net/mqtt: Remove length computations for some msg fields

Currently, for the following MQTT msg fields:

- client_id
- will_topic
- user_name
- topic

their length is computed inside the routine that receives the MQTT msg.

Although this simplifies development, also imposes one restriction:
data must be null-terminated. Sometimes, data is received from other
sources and not generated by the application, so the null-terminated
constraint may be considered problematic for the user.

This patch removes the assumption that string fields are null-terminated.
Current data structures are already prepared to handle this case, so no
API change is required.

Change-Id: I5a147a5b21e0da49541cbe62baac363c8737cd3e
Signed-off-by: Flavio Santes <flavio.santes@intel.com>

4 files changed, 56 insertions, 24 deletions

diff --git a/include/net/mqtt_types.h b/include/net/mqtt_types.h
index 9bf275ef4..adc988563 100644
--- a/include/net/mqtt_types.h
+++ b/include/net/mqtt_types.h
@@ -56,7 +56,7 @@ enum mqtt_qos {
 struct mqtt_connect_msg {
 	uint8_t clean_session:1;
 	char *client_id;
-	uint16_t client_id_len;	/* only required for unpacking */
+	uint16_t client_id_len;
 	uint8_t will_flag:1;
 	enum mqtt_qos will_qos;
 	uint8_t will_retain:1;
@@ -66,7 +66,7 @@ struct mqtt_connect_msg {
 	uint16_t will_msg_len;
 	uint16_t keep_alive;
 	const char *user_name;
-	uint16_t user_name_len;	/*only required for unpacking */
+	uint16_t user_name_len;
 	uint8_t *password;
 	uint16_t password_len;
 };
diff --git a/samples/net/mqtt_publisher/src/main.c b/samples/net/mqtt_publisher/src/main.c
index ce7289bb2..3b485b5bf 100644
--- a/samples/net/mqtt_publisher/src/main.c
+++ b/samples/net/mqtt_publisher/src/main.c
@@ -22,6 +22,8 @@
 
 #include "config.h"
 
+#define CLIENTID "zephyr_publisher"
+
 /**
  * @brief mqtt_client_ctx	Container of some structures used by the
  *				publisher app.
@@ -272,7 +274,8 @@ void publisher(void)
 	 * will be set to 0 also. Please don't do that, set always to 1.
 	 * Clean session = 0 is not yet supported.
 	 */
-	client_ctx.connect_msg.client_id = "zephyr_publisher";
+	client_ctx.connect_msg.client_id = CLIENTID;
+	client_ctx.connect_msg.client_id_len = strlen(CLIENTID);
 	client_ctx.connect_msg.clean_session = 1;
 
 	client_ctx.connect_data = "CONNECTED";
diff --git a/subsys/net/lib/mqtt/mqtt_pkt.c b/subsys/net/lib/mqtt/mqtt_pkt.c
index 589ee4566..08cf82f5a 100644
--- a/subsys/net/lib/mqtt/mqtt_pkt.c
+++ b/subsys/net/lib/mqtt/mqtt_pkt.c
@@ -299,14 +299,12 @@ int mqtt_pack_connect(uint8_t *buf, uint16_t *length, uint16_t size,
 
 	/* client_id				*/
 	pkt_size = INT_SIZE;
-	msg->client_id_len = mqtt_strlen(msg->client_id);
 	pkt_size += msg->client_id_len;
 
 	/* will flag - optional			*/
 	if (msg->will_flag) {
 		/* will topic			*/
 		pkt_size += INT_SIZE;
-		msg->will_topic_len = mqtt_strlen(msg->will_topic);
 		pkt_size += msg->will_topic_len;
 		/* will message - binary	*/
 		pkt_size += INT_SIZE;
@@ -316,7 +314,6 @@ int mqtt_pack_connect(uint8_t *buf, uint16_t *length, uint16_t size,
 	/* user_name - UTF-8 - optional		*/
 	if (msg->user_name) {
 		pkt_size += INT_SIZE;
-		msg->user_name_len = mqtt_strlen(msg->user_name);
 		pkt_size += msg->user_name_len;
 	}
 
@@ -850,7 +847,6 @@ int mqtt_pack_publish(uint8_t *buf, uint16_t *length, uint16_t size,
 		return -EINVAL;
 	}
 
-	msg->topic_len = mqtt_strlen(msg->topic);
 	/* Packet Identifier is only included if QoS > QoS0. See MQTT 3.3.2.2
 	 * So, payload size is:
 	 * topic length size + topic length + packet id + msg's size
diff --git a/tests/net/lib/mqtt_packet/src/mqtt_packet.c b/tests/net/lib/mqtt_packet/src/mqtt_packet.c
index fc8e982d5..fd58ae92a 100644
--- a/tests/net/lib/mqtt_packet/src/mqtt_packet.c
+++ b/tests/net/lib/mqtt_packet/src/mqtt_packet.c
@@ -10,6 +10,15 @@
 
