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Fix rare "Internal error in cache" messages.

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Fix error created in 1ce1c6beae

Many thanks to Hartmut Birr for finding the bug and bisecting to
the guilty commit.

The breaking commit creates cache entries which have F_NXDOMAIN
set but none of F_IPV4, F_IPV6 or F_SRV. If cache_scan_free() is called
to delete such an entry it will fail to do so.

If the cache has no free slots and the least-recently-used slot is such
an entry, then a new insertion will attempt to make space by calling
cache_scan_free(), which will fail when it should be impossible and
trigger the internal error.
This commit is contained in:
Simon Kelley
2021-12-24 18:58:35 +00:00
parent 18b1d1424e
commit ea33a01303
1 changed files with 1 additions and 1 deletions
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2
src/cache.c
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@@ -413,7 +413,7 @@ static struct crec *cache_scan_free(char *name, union all_addr *addr, unsigned s
if ((crecp->flags & F_FORWARD) && hostname_isequal(cache_get_name(crecp), name)) if ((crecp->flags & F_FORWARD) && hostname_isequal(cache_get_name(crecp), name))
{ {
/* Don't delete DNSSEC in favour of a CNAME, they can co-exist */ /* Don't delete DNSSEC in favour of a CNAME, they can co-exist */
if ((flags & crecp->flags & (F_IPV4 | F_IPV6 | F_SRV)) || if ((flags & crecp->flags & (F_IPV4 | F_IPV6 | F_SRV | F_NXDOMAIN)) ||
(((crecp->flags | flags) & F_CNAME) && !(crecp->flags & (F_DNSKEY | F_DS)))) (((crecp->flags | flags) & F_CNAME) && !(crecp->flags & (F_DNSKEY | F_DS))))
{ {
if (crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) if (crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG))