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107 lines
4.1 KiB
C
107 lines
4.1 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_topic`
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// 3. Publishes message `hello` to the `s_topic`
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// 4. Receives that message back from the subscribed topic and exits
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//
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// To enable SSL/TLS, see https://mongoose.ws/tutorials/tls/#how-to-build
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#include "mongoose.h"
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static const char *s_url =
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#if MG_TLS
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"wss://broker.hivemq.com:8884/mqtt";
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#else
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"ws://broker.hivemq.com:8000/mqtt";
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#endif
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static const char *s_topic = "mg/test";
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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_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_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_WS_OPEN) {
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// WS connection established. Perform MQTT login
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MG_INFO(("Connected to WS. Logging in to MQTT..."));
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struct mg_mqtt_opts opts = {
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.qos = 1, .topic = mg_str(s_topic), .message = mg_str("goodbye")};
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size_t len = c->send.len;
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mg_mqtt_login(c, &opts);
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mg_ws_wrap(c, c->send.len - len, WEBSOCKET_OP_BINARY);
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c->is_hexdumping = 1;
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} else if (ev == MG_EV_WS_MSG) {
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struct mg_mqtt_message mm;
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struct mg_ws_message *wm = (struct mg_ws_message *) ev_data;
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uint8_t version = c->is_mqtt5 ? 5 : 4;
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MG_INFO(("GOT %d bytes WS msg", (int) wm->data.len));
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while ((mg_mqtt_parse((uint8_t *) wm->data.ptr, wm->data.len, version,
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&mm)) == MQTT_OK) {
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switch (mm.cmd) {
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case MQTT_CMD_CONNACK:
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mg_call(c, MG_EV_MQTT_OPEN, &mm.ack);
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if (mm.ack == 0) {
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struct mg_str topic = mg_str(s_topic), data = mg_str("hello");
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size_t len = c->send.len;
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MG_INFO(("CONNECTED to %s", s_url));
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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 = 1;
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mg_mqtt_sub(c, &sub_opts);
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len = mg_ws_wrap(c, c->send.len - len, WEBSOCKET_OP_BINARY);
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MG_INFO(("SUBSCRIBED to %.*s", (int) topic.len, topic.ptr));
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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 = 1, pub_opts.retain = false;
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mg_mqtt_pub(c, &pub_opts);
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MG_INFO(("PUBLISHED %.*s -> %.*s", (int) data.len, data.ptr,
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(int) topic.len, topic.ptr));
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len = mg_ws_wrap(c, c->send.len - len, WEBSOCKET_OP_BINARY);
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} else {
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MG_ERROR(("%lu MQTT auth failed, code %d", c->id, mm.ack));
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c->is_draining = 1;
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}
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break;
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case MQTT_CMD_PUBLISH: {
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MG_DEBUG(("%lu [%.*s] -> [%.*s]", c->id, (int) mm.topic.len,
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mm.topic.ptr, (int) mm.data.len, mm.data.ptr));
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MG_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_draining = 1;
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break;
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}
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}
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wm->data.ptr += mm.dgram.len;
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wm->data.len -= mm.dgram.len;
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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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*(bool *) 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; // Event manager
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bool done = false; // Event handler flips it to true when done
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mg_mgr_init(&mgr); // Initialise event manager
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mg_log_set(MG_LL_DEBUG); // Set log level
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mg_ws_connect(&mgr, s_url, fn, &done, "%s", // Create client connection
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"Sec-Websocket-Protocol: mqtt\r\n"); // Request MQTT protocol
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while (done == false) mg_mgr_poll(&mgr, 1000); // Event loop
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mg_mgr_free(&mgr); // Finished, cleanup
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return 0;
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}
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