| 1 |
=head1 NAME |
| 2 |
|
| 3 |
Net::FCP::Util - utility functions. |
| 4 |
|
| 5 |
=head1 SYNOPSIS |
| 6 |
|
| 7 |
use Net::FCP::Util; |
| 8 |
|
| 9 |
|
| 10 |
=head1 DESCRIPTION |
| 11 |
|
| 12 |
=over 4 |
| 13 |
|
| 14 |
=cut |
| 15 |
|
| 16 |
package Net::FCP::Util; |
| 17 |
|
| 18 |
use Carp (); |
| 19 |
use Digest::SHA1; |
| 20 |
use MIME::Base64 (); |
| 21 |
|
| 22 |
no warnings; |
| 23 |
|
| 24 |
use base Exporter::; |
| 25 |
|
| 26 |
@EXPORT_OK = qw(tolc touc xeh); |
| 27 |
|
| 28 |
=item touc $string |
| 29 |
|
| 30 |
Returns the uppercased version of the given identifier. Used internally to |
| 31 |
map from e.g. URIError/KeyCollision to the form used in this module, i.e. |
| 32 |
uri_error/key_collision etc. |
| 33 |
|
| 34 |
=cut |
| 35 |
|
| 36 |
sub touc($) { |
| 37 |
local $_ = shift; |
| 38 |
1 while s/((?:^|_)(?:svk|chk|uri)(?:_|$))/\U$1/; |
| 39 |
s/(?:^|_)(.)/\U$1/g; |
| 40 |
$_; |
| 41 |
} |
| 42 |
|
| 43 |
=item tolc $string |
| 44 |
|
| 45 |
Returns the lowercased version of the given identifier. See C<touc>. |
| 46 |
|
| 47 |
=cut |
| 48 |
|
| 49 |
sub tolc($) { |
| 50 |
local $_ = shift; |
| 51 |
1 while s/(SVK|CHK|URI)([^_])/$1\_$2/i; |
| 52 |
1 while s/([^_])(SVK|CHK|URI)/$1\_$2/i; |
| 53 |
s/(?<=[a-z])(?=[A-Z])/_/g; |
| 54 |
lc $_; |
| 55 |
} |
| 56 |
|
| 57 |
=item xeh $number |
| 58 |
|
| 59 |
The opposite of C<hex>, i.e. returns the the number as hex string. Mainly |
| 60 |
useful due to it's prototype of C<$>. |
| 61 |
|
| 62 |
=cut |
| 63 |
|
| 64 |
sub xeh($) { |
| 65 |
sprintf "%x", $_[0]; |
| 66 |
} |
| 67 |
|
| 68 |
=item log2 $num[, $minlog] |
| 69 |
|
| 70 |
Calculate the (integer) log2 of a number, rounded up. If C<$minlog> is |
| 71 |
given it will be the minimum value returned. |
| 72 |
|
| 73 |
=cut |
| 74 |
|
| 75 |
sub log2($;$) { # n, minlog |
| 76 |
$_[0] && length sprintf "%$_[1]b", $_[0] - 1; |
| 77 |
} |
| 78 |
# the above line is much faster than the equivalent |
| 79 |
# below, which illustrates a fine point of perl... |
| 80 |
# my ($n, $b) = @_; |
| 81 |
# $b++ while 1 << $b < $n; |
| 82 |
# $b; |
| 83 |
|
| 84 |
=item encode_mpi $num |
| 85 |
|
| 86 |
Encode the given number as a multiple-precision number (2 byte bitlength + bytes) |
| 87 |
|
| 88 |
=cut |
| 89 |
|
| 90 |
sub encode_mpi($) { |
| 91 |
my $num = pack "N", $_[0]; |
| 92 |
my $len = log2 $_[0], 1; |
| 93 |
$num =~ s/^\x00+//; |
| 94 |
pack "n a*", $len, $num; |
| 95 |
} |
| 96 |
|
| 97 |
=item decode_base64 $string |
| 98 |
|
| 99 |
Decode freenet's perverted version of base64. |
| 100 |
|
| 101 |
=cut |
| 102 |
|
| 103 |
sub decode_base64($) { |
| 104 |
my $s = shift; |
| 105 |
|
| 106 |
$s =~ y%~\-%+/%; |
| 107 |
MIME::Base64::decode_base64 "$s======"; |
| 108 |
} |
| 109 |
|
| 110 |
=item encode_base64 $data |
| 111 |
|
| 112 |
Encode into freenet's perverted version of base64. |
| 113 |
|
| 114 |
=cut |
| 115 |
|
| 116 |
sub encode_base64($) { |
| 117 |
my $s = MIME::Base64::encode_base64 shift, ""; |
| 118 |
$s =~ s/=+$//; |
| 119 |
$s =~ y%+/%~\-%; |
| 120 |
$s; |
| 121 |
} |
| 122 |
|
| 123 |
=item generate_chk_hash $metadata, $data |
| 124 |
|
| 125 |
Generate and return they hash portion (the part after the comma, the |
| 126 |
crypto key) that would be used in the CHK (as binary). This can be used to |
| 127 |
verify contents of a CHK, since this key is a hash over the data. |
| 128 |
|
| 129 |
(This function assumes a 128 bit key, which seems standard in freenet). |
| 130 |
|
| 131 |
=cut |
| 132 |
|
| 133 |
sub generate_chk_hash($$) { |
| 134 |
my $d = new Digest::SHA1; |
| 135 |
|
| 136 |
$d->add ($_[0]); |
| 137 |
$d->add ($_[1]); |
| 138 |
$d = $d->digest; |
| 139 |
|
| 140 |
my $k = new Digest::SHA1; |
| 141 |
$k->add ("\x00" x 1); # only one iteration |
| 142 |
$k->add ($d); |
| 143 |
|
| 144 |
substr $k->digest, 0, 16; # extract leading 128 bit |
| 145 |
} |
| 146 |
|
| 147 |
=item extract_chk_hash $uri |
| 148 |
|
| 149 |
Extract the hash portion (the part after the comma, the crypto key) of a |
| 150 |
CHK (in binary). Useful to compare against the output of generate_chk_key. |
| 151 |
|
| 152 |
=cut |
| 153 |
|
| 154 |
sub extract_chk_hash($) { |
| 155 |
$_[0] =~ /CHK\@[a-zA-Z0-9~\-]{31},([a-zA-Z0-9~\-]{22})/ |
| 156 |
or Carp::croak "unable to parse CHK key from '$_[0]'"; |
| 157 |
|
| 158 |
decode_base64 $1; |
| 159 |
} |
| 160 |
|
| 161 |
=back |
| 162 |
|
| 163 |
=head1 SEE ALSO |
| 164 |
|
| 165 |
L<Net::FCP>. |
| 166 |
|
| 167 |
=head1 BUGS |
| 168 |
|
| 169 |
Not heavily tested. |
| 170 |
|
| 171 |
=head1 AUTHOR |
| 172 |
|
| 173 |
Marc Lehmann <schmorp@schmorp.de> |
| 174 |
http://home.schmorp.de/ |
| 175 |
|
| 176 |
=cut |
| 177 |
|
| 178 |
1; |
| 179 |
|
