OpenBSD可加载内核模块编程完全指南

OpenBSD可加载内核模块编程完全指南(18)         }

        return(0);
}

/*
* 我们的外部接口,没有做什么,用到了DISPATCH宏
*/

int
tcpinfo(lkmtp, cmd, ver)
        struct lkm_table *lkmtp;
        int cmd;
        int ver;
{
        DISPATCH(lkmtp, cmd, ver, tcpmod_handler, tcpmod_handler, lkm_nofunc)
}

/*
* 定义我们自己的包装的tcp_input函数.假如mbuf里有包头,则打印出网络接口接收到的包
* 的总长度以及包的源地址.然后使原来的tcp_input函数正常运行.
*/

static void
new_input(struct mbuf *m, ...)
{
        va_list ap;
        int iphlen;
        struct ifnet *ifnp;
        struct ip *ip;

        va_start(ap, m);
        iphlen = va_arg(ap, int);
        va_end(ap);
        
        if (m->m_flags & M_PKTHDR) {
                ifnp = m->m_pkthdr.rcvif;
                ip = mtod(m, struct ip *);
                printf("incoming packet: %d bytes ", m->m_pkthdr.len);
                printf("on %s from %sn", ifnp->if_xname, inet_ntoa(ip->ip_src));