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Linux/lib/build_OID_registry

  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 
 14 use strict;
 15 
 16 my @names = ();
 17 my @oids = ();
 18 
 19 if ($#ARGV != 1) {
 20     print STDERR "Format: ", $0, " <in-h-file> <out-c-file>\n";
 21     exit(2);
 22 }
 23 
 24 #
 25 # Open the file to read from
 26 #
 27 open IN_FILE, "<$ARGV[0]" || die;
 28 while (<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, $2;
 33     }
 34 }
 35 close IN_FILE || die;
 36 
 37 #
 38 # Open the files to write into
 39 #
 40 open C_FILE, ">$ARGV[1]" or die;
 41 print C_FILE "/*\n";
 42 print C_FILE " * Automatically generated by ", $0, ".  Do not edit\n";
 43 print 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 #
 49 my @indices = ();
 50 my @lengths = ();
 51 my $total_length = 0;
 52 
 53 for (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 += $size;
 72 }
 73 
 74 #
 75 # Emit the look-up-by-OID index table
 76 #
 77 print C_FILE "\n";
 78 if ($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 }
 83 for (my $i = 0; $i <= $#names; $i++) {
 84     print C_FILE "\t[OID_", $names[$i], "] = ", $indices[$i], ",\n"
 85 }
 86 print C_FILE "\t[OID__NR] = ", $total_length, "\n";
 87 print C_FILE "};\n";
 88 
 89 #
 90 # Encode the OIDs
 91 #
 92 my @encoded_oids = ();
 93 
 94 for (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 #
120 my @hash_values = ();
121 for (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 #
137 print C_FILE "\n";
138 print C_FILE "static const unsigned char oid_data[", $total_length, "] = {\n";
139 for (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 }
146 print C_FILE "};\n";
147 
148 #
149 # Build the search index table (ordered by length then hash then content)
150 #
151 my @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 #
172 print C_FILE "\n";
173 print C_FILE "static const struct {\n";
174 print C_FILE "\tunsigned char hash;\n";
175 if ($#names <= 255) {
176     print C_FILE "\tenum OID oid : 8;\n";
177 } else {
178     print C_FILE "\tenum OID oid : 16;\n";
179 }
180 print C_FILE "} oid_search_table[OID__NR] = {\n";
181 for (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 }
190 print 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 #
207 close C_FILE or die;

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