In dns_server_unlink_marked() and dns_server_mark_all() we done recursively.
People might have dozens of servers defined, and it's better to avoid recursion
when a simple loop suffices.
dns_server_unlink_marked() would only unmark the first marked server.
Fixes#19651.
We recently started making more use of malloc_usable_size() and rely on
it (see the string_erase() story). Given that we don't really support
sytems where malloc_usable_size() cannot be trusted beyond statistics
anyway, let's go fully in and rework GREEDY_REALLOC() on top of it:
instead of passing around and maintaining the currenly allocated size
everywhere, let's just derive it automatically from
malloc_usable_size().
I am mostly after this for the simplicity this brings. It also brings
minor efficiency improvements I guess, but things become so much nicer
to look at if we can avoid these allocation size variables everywhere.
Note that the malloc_usable_size() man page says relying on it wasn't
"good programming practice", but I think it does this for reasons that
don't apply here: the greedy realloc logic specifically doesn't rely on
the returned extra size, beyond the fact that it is equal or larger than
what was requested.
(This commit was supposed to be a quick patch btw, but apparently we use
the greedy realloc stuff quite a bit across the codebase, so this ends
up touching *a*lot* of code.)
In 0e0fd08fc8 I added reference counts to keep
track of the DnsQueryCandidate objects. Unfortunately, dns_query_unref_candidates()
was written as
while (q->candidates)
dns_query_candidate_unref(q->candidates);
i.e. it would keep dropping the reference count as many times as needed for it
to hit 0, making the patch less than fully effective.
dns_query_unref_candidates() is renamed to dns_query_detach_candidates() and
changed to drop exactly one reference from each of the linked candidates.
Example failure:
==463== Invalid read of size 8
==463== at 0x419C93: dns_query_candidate_go (resolved-dns-query.c:159)
==463== by 0x41A143: dns_query_candidate_notify (resolved-dns-query.c:304)
==463== by 0x434BD6: dns_transaction_complete (resolved-dns-transaction.c:437)
==463== by 0x436A0F: dns_transaction_process_dnssec (resolved-dns-transaction.c:976)
==463== by 0x4378C1: dns_transaction_process_reply (resolved-dns-transaction.c:1387)
==463== by 0x437CE9: on_dns_packet (resolved-dns-transaction.c:1444)
==463== by 0x4B2DC9B: source_dispatch (sd-event.c:3512)
==463== by 0x4B2FB1F: sd_event_dispatch (sd-event.c:4077)
==463== by 0x4B2FFFA: sd_event_run (sd-event.c:4138)
==463== by 0x4B301D6: sd_event_loop (sd-event.c:4159)
==463== by 0x464A24: run (resolved.c:92)
==463== by 0x464B3C: main (resolved.c:99)
==463== Address 0x5f409d0 is 32 bytes inside a block of size 72 free'd
==463== at 0x48410E4: free (vg_replace_malloc.c:755)
==463== by 0x418EDF: mfree (alloc-util.h:48)
==463== by 0x4197E8: dns_query_candidate_free (resolved-dns-query.c:67)
==463== by 0x4198B7: dns_query_candidate_unref (resolved-dns-query.c:70)
==463== by 0x41A2E3: dns_query_unref_candidates (resolved-dns-query.c:337)
==463== by 0x41C5FE: dns_query_cname_redirect (resolved-dns-query.c:1028)
==463== by 0x41CA04: dns_query_process_cname_one (resolved-dns-query.c:1128)
==463== by 0x41CA80: dns_query_process_cname_many (resolved-dns-query.c:1157)
==463== by 0x40C0BD: bus_method_resolve_hostname_complete (resolved-bus.c:198)
==463== by 0x41B312: dns_query_complete (resolved-dns-query.c:562)
==463== by 0x41C1AC: dns_query_accept (resolved-dns-query.c:922)
==463== by 0x41C2C4: dns_query_ready (resolved-dns-query.c:955)
==463== by 0x41A162: dns_query_candidate_notify (resolved-dns-query.c:314)
==463== by 0x434BD6: dns_transaction_complete (resolved-dns-transaction.c:437)
==463== by 0x438995: dns_transaction_prepare (resolved-dns-transaction.c:1728)
==463== by 0x43921D: dns_transaction_go (resolved-dns-transaction.c:1928)
==463== by 0x419C7C: dns_query_candidate_go (resolved-dns-query.c:163)
==463== by 0x41A143: dns_query_candidate_notify (resolved-dns-query.c:304)
==463== by 0x434BD6: dns_transaction_complete (resolved-dns-transaction.c:437)
==463== by 0x436A0F: dns_transaction_process_dnssec (resolved-dns-transaction.c:976)
==463== by 0x4378C1: dns_transaction_process_reply (resolved-dns-transaction.c:1387)
==463== by 0x437CE9: on_dns_packet (resolved-dns-transaction.c:1444)
==463== by 0x4B2DC9B: source_dispatch (sd-event.c:3512)
==463== by 0x4B2FB1F: sd_event_dispatch (sd-event.c:4077)
==463== by 0x4B2FFFA: sd_event_run (sd-event.c:4138)
==463== by 0x4B301D6: sd_event_loop (sd-event.c:4159)
==463== by 0x464A24: run (resolved.c:92)
==463== by 0x464B3C: main (resolved.c:99)
==463== Block was alloc'd at
==463== at 0x483E86F: malloc (vg_replace_malloc.c:380)
==463== by 0x418F81: malloc_multiply (alloc-util.h:96)
==463== by 0x419378: dns_query_candidate_new (resolved-dns-query.c:23)
==463== by 0x41B42C: dns_query_add_candidate (resolved-dns-query.c:582)
==463== by 0x41BB7A: dns_query_go (resolved-dns-query.c:762)
==463== by 0x40CE3A: bus_method_resolve_hostname (resolved-bus.c:464)
==463== by 0x4A84B86: method_callbacks_run (bus-objects.c:414)
==463== by 0x4A87961: object_find_and_run (bus-objects.c:1323)
==463== by 0x4A87FEE: bus_process_object (bus-objects.c:1443)
==463== by 0x4AA3434: process_message (sd-bus.c:2964)
==463== by 0x4AA3623: process_running (sd-bus.c:3006)
==463== by 0x4AA4110: bus_process_internal (sd-bus.c:3226)
==463== by 0x4AA41EF: sd_bus_process (sd-bus.c:3253)
==463== by 0x4AA5343: io_callback (sd-bus.c:3604)
==463== by 0x4B2DC9B: source_dispatch (sd-event.c:3512)
==463== by 0x4B2FB1F: sd_event_dispatch (sd-event.c:4077)
==463== by 0x4B2FFFA: sd_event_run (sd-event.c:4138)
==463== by 0x4B301D6: sd_event_loop (sd-event.c:4159)
==463== by 0x464A24: run (resolved.c:92)
==463== by 0x464B3C: main (resolved.c:99)
Fixes#19376.
