Function to allow plugins to publish messages.

ChangeLog.txt

@@ -12,6 +12,8 @@ Broker:
   to a v3.x only broker.
 - DLT logging is now configurable at runtime with `log_dest dlt`.
   Closes #1735.
+- Add `mosquitto_plugin_publish()` function, which can be used by plugins to
+  publish messages.
 
 Client library:
 - Client no longer generates random client ids for v3.1.1 clients, these are

src/linker.syms

@@ -1,12 +1,13 @@
 {
-	mosquitto_log_printf;
 	mosquitto_client_address;
+	mosquitto_client_certificate;
 	mosquitto_client_clean_session;
 	mosquitto_client_id;
 	mosquitto_client_keepalive;
-	mosquitto_client_certificate;
 	mosquitto_client_protocol;
 	mosquitto_client_sub_count;
 	mosquitto_client_username;
+	mosquitto_log_printf;
+	mosquitto_plugin_publish;
 	mosquitto_set_username;
 };

src/loop.c

@@ -38,6 +38,7 @@ Contributors:
 #  include <sys/socket.h>
 #endif
 #include <time.h>
+#include <utlist.h>
 
 #ifdef WITH_WEBSOCKETS
 #  include <libwebsockets.h>
@@ -98,6 +99,19 @@ void lws__sul_callback(struct lws_sorted_usec_list *l)
 static struct lws_sorted_usec_list sul;
 #endif
 
+
+void queue_plugin_msgs(struct mosquitto_db *db)
+{
+	struct mosquitto_message_v5 *msg, *tmp;
+
+	DL_FOREACH_SAFE(db->plugin_msgs, msg, tmp){
+		DL_DELETE(db->plugin_msgs, msg);
+		db__messages_easy_queue(db, NULL, msg->topic, msg->qos, msg->payloadlen, msg->payload, msg->retain, 0, &msg->properties);
+		mosquitto__free(msg);
+	}
+}
+
+
 int mosquitto_main_loop(struct mosquitto_db *db, mosq_sock_t *listensock, int listensock_count)
 {
 #ifdef WITH_SYS_TREE
@@ -130,6 +144,7 @@ int mosquitto_main_loop(struct mosquitto_db *db, mosq_sock_t *listensock, int li
 #endif
 
 	while(run){
+		queue_plugin_msgs(db);
 		context__free_disused(db);
 #ifdef WITH_SYS_TREE
 		if(db->config->sys_interval > 0){

src/mosquitto_broker.h

@@ -24,6 +24,7 @@ extern "C" {
 #include <stdbool.h>
 
 struct mosquitto;
+typedef struct mqtt5__property mosquitto_property;
 
 enum mosquitto_protocol {
 	mp_mqtt,
@@ -165,6 +166,25 @@ const char *mosquitto_client_username(const struct mosquitto *client);
  */
 int mosquitto_set_username(struct mosquitto *client, const char *username);
 
+
+/* Function: mosquitto_plugin_publish
+ *
+ * Publish a message from within a plugin.
+ *
+ * This function allows a plugin to publish a message. Messages published in
+ * this way are treated as coming from the broker and so will not be passed to
+ * `mosquitto_auth_acl_check(, MOSQ_ACL_WRITE, , )` for checking. Read access
+ * will be enforced as normal for individual clients when they are due to
+ * receive the message.
+ */
+int mosquitto_plugin_publish(
+		const char *topic,
+		int payloadlen,
+		const void *payload,
+		int qos,
+		bool retain,
+		mosquitto_property *properties);
+
 #ifdef __cplusplus
 }
 #endif

src/mosquitto_broker_internal.h

@@ -440,6 +440,18 @@ struct mosquitto__acl_user{
 	struct mosquitto__acl *acl;
 };
 
+
+struct mosquitto_message_v5{
+	struct mosquitto_message_v5 *next, *prev;
+	char *topic;
+	void *payload;
+	mosquitto_property *properties;
+	int payloadlen;
+	int qos;
+	bool retain;
+};
+
+
 struct mosquitto_db{
 	dbid_t last_db_id;
 	struct mosquitto__subhier *subs;
@@ -474,6 +486,7 @@ struct mosquitto_db{
 #ifdef WITH_EPOLL
 	int epollfd;
 #endif
+	struct mosquitto_message_v5 *plugin_msgs;
 };
 
 enum mosquitto__bridge_direction{

src/plugin.c

@@ -20,6 +20,7 @@ Contributors:
 #include "mosquitto_internal.h"
 #include "mosquitto_broker.h"
 #include "memory_mosq.h"
+#include "utlist.h"
 
 #ifdef WITH_TLS
 #  include <openssl/ssl.h>
@@ -94,6 +95,39 @@ const char *mosquitto_client_username(const struct mosquitto *context)
 	}
 }
 
+
+int mosquitto_plugin_publish(
+		const char *topic,
+		int payloadlen,
+		const void *payload,
+		int qos,
+		bool retain,
+		mosquitto_property *properties)
+{
+	struct mosquitto_message_v5 *msg;
+	struct mosquitto_db *db;
+
+	msg = mosquitto__malloc(sizeof(struct mosquitto_message_v5));
+	if(msg == NULL) return MOSQ_ERR_NOMEM;
+	
+	msg->next = NULL;
+	msg->prev = NULL;
+	msg->topic = mosquitto__strdup(topic);
+	msg->payloadlen = payloadlen;
+	msg->payload = mosquitto__calloc(1, payloadlen+1);
+	memcpy(msg->payload, payload, payloadlen);
+	msg->qos = qos;
+	msg->retain = retain;
+	msg->properties = properties;
+
+	db = mosquitto__get_db();
+
+	DL_APPEND(db->plugin_msgs, msg);
+
+	return MOSQ_ERR_SUCCESS;
+}
+
+
 int mosquitto_set_username(struct mosquitto *client, const char *username)
 {
 	char *u_dup;