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David Nichols
ad9208358e
--no-dhcpv4-interface=IFACE is documented to disable only DHCPv4 on an interface,
leaving DHCPv6/RA untouched. That's exactly how it's implemented in the option parser
(option.c, LOPT_NO_DHCP4 case): the exclusion entry is tagged INAME_4 only, with INAME_6
explicitly cleared. The two general-purpose exclusion checks that consult this list also
respect the split correctly:
- dhcp6.c:184-186 (regular DHCPv6 request handling)
- radv.c:187-189 and radv.c:836-839 (RA sending)
All three do:
if (tmp->name && (tmp->flags & INAME_6) && wildcard_match(tmp->name, iface))
But construct_worker() in dhcp6.c — the callback used to build a context from a
"constructor:IFACE" template range (dhcp-range=::,constructor:IFACE,ra-only,64,...) —
checks the same list without the flag test:
src/dhcp6.c, lines 700-702 (2.93; same in 2.90):
for (tmp = daemon->dhcp_except; tmp; tmp = tmp->next)
if (tmp->name && wildcard_match(tmp->name, ifrn_name))
return 1;
Because this only tests tmp->name and ignores tmp->flags, an interface added to
dhcp_except via --no-dhcpv4-interface (INAME_4 only, INAME_6 cleared) is excluded here
regardless — silently killing RA/DHCPv6 on that interface too, contradicting both the
documentation and the behaviour of every other exclusion check in the codebase.