Hi.
Can exim unfold and decode entire multiline header (`Subject` particularly)?
Here is the first part of multiline header:
Subject:
=?UTF-8?B?RndkOiBVUkdFTlQ6IFtOb3RpY2UgSUQgKndtVVJwRCpdINCY0YHQv9C+?=\n
=?UTF-8?B?0LvRjNC30L7QstCw0L3QuNC1INC40L3RgtC10LvQu9C10LrRgtGD0LDQu9GM0L0=?=
I've tried several variants.
`$h_Subject:` decodes only until first newline:
Subj_h: Fwd: URGENT: [Notice ID *wmURpD*]
\320\230\321\201\320\277\320\276\n
=?UTF-8?B?0LvRjNC30L7QstCw0L3QuNC1INC40L3RgtC10LvQu9C10LrRgtGD0LDQu9GM0L0=?=\n
Then i've tried to use `sg` to replace newlines in raw header with comma and
use `reduce` to decode each part using `rfc2047d`, but that didn't work,
because it turns out exim is only able to decode the first chunk:
# exim -be
'${rfc2047d:=?UTF-8?B?RndkOiBVUkdFTlQ6IFtOb3RpY2UgSUQgKndtVVJwRCpdINCY0YHQv9C+?=}'
Fwd: URGENT: [Notice ID *wmURpD*] Испо
# exim -be
'${rfc2047d:=?UTF-8?B?0LvRjNC30L7QstCw0L3QuNC1INC40L3RgtC10LvQu9C10LrRgtGD0LDQu9GM0L0=?=}'
=?UTF-8?B?0LvRjNC30L7QstCw0L3QuNC1INC40L3RgtC10LvQu9C10LrRgtGD0LDQu9GM0L0=?=
But the second chunk is also valid base64:
# echo
'0LvRjNC30L7QstCw0L3QuNC1INC40L3RgtC10LvQu9C10LrRgtGD0LDQu9GM0L0=' |
base64 -d
льзование интеллектуальн
So, may be it's not valid per rfc2047, i don't know, but Thunderbird still
decodes the entire header successfully.. But that was only the decoding
part.
The other part was to add something to this header (and break DKIM, yes, i
remember, thanks Mike Brudenell for reminding me about this, when i
wanted to
modify attached file extension).
Here first i've tried to modify decoded header and then encode it with
`rfc2047`:
Subj_h2: ${rfc2047:***** VIRUS ***** $h_Subject:}
but that results in double-encoding:
Subj_h2:
=?UTF-8?Q?*****_VIRUS_*****_Fwd=3A_URGENT=3A_=5BNotice_ID_*wmURpD*=5D_?=
=?UTF-8?Q?=D0=98=D1=81=D0=BF=D0=BE=0A_=3D=3FUTF-8=3FB=3F0LvRjNC30L7Q?=
And the only method, that seems to output somethiing similar to correct,
is to
encode just the text i want to add and prepend it to raw header, like:
${rfc2047:***** VIRUS *****}\n $rh_Subject:
Subject: ***** VIRUS *****
=?UTF-8?B?RndkOiBVUkdFTlQ6IFtOb3RpY2UgSUQgKndtVVJwRCpdINCY0YHQv9C+?=
=?UTF-8?B?0LvRjNC30L7QstCw0L3QuNC1INC40L3RgtC10LvQu9C10LrRgtGD0LDQu9GM0L0=?=
So, is there something wrong with this particular `Subject` header or
exim always
decodes only first line of multiline header? And are there some
pitfalls, that
i didn't notice, when modifying header? Or may there is a better way to
do it?
--
Dmitriy
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