Use cJSON for producing JSON output in clients.

Closes #1222. Thanks to Ben Barbour.

CMakeLists.txt

@@ -13,6 +13,8 @@ cmake_minimum_required(VERSION 2.8)
 
 set (VERSION 1.6.7)
 
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/")
+
 add_definitions (-DCMAKE -DVERSION=\"${VERSION}\")
 
 if (WIN32)

ChangeLog.txt

@@ -15,6 +15,7 @@ Clients:
   `mosquitto_rr -W <secs>`. Closes #275.
 - Add support for connecting to brokers through Unix domain sockets with the
   `--unix` argument.
+- Use cJSON library for producing JSON output, where available. Closes #1222.
 
 
 1.6.7 - 20190925

client/CMakeLists.txt

@@ -1,7 +1,4 @@
-include_directories(${mosquitto_SOURCE_DIR} ${mosquitto_SOURCE_DIR}/lib
+FIND_PACKAGE(cJSON)
-			${STDBOOL_H_PATH} ${STDINT_H_PATH} ${PTHREAD_INCLUDE_DIR}
-			${OPENSSL_INCLUDE_DIR})
-link_directories(${mosquitto_BINARY_DIR}/lib)
 
 set(shared_src client_shared.c client_shared.h client_props.c)
 
@@ -9,10 +6,32 @@ if (WITH_SRV)
 	add_definitions("-DWITH_SRV")
 endif (WITH_SRV)
 
+set( CLIENT_INC ${mosquitto_SOURCE_DIR} ${mosquitto_SOURCE_DIR}/lib
+            ${STDBOOL_H_PATH} ${STDINT_H_PATH} ${PTHREAD_INCLUDE_DIR}
+            ${OPENSSL_INCLUDE_DIR})
+
+set( CLIENT_DIR ${mosquitto_BINARY_DIR}/lib)
+
+if (CJSON_FOUND)
+	message(STATUS ${CJSON_FOUND})
+	set( CLIENT_DIR "${CLIENT_DIR} ${CJSON_DIR}" )
+	set( CLIENT_INC "${CLIENT_INC};${CJSON_INCLUDE_DIRS}" )
+	add_definitions("-DWITH_CJSON")
+endif()
+
+include_directories(${CLIENT_INC})
+link_directories(${CLIENT_DIR})
+
 add_executable(mosquitto_pub pub_client.c pub_shared.c ${shared_src})
 add_executable(mosquitto_sub sub_client.c sub_client_output.c ${shared_src})
 add_executable(mosquitto_rr rr_client.c pub_shared.c sub_client_output.c ${shared_src})
 
+if (CJSON_FOUND)
+	target_link_libraries(mosquitto_pub ${CJSON_LIBRARIES})
+	target_link_libraries(mosquitto_sub ${CJSON_LIBRARIES})
+	target_link_libraries(mosquitto_rr ${CJSON_LIBRARIES})
+endif()
+
 if (WITH_STATIC_LIBRARIES)
 	target_link_libraries(mosquitto_pub libmosquitto_static)
 	target_link_libraries(mosquitto_sub libmosquitto_static)

client/sub_client_output.c

@@ -30,6 +30,10 @@ Contributors:
 #define snprintf sprintf_s
 #endif
 
+#ifdef WITH_CJSON
+#  include <cJSON.h>
+#endif
+
 #ifdef __APPLE__
 #  include <sys/time.h>
 #endif
@@ -96,6 +100,7 @@ static void write_payload(const unsigned char *payload, int payloadlen, int hex)
 }
 
 
+#ifndef WITH_CJSON
 static void write_json_payload(const char *payload, int payloadlen)
 {
 	int i;
@@ -108,10 +113,91 @@ static void write_json_payload(const char *payload, int payloadlen)
 		}
 	}
 }
+#endif
 
