Excessive APPENDLIMIT response [Re: Android after Cyrus upgrade]

Edda,
Great catch!  Indeed, the APPENDLIMIT extension, defined in RFC7889*, 
was added to Cyrus in 2021:

    commit 40793dfde8c96797d86f80e9f461bea61bca3bc9
    Author: Ken Murchison <[email protected]>
    Date:   Sat Jan 30 09:10:00 2021 -0500

         imapd.c: Advertise APPENDLIMIT= capability

As noted, this is defined in imap/imapc:

    { "APPENDLIMIT=",          CAPA_POSTAUTH|CAPA_VALUE,         /* RFC 7889 */
           { .value = { "%2$" PRIi64, .i64p = &maxsize } }         },

So the question becomes, is this a bug in Cyrus or in FairEmail? Given 
that FairEmail is the only application complaining about it, I'd suggest 
they're the buggy ones.  But I could be wrong.

*It's worth noting* that there's appears to be no configuration option 
[i.e. imapd.conf(5)] for appendlimit (looked for *limit, *maxsize, 
etc.).  Is this a bug?  The number advertised, 18446744071562067968, is 
the C compiler's maximum object size.  This seems awfully large for most 
mail systems, and doesn't serve any legitimate purpose as it currently sits.

Cheers,
     -nic


*https://www.rfc-editor.org/rfc/rfc7889


On 5/10/23 07:20, Edda wrote:
> Hello Vladas,
>
> FairEmail is complaining about a "too long" Long. It's in the source 
> code of FairEmail in 
> ./app/src/main/java//eu/faircode/email/EmailService.java at:
>
>     Long getMaxSize() throws MessagingException {
>         // https://support.google.com/mail/answer/6584#limit
>
>         String size;
>         if (iservice instanceof SMTPTransport) {
>             // https://tools.ietf.org/html/rfc1870
>             size = getTransport().getExtensionParameter("SIZE");
>         } else if (iservice instanceof IMAPStore) {
>             // https://tools.ietf.org/html/rfc7889
>             size = ((IMAPStore) iservice).getCapability("APPENDLIMIT");
>         } else
>             return null;
>
>         if (!TextUtils.isEmpty(size) && TextUtils.isDigitsOnly(size)) {
> *            long s = Long.parseLong(size);*
>             if (s != 0) // Not infinite
>                 return s;
>         }
>
>         return null;
>     }
>
> String "size" is indeed too long for a Long: "18446744071562067968"
>
> Since it's an IMAP Service, APPENDLIMIT seems to be the problem.
>
> I just checked at your server:
>
> . CAPABILITY
> * CAPABILITY IMAP4rev1 LITERAL+ ID ENABLE ACL ANNOTATE-EXPERIMENT-1 
> BINARY CATENATE CHILDREN CONDSTORE CREATE-SPECIAL-USE ESEARCH ESORT 
> LIST-EXTENDED LIST-MYRIGHTS LIST-STATUS MAILBOX-REFERRALS METADATA 
> MOVE MULTIAPPEND NAMESPACE OBJECTID PREVIEW QRESYNC QUOTA RIGHTS=kxten 
> SAVEDATE SEARCH=FUZZY SORT SORT=DISPLAY SPECIAL-USE STATUS=SIZE 
> THREAD=ORDEREDSUBJECT THREAD=REFERENCES UIDPLUS UNSELECT URLAUTH 
> URLAUTH=BINARY WITHIN DIGEST=SHA1 LIST-METADATA NO_ATOMIC_RENAME SCAN 
> SORT=MODSEQ SORT=UID THREAD=REFS X-CREATEDMODSEQ X-REPLICATION 
> X-SIEVE-MAILBOX XLIST XMOVE AUTH=SCRAM-SHA-512-PLUS AUTH=SCRAM-SHA-512 
> AUTH=SCRAM-SHA-384-PLUS AUTH=SCRAM-SHA-384 AUTH=SCRAM-SHA-256-PLUS 
> AUTH=SCRAM-SHA-256 AUTH=SCRAM-SHA-224-PLUS AUTH=SCRAM-SHA-224 
> AUTH=SCRAM-SHA-1-PLUS AUTH=SCRAM-SHA-1 AUTH=GSS-SPNEGO AUTH=GSSAPI 
> AUTH=DIGEST-MD5 AUTH=OTP AUTH=NTLM AUTH=CRAM-MD5 AUTH=LOGIN AUTH=PLAIN 
> SASL-IR XCONVERSATIONS COMPRESS=DEFLATE X-QUOTA=STORAGE 
> X-QUOTA=MESSAGE X-QUOTA=X-ANNOTATION-STORAGE X-QUOTA=X-NUM-FOLDERS 
> IDLE *APPENDLIMIT=18446744071562067968*
>
> APPENDLIMIT is advertised prior to login. Therefore it doesn't show up 
> in the telemetry logs I think.
>
> I don't have cyrus 3.6.1 anywhere yet, but I think you should look at 
> maxmessagesize in imapd.conf
>
> Best regards,
> Edda
>
>
> Am 09.05.23 um 14:20 schrieb vladas via Info:
>> I have read the man 
>> <https://sala.online.lt/doc/cyrus-imapd/html/imap/reference/manpages/index.html> 
>> pages, release 
>> <https://www.cyrusimap.org/imap/download/release-notes/3.6/x/3.6.0.html> 
>> and upgrade <https://www.cyrusimap.org/imap/download/upgrade.html> 
>> notes again,  checked cyrus.conf and imapd.conf settings, restarted 
>> Cyrus imapd and saslauthd daemons, verified configuration and spool 
>> files — and still found no cause.
>>
>> Then I completely removed my account and all assets from FairEmail on 
>> my Android Motorola phone, Asus pad, and then set them again 
>> manually, step by step, with different connection modes (SSL/TLS 
>> :933, STARTTLS :143, insecure) — all of them are accepted, but the 
>> sync soon gets stuck and a warning message is issued with always the 
>> same error code:
>>
>>> For input string: "1844674407152067968"
>>
>> FairEmail is the best MUA I have ever seen: lean, secure, fast, with 
>> a clear and convenient user interface — despite of being 
>> full-featured and standards-compliant, with hundred of preconfigured 
>> settings of commercial providers, and with detailed logs:
>>
>>
>>
>> My mail is hosted on sala.online.lt [217.147.40.110] and serves, 
>> among others, the on.lt domain. Faircode.eu is a domain of the 
>> developer. This log is laid out here from bottom to the top. Sorry, I 
>> am not a programmer and do not understand this log. I guess there is 
>> a tiny software bug, that only emerged after the upgrade.
>
>
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-- 
Nic [email protected]
https://www.nicbernstein.com

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