Sets from Jarl: sets holding the addresses of names in Jarl

A set can take its addresses from Jarl: every A and AAAA record of its
names (NAME@VIEW), CNAMEs followed within Jarl's zones in the same view.
housecarld reads them every jarl.refresh and after each change, keeps
only the addresses within the zones and networks the set allows, and
keeps what it last read (saved in the database and the boot ruleset)
while Jarl can't be reached. A change of the addresses applies the
ruleset again without a history entry and is audited (set.jarl).

hc set add --jarl --within, hc set jarl; the kind "from Jarl" and
Addresses… on the Sets page; GET /sets/{name}/jarl and /jarl/refresh;
validation codes set_jarl_*, status warnings jarl_*; docs/jarl.md.
e2e phase with scripts/fakejarl.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/validation.md

@@ -53,9 +53,14 @@ are unique per kind, ignoring case.
 |---|---|---|
 | `set_name_reserved` | error | a set name starting with `meter_`, `conn_`, `quota_`, `stats_` or `ban_`: Housecarl's own sets (rate limits, quotas, statistics, ban lists) use those |
 | `set_entry` | error | an entry that isn't an address, prefix (without host bits) or range |
-| `set_empty` | warning | a set (not dynamic) with no entries: rules using it match nothing |
+| `set_empty` | warning | a set (not dynamic, not from Jarl) with no entries: rules using it match nothing |
 | `set_dynamic_entries` | error | configured entries on a dynamic set: its entries come at run time |
 | `set_timeout` | error | a timeout on a set that isn't dynamic, or under a second |
+| `set_jarl_entries` | error | configured entries on a set from Jarl: its addresses are its names' ([jarl.md](jarl.md#sets-from-jarl)) |
+| `set_jarl_dynamic` | error | a set both dynamic and from Jarl |
+| `set_jarl_names` | error | a set from Jarl without names, with one that isn't a DNS name (a wildcard, say) or a bad view, or with a name twice |
+| `set_jarl_within` | error | a set from Jarl without `within`, or with an entry there that is neither a zone nor an address, network or range |
+| `set_jarl_anywhere` | warning | a set from Jarl `within 0.0.0.0/0` or `::/0`: any address may come in, so whoever changes the names in Jarl decides what it holds |
 | `service_empty` | error | a service with no entries |
 | `service_entry` | error | an entry that isn't `PROTO/PORTS` (`tcp`, `udp`, `sctp`; a port or range) or `icmp/TYPE`, `icmpv6/TYPE` with a type nftables knows |
 
@@ -134,6 +139,10 @@ configuration: the dashboard and `hc status` show them.
 | `conntrack_full` | warning, *host* | the connection tracking table is over 80% full; once it is full, the kernel drops new connections. Raise `net.netfilter.nf_conntrack_max`, or find what opens so many ([stats.md](stats.md#warnings)) |
 | `takeover_pending` | warning, *host* | the table you imported from is still in force beside Housecarl's, so a packet must get past both; `hc takeover TABLE` deletes it once Housecarl's rules are right |
 | `shadow_unprotected` | warning, *host* | shadow mode, and no other table has a filter chain on the input hook: Housecarl's ruleset blocks nothing, and nothing else protects the machine. Load your firewall, or leave shadow mode ([shadow.md](shadow.md)) |
+| `jarl_name` | warning, *host* | a set from Jarl has a name that gives no addresses, and why: no A, AAAA or CNAME record, a wildcard only, a CNAME out of Jarl's zones or in a loop, below a delegation, a zone Jarl doesn't hold the records of, or in more than one view without one named ([jarl.md](jarl.md#what-a-name-gives)) |
+| `jarl_outside` | warning, *host* | an address a name has in Jarl is left out of its set: it isn't within the set's zones and networks ([jarl.md](jarl.md#within)) |
+| `jarl_unreachable` | warning, *host* | reading Jarl failed (unreachable, the token refused…), for every name or one; the sets keep the addresses they had ([jarl.md](jarl.md#when-jarl-cant-be-reached)) |
+| `jarl_not_configured` | warning, *host* | sets from Jarl, but no `jarl.server` in `housecarl.yaml`: they keep the addresses they last had |
 | `shadow_raw_left_out` | warning, *host* | shadow mode leaves this raw rule out: it does more to packets than accept, drop or reject (NAT, setting a mark or field, a jump, a verdict map…). Its hits aren't counted, and the rules after it see what it would have taken ([shadow.md](shadow.md#what-changes-in-the-ruleset)) |
 
 In shadow mode `nftables_service` and `takeover_pending` aren't raised: