xref: /openbmc/linux/lib/build_OID_registry (revision 7c768f84) 
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