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NetBSD/sbin/routed/input.c

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/* $NetBSD: input.c,v 1.18 1996/09/24 16:24:14 christos Exp $ */
/*
* Copyright (c) 1983, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if !defined(lint) && !defined(sgi) && !defined(__NetBSD__)
static char sccsid[] = "@(#)input.c 8.1 (Berkeley) 6/5/93";
#elif defined(__NetBSD__)
static char rcsid[] = "$NetBSD: input.c,v 1.18 1996/09/24 16:24:14 christos Exp $";
#endif
#include "defs.h"
static void input(struct sockaddr_in *, struct interface*, struct rip *, int);
static void input_route(struct interface *, naddr,
naddr, naddr, naddr, struct netinfo *);
/* process RIP input
*/
void
read_rip(int sock,
struct interface *ifp)
{
struct sockaddr_in from;
int fromlen, cc;
union pkt_buf inbuf;
for (;;) {
fromlen = sizeof(from);
cc = recvfrom(sock, &inbuf, sizeof(inbuf), 0,
(struct sockaddr*)&from, &fromlen);
if (cc <= 0) {
if (cc < 0 && errno != EWOULDBLOCK)
LOGERR("recvfrom(rip)");
break;
}
if (fromlen != sizeof(struct sockaddr_in))
logbad(1,"impossible recvfrom(rip) fromlen=%d",
fromlen);
input(&from, ifp, &inbuf.rip, cc);
}
}
/* Process a RIP packet
*/
static void
input(struct sockaddr_in *from, /* received from this IP address */
struct interface *sifp, /* interface by which it arrived */
struct rip *rip,
int size)
{
# define FROM_NADDR from->sin_addr.s_addr
static naddr use_auth, bad_len, bad_mask;
static naddr unk_router, bad_router, bad_nhop;
struct interface *aifp; /* interface if via 1 hop */
struct rt_entry *rt;
struct netinfo *n, *lim;
struct interface *ifp1;
naddr gate, mask, v1_mask, dst, ddst_h;
int i;
aifp = iflookup(from->sin_addr.s_addr);
if (sifp == 0)
sifp = aifp;
if (sifp != 0)
sifp->int_state |= IS_ACTIVE;
trace_rip("Recv", "from", from, sifp, rip, size);
if (rip->rip_vers == 0) {
if (from->sin_addr.s_addr != bad_router)
msglog("RIP version 0, cmd %d, packet received"
" from %s",
rip->rip_cmd, naddr_ntoa(FROM_NADDR));
bad_router = from->sin_addr.s_addr;
return;
} else if (rip->rip_vers > RIPv2) {
rip->rip_vers = RIPv2;
}
if (size > MAXPACKETSIZE) {
if (from->sin_addr.s_addr != bad_router)
msglog("packet at least %d bytes too long received"
" from %s",
size-MAXPACKETSIZE, naddr_ntoa(FROM_NADDR));
bad_router = from->sin_addr.s_addr;
return;
}
n = rip->rip_nets;
lim = (struct netinfo *)((char*)rip + size);
/* Notice authentication.
* As required by section 4.2 in RFC 1723, discard authenticated
* RIPv2 messages, but only if configured for that silliness.
*
* RIPv2 authentication is lame, since snooping on the wire makes
* its simple passwords evident. Also, why authenticate queries?
* Why should a RIPv2 implementation with authentication disabled
* not be able to listen to RIPv2 packets with authenication, while
* RIPv1 systems will listen? Crazy!
*/
if (!auth_ok
&& rip->rip_vers == RIPv2
&& n < lim && n->n_family == RIP_AF_AUTH) {
if (from->sin_addr.s_addr != use_auth)
msglog("RIPv2 message with authentication"
" from %s discarded",
naddr_ntoa(FROM_NADDR));
use_auth = from->sin_addr.s_addr;
trace_pkt("discard authenticated RIPv2 message\n");
return;
}
switch (rip->rip_cmd) {
case RIPCMD_REQUEST:
/* did the request come from a router?
*/
if (from->sin_port == htons(RIP_PORT)) {
/* yes, ignore it if RIP is off so that it does not
* depend on us.
