Introduce a _very_ simple DNS server using our internal DNS-related
code, that responds to queries with specifically crafted packets, to
cover scenarios that are difficult to reproduce with well-behaving DNS
servers.
Also, hide the test DNS server behind Knot using the dnsproxy module, so
we don't have to switch DNS servers during tests.
Otherwise we might occasionally hit the start rate limit, as we restart
the service a bunch of times:
[ 3702.280886] testsuite-75.sh[1135]: + tee /tmp/tmp.wUL8bkJwrt
[ 3702.283684] testsuite-75.sh[1135]: {}
[ 3702.284254] testsuite-75.sh[46]: + restart_resolved
[ 3702.284302] testsuite-75.sh[46]: + systemctl stop systemd-resolved.service
[ 3702.310678] testsuite-75.sh[1140]: + systemctl is-failed systemd-resolved.service
[ 3702.316766] testsuite-75.sh[1141]: inactive
[ 3702.316998] testsuite-75.sh[46]: + systemctl start systemd-resolved.service
[ 3702.322315] systemd[1]: systemd-resolved.service: Start request repeated too quickly.
[ 3702.322343] systemd[1]: systemd-resolved.service: Failed with result 'start-limit-hit'.
[ 3702.322609] systemd[1]: Failed to start systemd-resolved.service - Network Name Resolution.
[ 3702.323619] systemctl[1142]: Job for systemd-resolved.service failed.
[ 3702.323839] systemctl[1142]: See "systemctl status systemd-resolved.service" and "journalctl -xeu systemd-resolved.service" for details.
[ 3702.325035] systemd[1]: testsuite-75.service: Failed with result 'exit-code'.
[ 3702.325391] systemd[1]: Failed to start testsuite-75.service - Tests for systemd-resolved.
Follow-up for b1384db11b and 6ef512c0bb.
So the coverage-related drop-in [0] can kick in to avoid errors with
DynamicUser=true. Also, to not make the test confusing with this change,
replace "nft-test" with "test-nft" everywhere.
[0] See test/README.testsuite, section "Code coverage"
From RFC 9476:
Because names beneath .alt are in an alternative namespace, they have no
significance in the regular DNS context. DNS stub and recursive
resolvers do not need to look them up in the DNS context.
See: https://datatracker.ietf.org/doc/html/rfc9476#name-the-alt-namespace
In etc_hosts_lookup_by_address(), make sure the canonical name of the given
address is returned first in the list of names that address resolves to.
Resolves: #25088
serve stale feature to keep the DNS resource records beyond TTL to return them as stale records in case of upstream server is not reachable or returns negative response.
SD_RESOLVED_NO_STALE flag has been added to disable serving stale records via dbus.
added serve stale test cases to TEST-75-RESOLVED
Fixes: #21815
Without enabling itx, there's no symlink to the org.freedesktop.resolve1
dbus service, so there exists a tiny window in which the sequence of
`systemctl start` and `systemctl service-log-level` commands might fail:
[ 1127.615151] H systemd[1]: Started Network Name Resolution.
[ 1127.617768] H testsuite-75.sh[34]: + systemctl service-log-level systemd-resolved.service debug
[ 1127.621251] H dbus-daemon[54]: [system] Activating via systemd: service name='org.freedesktop.resolve1' unit='dbus-org.freedesktop.resolve1.service' requested by ':1.24' (uid=0 pid=119 comm="systemctl service-log-level systemd-resolved>
[ 1127.621336] H systemd[1]: dbus-org.freedesktop.resolve1.service: Failed to load configuration: No such file or directory
[ 1127.621364] H systemd[1]: dbus-org.freedesktop.resolve1.service: Trying to enqueue job dbus-org.freedesktop.resolve1.service/start/replace
[ 1127.621395] H systemd[1]: D-Bus activation failed for dbus-org.freedesktop.resolve1.service: Unit dbus-org.freedesktop.resolve1.service not found.
