[Fix] upstream: preserve backoff for pending-resolve

set_active stopped the timer and re-armed at INITIAL_DELAY (~1s),
discarding the exponential backoff lazy_resolve_cb had accumulated.
Snapshot ev.repeat before stopping and reuse it when the upstream is
still PENDING_RESOLVE so repeated DNS failures actually back off.

diff --git a/src/libutil/upstream.c b/src/libutil/upstream.c
index 9aa0dd7f6a78c5e8089593ca6740b44af192b3bb..0e4943ffe5ab83c0d96eb5fb39e2c498215b8f18 100644 (file)
--- a/src/libutil/upstream.c
+++ b/src/libutil/upstream.c
@@ -460,6 +460,13 @@ rspamd_upstream_set_active(struct upstream_list *ls, struct upstream *upstream)
                !((upstream->flags & RSPAMD_UPSTREAM_FLAG_NORESOLVE) ||
                  (upstream->flags & RSPAMD_UPSTREAM_FLAG_DNS))) {
 
+               /*
+                * Snapshot any backoff state already accumulated by lazy_resolve_cb
+                * before we stop the timer, so we can preserve it for pending
+                * upstreams that aren't yet resolved.
+                */
+               double prev_repeat = ev_can_stop(&upstream->ev) ? upstream->ev.repeat : 0.0;
+
                if (ev_can_stop(&upstream->ev)) {
                        ev_timer_stop(upstream->ctx->event_loop, &upstream->ev);
                }
@@ -472,9 +479,18 @@ rspamd_upstream_set_active(struct upstream_list *ls, struct upstream *upstream)
                        when = 0.0;
                }
                else if (is_pending) {
-                       /* Retry quickly while we have no addresses */
-                       when = rspamd_time_jitter(UPSTREAM_PENDING_RESOLVE_INITIAL_DELAY,
-                                                                         UPSTREAM_PENDING_RESOLVE_INITIAL_DELAY * .25);
+                       /*
+                        * Keep the backoff already grown by repeated lazy_resolve_cb
+                        * runs; falling back to the initial delay would mask repeated
+                        * DNS failure with optimistic 1s retries.
+                        */
+                       if (prev_repeat >= UPSTREAM_PENDING_RESOLVE_INITIAL_DELAY) {
+                               when = prev_repeat;
+                       }
+                       else {
+                               when = rspamd_time_jitter(UPSTREAM_PENDING_RESOLVE_INITIAL_DELAY,
+                                                                                 UPSTREAM_PENDING_RESOLVE_INITIAL_DELAY * .25);
+                       }
                }
                else {
                        when = rspamd_time_jitter(upstream->ls->limits->lazy_resolve_time,