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[unix-history] / usr / src / sbin / routed / routed.c

#ifndef lint
static char sccsid[] = "@(#)routed.c    4.15 82/06/09";
#endif

/*
* Routing Table Management Daemon
*/
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/in.h>
#include <net/if.h>
#include <errno.h>
#include <stdio.h>
#include <nlist.h>
#include <signal.h>
#include <time.h>
#define RIPCMDS
#include "rip.h"
#include "router.h"

#define LOOPBACKNET     0177
/* casts to keep lint happy */
#define insque(q,p)     _insque((caddr_t)q,(caddr_t)p)
#define remque(q)       _remque((caddr_t)q)
#define equal(a1, a2) \
       (bcmp((caddr_t)(a1), (caddr_t)(a2), sizeof (struct sockaddr)) == 0)
#define min(a,b)        ((a)>(b)?(b):(a))

struct nlist nl[] = {
#define N_IFNET         0
       { "_ifnet" },
       0,
};

struct  sockaddr_in routingaddr = { AF_INET, IPPORT_ROUTESERVER };
struct  sockaddr_in noroutingaddr = { AF_INET, IPPORT_ROUTESERVER+1 };

int     s;
int     snoroute;               /* socket with no routing */
int     kmem = -1;
int     supplier = -1;          /* process should supply updates */
int     install = 1;            /* if 1 call kernel */
int     timeval = -TIMER_RATE;
int     timer();
int     cleanup();

#define tprintf if (trace) printf
int     trace = 0;
FILE    *ftrace;

char    packet[MAXPACKETSIZE+1];
struct  rip *msg = (struct rip *)packet;

struct in_addr if_makeaddr();
struct ifnet *if_ifwithaddr(), *if_ifwithnet();
extern char *malloc();
extern int errno, exit();
char    **argv0;

int     sendmsg(), supply();

main(argc, argv)
       int argc;
       char *argv[];
{
       int cc;
       struct sockaddr from;
       
       argv0 = argv;
#ifndef DEBUG
       if (fork())
               exit(0);
       for (cc = 0; cc < 10; cc++)
               (void) close(cc);
       (void) open("/", 0);
       (void) dup2(0, 1);
       (void) dup2(0, 2);
       { int t = open("/dev/tty", 2);
         if (t >= 0) {
               ioctl(t, TIOCNOTTY, (char *)0);
               (void) close(t);
         }
       }
#endif
       if (trace) {
               ftrace = fopen("/etc/routerlog", "w");
               dup2(fileno(ftrace), 1);
               dup2(fileno(ftrace), 2);
       }
#ifdef vax || pdp11
       routingaddr.sin_port = htons(routingaddr.sin_port);
       noroutingaddr.sin_port = htons(noroutingaddr.sin_port);
#endif
again:
       s = socket(SOCK_DGRAM, 0, &routingaddr, 0);
       if (s < 0) {
               perror("socket");
               sleep(30);
               goto again;
       }
again2:
       snoroute = socket(SOCK_DGRAM, 0, &noroutingaddr, SO_DONTROUTE);
       if (snoroute < 0) {
               perror("socket");
               sleep(30);
               goto again2;
       }
       argv++, argc--;
       while (argc > 0 && **argv == '-') {
               if (!strcmp(*argv, "-s") == 0) {
                       supplier = 1;
                       argv++, argc--;
                       continue;
               }
               if (!strcmp(*argv, "-q") == 0) {
                       supplier = 0;
                       argv++, argc--;
                       continue;
               }
               goto usage;
       }
       if (argc > 0) {
usage:
               fprintf(stderr, "usage: routed [ -s ]\n");
               exit(1);
       }
       rtinit();
       ifinit();
       if (supplier < 0)
               supplier = 0;
       gwkludge();
       msg->rip_cmd = RIPCMD_REQUEST;
       msg->rip_nets[0].rip_dst.sa_family = AF_UNSPEC;
       msg->rip_nets[0].rip_metric = HOPCNT_INFINITY;
       toall(sendmsg);
       sigset(SIGALRM, timer);
       timer();

       for (;;) {
               cc = receive(s, &from, packet, sizeof (packet));
               if (cc <= 0) {
                       if (cc < 0 && errno != EINTR)
                               perror("receive");
                       continue;
               }
               sighold(SIGALRM);
               rip_input(&from, cc);
               sigrelse(SIGALRM);
       }
}

rtinit()
{
       register struct rthash *rh;

       for (rh = nethash; rh < &nethash[ROUTEHASHSIZ]; rh++)
               rh->rt_forw = rh->rt_back = (struct rt_entry *)rh;
       for (rh = hosthash; rh < &hosthash[ROUTEHASHSIZ]; rh++)
               rh->rt_forw = rh->rt_back = (struct rt_entry *)rh;
}

struct  ifnet *ifnet;

ifinit()
{
       struct ifnet *ifp, *next;
       int uniquemultihostinterfaces = 0;

       nlist("/vmunix", nl);
       if (nl[N_IFNET].n_value == 0) {
               printf("ifnet: not in namelist\n");
               goto bad;
       }
       kmem = open("/dev/kmem", 0);
       if (kmem < 0) {
               perror("/dev/kmem");
               goto bad;
       }
       if (lseek(kmem, (long)nl[N_IFNET].n_value, 0) == -1 ||
           read(kmem, (char *)&next, sizeof (next)) != sizeof (next)) {
               printf("ifnet: error reading kmem\n");
               goto bad;
       }
       while (next) {
               ifp = (struct ifnet *)malloc(sizeof (struct ifnet));
               if (ifp == 0) {
                       printf("routed: out of memory\n");
                       break;
               }
               if (lseek(kmem, (long)next, 0) == -1 ||
                   read(kmem, (char *)ifp, sizeof (*ifp)) != sizeof (*ifp)) {
                       perror("read");
                       goto bad;
               }
               next = ifp->if_next;
               if (ifp->if_addr.sa_family != AF_INET)
                       continue;
               if (ifp->if_net == LOOPBACKNET)
                       continue;
               if ((ifp->if_flags & IFF_POINTOPOINT) == 0 ||
                   if_ifwithaddr(&ifp->if_dstaddr) == 0)
                       uniquemultihostinterfaces++;
               ifp->if_next = ifnet;
               ifnet = ifp;
               addrouteforif(ifp);
       }
       if (uniquemultihostinterfaces > 1 && supplier < 0)
               supplier = 1;
       return;
bad:
       sleep(60);
       execv("/etc/routed", argv0);
       _exit(0177);
}

addrouteforif(ifp)
       struct ifnet *ifp;
{
       struct sockaddr_in net;
       struct sockaddr *dst;

       if (ifp->if_flags & IFF_POINTOPOINT)
               dst = &ifp->if_dstaddr;
       else {
               bzero((char *)&net, sizeof (net));
               net.sin_family = AF_INET;
               net.sin_addr = if_makeaddr(ifp->if_net, INADDR_ANY);
               dst = (struct sockaddr *)&net;
       }
       rtadd(dst, &ifp->if_addr, 0, RTS_DONTDELETE|RTS_DONTROUTE);
}

gwkludge()
{
       struct sockaddr_in dst, gate;
       FILE *fp;
       char buf[BUFSIZ];

       fp = fopen("/etc/gateways", "r");
       if (fp == NULL)
               return;
       bzero((char *)&dst, sizeof (dst));
       bzero((char *)&gate, sizeof (gate));
       dst.sin_family = AF_INET;
       gate.sin_family = AF_INET;
       for (;;) {
               buf[0] = '\0';
               /* format is: dst XX gateway XX [passive]\n */
               if (fscanf(fp, "dst %x gateway %x %s\n", &dst.sin_addr.s_addr, 
                  &gate.sin_addr.s_addr, buf) == EOF)
                       break;
               rtadd((struct sockaddr *)&dst, (struct sockaddr *)&gate, 1,
                  strcmp(buf, "passive") == 0 ? RTS_PASSIVE : RTS_DONTDELETE);
       }
       fclose(fp);
}

timer()
{
       register struct rthash *rh;
       register struct rt_entry *rt;
       struct rthash *base = hosthash;
       int doinghost = 1, state;

       timeval += TIMER_RATE;
       tprintf(">>> time %d >>>\n", timeval);
again:
       for (rh = base; rh < &base[ROUTEHASHSIZ]; rh++) {
               rt = rh->rt_forw;
               for (; rt != (struct rt_entry *)rh; rt = rt->rt_forw) {
                       if (!(rt->rt_state & RTS_PASSIVE)) {
                               rt->rt_timer += TIMER_RATE;
                               if (rt->rt_timer > 9999)
                                       rt->rt_timer = 9999;
                       }
                       log("", rt);
                       if (rt->rt_state & RTS_HIDDEN)
                               continue;
                       if (rt->rt_timer >= EXPIRE_TIME)
                               rt->rt_metric = HOPCNT_INFINITY;
                       if ((rt->rt_state & RTS_DELRT) ||
                           rt->rt_timer >= GARBAGE_TIME) {
                               rt = rt->rt_back;
                               rtdelete(rt->rt_forw);
                               continue;
                       }
                       state = rt->rt_state;
                       if (rt->rt_state & RTS_ADDRT) {
                               if (ioctl(s, SIOCADDRT,(char *)&rt->rt_rt) < 0)
                                       perror("SIOCADDRT");
                               rt->rt_state &= ~RTS_ADDRT;
                       }
                       if (rt->rt_state & RTS_CHGRT) {
                               struct rtentry oldroute;

