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[backend] add more ASN1 helpers for packing and unpacking
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- asn1_enumerated, asn1_string, asn1_bytes, asn1_bits_list
- asn1_unpack_integer, asn1_unpack_set, asn1_unpack_bytes, asn1_unpack_octet_string,
  asn1_unpack_string, asn1_unpack_bits_list, asn1_unpack_boolean, asn1_unpack_tagged
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@mlschroe @coolo
mlschroe authored and coolo committed Nov 14, 2018
1 parent b71d859 commit ddbf526
Showing 1 changed file with 121 additions and 25 deletions.
146 changes: 121 additions & 25 deletions src/backend/BSASN1.pm
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@

package BSASN1;

use Encode;
use MIME::Base64 ();

use strict;
Expand All @@ -44,9 +45,13 @@ our $ENUMERATED = 0x0a;
our $UTF8STRING = 0x0c;
our $SEQUENCE = 0x10;
our $SET = 0x11;
our $NUMERICSTRING = 0x12;
our $PRINTABLESTRING = 0x13;
our $IA5STRING = 0x16;
our $UTCTIME = 0x17;
our $GENTIME = 0x18;
our $UNIVERSALSTRING = 0x1c;
our $BMPSTRING = 0x1e;

sub utctime {
my ($t) = @_;
Expand All @@ -60,6 +65,22 @@ sub gentime {
return sprintf "%04d%02d%02d%02d%02d%02dZ", $gt[5] + 1900, $gt[4] + 1, @gt[3,2,1,0];
}

sub der2pem {
my ($in, $what) = @_;
my $ret = MIME::Base64::encode_base64($in, '');
$ret =~ s/(.{64})/$1\n/g;
$ret =~ s/\n$//s;
return "-----BEGIN $what-----\n$ret\n-----END $what-----\n";
}

sub pem2der {
my ($in, $what) = @_;
return undef unless $in =~ s/^.*?-----BEGIN \Q$what\E-----\n//s;
return undef unless $in =~ s/\n-----END \Q$what\E-----.*$//s;
return MIME::Base64::decode_base64($in);
}

# raw packing/unpacking helpers
sub asn1_pack {
my ($tag, @data) = @_;
my $data = join('', @data);
Expand All @@ -71,7 +92,7 @@ sub asn1_pack {

sub asn1_unpack {
my ($in, $allowed, $optional, $exact) = @_;
$allowed = [ $allowed ] if defined($allowed) && !ref($allowed);
$allowed = [ $allowed ] if $allowed && !ref($allowed);
if (length($in) < 2) {
return ($in, undef, '', '') if $optional || grep {!defined($_)} @{$allowed || []};
die("unexpected end of asn1 data\n");
Expand All @@ -95,21 +116,6 @@ sub asn1_unpack {
return (substr($in, $off + $l), $tag, substr($in, $off, $l), substr($in, 0, $off + $l));
}

sub der2pem {
my ($in, $what) = @_;
my $ret = MIME::Base64::encode_base64($in, '');
$ret =~ s/(.{64})/$1\n/g;
$ret =~ s/\n$//s;
return "-----BEGIN $what-----\n$ret\n-----END $what-----\n";
}

sub pem2der {
my ($in, $what) = @_;
return undef unless $in =~ s/^.*?-----BEGIN \Q$what\E-----\n//s;
return undef unless $in =~ s/\n-----END \Q$what\E-----.*$//s;
return MIME::Base64::decode_base64($in);
}

# little pack helpers
sub asn1_null {
return asn1_pack($NULL);
Expand All @@ -131,6 +137,11 @@ sub asn1_integer_mpi {
return asn1_pack($INTEGER, unpack('C', $mpi) >= 128 ? pack('C', 0).$mpi : $mpi);
}

sub asn1_enumerated {
return asn1_pack($ENUMERATED, pack('c', $_[0])) if $_[0] >= -128 && $_[0] <= 127;
return asn1_pack($ENUMERATED, substr(pack('N', $_[0]), 3 - (length(sprintf('%b', $_[0] >= 0 ? $_[0] : ~$_[0])) >> 3)));
}

sub asn1_obj_id {
my ($o1, $o2, @o) = @_;
return asn1_pack($OBJ_ID, pack('w*', $o1 * 40 + $o2, @o));
Expand All @@ -156,6 +167,16 @@ sub asn1_octet_string {
return asn1_pack($OCTET_STRING, $_[0]);
}

sub asn1_string {
my ($s, $tag) = @_;
Encode::_utf8_off($s); # hope for the best
return asn1_pack($tag || $UTF8STRING, $s);
}

sub asn1_bytes {
return asn1_pack($BIT_STRING, pack('C', 0).$_[0]);
}

sub asn1_tagged {
return asn1_pack(($_[0] < 0x40 ? $CONT : 0) | $CONS | $_[0], $_[1]);
}
Expand All @@ -165,40 +186,115 @@ sub asn1_tagged_implicit {
return asn1_pack(($_[0] < 0x40 ? $CONT : 0) | ($tag & $CONS) | $_[0], $body).$rest;
}

sub asn1_bits_list {
my $v = '';
vec($v, $_ ^ 7, 1) = 1 for @_;
my $maxbit = $v eq '' ? 7 : (sort {$b <=> $a} @_)[0];
return asn1_pack($BIT_STRING, pack('C', 7 - ($maxbit % 8)).$v);
}


