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1 | # |
2 | # $Id: Base64.pm,v 2.16 2001/02/24 06:28:10 gisle Exp $ |
3 | |
4 | package MIME::Base64; |
5 | |
6 | =head1 NAME |
7 | |
8 | MIME::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 | |
19 | This module provides functions to encode and decode strings into the |
20 | Base64 encoding specified in RFC 2045 - I<MIME (Multipurpose Internet |
21 | Mail Extensions)>. The Base64 encoding is designed to represent |
22 | arbitrary sequences of octets in a form that need not be humanly |
23 | readable. A 65-character subset ([A-Za-z0-9+/=]) of US-ASCII is used, |
24 | enabling 6 bits to be represented per printable character. |
25 | |
26 | The following functions are provided: |
27 | |
28 | =over 4 |
29 | |
30 | =item encode_base64($str, [$eol]) |
31 | |
32 | Encode data by calling the encode_base64() function. The first |
33 | argument is the string to encode. The second argument is the line |
34 | ending sequence to use (it is optional and defaults to C<"\n">). The |
35 | returned encoded string is broken into lines of no more than 76 |
36 | characters each and it will end with $eol unless it is empty. Pass an |
37 | empty string as second argument if you do not want the encoded string |
38 | broken into lines. |
39 | |
40 | =item decode_base64($str) |
41 | |
42 | Decode a base64 string by calling the decode_base64() function. This |
43 | function takes a single argument which is the string to decode and |
44 | returns the decoded data. |
45 | |
46 | Any character not part of the 65-character base64 subset set is |
47 | silently ignored. Characters occuring after a '=' padding character |
48 | are never decoded. |
49 | |
50 | If the length of the string to decode (after ignoring |
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51 | non-base64 chars) is not a multiple of 4 or padding occurs too early, |
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52 | then a warning is generated if perl is running under C<-w>. |
53 | |
54 | =back |
55 | |
56 | If you prefer not to import these routines into your namespace you can |
57 | call them as: |
58 | |
59 | use MIME::Base64 (); |
60 | $encoded = MIME::Base64::encode($decoded); |
61 | $decoded = MIME::Base64::decode($encoded); |
62 | |
63 | =head1 DIAGNOSTICS |
64 | |
65 | The following warnings might be generated if perl is invoked with the |
66 | C<-w> switch: |
67 | |
68 | =over 4 |
69 | |
70 | =item Premature end of base64 data |
71 | |
72 | The number of characters to decode is not a multiple of 4. Legal |
73 | base64 data should be padded with one or two "=" characters to make |
74 | its length a multiple of 4. The decoded result will anyway be as if |
75 | the padding was there. |
76 | |
77 | =item Premature padding of base64 data |
78 | |
79 | The '=' padding character occurs as the first or second character |
80 | in a base64 quartet. |
81 | |
82 | =back |
83 | |
84 | =head1 EXAMPLES |
85 | |
86 | If you want to encode a large file, you should encode it in chunks |
87 | that are a multiple of 57 bytes. This ensures that the base64 lines |
88 | line up and that you do not end up with padding in the middle. 57 |
89 | bytes of data fills one complete base64 line (76 == 57*4/3): |
90 | |
91 | use MIME::Base64 qw(encode_base64); |
92 | |
93 | open(FILE, "/var/log/wtmp") or die "$!"; |
94 | while (read(FILE, $buf, 60*57)) { |
95 | print encode_base64($buf); |
96 | } |
97 | |
98 | or if you know you have enough memory |
99 | |
