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2021-02-07imap: avoid unnecessary on-stack delete
None of the Content-Type attributes are long-lived (and unlikely to be memory intensive). While these callsites won't trigger $DB::args segfaults via confess or longmess, it'll make future code audits easier. cf. commit 0795b0906cc81f40 ("ds: guard against stack-not-refcounted quirk of Perl 5")
2021-01-05imap: fix uninitialized var on MSN search miss
It seems only triggered by bots trying to steal information.
2021-01-01update copyrights for 2021
Using "make update-copyrights" after setting GNULIB_PATH in my config.mak
2020-12-28search: remove {mset} option for ->mset method
The ->mset method always returns a Xapian mset nowadays, so naming a parameter {mset} is too confusing. As it does with MiscSearch, setting the {relevance} parameter to -1 now sorts by ascending docid order. -2 is now supported for descending docid order, too, since it may be useful for lei users.
2020-12-17imap: rename parse_query => parse_imap_query
Avoid confusing hackers since this conflicts with a method name provided by (Search::)Xapian::QueryParser.
2020-12-05imap: support isearch and reduce Xapian queries
Since IMAP search (either with Isearch or traditional per-Inbox search) only returns UIDs, we can safely set the limit to the UID slice size(*). With isearch, we can also trust the Xapian result to fit any docid range we specify. Limiting Xapian results to 1000 was making ->ALL docid <=> per-Inbox UID impossible since results could overlap between ranges unpredictably. Finally, we can map the ->ALL docids into per-Inbox UIDs and show them to the client in the UID order of the Inbox, not the docid order of the ->ALL extindex. This also lets us get rid of the "uid:" query parser prefix and use the Xapian::Query API directly to reduce our search prefix footprint. For mbox.gz downloads in WWW, we'll also make a best effort to preserve the order from the Inbox, not the order of extindex; though it's possible large result sets can have non-overlapping windows. (*) by definition, UID slice size is a "safe" value which shouldn't OOM either the server or clients.
2020-10-30tls: epollbit: account for miscellaneous OpenSSL errors
Apparently they happen (triggered by my -imapd instance), so bail out by closing the underlying socket rather than stopping the event loop and daemon process.
2020-09-26imap: avoid raising exception if client disconnects
This ought to save a few cycles if a client disconnects while in the middle of a (UID) FETCH. This avoids: Can't call method "git" on an undefined value at .../PublicInbox/IMAP.pm errors in stderr.
2020-09-19gcf2: wire up read-only daemons and rm -gcf2 script
It seems easiest to have a singleton Gcf2Client client object per daemon worker for all inboxes to use. This reduces overall FD usage from pipes. The `public-inbox-gcf2' command + manpage are gone and a `$^X' one-liner is used, instead. This saves inodes for internal commands and hopefully makes it easier to avoid mismatched PERL5LIB include paths (as noticed during development :x). We'll also make the existing cat-file process management infrastructure more resilient to BOFHs on process killing sprees (or in case our libgit2-based code fails on us). (Rare) PublicInbox::WWW PSGI users NOT using public-inbox-httpd won't automatically benefit from this change, and extra configuration will be required (to be documented later).
2020-09-15imap: quiet uninitialized variable warning on FETCH
This was triggered by blindly trying to FETCH an MSN (not "UID FETCH") on an empty dummy inbox. It's harmless, and probably triggered by a wayward client or misbehaving bot.
2020-09-03imap: drop old, pre-Parse::RecDescent search parser
We switched to Parse::RecDescent during development and left some dead code behind.
2020-09-03search: replace ->query with ->mset
Nearly all of the search uses in the production code rely on a Xapian mset iterator being returned (instead of an array of $smsg objects). So default to returning the mset and move the burden of smsg array conversion into the test cases.
2020-08-20search: add mset_to_artnums method
We can avoid importing mdocid() in several places by using this method, simplifying callers.
2020-08-20search: export mdocid subroutine
No need to have awkward globrefs for this.
