From 7264dfe9495a7bfd784b8964508e4204b7e077af Mon Sep 17 00:00:00 2001 From: Baptiste Assmann Date: Wed, 30 Oct 2019 16:06:53 +0100 Subject: [PATCH] BUG/MINOR: action: do-resolve now use cached response As reported by David Birdsong on the ML, the HTTP action do-resolve does not use the DNS cache. Actually, the action is "registred" to the resolution for said name to be resolved and wait until an other requester triggers the it. Once the resolution is finished, then the action is updated with the result. To trigger this, you must have a server with runtime DNS resolution enabled and run a do-resolve action with the same fqdn AND they use the same resolvers section. This patch fixes this behavior by ensuring the resolution associated to the action has a valid answer which is not considered as expired. If those conditions are valid, then we can use it (it's the "cache"). Backport status: 2.0 --- src/dns.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/src/dns.c b/src/dns.c index 15d40a13a..000128960 100644 --- a/src/dns.c +++ b/src/dns.c @@ -2150,8 +2150,13 @@ enum act_return dns_action_do_resolve(struct act_rule *rule, struct proxy *px, struct dns_resolution *resolution; struct sample *smp; char *fqdn; + struct dns_requester *req; + struct dns_resolvers *resolvers; + struct dns_resolution *res; + int exp; /* we have a response to our DNS resolution */ + use_cache: if (s->dns_ctx.dns_requester && s->dns_ctx.dns_requester->resolution != NULL) { resolution = s->dns_ctx.dns_requester->resolution; if (resolution->step == RSLV_STEP_RUNNING) { @@ -2211,6 +2216,22 @@ enum act_return dns_action_do_resolve(struct act_rule *rule, struct proxy *px, s->dns_ctx.parent = rule; dns_link_resolution(s, OBJ_TYPE_STREAM, 0); + + /* Check if there is a fresh enough response in the cache of our associated resolution */ + req = s->dns_ctx.dns_requester; + if (!req || !req->resolution) { + dns_trigger_resolution(s->dns_ctx.dns_requester); + return ACT_RET_YIELD; + } + res = req->resolution; + resolvers = res->resolvers; + + exp = tick_add(res->last_resolution, resolvers->hold.valid); + if (resolvers->t && res->status == RSLV_STATUS_VALID && tick_isset(res->last_resolution) + && !tick_is_expired(exp, now_ms)) { + goto use_cache; + } + dns_trigger_resolution(s->dns_ctx.dns_requester); return ACT_RET_YIELD; }