The goal here is to help new or infrequent users figure out the most
basic ways to use dig.
Notes on the choice of examples:
* I wrote examples that users can copy and paste exactly as is, without
having to come up with an appropriate IP address or domain name to use.
The one exception is the `dig -x` example which uses an IP from the
example range.
* `dig +noall +answer` here is because learning about `+noall +answer`
was lifechanging for me when I learned about it, I've heard from
others that they find it helpful too, and it's pretty hard to infer
from the man page as is that it might be useful
* I thought about adding `+trace` but left it out because 5 examples was
already starting to feel like a lot.
This is now duplicate as the default ports are already set in
isc_netmgr_create().
Merge branch 'ondrej/mr11569-followup-cleanup' into 'main'
See merge request isc-projects/bind9!11576
With the Python version bumped to 3.10 and the dependency situation cleared with !11415 it is now time to run linters and formatters on more parts of the Python code that was previously skipped or ignored.
Switch configuration of the various Python-adjacent tools to `pyproject.toml` to ensure that the same configuration is used in CI and locally.
See the individual commits for details on settings changed and linters added.
Tweaks to type checking and enabling more `ruff` lints will come in a subsequent MRs.
Prerequisites:
- bind9-qa!160.
- images!442
Merge branch 'stepan/python-tooling' into 'main'
See merge request isc-projects/bind9!11499
Add a pylint plugin that enforces:
- There is no bare `import dns` statement.
- All `dns.<module>` used are explicitly imported.
- There are no unused `dns.<module>` imports.
Fix all the imports to conform with this check.
In Python 3.10 strings don't support the | operator, so ruff doesn't
attempt to fix these. Quote the entire type specification to avoid the
typing.Optional import.
Alternatives I considered:
- leaving it as is (only use of Optional in the code base)
- using `from future import __annotations__` (replacing one import with
another one)
Importing pytest fixture trips up static analysis tools, so move
default_algorithm to conftest.py and use it instead of os.environ
accesses in various system tests.
For use outside test function, use Algorithm.default().
Cloning to a stable location allows clearer handling of paths when
calling scripts from CI jobs.
`unit:gcc:tarball` and `system:gcc:tarball` do `cd bind-*` in
`before_script` which lead to the `bind9-qa` directory ending up in
a different place in exactly these two jobs and that made reasoning
about paths in `.system_test_common` and `.unit_test_common` tricky.
Enable a socket option on the outgoing TCP sockets to allow faster selection of the source <address,port> tuple for different destination <address,port> tuples when nearing over 70-80% of the source port utilization.
Merge branch 'improve-selection-of-outgoing-TCP-port' into 'main'
See merge request isc-projects/bind9!11569
For Linux >= 6.8:
Since 2023, Linux has introduced a change to the IP_LOCAL_PORT_RANGE
socket option that eliminates the need for the random window
shifting (implemented as a fallback in the next commit).
By setting IP_LOCAL_PORT_RANGE option, we tell the kernel to use better
approach to the source port selection.
For Linux << 6.8:
This implement selecting port by random shifting range leveraging the
IP_LOCAL_PORT_RANGE socket option. The network manager is initialized
with the ephemeral port range (on startup and on reconfig) and then for
every outgoing TCP connection, we define a custom port range (1000
ports) and then randomly shift the custom range within the system range.
This helps the kernel to reduce the search space to the custom window
between <random_offset, random_offset + 1000>.
Reference:
https://blog.cloudflare.com/linux-transport-protocol-port-selection-performance/#kernel
Since 2015, Linux has introduced a new socket option to overcome TCP
limitations: When an application needs to force a source IP on an active
TCP socket it has to use bind(IP, port=x). As most applications do not
want to deal with already used ports, x is often set to 0, meaning the
kernel is in charge to find an available port. But kernel does not know
yet if this socket is going to be a listener or be connected. This
IP_BIND_ADDRESS_NO_PORT socket option ask the kernel to ignore the 0
port provided by application in bind(IP, port=0) and only remember the
given IP address. The port will be automatically chosen at connect()
time, in a way that allows sharing a source port as long as the 4-tuples
are unique.
Enable IP_BIND_ADDRESS_NO_PORT on the outgoing TCP sockets to overcome
this TCP limitation.
The function was already marked as never failing, always returning
ISC_R_SUCCESS, so there was a lot of dead code around checking whether
the result would be ISC_R_SUCCESS. This has been cleaned up.
An attacker controlling a malicious DNS server returns a DNAME record,
and the we stores a pointer to resp->foundname, frees the response
structure, then uses the dangling pointer in dns_name_fullcompare()
possibly causing invalid match. Only the `delv`is affected. This has
been fixed.
Closes#5728
Merge branch '5728-heap-uaf-in-bind9-dns_client_resolve-via-dname-response' into 'main'
See merge request isc-projects/bind9!11570
An attacker controlling a malicious DNS server returns a DNAME record,
and the we stores a pointer to resp->foundname, frees the response
structure, then uses the dangling pointer in dns_name_fullcompare()
possibly causing invalid match. Only the `delv`is affected. This has
been fixed.
Fix the `update-stable-tag` job, necessary for updating Read the Docs.
Merge branch 'andoni/fix-update-stable-branch-for-rtd-job' into 'main'
See merge request isc-projects/bind9!11559
If the source address is not available do not attempt
to retry over TCP otherwise clear the TSIG key from the
message prior to retrying.
Closes#5457
Merge branch '5457-remove-tcp-retry-in-notify-send-toaddr' into 'main'
See merge request isc-projects/bind9!10805
named was asserting when the notify source address was not available
and TSIG was being used. Check this scenario by adding a nameserver
to the zone which is configured to uses a non-existent source address
and a blackholed destination address and a TSIG using a server clause
for that destination address.
Prevent retrying the notify over TCP in case the source address is not
available or the source vs the destination address family mismatch or
when the destination address has been blackholed. Properly log the
hard notify failures.
When dns_request_create() fails in notify_send_toaddr() the TSIG key was
not cleared when retrying over TCP causing assertion failure. Set the
TSIG key to NULL in the dns_message to prevent the assertion failure.
RFC 7871 only defines family 1 (IPv4) and 2 (IPv6). Additionally
it requires FORMERR to be returned for all unknown families.
Merge branch 'marka-formerr-family-0' into 'main'
See merge request isc-projects/bind9!11563