*/
if (rip_sock < 0) {
trace_pkt("ignore request while RIP off\n");
return;
}
/* Ignore the request if we talking to ourself
* (and not a remote gateway).
*/
if (ifwithaddr(FROM_NADDR, 0, 0) != 0) {
trace_pkt("discard our own RIP request\n");
return;
}
}
/* According to RFC 1723, we should ignore unathenticated
* queries. That is too silly to bother with. Sheesh!
* Are forwarding tables supposed to be secret? When
* a bad guy can infer them with test traffic?
* Maybe on firewalls you'd care, but not enough to
* give up the diagnostic facilities of remote probing.
*/
if (n >= lim
|| size%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
if (from->sin_addr.s_addr != bad_len)
msglog("request of bad length (%d) from %s",
size, naddr_ntoa(FROM_NADDR));
bad_len = from->sin_addr.s_addr;
}
for (; n < lim; n++) {
n->n_metric = ntohl(n->n_metric);
/* A single entry with family RIP_AF_UNSPEC and
* metric HOPCNT_INFINITY means "all routes".
* We respond to routers only if we are acting
* as a supplier, or to anyone other than a router
* (i.e. a query).
*/
if (n->n_family == RIP_AF_UNSPEC
&& n->n_metric == HOPCNT_INFINITY
&& n == rip->rip_nets
&& n+1 == lim) {
if (from->sin_port != htons(RIP_PORT)) {
/* Answer a query from a utility
* program with all we know.
*/
supply(from, sifp, OUT_QUERY, 0,
rip->rip_vers);
return;
}
/* A router trying to prime its tables.
* Filter the answer in the about same way
* broadcasts are filtered.
*
* Only answer a router if we are a supplier
* to keep an unwary host that is just starting
* from picking us as a router. Respond with
* RIPv1 instead of RIPv2 if that is what we
* are broadcasting on the interface to keep
* the remote router from getting the wrong
* initial idea of the routes we send.
*/
if (!supplier
|| aifp == 0
|| (aifp->int_state & IS_PASSIVE)
|| (aifp->int_state & IS_ALIAS)
|| ((aifp->int_state & IS_NO_RIPV1_OUT)
&& (aifp->int_state&IS_NO_RIPV2_OUT)))
return;
supply(from, aifp, OUT_UNICAST, 0,
(aifp->int_state&IS_NO_RIPV1_OUT)
? RIPv2 : RIPv1);
return;
}
if (n->n_family != RIP_AF_INET) {
if (from->sin_addr.s_addr != bad_router)
msglog("request from %s"
" for unsupported (af %d) %s",
naddr_ntoa(FROM_NADDR),
ntohs(n->n_family),
naddr_ntoa(n->n_dst));
bad_router = from->sin_addr.s_addr;
return;
}
dst = n->n_dst;
if (!check_dst(dst)) {
if (from->sin_addr.s_addr != bad_router)
msglog("bad queried destination"
" %s from %s",
naddr_ntoa(dst),
naddr_ntoa(FROM_NADDR));
bad_router = from->sin_addr.s_addr;
return;
}
if (rip->rip_vers == RIPv1
|| 0 == (mask = ntohl(n->n_mask))
|| 0 != (ntohl(dst) & ~mask))
mask = ripv1_mask_host(dst,sifp);
rt = rtget(dst, mask);
if (!rt && dst != RIP_DEFAULT)
rt = rtfind(n->n_dst);
n->n_tag = 0;
n->n_nhop = 0;
if (rip->rip_vers == RIPv1) {
n->n_mask = 0;
} else {
n->n_mask = mask;
}
if (rt == 0) {
n->n_metric = HOPCNT_INFINITY;
} else {
n->n_metric = rt->rt_metric+1;
n->n_metric += (sifp!=0)?sifp->int_metric : 1;
if (n->n_metric > HOPCNT_INFINITY)
n->n_metric = HOPCNT_INFINITY;
if (rip->rip_vers != RIPv1) {
n->n_tag = rt->rt_tag;
if (sifp != 0
&& on_net(rt->rt_gate,
sifp->int_net,
sifp->int_mask)
&& rt->rt_gate != sifp->int_addr)
n->n_nhop = rt->rt_gate;
}
}
HTONL(n->n_metric);
}
/* Answer about specific routes.
