FreeBSD/Linux Kernel Cross Reference
sys/lib/build_OID_registry

     #!/usr/bin/perl -w
     #
     # Build a static ASN.1 Object Identified (OID) registry
     #
     # Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
     # Written by David Howells (dhowells@redhat.com)
     #
     # This program is free software; you can redistribute it and/or
     # modify it under the terms of the GNU General Public Licence
    # as published by the Free Software Foundation; either version
    # 2 of the Licence, or (at your option) any later version.
    #
    
    use strict;
    
    my @names = ();
    my @oids = ();
    
    if ($#ARGV != 1) {
        print STDERR "Format: ", $0, " <in-h-file> <out-c-file>\n";
        exit(2);
    }
    
    #
    # Open the file to read from
    #
    open IN_FILE, "<$ARGV[0]" || die;
    while (<IN_FILE>) {
        chomp;
        if (m!\s+OID_([a-zA-z][a-zA-Z0-9_]+),\s+/[*]\s+([012][.0-9]*)\s+[*]/!) {
            push @names, $1;
            push @oids, $2;
        }
    }
    close IN_FILE || die;
    
    #
    # Open the files to write into
    #
    open C_FILE, ">$ARGV[1]" or die;
    print C_FILE "/*\n";
    print C_FILE " * Automatically generated by ", $0, ".  Do not edit\n";
    print C_FILE " */\n";
    
    #
    # Split the data up into separate lists and also determine the lengths of the
    # encoded data arrays.
    #
    my @indices = ();
    my @lengths = ();
    my $total_length = 0;
    
    print "Compiling ", $#names + 1, " OIDs\n";
    
    for (my $i = 0; $i <= $#names; $i++) {
        my $name = $names[$i];
        my $oid = $oids[$i];
    
        my @components = split(/[.]/, $oid);
    
        # Determine the encoded length of this OID
        my $size = $#components;
        for (my $loop = 2; $loop <= $#components; $loop++) {
            my $c = $components[$loop];
    
            # We will base128 encode the number
            my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
            $tmp = int($tmp / 7);
            $size += $tmp;
        }
        push @lengths, $size;
        push @indices, $total_length;
        $total_length += $size;
    }
    
    #
    # Emit the look-up-by-OID index table
    #
    print C_FILE "\n";
    if ($total_length <= 255) {
        print C_FILE "static const unsigned char oid_index[OID__NR + 1] = {\n";
    } else {
        print C_FILE "static const unsigned short oid_index[OID__NR + 1] = {\n";
    }
    for (my $i = 0; $i <= $#names; $i++) {
        print C_FILE "\t[OID_", $names[$i], "] = ", $indices[$i], ",\n"
    }
    print C_FILE "\t[OID__NR] = ", $total_length, "\n";
    print C_FILE "};\n";
    
    #
    # Encode the OIDs
    #
    my @encoded_oids = ();
    
    for (my $i = 0; $i <= $#names; $i++) {
        my @octets = ();
    
        my @components = split(/[.]/, $oids[$i]);
   
       push @octets, $components[0] * 40 + $components[1];
   
       for (my $loop = 2; $loop <= $#components; $loop++) {
           my $c = $components[$loop];
   
           # Base128 encode the number
           my $tmp = ($c == 0) ? 0 : int(log($c)/log(2));
           $tmp = int($tmp / 7);
   
           for (; $tmp > 0; $tmp--) {
               push @octets, (($c >> $tmp * 7) & 0x7f) | 0x80;
           }
           push @octets, $c & 0x7f;
       }
   
       push @encoded_oids, \@octets;
   }
   
   #
   # Create a hash value for each OID
   #
   my @hash_values = ();
   for (my $i = 0; $i <= $#names; $i++) {
       my @octets = @{$encoded_oids[$i]};
   
       my $hash = $#octets;
       foreach (@octets) {
           $hash += $_ * 33;
       }
   
       $hash = ($hash >> 24) ^ ($hash >> 16) ^ ($hash >> 8) ^ ($hash);
   
       push @hash_values, $hash & 0xff;
   }
   
   #
   # Emit the OID data
   #
   print C_FILE "\n";
   print C_FILE "static const unsigned char oid_data[", $total_length, "] = {\n";
   for (my $i = 0; $i <= $#names; $i++) {
       my @octets = @{$encoded_oids[$i]};
       print C_FILE "\t";
       print C_FILE $_, ", " foreach (@octets);
       print C_FILE "\t// ", $names[$i];
       print C_FILE "\n";
   }
   print C_FILE "};\n";
   
   #
   # Build the search index table (ordered by length then hash then content)
   #
   my @index_table = ( 0 .. $#names );
   
   @index_table = sort {
       my @octets_a = @{$encoded_oids[$a]};
       my @octets_b = @{$encoded_oids[$b]};
   
       return $hash_values[$a] <=> $hash_values[$b]
           if ($hash_values[$a] != $hash_values[$b]);
       return $#octets_a <=> $#octets_b
           if ($#octets_a != $#octets_b);
       for (my $i = $#octets_a; $i >= 0; $i--) {
           return $octets_a[$i] <=> $octets_b[$i]
               if ($octets_a[$i] != $octets_b[$i]);
       }
       return 0;
   
   } @index_table;
   
   #
   # Emit the search index and hash value table
   #
   print C_FILE "\n";
   print C_FILE "static const struct {\n";
   print C_FILE "\tunsigned char hash;\n";
   if ($#names <= 255) {
       print C_FILE "\tenum OID oid : 8;\n";
   } else {
       print C_FILE "\tenum OID oid : 16;\n";
   }
   print C_FILE "} oid_search_table[OID__NR] = {\n";
   for (my $i = 0; $i <= $#names; $i++) {
       my @octets = @{$encoded_oids[$index_table[$i]]};
       printf(C_FILE "\t[%3u] = { %3u, OID_%-35s }, // ",
              $i,
              $hash_values[$index_table[$i]],
              $names[$index_table[$i]]);
       printf C_FILE "%02x", $_ foreach (@octets);
       print C_FILE "\n";
   }
   print C_FILE "};\n";
   
   #
   # Emit the OID debugging name table
   #
   #print C_FILE "\n";
   #print C_FILE "const char *const oid_name_table[OID__NR + 1] = {\n";
   #
   #for (my $i = 0; $i <= $#names; $i++) {
   #    print C_FILE "\t\"", $names[$i], "\",\n"
   #}
   #print C_FILE "\t\"Unknown-OID\"\n";
   #print C_FILE "};\n";
   
   #
   # Polish off
   #
   close C_FILE or die;

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