 
-static void json_print(const struct mosquitto_message *message, const struct tm *ti, bool escaped)
+static int json_print(const struct mosquitto_message *message, const struct tm *ti, bool escaped)
 {
+#ifdef WITH_CJSON
+	cJSON *root;
+	cJSON *tmp;
+	char *json_str;
+	const char *return_parse_end;
+
+	root = cJSON_CreateObject();
+	if(root == NULL){
+		return MOSQ_ERR_NOMEM;
+	}
+
+	tmp = cJSON_CreateNumber(time(NULL));
+	if(tmp == NULL){
+		cJSON_Delete(root);
+		return MOSQ_ERR_NOMEM;
+	}
+	cJSON_AddItemToObject(root, "tst", tmp);
+
+	tmp = cJSON_CreateStringReference(message->topic);
+	if(tmp == NULL){
+		cJSON_Delete(root);
+		return MOSQ_ERR_NOMEM;
+	}
+
+	cJSON_AddItemToObject(root, "topic", tmp);
+
+	tmp = cJSON_CreateNumber(message->qos);
+	if(tmp == NULL){
+		cJSON_Delete(root);
+		return MOSQ_ERR_NOMEM;
+	}
+	cJSON_AddItemToObject(root, "qos", tmp);
+
+	tmp = cJSON_CreateNumber(message->retain);
+	if(tmp == NULL){
+		cJSON_Delete(root);
+		return MOSQ_ERR_NOMEM;
+	}
+	cJSON_AddItemToObject(root, "retain", tmp);
+
+	tmp = cJSON_CreateNumber(message->payloadlen);
+	if(tmp == NULL){
+		cJSON_Delete(root);
+		return MOSQ_ERR_NOMEM;
+	}
+	cJSON_AddItemToObject(root, "payloadlen", tmp);
+
+	if(message->qos > 0){
+		tmp = cJSON_CreateNumber(message->mid);
+		if(tmp == NULL){
+			cJSON_Delete(root);
+			return MOSQ_ERR_NOMEM;
+		}
+		cJSON_AddItemToObject(root, "mid", tmp);
+	}
+	if(escaped){
+		tmp = cJSON_CreateStringReference(message->payload);
+		if(tmp == NULL){
+			cJSON_Delete(root);
+			return MOSQ_ERR_NOMEM;
+		}
+		cJSON_AddItemToObject(root, "payload", tmp);
+	}else{
+		return_parse_end = NULL;
+		tmp = cJSON_ParseWithOpts(message->payload, &return_parse_end, true);
+		if(tmp == NULL || return_parse_end != message->payload + message->payloadlen){
+			cJSON_Delete(root);
+			return MOSQ_ERR_INVAL;
+		}
+		cJSON_AddItemToObject(root, "payload", tmp);
+	}
+
+	json_str = cJSON_PrintUnformatted(root);
+	cJSON_Delete(root);
+
+	fputs(json_str, stdout);
+	free(json_str);
+	
+	return MOSQ_ERR_SUCCESS;
+#else
 	char buf[100];
 
 	strftime(buf, 100, "%s", ti);
@@ -128,6 +214,9 @@ static void json_print(const struct mosquitto_message *message, const struct tm
 		write_payload(message->payload, message->payloadlen, 0);
 		fputs("}", stdout);
 	}
+	
+	return MOSQ_ERR_SUCCESS;
+#endif
 }
 
 
@@ -139,6 +228,7 @@ static void formatted_print(const struct mosq_config *lcfg, const struct mosquit
 	long ns;
 	char strf[3];
 	char buf[100];
+	int rc;
 
 	len = strlen(lcfg->format);
 
@@ -170,7 +260,10 @@ static void formatted_print(const struct mosq_config *lcfg, const struct mosquit
 								return;
 							}
 						}
-						json_print(message, ti, true);
+						if(json_print(message, ti, true) != MOSQ_ERR_SUCCESS){
+							err_printf(lcfg, "Error: Out of memory.\n");
+							return;
+						}
 						break;
 
 					case 'J':
@@ -180,7 +273,14 @@ static void formatted_print(const struct mosq_config *lcfg, const struct mosquit
 								return;
 							}
 						}
-						json_print(message, ti, false);
+						rc = json_print(message, ti, false);
+						if(rc == MOSQ_ERR_NOMEM){
+							err_printf(lcfg, "Error: Out of memory.\n");
+							return;
+						}else if(rc == MOSQ_ERR_INVAL){
+							err_printf(lcfg, "Error: Message payload is not valid JSON on topic %s.\n", message->topic);
+							return;
+						}
 						break;
 
 					case 'l':

cmake/FindcJSON.cmake

@@ -0,0 +1,39 @@
+INCLUDE( FindPackageHandleStandardArgs )
+
+# Checks an environment variable; note that the first check
+# does not require the usual CMake $-sign.
+IF( DEFINED ENV{CJSON_DIR} )
+	SET( CJSON_DIR "$ENV{CJSON_DIR}" )
+ENDIF()
+
+FIND_PATH(
+		CJSON_INCLUDE_DIR
+		cJSON.h
+	HINTS
+		CJSON_DIR
+		/usr/include/cjson
+)
+
+FIND_LIBRARY( CJSON_LIBRARY
+	NAMES cjson
+	HINTS ${CJSON_DIR}
+)
+
+FIND_PACKAGE_HANDLE_STANDARD_ARGS( CJSON DEFAULT_MSG
+	CJSON_INCLUDE_DIR CJSON_LIBRARY
+)
+
+IF( CJSON_FOUND )
+	SET( CJSON_INCLUDE_DIRS ${CJSON_INCLUDE_DIR} )
+	SET( CJSON_LIBRARIES ${CJSON_LIBRARY} )
+
+	MARK_AS_ADVANCED(
+		CJSON_LIBRARY
+		CJSON_INCLUDE_DIR
+		CJSON_DIR
+	)
+ELSE()
+	SET( CJSON_DIR "" CACHE STRING
+		"An optional hint to a directory for finding `cJSON`"
+	)
+ENDIF()

