MQTT over SSL
Overview
This example connects to the broker URI by using MQTT SSL and as a demonstration subscribes/unsubscribes and send a message on certain topic. (Please note that the public broker is maintained by the community so may not be always available, for details please see this disclaimer)
PEM certificate for this example could be extracted from an openssl s_client command connecting to mqtt.eclipseprojects.io.
In case a host operating system has openssl and sed packages installed, one could execute the following command to download and save the root certificate to a file (Note for Windows users: Both Linux like environment or Windows native packages may be used).
echo "" | openssl s_client -showcerts -connect mqtt.eclipseprojects.io:8883 | sed -n "1,/Root/d; /BEGIN/,/END/p" | openssl x509 -outform PEM >mqtt_eclipseprojects_io.pem
Please note that this is not a general command for downloading a root certificate for an arbitrary host; this command works with mqtt.eclipseprojects.io as the site provides root certificate in the chain, which then could be extracted with text operation.
Requirements
A working AP is required.
Configure WiFi SSID and WiFi Password in menuconfig.
Configure the Broker URL in menuconfig.
A PEM certificate is required. It defaults to mian/src/mqtt_eclipseprojects_io.pem.
Building and Flashing
Example Location： examples/network/mqtt/ssl
For operations such as compiling and burning, please refer to: Quick Start Guide
Running Result
Upon successful execution, it will output the following logs
I/wm_nm_core [4.992] got ip: 192.168.3.208
D/wm_nm_core [4.998] WM_NM_EV post event 4 success
I/mqtt example [5.002] wifi station start success, network is ready!
D/mqtt [5.008] uri: ssl://mqtt.eclipseprojects.io:8883
D/mqtt [5.016] mqtt_config mode: 0
D/mqtt [5.020] ======================================
D/mqtt [5.026] Trace Output
D/mqtt [5.028] se Paho Synchronous MQTT C Client Library
D/mqtt [5.034] se Paho Synchronous MQTT C Client Library
D/mqtt [5.040] 17
D/mqtt [5.044] ======================================
D/mqtt [5.706] connect out: rc=119
D/mqtt [5.710] wait connect, timeout: 29340
D/mqtt [6.020] wait end
E/mqtt [6.024] client W800_29315F, packet_type 1, timeout 29340, pack 0x0
> Seeding the random number generator...
ok
> Loading the CA root certificate ...
CA root certificate is null.
ok
> Loading the client cert. and key...
Client certificate is null.
Client privateKey is null.
> Setting up the SSL/TLS structure...
ok
> Performing the SSL/TLS handshake...
ok
SSLSocket_putdatas: mbedtls_ssl_write rc 27, iov_len 27
D/mqtt [8.430] wait connect ack, timeout: 26620
D/mqtt [8.692] wait end
E/mqtt [8.696] client W800_29315F, packet_type 2, timeout 26620, pack 0x0
D/mqtt [8.706] MQTTClient connected!
I/mqtt example [8.710] mqtt connected
D/mqtt [8.714] mqtt client publish, topic /topic/qos1
SSLSocket_putdatas: mbedtls_ssl_write rc 23, iov_len 23
D/mqtt [8.730] mqtt client publish, token: 1
I/mqtt example [8.734] sent publish successful, msg_id=1
D/mqtt [8.740] mqtt client subscribe, topic /topic/qos0, qos 0
SSLSocket_putdatas: mbedtls_ssl_write rc 18, iov_len 18
D/mqtt [8.754] wait sub ack, timeout: 10000
D/mqtt [8.994] Message with token value 1 delivery confirmed
D/mqtt [9.252] wait end
E/mqtt [9.256] client W800_29315F, packet_type 9, timeout 10000, pack 0x0
I/mqtt example [9.264] sent subscribe successful, msg_id=2
D/mqtt [9.270] mqtt client subscribe, topic /topic/qos1, qos 1
SSLSocket_putdatas: mbedtls_ssl_write rc 18, iov_len 18
D/mqtt [9.286] wait sub ack, timeout: 10000
D/mqtt [9.548] wait end
E/mqtt [9.550] client W800_29315F, packet_type 9, timeout 10000, pack 0x0
I/mqtt example [9.558] sent subscribe successful, msg_id=3
D/mqtt [9.564] mqtt client unsubscribe, topic /topic/qos1
SSLSocket_putdatas: mbedtls_ssl_write rc 17, iov_len 17
D/mqtt [9.580] wait unsub ack, timeout: 10000
D/mqtt [9.838] wait end
E/mqtt [9.842] client W800_29315F, packet_type 11, timeout 10000, pack 0x0
I/mqtt example [9.850] sent unsubscribe successful, msg_id=4
I/mqtt example [9.854] mqtt published, msg_id=1
SSLSocket_putdatas: mbedtls_ssl_write rc 2, iov_len 2
SSLSocket_putdatas: mbedtls_ssl_write rc 2, iov_len 2
SSLSocket_putdatas: mbedtls_ssl_write rc 2, iov_len 2
D/mqtt [208.546] Message arrived, topic [/topic/qos0], paload [data{a]
I/mqtt example [208.554] mqtt recved data