Protocol Registration

For the mynewproto() callback, the caller fills in only the proto argument. Neither an event nor a hook name can be provided at this point. The following example looks for only the events that announce the registration of the IPv4 protocol.

The next step in this function is to discover when events are added to the IPv4 protocol by using the net_protocol_notify_register() interface to register the mynewevent() function.

static int
mynewproto(hook_notify_cmd_t cmd, void *arg, const char *proto,
    const char *event, const char *hook)
{
    mytype_t *ctx = arg;

    if (strcmp(proto, NHF_INET) != 0)
        return (0);

    switch (cmd) {
        case HN_REGISTER :
            ctx->inet = net_protocol_lookup(s->id, proto);
            net_protocol_notify_register(s->inet, mynewevent, ctx);
            break;
        case HN_UNREGISTER :
        case HN_NONE :
            break;
    }
    return (0);
}

The following table lists all three protocols that could be expected to be seen with the mynewproto() callback. New protocols could be added in the future, so you must safely fail (return the value 0) any unknown protocols.

Programming Symbol	Protocol
NHF_INET	IPv4
NHF_INET6	IPv6
NHF_ARP	ARP