Fix reloading of listeners where multiple listeners have the same port.

This is only possible where they have different bind addresses.

Closes #2029. Thanks to Simon Aldrich.

ChangeLog.txt

@@ -7,6 +7,8 @@ Broker:
 - Add notes that libsystemd-dev or similar is needed if building with systemd
   support. Closes #2019.
 - Improve logging in obscure cases when a client disconnects. Closes #2017.
+- Fix reloading of listeners where multiple listeners have been defined with
+  the same port but different bind addresses. Closes #2029.
 
 Apps:
 - Allow command line arguments to override config file options in

src/conf.c

@@ -1417,9 +1417,22 @@ int config__read_file_core(struct mosquitto__config *config, bool reload, struct
 							{
 								for(i=0; i<config->listener_count; i++){
 									if(config->listeners[i].port == tmp_int){
+										/* Now check we have a matching bind address, if defined */
+										if(config->listeners[i].host){
+											if(token && !strcmp(config->listeners[i].host, token)){
+												/* They both have a bind address, and they match */
 												cur_listener = &config->listeners[i];
 												break;
 											}
+										}else{
+											if(token == NULL){
+												/* Neither this config nor the new config have a bind address,
+												 * so they match. */
+												cur_listener = &config->listeners[i];
+												break;
+											}
+										}
+									}
 								}
 							}
 							if(!cur_listener){