From 2c5573e894dd7c64d2afd03c4934c30ff333fc8f Mon Sep 17 00:00:00 2001
From: David CARLIER <devnexen@gmail.com>
Date: Tue, 28 Dec 2021 07:20:10 +0000
Subject: [PATCH] Check somaxconn system settings on macOS, FreeBSD and
 OpenBSD. (#9972)

Co-authored-by: Yossi Gottlieb <yossigo@gmail.com>
---
 src/config.h |  7 +++++++
 src/server.c | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/config.h b/src/config.h
index da29e4cd1..210e55a87 100644
--- a/src/config.h
+++ b/src/config.h
@@ -63,6 +63,13 @@
 #define HAVE_TASKINFO 1
 #endif
 
+/* Test for somaxconn check */
+#if defined(__APPLE__) || defined(__FreeBSD__)
+#define HAVE_SYSCTL_KIPC_SOMAXCONN 1
+#elif defined(__OpenBSD__)
+#define HAVE_SYSCTL_KERN_SOMAXCONN 1
+#endif
+
 /* Test for backtrace() */
 #if defined(__APPLE__) || (defined(__linux__) && defined(__GLIBC__)) || \
     defined(__FreeBSD__) || ((defined(__OpenBSD__) || defined(__NetBSD__)) && defined(USE_BACKTRACE))\
diff --git a/src/server.c b/src/server.c
index fa40771ab..046f9ac74 100644
--- a/src/server.c
+++ b/src/server.c
@@ -64,6 +64,10 @@
 #include <sys/mman.h>
 #endif
 
+#if defined(HAVE_SYSCTL_KIPC_SOMAXCONN) || defined(HAVE_SYSCTL_KERN_SOMAXCONN)
+#include <sys/sysctl.h>
+#endif
+
 /* Our shared "common" objects */
 
 struct sharedObjectsStruct shared;
@@ -2028,7 +2032,7 @@ void adjustOpenFilesLimit(void) {
 /* Check that server.tcp_backlog can be actually enforced in Linux according
  * to the value of /proc/sys/net/core/somaxconn, or warn about it. */
 void checkTcpBacklogSettings(void) {
-#ifdef HAVE_PROC_SOMAXCONN
+#if defined(HAVE_PROC_SOMAXCONN)
     FILE *fp = fopen("/proc/sys/net/core/somaxconn","r");
     char buf[1024];
     if (!fp) return;
@@ -2039,6 +2043,31 @@ void checkTcpBacklogSettings(void) {
         }
     }
     fclose(fp);
+#elif defined(HAVE_SYSCTL_KIPC_SOMAXCONN)
+    int somaxconn, mib[3];
+    size_t len = sizeof(int);
+
+    mib[0] = CTL_KERN;
+    mib[1] = KERN_IPC;
+    mib[2] = KIPC_SOMAXCONN;
+
+    if (sysctl(mib, 3, &somaxconn, &len, NULL, 0) == 0) {
+        if (somaxconn > 0 && somaxconn < server.tcp_backlog) {
+            serverLog(LL_WARNING,"WARNING: The TCP backlog setting of %d cannot be enforced because kern.ipc.somaxconn is set to the lower value of %d.", server.tcp_backlog, somaxconn);
+        }
+    }
+#elif defined(HAVE_SYSCTL_KERN_SOMAXCONN)
+    int somaxconn, mib[2];
+    size_t len = sizeof(int);
+
+    mib[0] = CTL_KERN;
+    mib[1] = KERN_SOMAXCONN;
+
+    if (sysctl(mib, 2, &somaxconn, &len, NULL, 0) == 0) {
+        if (somaxconn > 0 && somaxconn < server.tcp_backlog) {
+            serverLog(LL_WARNING,"WARNING: The TCP backlog setting of %d cannot be enforced because kern.somaxconn is set to the lower value of %d.", server.tcp_backlog, somaxconn);
+        }
+    }
 #endif
 }