Re: [Dovecot] BINARY FETCH conversion issue

[Timo Sirainen]

On 30.4.2014, at 0.27, Michael M Slusarz slus...@curecanti.org wrote:

 Given this test message, with admittedly incorrect QP encoding:
..
 Dovecot 2.2 returns this:
 
 C: 5 UID FETCH 4464 (BINARY.PEEK[1])
 S: * 1 FETCH (UID 4464 BINARY[1] NIL)
 S: 5 OK Fetch completed.
 
 Contrast with, e.g., Cyrus 2.4:
 
 C: 6 UID FETCH 1 (BINARY.PEEK[1])
 S: * 1 FETCH (UID 1 BINARY[1] {57}
 S: [LITERAL DATA: 57 bytes]
 S: )
 S: 6 OK Completed (0.000 sec)
 
 (Cyrus FETCH output strips out the spurious non-encoding '=', IIRC).
 
 Not sure if this is an example of Cyrus' QP decoder being more robust (or 
 lenient) than Dovecot's.  Or whether this is intentional to return NIL for 
 this kind of bad data.

It was kind of intentional. Dovecot's istream-qp-decoder aborts when it finds 
anything broken. I guess it could simply skip errors, but I'm not sure how good 
idea that is either..

 Although if intentional, output should probably be a NO response with 
 UNKNOWN-CTE response code, since this appears to be an instance of the 
 server does not know how to decode the section's CTE. (RFC 3516 [4.3]).

Yeah, I think that's better. Fixed: 
http://hg.dovecot.org/dovecot-2.2/rev/197f77f6ef0d

Also this fix more or less requires this: 
http://hg.dovecot.org/dovecot-2.2/rev/99f59d6fce05

Re: [Dovecot] BINARY FETCH conversion issue

[Michael M Slusarz]

Quoting Timo Sirainen t...@iki.fi:


On 30.4.2014, at 0.27, Michael M Slusarz slus...@curecanti.org wrote:

Not sure if this is an example of Cyrus' QP decoder being more  
robust (or lenient) than Dovecot's.  Or whether this is intentional  
to return NIL for this kind of bad data.


It was kind of intentional. Dovecot's istream-qp-decoder aborts when  
it finds anything broken. I guess it could simply skip errors, but  
I'm not sure how good idea that is either..


I don't find it all that useful for a server to try to guess the best  
decoding results.


Instead, I'd rather be told that the part is broken thus giving me the  
option to download via a normal BODY FETCH ... since that allows me to  
resolve the decoding issue locally however I want.


Although if intentional, output should probably be a NO response  
with UNKNOWN-CTE response code, since this appears to be an  
instance of the server does not know how to decode the section's  
CTE. (RFC 3516 [4.3]).


Yeah, I think that's better. Fixed:  
http://hg.dovecot.org/dovecot-2.2/rev/197f77f6ef0d


Thanks.  I agree that this is the best solution.

michael