2020-07-26imap: introduce and use Git->async_prefetch
We can keep the git process more active by sending another request to it while fetch_run_ops() is running. This parallelization speeds up mutt's initial FETCH for headers by around ~35%(!).
2020-07-10imap: avoid warnings on non-slice mailboxes
Non-slice mailboxes never have messages themselves, so we must not assume a message exists when sending untagged EXISTS messages.
2020-07-06daemon: warn on missing blobs
Since -edit and -purge should be rare and TOCTOU around them rarer still; missing {blobs} could be indicative of a real bug elsewhere. Warn on them. And I somehow ended up with 3 different field names for Inbox objects. Perhaps they'll be made consistent in the future.
2020-06-28ds: remove fields.pm usage
Since the removal of pseudo-hash support in Perl 5.10, the "fields" module no longer provides the space or speed benefits it did in 5.8. It also does not allow for compile-time checks, only run-time checks. To me, the extra developer overhead in maintaining "use fields" args has become a hassle. None of our non-DS-related code uses fields.pm, nor do any of our current dependencies. In fact, Danga::Socket (which DS was originally forked from) and its subclasses are the only fields.pm users I've ever encountered in the wild. Removing fields may make our code more approachable to other Perl hackers. So stop using fields.pm and locked hashes, but continue to document what fields do for non-trivial classes.
2020-06-27imap: EXAMINE: avoid potential race conditions
We need to rely on num_highwater for UIDNEXT since the highest `num' stored in over.sqlite3 may be rolled back if the most recent messages were spam. We also need to load the uo2m immediately on EXAMINE to ensure EXISTS responses are always consistent with regard to future updates.
2020-06-27imap: always send EXISTS on uo2m_extend
Clients which are NOT in an IDLE state still need to be notified of message existence. Unlike the EXPUNGE response, untagged EXISTS responses seem to be allowed at any time according to RFC 3501. We'll also perform uo2m_extend on the NOOP command, since NOOP is the recommended command for message polling.
2020-06-25git_async_cat: remove circular reference
While this circular reference was carefully managed to not leak memory; it was still triggering a warning at -imapd/-nntpd shutdown due to the EPOLL_CTL_DEL op failing after the $Epoll FD gets closed. So remove the circular reference by providing a ref to `undef', instead.
2020-06-23imap: refill_xap: remove needless loop
There's no need to loop when the first iteration guarantees a `return'.
2020-06-16imap: fix UID-offset-to-MSN mapping bugs
We need to clear the UID-offset-to-MSN mapping when leaving mailboxes via EXAMINE/SELECT/CLOSE. Furthermore, uo2m_last_uid() needs to account for tiny mailboxes where the scalar representation of {uo2m} may be evaluated to `false' in a boolean context.
2020-06-16imap: *SEARCH: fix CHARSET handling
We no longer pass an arrayref to search_common() or parse_query(), so handle the CHARSET directive in the Parse::RecDescent-generated parser directly.
2020-06-16imap: *SEARCH: use Parse::RecDescent
For properly parsing IMAP search requests, it's easier to use a recursive descent parser generator to deal with subqueries and the "OR" statement. Parse::RecDescent was chosen since it's mature, well-known, widely available and already used by our optional dependencies: Inline::C and Mail::IMAPClient. While it's possible to build Xapian queries without using the Xapian string query parser; this iteration of the IMAP parser still builds a string which is passed to Xapian's query parser for ease-of-diagnostics. Since this is a recursive descent parser dealing with untrusted inputs, subqueries have a nesting limit of 10. I expect that is more than adequate for real-world use.
2020-06-16imap: reinstate non-UID SEARCH
Since we support MSNs properly, now, it seems acceptable to support regular SEARCH requests in case there are any clients which still use non-UID SEARCH.
2020-06-16imap: stop_idle: fix parameter parsing :x
stop_idle was a noop when the client issues a "DONE" continuation or just disconnects. This would not have led to a long term memory leak since FDs get closed and reused, anyways, and all of our InboxIdle mappings are keyed by FD.
