From dc6c04b24382acca435878d6edb12dcc17cf3ca2 Mon Sep 17 00:00:00 2001
From: "W.C.A. Wijngaards" <wouter@nlnetlabs.nl>
Date: Fri, 12 Aug 2022 09:54:29 +0200
Subject: [PATCH] - Fix to log accept error ENFILE and EMFILE errno, but
 slowly, once   per 10 seconds. Also log accept failures when no slow down is
 used.

---
 doc/Changelog   |  4 ++++
 util/netevent.c | 14 ++++++++++++++
 util/netevent.h |  2 ++
 3 files changed, 20 insertions(+)

diff --git a/doc/Changelog b/doc/Changelog
index 24605888b..0e67bf0b1 100644
--- a/doc/Changelog
+++ b/doc/Changelog
@@ -1,3 +1,7 @@
+12 August 2022: Wouter
+	- Fix to log accept error ENFILE and EMFILE errno, but slowly, once
+	  per 10 seconds. Also log accept failures when no slow down is used.
+
 5 August 2022: Wouter
 	- Fix #734 [FR] enable unbound-checkconf to detect more (basic)
 	  errors.
diff --git a/util/netevent.c b/util/netevent.c
index 841e09787..c2b1ac7d4 100644
--- a/util/netevent.c
+++ b/util/netevent.c
@@ -132,6 +132,8 @@ struct internal_base {
 	struct ub_event* slow_accept;
 	/** true if slow_accept is enabled */
 	int slow_accept_enabled;
+	/** last log time for slow logging of file descriptor errors */
+	time_t last_slow_log;
 };
 
 /**
@@ -889,6 +891,15 @@ int comm_point_perform_accept(struct comm_point* c,
 				struct timeval tv;
 				verbose(VERB_ALGO, "out of file descriptors: "
 					"slow accept");
+				ub_comm_base_now(b);
+				if(b->eb->last_slow_log+SLOW_LOG_TIME <=
+					b->eb->secs) {
+					b->eb->last_slow_log = b->eb->secs;
+					log_err("accept failed, slow down "
+						"accept for %d msec: %s",
+						NETEVENT_SLOW_ACCEPT_TIME,
+						sock_strerror(errno));
+				}
 				b->eb->slow_accept_enabled = 1;
 				fptr_ok(fptr_whitelist_stop_accept(
 					b->stop_accept));
@@ -909,6 +920,9 @@ int comm_point_perform_accept(struct comm_point* c,
 					/* we do not want to log here,
 					 * error: "event_add failed." */
 				}
+			} else {
+				log_err("accept, with no slow down, "
+					"failed: %s", sock_strerror(errno));
 			}
 			return -1;
 		}
diff --git a/util/netevent.h b/util/netevent.h
index 9f4d28ba9..4e82703e0 100644
--- a/util/netevent.h
+++ b/util/netevent.h
@@ -102,6 +102,8 @@ typedef int comm_point_callback_type(struct comm_point*, void*, int,
 
 /** timeout to slow accept calls when not possible, in msec. */
 #define NETEVENT_SLOW_ACCEPT_TIME 2000
+/** timeout to slow down log print, so it does not spam the logs, in sec */
+#define SLOW_LOG_TIME 10
 
 /**
  * A communication point dispatcher. Thread specific.
-- 
2.47.3