more consistency checks; watch those unsigned moduli

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

#ifndef lint
static char sccsid[] = "@(#)input.c     4.6 (Berkeley) %G%";
#endif

/*
* Routing Table Management Daemon
*/
#include "defs.h"

/*
* Process a newly received packet.
*/
rip_input(from, size)
       struct sockaddr *from;
       int size;
{
       struct rt_entry *rt;
       struct netinfo *n;
       struct interface *ifp;
       int newsize;
       struct afswitch *afp;

       ifp = 0;
       TRACE_INPUT(ifp, from, size);
       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);

                       if (msg->rip_vers > 0) {
                               n->rip_dst.sa_family =
                                       ntohs(n->rip_dst.sa_family);
                               n->rip_metric = ntohl(n->rip_metric);
                       }
                       /* 
                        * 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, ifp);
                               return;
                       }
                       rt = rtlookup(&n->rip_dst);
                       n->rip_metric = rt == 0 ? HOPCNT_INFINITY :
                               min(rt->rt_metric+1, HOPCNT_INFINITY);
                       if (msg->rip_vers > 0) {
                               n->rip_dst.sa_family =
                                       htons(n->rip_dst.sa_family);
                               n->rip_metric = htonl(n->rip_metric);
                       }
                       n++, newsize += sizeof (struct netinfo);
               }
               if (newsize > 0) {
                       msg->rip_cmd = RIPCMD_RESPONSE;
                       newsize += sizeof (int);
                       (*afp->af_output)(s, 0, from, newsize);
               }
               return;

       case RIPCMD_TRACEON:
       case RIPCMD_TRACEOFF:
               /* verify message came from a priviledged port */
               if ((*afp->af_portcheck)(from) == 0)
                       return;
               packet[size] = '\0';
               if (msg->rip_cmd == RIPCMD_TRACEON)
                       traceon(msg->rip_tracefile);
               else
                       traceoff();
               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);
                       if (rt == 0)
                               addrouteforif(ifp);
                       else
                               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 (msg->rip_vers > 0) {
                               n->rip_dst.sa_family =
                                       ntohs(n->rip_dst.sa_family);
                               n->rip_metric = ntohl(n->rip_metric);
                       }
                       if ((unsigned) n->rip_metric >= HOPCNT_INFINITY)
                               continue;
                       if (((*afp->af_checkhost)(&n->rip_dst)) == 0)
                               continue;
                       rt = rtlookup(&n->rip_dst);
                       if (rt == 0) {
                               rtadd(&n->rip_dst, from, n->rip_metric, 0);
                               continue;
                       }

                       /*
                        * Update if from gateway, shorter, or getting
                        * stale and equivalent.
                        */
                       if (equal(from, &rt->rt_router) ||
                           (unsigned) 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;
       }
}