#include #include #include #include #include #ifdef _WIN32 #include #include #pragma comment(lib, "Ws2_32.lib") #else #include #include #include #include #endif #define MCAST_PORT 4532 #define MCAST_ADDR "224.0.0.1" #define BUFFER_SIZE 4096 int main() { int sock; struct sockaddr_in mcast_addr; char buffer[BUFFER_SIZE]; int bytes_received; #ifdef _WIN32 WSADATA wsaData; if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) { fprintf(stderr, "WSAStartup failed: %d\n", WSAGetLastError()); return 1; } #endif if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) { perror("socket() failed"); exit(EXIT_FAILURE); } // Set the SO_REUSEADDR option to allow multiple processes to use the same address int optval = 1; if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char *)&optval, sizeof(optval)) < 0) { //rig_debug(RIG_DEBUG_ERR, "%s: setsockopt: %s\n", __func__, strerror(errno)); //return -RIG_EIO; return 1; } memset(&mcast_addr, 0, sizeof(mcast_addr)); mcast_addr.sin_family = AF_INET; mcast_addr.sin_port = htons(MCAST_PORT); mcast_addr.sin_addr.s_addr = htonl(INADDR_ANY); if (bind(sock, (struct sockaddr *)&mcast_addr, sizeof(mcast_addr)) < 0) { perror("bind() failed"); exit(EXIT_FAILURE); } struct ip_mreq mreq; mreq.imr_multiaddr.s_addr = inet_addr(MCAST_ADDR); mreq.imr_interface.s_addr = htonl(INADDR_ANY); if (setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&mreq, sizeof(mreq)) < 0) { perror("setsockopt() failed"); exit(EXIT_FAILURE); } while (1) { bytes_received = recvfrom(sock, buffer, BUFFER_SIZE, 0, NULL, 0); if (bytes_received < 0) { perror("recvfrom() failed"); break; } buffer[bytes_received] = '\0'; printf("Received: %s\n", buffer); } // Drop membership before closing the socket if (setsockopt(sock, IPPROTO_IP, IP_DROP_MEMBERSHIP, (char *)&mreq, sizeof(mreq)) < 0) { perror("setsockopt() failed"); } close(sock); #ifdef _WIN32 WSACleanup(); #endif return 0; }