[ 1127.621965] H dbus-daemon[54]: [system] Activation via systemd failed for unit 'dbus-org.freedesktop.resolve1.service': Unit dbus-org.freedesktop.resolve1.service not found.
[ 1127.622046] H systemd[1]: systemd-resolved.service: D-Bus name org.freedesktop.resolve1 now owned by :1.25
[ 1127.622130] H systemctl[119]: Failed to set log level of org.freedesktop.resolve1 to debug: Unit dbus-org.freedesktop.resolve1.service not found.
Spotted in a couple of recent Ubuntu CI runs.
This reverts commit 5dd34c2604.
`resolvectl monitor` sends notify event, and systemd-run wait for the
service being in active state. Hence, the loop is not necessary.
Let's remove some sleep loops, and instead:
1. Use Type=notify to wait until "resolvectl monitor" successfully
installed its monitor, so that we know that queries enqueued later
will definitely be seen.
2. Use "grep -m1" to watch "journalctl -f" output to wait precisely for
the RR data we want to see, and immediately exit.
This shortens code quite a bit, and should make it more robust.
Let's parse the resolved JSON notifications via `jq` and check them in a
bit more "controlled" manner - e.g. until now the `grep` was checking just
a one gigantic JSON string, as all received notifications via the
varlink socket are terminated by a NUL character, not a newline.
Also, as the notification delivery is asynchronous, retry the check
a couple of times if it fails (spotted in C8S jobs):
```
[ 2891.935879] testsuite-75.sh[36]: + : '--- nss-resolve/nss-myhostname tests'
[ 2891.935988] testsuite-75.sh[36]: + run getent -s resolve hosts ns1.unsigned.test
[ 2891.936542] testsuite-75.sh[177]: + getent -s resolve hosts ns1.unsigned.test
[ 2891.937499] testsuite-75.sh[178]: + tee /tmp/tmp.pqjNvbQ2eS
[ 2891.939977] testsuite-75.sh[178]: 10.0.0.1 ns1.unsigned.test
[ 2891.940258] testsuite-75.sh[36]: + grep -qE '^10\.0\.0\.1\s+ns1\.unsigned\.test' /tmp/tmp.pqjNvbQ2eS
[ 2891.942235] testsuite-75.sh[189]: + grep -qF '[10,0,0,1]'
[ 2891.942577] testsuite-75.sh[188]: + grep -aF ns1.unsigned.test /tmp/notifications.txt
[ 2891.943978] systemd[1]: testsuite-75.service: Child 36 belongs to testsuite-75.service.
[ 2891.944112] systemd[1]: testsuite-75.service: Main process exited, code=exited, status=1/FAILURE
[ 2891.944215] systemd[1]: testsuite-75.service: Failed with result 'exit-code'.
```
* The new varlink interface exposes a method to subscribe to DNS
resolutions on the system. The socket permissions are open for owner and
group only.
* Notifications are sent to subscriber(s), if any, after successful
resolution of A and AAAA records.
This feature could be used by applications for auditing/logging services
downstream of the resolver. It could also be used to asynchronously
update the firewall. For example, a system that has a tightly configured
firewall could open up connections selectively to known good hosts based
on a known allow-list of hostnames. Of course, updating the firewall
asynchronously will require other design considerations (such as
queueing packets in the user space while a verdict is made).
See also:
https://lists.freedesktop.org/archives/systemd-devel/2022-August/048202.htmlhttps://lists.freedesktop.org/archives/systemd-devel/2022-February/047441.html
delv on Ubuntu defaults to /etc/bind/bind.keys instead of /etc/bind.keys
when reading trust anchors, so let's create a symlink to make the test
work there as well.
Resolves: #24453
Frantisek Sumsal
Yu Watanabe
Bertrand Jacquin
Topi Miettinen
Kiran Vemula
Kiran Vemula
Dmitry V. Levin
Lennart Poettering
Luca Boccassi
Suraj Krishnan