Tickets :: Comment on [#3565] Attachment modification (newline structure changes)

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Comment	> From imp@lists: > > > > Quoting "Daniel A. Ramaley" <daniel.ramaley@DRAKE.EDU>: > > > >> There has been an off-list discussion that should be part of this > >> thread. Both parties agree that it should be posted back to the list. > >> It follows, with most quoted text removed: > >> > >> > >> > >> Date: Tue, 25 Apr 2006 16:54:06 +0200 > >> From: Andreas Geesen > >> > >> I experienced bad behaviour when attachments got encoded as > >> "quoted-printable". Can you confirm that this is the case with your > >> file, too? > >> If so take a look at the bytes of the original and the broken file. If > >> they differ in the way EOL is used (0x0d 0x0a vs. 0x0a) you have the > >> same prob which i had. > > > > [snip] > > > > This is the same discussion as appeared on the bug report and, > unfortunately, this discussion is still incorrect. > > > > As mentioned in the bug report - this is not a Horde/IMP issue. This > is an issue with quoted-printable not being able to handle binary > data UNLESS IT IS EXPLICTLY TOLD IT IS BEEN GIVEN BINARY DATA. More > important, this issue has nothing to do with EOL characters - or, > more correctly, messing with EOL characters is absoultely the wrong > way to look at this issue. > > > > Maybe a simple example will be in order. Say I have the following > text/plain file: > > > > ----- > > Line one.CR > > Line two. > > ----- > > > > And i send it in quoted-printable. It will be sent as the following: > > > > ----- > > Line one.CRLF > > Line two. > > ----- > > > > As can be seen, pursuant to RFCs, all end of line characters are > converted to CRLF. Most important, no matter what OS the message is > read on, that OS can convert the CRLF string to whatever EOL > convention that OS uses - this is part of the decoding of an RFC > message on the receiving end. So the message appears with the same > line breaks no matter what OS is used to read the message. What is > important to realize is that this text message WILL BE DIFFERENT > depending on the OS used. On unix, the message will look like the > following: > > > > ----- > > Line one.LF > > Line two. > > ----- > > > > On windows the message will look like the following: > > > > ----- > > Line one.CRLF > > Line two. > > ----- > > > > As can be seen, the file length of the former file is 19. The file > length of the latter file is 20. Ack! What is going on? The > answer is nothing - as explained several times in the bug reports > this is exactly what the RFCs allow. Horde/IMP isn't broken. Since > it is text data, the difference is file sizes doesn't make any > difference since with textual data we only care about the display. > > > > But, exactly like the RFCs warn us, the problem occurs when we try to > use quoted-printable to send BINARY data. Using the same example as > above, lets assume that this message is not text data but is binary > data instead. Lets assume it is a windows based program that parses > this data, and this program delimits lines by CRLF. Lets assume > Horde/IMP is running on a UNIX machine. We go to attach our message > using IMP. So far so good since the message will be canonicalized > when sending to: > > > > ----- > > Line one.CRLF > > Line two. > > ----- > > > > Which just fortuitously happens to be in the format we need. Now > imagine this message is received on an IMP installation on a UNIX > machine. We go to download the file. The file is downloaded as such: > > > > ----- > > Line one.LF > > Line two. > > ----- > > > > And, no suprise, the file is in the wrong format. The windows > program can't read the file. People incorrectly point the finger at > Horde/IMP. > > > > So how could this latter situation happen? Because the file is > reported to IMP at the time of sending as a text file. As adequately > demonstrated above, the RFCs clearly indicate that EOL formatting is > not guaranteed when using quoted-printable encoding of text data. > Thus, there is nothing broken. There is either an issue with the > browser incorrectly identifying the file as text to IMP when > attaching, or there is an issue with MIME magic detection of the file. > > > > We don't support Q-P encoding of binary data. It defeats the whole > purpose of Q-P in the first place - Q-P is intended to provide a non > MIME-compliant reader (e.g. simple mail user agent, a user looking at > the raw text of the message) a way to understand the gist of the text > message without having to do any further processing. > > > > We are not going to send all messages in base64 since #1 it would > result in all messages being approximately 33% larger than they > should and #2 it does not provide the ability to quickly look at a > mail message without specialized software and still be able to > understand most (if not all) of the message > > > > Just FYI, to correctly Q-P binary data, the message above would have > to be sent as follows: > > ----- > > Line one.=0E=0CLine two. > > ----- > > > > But if we know the message is binary data, we are just going to > base64 encode it anyway since it is a more efficient way of sending > binary data (33% more efficient if the entire message is binary data) > and if a message is binary data, we don't need the feature of being > able to look at the message (e.g. Q-P) without specialized software > since the data is going to be indecipherable anyway. > > > > So if binary data is reported as text at the time of attachment then > there can be no expectation that the message will be transmitted > through RFC-compliant mail without alteration. As mentioned > previously, there may be two reasons why binary data is attached as > text: > > 1.) browser reports data as text/* > > This is a browser issue. > > SOLUTION: Fix your browser. Or hack Horde/IMP to send all messages > in base64. But this will neither become an option or the standard in > our codebase > > 2.) MIME magic reports application/octet-stream data as text/* > > This may or may not be a Horde issue. This is only a Horde issue if > our internal MIME magic detection is used. But this is the third > option and is only used if both the PECL fileinfo module is not > installed and the PHP mime_magic extesion is not available. If > either of these modules are used, then the issue is with their mime > magic algorithims which is something out of the control of us. > > > > In conclusion, there is absolutely nothing wrong with the way we send > Q-P data since we only Q-P encode a message if we are dealing with > text data. This is why Bug 3565 was correctly marked Bogus.
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