 #define RC_STR(rc)	(rc == TC_PASS ? PASS : FAIL)
 
+#define CLIENTID	"zephyr"
+#define CLIENTID_LEN	6
+#define TOPIC		"sensors"
+#define TOPIC_LEN	7
+#define WILL_TOPIC	"quitting"
+#define WILL_TOPIC_LEN	8
+#define USERNAME	"zephyr1"
+#define USERNAME_LEN	7
+
 /* MQTT messages in this test are under 256 bytes */
 #define BUF_SIZE	256
 static uint8_t buf[BUF_SIZE];
@@ -220,7 +229,9 @@ uint8_t connect1[] = {0x10, 0x12, 0x00, 0x04, 0x4d, 0x51, 0x54, 0x54,
 		      0x70, 0x68, 0x79, 0x72};
 
 static struct mqtt_connect_msg msg_connect1 = {
-	.clean_session = 1, .client_id = "zephyr", .will_flag = 0,
+	.clean_session = 1, .client_id = CLIENTID,
+	.client_id_len = CLIENTID_LEN,
+	.will_flag = 0,
 	.will_qos = 0, .will_retain = 0, .will_topic = NULL,
 	.will_msg = NULL, .will_msg_len = 0,
 	.keep_alive = 0, .user_name = NULL,
@@ -240,7 +251,9 @@ uint8_t connect2[] = {0x10, 0x12, 0x00, 0x04, 0x4d, 0x51, 0x54, 0x54,
 		      0x70, 0x68, 0x79, 0x72};
 
 static struct mqtt_connect_msg msg_connect2 = {
-	.clean_session = 1, .client_id = "zephyr", .will_flag = 0,
+	.clean_session = 1, .client_id = CLIENTID,
+	.client_id_len = CLIENTID_LEN,
+	.will_flag = 0,
 	.will_qos = 0, .will_retain = 0, .will_topic = NULL,
 	.will_msg = NULL, .will_msg_len = 0,
 	.keep_alive = 365, .user_name = NULL,
@@ -265,8 +278,11 @@ uint8_t connect3[] = {0x10, 0x21, 0x00, 0x04, 0x4d, 0x51, 0x54, 0x54,
 		      0x62, 0x79, 0x65};
 
 static struct mqtt_connect_msg msg_connect3 = {
-	.clean_session = 1, .client_id = "zephyr", .will_flag = 1,
-	.will_qos = 0, .will_retain = 0, .will_topic = "quitting",
+	.clean_session = 1, .client_id = CLIENTID,
+	.client_id_len = CLIENTID_LEN,
+	.will_flag = 1,
+	.will_qos = 0, .will_retain = 0, .will_topic = WILL_TOPIC,
+	.will_topic_len = WILL_TOPIC_LEN,
 	.will_msg = "bye", .will_msg_len = 3,
 	.keep_alive = 0, .user_name = NULL,
 	.password = NULL, .password_len = 0
@@ -288,8 +304,11 @@ uint8_t connect4[] = {0x10, 0x21, 0x00, 0x04, 0x4d, 0x51, 0x54, 0x54,
 		      0x62, 0x79, 0x65};
 
 static struct mqtt_connect_msg msg_connect4 = {
-	.clean_session = 1, .client_id = "zephyr", .will_flag = 1,
-	.will_qos = 0, .will_retain = 1, .will_topic = "quitting",
+	.clean_session = 1, .client_id = CLIENTID,
+	.client_id_len = CLIENTID_LEN,
+	.will_flag = 1,
+	.will_qos = 0, .will_retain = 1, .will_topic = WILL_TOPIC,
+	.will_topic_len = WILL_TOPIC_LEN,
 	.will_msg = "bye", .will_msg_len = 3,
 	.keep_alive = 0, .user_name = NULL,
 	.password = NULL, .password_len = 0
@@ -311,8 +330,11 @@ uint8_t connect5[] = {0x10, 0x21, 0x00, 0x04, 0x4d, 0x51, 0x54, 0x54,
 		      0x62, 0x79, 0x65};
 
 static struct mqtt_connect_msg msg_connect5 = {
-	.clean_session = 1, .client_id = "zephyr", .will_flag = 1,
-	.will_qos = 1, .will_retain = 0, .will_topic = "quitting",
+	.clean_session = 1, .client_id = CLIENTID,
+	.client_id_len = CLIENTID_LEN,
+	.will_flag = 1,
+	.will_qos = 1, .will_retain = 0, .will_topic = WILL_TOPIC,
+	.will_topic_len = WILL_TOPIC_LEN,
 	.will_msg = "bye", .will_msg_len = 3,
 	.keep_alive = 0, .user_name = NULL,
 	.password = NULL, .password_len = 0
@@ -334,8 +356,11 @@ uint8_t connect6[] = {0x10, 0x21, 0x00, 0x04, 0x4d, 0x51, 0x54, 0x54,
 		      0x62, 0x79, 0x65};
 
