/*
 * Socket setup
 */
static int openSocket(const std::string& iface_name)
{
    const int s = ::socket(PF_CAN, SOCK_RAW, CAN_RAW);
    if (s < 0)
    {
        return s;
    }
    /*
     * Detect the iface index
     */
    auto ifr = ::ifreq();
    std::strncpy(ifr.ifr_name, iface_name.c_str(), IFNAMSIZ);
    if (::ioctl(s, SIOCGIFINDEX, &ifr) < 0)
    {
        return -1;
    }
    if (ifr.ifr_ifindex < 0)
    {
        return -1;
    }
    /*
     * Bind to a CAN iface
     */
    auto addr = ::sockaddr_can();
    addr.can_family = AF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;
    if (::bind(s, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) < 0)
    {
        return -1;
    }
    /*
     * Configure
     */
    const int on = 1;
    // Timestamping
    if (::setsockopt(s, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on)) < 0)
    {
        return -1;
    }
    // Socket loopback
    if (::setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS, &on, sizeof(on)) < 0)
    {
        return -1;
    }
    // Non-blocking
    if (::fcntl(s, F_SETFL , O_NONBLOCK) < 0)
    {
        return -1;
    }
    return s;
}

/*
 * Here's the problem
 */
int read(uavcan::CanFrame& frame, uavcan::UtcTime& ts_utc, bool& loopback) const
{
    auto iov = ::iovec();
    auto sockcan_frame = ::can_frame();
    iov.iov_base = &sockcan_frame;
    iov.iov_len = sizeof(sockcan_frame);
    auto msg = ::msghdr();
    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;

    const int res = ::recvmsg(fd_, &msg, MSG_DONTWAIT);
    if (res <= 0)
    {
        return res;
    }
    // At this point sockcan_frame contains valid data, i.e. generally recvmsg() works OK

    for (::cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg != nullptr; cmsg = CMSG_NXTHDR(&msg, cmsg))
    {
        // Problem: no control messages were received (msg.msg_controllen is zero)
        if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SO_TIMESTAMP)
        {
            <...>
        }
    }
    <...>
}