From 75c484e36d6d28da820bfcf530a28b4f785049a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Sur=C3=BD?= <ondrej@isc.org>
Date: Wed, 1 Dec 2021 17:41:20 +0100
Subject: [PATCH] Improve the logging on failed TCP accept

Previously, when TCP accept failed, we have logged a message with
ISC_LOG_ERROR level.  One common case, how this could happen is that the
client hits TCP client quota and is put on hold and when resumed, the
client has already given up and closed the TCP connection.  In such
case, the named would log:

    TCP connection failed: socket is not connected

This message was quite confusing because it actually doesn't say that
it's related to the accepting the TCP connection and also it logs
everything on the ISC_LOG_ERROR level.

Change the log message to "Accepting TCP connection failed" and for
specific error states lower the severity of the log message to
ISC_LOG_INFO.

(cherry picked from commit 20ac73eb222e60395399b467b0a72015a4dd8845)
Conflict: NA
Reference: https://gitlab.isc.org/isc-projects/bind9/-/commit/75c484e36d6d28da820bfcf530a28b4f785049a6
---
 lib/isc/netmgr/netmgr-int.h |  3 +++
 lib/isc/netmgr/netmgr.c     | 27 +++++++++++++++++++++++++++
 lib/isc/netmgr/tcp.c        | 20 ++------------------
 lib/isc/netmgr/tcpdns.c     | 22 ++--------------------
 4 files changed, 34 insertions(+), 38 deletions(-)

diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index f7b54f9..b4299d5 100644
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -1576,4 +1576,7 @@ isc__nm_failed_read_cb(isc_nmsocket_t *sock, isc_result_t result, bool async);
 void
 isc__nmsocket_connecttimeout_cb(uv_timer_t *timer);

+void
+isc__nm_accept_connection_log(isc_result_t result, bool can_log_quota);
+
 #define STREAM_CLIENTS_PER_CONN 23
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index 3283eb6e4f..54042a9123 100644
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -1967,6 +1967,33 @@ isc__nmsocket_connecttimeout_cb(uv_timer_t *timer) {
 	}
 }
 
+void
+isc__nm_accept_connection_log(isc_result_t result, bool can_log_quota) {
+	int level;
+
+	switch (result) {
+	case ISC_R_SUCCESS:
+	case ISC_R_NOCONN:
+		return;
+	case ISC_R_QUOTA:
+	case ISC_R_SOFTQUOTA:
+		if (!can_log_quota) {
+			return;
+		}
+		level = ISC_LOG_INFO;
+		break;
+	case ISC_R_NOTCONNECTED:
+		level = ISC_LOG_INFO;
+		break;
+	default:
+		level = ISC_LOG_ERROR;
+	}
+
+	isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL, ISC_LOGMODULE_NETMGR,
+		      level, "Accepting TCP connection failed: %s",
+		      isc_result_totext(result));
+}
+
 static void
 isc__nmsocket_readtimeout_cb(uv_timer_t *timer) {
 	isc_nmsocket_t *sock = uv_handle_get_data((uv_handle_t *)timer);
diff --git a/lib/isc/netmgr/tcp.c b/lib/isc/netmgr/tcp.c
index 5cca9f5214..1b5e80d3a7 100644
--- a/lib/isc/netmgr/tcp.c
+++ b/lib/isc/netmgr/tcp.c
@@ -631,15 +631,7 @@ tcp_connection_cb(uv_stream_t *server, int status) {
 
 	result = accept_connection(ssock, quota);
 done:
-	if (result != ISC_R_SUCCESS && result != ISC_R_NOCONN) {
-		if ((result != ISC_R_QUOTA && result != ISC_R_SOFTQUOTA) ||
-		    can_log_tcp_quota()) {
-			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
-				      ISC_LOGMODULE_NETMGR, ISC_LOG_ERROR,
-				      "TCP connection failed: %s",
-				      isc_result_totext(result));
-		}
-	}
+	isc__nm_accept_connection_log(result, can_log_tcp_quota());
 }
 
 void
@@ -934,15 +926,7 @@ isc__nm_async_tcpaccept(isc__networker_t *worker, isc__netievent_t *ev0) {
 	REQUIRE(sock->tid == isc_nm_tid());
 
 	result = accept_connection(sock, ievent->quota);
-	if (result != ISC_R_SUCCESS && result != ISC_R_NOCONN) {
-		if ((result != ISC_R_QUOTA && result != ISC_R_SOFTQUOTA) ||
-		    can_log_tcp_quota()) {
-			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
-				      ISC_LOGMODULE_NETMGR, ISC_LOG_ERROR,
-				      "TCP connection failed: %s",
-				      isc_result_totext(result));
-		}
-	}
+	isc__nm_accept_connection_log(result, can_log_tcp_quota());
 }
 
 static isc_result_t
diff --git a/lib/isc/netmgr/tcpdns.c b/lib/isc/netmgr/tcpdns.c
index 188790c8b4..b76dcbc66c 100644
--- a/lib/isc/netmgr/tcpdns.c
+++ b/lib/isc/netmgr/tcpdns.c
@@ -600,16 +600,7 @@ tcpdns_connection_cb(uv_stream_t *server, int status) {
 
 	result = accept_connection(ssock, quota);
 done:
-	if (result != ISC_R_SUCCESS && result != ISC_R_NOCONN) {
-		if ((result != ISC_R_QUOTA && result != ISC_R_SOFTQUOTA) ||
-		    can_log_tcpdns_quota())
-		{
-			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
-				      ISC_LOGMODULE_NETMGR, ISC_LOG_ERROR,
-				      "TCP connection failed: %s",
-				      isc_result_totext(result));
-		}
-	}
+	isc__nm_accept_connection_log(result, can_log_tcpdns_quota());
 }
 
 void
@@ -905,16 +896,7 @@ isc__nm_async_tcpdnsaccept(isc__networker_t *worker, isc__netievent_t *ev0) {
 	REQUIRE(ievent->sock->tid == isc_nm_tid());
 
 	result = accept_connection(ievent->sock, ievent->quota);
-	if (result != ISC_R_SUCCESS && result != ISC_R_NOCONN) {
-		if ((result != ISC_R_QUOTA && result != ISC_R_SOFTQUOTA) ||
-		    can_log_tcpdns_quota())
-		{
-			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
-				      ISC_LOGMODULE_NETMGR, ISC_LOG_ERROR,
-				      "TCP connection failed: %s",
-				      isc_result_totext(result));
-		}
-	}
+	isc__nm_accept_connection_log(result, can_log_tcpdns_quota());
 }
 
 static isc_result_t
-- 
2.27.0