tools/dhcpv6-pd_ia: fix: Add explicit subnet id

[xnumad]

Adjust prefix delegation config for Kea 2.6.0

Contribution description

https://github.com/isc-projects/kea/blob/master/ChangeLog:

Kea 2.6.0 (stable) released on May 29, 2024

[...]

2232.	[func]*		fdupont
	Auto-generated subnet identifiers are no longer supported.
	Configurations that contain subnets without explicit subnet
	identifiers (i.e. without an "id" entry) will now be rejected.
	(Gitlab #2961)

Testing procedure

(for reproducability: sudo killall kea-dhcp6)
cd examples/gnrc_border_router/
sudo PREFIX_CONF=dhcpv6 IPV6_PREFIX=2001:db8::/64 make all term
While the application is running, observe that no kea actually runs: ps -aux | grep kea

Kea throws an error that the "id" entry is missing and exits. The error is however silenced by the python script.
Having no DHCP server, the gnrc_border_router (6LBR) application cannot contact any such server and therefore has no prefix.

Finding the error

Finding the error

Find out how kea is started.

Apply this change (patch):

diff --git a/dist/tools/dhcpv6-pd_ia/base.py b/dist/tools/dhcpv6-pd_ia/base.py
index b68f2d6438..2a93197e96 100644
--- a/dist/tools/dhcpv6-pd_ia/base.py
+++ b/dist/tools/dhcpv6-pd_ia/base.py
@@ -200,4 +200,5 @@ class DHCPv6Server(metaclass=_SingletonMeta):
             # Start the daemon
             self.daemonize()
         self.pre_run()
+        print("command is", self.command)
         subprocess.run(self.command)

sudo PREFIX_CONF=dhcpv6 IPV6_PREFIX=2001:db8::/64 make all term

command is ['kea-dhcp6', '-c', '/tmp/tmpsabotu4_']

Start kea manually

sudo kea-dhcp6 -c /tmp/tmpsabotu4_

2024-07-05 10:25:04.238 ERROR [kea-dhcp6.dhcp6/79049.140215599218944] DHCP6_CONFIG_LOAD_FAIL configuration error using file: /tmp/tmpsabotu4_, reason: Unable to open file /tmp/tmpsabotu4_
2024-07-05 10:25:04.238 ERROR [kea-dhcp6.dhcp6/79049.140215599218944] DHCP6_INIT_FAIL failed to initialize Kea server: configuration error using file '/tmp/tmpsabotu4_': Unable to open file /tmp/tmpsabotu4_

Keep config file

Make the script not delete the file after kea exits, so that the file can be inspected for debugging purposes.
Apply this change (patch):

diff --git a/dist/tools/dhcpv6-pd_ia/kea.py b/dist/tools/dhcpv6-pd_ia/kea.py
index d9bb6f1d93..567f0ed7ed 100644
--- a/dist/tools/dhcpv6-pd_ia/kea.py
+++ b/dist/tools/dhcpv6-pd_ia/kea.py
@@ -76,7 +89,7 @@ class KeaConfig(object):
 
     def __str__(self):
         if self.config_file is None:
-            self.config_file = tempfile.NamedTemporaryFile(mode="w")
+            self.config_file = tempfile.NamedTemporaryFile(mode="w", delete=False)
         self._dump_json()
         return self.config_file.name

Retry

sudo PREFIX_CONF=dhcpv6 IPV6_PREFIX=2001:db8::/64 make all term

command is ['kea-dhcp6', '-c', '/tmp/tmpq8boziok']

Still: While the application is running, observe that no kea actually runs: ps -aux | grep kea

Run kea manually: sudo kea-dhcp6 -c /tmp/tmpq8boziok

...
2024-06-17 19:07:30.498 ERROR [kea-dhcp6.dhcp6/157063.140048319762688] DHCP6_PARSER_FAIL failed to create or run parser for configuration element subnet6: subnet configuration failed: missing parameter 'id' (/tmp/tmpq8boziok:1:206)
2024-06-17 19:07:30.498 ERROR [kea-dhcp6.dhcp6/157063.140048319762688] DHCP6_CONFIG_LOAD_FAIL configuration error using file: /tmp/tmpq8boziok, reason: subnet configuration failed: missing parameter 'id' (/tmp/tmpq8boziok:1:206)
2024-06-17 19:07:30.498 ERROR [kea-dhcp6.dhcp6/157063.140048319762688] DHCP6_INIT_FAIL failed to initialize Kea server: configuration error using file '/tmp/tmpq8boziok': subnet configuration failed: missing parameter 'id' (/tmp/tmpq8boziok:1:206)

https://kea.readthedocs.io/en/kea-2.6.0/arm/dhcp6-srv.html#ipv6-subnet-identifier

[riot-ci]

Murdock results

✔️ PASSED

96a91ba tools/dhcpv6-pd_ia: fix: Add explicit subnet id

Success	Failures	Total	Runtime
1	0	1	01m:15s

Artifacts

• Documentation preview

[mguetschow]

Thanks for finding and fixing!