xref: /openbmc/linux/lib/build_OID_registry (revision bef7a78d) 
1#!/usr/bin/perl -w
2# SPDX-License-Identifier: GPL-2.0-or-later
3#
4# Build a static ASN.1 Object Identified (OID) registry
5#
6# Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
7# Written by David Howells (dhowells@redhat.com)
8#
9
10use strict;
11
12my @names = ();
13my @oids = ();
14
15if ($#ARGV != 1) {
16    print STDERR "Format: ", $0, " <in-h-file> <out-c-file>\n";
17    exit(2);
18}
19
20#
21# Open the file to read from
22#
23open IN_FILE, "<$ARGV[0]" || die;
24while (<IN_FILE>) {
25    chomp;
26    if (m!\s+OID_([a-zA-z][a-zA-Z0-9_]+),\s+/[*]\s+([012][.0-9]*)\s+[*]/!) {
27	push @names, $1;
28	push @oids, $2;
29    }
30}
31close IN_FILE || die;
32
33#
34# Open the files to write into
35#
36open C_FILE, ">$ARGV[1]" or die;
37print C_FILE "/*\n";
38print C_FILE " * Automatically generated by ", $0, ".  Do not edit\n";
39print C_FILE " */\n";
40
41#
42# Split the data up into separate lists and also determine the lengths of the
43# encoded data arrays.
44#
45my @indices = ();
46my @lengths = ();
47my $total_length = 0;
48
49for (my $i = 0; $i <= $#names; $i++) {
50    my $name = $names[$i];
51    my $oid = $oids[$i];
52
53    my @components = split(/[.]/, $oid);
54
55    # Determine the encoded length of this OID
56    my $size = $#components;
57    for (my $loop = 2; $loop <= $#components; $loop++) {
58	my $c = $components[$loop];
59
60	# We will base128 encode the number
61	my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
62	$tmp = int($tmp / 7);
63	$size += $tmp;
64    }
65    push @lengths, $size;
66    push @indices, $total_length;
67    $total_length += $size;
68}
69
70#
71# Emit the look-up-by-OID index table
72#
73print C_FILE "\n";
74if ($total_length <= 255) {
75    print C_FILE "static const unsigned char oid_index[OID__NR + 1] = {\n";
76} else {
77    print C_FILE "static const unsigned short oid_index[OID__NR + 1] = {\n";
78}
79for (my $i = 0; $i <= $#names; $i++) {
80    print C_FILE "\t[OID_", $names[$i], "] = ", $indices[$i], ",\n"
81}
82print C_FILE "\t[OID__NR] = ", $total_length, "\n";
83print C_FILE "};\n";
84
85#
86# Encode the OIDs
87#
88my @encoded_oids = ();
89
90for (my $i = 0; $i <= $#names; $i++) {
91    my @octets = ();
92
93    my @components = split(/[.]/, $oids[$i]);
94
95    push @octets, $components[0] * 40 + $components[1];
96
97    for (my $loop = 2; $loop <= $#components; $loop++) {
98	my $c = $components[$loop];
99
100	# Base128 encode the number
101	my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
102	$tmp = int($tmp / 7);
103
104	for (; $tmp > 0; $tmp--) {
105	    push @octets, (($c >> $tmp * 7) & 0x7f) | 0x80;
106	}
107	push @octets, $c & 0x7f;
108    }
109
110    push @encoded_oids, \@octets;
111}
112
113#
114# Create a hash value for each OID
115#
116my @hash_values = ();
117for (my $i = 0; $i <= $#names; $i++) {
118    my @octets = @{$encoded_oids[$i]};
119
120    my $hash = $#octets;
121    foreach (@octets) {
122	$hash += $_ * 33;
123    }
124
125    $hash = ($hash >> 24) ^ ($hash >> 16) ^ ($hash >> 8) ^ ($hash);
126
127    push @hash_values, $hash & 0xff;
128}
129
130#
131# Emit the OID data
132#
133print C_FILE "\n";
134print C_FILE "static const unsigned char oid_data[", $total_length, "] = {\n";
135for (my $i = 0; $i <= $#names; $i++) {
136    my @octets = @{$encoded_oids[$i]};
137    print C_FILE "\t";
138    print C_FILE $_, ", " foreach (@octets);
139    print C_FILE "\t// ", $names[$i];
140    print C_FILE "\n";
141}
142print C_FILE "};\n";
143
144#
145# Build the search index table (ordered by length then hash then content)
146#
147my @index_table = ( 0 .. $#names );
148
149@index_table = sort {
150    my @octets_a = @{$encoded_oids[$a]};
151    my @octets_b = @{$encoded_oids[$b]};
152
153    return $hash_values[$a] <=> $hash_values[$b]
154	if ($hash_values[$a] != $hash_values[$b]);
155    return $#octets_a <=> $#octets_b
156	if ($#octets_a != $#octets_b);
157    for (my $i = $#octets_a; $i >= 0; $i--) {
158	return $octets_a[$i] <=> $octets_b[$i]
159	    if ($octets_a[$i] != $octets_b[$i]);
160    }
161    return 0;
162
163} @index_table;
164
165#
166# Emit the search index and hash value table
167#
168print C_FILE "\n";
169print C_FILE "static const struct {\n";
170print C_FILE "\tunsigned char hash;\n";
171if ($#names <= 255) {
172    print C_FILE "\tenum OID oid : 8;\n";
173} else {
174    print C_FILE "\tenum OID oid : 16;\n";
175}
176print C_FILE "} oid_search_table[OID__NR] = {\n";
177for (my $i = 0; $i <= $#names; $i++) {
178    my @octets = @{$encoded_oids[$index_table[$i]]};
179    printf(C_FILE "\t[%3u] = { %3u, OID_%-35s }, // ",
180	   $i,
181	   $hash_values[$index_table[$i]],
182	   $names[$index_table[$i]]);
183    printf C_FILE "%02x", $_ foreach (@octets);
184    print C_FILE "\n";
185}
186print C_FILE "};\n";
187
188#
189# Emit the OID debugging name table
190#
191#print C_FILE "\n";
192#print C_FILE "const char *const oid_name_table[OID__NR + 1] = {\n";
193#
194#for (my $i = 0; $i <= $#names; $i++) {
195#    print C_FILE "\t\"", $names[$i], "\",\n"
196#}
197#print C_FILE "\t\"Unknown-OID\"\n";
198#print C_FILE "};\n";
199
200#
201# Polish off
202#
203close C_FILE or die;
204