net_udp_broadcast_recv.c

UDP broadcast receiver for LAN discovery.

UDP broadcast receiver for LAN discovery.Demonstrates: receiving broadcast messages, bj_udp_wait with timeout. Pair with udp_broadcast_send.c to test.

 
#include <banjo/log.h>
#include <banjo/main.h>
#include <banjo/net.h>
#include <banjo/system.h>
 
#include <string.h>
 
#define PORT 9999
 
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_udp* udp = bj_open_udp("0.0.0.0", PORT, BJ_RESOLVE_IPV4, &error);
    if (!udp) {
        bj_err("discover: failed to open socket (%s)", bj_error_message(error));
        bj_clear_error(&error);
        bj_end();
        return 1;
    }
 
    bj_info("discover: listening for broadcasts on port %d", PORT);
 
    while (1) {
        if (!bj_udp_wait(udp, 5000)) {
            bj_info("discover: no broadcasts received in last 5 seconds...");
            continue;
        }
 
        struct bj_datagram* dgram = bj_udp_recv(udp, &error);
        if (!dgram) {
            if (error) {
                bj_err("discover: recv error (%s)", bj_error_message(error));
                bj_clear_error(&error);
            }
            continue;
        }
 
        char addr[BJ_ADDR_STRLEN];
        bj_datagram_addr(dgram, addr, sizeof(addr));
 
        char message[256];
        size_t len = bj_datagram_len(dgram);
        if (len >= sizeof(message)) {
            len = sizeof(message) - 1;
        }
        memcpy(message, bj_datagram_data(dgram), len);
        message[len] = '\0';
 
        bj_info("discover: found service at %s:%d - \"%s\"",
                addr, bj_datagram_port(dgram), message);
 
        bj_close_datagram(dgram);
    }
 
    bj_close_udp(udp);
    bj_end();
    return 0;
}