Function protect_socket_binddev

src/netcfg/core-tunbuilder.cpp:348–382

void protect_socket_binddev(int fd, const std::string &remote, bool ipv6)
{
    std::string bestdev;

    if (ipv6)
    {
        IPv6::Addr bestgw;
        IP::Route6 hostroute(IPv6::Addr::from_string(remote), 128);
        if (openvpn::TunNetlink::SITNL::net_route_best_gw(hostroute, bestgw, bestdev) != 0)
        {
            throw NetCfgException("Failed retrieving IPv6 gateway for "
                                  + remote + " failed");
        }
    }
    else
    {
        IPv4::Addr bestgw;
        IP::Route4 hostroute(IPv4::Addr::from_string(remote), 32);
        if (TunNetlink::SITNL::net_route_best_gw(hostroute, bestgw, bestdev) != 0)
        {
            throw NetCfgException("Failed retrieving IPv4 gateway for "
                                  + remote + " failed");
        }
    }

    OPENVPN_LOG("Protecting socket " + std::to_string(fd)
                + " to '" + remote + "'(" + (ipv6 ? "inet6" : "inet")
                + ") by binding it to '" + bestdev + "'");

    if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, (void *)bestdev.c_str(), strlen(bestdev.c_str())) < 0)
    {
        throw NetCfgException("Failed binding (SO_BINDTODEVICE) to "
                              + bestdev + " failed: " + strerror(errno));
    }
}