mongoose/examples/tcp/main.c

// Copyright (c) 2022 Cesanta Software Limited
// All rights reserved

#include "mongoose.h"

static const char *s_lsn = "tcp://localhost:8765";   // Listening address
static const char *s_conn = "tcp://localhost:8765";  // Connect to address

// client resources
static struct c_res_s {
  int i;
  struct mg_connection *c;
} c_res;

// CLIENT event handler
static void cfn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
  int *i = &((struct c_res_s *) fn_data)->i;
  if (ev == MG_EV_OPEN) {
    MG_INFO(("CLIENT has been initialized"));
  } else if (ev == MG_EV_CONNECT) {
    MG_INFO(("CLIENT connected"));
    *i = 1;  // do something
  } else if (ev == MG_EV_READ) {
    struct mg_iobuf *r = &c->recv;
    MG_INFO(("CLIENT got data: %.*s", r->len, r->buf));
  } else if (ev == MG_EV_CLOSE) {
    MG_INFO(("CLIENT disconnected"));
    // signal we are done
    ((struct c_res_s *) fn_data)->c = NULL;
  } else if (ev == MG_EV_ERROR) {
    MG_INFO(("CLIENT error: %s", (char *) ev_data));
  } else if (ev == MG_EV_POLL && *i != 0) {
    switch ((*i)++) {
      case 50:  // 50 x 100ms = 5s
        mg_send(c, "Hi, there", 9);
        MG_INFO(("CLIENT sent data"));
        break;
      case 100:  // another 5s
        // send any possible outstanding data and close the connection
        c->is_draining = 1;
        break;
    }
  }
}

// SERVER event handler
static void sfn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
  if (ev == MG_EV_OPEN && c->is_listening == 1) {
    MG_INFO(("SERVER is listening"));
  } else if (ev == MG_EV_ACCEPT) {
    MG_INFO(("SERVER accepted a connection"));
  } else if (ev == MG_EV_READ) {
    struct mg_iobuf *r = &c->recv;
    MG_INFO(("SERVER got data: %.*s", r->len, r->buf));
    mg_send(c, r->buf, r->len);  // echo it back
  } else if (ev == MG_EV_CLOSE) {
    MG_INFO(("SERVER disconnected"));
  } else if (ev == MG_EV_ERROR) {
    MG_INFO(("SERVER error: %s", (char *) ev_data));
  }
  (void) fn_data;
}

// Timer function - recreate client connection if it is closed
static void timer_fn(void *arg) {
  struct mg_mgr *mgr = (struct mg_mgr *) arg;
  if (c_res.c == NULL) {
    // connect
    c_res.i = 0;
    c_res.c = mg_connect(mgr, s_conn, cfn, &c_res);
    if (c_res.c == NULL)
      MG_INFO(("CLIENT cant' open a connection"));
    else
      MG_INFO(("CLIENT is connecting"));
  }
}

int main(void) {
  struct mg_mgr mgr;  // Event manager
  struct mg_connection *c;

  mg_log_set("2");    // Set to 0 to disable debug
  mg_mgr_init(&mgr);  // Initialize event manager
  mg_timer_add(&mgr, 15000, MG_TIMER_REPEAT | MG_TIMER_RUN_NOW, timer_fn,
               &mgr);                     // Init timer for demo purposes, 15s
  c = mg_listen(&mgr, s_lsn, sfn, NULL);  // Create server connection
  if (c == NULL) {
    MG_INFO(("SERVER cant' open a connection"));
    return 0;
  }
  while (true)
    mg_mgr_poll(&mgr, 100);  // Infinite event loop, blocks for upto 100ms
                             // unless there is network activity
  mg_mgr_free(&mgr);         // Free resources
  return 0;
}