From 072103823b42b07b55b94cb0ffc4febac3c348ad Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Mon, 8 Mar 2021 13:19:34 +0000
Subject: [PATCH] Increase maximum connection count on Windows from 2048 to
 8192.

This is only where supported.

Closes #2122. Thanks to yellowgg2.
---
 ChangeLog.txt   | 2 ++
 src/mosquitto.c | 8 +++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/ChangeLog.txt b/ChangeLog.txt
index 69031fae..594d6d58 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -7,6 +7,8 @@ Broker:
 - Add connection-state example plugin to demonstrate MOSQ_EVT_CONNECT.
 - Plugins on non-Windows platforms now no longer make their symbols globally
   available, which means they are self contained.
+- Increase maximum connection count on Windows from 2048 to 8192 where
+  supported. Closes #2122.
 
 Client library:
 - Add MOSQ_OPT_DISABLE_SOCKETPAIR to allow the disabling of the socketpair
diff --git a/src/mosquitto.c b/src/mosquitto.c
index 53cd85f2..0fe8ba02 100644
--- a/src/mosquitto.c
+++ b/src/mosquitto.c
@@ -481,7 +481,13 @@ int main(int argc, char *argv[])
 #endif
 
 #ifdef WIN32
-	_setmaxstdio(2048);
+	if(_setmaxstdio(8192) != 8192){
+		/* Old limit was 2048 */
+		if(_setmaxstdio(2048) != 2048){
+			log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Unable to increase maximum allowed connections. This session may be limited to 512 connections.");
+		}
+	}
+
 #endif
 
 	memset(&db, 0, sizeof(struct mosquitto_db));