* Only answer a router if we are a supplier
* to keep an unwary host that is just starting
* from picking us an a router.
*/
rip->rip_cmd = RIPCMD_RESPONSE;
rip->rip_res1 = 0;
if (rip->rip_vers != RIPv1)
rip->rip_vers = RIPv2;
if (from->sin_port != htons(RIP_PORT)) {
/* query */
(void)output(OUT_QUERY, from, sifp, rip, size);
} else if (supplier) {
(void)output(OUT_UNICAST, from, sifp, rip, size);
}
return;
case RIPCMD_TRACEON:
case RIPCMD_TRACEOFF:
/* verify message came from a privileged port */
if (ntohs(from->sin_port) > IPPORT_RESERVED) {
msglog("trace command from untrusted port on %s",
naddr_ntoa(FROM_NADDR));
return;
}
if (aifp == 0) {
msglog("trace command from unknown router %s",
naddr_ntoa(FROM_NADDR));
return;
}
if (rip->rip_cmd == RIPCMD_TRACEON) {
rip->rip_tracefile[size-4] = '\0';
trace_on((char*)rip->rip_tracefile, 0);
} else {
trace_off("tracing turned off by %s\n",
naddr_ntoa(FROM_NADDR));
}
return;
case RIPCMD_RESPONSE:
if (size%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
if (from->sin_addr.s_addr != bad_len)
msglog("response of bad length (%d) from %s",
size, naddr_ntoa(FROM_NADDR));
bad_len = from->sin_addr.s_addr;
}
/* verify message came from a router */
if (from->sin_port != ntohs(RIP_PORT)) {
trace_pkt("discard RIP response from unknown port\n");
return;
}
if (rip_sock < 0) {
trace_pkt("discard response while RIP off\n");
return;
}
/* Are we talking to ourself or a remote gateway?
*/
ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
if (ifp1) {
if (ifp1->int_state & IS_REMOTE) {
if (ifp1->int_state & IS_PASSIVE) {
msglog("bogus input from %s on"
" supposedly passive %s",
naddr_ntoa(FROM_NADDR),
ifp1->int_name);
} else {
ifp1->int_act_time = now.tv_sec;
if (if_ok(ifp1, "remote "))
addrouteforif(ifp1);
}
} else {
trace_pkt("discard our own RIP response\n");
}
return;
}
/* Check the router from which message originated. We accept
* routing packets from routers directly connected via
* broadcast or point-to-point networks, and from
* those listed in /etc/gateways.
*/
if (!aifp) {
if (from->sin_addr.s_addr != unk_router)
msglog("discard packet from unknown router %s"
" or via unidentified interface",
naddr_ntoa(FROM_NADDR));
unk_router = from->sin_addr.s_addr;
return;
}
if (aifp->int_state & IS_PASSIVE) {
trace_act("discard packet from %s"
" via passive interface %s\n",
naddr_ntoa(FROM_NADDR),
aifp->int_name);
return;
}
/* Check required version
*/
if (((aifp->int_state & IS_NO_RIPV1_IN)
&& rip->rip_vers == RIPv1)
|| ((aifp->int_state & IS_NO_RIPV2_IN)
&& rip->rip_vers != RIPv1)) {
trace_pkt("discard RIPv%d response\n",
rip->rip_vers);
return;
}
/* Ignore routes via dead interface.
*/
if (aifp->int_state & IS_BROKE) {
trace_pkt("discard response via broken interface %s\n",
aifp->int_name);
return;
}
/* Authenticate the packet if we have a secret.
