Error "No such device" in call setsockopt

Question

Hello, everyone! I need help! I have a code in which send multicast datagrams. A critical piece of code:

        uint32_t port;
        int sockfd, err_ip;
        const uint32_t sizebuff = 65535 - (20 + 8);
        unsigned char *buff = (unsigned char *) malloc(sizebuff);
        struct sockaddr_in servaddr, cliaddr;
        struct in_addr serv_in_addr;
        struct ip_mreq req;

        port = str2uint16(cmdsrv->ipport);
        bzero(buff, (size_t)sizebuff);
        bzero(&servaddr, sizeof(servaddr));
        bzero(&serv_in_addr, sizeof(serv_in_addr));
        err_ip = inet_aton(cmdsrv->ipaddr, &serv_in_addr);

        if ((err_ip != 0) && (port != 0))
        {
            servaddr.sin_family = AF_INET;
            servaddr.sin_addr = serv_in_addr;
            servaddr.sin_port = htons(port);
            memcpy(&req.imr_multiaddr,&serv_in_addr,sizeof(req.imr_multiaddr));
            req.imr_interface.s_addr = INADDR_ANY;
            sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

            if (sockfd == -1) 
            {
                int outerror = errno;
                char *retstr = "Couldn't open socket\n";
                pthread_exit(retstr);
            }
            else 
            {
                struct in_addr ifaddr;
                ifaddr.s_addr = INADDR_ANY;
                int optres3 = setsockopt(sockfd,IPPROTO_IP,IP_MULTICAST_IF,&ifaddr,sizeof(ifaddr));
                if (optres3 == -1)
                {
                    int perrno = errno;
                    char *retstr = "Can't set IP_MULTICAST_IF for socket\n";
                    printf("Error setsockopt: ERRNO = %s\n",strerror(perrno));
                    printf("%s",retstr);
                    pthread_exit(retstr);
                }

                unsigned char ttl = 32;
                int optres2 = setsockopt(sockfd,IPPROTO_IP,IP_MULTICAST_TTL,&ttl,sizeof(ttl));
                if (optres2 == -1)
                {
                    int perrno = errno;
                    char *retstr = "Can't set IP_MULTICAST_TTL for socket\n";
                    printf("Error setsockopt: ERRNO = %s\n",strerror(perrno));
                    printf("%s",retstr);
                    pthread_exit(retstr);
                }
                int optres = setsockopt(sockfd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&req,sizeof(req));
                if (optres == -1)
                {
                    int perrno = errno;
                    char *retstr = "Can't join to multicast-group\n";
                    printf("Error setsockopt: ERRNO = %s\n",strerror(perrno));
                    printf("%s",retstr);
                    pthread_exit(retstr);
                }
                // Bind port with socket
                uint16_t cliport;
                cliaddr.sin_family = AF_INET;
                cliaddr.sin_addr.s_addr = INADDR_ANY;

                if (strcmp(cmdsrv->ipport,"16011") == 0)
                {
                    cliport = str2uint16("16003");
                    cliaddr.sin_port = htons(cliport);
                }
                else if (strcmp(cmdsrv->ipport,"16012") == 0)
                {
                    cliport = str2uint16("16004");
                    cliaddr.sin_port = htons(cliport);                      
                }
                else 
                {
                    printf("Device hasn't such port");
                    pthread_exit(NULL);
                }

                int bindres = bind(sockfd,(struct sockaddr*)&cliaddr,sizeof(cliaddr));
                if (bindres == -1)
                {
                    int perrno = errno;
                    perror("Error in bind\n");
                }
                //ADD 1 BYTE
                data rawdata;
                rawdata.desc = 23;
                printf("SIZEOF = %d\n",sizeof(*(cmdsrv->cmd)));
                memcpy(&rawdata.cmd, cmdsrv->cmd, sizeof(*(cmdsrv->cmd)));
                printf("RAWDATA: desc = %d, cmd = %d\n",rawdata.desc,rawdata.cmd);

                int outerror = 0;
                printf("Send command to IP:\n addr = %s, port = %d\n",inet_ntoa(servaddr.sin_addr),ntohs(servaddr.sin_port));
                int size = sendto(sockfd, &rawdata, sizeof(rawdata), 0, (struct sockaddr*) &servaddr, sizeof(servaddr));
                if (size == -1)
                {
                    perror("Can't send command to socket");
                }
      ...

Sometimes program executes succefully (at this moment I have IP - 192.168.80.122). I can capture my multicast datagram by wireshark. That's all OK.

But if I change my IP to 192.168.1.2 I get error when is called

int optres = setsockopt(sockfd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&req,sizeof(req));

And I can't even capture my multicast packet. Nothing is sent. Where's bug? Please, help me.

Answer 1

If it works for one IP but not for another, maybe this can help.

Answer 2

IP_ADD_MEMBERSHIP and bind() are only required for receiving multicast, use IP_MULTICAST_IF instead for send-only membership of a multicast group.

Answer 3

Is this a typo in the original question, or from the code?

But if I change my IP to 192.168.1.2.1 I get error when is called

It looks like an extra .1 on the end here.