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mime: FormatMediaType fails to detect non-ASCII bytes #28849
Description
What version of Go are you using (go version)?
go version go1.11.2 linux/amd64
Does this issue reproduce with the latest release?
yeah.
What operating system and processor architecture are you using (go env)?
irrelevant.
What did you do?
https://play.golang.org/p/mkEHhue4cKm
Tried FormatMediaType with different unicode characters in parameter values.
What did you expect to see?
One of:
FormatMediaTypeencoding parameters with any unicode characters as per RFC 2231 section 4.FormatMediaTypeconsistently accepting all unicode characters. That's probably not really compliant with current standards, but works with few email clients I tried. I like RFC 6532, but it doesn't have any mention ofContent-TypeorContent-Dispositionthough, so this option can probably be ignored.FormatMediaTypeconsistently rejecting all characters impossible to represent by US-ASCII.
What did you see instead?
Only characters covered by ISO-8859-1 are detected as unicode and cause encoding failure.
Characters whose rune values (actual unicode values, not UTF-8 encoded) aren't & 0x80 pass test and are included in output.
Additional info & reporter's opinion
I noticed this looking at source code of FormatMediaType and noticing that it contains if character&0x80 != 0 check, however it iterates thru string with range value (not range []byte(value) which would be correct).
I really don't like that it doesn't at least support RFC 2231 encoding, now I will either need to reimplement this function myself, or encode filename parameter using either mime.BEncoding or mime.QEncoding.
Adding proper check there and failing to encode could cause some issues if implementations relied on old broken behavior, I guess.
Activity
[-]mime: FormatMediaType fails to detect unicode characters properly[/-][+]mime: FormatMediaType fails to detect non-ASCII bytes[/+]bcmills commentedon Nov 19, 2018
This issue seems like it is really two separate issues:
(1) is a bug-fix. (2) is a feature request; please file it separately.
bcmills commentedon Nov 19, 2018
CC @mpvl @bradfitz
andrius4669 commentedon Nov 19, 2018
gopherbot commentedon Nov 20, 2018
Change https://golang.org/cl/150417 mentions this issue:
mime: correctly detect non-ASCII characters in FormatMediaTypegopherbot commentedon Nov 20, 2018
Change https://golang.org/cl/150498 mentions this issue:
mime: remove allocation introduced in recent fixmime: remove allocation introduced in recent fix
mime: correctly detect non-ASCII characters in FormatMediaType
mime: remove allocation introduced in recent fix