usr/src/sys/net/if_loop.c

/*      if_loop.c       4.7     82/03/19        */

/*
 * Loopback interface driver for protocol testing and timing.
 */

#include "../h/param.h"
#include "../h/systm.h"
#include "../h/mbuf.h"
#include "../h/socket.h"
#include "../net/in.h"
#include "../net/in_systm.h"
#include "../net/if.h"
#include "../net/ip.h"
#include "../net/ip_var.h"
#include "../h/mtpr.h"

#define LONET   127
#define LOMTU   (1024+512)

struct  ifnet loif;
int     looutput();

loattach()
{
        register struct ifnet *ifp = &loif;

        ifp->if_name = "lo";
        ifp->if_mtu = LOMTU;
        ifp->if_net = LONET;
        ifp->if_addr = if_makeaddr(ifp->if_net, 0);
        ifp->if_output = looutput;
        if_attach(ifp);
}

looutput(ifp, m0, pf)
        struct ifnet *ifp;
        struct mbuf *m0;
        int pf;
{
        int s = splimp();
        register struct ifqueue *ifq;

        ifp->if_opackets++;
        switch (pf) {

#ifdef INET
        case PF_INET:
                ifq = &ipintrq;
                if (IF_QFULL(ifq)) {
                        IF_DROP(ifq);
                        (void) m_freem(m0);
                        splx(s);
                        return (0);
                }
                IF_ENQUEUE(ifq, m0);
                schednetisr(NETISR_IP);
                break;
#endif

        default:
                splx(s);
                printf("lo%d: can't encapsulate pf%d\n", ifp->if_unit, pf);
                (void) m_freem(m0);
                return (0);
        }
        ifp->if_ipackets++;
        splx(s);
        return (1);
}