mongoose/examples/mqtt-over-ws-client/main.c

106 lines
4.0 KiB
C

// Copyright (c) 2020 Cesanta Software Limited
// All rights reserved
//
// Example MQTT client. It performs the following steps:
// 1. Connects to the MQTT server specified by `s_url` variable
// 2. When connected, subscribes to the topic `s_topic`
// 3. Publishes message `hello` to the `s_topic`
// 4. Receives that message back from the subscribed topic and exits
//
// To enable SSL/TLS, see https://mongoose.ws/tutorials/tls/#how-to-build
#include "mongoose.h"
static const char *s_url =
#if MG_TLS
"wss://broker.hivemq.com:8884/mqtt";
#else
"ws://broker.hivemq.com:8000/mqtt";
#endif
static const char *s_topic = "mg/test";
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_ERROR) {
// On error, log error message
MG_ERROR(("%p %s", c->fd, (char *) ev_data));
} else if (ev == MG_EV_CONNECT) {
if (mg_url_is_ssl(s_url)) {
struct mg_tls_opts opts = {.ca = mg_unpacked("/certs/ca.pem"),
.name = mg_url_host(s_url)};
mg_tls_init(c, &opts);
}
} else if (ev == MG_EV_WS_OPEN) {
// WS connection established. Perform MQTT login
MG_INFO(("Connected to WS. Logging in to MQTT..."));
struct mg_mqtt_opts opts = {
.qos = 1, .topic = mg_str(s_topic), .message = mg_str("goodbye")};
size_t len = c->send.len;
mg_mqtt_login(c, &opts);
mg_ws_wrap(c, c->send.len - len, WEBSOCKET_OP_BINARY);
c->is_hexdumping = 1;
} else if (ev == MG_EV_WS_MSG) {
struct mg_mqtt_message mm;
struct mg_ws_message *wm = (struct mg_ws_message *) ev_data;
uint8_t version = c->is_mqtt5 ? 5 : 4;
MG_INFO(("GOT %d bytes WS msg", (int) wm->data.len));
while ((mg_mqtt_parse((uint8_t *) wm->data.ptr, wm->data.len, version,
&mm)) == MQTT_OK) {
switch (mm.cmd) {
case MQTT_CMD_CONNACK:
mg_call(c, MG_EV_MQTT_OPEN, &mm.ack);
if (mm.ack == 0) {
struct mg_str topic = mg_str(s_topic), data = mg_str("hello");
size_t len = c->send.len;
MG_INFO(("CONNECTED to %s", s_url));
struct mg_mqtt_opts sub_opts;
memset(&sub_opts, 0, sizeof(sub_opts));
sub_opts.topic = topic;
sub_opts.qos = 1;
mg_mqtt_sub(c, &sub_opts);
len = mg_ws_wrap(c, c->send.len - len, WEBSOCKET_OP_BINARY);
MG_INFO(("SUBSCRIBED to %.*s", (int) topic.len, topic.ptr));
struct mg_mqtt_opts pub_opts;
memset(&pub_opts, 0, sizeof(pub_opts));
pub_opts.topic = topic;
pub_opts.message = data;
pub_opts.qos = 1, pub_opts.retain = false;
mg_mqtt_pub(c, &pub_opts);
MG_INFO(("PUBLISHED %.*s -> %.*s", (int) data.len, data.ptr,
(int) topic.len, topic.ptr));
len = mg_ws_wrap(c, c->send.len - len, WEBSOCKET_OP_BINARY);
} else {
MG_ERROR(("%lu MQTT auth failed, code %d", c->id, mm.ack));
c->is_draining = 1;
}
break;
case MQTT_CMD_PUBLISH: {
MG_DEBUG(("%lu [%.*s] -> [%.*s]", c->id, (int) mm.topic.len,
mm.topic.ptr, (int) mm.data.len, mm.data.ptr));
MG_INFO(("RECEIVED %.*s <- %.*s", (int) mm.data.len, mm.data.ptr,
(int) mm.topic.len, mm.topic.ptr));
c->is_draining = 1;
break;
}
}
wm->data.ptr += mm.dgram.len;
wm->data.len -= mm.dgram.len;
}
}
if (ev == MG_EV_ERROR || ev == MG_EV_CLOSE) {
*(bool *) fn_data = true; // Signal that we're done
}
}
int main(void) {
struct mg_mgr mgr; // Event manager
bool done = false; // Event handler flips it to true when done
mg_mgr_init(&mgr); // Initialise event manager
mg_log_set(MG_LL_DEBUG); // Set log level
mg_ws_connect(&mgr, s_url, fn, &done, NULL); // Create client connection
while (done == false) mg_mgr_poll(&mgr, 1000); // Event loop
mg_mgr_free(&mgr); // Finished, cleanup
return 0;
}