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From "Stefano Bagnara (JIRA)" <server-...@james.apache.org>
Subject [jira] Created: (MIME4J-58) Lenient dealing with headless messages or malformed header/body separation
Date Fri, 18 Jul 2008 11:22:33 GMT
Lenient dealing with headless messages or malformed header/body separation
--------------------------------------------------------------------------

                 Key: MIME4J-58
                 URL: https://issues.apache.org/jira/browse/MIME4J-58
             Project: Mime4j
          Issue Type: Task
    Affects Versions: 0.3
            Reporter: Stefano Bagnara
             Fix For: 0.5


Define how to deal with non canonical messages like this one:
-----------------------
This is a simple message not having headers.
The whole text should be recognized as body.
-----------------------
or this one:
-----------------------
Subject: this is a subject
This is an invalid header
AnotherHeader: is this an header or the first part of the body?

Body text
-----------------------

In the first case mime4j output twice an  "invalid header" error and a roundtrip write result
in an empty message.
In the SMTP case this is unfortunate because sometimes it happens messages are sent without
header.

In the second case mime4j currenlty take Subject and AnotherHeader as headers and "This is
an invalid header" raise a monitor for "invalid header" and "Body text" is considered the
body.

A compromise we evaluated in past between compliance, leniency and performace was to "alter"
the requirement for CRLFCRLF between headers and body with a different rule: if during parsing
of the headers we find a line (not multiline) and not including an "HeaderName: something"
then we virtually add a CRLF *before* that line and consider that line the first line of the
body. This allow us to only buffer a single line (as opposite to parsing the whole message
in search of a CRLFCRLF and consider the full message a body if no CRLFCRLF is found) and
to be very lenient with input. The "side effect" (maybe not bad) is that a wrong header in
the middle of headers will result in some headers moved to the body.

With this algorythm the above would be "virtually" parsed as it was:
-----------------------

This is a simple message not having headers.
The whole text should be recognized as body.
-----------------------
or this one:
-----------------------
Subject: this is a subject

This is an invalid header
AnotherHeader: is this an header or the first part of the body?

Body text
-----------------------

If we think about strict and lenient approaches I think that current mime4j result is ok when
using a strict parsing, while the one I propose is a good lenient alternative.

Opinions? Alternatives?

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