | 0x80;
 112        }
 113        push @octets, $c & 0x7f;
 114    }
 115
 116    push @encoded_oids, \@octets;
 117}
 118
 119#
 120# Create a hash value for each OID
 121#
 122my @hash_values = ();
 123for (my $i = 0; $i <= $#names; $i++) {
 124    my @octets = @{$encoded_oids[$i]};
 125
 126    my $hash = $#octets;
 127    foreach (@octets) {
 128        $hash += $_ * 33;
 129    }
 130
 131    $hash = ($hash >> 24) ^ ($hash >> 16) ^ ($hash >> 8) ^ ($hash);
 132
 133    push @hash_values, $hash & 0xff;
 134}
 135
 136#
 137# Emit the OID data
 138#
 139print C_FILE "\n";
 140print C_FILE "static const unsigned char oid_data[", $total_length, "] = {\n";
 141for (my $i = 0; $i <= $#names; $i++) {
 142    my @octets = @{$encoded_oids[$i]};
 143    print C_FILE "\t";
 144    print C_FILE $_, ", " foreach (@octets);
 145    print C_FILE "\t// ", $names[$i];
 146    print C_FILE "\n";
 147}
 148print C_FILE "};\n";
 149
 150#
 151# Build the search index table (ordered by length then hash then content)
 152#
 153my @index_table = ( 0 .. $#names );
 154
 155@index_table = sort {
 156    my @octets_a = @{$encoded_oids[$a]};
 157    my @octets_b = @{$encoded_oids[$b]};
 158
 159    return $hash_values[$a] <=> $hash_values[$b]
 160        if ($hash_values[$a] != $hash_values[$b]);
 161    return $#octets_a <=> $#octets_b
 162        if ($#octets_a != $#octets_b);
 163    for (my $i = $#octets_a; $i >= 0; $i--) {
 164        return $octets_a[$i] <=> $octets_b[$i]
 165            if ($octets_a[$i] != $octets_b[$i]);
 166    }
 167    return 0;
 168
 169} @index_table;
 170
 171#
 172# Emit the search index and hash value table
 173#
 174print C_FILE "\n";
 175print C_FILE "static const struct {\n";
 176print C_FILE "\tunsigned char hash;\n";
 177if ($#names <= 255) {
 178    print C_FILE "\tenum OID oid : 8;\n";
 179} else {
 180    print C_FILE "\tenum OID oid : 16;\n";
 181}
 182print C_FILE "} oid_search_table[OID__NR] = {\n";
 183for (my $i = 0; $i <= $#names; $i++) {
 184    my @octets = @{$encoded_oids[$index_table[$i]]};
 185    printf(C_FILE "\t[%3u] = { %3u, OID_%-35s }, // ",
 186           $i,
 187           $hash_values[$index_table[$i]],
 188           $names[$index_table[$i]]);
 189    printf C_FILE "%02x", $_ foreach (@octets);
 190    print C_FILE "\n";
 191}
 192print C_FILE "};\n";
 193
 194#
 195# Emit the OID debugging name table
 196#
 197#print C_FILE "\n";
 198#print C_FILE "const char *const oid_name_table[OID__NR + 1] = {\n";
 199#
 200#for (my $i = 0; $i <= $#names; $i++) {
 201#    print C_FILE "\t\"", $names[$i], "\",\n"
 202#}
 203#print C_FILE "\t\"Unknown-OID\"\n";
 204#print C_FILE "};\n";
 205
 206#
 207# Polish off
 208#
 209close C_FILE or die;
 210
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