Encode::IMAPUTF7(3pm) User Contributed Perl Documentation Encode::IMAPUTF7(3pm)
NAME
Encode::IMAPUTF7 - modification of UTF-7 encoding for IMAP
SYNOPSIS
use Encode qw/encode decode/;
use Encode::IMAPUTF7;
print encode('IMAP-UTF-7', 'RA~Xpertoire');
print decode('IMAP-UTF-7', R&AOk-pertoire');
ABSTRACT
IMAP mailbox names are encoded in a modified UTF7 when names contains international characters outside of the printable ASCII range. The
modified UTF-7 encoding is defined in RFC2060 (section 5.1.3).
There is another CPAN module with same purpose, Unicode::IMAPUtf7. However, it works correctly only with strings, which encoded form does
not contain plus sign. For example, the Cyrillic string x{043f}x{0440}x{0435}x{0434}x{043b}x{043e}x{0433} is represented in UTF-7 as
+BD8EQAQ1BDQEOwQ+BDM- Note the second plus sign 4 characters before the end. Unicode::IMAPUtf7 encodes the above string as
+BD8EQAQ1BDQEOwQ&BDM- which is not valid modified UTF-7 (the ampersand and the plus are swapped). The problem is solved by the current
module, which is slightly modified Encode::Unicode::UTF7 and has nothing common with Unicode::IMAPUtf7.
RFC2060 - section 5.1.3 - Mailbox International Naming Convention
By convention, international mailbox names are specified using a modified version of the UTF-7 encoding described in [UTF-7]. The purpose
of these modifications is to correct the following problems with UTF-7:
1) UTF-7 uses the "+" character for shifting; this conflicts with
the common use of "+" in mailbox names, in particular USENET
newsgroup names.
2) UTF-7's encoding is BASE64 which uses the "/" character; this
conflicts with the use of "/" as a popular hierarchy delimiter.
3) UTF-7 prohibits the unencoded usage of ""; this conflicts with
the use of "" as a popular hierarchy delimiter.
4) UTF-7 prohibits the unencoded usage of "~"; this conflicts with
the use of "~" in some servers as a home directory indicator.
5) UTF-7 permits multiple alternate forms to represent the same
string; in particular, printable US-ASCII chararacters can be
represented in encoded form.
In modified UTF-7, printable US-ASCII characters except for "&" represent themselves; that is, characters with octet values 0x20-0x25 and
0x27-0x7e. The character "&" (0x26) is represented by the two- octet sequence "&-".
All other characters (octet values 0x00-0x1f, 0x7f-0xff, and all Unicode 16-bit octets) are represented in modified BASE64, with a further
modification from [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be used to represent any printing US-ASCII character
which can represent itself.
"&" is used to shift to modified BASE64 and "-" to shift back to US- ASCII. All names start in US-ASCII, and MUST end in US-ASCII (that
is, a name that ends with a Unicode 16-bit octet MUST end with a "- ").
For example, here is a mailbox name which mixes English, Japanese, and Chinese text: ~peter/mail/&ZeVnLIqe-/&U,BTFw-
REQUESTS &; BUGS
Please report any requests, suggestions or bugs via the RT bug-tracking system at http://rt.cpan.org/ or email to
bug-Encode-IMAPUTF7@rt.cpan.org.
http://rt.cpan.org/NoAuth/Bugs.html?Dist=Encode-IMAPUTF7 is the RT queue for Encode::IMAPUTF7. Please check to see if your bug has already
been reported.
COPYRIGHT
Copyright 2005 Sava Chankov
Sava Chankov, sava@cpan.org
This software may be freely copied and distributed under the same terms and conditions as Perl.
AUTHORS
Peter Makholm <peter@makholm.net>, current maintainer
Sava Chankov <sava@cpan.org>, original author
SEE ALSO
perl(1), Encode.
perl v5.12.4 2011-09-25 Encode::IMAPUTF7(3pm)