STM32/W5500/MbedTLS Skip Verification and Connect to MQTT/8883 ?

[kenYuCh]

• My goal is: STM32/W5500/MbedTLS Skip Verification and Connect to MQTT/8883.

• My question is: How do I set skip_verifcation in Mongoosews to access MQTTS 8883 without authentication? I need to test my project in this environment. I can't connect successfully using either MG_TLS_MBED or MG_TLS_BUILTIN. (This is custom PCB board).

• The result I saw:

      931    2 mongoose.c:5131:mg_tcpip_poll  Status: down, IP: 0.0.0.0, rx:0, tx:0, dr:0, er:0
      93f    1 mongoose.c:5159:mg_tcpip_poll  Network is down
      d17    2 mongoose.c:5131:mg_tcpip_poll  Status: down, IP: 0.0.0.0, rx:0, tx:0, dr:0, er:0
      d25    1 mongoose.c:4386:onstatechange  Link up
      d35    3 mongoose.c:4499:tx_dhcp_discov DHCP discover sent. Our MAC: 02:04:0e:08:0d:06
      d85    3 mongoose.c:4478:tx_dhcp_reques DHCP req sent
      de3    2 mongoose.c:4621:rx_dhcp_client Lease: 86400 sec (86403)
      ded    1 mongoose.c:4383:onstatechange  Got IP
      e03    2 mongoose.c:4379:onstatechange  READY, IP: 192.168.0.171
      e0d    2 mongoose.c:4380:onstatechange         GW: 192.168.0.1
      e17    2 mongoose.c:4381:onstatechange        MAC: 02:04:0e:08:0d:06
  
      a18f   3 mongoose.c:4054:mg_connect_svc 5 -1 mqtts://test.mosquitto.org:8883
      MQTT_Timer_Fn Trigger
      a199   2 mongoose.c:5131:mg_tcpip_poll  Status: ready, IP: 192.168.0.171, rx:42, tx:20, dr:0, er:0
      a1ad   3 mongoose.c:299:dns_cb          5 test.mosquitto.org is 5.196.78.28
      a1b4   3 mongoose.c:5326:mg_connect_res 5 192.168.0.171:33799 -> 5.196.78.28:8883
      [MQTT] MG_EV_CONNECT
      [MQTT] TLS connection detected, initializing TLS…
      a2cb   3 mongoose.c:14147:mg_tls_init   5 Setting TLS
      TLS min/max: 3.3 - 3.3
      [TLS] automode verify none
      [TLS] setup success
      [MQTT TLS] Using Mongoose TLS with maximum compatibility (no SNI)
      a3dc   1 mongoose.c:502:mg_error        5 -1 TLS handshake: -0x7780
      [MQTT] 5 MG_EV_ERROR TLS handshake: -0x7780
      [MQTT TLS DIAGNOSIS] ================================
      [MQTT TLS] Error -0x7780: MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY
      [MQTT TLS] Server closed connection during handshake
      [MQTT TLS] Common causes:
      [MQTT TLS]   - TLS version mismatch (server expects different version)
      [MQTT TLS]   - Cipher suite incompatibility
      [MQTT TLS]   - Server doesn’t accept our TLS configuration
      [MQTT TLS]   - SNI hostname verification issue
      [MQTT TLS] Solutions to try:
      [MQTT TLS]   1. Disable SNI (set name to empty)
      [MQTT TLS]   2. Try different TLS versions
      [MQTT TLS]   3. Use non-encrypted connection first to test
      [MQTT TLS DIAGNOSIS] ================================
      [MQTT] MG_EV_CLOSE 5
      [MQTT TLS] TLS resources cleaned up
      a428   3 mongoose.c:4024:mg_close_conn  5 -1 closed
  

Environment

• mongoose version: 7.18
• Compiler/IDE and SDK: STM32CubeIDE 1.16.1 / STM32F401
• Target hardware/board: Custom
• Connectivity chip/module: STM32F401/W5500
• Target RTOS/OS (if applicable): FreeRTOS
• Lib: MbedTLS(2.16), Mongoosews 7.8

Config

#define MG_ARCH MG_ARCH_NEWLIB // MG_ARCH_ARMGCC, Plain ARM GCC
#define MG_TLS MG_TLS_MBED
#define MG_ENABLE_MIP 1
#define MG_ENABLE_TCPIP 1
#define MG_HTTP_INDEX "index.html" // default page, mongoose.h 977 lines
#define MG_ENABLE_CUSTOM_MILLIS 1
#define MG_ENABLE_CUSTOM_RANDOM 1
#define MG_ENABLE_TCPIP_PRINT_DEBUG_STATS 1 // Debug
#define MG_ENABLE_PACKED_FS 1
#define MG_ENABLE_FATFS 1
#define MG_ENABLE_POSIX_FS 0
#define MG_ENABLE_LOG 1
#define MG_ENABLE_DRIVER_W5500 1

Code

#define MQTT_URL "mqtts://test.mosquitto.org:8883"

void MQTTEvent(struct mg_connection *c, int ev, void ev_data) {
switch(ev) {
case MG_EV_CONNECT: {
struct mg_tls_opts mqtt_tls_opts = {0};
mqtt_tls_opts.ca = mg_str(""); // or not use
mqtt_tls_opts.skip_verification = 1;
mg_tls_init(c, &mqtt_tls_opts);
};
break;
}
}

void MQTT_Timer_Fn(void *arg) {
struct mg_mgr *mgr = (struct mg_mgr *) arg;
struct mg_mqtt_opts mqtt_opts;
memset(&mqtt_opts, 0, sizeof(mqtt_opts));
mqtt_opts.clean = true;
mqtt_opts.keepalive = 10;
mqtt_opts.version = 4;
mqtt_opts.pass = mg_str(MQTT_PASS);
mqtt_opts.user = mg_str(MQTT_USER);
if (s_mqtt_conn == NULL) {
s_mqtt_conn = mg_mqtt_connect(mgr, MQTT_URL, &mqtt_opts, MQTTEvent, NULL);
} else {
mg_mqtt_ping(s_mqtt_conn);
};
printf("MQTT_Timer_Fn Trigger\n");
}