                               oldroute = rt->rt_rt;
                               oldroute.rt_gateway = rt->rt_oldrouter;
                               if (install &&
                                   ioctl(s, SIOCADDRT,(char *)&rt->rt_rt) < 0)
                                       perror("SIOCADDRT");
                               if (install &&
                                   ioctl(s, SIOCDELRT, (char *)&oldroute) < 0)
                                       perror("SIOCDELRT");
                               rt->rt_state &= ~RTS_CHGRT;
                       }
                       if (supplier && (state & (RTS_CHGRT|RTS_ADDRT))) {
                               log("broadcast", rt);
                               msg->rip_cmd = RIPCMD_RESPONSE;
                               msg->rip_nets[0].rip_dst = rt->rt_dst;
                               msg->rip_nets[0].rip_metric =
                                   min(rt->rt_metric+1, HOPCNT_INFINITY);
                               toall(sendmsg);
                       }
               }
       }
       if (doinghost) {
               doinghost = 0;
               base = nethash;
               goto again;
       }
       if (supplier && (timeval % SUPPLY_INTERVAL) == 0)
               toall(supply);
       tprintf("<<< time %d <<<\n", timeval);
       alarm(TIMER_RATE);
}

toall(f)
       int (*f)();
{
       register struct rthash *rh;
       register struct rt_entry *rt;
       register struct sockaddr *dst;
       struct rthash *base = hosthash;
       int doinghost = 1;

again:
       for (rh = base; rh < &base[ROUTEHASHSIZ]; rh++)
       for (rt = rh->rt_forw; rt != (struct rt_entry *)rh; rt = rt->rt_forw) {
               if ((rt->rt_state & RTS_PASSIVE) || rt->rt_metric > 0)
                       continue;
               if (rt->rt_ifp && (rt->rt_ifp->if_flags & IFF_BROADCAST))
                       dst = &rt->rt_ifp->if_broadaddr;
               else
                       dst = &rt->rt_router;
               (*f)(dst, rt->rt_state & RTS_DONTROUTE);
       }
       if (doinghost) {
               base = nethash;
               doinghost = 0;
               goto again;
       }
}

/*ARGSUSED*/
sendmsg(dst, dontroute)
       struct sockaddr *dst;
       int dontroute;
{
       (*afswitch[dst->sa_family].af_output)(s, dst, sizeof (struct rip));
}

supply(dst, dontroute)
       struct sockaddr *dst;
       int dontroute;
{
       register struct rt_entry *rt;
       struct netinfo *n = msg->rip_nets;
       register struct rthash *rh;
       struct rthash *base = hosthash;
       int doinghost = 1, size;
       int (*output)() = afswitch[dst->sa_family].af_output;
       int sto = dontroute ? snoroute : s;

again:
       for (rh = base; rh < &base[ROUTEHASHSIZ]; rh++)
       for (rt = rh->rt_forw; rt != (struct rt_entry *)rh; rt = rt->rt_forw) {
               if (rt->rt_state & RTS_HIDDEN)
                       continue;
               size = (char *)n - packet;
               if (size > MAXPACKETSIZE - sizeof (struct netinfo)) {
                       (*output)(sto, dst, size);
                       n = msg->rip_nets;
               }
               n->rip_dst = rt->rt_dst;
               n->rip_metric = min(rt->rt_metric + 1, HOPCNT_INFINITY);
               n++;
       }
       if (doinghost) {
               doinghost = 0;
               base = nethash;
               goto again;
       }
       if (n != msg->rip_nets)
               (*output)(sto, dst, (char *)n - packet);
}

