manpagez: man pages & more
man Encode::MIME::Header(3)
Home | html | info | man
Encode::MIME::Header(3pm)




NAME

       Encode::MIME::Header -- MIME encoding for an unstructured email header


SYNOPSIS

           use Encode qw(encode decode);

           my $mime_str = encode("MIME-Header", "Sample:Text \N{U+263A}");
           # $mime_str is "=?UTF-8?B?U2FtcGxlOlRleHQg4pi6?="

           my $mime_q_str = encode("MIME-Q", "Sample:Text \N{U+263A}");
           # $mime_q_str is "=?UTF-8?Q?Sample=3AText_=E2=98=BA?="

           my $str = decode("MIME-Header",
               "=?ISO-8859-1?B?SWYgeW91IGNhbiByZWFkIHRoaXMgeW8=?=\r\n " .
               "=?ISO-8859-2?B?dSB1bmRlcnN0YW5kIHRoZSBleGFtcGxlLg==?="
           );
           # $str is "If you can read this you understand the example."

           use Encode qw(decode :fallbacks);
           use Encode::MIME::Header;
           local $Encode::MIME::Header::STRICT_DECODE = 1;
           my $strict_string = decode("MIME-Header", $mime_string, FB_CROAK);
           # use strict decoding and croak on errors


ABSTRACT

       This module implements RFC 2047 <https://tools.ietf.org/html/rfc2047>
       MIME encoding for an unstructured field body of the email header.  It
       can also be used for RFC 822 <https://tools.ietf.org/html/rfc822>
       'text' token.  However, it cannot be used directly for the whole header
       with the field name or for the structured header fields like From, To,
       Cc, Message-Id, etc...  There are 3 encoding names supported by this
       module: "MIME-Header", "MIME-B" and "MIME-Q".


DESCRIPTION

       Decode method takes an unstructured field body of the email header (or
       RFC 822 <https://tools.ietf.org/html/rfc822> 'text' token) as its input
       and decodes each MIME encoded-word from input string to a sequence of
       bytes according to RFC 2047 <https://tools.ietf.org/html/rfc2047> and
       RFC 2231 <https://tools.ietf.org/html/rfc2231>.  Subsequently, each
       sequence of bytes with the corresponding MIME charset is decoded with
       the Encode module and finally, one output string is returned.  Text
       parts of the input string which do not contain MIME encoded-word stay
       unmodified in the output string.  Folded newlines between two
       consecutive MIME encoded-words are discarded, others are preserved in
       the output string.  "MIME-B" can decode Base64 variant, "MIME-Q" can
       decode Quoted-Printable variant and "MIME-Header" can decode both of
       them.  If Encode module does not support particular MIME charset or
       chosen variant then an action based on CHECK flags is performed (by
       default, the MIME encoded-word is not decoded).

       Encode method takes a scalar string as its input and uses strict UTF-8
       encoder for encoding it to UTF-8 bytes.  Then a sequence of UTF-8 bytes
       is encoded into MIME encoded-words ("MIME-Header" and "MIME-B" use a
       Base64 variant while "MIME-Q" uses a Quoted-Printable variant) where
       each MIME encoded-word is limited to 75 characters.  MIME encoded-words
       are separated by "CRLF SPACE" and joined to one output string.  Output
       string is suitable for unstructured field body of the email header.

       Both encode and decode methods propagate CHECK flags when encoding and
       decoding the MIME charset.


BUGS

       Versions prior to 2.22 (part of Encode 2.83) have a malfunctioning
       decoder and encoder.  The MIME encoder infamously inserted additional
       spaces or discarded white spaces between consecutive MIME encoded-
       words, which led to invalid MIME headers produced by this module.  The
       MIME decoder had a tendency to discard white spaces, incorrectly
       interpret data or attempt to decode Base64 MIME encoded-words as
       Quoted-Printable.  These problems were fixed in version 2.22.  It is
       highly recommended not to use any version prior 2.22!

       Versions prior to 2.24 (part of Encode 2.87) ignored CHECK flags.  The
       MIME encoder used not strict utf8 encoder for input Unicode strings
       which could lead to invalid UTF-8 sequences.  MIME decoder used also
       not strict utf8 decoder and additionally called the decode method with
       a "Encode::FB_PERLQQ" flag (thus user-specified CHECK flags were
       ignored).  Moreover, it automatically croaked when a MIME encoded-word
       contained unknown encoding.  Since version 2.24, this module uses
       strict UTF-8 encoder and decoder.  And CHECK flags are correctly
       propagated.

       Since version 2.22 (part of Encode 2.83), the MIME encoder should be
       fully compliant to RFC 2047 <https://tools.ietf.org/html/rfc2047> and
       RFC 2231 <https://tools.ietf.org/html/rfc2231>.  Due to the
       aforementioned bugs in previous versions of the MIME encoder, there is
       a less strict compatible mode for the MIME decoder which is used by
       default.  It should be able to decode MIME encoded-words encoded by pre
       2.22 versions of this module.  However, note that this is not correct
       according to RFC 2047 <https://tools.ietf.org/html/rfc2047>.

       In default not strict mode the MIME decoder attempts to decode every
       substring which looks like a MIME encoded-word.  Therefore, the MIME
       encoded-words do not need to be separated by white space.  To enforce a
       correct strict mode, set variable $Encode::MIME::Header::STRICT_DECODE
       to 1 e.g. by localizing:

         use Encode::MIME::Header;
         local $Encode::MIME::Header::STRICT_DECODE = 1;


AUTHORS

       Pali <pali@cpan.org>


SEE ALSO

       Encode, RFC 822 <https://tools.ietf.org/html/rfc822>, RFC 2047
       <https://tools.ietf.org/html/rfc2047>, RFC 2231
       <https://tools.ietf.org/html/rfc2231>



perl v5.26.1                      2017-07-18         Encode::MIME::Header(3pm)

perl 5.26.1 - Generated Sat Nov 4 14:26:54 CDT 2017
© manpagez.com 2000-2017
Individual documents may contain additional copyright information.