Let's replace usage of fputc_unlocked() and friends by __fsetlocking(f,
FSETLOCKING_BYCALLER). This turns off locking for the entire FILE*,
instead of doing individual per-call decision whether to use normal
calls or _unlocked() calls.
This has various benefits:
1. It's easier to read and easier not to forget
2. It's more comprehensive, as fprintf() and friends are covered too
(as these functions have no _unlocked() counterpart)
3. Philosophically, it's a bit more correct, because it's more a
property of the file handle really whether we ever pass it on to another
thread, not of the operations we then apply to it.
This patch reworks all pieces of codes that so far used fxyz_unlocked()
calls to use __fsetlocking() instead. It also reworks all places that
use open_memstream(), i.e. use stdio FILE* for string manipulations.
Note that this in some way a revert of 4b61c87511.
RFC 8080 describes how to use EdDSA keys and signatures in DNSSEC. It
uses the curves Ed25519 and Ed448. Libgcrypt 1.8.1 does not support
Ed448, so only the Ed25519 is supported at the moment. Once Libgcrypt
supports Ed448, support for it can be trivially added to resolve.
Currently, we accept SERVFAIL after downgrading fully, cache it and move
on. Let's extend this a bit: after downgrading fully, if the SERVFAIL
logic continues to be an issue, then use a different DNS server if there
are any.
Fixes: #7147
This makes sure that a classic DNS scope that has no DNS servers
assigned is never considered for routing requests to even if it has
matching search/routing domains associated.
This is inspired by #7544, where lookup requests are refused since a
scope with no DNS server is configured. This change does not deliver
what the reporter intended, but is generally useful in general, as it
makes us mor robust to misconfiguration.
The user might replace a foreign /etc/resolv.conf with a symlink to one
of ours between the time we did stat() and open the file. Hence, let's
check the fstat() data right after opening the file, a second time.
It might happen that a DNS-SD service doesn't include local host's
name in its RR keys and still conflicts with a remote service.
In this case try to resolve the conflict by changing name for
this particular service.
As discussed in RFC 6762, Section 8.2 a race condition may
happen when two hosts are probing for the same name simultaniously.
Detect and handle such race conditions.
According to RFC 6762 Section 8.2 "Simultaneous Probe Tiebreaking"
probing queries' Authority Section is populated with proposed
resource records in order to resolve possible race conditions.
From RFC 6762, Section 10.2
"They (the rules about when to set the cache-flush bit) apply to
startup announcements as described in Section 8.3, "Announcing",
and to responses generated as a result of receiving query messages."
So, set the cache-flush bit for mDNS answers except for DNS-SD
service enumerattion PTRs described in RFC 6763, Section 4.1.
According to p5.3 of RFC6762 (Multicast DNS) one mDNS query message
can contain more than one question sections.
Generate answers for all found questions and put them to a reply
message.
This might very well happen due to races between joining multicast
groups and network configuration and such, let's not complain, but just
drop the messages at debug level.
Fixes: #7527
So far I avoided adding license headers to meson files, but they are pretty
big and important and should carry license headers like everything else.
I added my own copyright, even though other people modified those files too.
But this is mostly symbolic, so I hope that's OK.
This creates a second private resolve.conf file which lists the stub resolver
and the resolved acquired search domains.
This runtime file should be used as a symlink target for /etc/resolv.conf such
that non-nss based applications can resolve search domains.
Fixes: #7009
This adds "systemd-resolve --reset-server-features" for explicitly
forgetting what we learnt. This might be useful for debugging
purposes, and to force systemd-resolved to restart its learning logic
for all DNS servers.
When the network configuration changes we should relearn everything
there is to know about the configured DNS servers, because we might talk
to the same addresses, but there might be different servers behind them.
When we a reply message gets longer than the client supports we need to
truncate the response and set the TC bit, and we already do that.
However, we are not supposed to send incomplete RRs in that case, but
instead truncate right at a record boundary. Do that.
This fixes the "Message parser reports malformed message packet."
warning the venerable "host" tool outputs when a very large response is
requested.
See: #6520
