On Mon, Feb 09, 2009 at 10:24:38AM +0000, Ian Eiloart wrote:
>
>
> --On 7 February 2009 02:36:36 -0200 Carlos Horowicz
> <carlos.horowicz@xxxxxxxxx> wrote:
>
>> I'm wondering what to do in a live system with may be hundreds of
>> thousands of these strange e-mails already in users´ mailboxes,
My god, that many? Nuke it from orbit. Only way to be sure.
(alternative plan, grep for the bogus files, unlink them and
reconstruct the mailboxes - cheaper and less radioactive)
>> Should imapd be patched so that it just ignores the repetitions , both
>> when building cyrus.cache and when it returns the headers to a client
>> ? or should imapd really modify the original e-mail by stripping
>> unnecessary/illegal headers and store a cleaned-up version ?
>
> It shouldn't be modifying messages. It should handle such messages
> elegantly. Ignoring repetitions (beyond a threshold of repeats) seems the
> most sensible option. However, failing to report them to a client could
> cause confusion, so a threshold should be reasonably high. Of course some
> headers are supposed to have multiple instances...
Ditto with that. This patch ignores repetitions beyond a threshold. It
turns out that ignoring specific headers separately is hard[tm], but
just stopping parsing them after a count is way-easy.
> Alerting the system administrator to the existence of such bogus messages
> seems like a good idea, too. Perhaps through the logging system.
Yeah, good point. Allow me to add that.
> If you don't want a particular message in the system, then it should not
> be accepted by LMTP or by any IMAP message creation mechanism.
Ditto. Gosh. That makes 3 tunables. The gods of tunable
non-proliferation will want my head for doing this:
maxcacheheaders_warn = 500
maxcacheheaders_skip = 1000 (same as the current patch)
maxcacheheaders_reject = 2000
Sound like reasonable defaults? I'm tempted to make the _reject be '0'
(don't reject) by default.
Bron.
Max header lines == 1000 by default to avoid supersized cache records
--- a/imap/message.c
+++ b/imap/message.c
@@ -660,6 +660,7 @@ struct boundary *boundaries;
int left, len;
char *next;
int sawboundary = 0;
+ int max_header_lines = config_getint(IMAPOPT_MAXHEADERLINES);
body->header_offset = msg->offset;
@@ -715,6 +716,8 @@ struct boundary *boundaries;
for (next = headers; *next; next++) {
if (*next == '\n') {
body->header_lines++;
+ if (max_header_lines && body->header_lines > max_header_lines)
+ continue; /* we still want to get the full line count */
/* Check for headers in generic cache */
if (body->cacheheaders.start &&
diff --git a/lib/imapoptions b/lib/imapoptions
index b17d831..43433e0 100644
--- a/lib/imapoptions
+++ b/lib/imapoptions
@@ -566,6 +566,10 @@ are listed with ``<none>''.
/* Notifyd(8) method to use for "MAIL" notifications. If not set, "MAIL"
notifications are disabled. */
+{ "maxheaderlines", 1000, INT }
+/* Maximum number of lines of header that will be processed into cache
+ records. Default 1000. If set to zero, it is unlimited. */
+
{ "maxmessagesize", 0, INT }
/* Maximum incoming LMTP message size. If non-zero, lmtpd will reject
messages larger than \fImaxmessagesize\fR bytes. If set to 0, this
--
1.5.6.3
----
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