1#
2# $Id: Base64.pm,v 1.1.1.1 2003/08/02 23:39:56 takezoe Exp $
3
4package MIME::Base64;
5
6=head1 NAME
7
8MIME::Base64 - Encoding and decoding of base64 strings
9
10=head1 SYNOPSIS
11
12 use MIME::Base64;
13
14 $encoded = encode_base64('Aladdin:open sesame');
15 $decoded = decode_base64($encoded);
16
17=head1 DESCRIPTION
18
19This module provides functions to encode and decode strings into the
20Base64 encoding specified in RFC 2045 - I<MIME (Multipurpose Internet
21Mail Extensions)>. The Base64 encoding is designed to represent
22arbitrary sequences of octets in a form that need not be humanly
23readable. A 65-character subset ([A-Za-z0-9+/=]) of US-ASCII is used,
24enabling 6 bits to be represented per printable character.
25
26The following functions are provided:
27
28=over 4
29
30=item encode_base64($str)
31
32=item encode_base64($str, $eol);
33
34Encode data by calling the encode_base64() function.  The first
35argument is the string to encode.  The second argument is the line
36ending sequence to use (it is optional and defaults to C<"\n">).  The
37returned encoded string is broken into lines of no more than 76
38characters each and it will end with $eol unless it is empty.  Pass an
39empty string as second argument if you do not want the encoded string
40broken into lines.
41
42=item decode_base64($str)
43
44Decode a base64 string by calling the decode_base64() function.  This
45function takes a single argument which is the string to decode and
46returns the decoded data.
47
48Any character not part of the 65-character base64 subset set is
49silently ignored.  Characters occuring after a '=' padding character
50are never decoded.
51
52If the length of the string to decode (after ignoring
53non-base64 chars) is not a multiple of 4 or padding occurs too early,
54then a warning is generated if perl is running under C<-w>.
55
56=back
57
58If you prefer not to import these routines into your namespace you can
59call them as:
60
61    use MIME::Base64 ();
62    $encoded = MIME::Base64::encode($decoded);
63    $decoded = MIME::Base64::decode($encoded);
64
65=head1 DIAGNOSTICS
66
67The following warnings might be generated if perl is invoked with the
68C<-w> switch:
69
70=over 4
71
72=item Premature end of base64 data
73
74The number of characters to decode is not a multiple of 4.  Legal
75base64 data should be padded with one or two "=" characters to make
76its length a multiple of 4.  The decoded result will anyway be as if
77the padding was there.
78
79=item Premature padding of base64 data
80
81The '=' padding character occurs as the first or second character
82in a base64 quartet.
83
84=back
85
86=head1 EXAMPLES
87
88If you want to encode a large file, you should encode it in chunks
89that are a multiple of 57 bytes.  This ensures that the base64 lines
90line up and that you do not end up with padding in the middle. 57
91bytes of data fills one complete base64 line (76 == 57*4/3):
92
93   use MIME::Base64 qw(encode_base64);
94
95   open(FILE, "/var/log/wtmp") or die "$!";
96   while (read(FILE, $buf, 60*57)) {
97       print encode_base64($buf);
98   }
99
100or if you know you have enough memory
101
102   use MIME::Base64 qw(encode_base64);
103   local($/) = undef;  # slurp
104   print encode_base64(<STDIN>);
105
106The same approach as a command line:
107
108   perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file
109
110Decoding does not need slurp mode if all the lines contains a multiple
111of 4 base64 chars:
112
113   perl -MMIME::Base64 -ne 'print decode_base64($_)' <file
114
115=head1 COPYRIGHT
116
117Copyright 1995-1999, 2001-2003 Gisle Aas.
118
119This library is free software; you can redistribute it and/or
120modify it under the same terms as Perl itself.
121
122Distantly based on LWP::Base64 written by Martijn Koster
123<m.koster@nexor.co.uk> and Joerg Reichelt <j.reichelt@nexor.co.uk> and
124code posted to comp.lang.perl <3pd2lp$6gf@wsinti07.win.tue.nl> by Hans
125Mulder <hansm@wsinti07.win.tue.nl>
126
127The XS implementation use code from metamail.  Copyright 1991 Bell
128Communications Research, Inc. (Bellcore)
129
130=cut
131
132use strict;
133use vars qw(@ISA @EXPORT $VERSION $OLD_CODE);
134
135require Exporter;
136require DynaLoader;
137@ISA = qw(Exporter DynaLoader);
138@EXPORT = qw(encode_base64 decode_base64);
139
140$VERSION = '2.20';
141
142eval { bootstrap MIME::Base64 $VERSION; };
143if ($@) {
144    # can't bootstrap XS implementation, use perl implementation
145    *encode_base64 = \&old_encode_base64;
146    *decode_base64 = \&old_decode_base64;
147
148    $OLD_CODE = $@;
149    #warn $@ if $^W;
150}
151
152# Historically this module has been implemented as pure perl code.
153# The XS implementation runs about 20 times faster, but the Perl
154# code might be more portable, so it is still here.
155
156use integer;
157
158sub old_encode_base64 ($;$)
159{
160    my $eol = $_[1];
161    $eol = "\n" unless defined $eol;
162
163    my $res = pack("u", $_[0]);
164    # Remove first character of each line, remove newlines
165    $res =~ s/^.//mg;
166    $res =~ s/\n//g;
167
168    $res =~ tr|` -_|AA-Za-z0-9+/|;               # `# help emacs
169    # fix padding at the end
170    my $padding = (3 - length($_[0]) % 3) % 3;
171    $res =~ s/.{$padding}$/'=' x $padding/e if $padding;
172    # break encoded string into lines of no more than 76 characters each
173    if (length $eol) {
174	$res =~ s/(.{1,76})/$1$eol/g;
175    }
176    return $res;
177}
178
179
180sub old_decode_base64 ($)
181{
182    local($^W) = 0; # unpack("u",...) gives bogus warning in 5.00[123]
183
184    my $str = shift;
185    $str =~ tr|A-Za-z0-9+=/||cd;            # remove non-base64 chars
186    if (length($str) % 4) {
187	require Carp;
188	Carp::carp("Length of base64 data not a multiple of 4")
189    }
190    $str =~ s/=+$//;                        # remove padding
191    $str =~ tr|A-Za-z0-9+/| -_|;            # convert to uuencoded format
192    return "" unless length $str;
193
194    ## I guess this could be written as
195    #return unpack("u", join('', map( chr(32 + length($_)*3/4) . $_,
196    #			$str =~ /(.{1,60})/gs) ) );
197    ## but I do not like that...
198    my $uustr = '';
199    my ($i, $l);
200    $l = length($str) - 60;
201    for ($i = 0; $i <= $l; $i += 60) {
202	$uustr .= "M" . substr($str, $i, 60);
203    }
204    $str = substr($str, $i);
205    # and any leftover chars
206    if ($str ne "") {
207	$uustr .= chr(32 + length($str)*3/4) . $str;
208    }
209    return unpack ("u", $uustr);
210}
211
212# Set up aliases so that these functions also can be called as
213#
214#    MIME::Base64::encode();
215#    MIME::Base64::decode();
216
217*encode = \&encode_base64;
218*decode = \&decode_base64;
219
2201;
221