plugin example: add user properties

Signed-off-by: Simon Christmann <simon@christmann.email>

plugins/add-user-properties/CMakeLists.txt

@@ -0,0 +1,11 @@
+include_directories(${mosquitto_SOURCE_DIR} ${mosquitto_SOURCE_DIR}/include
+			${STDBOOL_H_PATH} ${STDINT_H_PATH})
+
+add_library(mosquitto_message_timestamp SHARED mosquitto_message_timestamp.c)
+set_target_properties(mosquitto_message_timestamp PROPERTIES
+	POSITION_INDEPENDENT_CODE 1
+)
+set_target_properties(mosquitto_message_timestamp PROPERTIES PREFIX "")
+
+# Don't install, these are example plugins only.
+#install(TARGETS mosquitto_message_timestamp RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}")

plugins/add-user-properties/Makefile

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+include ../../config.mk
+
+.PHONY : all binary check clean reallyclean test install uninstall
+
+PLUGIN_NAME=add_properties
+
+all : binary
+
+binary : ${PLUGIN_NAME}.so
+
+${PLUGIN_NAME}.so : ${PLUGIN_NAME}.c
+	$(CROSS_COMPILE)$(CC) $(PLUGIN_CPPFLAGS) $(PLUGIN_CFLAGS) $(PLUGIN_LDFLAGS) -fPIC -shared $< -o $@
+
+reallyclean : clean
+clean:
+	-rm -f *.o ${PLUGIN_NAME}.so *.gcda *.gcno
+
+check: test
+test:
+
+install: ${PLUGIN_NAME}.so
+	# Don't install, these are examples only.
+	#$(INSTALL) -d "${DESTDIR}$(libdir)"
+	#$(INSTALL) ${STRIP_OPTS} ${PLUGIN_NAME}.so "${DESTDIR}${libdir}/${PLUGIN_NAME}.so"
+
+uninstall :
+	-rm -f "${DESTDIR}${libdir}/${PLUGIN_NAME}.so"

plugins/add-user-properties/add_properties.c

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+/*
+Copyright (c) 2020 Roger Light <roger@atchoo.org>
+
+All rights reserved. This program and the accompanying materials
+are made available under the terms of the Eclipse Public License 2.0
+and Eclipse Distribution License v1.0 which accompany this distribution.
+ 
+The Eclipse Public License is available at
+   https://www.eclipse.org/legal/epl-2.0/
+and the Eclipse Distribution License is available at
+  http://www.eclipse.org/org/documents/edl-v10.php.
+ 
+SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+
+Contributors:
+   Roger Light - initial implementation and documentation.
+   Simon Christmann - use timestamp in unix epoch milliseconds; add client properties
+*/
+
+/*
+ * Adds MQTT v5 user-properties to incoming messages:
+ *  - $timestamp: unix epoch in milliseconds
+ *  - $client_id: client id of the publishing client
+ *  - $client_username: username that the publishing client used to authenticate
+ *
+ * Compile with:
+ *   gcc -I<path to mosquitto-repo/include> -fPIC -shared add_properties.c -o add_properties.so
+ *
+ * Use in config with:
+ *
+ *   plugin /path/to/add_properties.so
+ *
+ * Note that this only works on Mosquitto 2.0 or later.
+ */
+#include "config.h"
+
+#include <stdio.h>
+#include <time.h>
+
+#include "mosquitto_broker.h"
+#include "mosquitto_plugin.h"
+#include "mosquitto.h"
+#include "mqtt_protocol.h"
+
+#define TS_BUF_LEN (14+1)  // 14 characters in unix epoch (ms) is ≈16 Nov 5138
+
+static mosquitto_plugin_id_t *mosq_pid = NULL;
+
+static int callback_message(int event, void *event_data, void *userdata)
+{
+	struct mosquitto_evt_message *ed = event_data;
+
+	UNUSED(event);
+	UNUSED(userdata);
+
+	int result;
+
+	// Add timestamp in unix epoch (ms)
+	struct timespec ts;
+	char ts_buf[TS_BUF_LEN];
+	clock_gettime(CLOCK_REALTIME, &ts);
+	snprintf(ts_buf, TS_BUF_LEN, "%li%03lu", ts.tv_sec, ts.tv_nsec / 1000 / 1000);
+	
+	result = mosquitto_property_add_string_pair(
+		&ed->properties,
+		MQTT_PROP_USER_PROPERTY,
+		"$timestamp",
+		ts_buf);
+	if (result != MOSQ_ERR_SUCCESS) return result;
+
+	// Add client id
+	result = mosquitto_property_add_string_pair(
+		&ed->properties,
+		MQTT_PROP_USER_PROPERTY,
+		"$client_id",
+		mosquitto_client_id(ed->client));
+	if (result != MOSQ_ERR_SUCCESS) return result;
+
+	// Add client username
+	result = mosquitto_property_add_string_pair(
+		&ed->properties,
+		MQTT_PROP_USER_PROPERTY,
+		"$client_username",
+		mosquitto_client_username(ed->client));
+	if (result != MOSQ_ERR_SUCCESS) return result;
+
+	// If no return occurred up to this point, we were successful
+	return MOSQ_ERR_SUCCESS;
+}
+
+int mosquitto_plugin_version(int supported_version_count, const int *supported_versions)
+{
+	int i;
+
+	for(i=0; i<supported_version_count; i++){
+		if(supported_versions[i] == 5){
+			return 5;
+		}
+	}
+	return -1;
+}
+
+int mosquitto_plugin_init(mosquitto_plugin_id_t *identifier, void **user_data, struct mosquitto_opt *opts, int opt_count)
+{
+	UNUSED(user_data);
+	UNUSED(opts);
+	UNUSED(opt_count);
+
+	mosq_pid = identifier;
+	return mosquitto_callback_register(mosq_pid, MOSQ_EVT_MESSAGE, callback_message, NULL, NULL);
+}
+
+int mosquitto_plugin_cleanup(void *user_data, struct mosquitto_opt *opts, int opt_count)
+{
+	UNUSED(user_data);
+	UNUSED(opts);
+	UNUSED(opt_count);
+
+	return mosquitto_callback_unregister(mosq_pid, MOSQ_EVT_MESSAGE, callback_message, NULL);
+}