First we try the original MIME type unless it's application/octet-stream.
Then we try the MIME type inferred from the attachment's file extension.
Then we fall back to application/octet-stream.
In all cases we first try the content:// URI, then a file:// URI.
This builds upon the efforts started 2 commits back where \r\n is used for
all message text and \n is only used when the text is inside an
EolConvertingEditText widget.
The problem:
Configure the account (just an example -- problems can occur in other
configurations as well):
Message Format: HTML
Reply quoting style: Prefix
Quote message when replying: yes
Reply after quoted text: yes
Reply to a message that has a large quantity (20+) of \r\n scattered in
the body of its HTML version (not an unusual scenario).
Add a reply. Save the message as a draft. Go back & open the draft
again. A fatal IndexOutOfBoundsException occurs.
The cause:
When the draft was saved, the X-K9mail-Identity header was computed and
added to the message, then the text of the message was processed with
MimeUtility.fixDraftTextBody, replacing all occurrences of \r\n with \n in
the quoted message before being saved in LocalStore, thus invalidating the
X-K9mail-Identity header.
The fix:
Remove MimeUtility.fixDraftTextBody and implement
MessageCompose$EolConvertingEditText instead. Any message text placed in
an EolConvertingEditText widget is assured to have \n line endings. Any
message text extracted from an EolConvertingEditText widget is assured to
have \r\n line endings. The X-K9mail-Identity header will always be
computed correctly.
Issues thought to be related: 4782, 5010, 5634, 5725
As noted in some of the referenced issues, errors didn't always result in
a fatal exception, but instead with mixed up text.
Ref: commit f9a35aeaee
Fix the unit test to match.
All line endings in the unit test are now the same.
(Just for consistency. Not a big deal, since such problems are fixed when
the messages are run through EOLConvertingOutputStream.)
The preceding commit resulted in attachments of type message/rfc822 being
sent with 8bit encoding even when the SMTP server did not support
8BITMIME. This commit assures that messages will be converted to 7bit
when necessary.
A new interface CompositeBody was created that extends Body, and classes
Message and Multipart were changed from implementing Body to
CompositeBody. Additional classes BinaryTempFileMessageBody and
LocalAttachmentMessageBody were created (by extending BinaryTempFileBody
and LocalAttachmentBody, respectively), and they too implement
CompositeBody.
A CompositeBody is a Body containing a composite-type that can contain
subparts that may require recursive processing when converting from 8bit
to 7bit. The Part to which a CompositeBody belongs is only permitted to
use 8bit or 7bit encoding for the CompositeBody.
Previously, a Message was created so that it was 7bit clean by default
(even though that meant base64 encoding all attachments, including
messages). Then, if the SMTP server supported 8BITMIME,
Message.setEncoding("8bit") was called so that bodies of type TextBody
would been transmitted using 8bit encoding rather than quoted-printable.
Now, messages are created with 8bit encoding by default. Then, if the
SMTP server does not support 8BITMIME, Message.setUsing7bitTransport is
called to recursively convert the message and its subparts to 7bit. The
method setUsing7bitTransport was added to the interfaces Part and
CompositeBody.
setEncoding no longer iterates over parts in Multipart. That task belongs
to setUsing7bitTransport, which may in turn call setEncoding on the parts.
MimeUtility.getEncodingforType was created as a helper function for
choosing a default encoding that should be used for a given MIME type when
an attachment is added to a message (either while composing or when
retrieving from LocalStore).
setEncoding was implemented in MimeBodyPart to assure that the encoding
set in the Part's headers was the same as set for the Part's Body. (The
method already existed in MimeMessage, which has similarities with
MimeBodyPart.)
MimeMessage.parse(InputStream in, boolean recurse) was implemented so that
the parser could be told to recursively process nested messages read from
the InputStream, thus giving access to all subparts at any level that may
need to be converted from 8bit to 7bit.
Issue 5734 exemplifies the problem: receive a message with an attachment
of type message/rfc822 that doesn't use base64 encoding for the body of
the attached message. K-9 Mail incorrectly stores the attached message
locally with its original headers but using base64 encoding for the body.
A discrepancy thus exists between what the headers say about the encoding
of the body versus the actual encoding used. This is obvious when
attempting to view the attachment (either by using a compatible message
viewer available on the device or by saving the attachment to a file and
viewing the file contents).
The process: When a message with an attached sub-message is received,
Message.parse puts the attachment in a new MimeMessage with the
attachment's body in a BinaryTempFileBody. LocalFolder.saveAttachment
then calls Message.writeTo (which later calls BinaryTempFileBody.writeTo)
to place the entire attachment (headers and body) in a new file that will
become a LocalAttachmentBody. Until now, BinaryTempFileBody.writeTo
could only save the message body using base64 encoding.
This commit implements BinaryTempFileBody.setEncoding and assures that the
body is written out with the same encoding that was found in its headers.
Previously, <html>, <head>, & <body> tags were
attached to messages before they were stored locally.
But now that the <head> element also needs to include
a <meta> element (for proper MessageWebView display),
it seems unecesary to store all these tags with each
message.
Now the tags are no longer stored with the messages. Instead,
MessageWebView applies the tags before displaying the message.
This also eliminates the need to upgrade an older
message database where all the old messages would have
otherwise needed to be wrapped with the new tags.
This is necessary because we save the offset and length of the user-
supplied text in the identity header. These values are then later used
to split the draft in user text and quoted message.
When calculating these values we operate on a string with LF line
endings. Ideally we want to do the reverse operation on the same
string, but when saving the message to the server LF is converted to
CRLF to create RFC-conforming messages.
This is only a hack and will probably be the cause of more trouble in
the future. A better solution would be to make the identity header more
robust or get rid of it entirely.
Jan Berkel