1# 2# $Id: Base64.pm,v 2.16 2001/02/24 06:28:10 gisle 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($str, [$eol]) 31 32Encode data by calling the encode_base64() function. The first 33argument is the string to encode. The second argument is the line 34ending sequence to use (it is optional and defaults to C<"\n">). The 35returned encoded string is broken into lines of no more than 76 36characters each and it will end with $eol unless it is empty. Pass an 37empty string as second argument if you do not want the encoded string 38broken into lines. 39 40=item decode_base64($str) 41 42Decode a base64 string by calling the decode_base64() function. This 43function takes a single argument which is the string to decode and 44returns the decoded data. 45 46Any character not part of the 65-character base64 subset set is 47silently ignored. Characters occuring after a '=' padding character 48are never decoded. 49 50If the length of the string to decode (after ignoring 51non-base64 chars) is not a multiple of 4 or padding occurs too ealy, 52then a warning is generated if perl is running under C<-w>. 53 54=back 55 56If you prefer not to import these routines into your namespace you can 57call them as: 58 59 use MIME::Base64 (); 60 $encoded = MIME::Base64::encode($decoded); 61 $decoded = MIME::Base64::decode($encoded); 62 63=head1 DIAGNOSTICS 64 65The following warnings might be generated if perl is invoked with the 66C<-w> switch: 67 68=over 4 69 70=item Premature end of base64 data 71 72The number of characters to decode is not a multiple of 4. Legal 73base64 data should be padded with one or two "=" characters to make 74its length a multiple of 4. The decoded result will anyway be as if 75the padding was there. 76 77=item Premature padding of base64 data 78 79The '=' padding character occurs as the first or second character 80in a base64 quartet. 81 82=back 83 84=head1 EXAMPLES 85 86If you want to encode a large file, you should encode it in chunks 87that are a multiple of 57 bytes. This ensures that the base64 lines 88line up and that you do not end up with padding in the middle. 57 89bytes 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 98or if you know you have enough memory 99 100 use MIME::Base64 qw(encode_base64); 101 local($/) = undef; # slurp 102 print encode_base64(<STDIN>); 103 104The same approach as a command line: 105 106 perl -MMIME::Base64 -0777 -ne 'print encode_base64($_)' <file 107 108Decoding does not need slurp mode if all the lines contains a multiple 109of 4 base64 chars: 110 111 perl -MMIME::Base64 -ne 'print decode_base64($_)' <file 112 113=head1 COPYRIGHT 114 115Copyright 1995-1999, 2001 Gisle Aas. 116 117This library is free software; you can redistribute it and/or 118modify it under the same terms as Perl itself. 119 120Distantly based on LWP::Base64 written by Martijn Koster 121<m.koster@nexor.co.uk> and Joerg Reichelt <j.reichelt@nexor.co.uk> and 122code posted to comp.lang.perl <3pd2lp$6gf@wsinti07.win.tue.nl> by Hans 123Mulder <hansm@wsinti07.win.tue.nl> 124 125The XS implementation use code from metamail. Copyright 1991 Bell 126Communications Research, Inc. (Bellcore) 127 128=cut 129 130use strict; 131use vars qw(@ISA @EXPORT $VERSION $OLD_CODE); 132 133require Exporter; 134require DynaLoader; 135@ISA = qw(Exporter DynaLoader); 136@EXPORT = qw(encode_base64 decode_base64); 137 138$VERSION = '2.12'; 139 140eval { bootstrap MIME::Base64 $VERSION; }; 141if ($@) { 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 $^W; 148} 149 150# Historically this module has been implemented as pure perl code. 151# The XS implementation runs about 20 times faster, but the Perl 152# code might be more portable, so it is still here. 153 154use integer; 155 156sub old_encode_base64 ($;$) 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 $res; 174} 175 176 177sub old_decode_base64 ($) 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 2021; 203