linux 发广播包

int broadcastsendmsg(int fd, int port, const char* buf)
{
    struct sockaddr_in remote;
    ssize_t ret;
    struct ifaddrs * ifAddr = NULL;
    struct  sockaddr_in* saddr = NULL;


    remote.sin_family = AF_INET;
    remote.sin_addr.s_addr = htonl(INADDR_BROADCAST);
    remote.sin_port = htons(port);
    memset(&(remote.sin_zero), 0, 8);


    getifaddrs(&ifAddr);
    while (ifAddr != NULL)
    {
        /* ignore lo and ipv6 */
        if(strcmp(ifAddr->ifa_name, "lo") && ifAddr->ifa_addr->sa_family == AF_INET)
        {
            unsigned int addr = 0;
            unsigned int mask = 0;


            saddr = (struct sockaddr_in *)ifAddr->ifa_addr;
            addr = saddr->sin_addr.s_addr;
            saddr = (struct sockaddr_in *)ifAddr->ifa_netmask;
            mask = saddr->sin_addr.s_addr;


            if(0)
            {
                struct in_addr sin_addr;
                sin_addr.s_addr = addr & mask;
                char addressBuffer[INET_ADDRSTRLEN];
                inet_ntop(AF_INET, (void*)&sin_addr, addressBuffer, INET_ADDRSTRLEN);


                printf("net addr :%s\n", addressBuffer);
            }


            remote.sin_addr.s_addr = addr & mask;
            ret = sendto(fd, buf, strlen(buf) , 0, (struct sockaddr*)&remote, sizeof(remote));
            if(ret == -1)
            {
                perr("sendto");
                loge("broadcastsendmsg fail\n");
                return -1;
            }


            if((size_t )ret != strlen(buf))
            {
                loge("sendto send data not complete, err\n");
                return -2;
            }
        }


        ifAddr = ifAddr->ifa_next;
    }


    return 1;
}