From b660283e64b9e26f5f23a0c0d996265a453c1a7c Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Wed, 9 Oct 2019 10:52:58 +0100
Subject: [PATCH] Basic MQTT v5 support for bridges.

This gives equivalent behaviour as for v3.1.1/v3.1 bridges, there is no extra functionality yet.
---
 lib/send_connect.c       |  2 +-
 man/mosquitto.conf.5.xml |  7 ++++---
 mosquitto.conf           |  2 +-
 src/bridge.c             | 10 +++++++++-
 src/conf.c               |  2 ++
 5 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/lib/send_connect.c b/lib/send_connect.c
index 0f13dee2..f3293cb8 100644
--- a/lib/send_connect.c
+++ b/lib/send_connect.c
@@ -141,7 +141,7 @@ int send__connect(struct mosquitto *mosq, uint16_t keepalive, bool clean_session
 		packet__write_string(packet, PROTOCOL_NAME, strlen(PROTOCOL_NAME));
 	}
 #if defined(WITH_BROKER) && defined(WITH_BRIDGE)
-	if(mosq->bridge && mosq->bridge->try_private && mosq->bridge->try_private_accepted){
+	if(mosq->bridge && mosq->bridge->protocol_version != mosq_p_mqtt5 && mosq->bridge->try_private && mosq->bridge->try_private_accepted){
 		version |= 0x80;
 	}else{
 	}
diff --git a/man/mosquitto.conf.5.xml b/man/mosquitto.conf.5.xml
index 387ff36c..7d48703d 100644
--- a/man/mosquitto.conf.5.xml
+++ b/man/mosquitto.conf.5.xml
@@ -1505,9 +1505,10 @@ openssl dhparam -out dhparam.pem 2048</programlisting>
 				<listitem>
 					<para>Set the version of the MQTT protocol to use with for
 						this bridge. Can be one of
-						<replaceable>mqttv31</replaceable> or
-						<replaceable>mqttv311</replaceable>. Defaults to
-						<replaceable>mqttv31</replaceable>.</para>
+						<replaceable>mqttv50</replaceable>,
+						<replaceable>mqttv311</replaceable> or
+						<replaceable>mqttv31</replaceable>. Defaults to
+						<replaceable>mqttv311</replaceable>.</para>
 				</listitem>
 			</varlistentry>
 			<varlistentry>
diff --git a/mosquitto.conf b/mosquitto.conf
index 2117d9e8..a9b13d62 100644
--- a/mosquitto.conf
+++ b/mosquitto.conf
@@ -824,7 +824,7 @@
 #bridge_attempt_unsubscribe true
 
 # Set the version of the MQTT protocol to use with for this bridge. Can be one
-# of mqttv311 or mqttv11. Defaults to mqttv311.
+# of mqttv50, mqttv311 or mqttv31. Defaults to mqttv311.
 #bridge_protocol_version mqttv311
 
 # Set the clean session variable for this bridge.
diff --git a/src/bridge.c b/src/bridge.c
index 18cde94c..ed66a7ef 100644
--- a/src/bridge.c
+++ b/src/bridge.c
@@ -445,6 +445,7 @@ int bridge__on_connect(struct mosquitto_db *db, struct mosquitto *context)
 	char *notification_topic;
 	int notification_topic_len;
 	char notification_payload;
+	int sub_opts;
 
 	if(context->bridge->notifications){
 		notification_payload = '1';
@@ -478,7 +479,14 @@ int bridge__on_connect(struct mosquitto_db *db, struct mosquitto *context)
 	}
 	for(i=0; i<context->bridge->topic_count; i++){
 		if(context->bridge->topics[i].direction == bd_in || context->bridge->topics[i].direction == bd_both){
-			if(send__subscribe(context, NULL, 1, &context->bridge->topics[i].remote_topic, context->bridge->topics[i].qos, NULL)){
+			sub_opts = context->bridge->topics[i].qos;
+			if(context->bridge->protocol_version == mosq_p_mqtt5){
+				sub_opts = sub_opts
+					| MQTT_SUB_OPT_NO_LOCAL
+					| MQTT_SUB_OPT_RETAIN_AS_PUBLISHED
+					| MQTT_SUB_OPT_SEND_RETAIN_ALWAYS;
+			}
+			if(send__subscribe(context, NULL, 1, &context->bridge->topics[i].remote_topic, sub_opts, NULL)){
 				return 1;
 			}
 		}else{
diff --git a/src/conf.c b/src/conf.c
index 171a6966..e4342571 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -1121,6 +1121,8 @@ int config__read_file_core(struct mosquitto__config *config, bool reload, struct
 							cur_bridge->protocol_version = mosq_p_mqtt31;
 						}else if(!strcmp(token, "mqttv311")){
 							cur_bridge->protocol_version = mosq_p_mqtt311;
+						}else if(!strcmp(token, "mqttv50")){
+							cur_bridge->protocol_version = mosq_p_mqtt5;
 						}else{
 							log__printf(NULL, MOSQ_LOG_ERR, "Error: Invalid bridge_protocol_version value (%s).", token);
 							return MOSQ_ERR_INVAL;