*/
if (aifp->int_passwd[0] != '\0') {
if (n >= lim
|| n->n_family != RIP_AF_AUTH
|| ((struct netauth*)n)->a_type != RIP_AUTH_PW) {
if (from->sin_addr.s_addr != use_auth)
msglog("missing password from %s",
naddr_ntoa(FROM_NADDR));
use_auth = from->sin_addr.s_addr;
return;
} else if (0 != bcmp(((struct netauth*)n)->au.au_pw,
aifp->int_passwd,
sizeof(aifp->int_passwd))) {
if (from->sin_addr.s_addr != use_auth)
msglog("bad password from %s",
naddr_ntoa(FROM_NADDR));
use_auth = from->sin_addr.s_addr;
return;
}
}
auth_ok:
for (; n < lim; n++) {
if (n->n_family == RIP_AF_AUTH)
continue;
NTOHL(n->n_metric);
dst = n->n_dst;
if (n->n_family != RIP_AF_INET
&& (n->n_family != RIP_AF_UNSPEC
|| dst != RIP_DEFAULT)) {
if (from->sin_addr.s_addr != bad_router)
msglog("route from %s to unsupported"
" address family %d,"
" destination %s",
naddr_ntoa(FROM_NADDR),
n->n_family,
naddr_ntoa(dst));
bad_router = from->sin_addr.s_addr;
continue;
}
if (!check_dst(dst)) {
if (from->sin_addr.s_addr != bad_router)
msglog("bad destination %s from %s",
naddr_ntoa(dst),
naddr_ntoa(FROM_NADDR));
bad_router = from->sin_addr.s_addr;
return;
}
if (n->n_metric == 0
|| n->n_metric > HOPCNT_INFINITY) {
if (from->sin_addr.s_addr != bad_router)
msglog("bad metric %d from %s"
" for destination %s",
n->n_metric,
naddr_ntoa(FROM_NADDR),
naddr_ntoa(dst));
bad_router = from->sin_addr.s_addr;
return;
}
/* Notice the next-hop.
*/
gate = from->sin_addr.s_addr;
if (n->n_nhop != 0) {
if (rip->rip_vers == RIPv2) {
n->n_nhop = 0;
} else {
/* Use it only if it is valid. */
if (on_net(n->n_nhop,
aifp->int_net, aifp->int_mask)
&& check_dst(n->n_nhop)) {
gate = n->n_nhop;
} else {
if (bad_nhop != from->sin_addr.s_addr)
msglog("router %s to %s has"
" bad next hop %s",
naddr_ntoa(FROM_NADDR),
naddr_ntoa(dst),
naddr_ntoa(n->n_nhop));
bad_nhop = from->sin_addr.s_addr;
n->n_nhop = 0;
}
}
}
if (rip->rip_vers == RIPv1
|| 0 == (mask = ntohl(n->n_mask))) {
mask = ripv1_mask_host(dst,aifp);
} else if ((ntohl(dst) & ~mask) != 0) {
if (bad_mask != from->sin_addr.s_addr) {
msglog("router %s sent bad netmask"
" %#x with %s",
naddr_ntoa(FROM_NADDR),
mask,
naddr_ntoa(dst));
bad_mask = from->sin_addr.s_addr;
}
continue;
}
if (rip->rip_vers == RIPv1)
n->n_tag = 0;
/* Adjust metric according to incoming interface..
*/
n->n_metric += aifp->int_metric;
if (n->n_metric > HOPCNT_INFINITY)
n->n_metric = HOPCNT_INFINITY;
/* Recognize and ignore a default route we faked
* which is being sent back to us by a machine with
* broken split-horizon.
* Be a little more paranoid than that, and reject
* default routes with the same metric we advertised.
*/
if (aifp->int_d_metric != 0
&& dst == RIP_DEFAULT
&& n->n_metric >= aifp->int_d_metric)
continue;
/* We can receive aggregated RIPv2 routes that must
* be broken down before they are transmitted by
* RIPv1 via an interface on a subnet.
* We might also receive the same routes aggregated
* via other RIPv2 interfaces.
* This could cause duplicate routes to be sent on
* the RIPv1 interfaces. "Longest matching variable
* length netmasks" lets RIPv2 listeners understand,
* but breaking down the aggregated routes for RIPv1
* listeners can produce duplicate routes.
*
* Breaking down aggregated routes here bloats
* the daemon table, but does not hurt the kernel
* table, since routes are always aggregated for
* the kernel.