/*
* Handle an incoming routing packet.
*/
rip_input(from, size)
       struct sockaddr *from;
       int size;
{
       struct rt_entry *rt;
       struct netinfo *n;
       struct ifnet *ifp;
       time_t t;
       int newsize;
       struct afswitch *afp;

       if (trace) {
               if (msg->rip_cmd < RIPCMD_MAX)
                       printf("%s from %x\n", ripcmds[msg->rip_cmd], 
                           ((struct sockaddr_in *)from)->sin_addr);
               else
                       printf("%x from %x\n", msg->rip_cmd,
                           ((struct sockaddr_in *)from)->sin_addr);
       }
       if (from->sa_family >= AF_MAX)
               return;
       afp = &afswitch[from->sa_family];
       switch (msg->rip_cmd) {

       case RIPCMD_REQUEST:
               newsize = 0;
               size -= 4 * sizeof (char);
               n = msg->rip_nets;
               while (size > 0) {
                       if (size < sizeof (struct netinfo))
                               break;
                       size -= sizeof (struct netinfo);

                       /* 
                        * A single entry with sa_family == AF_UNSPEC and
                        * metric ``infinity'' means ``all routes''.
                        */
                       if (n->rip_dst.sa_family == AF_UNSPEC &&
                           n->rip_metric == HOPCNT_INFINITY && size == 0) {
                               supply(from, 0);        /* don't route */
                               return;
                       }
                       rt = rtlookup(&n->rip_dst);
                       n->rip_metric = rt == 0 ? HOPCNT_INFINITY :
                               min(rt->rt_metric+1, HOPCNT_INFINITY);
                       n++, newsize += sizeof (struct netinfo);
               }
               if (newsize > 0) {
                       msg->rip_cmd = RIPCMD_RESPONSE;
                       newsize += sizeof (int);
                       (*afp->af_output)(s, from, newsize);
               }
               return;

       case RIPCMD_TRACEON:
               if ((*afp->af_portcheck)(from) == 0)
                       return;
               if (trace)
                       return;
               packet[size] = '\0';
               ftrace = fopen(msg->rip_tracefile, "a");
               if (ftrace == NULL)
                       return;
               (void) dup2(fileno(ftrace), 1);
               (void) dup2(fileno(ftrace), 2);
               trace = 1;
               t = time(0);
               printf("*** Tracing turned on at %.24s ***\n", ctime(&t));
               return;

       case RIPCMD_TRACEOFF:
               /* verify message came from a priviledged port */
               if ((*afp->af_portcheck)(from) == 0)
                       return;
               if (!trace)
                       return;
               t = time(0);
               printf("*** Tracing turned off at %.24s ***\n", ctime(&t));
               fflush(stdout), fflush(stderr);
               if (ftrace)
                       fclose(ftrace);
               (void) close(1), (void) close(2);
               trace = 0;
               return;

       case RIPCMD_RESPONSE:
               /* verify message came from a router */
               if ((*afp->af_portmatch)(from) == 0)
                       return;
               (*afp->af_canon)(from);
               /* are we talking to ourselves? */
               ifp = if_ifwithaddr(from);
               if (ifp) {
                       rt = rtfind(from, 0);
                       if (rt == 0) {
                               addrouteforif(ifp);
                               return;
                       }
                       /* interface previously thought down? */
                       if (rt->rt_metric > 0) {
                               struct rt_entry *downrt = rtfind(from, 1);
                               if (downrt) {
                                       /* unhide old route and delete other */
                                       downrt->rt_state &= ~RTS_HIDDEN;
                                       downrt->rt_state |= RTS_ADDRT;
                                       rt->rt_state |= RTS_DELRT;
                                       log("unhide", downrt);
                               }
                       }
                       rt->rt_timer = 0;
                       return;
               }
               size -= 4 * sizeof (char);
               n = msg->rip_nets;
               for (; size > 0; size -= sizeof (struct netinfo), n++) {
                       if (size < sizeof (struct netinfo))
                               break;
                       if (n->rip_metric >= HOPCNT_INFINITY)
                               continue;
                       tprintf("dst %x hc %d...",
                           ((struct sockaddr_in *)&n->rip_dst)->sin_addr,
                           n->rip_metric);
                       rt = rtlookup(&n->rip_dst);
                       if (rt == 0) {
                               rtadd(&n->rip_dst, from, n->rip_metric, 0);
                               continue;
                       }
                       tprintf("ours: gate %x hc %d timer %d\n",
                         ((struct sockaddr_in *)&rt->rt_router)->sin_addr,
                         rt->rt_metric, rt->rt_timer);