We obviously have lots of those, so even small savings add up.
Bitfields are dropped because they don't give any memory savings due to
alignment requirements (but would still require more complex to access).
/* size: 184, cachelines: 3, members: 28 */
/* sum members: 172, holes: 1, sum holes: 4 */
/* sum bitfield members: 4 bits (0 bytes) */
/* padding: 7 */
/* bit_padding: 4 bits */
↓
/* size: 176, cachelines: 3, members: 28 */
The structure is rearranged to have less holes. Also fields in the union
are rearranged not to have holes (though most variants of the union still
have some padding at the end).
The full size does not decrease a lot, but the compiler should be able to
copy less bytes when it knows the specific type of the union.
Bitfields are dropped because they don't give any memory savings due to
alignment requirements (but would still require more complex to access).
The change from the this and previous commit:
/* size: 128, cachelines: 2, members: 13 */
/* sum members: 112, holes: 3, sum holes: 15 */
/* sum bitfield members: 2 bits, bit holes: 1, sum bit holes: 6 bits */
↓
/* size: 112, cachelines: 2, members: 13 */
/* sum members: 108, holes: 1, sum holes: 4 */
Change from the last three commits:
/* size: 312, cachelines: 5, members: 46 */
/* sum members: 296, holes: 5, sum holes: 16 */
↓
/* size: 288, cachelines: 5, members: 46 */
/* sum members: 286, holes: 1, sum holes: 1 */
It's not a big difference, but we might have quite a few queries in flight,
so let' make this a bit more efficient.
Apparently CAN links will show up in rtnetlink with very low MTUs. We
shouldn't consider them relevant if no IP is spoken over them, since
these MTUs are irrelevant for us then.
Hence, let's check if there's an address assigned to the link before
considering its MTU.
As additional safety net filter out MTUs smaller than the minimum DNS
packet size, too.
Finally, in case we don't find any suitable interface MTU, let's default
to 1500 as the generic Ethernet MTU.
Fixes: #19396
We usually call specifier_printf() and then check the validity of
the result. In many cases, validity checkers, e.g. path_is_valid(),
refuse too long strings. This makes specifier_printf() refuse such
long results earlier.
Moreover, unit_full_string() and description field in sysuser now
refuse results longer than LONG_LINE_MAX. config_parse() already
refuses the line longer than LONG_LINE_MAX. Hence, it should be ok
to set the same value as the maximum length of the resolved string.
During an update of RRs, the records of each DNS-SD service are
replaced with new ones. However the old RRs can only be removed from
the mDNS scopes as long as they remain accessible from the DnssdService
structures, otherwise they remain stuck there.
Therefore the removal must take place before the update.
With some versions of the compiler, the _cleanup_ attr makes it think
the variable might be freed/closed when uninitialized, even though it
cannot happen. The added cost is small enough to be worth the benefit,
and optimized builds will help reduce it even further.
The issue was introduced in the refactoring in 775ae35403.
We would pass an initialized value to a helper function. We would only *use*
it if it was initialized. But the mere passing of an unitialized variable is
UB, so let's not do that. This silences a gcc warning.
RFC 6762 defines the top bit in RRs to mean cache flush (section 10.2),
and the top bit in questions to mean that a unicast reply is wanted
(section 5.4).
dns_packet_read_key() is used for parsing both questions and RRs.
When called from dns_packet_extract_question(), the top bit being set
should not result in the packet being rejected as invalid.
Fixes https://github.com/systemd/systemd/issues/17973
Check the return code from gcrypt's functions. In some
cases just log, as it shoulnd't really happen.
Fixes various Coverity issues:
CID #1444702
CID #1444704
CID #1444706
CID #1444711
CID #1444712
CID #1444713
let's make sure we set the "aa" bit in the stub only if we answer with
fully authoritative data. For this ensure:
1. Either all data is synthetic, including all CNAME/DNAME redirects
2. Or all data comes from the local trust anchor or the local zones
(i.e. not the network or the cache)
Follow-up for 4ad017cda5
