Increase maximum connection count on Windows from 2048 to 8192.

This is only where supported.

Closes #2122. Thanks to yellowgg2.

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

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));