                       /*
                        * update if from gateway, shorter, or getting
                        * stale and equivalent.
                        */
                       if (equal(from, &rt->rt_router) ||
                           n->rip_metric < rt->rt_metric ||
                           (rt->rt_timer > (EXPIRE_TIME/2) &&
                           rt->rt_metric == n->rip_metric)) {
                               rtchange(rt, from, n->rip_metric);
                               rt->rt_timer = 0;
                       }
               }
               return;
       }
       printf("bad packet, cmd=%x\n", msg->rip_cmd);
}

struct rt_entry *
rtlookup(dst)
       struct sockaddr *dst;
{
       register struct rt_entry *rt;
       register struct rthash *rh;
       register int hash;
       struct afhash h;
       int doinghost = 1;

       if (dst->sa_family >= AF_MAX)
               return (0);
       (*afswitch[dst->sa_family].af_hash)(dst, &h);
       hash = h.afh_hosthash;
       rh = &hosthash[hash % ROUTEHASHSIZ];
again:
       for (rt = rh->rt_forw; rt != (struct rt_entry *)rh; rt = rt->rt_forw) {
               if (rt->rt_hash != hash || (rt->rt_state & RTS_HIDDEN))
                       continue;
               if (equal(&rt->rt_dst, dst))
                       return (rt);
       }
       if (doinghost) {
               doinghost = 0;
               hash = h.afh_nethash;
               rh = &nethash[hash % ROUTEHASHSIZ];
               goto again;
       }
       return (0);
}

struct rt_entry *
rtfind(dst, lookfordownif)
       struct sockaddr *dst;
       int lookfordownif;
{
       register struct rt_entry *rt;
       register struct rthash *rh;
       register int hash;
       struct afhash h;
       int af = dst->sa_family;
       int doinghost = 1, (*match)();

       if (af >= AF_MAX)
               return (0);
       (*afswitch[af].af_hash)(dst, &h);
       hash = h.afh_hosthash;
       rh = &hosthash[hash % ROUTEHASHSIZ];

again:
       for (rt = rh->rt_forw; rt != (struct rt_entry *)rh; rt = rt->rt_forw) {
               if (rt->rt_hash != hash)
                       continue;
               if (lookfordownif ^ (rt->rt_state & RTS_HIDDEN))
                       continue;
               if (doinghost) {
                       if (equal(&rt->rt_dst, dst))
                               return (rt);
               } else {
                       if (rt->rt_dst.sa_family == af &&
                           (*match)(&rt->rt_dst, dst))
                               return (rt);
               }
       }
       if (doinghost) {
               doinghost = 0;
               hash = h.afh_nethash;
               rh = &nethash[hash % ROUTEHASHSIZ];
               match = afswitch[af].af_netmatch;
               goto again;
       }
       return (0);
}

rtadd(dst, gate, metric, state)
       struct sockaddr *dst, *gate;
       int metric, state;
{
       struct afhash h;
       register struct rt_entry *rt;
       struct rthash *rh;
       int af = dst->sa_family, flags, hash;

       if (af >= AF_MAX)
               return;
       (*afswitch[af].af_hash)(dst, &h);
       flags = (*afswitch[af].af_checkhost)(dst) ? RTF_HOST : 0;
       if (flags & RTF_HOST) {
               hash = h.afh_hosthash;
               rh = &hosthash[hash % ROUTEHASHSIZ];
       } else {
               hash = h.afh_nethash;
               rh = &nethash[hash % ROUTEHASHSIZ];
       }
       rt = (struct rt_entry *)malloc(sizeof (*rt));
       if (rt == 0)
               return;
       rt->rt_hash = hash;
       rt->rt_dst = *dst;
       rt->rt_router = *gate;
       rt->rt_metric = metric;
       rt->rt_timer = 0;
       rt->rt_flags = RTF_UP | flags;
       rt->rt_state = state;
       rt->rt_ifp = if_ifwithnet(&rt->rt_router);
       if (metric)
               rt->rt_flags |= RTF_GATEWAY;
       insque(rt, rh);
       log("add", rt);
       if (install)
               rt->rt_state |= RTS_ADDRT;
}

rtchange(rt, gate, metric)
       struct rt_entry *rt;
       struct sockaddr *gate;
       short metric;
{
       int doioctl = 0, metricchanged = 0;