# little unpack helpers (intag = 0 : any tag allowed)

sub asn1_gettag {
return (asn1_unpack(@_))[1];
}

sub asn1_unpack_body {
my ($in, $intag, $default) = @_;
return (asn1_unpack($in, defined($intag) ? $intag : $default, undef, 1))[2];
}

sub asn1_unpack_integer {
my $in = asn1_unpack_body($_[0], $_[1], $INTEGER);
return 0 if $in eq '';
return unpack('c', $in) if length($in) == 1;
my $n = pack('C', unpack('C', $in) >= 128 ? 255 : 0) x 4;
$n = unpack('N', substr("$n$in", -4));
return unpack('C', $in) >= 128 ? $n - 4294967296 : $n;
}

sub asn1_unpack_integer_mpi {
my ($in, $intag) = @_;
$intag = $INTEGER unless defined $intag;
(undef, undef, $in) = asn1_unpack($in, $intag ? $intag : undef, undef, 1);
my $in = asn1_unpack_body($_[0], $_[1], $INTEGER);
$in = substr($in, 1) while $in ne '' && unpack('C', $in) == 0;
return $in;
}

sub asn1_unpack_sequence {
my ($in, $intag, $allowed) = @_;
$intag = $CONS | $SEQUENCE unless defined $intag;
(undef, undef, $in) = asn1_unpack($in, $intag ? $intag : undef, undef, 1);
$in = asn1_unpack_body($in, $intag, $CONS | $SEQUENCE);
my @ret;
my $tagbody;
if ($allowed) {
if ($allowed && ref($allowed)) {
for my $all (@$allowed) {
return @ret, $in if $all && !ref($all) && $all == -1;
($in, undef, undef, $tagbody) = asn1_unpack($in, $all ? $all : undef);
return @ret, $in if $all && !ref($all) && $all == -1; # -1: get rest
($in, undef, undef, $tagbody) = asn1_unpack($in, $all);
push @ret, $tagbody;
}
die("tailing data at end of asn1 sequence\n") if $in ne '';
return @ret;
}
while ($in ne '') {
($in, undef, undef, $tagbody) = asn1_unpack($in);
($in, undef, undef, $tagbody) = asn1_unpack($in, $allowed);
push @ret, $tagbody;
}
return @ret;
}

sub asn1_unpack_set {
my ($in, $intag, $allowed) = @_;
my $in = asn1_unpack_body($in, $intag, $CONS | $SET);
my @ret;
my $tagbody;
while ($in ne '') {
($in, undef, undef, $tagbody) = asn1_unpack($in, $allowed);
push @ret, $tagbody;
}
return @ret;
}

sub asn1_unpack_bytes {
my $in = asn1_unpack_body($_[0], $_[1], $BIT_STRING);
die("unpack_bytes: bit number not multiple of 8\n") unless unpack('C', $in) == 0;
return substr($in, 1);
}

sub asn1_unpack_octet_string {
return asn1_unpack_body($_[0], $_[1], $OCTET_STRING);
}

sub asn1_unpack_string {
my ($in, $intag) = @_;
$intag = [ $UTF8STRING, $NUMERICSTRING, $PRINTABLESTRING, $IA5STRING, $BMPSTRING, $UNIVERSALSTRING ] unless defined $intag;
my (undef, $tag, $in) = asn1_unpack($in, $intag, undef, 1);
if ($tag == $BMPSTRING) {
$in = Encode::decode('UCS-2BE', $in);
Encode::_utf8_off($in);
} elsif ($tag == $UNIVERSALSTRING) {
$in = Encode::decode('UCS-4BE', $in);
Encode::_utf8_off($in);
}
return $in;
}

sub asn1_unpack_bits_list {
my $in = asn1_unpack_body($_[0], $_[1], $BIT_STRING);
my $empty = unpack('C', $in);
die("unpack_bits: empty bits not in range 0..7\n") if $empty > 7;
$in = unpack('B*', substr($in, 1));
substr($in, -$empty, $empty, '') if $empty; # just in case
my @res;
substr($in, -1, 1, '') ne '0' && unshift(@res, length($in)) while $in ne '';
return @res;
}

sub asn1_unpack_boolean {
my $in = asn1_unpack_body($_[0], $_[1], $BOOLEAN);
return unpack('C', $in) ? 1 : 0;
}

sub asn1_unpack_tagged {
return asn1_unpack_body($_[0], $_[1], 0);
}

1;

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