MQTT - Cannot connect to broker when using username and PW

Question

Hi, I use the following. 
 
 Raspberry Pi 3 (RPi3 with Raspbian Jessie 4.4) as a router, 
 
 RPi3 is connected to a Wi-Fi router to access the Internet by using the built-in Wi-Fi BLE BCM43438 chip. 
 
 
 IoT SDK 0.9 (nrf5_iot_sdk_3288530) 
 
 
 MQTT Publisher Example, configured as the non-secure port 
 
 
 PCA10040 v1.1.0 (2016.23) 
 
 
 Keil MDK-ARM uVision 5.20 (in Windows 10 64bit) 
 
 
 
 
 
 Amazon EC2 (which uses Ubuntu 14.0) for Mosquitto Broker (v 1.4.9) 
 
 
 Amazon RDS which uses MySQL 5.6 for ACL (Access Control Lists) 
 
 
 Thanks to Stian's answer ,I tested the example and published the LED state. 
 Now I added Access Control Lists (ACL) by referring this blog. 
 I inserted username "user1" with password "1234" for testing. This user had read/write control. 
 I tested with Android Paho MQTT client Example ; the client who has the username and password above can only publish or subscribe. 
 Other users who had different username was disconnected when they tried to publish something. 
 /++++++++++++++++++++++++++++++++++++++++++++++++++++++++++/ 
 I entered the username and password. I modified the code like this; 
 #define APP_MQTT_BROKER_PORT 1883 /*8883*/ 
static void button_event_handler(uint8_t pin_no, uint8_t button_action){ // omitted some parts
 case BSP_BUTTON_0:{ if (m_connection_state == false){
 mqtt_client_init(&m_app_mqtt_client);

 mqtt_utf8_t pw = {"1234", 0};
 mqtt_utf8_t user = {"user1", 0};
 pw.utf_strlen = strlen(pw.p_utf_str);
 user.utf_strlen = strlen(user.p_utf_str);

 memcpy(m_app_mqtt_client.broker_addr.u8, m_broker_addr.u8, IPV6_ADDR_SIZE);
 m_app_mqtt_client.broker_port = APP_MQTT_BROKER_PORT;
 m_app_mqtt_client.evt_cb = app_mqtt_evt_handler;
 m_app_mqtt_client.client_id.p_utf_str = (uint8_t *)m_client_id;
 m_app_mqtt_client.client_id.utf_strlen = strlen(m_client_id);
 m_app_mqtt_client.p_password = &pw /*NULL*/;
 m_app_mqtt_client.p_user_name = &user /*NULL*/;
 m_app_mqtt_client.transport_type = MQTT_TRANSPORT_NON_SECURE /* MQTT_TRANSPORT_SECURE*/;
 m_app_mqtt_client.p_security_settings = NULL /*&m_tls_keys*/;

 uint32_t err_code = mqtt_connect(&m_app_mqtt_client);
 if(err_code || &(m_app_mqtt_client.p_password) == NULL) // breakpoint location
 APP_ERROR_CHECK(err_code);
 
 
 I placed a breakpoint at if(err_code) statement. 
 
 Although it returns no error, the PCA10040 cannot connect to the broker; the LED doesn't change to LED 2 on mode. 
 
 I sniffed the bt0 interface. You can see the packets in detail; wire-wPWCap.pcapng 
 Don't have a clue why destination port 0 is captured. 
 Did anybody test the MQTT example with ACL? 
 What seems to be the reason for failing connection after using ACL? 
 -Best Regards, Mango

Stian Røed Hafskjold · Accepted Answer

Hi, the problem is how you declare and define the mqtt_utf8_t pw and user variables, and also the strings within them. Remember that you pass the pointers to the m_app_mqtt_client varable, so when the function returns they will no longer be valid. You should declare them as global variables at the top of main.c . Something like this should work: 
 static uint8_t username[] = "test";
static uint8_t password[] = "test";
static mqtt_utf8_t pw;
static mqtt_utf8_t user;
 
 And then in button_event_handler() you can assign the values: 
 pw.p_utf_str = password;
pw.utf_strlen = strlen(password);
user.p_utf_str = username;
user.utf_strlen = strlen(username);
 
 And pass the pointers m_app_mqtt_client : 
 m_app_mqtt_client.p_password = &pw;
m_app_mqtt_client.p_user_name = &user;
 
 PS. I also tried with Mosquitto and the Auth plugin, and I got it working by following the guide you linked to. Just remember to get the apostrophes right ('%s') if you are copy/pasting the /etc/mosquitto/mosquitto.conf example directly. I also had to do the fix described here: github.com/.../33

MQTT - Cannot connect to broker when using username and PW

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