xref: /openbmc/linux/lib/build_OID_registry (revision aaa880f8) 
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;
11use Cwd qw(abs_path);
12
13my @names = ();
14my @oids = ();
15
16if ($#ARGV != 1) {
17    print STDERR "Format: ", $0, " <in-h-file> <out-c-file>\n";
18    exit(2);
19}
20
21my $abs_srctree = abs_path($ENV{'srctree'});
22
23#
24# Open the file to read from
25#
26open IN_FILE, "<$ARGV[0]" || die;
27while (<IN_FILE>) {
28    chomp;
29    if (m!\s+OID_([a-zA-z][a-zA-Z0-9_]+),\s+/[*]\s+([012][.0-9]*)\s+[*]/!) {
30	push @names, $1;
31	push @oids, $2;
32    }
33}
34close IN_FILE || die;
35
36#
37# Open the files to write into
38#
39open C_FILE, ">$ARGV[1]" or die;
40print C_FILE "/*\n";
41my $scriptname = $0;
42$scriptname =~ s#^\Q$abs_srctree/\E##;
43print C_FILE " * Automatically generated by ", $scriptname, ".  Do not edit\n";
44print C_FILE " */\n";
45
46#
47# Split the data up into separate lists and also determine the lengths of the
48# encoded data arrays.
49#
50my @indices = ();
51my @lengths = ();
52my $total_length = 0;
53
54for (my $i = 0; $i <= $#names; $i++) {
55    my $name = $names[$i];
56    my $oid = $oids[$i];
57
58    my @components = split(/[.]/, $oid);
59
60    # Determine the encoded length of this OID
61    my $size = $#components;
62    for (my $loop = 2; $loop <= $#components; $loop++) {
63	my $c = $components[$loop];
64
65	# We will base128 encode the number
66	my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
67	$tmp = int($tmp / 7);
68	$size += $tmp;
69    }
70    push @lengths, $size;
71    push @indices, $total_length;
72    $total_length += $size;
73}
74
75#
76# Emit the look-up-by-OID index table
77#
78print C_FILE "\n";
79if ($total_length <= 255) {
80    print C_FILE "static const unsigned char oid_index[OID__NR + 1] = {\n";
81} else {
82    print C_FILE "static const unsigned short oid_index[OID__NR + 1] = {\n";
83}
84for (my $i = 0; $i <= $#names; $i++) {
85    print C_FILE "\t[OID_", $names[$i], "] = ", $indices[$i], ",\n"
86}
87print C_FILE "\t[OID__NR] = ", $total_length, "\n";
88print C_FILE "};\n";
89
90#
91# Encode the OIDs
92#
93my @encoded_oids = ();
94
95for (my $i = 0; $i <= $#names; $i++) {
96    my @octets = ();
97
98    my @components = split(/[.]/, $oids[$i]);
99
100    push @octets, $components[0] * 40 + $components[1];
101
102    for (my $loop = 2; $loop <= $#components; $loop++) {
103	my $c = $components[$loop];
104
105	# Base128 encode the number
106	my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
107	$tmp = int($tmp / 7);
108
109	for (; $tmp > 0; $tmp--) {
110	    push @octets, (($c >> $tmp * 7) & 0x7f) | 0x80;
111	}
112	push @octets, $c & 0x7f;
113    }
114
115    push @encoded_oids, \@octets;
116}
117
118#
119# Create a hash value for each OID
120#
121my @hash_values = ();
122for (my $i = 0; $i <= $#names; $i++) {
123    my @octets = @{$encoded_oids[$i]};
124
125    my $hash = $#octets;
126    foreach (@octets) {
127	$hash += $_ * 33;
128    }
129
130    $hash = ($hash >> 24) ^ ($hash >> 16) ^ ($hash >> 8) ^ ($hash);
131
132    push @hash_values, $hash & 0xff;
133}
134
135#
136# Emit the OID data
137#
138print C_FILE "\n";
139print C_FILE "static const unsigned char oid_data[", $total_length, "] = {\n";
140for (my $i = 0; $i <= $#names; $i++) {
141    my @octets = @{$encoded_oids[$i]};
142    print C_FILE "\t";
143    print C_FILE $_, ", " foreach (@octets);
144    print C_FILE "\t// ", $names[$i];
145    print C_FILE "\n";
146}
147print C_FILE "};\n";
148
149#
150# Build the search index table (ordered by length then hash then content)
151#
152my @index_table = ( 0 .. $#names );
153
154@index_table = sort {
155    my @octets_a = @{$encoded_oids[$a]};
156    my @octets_b = @{$encoded_oids[$b]};
157
158    return $hash_values[$a] <=> $hash_values[$b]
159	if ($hash_values[$a] != $hash_values[$b]);
160    return $#octets_a <=> $#octets_b
161	if ($#octets_a != $#octets_b);
162    for (my $i = $#octets_a; $i >= 0; $i--) {
163	return $octets_a[$i] <=> $octets_b[$i]
164	    if ($octets_a[$i] != $octets_b[$i]);
165    }
166    return 0;
167
168} @index_table;
169
170#
171# Emit the search index and hash value table
172#
173print C_FILE "\n";
174print C_FILE "static const struct {\n";
175print C_FILE "\tunsigned char hash;\n";
176if ($#names <= 255) {
177    print C_FILE "\tenum OID oid : 8;\n";
178} else {
179    print C_FILE "\tenum OID oid : 16;\n";
180}
181print C_FILE "} oid_search_table[OID__NR] = {\n";
182for (my $i = 0; $i <= $#names; $i++) {
183    my @octets = @{$encoded_oids[$index_table[$i]]};
184    printf(C_FILE "\t[%3u] = { %3u, OID_%-35s }, // ",
185	   $i,
186	   $hash_values[$index_table[$i]],
187	   $names[$index_table[$i]]);
188    printf C_FILE "%02x", $_ foreach (@octets);
189    print C_FILE "\n";
190}
191print C_FILE "};\n";
192
193#
194# Emit the OID debugging name table
195#
196#print C_FILE "\n";
197#print C_FILE "const char *const oid_name_table[OID__NR + 1] = {\n";
198#
199#for (my $i = 0; $i <= $#names; $i++) {
200#    print C_FILE "\t\"", $names[$i], "\",\n"
201#}
202#print C_FILE "\t\"Unknown-OID\"\n";
203#print C_FILE "};\n";
204
205#
206# Polish off
207#
208close C_FILE or die;
209