[Network] Broadcast 예제

[Broadcast Send]

#include <stdio.h>
#include <winsock2.h>
#include <windows.h>
 
int main(){
    WSADATA wsdata;
    WSAStartup(MAKEWORD(2,2), &wsdata);
    SOCKET sock = socket(AF_INET, SOCK_DGRAM, 0);
    int bcastOpt = 1;
    char buf[30];
    ZeroMemory(buf, sizeof(buf));
    strcpy(buf, "브로드캐스트 테스트~\n");
    SOCKADDR_IN addr;
    ZeroMemory(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr("255.255.255.255");
    addr.sin_port = htons(9999);
    setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (char*)&bcastOpt, sizeof(bcastOpt));
    int i;
    for(i=0; i<20; i++){
        sendto(sock, buf, sizeof(buf), 0, (SOCKADDR*)&addr, sizeof(addr));
        printf("sending...\n");
        Sleep(500);
    }
    closesocket(sock);
    return 0;
}

[Broadcast Recv]

#include <stdio.h>
#include <winsock2.h>
#include <windows.h>
 
int main(){
    WSADATA wsdata;
    WSAStartup(MAKEWORD(2,2), &wsdata);
    SOCKET sock = socket(AF_INET, SOCK_DGRAM, 0);
    SOCKADDR_IN addr;
    int bcastOpt = 1;
    setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (char*)&bcastOpt, sizeof(bcastOpt));
    ZeroMemory(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    //addr.sin_addr.s_addr = inet_addr("255.255.255.255");
    addr.sin_port = htons(9999);
    bind(sock, (SOCKADDR*)&addr, sizeof(addr));
    char buf[30];
    ZeroMemory(buf, sizeof(buf));
    while(1){
        recvfrom(sock, buf, sizeof(buf), 0, NULL, 0);
        fputs(buf, stdout);
    }
    closesocket(sock);
    return 0;
}