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>

1 files changed, 4 insertions, 1 deletions

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";