X-Git-Url: https://git.phdru.name/?a=blobdiff_plain;f=mimedecode.docbook;h=382fba2cb2f6a79b998c12b3f7661c14fb7eb046;hb=fa51f1e417da0f8d66649ebe67c78a58b1b88eae;hp=5be05a8beb63f135a3a32d77203ba255463783d6;hpb=5522e44bc2b98380da3ba857b348f0e48bd47c9f;p=mimedecode.git diff --git a/mimedecode.docbook b/mimedecode.docbook index 5be05a8..382fba2 100644 --- a/mimedecode.docbook +++ b/mimedecode.docbook @@ -44,12 +44,24 @@ + + + + + + + + + + + + @@ -67,13 +79,13 @@ DESCRIPTION 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. + 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. @@ -81,42 +93,44 @@ much desirable. - 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. + 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, 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. + 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 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. + 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 consulted for charset. If it is not equal to -current default charset the body text recoded. Finally message headers and body -flushed to stdout. + 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. @@ -148,8 +162,8 @@ flushed to stdout. -c - Recode different character sets in message body to current default - charset; this is the default. + Recode different character sets in message bodies to the current + default charset; this is the default. @@ -158,7 +172,7 @@ flushed to stdout. -C - Do not recode character sets in message body. + Do not recode character sets in message bodies. @@ -173,12 +187,24 @@ flushed to stdout. + + -H hostname + --host=hostname + + + Use this hostname in X-MIME-Autoconverted headers instead of the + current hostname. + + + + -d header Add the header to a list of headers to decode; initially the list - contains headers "From" and "Subject". + contains headers "From", "To", "Cc", "Reply-To", "Mail-Followup-To" + and "Subject". @@ -196,9 +222,10 @@ flushed to stdout. -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". + 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". @@ -207,7 +234,37 @@ flushed to stdout. -P - Clear the list of headers' parameters to decode (make it empty). + 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. @@ -269,11 +326,11 @@ 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: + 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: @@ -284,15 +341,15 @@ else. Easy: - 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). + 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). @@ -320,12 +377,13 @@ the program always uses the default decoding. 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 with the wrong charset. + 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.