mimedecode.py1mimedecode.pydecode MIME messagemimedecode.pyfilenameDESCRIPTION
Mail users, especially in non-English countries, often find that mail
messages arrived in different formats, with different content types, in
different encodings and charsets. Usually it is good because it allows to use
an appropriate format/encoding/whatever. Sometimes, though, some unification is
desirable. For example, one may want to put mail messages into an archive,
make HTML indices, run search indexer, etc. In such situations converting
messages to text in one character set and skipping some binary attachments is
much desirable.
Here is the solution - mimedecode.py!
It is a program to decode MIME messages. The program expects one input file
(either on the command line or on stdin) which is treated as an RFC822 message,
and decoded to stdout. If the file is not an RFC822 message it is just piped to
stdout as is. If the file is a simple RFC822 message it is just decoded as one
part. If it is a MIME message with multiple parts ("attachments") all parts are
decoded recursively. Decoding can be controlled by the command-line options.
First, Subject and Content-Disposition headers are examined. If any of those
exists, it is decoded according to RFC2047. Content-Disposition header is not
decoded - only its "filename" parameter. Encoded header parameters violate
the RFC, but widely deployed anyway, especially in the M$ Ophice GUI (often
referred as "Windoze") world, where programmers are often ignorant lamers who
never even heard about RFCs. Correct parameter encoding specified by RFC2231.
This program decodes RFC2231-encoded parameters, too.
Then the body of the message (or the current part) is decoded. Decoding
starts with looking at header Content-Transfer-Encoding. If the header
specifies non-8bit encoding (usually base64 or quoted-printable), the body
converted to 8bit. Then, if its content type is multipart (multipart/related or
multipart/mixed, e.g) every part is recursively decoded. If it is not
multipart, mailcap database is consulted to find a way to convert the body to
plain text. (I have no idea how mailcap could be configured on said M$ Ophice
GUI, please don't ask me; real OS users can consult my example at
http://phdru.name/Software/dotfiles/mailcap.html). The decoding process uses
first copiousoutput filter it can find. If there is no any filter the body just
passed unconverted.
Then Content-Type header consulted for charset. If it is not equal to
current default charset the body text recoded. Finally message headers and body
flushed to stdout.
OPTIONS-h-help
Print brief usage help and exit.
-V--version
Print version and exit.
-c
Recode different character sets in message body to current default
charset; this is the default.
-C
Do not recode character sets in message body.
-f charset
Force this charset to be the current default charset instead of
sys.getdefaultencoding().
-d header
Add the header to a list of headers to decode; initially the list
contains headers "From" and "Subject".
-D
Clear the list of headers to decode (make it empty).
-p header:param
Add the (header, param) pair to a list of headers' parameters to
decode; initially the list contains header "Content-Disposition",
parameter "filename".
-P
Clear the list of headers' parameters to decode (make it empty).
-b mask
Append mask to the list of binary content types; if the message to
decode has a part of this type the program will pass the part as is,
without any additional processing.
-e mask
Append mask to the list of error content types; if the message to
decode has a part of this type the program will raise ValueError.
-i mask
Append mask to the list of content types to ignore; if the message to
decode has a part of this type the program will not pass it, instead
a line "Message body of type `%s' skipped." will be issued.
-t mask
Append mask to the list of content types to convert to text; if the
message to decode has a part of this type the program will consult
mailcap database, find first copiousoutput filter and convert the
part.
The last 4 options (-beit) require more explanation. They allow a user
to control body decoding with great flexibility. Think about said mail
archive; for example, its maintainer wants to put there only texts, convert
Postscript/PDF to text, pass HTML and images as is, and ignore everything
else. Easy:
mimedecode.py -t application/postscript -t application/pdf -b text/html
-b 'image/*' -i '*/*'
When the program decodes a message (or its part), it consults
Content-Type header. The content type is searched in all 4 lists, in order
"text-binary-ignore-error". If found, appropriate action performed. If not
found, the program search the same lists for "type/*" mask (the type of
"text/html" is just "text"). If found, appropriate action performed. If not
found, the program search the same lists for "*/*" mask. If found,
appropriate action performed. If not found, the program uses default
action, which is to decode everything to text (if mailcap specifies
a filter).
Initially all 4 lists are empty, so without any additional parameters
the program always uses the default decoding.
ENVIRONMENT
LANG
LC_ALL
LC_CTYPE
Define current locale settings. Used to determine current default
charset (if your Python is properly installed and configured).
BUGS
The program may produce incorrect MIME message. The purpose of the program
is to decode whatever it is possible to decode, not to produce absolutely
correct MIME output. The incorrect parts are obvious - decoded Subject headers
and filenames. Other than that output is correct MIME message. The program does
not try to guess whether the headers are correct. For example, if a message
header states that charset is iso8859-5, but the body is actually in koi8-r -
the program will recode the message to the wrong charset.
AUTHOR
Oleg Broytman <phd@phdru.name>
COPYRIGHT
Copyright (C) 2001-2013 PhiloSoft Design
LICENSE
GNU GPL
NO WARRANTIES
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
SEE ALSO
mimedecode.py home page: http://phdru.name/Software/Python/#mimedecode