seems common in practice to block addresses having "%!/|`#&?" in the
local part. The idea is to restrict ourselves to basic ASCII
alphanumerics, plus a small set of printable ASCII, namely "=_+-~.".
-Spaces are replaced with "_", the characters "A-Za-z0-9.\+\-~" encode
-as themselves, and everything else is written "=USTR=" where USTR is
-the base64 (using "A-Za-z0-9\+\-\." as digits) encoding of the unicode
-character code.
+Spaces are replaced with "+", "/" with "~", the characters
+"A-Za-z0-9_.-" encode as themselves, and everything else is written
+"=USTR=" where USTR is the base64 (using "A-Za-z0-9_." as digits)
+encoding of the unicode character code.
The characters '+' and '-' are pretty widely used to attach suffixes
(although usually only one works on a given mail host). It seems ok to
=cut
-our $digit_string="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-.";
+our $digit_string="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_.";
+
+our $must_base64=qr{[^a-zA-Z0-9\.\-\/_ ]};
+our $digit_rex=qr{[$digit_string]+};
+our $valid_rex=qr{[A-Za-z0-9.\=\_\~]+};
+
our @digits=split "",$digit_string;
sub encode_num($){
$num=$num << 6;
$num+=$remainder;
- print STDERR "num=$num\n";
shift @chars;
}
}
sub encode_ytext($){
my $str=shift;
- # "=" we use as an escape, and '_' for space
- $str=~ s/([^a-zA-Z0-9+\-~. ])/"=".encode_num(ord($1))."="/ge;
- $str=~ s/ /_/g;
+ # "=" we use as an escape, and '+' for space
+ $str=~ s/($must_base64)/"=".encode_num(ord($1))."="/ge;
+
+ $str=~ s|/|~|g;
+ $str=~ s/ /+/g;
+
return $str;
};
sub decode_ytext($){
my $str = shift;
- $str=~ s/=([a-zA-Z0-9+\-\.])+=/ decode_str($1)/eg;
- $str=~ s/_/ /g;
-
+
+ $str=~ s/\+/ /g;
+ $str=~ s|~|/|g;
+ $str=~ s/=($digit_rex)+=/ decode_str($1)/eg;
return $str;
}