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MINOR: resolvers: use the runtime IPv6 status instead of boot time one

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On systems where the network is not reachable at boot time (certain HA
systems for example, or dynamically addressed test machines), we'll want
to be able to periodically revalidate the IPv6 reachability status. The
current code makes it complicated because it sets the config bits once
for all at boot time. This commit changes this so that the config bits
are not changed, but instead we rely on a static inline function that
relies on sock_inet6_seems_reachable for every test (really cheap). This
also removes the now unneeded resolvers late init code.

This variable for now is still set at boot time but this will ease the
transition later, as the resolvers code is now ready for this.
This commit is contained in:
Willy Tarreau 2025-04-25 09:26:44 +02:00
parent 7a79f54c98
commit 40aceb7414
1 changed files with 26 additions and 23 deletions
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49
src/resolvers.c
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@ -216,6 +216,23 @@ struct show_resolvers_ctx {
struct dns_nameserver *ns;
};
/* returns the currently accepted address families as a combination of
* RSLV_ACCEPT_IPV4 and RSLV_ACCEPT_IPV6 only. It will dynamically adapt adapt
* the IPv6 status to sock_inet6_seems_reachable if RSLV_AUTO_FAMILY is set,
* otherwise returns the relevant bits of resolv_accept_families.
*/
static inline int resolv_active_families(void)
{
if (resolv_accept_families & RSLV_AUTO_FAMILY) {
/* Let's adjust our default resolver families based on apparent IPv6 connectivity */
if (sock_inet6_seems_reachable)
return RSLV_ACCEPT_IPV4 | RSLV_ACCEPT_IPV6;
else
return RSLV_ACCEPT_IPV4;
}
return resolv_accept_families & RSLV_ACCEPT_MASK;
}
/* Returns a pointer to the resolvers matching the id <id>. NULL is returned if
* no match is found.
*/
@ -1635,11 +1652,11 @@ int resolv_get_ip_from_response(struct resolv_response *r_res,
unsigned char ip_type;
record = eb32_entry(eb32, typeof(*record), link);
if (record->type == DNS_RTYPE_A && (resolv_accept_families & RSLV_ACCEPT_IPV4)) {
if (record->type == DNS_RTYPE_A && (resolv_active_families() & RSLV_ACCEPT_IPV4)) {
ip_type = AF_INET;
ip = &record->data.in4.sin_addr;
}
else if (record->type == DNS_RTYPE_AAAA && (resolv_accept_families & RSLV_ACCEPT_IPV6)) {
else if (record->type == DNS_RTYPE_AAAA && (resolv_active_families() & RSLV_ACCEPT_IPV6)) {
ip_type = AF_INET6;
ip = &record->data.in6.sin6_addr;
}
@ -2071,8 +2088,8 @@ int resolv_link_resolution(void *requester, int requester_type, int requester_lo
hostname_dn_len = srv->hostname_dn_len;
resolvers = srv->resolvers;
query_type = !(resolv_accept_families & RSLV_ACCEPT_IPV6) ? DNS_RTYPE_A :
!(resolv_accept_families & RSLV_ACCEPT_IPV4) ? DNS_RTYPE_AAAA :
query_type = !(resolv_active_families() & RSLV_ACCEPT_IPV6) ? DNS_RTYPE_A :
!(resolv_active_families() & RSLV_ACCEPT_IPV4) ? DNS_RTYPE_AAAA :
(srv->resolv_opts.family_prio == AF_INET)
? DNS_RTYPE_A
: DNS_RTYPE_AAAA;
@ -2108,8 +2125,8 @@ int resolv_link_resolution(void *requester, int requester_type, int requester_lo
hostname_dn_len = stream->resolv_ctx.hostname_dn_len;
resolvers = stream->resolv_ctx.parent->arg.resolv.resolvers;
query_type = !(resolv_accept_families & RSLV_ACCEPT_IPV6) ? DNS_RTYPE_A :
!(resolv_accept_families & RSLV_ACCEPT_IPV4) ? DNS_RTYPE_AAAA :
query_type = !(resolv_active_families() & RSLV_ACCEPT_IPV6) ? DNS_RTYPE_A :
!(resolv_active_families() & RSLV_ACCEPT_IPV4) ? DNS_RTYPE_AAAA :
(stream->resolv_ctx.parent->arg.resolv.opts->family_prio == AF_INET)
? DNS_RTYPE_A
: DNS_RTYPE_AAAA;
@ -2342,7 +2359,7 @@ static int resolv_process_responses(struct dns_nameserver *ns)
if (!res->try)
goto report_res_error;
}
else if ((resolv_accept_families & RSLV_ACCEPT_MASK) == (RSLV_ACCEPT_IPV4 | RSLV_ACCEPT_IPV6)) {
else if (resolv_active_families() == (RSLV_ACCEPT_IPV4 | RSLV_ACCEPT_IPV6)) {
/* Fallback from A to AAAA or the opposite and re-send
* the resolution immediately. try counter is not
* decremented. */
@ -2472,10 +2489,10 @@ struct task *process_resolvers(struct task *t, void *context, unsigned int state
* the resolution immediately. try counter is not
* decremented. */
if (res->prefered_query_type == DNS_RTYPE_A &&
(resolv_accept_families & RSLV_ACCEPT_IPV6))
(resolv_active_families() & RSLV_ACCEPT_IPV6))
res->query_type = DNS_RTYPE_AAAA;
else if (res->prefered_query_type == DNS_RTYPE_AAAA &&
(resolv_accept_families & RSLV_ACCEPT_IPV4))
(resolv_active_families() & RSLV_ACCEPT_IPV4))
res->query_type = DNS_RTYPE_A;
else
res->try--;
@ -3936,19 +3953,6 @@ int cfg_post_parse_resolvers()
return err_code;
}
/* called once the config was fully parsed */
static int resolvers_late_init(void)
{
if (resolv_accept_families & RSLV_AUTO_FAMILY) {
/* Let's adjust our default resolver families based on apparent IPv6 connectivity */
if (sock_inet6_seems_reachable)
resolv_accept_families = RSLV_ACCEPT_IPV4 | RSLV_ACCEPT_IPV6;
else
resolv_accept_families = RSLV_ACCEPT_IPV4;
}
return 0;
}
/* config parser for global "dns-accept-family", accepts "ipv4", "ipv6" or both delimited by a comma */
static int cfg_parse_dns_accept_family(char **args, int section_type, struct proxy *curpx,
const struct proxy *defpx, const char *file, int line,
@ -4001,7 +4005,6 @@ REGISTER_CONFIG_SECTION("resolvers", cfg_parse_resolvers, cfg_post_parse_re
REGISTER_POST_DEINIT(resolvers_deinit);
REGISTER_CONFIG_POSTPARSER("dns runtime resolver", resolvers_finalize_config);
REGISTER_PRE_CHECK(resolvers_create_default);
REGISTER_POST_CHECK(resolvers_late_init);
#if defined(USE_PROMEX)