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102 lines
3.9 KiB
C
102 lines
3.9 KiB
C
// Copyright (c) 2020 Cesanta Software Limited
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// All rights reserved
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//
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// Example MQTT client. It performs the following steps:
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// 1. Connects to the AWS IoT MQTT server
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// 2. When connected, subscribes to the topic `s_rx_topic`
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// 3. Publishes message `hello` to the `s_tx_topic` periodically
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//
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// This example requires TLS support. By default, it is built with mbedTLS,
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// therefore make sure mbedTLS is installed. To build with OpenSSL, execute:
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// make clean all CFLAGS="-W -Wall -DMG_ENABLE_OPENSSL=1 -lssl"
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// In order to get MQTT URL, login to AWS IoT, click on "Settings" on the left
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// bar, copy the "Endpoint" URL.
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static const char *s_url =
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"mqtts://a1pjwh2bop1ojt-ats.iot.eu-west-1.amazonaws.com";
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// To create certificates:
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// 1. Click Policies -> Create, fill fields:
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// Name : Policy1
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// Action : iot:*
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// Resource ARN: *
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// Effect : allow
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// then, click "Create"
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// 2. Click Manage -> Things -> Create things -> Create single thing -> Next
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// Thing name: t1, no shadow, Next
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// Auto-generate new certificate, Next
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// Select policy Policy1, Create thing
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// 3. From the dialog box that appears, download:
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// xxx-certificate.pem.crt as cert.pem to the example directory
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// xxx-private.pem.key as key.pem to the example directory
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// static const char *s_cert = "cert.pem";
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// static const char *s_key = "key.pem";
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static const char *s_rx_topic = "d/rx";
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static const char *s_tx_topic = "d/tx";
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static int s_qos = 1;
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#include "mongoose.h"
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static void fn(struct mg_connection *c, int ev, void *ev_data) {
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if (ev == MG_EV_OPEN) {
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// c->is_hexdumping = 1;
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} else if (ev == MG_EV_CONNECT) {
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if (mg_url_is_ssl(s_url)) {
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struct mg_tls_opts opts = {.ca = mg_unpacked("/certs/ca.pem"),
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.name = mg_url_host(s_url)};
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mg_tls_init(c, &opts);
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}
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} else if (ev == MG_EV_ERROR) {
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// On error, log error message
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MG_ERROR(("%p %s", c->fd, (char *) ev_data));
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} else if (ev == MG_EV_MQTT_OPEN) {
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// MQTT connect is successful
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struct mg_str topic = mg_str(s_rx_topic);
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MG_INFO(("Connected to %s", s_url));
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MG_INFO(("Subscribing to %s", s_rx_topic));
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struct mg_mqtt_opts sub_opts;
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memset(&sub_opts, 0, sizeof(sub_opts));
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sub_opts.topic = topic;
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sub_opts.qos = s_qos;
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mg_mqtt_sub(c, &sub_opts);
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c->data[0] = 'X'; // Set a label that we're logged in
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} else if (ev == MG_EV_MQTT_MSG) {
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// When we receive MQTT message, print it
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struct mg_mqtt_message *mm = (struct mg_mqtt_message *) ev_data;
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MG_INFO(("Received on %.*s : %.*s", (int) mm->topic.len, mm->topic.ptr,
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(int) mm->data.len, mm->data.ptr));
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} else if (ev == MG_EV_POLL && c->data[0] == 'X') {
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static unsigned long prev_second;
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unsigned long now_second = (*(unsigned long *) ev_data) / 1000;
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if (now_second != prev_second) {
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struct mg_str topic = mg_str(s_tx_topic), data = mg_str("{\"a\":123}");
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MG_INFO(("Publishing to %s", s_tx_topic));
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struct mg_mqtt_opts pub_opts;
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memset(&pub_opts, 0, sizeof(pub_opts));
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pub_opts.topic = topic;
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pub_opts.message = data;
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pub_opts.qos = s_qos, pub_opts.retain = false;
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mg_mqtt_pub(c, &pub_opts);
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prev_second = now_second;
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}
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}
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if (ev == MG_EV_ERROR || ev == MG_EV_CLOSE) {
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MG_INFO(("Got event %d, stopping...", ev));
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*(bool *) c->fn_data = true; // Signal that we're done
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}
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}
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int main(void) {
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struct mg_mgr mgr;
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struct mg_mqtt_opts opts = {.clean = true};
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bool done = false;
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mg_mgr_init(&mgr); // Initialise event manager
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MG_INFO(("Connecting to %s", s_url)); // Inform that we're starting
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mg_mqtt_connect(&mgr, s_url, &opts, fn, &done); // Create client connection
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while (!done) mg_mgr_poll(&mgr, 1000); // Loop until done
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mg_mgr_free(&mgr); // Finished, cleanup
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return 0;
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}
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