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91 lines
3.4 KiB
C
91 lines
3.4 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 MQTT server specified by `s_url` variable
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// 2. When connected, subscribes to the topic `s_sub_topic`
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// 3. Publishes message `hello` to the `s_pub_topic`
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// 4. Receives that message back from the subscribed topic and closes
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// 5. Timer-based reconnection logic revives the connection when it is down
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//
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// To enable SSL/TLS for this client, build it like this:
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// make MBEDTLS_DIR=/path/to/your/mbedtls/installation
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#include "mongoose.h"
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static const char *s_url = "mqtt://broker.hivemq.com:1883";
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static const char *s_sub_topic = "mg/+/test";
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static const char *s_pub_topic = "mg/clnt/test";
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static int s_qos = 1;
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static struct mg_connection *s_conn;
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// Handle interrupts, like Ctrl-C
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static int s_signo;
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static void signal_handler(int signo) {
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s_signo = signo;
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}
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static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
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if (ev == MG_EV_OPEN) {
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LOG(LL_INFO, ("CREATED"));
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// c->is_hexdumping = 1;
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} else if (ev == MG_EV_ERROR) {
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// On error, log error message
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LOG(LL_ERROR, ("%p %s", c->fd, (char *) ev_data));
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} else if (ev == MG_EV_CONNECT) {
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// If target URL is SSL/TLS, command client connection to use TLS
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if (mg_url_is_ssl(s_url)) {
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struct mg_tls_opts opts = {.ca = "ca.pem"};
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mg_tls_init(c, &opts);
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}
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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 subt = mg_str(s_sub_topic);
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struct mg_str pubt = mg_str(s_pub_topic), data = mg_str("hello");
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LOG(LL_INFO, ("CONNECTED to %s", s_url));
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mg_mqtt_sub(c, subt, s_qos);
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LOG(LL_INFO, ("SUBSCRIBED to %.*s", (int) subt.len, subt.ptr));
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mg_mqtt_pub(c, pubt, data, s_qos, false);
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LOG(LL_INFO, ("PUBSLISHED %.*s -> %.*s", (int) data.len, data.ptr,
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(int) pubt.len, pubt.ptr));
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} else if (ev == MG_EV_MQTT_MSG) {
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// When we get echo response, print it
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struct mg_mqtt_message *mm = (struct mg_mqtt_message *) ev_data;
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LOG(LL_INFO, ("RECEIVED %.*s <- %.*s", (int) mm->data.len, mm->data.ptr,
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(int) mm->topic.len, mm->topic.ptr));
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c->is_closing = 1;
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} else if (ev == MG_EV_CLOSE) {
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LOG(LL_INFO, ("CLOSED"));
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s_conn = NULL; // Mark that we're closed
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}
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(void) fn_data;
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}
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// Timer function - recreate client connection if it is closed
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static void timer_fn(void *arg) {
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struct mg_mgr *mgr = (struct mg_mgr *) arg;
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struct mg_mqtt_opts opts = {.clean = true,
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.will_qos = s_qos,
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.will_topic = mg_str(s_pub_topic),
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.will_message = mg_str("goodbye")};
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if (s_conn == NULL) s_conn = mg_mqtt_connect(mgr, s_url, &opts, fn, NULL);
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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_timer timer;
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int topts = MG_TIMER_REPEAT | MG_TIMER_RUN_NOW;
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signal(SIGINT, signal_handler); // Setup signal handlers - exist event
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signal(SIGTERM, signal_handler); // manager loop on SIGINT and SIGTERM
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mg_mgr_init(&mgr); // Init event manager
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mg_timer_init(&timer, 3000, topts, timer_fn, &mgr); // Init timer
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while (s_signo == 0) mg_mgr_poll(&mgr, 1000); // Event loop, 1s timeout
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mg_mgr_free(&mgr); // Finished, cleanup
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mg_timer_free(&timer); // Free timer resources
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return 0;
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}
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