On 9/15/17 2:12 PM, Jason Lixfeld wrote:
> Hello,
>
> I was troubleshooting an issue with host reservations via flex-id and
> postgresql.
>
> I tracked it down to a difference in how the database was storing
> identifier_value, vs. how the identifier_expression is configured in the kea
> config file.
>
> The kea debug shows the generated flex-id:
>
> 2017-09-15 13:32:01.182 DEBUG [kea-dhcp4.packets/631] DHCP4_FLEX_ID flexible
> identifier generated for incoming packet:
> flex-id=010972677730312E6C616200040C370201
>
> The kea config identifier_expression is like so:
>
> "hooks-libraries": [
> {
> "library": "/usr/local/lib/hooks/libdhcp_flex_id.so",
> "parameters":
> {
> "identifier-expression":
> "concat(relay4[2].hex,relay4[1].hex)"
> }
> }
> ],
>
> I set the identifier_value per the how-to
> (https://kea.isc.org/wiki/HostReservationsHowTo) to match what the kea debug
> generated for the flex-id:
>
> …
> …
> kea=# \set identifier_value ‘010972677730312e6c616200040c370201'
> …
> …
>
> When I noticed that the reservation was not working, I looked at the postgres
> query that Kea was making, and it appears as though $3 is prepended with \x :
>
> 2017-09-15 13:32:01.189 EDT [726] kea@kea LOG: execute
> get_host_subid4_dhcpid: SELECT h.host_id, h.dhcp_identifier,
> h.dhcp_identifier_type, h.dhcp4_subnet_id, h.dhcp6_subnet_id,
> h.ipv4_address, h.hostname, h.dhcp4_client_classes, h.dhcp6_client_classes,
> h.dhcp4_next_server, h.dhcp4_server_hostname, h.dhcp4_boot_file_name,
> o.option_id, o.code, o.value, o.formatted_value, o.space, o.persistent FROM
> hosts AS h LEFT JOIN dhcp4_options AS o ON h.host_id = o.host_id WHERE
> h.dhcp4_subnet_id = $1 AND h.dhcp_identifier_type = $2 AND
> h.dhcp_identifier = $3 ORDER BY h.host_id, o.option_id
> 2017-09-15 13:32:01.189 EDT [726] kea@kea DETAIL: parameters: $1 = '1', $2 =
> '4', $3 = '\x010972677730312e6c616200040c370201’
>
> Making that query directly of course fails, which is where the issue lies:
>
> SELECT h.host_id, h.dhcp_identifier, h.dhcp_identifier_type,
> h.dhcp4_subnet_id, h.dhcp6_subnet_id, h.ipv4_address, h.hostname,
> h.dhcp4_client_classes, h.dhcp6_client_classes, h.dhcp4_next_server,
> h.dhcp4_server_hostname, h.dhcp4_boot_file_name, o.option_id, o.code,
> o.value, o.formatted_value, o.space, o.persistent FROM hosts AS h LEFT JOIN
> dhcp4_options AS o ON h.host_id = o.host_id WHERE h.dhcp4_subnet_id = '1' AND
> h.dhcp_identifier_type = '4' AND h.dhcp_identifier =
> '\x010972677730312e6c616200040c370201' ORDER BY h.host_id, o.option_id;
>
> host_id | dhcp_identifier | dhcp_identifier_type | dhcp4_subnet_id |
> dhcp6_subnet_id | ipv4_address | hostname | dhcp4_client_classes |
> dhcp6_client_classes | dhcp4_next_server | dhcp4_server_hostname |
> dhcp4_boot_file_name | option_id | code | value | formatted_value | space |
> persistent
> ---------+-----------------+----------------------+-----------------+-----------------+--------------+----------+----------------------+----------------------+-------------------+-----------------------+----------------------+-----------+------+-------+-----------------+-------+------------
> (0 rows)
>
> If I remove the leading \x from the query, the expected results are presented:
>
> SELECT h.host_id, h.dhcp_identifier, h.dhcp_identifier_type,
> h.dhcp4_subnet_id, h.dhcp6_subnet_id, h.ipv4_address, h.hostname,
> h.dhcp4_client_classes, h.dhcp6_client_classes, h.dhcp4_next_server,
> h.dhcp4_server_hostname, h.dhcp4_boot_file_name, o.option_id, o.code,
> o.value, o.formatted_value, o.space, o.persistent FROM hosts AS h LEFT JOIN
> dhcp4_options AS o ON h.host_id = o.host_id WHERE h.dhcp4_subnet_id = '1' AND
> h.dhcp_identifier_type = '4' AND h.dhcp_identifier =
> '010972677730312e6c616200040c370201' ORDER BY h.host_id, o.option_id;
>
> host_id | dhcp_identifier
> | dhcp_identifier_type | dhcp4_subnet_id | dhcp6_subnet_id | ipv4_address
> | hostname | dhcp4_client_classes | dhcp6_client_classes | dhcp4_next_server
> | dhcp4_server_hostname | dhcp4_boot_file_name | option_id | code | value |
> formatted_value | space | persistent
> ---------+------------------------------------------------------------------------+----------------------+-----------------+-----------------+--------------+----------+----------------------+----------------------+-------------------+-----------------------+----------------------+-----------+------+-------+-----------------+-------+------------
> 6 |
> \x30313039373236373737333033313265366336313632303030343063333730323031 |
> 4 | 1 | | 171966277 |
> | | | |
> | bootfile.efi | | | |
> | |
> (1 row)
>
> Manually decoding the dhcp_identifier shows the non-prepended value:
>
> kea=# select
> convert_from('\x30313039373236373737333033313265366336313632303030343063333730323031',
> 'UTF-8');
> convert_from
> ------------------------------------
> 010972677730312e6c616200040c370201
> (1 row)
>
> kea=#
>
> So my question is did I misinterpret the instructions (either by cluelessness
> or oversight) when setting this up, or is this a bug?
>
> Thanks!
> _______________________________________________
> Kea-users mailing list
> [email protected]
> https://lists.isc.org/mailman/listinfo/kea-users
Hello Jason:
We're looking into this for you. In the meantime you could try
prepending '\x' onto the identifier value you inserted.
Regards,
Thomas Markwalder
ISC Software Engineering
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