[ mailman-Bugs-1461279 ] Filtering content while allowing HTML messages impossible
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Fri Mar 31 09:05:00 CEST 2006
Bugs item #1461279, was opened at 2006-03-30 12:41
Message generated for change (Comment added) made by psy-q
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Category: None
Group: 2.1 (stable)
Status: Open
Resolution: None
>Priority: 2
Submitted By: - (psy-q)
Assigned to: Nobody/Anonymous (nobody)
Summary: Filtering content while allowing HTML messages impossible
Initial Comment:
I hope this is a genuine bug. I'll use 2.1.7 in these
examples, though I verified this behavior in 2.1.5
also.
I have a mailing list configured as such:
filter_content = 1
filter_mime_types = ''
pass_mime_types = """multipart/mixed
multipart/alternative
text/plain
text/html"""
collapse_alternatives = 0
convert_html_to_plaintext = 0
filter_action = 2
And yet all HTML messages are automatically stripped
of HTML, have their attachments removed and are
immediately posted to the list.
The originals are sent as multipart/alternative with
two attachments, one the text/plain rendition of the
message and one the text/html original. It seems to
be okay, user agents can render this message as
intended. All that remains when delivered by Mailman
is the text/plain bit, though.
Shouldn't this list configuration let HTML mails
through? I can't see a reason why Mailman should
remove the HTML silently with these settings.
If filter_content is turned off, sending HTML
messages works.
(I know it's not polite to send HTML messages through
mailing lists, but some of my users insist.)
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>Comment By: - (psy-q)
Date: 2006-03-31 09:04
Message:
Logged In: YES
user_id=244049
Thanks for clearing that up, you've confirmed most of what
I've only had vague suspicions about :)
I found out about 2.1.5's hardcoded collapse_alternatives
behavior about half an hour after posting my bug, but
thanks for confirming it.
I feel like a fool at the moment. I just retried this so I
could give you example messages, and the behavior has
stopped. I reproduced the unwanted filtering for over an
hour yesterday, I have no idea why it's working correctly
now. Yesterday, I tried about a dozen combinations of
filter strings and settings, none of which produced the
desired result. In the end, I returned to the
configuration that I posted here and performed a final
test to verify that the behavior is indeed confusing.
Today, I switched my test MTA back on, switched Mailman
back on and tried the very same test message as yesterday.
Amazingly, it went through exactly as expected. Then I
removed text/html from pass_mime_types, and again it
behaved exactly as advertised: It let the
multipart/alternative message through, kept the text/plain
part intact but removed the text/html. This is completely
different behavior than I saw yesterday.
So now I'm even more confused than before -- In theory,
this means that an upgrade to 2.1.7 using this list
configuration would make everything work as it should at
my site, and it would mean that there is no bug.
I will test a bit more thoroughly, I'll remove Mailman and
do a vanilla install of 2.1.7 to see if I can get the
behavior to show again.
----------------------------------------------------------------------
Comment By: Mark Sapiro (msapiro)
Date: 2006-03-31 03:00
Message:
Logged In: YES
user_id=1123998
You can't really compare 2.1.5 and 2.1.7 in this respect
since 2.1.5 doesn't have the collapse_alternatives setting
and always operates as if collapse_alternatives is true
(non-zero). I.e., 2.1.5 will always replace a
multipart/alternative part with just the first alternative.
Also, your "immediately posted" remark makes me think that
you think filter_action applies whenever content is filtered
in any way. This is not true. filter_action only applies
when the message is empty after filtering.
You also say "yet all HTML messages are automatically
stripped of HTML, have their attachments removed and ...". I
think you may or may not have a misconception here. With the
pass_mime_types settings you have given, no attachments of
any type other than text/plain or text/html should be left
in the message. The types multipart/alternative and
multipart/mixed only allow such messages/parts to be further
processed looking for allowable types. I.e, with these
settings a message or part of type multipart/related will be
filtered completely (nothing left) regardless of what it
contains, because multipart/related is not accepted.
On the other hand, a message or part of type multipart/mixed
will have it's sub-parts examined for allowable types
because multipart/mixed is allowed.
So the only issue is why are text/html parts being removed
in 2.1.7 from multipart/mixed and/or multipart/alternative
parts. This may or may not be a bug. Please attach full
copies of a message both before and after filtering
including all headers to this report, so we can see if there
is a bug or what the problem might be.
Note that your description of the multipart/alternative
messages and results is the only way Mailman 2.1.5 works so
there is no bug there. In 2.1.7 with collapse_alternatives =
0 and text/html in pass_mime_types, the html should remain
in the outgoing message, so there is clearly a problem here.
----------------------------------------------------------------------
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