 static struct mqtt_connect_msg msg_connect6 = {
-	.clean_session = 1, .client_id = "zephyr", .will_flag = 1,
-	.will_qos = 1, .will_retain = 1, .will_topic = "quitting",
+	.clean_session = 1, .client_id = CLIENTID,
+	.client_id_len = CLIENTID_LEN,
+	.will_flag = 1,
+	.will_qos = 1, .will_retain = 1, .will_topic = WILL_TOPIC,
+	.will_topic_len = WILL_TOPIC_LEN,
 	.will_msg = "bye", .will_msg_len = 3,
 	.keep_alive = 0, .user_name = NULL,
 	.password = NULL, .password_len = 0
@@ -360,10 +385,14 @@ uint8_t connect7[] = {0x10, 0x34, 0x00, 0x04, 0x4d, 0x51, 0x54, 0x54,
 		      0x73, 0x73, 0x77, 0x6f, 0x72, 0x64};
 
 static struct mqtt_connect_msg msg_connect7 = {
-	.clean_session = 1, .client_id = "zephyr", .will_flag = 1,
-	.will_qos = 1, .will_retain = 1, .will_topic = "quitting",
+	.clean_session = 1, .client_id = CLIENTID,
+	.client_id_len = CLIENTID_LEN,
+	.will_flag = 1,
+	.will_qos = 1, .will_retain = 1, .will_topic = WILL_TOPIC,
+	.will_topic_len = WILL_TOPIC_LEN,
 	.will_msg = "bye", .will_msg_len = 3,
-	.keep_alive = 0, .user_name = "zephyr1",
+	.keep_alive = 0, .user_name = USERNAME,
+	.user_name_len = USERNAME_LEN,
 	.password = "password", .password_len = 8
 };
 
@@ -382,7 +411,8 @@ uint8_t publish1[] = {0x30, 0x0b, 0x00, 0x07, 0x73, 0x65, 0x6e, 0x73,
 		      0x6f, 0x72, 0x73, 0x4f, 0x4b};
 
 static struct mqtt_publish_msg msg_publish1 = {
-	.dup = 0, .qos = 0, .retain = 0, .topic = "sensors",
+	.dup = 0, .qos = 0, .retain = 0, .topic = TOPIC,
+	.topic_len = TOPIC_LEN,
 	.pkt_id = 0, .msg = "OK", .msg_len = 2,
 };
 
@@ -398,7 +428,8 @@ uint8_t publish2[] = {0x31, 0x0b, 0x00, 0x07, 0x73, 0x65, 0x6e, 0x73,
 		      0x6f, 0x72, 0x73, 0x4f, 0x4b};
 
 static struct mqtt_publish_msg msg_publish2 = {
-	.dup = 0, .qos = 0, .retain = 1, .topic = "sensors",
+	.dup = 0, .qos = 0, .retain = 1, .topic = TOPIC,
+	.topic_len = TOPIC_LEN,
 	.pkt_id = 0, .msg = "OK", .msg_len = 2
 };
 
@@ -414,7 +445,8 @@ uint8_t publish3[] = {0x33, 0x0d, 0x00, 0x07, 0x73, 0x65, 0x6e, 0x73,
 		      0x6f, 0x72, 0x73, 0x00, 0x01, 0x4f, 0x4b};
 
 static struct mqtt_publish_msg msg_publish3 = {
-	.dup = 0, .qos = 1, .retain = 1, .topic = "sensors",
+	.dup = 0, .qos = 1, .retain = 1, .topic = TOPIC,
+	.topic_len = TOPIC_LEN,
 	.pkt_id = 1, .msg = "OK", .msg_len = 2
 };
 
@@ -429,7 +461,8 @@ static
 uint8_t publish4[] = {0x34, 0x0d, 0x00, 0x07, 0x73, 0x65, 0x6e, 0x73,
 		      0x6f, 0x72, 0x73, 0x00, 0x01, 0x4f, 0x4b};
 static struct mqtt_publish_msg msg_publish4 = {
-	.dup = 0, .qos = 2, .retain = 0, .topic = "sensors",
+	.dup = 0, .qos = 2, .retain = 0, .topic = TOPIC,
+	.topic_len = TOPIC_LEN,
 	.pkt_id = 1, .msg = "OK", .msg_len = 2
 };