       if (!equal(&rt->rt_router, gate)) {
               if (rt->rt_state & RTS_DONTDELETE) {
                       rtadd(&rt->rt_dst, gate, metric,
                          rt->rt_state &~ (RTS_DONTDELETE|RTS_DONTROUTE));
                       rt->rt_state |= RTS_DELRT;
                       return;
               }
               doioctl++;
       }
       if (metric != rt->rt_metric) {
               metricchanged++;
               rt->rt_metric = metric;
       }
       if (doioctl) {
               if ((rt->rt_state & RTS_CHGRT) == 0)
                       rt->rt_oldrouter = rt->rt_router;
               rt->rt_router = *gate;
               rt->rt_state |= RTS_CHGRT;
       }
       if (doioctl || metricchanged)
               log("change", rt);
}

rtdelete(rt)
       struct rt_entry *rt;
{

       log("delete", rt);
       if (install && ioctl(s, SIOCDELRT, (char *)&rt->rt_rt))
               perror("SIOCDELRT");
       if (rt->rt_state & RTS_DONTDELETE) {
               rt->rt_state |= RTS_HIDDEN;
               return;
       }
       remque(rt);
       free((char *)rt);
}

log(operation, rt)
       char *operation;
       struct rt_entry *rt;
{
       struct sockaddr_in *dst, *gate;
       static struct bits {
               int     t_bits;
               char    *t_name;
       } flagbits[] = {
               { RTF_UP,       "UP" },
               { RTF_GATEWAY,  "GATEWAY" },
               { RTF_HOST,     "HOST" },
               { 0 }
       }, statebits[] = {
               { RTS_ADDRT,    "ADD" },
               { RTS_DELRT,    "DELETE" },
               { RTS_CHGRT,    "CHANGE" },
               { RTS_PASSIVE,  "PASSIVE" },
               { RTS_DONTDELETE,"DONTDELETE" },
               { RTS_DONTROUTE,"DONTROUTE" },
               { RTS_HIDDEN,   "HIDDEN" },
               { 0 }
       };
       register struct bits *p;
       register int first;
       char *cp;

       if (trace == 0)
               return;
       printf("%s ", operation);
       dst = (struct sockaddr_in *)&rt->rt_dst;
       gate = (struct sockaddr_in *)&rt->rt_router;
       printf("dst %x, router %x", dst->sin_addr, gate->sin_addr);
       if (rt->rt_state & RTS_CHGRT)
               printf(" (old %x)",
                       ((struct sockaddr_in *)&rt->rt_oldrouter)->sin_addr);
       printf(", metric %d, flags", rt->rt_metric);
       cp = " %s";
       for (first = 1, p = flagbits; p->t_bits > 0; p++) {
               if ((rt->rt_flags & p->t_bits) == 0)
                       continue;
               printf(cp, p->t_name);
               if (first) {
                       cp = "|%s";
                       first = 0;
               }
       }
       printf(" state");
       cp = " %s";
       for (first = 1, p = statebits; p->t_bits > 0; p++) {
               if ((rt->rt_state & p->t_bits) == 0)
                       continue;
               printf(cp, p->t_name);
               if (first) {
                       cp = "|%s";
                       first = 0;
               }
       }
       putchar('\n');
}

struct ifnet *
if_ifwithaddr(addr)
       struct sockaddr *addr;
{
       register struct ifnet *ifp;

#define same(a1, a2) \
       (bcmp((caddr_t)((a1)->sa_data), (caddr_t)((a2)->sa_data), 14) == 0)
       for (ifp = ifnet; ifp; ifp = ifp->if_next) {
               if (ifp->if_addr.sa_family != addr->sa_family)
                       continue;
               if (same(&ifp->if_addr, addr))
                       break;
               if ((ifp->if_flags & IFF_BROADCAST) &&
                   same(&ifp->if_broadaddr, addr))
                       break;
       }
       return (ifp);
#undef same
}

struct ifnet *
if_ifwithnet(addr)
       register struct sockaddr *addr;
{
       register struct ifnet *ifp;
       register int af = addr->sa_family;
       register int (*netmatch)();

       if (af >= AF_MAX)
               return (0);
       netmatch = afswitch[af].af_netmatch;
       for (ifp = ifnet; ifp; ifp = ifp->if_next) {
               if (af != ifp->if_addr.sa_family)
                       continue;
               if ((*netmatch)(addr, &ifp->if_addr))
                       break;
       }
       return (ifp);
}

struct in_addr
if_makeaddr(net, host)
       int net, host;
{
       u_long addr;

       if (net < 128)
               addr = (net << 24) | host;
       else if (net < 65536)
               addr = (net << 16) | host;
       else
               addr = (net << 8) | host;
#ifdef vax
       addr = htonl(addr);
#endif
       return (*(struct in_addr *)&addr);
}