2020-06-16imap: improve IDLE handling at graceful shutdown
Since IMAP IDLE users aren't expected to issue any commands, we can terminate their connections immediately on graceful shutdown. Furthermore, we need to drop the inotify FD from the epoll set to avoid warnings during global destruction. Embarassingly, this required fixing wacky test ordering from 2a717d13f10fcdc6 ("nntpd+imapd: detect replaced over.sqlite3")
2020-06-16imap: clarify "DONE" usage with IDLE
"DONE" is a continuation and not a normal IMAP command, so ensure it can't be called like a normal IMAP command which has a tag.
2020-06-13imap: introduce memory-efficient uo2m mapping
Since we limit our mailboxes slices to 50K and can guarantee a contiguous UID space for those mailboxes, we can store a mapping of "UID offsets" (not full UIDs) to Message Sequence Numbers as an array of 16-bit unsigned integers in a 100K scalar. For UID-only FETCH responses, we can momentarily unpack the compact 100K representation to a ~1.6M Perl array of IV/UV elements for a slight speedup. Furthermore, we can (ab)use hash key deduplication in Perl5 to deduplicate this 100K scalar across all clients with the same mailbox slice open. Technically we can increase our slice size to 64K w/o increasing our storage overhead, but I suspect humans are more accustomed to slices easily divisible by 10.
2020-06-13imap: FETCH: proper MSN => UID mapping for requests
This finally seems to make mutt header caching behave properly. We expect to be able to safely load 50K IV/UVs in memory without OOM, since that's "only" 1.6 MB that won't live beyond a single event loop iteration. So create a simple array which can quickly map MSNs in requests to UIDs and not leave out messages. MSNs in the FETCH response will NOT be correct, since it's inefficient to implement properly and mutt doesn't seem to care. Since the conversion code is easily shared, "UID SEARCH" can allow the same MSN => UID mapping non-UID "FETCH" does.
2020-06-13imap: remove non-UID SEARCH for now
Supporting MSNs in long-lived connections beyond the lifetime of a single request/response cycle is not scalable to a C10K scenario. It's probably not needed, since most clients seem to use UIDs. A somewhat efficient implementation I can come up uses pack("S*" ...) (AKA "uint16_t mapping[50000]") has an overhead of 100K per-client socket on a mailbox with 50K messages. The 100K is a contiguous scalar, so it could be swapped out for idle clients on most architectures if THP is disabled. An alternative could be to use a tempfile as an allocator partitioned into 100K chunks (or SQLite); but I'll only do that if somebody presents a compelling case to support MSN SEARCH.
2020-06-13imap: misc cleanups and notes
Note some of our limitations for potential hackers. We'll be renaming "UID_BLOCK" to "UID_SLICE", since "block" is overused term and "slice" isn't used in our codebase. Also, document how "slice" and "epochs" are similar concepts for different clients.
2020-06-13imap: wire up Xapian, MSN SEARCH and multi sequence-sets
Simple queries work, more complex queries involving parentheses, "OR", "NOT" don't work, yet. Tested with "=b", "=B", and "=H" search and limits in mutt on both v1 and v2 with multiple Xapian shards.
2020-06-13imap: UID SEARCH: support multiple ranges
We can share a bit of code with FETCH to refill UID ranges which hit the SQLite overview.
2020-06-13imap: STATUS/EXAMINE: rely on SQLite overview
We can get exact values for EXISTS, UIDNEXT using SQLite rather than calculating off $ibx->mm->max ourselves. Furthermore, $ibx->mm is less useful than $ibx->over for IMAP (and for our read-only daemons in general) so do not depend on $ibx->mm outside of startup/reload to save FDs and reduce kernel page cache footprint.
2020-06-13imap: FETCH: try to make fake MSNs sequentially
This appears to significantly improve header caching behavior with mutt. With the current public-inbox.org/git mirror(*), mutt will only re-FETCH the last ~300 or so messages in the final "inbox.comp.version-control.git.7" mailbox, instead of ~49,000 messages every time. It's not perfect, but a 500ms query is better than a >10s query and mutt itself spends as much time loading its header cache. (*) there are many gaps in NNTP article numbers (UIDs) due to spam removal from public-inbox-learn.
