mimedecode.pymimedecode.docbookOlegBroytmanphd@phdru.name2001-2014PhiloSoft Design.mimedecode.py1mimedecode.pydecode MIME messagemimedecode.pyinput_file
output_fileDESCRIPTION
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!
This is a program to decode MIME messages. The program expects one input
file (either on command line or on stdin) which is treated as an RFC822
message, and decodes to stdout or an output file. If the file is not an
RFC822 message it is just copied to the output one-to-one. If the file is a
simple RFC822 message it is decoded as one part. If it is a MIME message
with multiple parts ("attachments") all parts are decoded. Decoding can be
controlled by command-line options.
First, for every part the program removes headers and parameters listed with
-r and -R options. Then, Subject and Content-Disposition headers (and all
headers listed with -d and -p options) are examined. If any of those exists,
they are decoded according to RFC2047. Content-Disposition header is not
decoded - only its "filename" parameter. Encoded header parameters violate
the RFC, but widely deployed anyway by ignorant coders 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 can be configured on OSes other
than POSIX, please don't ask me; real OS users can consult my example at
http://phdru.name/Software/dotfiles/mailcap.html).
The decoding process uses the first copiousoutput filter it can find. If
there are no filters the body just passed as is.
Then Content-Type header is consulted for charset. If it is not equal to the
current locale charset and recoding is allowed the body text is recoded.
Finally message headers and the body are 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 bodies to the current
default charset; this is the default.
-C
Do not recode character sets in message bodies.
-f charset
Force this charset to be the current default charset instead of
the current locale.
-H hostname--host=hostname
Use this hostname in X-MIME-Autoconverted headers instead of the
current hostname.
-d header1[,header2,header3...]
Add the header(s) to a list of headers to decode; initially the
list contains headers "From", "To", "Cc", "Reply-To",
"Mail-Followup-To" and "Subject".
-D
Clear the list of headers to decode (make it empty).
-p header:param
Add the pair (header, param) to a list of headers parameters to
decode; initially the list contains header "Content-Type",
parameter "name" and header "Content-Disposition", parameter
"filename".
-P
Clear the list of headers parameters to decode (make it empty).
-r header
Add the header to a list of headers to remove completely; initially
the list is empty.
-R header:param
Add the pair (header, param) to a list of headers parameters to
remove; initially the list is empty.
--remove-params=header
Add the header to a list of headers from which all parameters will
be removed; initially the list is 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 fails with 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.
-o output_file
Useful to set the output file in case of redirected stdin:
mimedecode.py -o output_file < input_file
cat input_file | mimedecode.py -o output_file
The 4 list 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 (non-MIME or a non-multipart subpart of a
MIME message), 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.
ENVIRONMENTLANGLC_ALLLC_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
From/To/Cc/Reply-To/Mail-Followup-To/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 utf-8 the program
will recode the message with the wrong charset.
AUTHOROlegBroytmanphd@phdru.nameCOPYRIGHT
Copyright (C) 2001-2014 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