diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/.gitignore | 2 | ||||
| -rw-r--r-- | lib/Kconfig | 5 | ||||
| -rw-r--r-- | lib/Makefile | 16 | ||||
| -rwxr-xr-x | lib/build_OID_registry | 209 | ||||
| -rw-r--r-- | lib/oid_registry.c | 89 |
5 files changed, 320 insertions, 1 deletions
diff --git a/lib/.gitignore b/lib/.gitignore index 3bef1ea94c99..09aae85418ab 100644 --- a/lib/.gitignore +++ b/lib/.gitignore @@ -3,4 +3,4 @@ # gen_crc32table crc32table.h - +oid_registry_data.c diff --git a/lib/Kconfig b/lib/Kconfig index bb94c1ba616a..4b31a46fb307 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -396,4 +396,9 @@ config SIGNATURE config LIBFDT bool +config OID_REGISTRY + tristate + help + Enable fast lookup object identifier registry. + endmenu diff --git a/lib/Makefile b/lib/Makefile index 42d283edc4d3..b0428960939f 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -150,3 +150,19 @@ quiet_cmd_crc32 = GEN $@ $(obj)/crc32table.h: $(obj)/gen_crc32table $(call cmd,crc32) + +# +# Build a fast OID lookip registry from include/linux/oid_registry.h +# +obj-$(CONFIG_OID_REGISTRY) += oid_registry.o + +$(obj)/oid_registry.c: $(obj)/oid_registry_data.c + +$(obj)/oid_registry_data.c: $(srctree)/include/linux/oid_registry.h \ + $(src)/build_OID_registry + $(call cmd,build_OID_registry) + +quiet_cmd_build_OID_registry = GEN $@ + cmd_build_OID_registry = perl $(srctree)/$(src)/build_OID_registry $< $@ + +clean-files += oid_registry_data.c diff --git a/lib/build_OID_registry b/lib/build_OID_registry new file mode 100755 index 000000000000..dfbdaab81bc8 --- /dev/null +++ b/lib/build_OID_registry @@ -0,0 +1,209 @@ +#!/usr/bin/perl -w +# +# Build a static ASN.1 Object Identified (OID) registry +# +# Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. +# Written by David Howells (dhowells@redhat.com) +# +# This program is free software; you can redistribute it and/or +# modify it under the terms of the GNU General Public Licence +# as published by the Free Software Foundation; either version +# 2 of the Licence, or (at your option) any later version. +# + +use strict; + +my @names = (); +my @oids = (); + +if ($#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; diff --git a/lib/oid_registry.c b/lib/oid_registry.c new file mode 100644 index 000000000000..33cfd171f627 --- /dev/null +++ b/lib/oid_registry.c @@ -0,0 +1,89 @@ +/* ASN.1 Object identifier (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. + */ + +#include <linux/export.h> +#include <linux/oid_registry.h> +#include "oid_registry_data.c" + +/** + * look_up_OID - Find an OID registration for the specified data + * @data: Binary representation of the OID + * @datasize: Size of the binary representation + */ +enum OID look_up_OID(const void *data, size_t datasize) +{ + const unsigned char *octets = data; + enum OID oid; + unsigned char xhash; + unsigned i, j, k, hash; + size_t len; + + /* Hash the OID data */ + hash = datasize - 1; + + for (i = 0; i < datasize; i++) + hash += octets[i] * 33; + hash = (hash >> 24) ^ (hash >> 16) ^ (hash >> 8) ^ hash; + hash &= 0xff; + + /* Binary search the OID registry. OIDs are stored in ascending order + * of hash value then ascending order of size and then in ascending + * order of reverse value. + */ + i = 0; + k = OID__NR; + while (i < k) { + j = (i + k) / 2; + + xhash = oid_search_table[j].hash; + if (xhash > hash) { + k = j; + continue; + } + if (xhash < hash) { + i = j + 1; + continue; + } + + oid = oid_search_table[j].oid; + len = oid_index[oid + 1] - oid_index[oid]; + if (len > datasize) { + k = j; + continue; + } + if (len < datasize) { + i = j + 1; + continue; + } + + /* Variation is most likely to be at the tail end of the + * OID, so do the comparison in reverse. + */ + while (len > 0) { + unsigned char a = oid_data[oid_index[oid] + --len]; + unsigned char b = octets[len]; + if (a > b) { + k = j; + goto next; + } + if (a < b) { + i = j + 1; + goto next; + } + } + return oid; + next: + ; + } + + return OID__NR; +} +EXPORT_SYMBOL_GPL(look_up_OID); |