2020-06-13imap: further speed up HEADER.FIELDS FETCH requests
Since headers are big and include a lot of lines MUAs don't care about, we can skip the CRLF_HDR ops and just do the CRLF conversion in partial_hdr_get and partial_hdr_not. This is another 10-15% speedup for mutt w/o header caching.
2020-06-13imap: FETCH: more granular CRLF conversion
This speeds up requests from mutt for HEADER.FIELDS by around 10% since we don't waste time doing CRLF conversion on large message bodies that get discarded, anyways.
2020-06-13imap: cleanup ->{uid_base} usage
Ensure {uid_base} is always set, so we don't need to add `//' checks everywhere. Furthermore, this fixes a hard-to-test bug where the STATUS command would inadvertantly clobber {uid_base}.
2020-06-13imap: reinstate some message sequence number support
The performance problem with mutt not using header caches isn't fixed, yet, but mutt header caching seems to depend on MSNs (message sequence numbers). We'll switch to storing the 0-based {uid_base} instead of the 1-based {uid_min} since it simplifies most of our code.
2020-06-13imap: support 8000 octet lines
RFC 2683 section 3.2.1.5 recommends it: > For its part, a server should allow for a command line of at least > 8000 octets. This provides plenty of leeway for accepting reasonable > length commands from clients. The server should send a BAD response > to a command that does not end within the server's maximum accepted > command length. To conserve memory, we won't bother reading the entire line before sending the BAD response and disconnecting them.
2020-06-13imap: LIST shows "INBOX" in all caps
While selecting a mailbox is done case-insensitively, "INBOX" is special for the LIST command, according to RFC 3501 6.3.8: > The special name INBOX is included in the output from LIST, if > INBOX is supported by this server for this user and if the > uppercase string "INBOX" matches the interpreted reference and > mailbox name arguments with wildcards as described above. The > criteria for omitting INBOX is whether SELECT INBOX will > return failure; it is not relevant whether the user's real > INBOX resides on this or some other server. Thus, the existing news.public-inbox.org convention of naming newsgroups starting with "inbox." needs to be special-cased to not confuse clients. While we're at it, do not create ".0" for dummy newsgroups if they're selected, either.
2020-06-13imap: UID FETCH requires at least one data item
It seems required based on my reading of RFC 3501 for the non-UID "FETCH" command.
2020-06-13imap: rely on smsg->{bytes} for RFC822.SIZE
Since we started indexing the CRLF-adjusted size of messages, we can take an order-of-magnitude speedup for certain MUAs which fetch this attribute without needing much else. Admins are encouraged to --reindex existing inboxes for IMAP support, anyways. It won't be fatal if it's not reindexed, but some client bugs and warnings can be fixed and they'll be able to support more of IMAP.
2020-06-13imap: split ->logged_in attribute into a separate class
This is one boolean attribute not worth wasting space for. With 20000 sockets, this reduces RSS by around 5% at a glance, and locked hashes doesn't do us much good when clients use compression, anyways.
2020-06-13imap: 30 minute auto-logout timer
RFC 3501 section 5.4 requires this to be >= 30 minutes, 10x higher than what is recommended for NNTP. Fortunately our design is reasonably memory-efficient despite being Perl.
2020-06-13imap: IDLE: avoid extraneous wakeups, keep-alive
We should not waste memory for IDLE unless it's used on the most recent inbox slice. We also need to keep the IDLE connection alive regardless of $PublicInbox::DS::EXPTIME.
2020-06-13imap: UID FETCH: optimize (UID FLAGS) harder
We can speed up this common mutt request by another 2-3x by not loading the entire smsg from SQLite, just the UID.
2020-06-13imap: UID FETCH: optimize for smsg-only case
We can avoid loading the entire message from git when mutt makes a "UID FETCH" request for "(UID FLAGS)". This speeds mutt up by more than an order-of-magnitude in informal measurements.