compiling.txt

@@ -4,7 +4,8 @@ are optional.
 * openssl
 * c-ares (for DNS-SRV support, disabled by default)
 * tcp-wrappers (optional, package name libwrap0-dev)
-* libwebsockets (optional, disabled by default, version 1.3 and above)
+* libwebsockets (optional, disabled by default, version 2.4 and above)
+* cJSON (optional, for JSON output from mosquitto_sub/mosquitto_rr)
 * On Windows, a pthreads library is required if threading support is to be
   included.
 

config.mk

@@ -100,6 +100,9 @@ WITH_COVERAGE:=no
 # Build with unix domain socket support
 WITH_UNIX_SOCKETS:=yes
 
+# Build mosquitto_sub with cJSON support
+WITH_CJSON:=yes
+
 # =============================================================================
 # End of user configuration
 # =============================================================================
@@ -321,3 +324,8 @@ ifeq ($(WITH_COVERAGE),yes)
 	CLIENT_CFLAGS:=$(CLIENT_CFLAGS) -coverage
 	CLIENT_LDFLAGS:=$(CLIENT_LDFLAGS) -coverage
 endif
+
+ifeq ($(WITH_CJSON),yes)
+	CLIENT_CFLAGS:=$(CLIENT_CFLAGS) -DWITH_CJSON -I/usr/include/cjson
+	CLIENT_LDADD:=$(CLIENT_LDADD) -lcjson
+endif

man/mosquitto_rr.1.xml

@@ -680,7 +680,9 @@
 						parameters and timestamp, with a non-quoted and
 						non-escaped payload - this means the payload must
 						itself be valid JSON. For example:
-						<code>{"tst":1470825369,"topic":"foo","qos":0,"retain":0,"payload":{"temperature":27.0,"humidity":57}}</code>.</para></listitem>
+						<code>{"tst":1470825369,"topic":"foo","qos":0,"retain":0,"payload":{"temperature":27.0,"humidity":57}}</code>.</para>
+					<para>If the payload is not valid JSON, then the error message "Error: Message payload is not valid JSON on topic
+						&lt;topic&gt;" will be printed to stderr.</para></listitem>
 				<listitem><para><option>%I</option> ISO-8601 format date and time, e.g. 2016-08-10T09:47:38+0100</para></listitem>
 				<listitem><para><option>%U</option> Unix timestamp with nanoseconds, e.g. 1470818943.786368637</para></listitem>
 			</itemizedlist>

man/mosquitto_sub.1.xml

@@ -797,7 +797,10 @@ mosquitto_sub -t 'bbc/#' -T bbc/bbc1 --remove-retained</programlisting>
 						parameters and timestamp, with a non-quoted and
 						non-escaped payload - this means the payload must
 						itself be valid JSON. For example:
-						<code>{"tst":1470825369,"topic":"foo","qos":0,"retain":0,"payload":{"temperature":27.0,"humidity":57}}</code>.</para></listitem>
+						<code>{"tst":1470825369,"topic":"foo","qos":0,"retain":0,"payload":{"temperature":27.0,"humidity":57}}</code>.</para>
+					<para>If the payload is not valid JSON, then the error message "Error: Message payload is not valid JSON on topic
+						&lt;topic&gt;" will be printed to stderr.</para></listitem>
+
 				<listitem><para><option>%I</option> ISO-8601 format date and time, e.g. 2016-08-10T09:47:38+0100</para></listitem>
 				<listitem><para><option>%U</option> Unix timestamp with nanoseconds, e.g. 1470818943.786368637</para></listitem>
 			</itemizedlist>

readme.md

@@ -71,6 +71,7 @@ already be built. Use `make binary` to skip building the man pages, or install
 * openssl (libssl-dev on Debian based systems) - disable with `make WITH_TLS=no`
 * xsltproc (xsltproc and docbook-xsl on Debian based systems) - only needed when building from git sources - disable with `make WITH_DOCS=no`
 * uthash / utlist - bundled versions of these headers are provided, disable their use with `make WITH_BUNDLED_DEPS=no`
+* cJSON - for client JSON output support. Disable with `make WITH_CJSON=no` Auto detected with CMake.
 
 Equivalent options for enabling/disabling features are available when using the CMake build.