Mongoose is a network library for C/C++. It provides event-driven non-blocking APIs for TCP, UDP, HTTP, WebSocket, MQTT, and other protocols. It is designed for connecting devices and bringing them online. On the market since 2004, used by vast number of open source and commercial products - it even runs on the International Space Station! Mongoose makes embedded network programming fast, robust, and easy. Features include:
See https://mongoose.ws/ for complete documentation, videos, case studies, etc.
Below are quick snippets that should give an idea how simple the API is and how easy it is to create applications with it.
Create a simple web server that serves a directory. The behavior of the HTTP server is specified by its event handler function:
#include "mongoose.h" // To build, run: cc main.c mongoose.c
// HTTP server event handler function
void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
struct mg_http_serve_opts opts = { .root_dir = "./web_root/" };
mg_http_serve_dir(c, hm, &opts);
}
}
int main(void) {
struct mg_mgr mgr; // Declare event manager
mg_mgr_init(&mgr); // Initialise event manager
mg_http_listen(&mgr, "http://0.0.0.0:8000", ev_handler, NULL); // Setup listener
for (;;) { // Run an infinite event loop
mg_mgr_poll(&mgr, 1000);
}
return 0;
}
HTTP server implements a REST API that returns current time. JSON formatting:
static void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
if (mg_match(hm->uri, mg_str("/api/time/get"), NULL)) {
mg_http_reply(c, 200, "", "{%m:%lu}\n", MG_ESC("time"), time(NULL));
} else {
mg_http_reply(c, 500, "", "{%m:%m}\n", MG_ESC("error"), MG_ESC("Unsupported URI"));
}
}
}
MQTT client that subscribes to a topic device1/rx
and
echoes incoming messages to device1/tx
:
#include "mongoose.h"
static const char *s_mqtt_url = "mqtt://broker.hivemq.com:1883";
static struct mg_connection *s_mqtt_conn = NULL;
// MQTT connection event handler function
static void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
if (ev == MG_EV_OPEN) {
MG_INFO(("%lu created, connecting to %s ...", c->id, s_mqtt_url));
} else if (ev == MG_EV_MQTT_OPEN) {
struct mg_mqtt_opts opts = {.qos = 1, .topic = mg_str("device1/rx")};
mg_mqtt_sub(c, &opts);
MG_INFO(("%lu connected, subscribing to %s", c->id, opts.topic.buf));
} else if (ev == MG_EV_MQTT_MSG) {
char response[100];
struct mg_mqtt_message *mm = (struct mg_mqtt_message *) ev_data;
struct mg_mqtt_opts opts = {.qos = 1, .topic = mg_str("device1/tx")};
mg_snprintf(response, sizeof(response), "Received [%.*s] / [%.*s]",
mm->topic.len, mm->topic.buf, mm->data.len, mm->data.buf);
opts.message = mg_str(response);
mg_mqtt_pub(c, &opts);
} else if (ev == MG_EV_CLOSE) {
MG_INFO(("%u closing", c->id));
s_mqtt_conn = NULL;
}
}
// Reconnection timer function. If we get disconnected, reconnect again
static void timer_fn(void *arg) {
struct mg_mgr *mgr = (struct mg_mgr *) arg;
if (s_mqtt_conn == NULL) {
struct mg_mqtt_opts opts = {.clean = true};
s_mqtt_conn = mg_mqtt_connect(mgr, s_mqtt_url, &opts, ev_handler, NULL);
}
}
int main() {
struct mg_mgr mgr; // Mongoose event manager. Holds all connections
mg_mgr_init(&mgr); // Initialise event manager
mg_timer_add(&mgr, 3000, MG_TIMER_REPEAT | MG_TIMER_RUN_NOW, timer_fn, &mgr);
for (;;) {
mg_mgr_poll(&mgr, 1000); // Infinite event loop
}
return 0;
}
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