net_tcp_nonblocking.c

Non-blocking TCP server with polling.

Non-blocking TCP server with polling.Demonstrates: accept with zero timeout, bj_tcp_available(), polling pattern. Connect with tcp_client.c (change port to 8090) to test.

 
#include <banjo/log.h>
#include <banjo/main.h>
#include <banjo/net.h>
#include <banjo/system.h>
#include <banjo/time.h>
 
#include <stdio.h>
 
#define PORT 8090
#define MAX_CLIENTS 4
 
int main(int argc, char* argv[]) {
    (void)argc;
    (void)argv;
 
    if (!bj_begin(BJ_NETWORK_SYSTEM, 0)) {
        return 1;
    }
 
    struct bj_error* error = 0;
 
    struct bj_tcp_listener* listener = bj_listen_tcp("0.0.0.0", PORT, BJ_RESOLVE_IPV4, 5, &error);
    if (!listener) {
        bj_err("server: failed to listen (%s)", bj_error_message(error));
        bj_clear_error(&error);
        bj_end();
        return 1;
    }
 
    bj_info("server: listening on port %d (non-blocking mode)", bj_tcp_listener_port(listener));
    bj_info("server: polling for connections...");
 
    struct bj_tcp_stream* clients[MAX_CLIENTS] = {0};
    int client_count = 0;
 
    while (1) {
        // Try to accept new connections (non-blocking with 0 timeout)
        if (client_count < MAX_CLIENTS) {
            struct bj_tcp_stream* new_client = bj_accept_tcp(listener, 0, &error);
            if (new_client) {
                for (int i = 0; i < MAX_CLIENTS; i++) {
                    if (!clients[i]) {
                        clients[i] = new_client;
                        client_count++;
 
                        char addr[BJ_ADDR_STRLEN];
                        bj_tcp_peer_address(new_client, addr, sizeof(addr));
                        bj_info("server: client %d connected from %s", i, addr);
                        break;
                    }
                }
            } else if (error && bj_error_code(error) != BJ_ERROR_NETWORK_TIMEOUT) {
                bj_err("server: accept error (%s)", bj_error_message(error));
            }
            bj_clear_error(&error);
        }
 
        // Poll each connected client for data
        for (int i = 0; i < MAX_CLIENTS; i++) {
            if (!clients[i]) {
                continue;
            }
 
            int available = bj_tcp_available(clients[i]);
 
            if (available < 0) {
                bj_info("server: client %d disconnected", i);
                bj_close_tcp_stream(clients[i]);
                clients[i] = 0;
                client_count--;
                continue;
            }
 
            if (available > 0) {
                char buf[256];
                int n = bj_tcp_recv(clients[i], buf, sizeof(buf) - 1);
                if (n > 0) {
                    buf[n] = '\0';
                    bj_info("server: client %d sent: \"%s\"", i, buf);
 
                    char response[512];
                    int len = snprintf(response, sizeof(response), "[echo] %s", buf);
                    bj_tcp_send(clients[i], response, len);
                }
            }
        }
 
        bj_sleep(10);
    }
 
    for (int i = 0; i < MAX_CLIENTS; i++) {
        if (clients[i]) {
            bj_close_tcp_stream(clients[i]);
        }
    }
    bj_close_tcp_listener(listener);
    bj_end();
    return 0;
}