Bug 31045

        my routed dumps core when I do an rtquery on it's xl1
        interface.  My /etc/gateways:
          if=xl1 no_rip no_rdisc
          if=xl0 pm_rdisc

        routed is started as "routed -s" to force it to act like a 
        gateway.

        Here's the trace:

12:30:41{{ttyp0}root@arthur}/sbin//> gdb /sbin/routed /routed.core
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This GDB was configured as "alpha-unknown-freebsd"...
Core was generated by `routed'.
Program terminated with signal 11, Segmentation fault.
#0  0x1200088bc in supply (dst=0x120079b40, ifp=0x0, type=OUT_QUERY, flash=0,
    vers=2, passwd_ok=0) at /usr/src/sbin/routed/output.c:767
767             if (supplier && (def_metric = ifp->int_d_metric) != 0) {
(gdb) bt
#0  0x1200088bc in supply (dst=0x120079b40, ifp=0x0, type=OUT_QUERY, flash=0,
    vers=2, passwd_ok=0) at /usr/src/sbin/routed/output.c:767
(gdb) print ifp
$1 = (struct interface *) 0x0
(gdb) print *rt
$2 = {rt_nodes = {{rn_mklist = 0x0, rn_p = 0x0, rn_b = 0, rn_bmask = 0 '\000',
      rn_flags = 0 '\000', rn_u = {rn_leaf = {rn_Key = 0x0, rn_Mask = 0x0,
          rn_Dupedkey = 0x0}, rn_node = {rn_Off = 0, rn_L = 0x0,
          rn_R = 0x0}}}, {rn_mklist = 0x0, rn_p = 0x0, rn_b = 0,
      rn_bmask = 0 '\000', rn_flags = 0 '\000', rn_u = {rn_leaf = {
          rn_Key = 0x0, rn_Mask = 0x0, rn_Dupedkey = 0x0}, rn_node = {
          rn_Off = 0, rn_L = 0x0, rn_R = 0x0}}}}, rt_state = 0, rt_dst_sock = {
    sin_len = 0 '\000', sin_family = 0 '\000', sin_port = 0, sin_addr = {
      s_addr = 0}, sin_zero = "\000\000\000\000\000\000\000"}, rt_mask = 0,
  rt_spares = {{rts_ifp = 0x0, rts_gate = 0, rts_router = 0,
      rts_metric = 0 '\000', rts_tag = 0, rts_time = 0, rts_de_ag = 0}, {
      rts_ifp = 0x0, rts_gate = 0, rts_router = 0, rts_metric = 0 '\000',
      rts_tag = 0, rts_time = 0, rts_de_ag = 0}, {rts_ifp = 0x0, rts_gate = 0,
      rts_router = 0, rts_metric = 0 '\000', rts_tag = 0, rts_time = 0,
      rts_de_ag = 0}, {rts_ifp = 0x0, rts_gate = 0, rts_router = 0,
      rts_metric = 0 '\000', rts_tag = 0, rts_time = 0, rts_de_ag = 0}},
  rt_seqno = 0, rt_poison_metric = 0 '\000', rt_poison_time = 0}

Seems like "rtfind(dst->sin_addr.s_addr)" fails in the beginning of
supply() in output.c, and ifp is assigned a NULL pointer.

Fix: 

I suppose have supply() do some bounds checking and then fail
        accordingly, but I don't even know what supply() does, so
        wouldn't know how to do that.

        Other configuration info available upon request.
How-To-Repeat:         Do same setup as described at the beginning of "Description:"
        and do an rtquery from an external host.