T_X

/**
 * CC0 - Linus Lüssing
 */

#include <stdio.h>      // for fprintf()
#include <net/if.h>     // for if_nametoindex()
#include <stdlib.h>     // for atoi() and exit()
#include <arpa/inet.h>  // for sockaddr_in and inet_addr()
#include <string.h>     // for memset()

int create_client_multirecv_socket(char *multicastIP, unsigned int multicastPort, char *interface)
{
    int sd;                 // Socket descriptor
    struct sockaddr_in6 multicastAddr;  // Multicast addresse structure
    struct ipv6_mreq multicastRequest;  // Multicast address join structure

    // Construct bind structure
    memset(&multicastAddr, 0, sizeof(multicastAddr));   // Zero out structure
    multicastAddr.sin6_family = AF_INET6;       // Internet address family
    multicastAddr.sin6_addr = in6addr_any;      // Any incoming interface
    multicastAddr.sin6_port = htons(multicastPort); // Multicast port

    // Create a best-effort datagram socket using UDP
    if((sd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
        perror("socket() failed");
        return -1;
    }
    // Bind to the multicast port
    if(bind(sd, (struct sockaddr *) &multicastAddr, sizeof(multicastAddr)) < 0) {
        perror("bind() failed");
        return -1;
    }
    // Specify the multicast group
    if(!inet_pton(AF_INET6, multicastIP, &multicastRequest.ipv6mr_multiaddr)) {
        fprintf(stderr, "Invalid IP-address: %s", multicastIP);
        return -1;
    }
    // Accept multicast from specified interface
    multicastRequest.ipv6mr_interface = if_nametoindex(interface);

    // Join the multicast address
    if(setsockopt(sd, IPPROTO_IPV6, IPV6_JOIN_GROUP, (void *) &multicastRequest,
        sizeof(multicastRequest)) < 0) {
        perror("setsockopt() failed");
        return -1;
    }

    return sd;
}



int main(int argc, char *argv[])
{
    int sd;

    if (argc < 3) {
        perror("Not enough command line arguments (must be 2, multicast group and interface");
        exit(1);
    }

    sd = create_client_multirecv_socket(argv[2], 12999, argv[1]);
    if(sd < 0) {
        perror("create_client_multirecv_socket failed");
        exit(1);
    }

    while(1)
        sleep(100);

    close(sd);

    return 0;
}