100 | use MIME::Base64 qw(encode_base64); |
101 | local($/) = undef; # slurp |
102 | print encode_base64(<STDIN>); |
103 | |
104 | The same approach as a command line: |
105 | |
106 | perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file |
107 | |
108 | Decoding does not need slurp mode if all the lines contains a multiple |
109 | of 4 base64 chars: |
110 | |
111 | perl -MMIME::Base64 -ne 'print decode_base64($_)' <file |
112 | |
113 | =head1 COPYRIGHT |
114 | |
115 | Copyright 1995-1999, 2001 Gisle Aas. |
116 | |
117 | This library is free software; you can redistribute it and/or |
118 | modify it under the same terms as Perl itself. |
119 | |
120 | Distantly based on LWP::Base64 written by Martijn Koster |
121 | <m.koster@nexor.co.uk> and Joerg Reichelt <j.reichelt@nexor.co.uk> and |
122 | code posted to comp.lang.perl <3pd2lp$6gf@wsinti07.win.tue.nl> by Hans |
123 | Mulder <hansm@wsinti07.win.tue.nl> |
124 | |
125 | The XS implementation use code from metamail. Copyright 1991 Bell |
126 | Communications Research, Inc. (Bellcore) |
127 | |
128 | =cut |
129 | |
130 | use strict; |
131 | use vars qw(@ISA @EXPORT $VERSION $OLD_CODE); |
132 | |
133 | require Exporter; |
134 | require DynaLoader; |
135 | @ISA = qw(Exporter DynaLoader); |
136 | @EXPORT = qw(encode_base64 decode_base64); |
137 | |
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138 | $VERSION = '2.12'; |
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139 | |
140 | eval { bootstrap MIME::Base64 $VERSION; }; |
141 | if ($@) { |
142 | # can't bootstrap XS implementation, use perl implementation |
143 | *encode_base64 = \&old_encode_base64; |
144 | *decode_base64 = \&old_decode_base64; |
145 | |
146 | $OLD_CODE = $@; |
147 | #warn $@ if $^W; |
148 | } |
149 | |
150 | # Historically this module has been implemented as pure perl code. |
151 | # The XS implementation runs about 20 times faster, but the Perl |
152 | # code might be more portable, so it is still here. |
153 | |
154 | use integer; |
155 | |
156 | sub old_encode_base64 ($;$) |
157 | { |
158 | my $res = ""; |
159 | my $eol = $_[1]; |
160 | $eol = "\n" unless defined $eol; |
161 | pos($_[0]) = 0; # ensure start at the beginning |
162 | |
163 | $res = join '', map( pack('u',$_)=~ /^.(\S*)/, ($_[0]=~/(.{1,45})/gs)); |
164 | |
165 | $res =~ tr|` -_|AA-Za-z0-9+/|; # `# help emacs |
166 | # fix padding at the end |
167 | my $padding = (3 - length($_[0]) % 3) % 3; |
168 | $res =~ s/.{$padding}$/'=' x $padding/e if $padding; |
169 | # break encoded string into lines of no more than 76 characters each |
170 | if (length $eol) { |
171 | $res =~ s/(.{1,76})/$1$eol/g; |
172 | } |
173 | return $res; |
174 | } |
175 | |
176 | |
177 | sub old_decode_base64 ($) |
178 | { |
179 | local($^W) = 0; # unpack("u",...) gives bogus warning in 5.00[123] |
180 | |
181 | my $str = shift; |
182 | $str =~ tr|A-Za-z0-9+=/||cd; # remove non-base64 chars |
183 | if (length($str) % 4) { |
184 | require Carp; |
185 | Carp::carp("Length of base64 data not a multiple of 4") |
186 | } |
187 | $str =~ s/=+$//; # remove padding |
188 | $str =~ tr|A-Za-z0-9+/| -_|; # convert to uuencoded format |
189 | |
190 | return join'', map( unpack("u", chr(32 + length($_)*3/4) . $_), |
191 | $str =~ /(.{1,60})/gs); |
192 | } |
193 | |
194 | # Set up aliases so that these functions also can be called as |
195 | # |
196 | # MIME::Base64::encode(); |
197 | # MIME::Base64::decode(); |
198 | |
199 | *encode = \&encode_base64; |
200 | *decode = \&decode_base64; |
201 | |
202 | 1; |