*
* Notice that this does not break down network
* routes corresponding to subnets. This is part
* of the defense against RS_NET_SYN.
*/
if (have_ripv1_out
&& (v1_mask = ripv1_mask_net(dst,0)) > mask
&& (((rt = rtget(dst,mask)) == 0
|| !(rt->rt_state & RS_NET_SYN)))) {
ddst_h = v1_mask & -v1_mask;
i = (v1_mask & ~mask)/ddst_h;
if (i >= 511) {
/* Punt if we would have to generate
* an unreasonable number of routes.
*/
#ifdef DEBUG
msglog("accept %s from %s as 1"
" instead of %d routes",
addrname(dst,mask,0),
naddr_ntoa(FROM_NADDR),
i+1);
#endif
i = 0;
} else {
mask = v1_mask;
}
} else {
i = 0;
}
for (;;) {
input_route(aifp, FROM_NADDR,
dst, mask, gate, n);
if (i-- == 0)
break;
dst = htonl(ntohl(dst) + ddst_h);
}
}
break;
}
}
/* Process a single input route.
*/
static void
input_route(struct interface *ifp,
naddr from,
naddr dst,
naddr mask,
naddr gate,
struct netinfo *n)
{
int i;
struct rt_entry *rt;
struct rt_spare *rts, *rts0;
struct interface *ifp1;
time_t new_time;
/* See if the other guy is telling us to send our packets to him.
* Sometimes network routes arrive over a point-to-point link for
* the network containing the address(es) of the link.
*
* If our interface is broken, switch to using the other guy.
*/
ifp1 = ifwithaddr(dst, 1, 1);
if (ifp1 != 0
&& !(ifp1->int_state & IS_BROKE))
return;
/* Look for the route in our table.
*/
rt = rtget(dst, mask);
/* Consider adding the route if we do not already have it.
*/
if (rt == 0) {
/* Ignore unknown routes being poisoned.
*/
if (n->n_metric == HOPCNT_INFINITY)
return;
/* Ignore the route if it points to us */
if (n->n_nhop != 0
&& 0 != ifwithaddr(n->n_nhop, 1, 0))
return;
/* If something has not gone crazy and tried to fill
* our memory, accept the new route.
*/
if (total_routes < MAX_ROUTES)
rtadd(dst, mask, gate, from, n->n_metric,
n->n_tag, 0, ifp);
return;
}
/* We already know about the route. Consider this update.
*
* If (rt->rt_state & RS_NET_SYN), then this route
* is the same as a network route we have inferred
* for subnets we know, in order to tell RIPv1 routers
* about the subnets.
*
* It is impossible to tell if the route is coming
* from a distant RIPv2 router with the standard
* netmask because that router knows about the entire
* network, or if it is a round-about echo of a
* synthetic, RIPv1 network route of our own.
* The worst is that both kinds of routes might be
* received, and the bad one might have the smaller
* metric. Partly solve this problem by never
* aggregating into such a route. Also keep it
* around as long as the interface exists.
*/
rts0 = rt->rt_spares;
for (rts = rts0, i = NUM_SPARES; i != 0; i--, rts++) {
if (rts->rts_router == from)
break;
/* Note the worst slot to reuse,
* other than the current slot.
*/
if (rts0 == rt->rt_spares
|| BETTER_LINK(rt, rts0, rts))
rts0 = rts;
}
if (i != 0) {
/* Found the router
*/
int old_metric = rts->rts_metric;
/* Keep poisoned routes around only long enough to pass
* the poison on. Get a new timestamp for good routes.
*/
new_time =((old_metric == HOPCNT_INFINITY)
? rts->rts_time
: now.tv_sec);
/* If this is an update for the router we currently prefer,
* then note it.
*/
if (i == NUM_SPARES) {
rtchange(rt,rt->rt_state, gate,rt->rt_router,
n->n_metric, n->n_tag, ifp, new_time, 0);
/* If the route got worse, check for something better.
*/
if (n->n_metric > old_metric)
rtswitch(rt, 0);
return;
}
/* This is an update for a spare route.
* Finished if the route is unchanged.
*/
if (rts->rts_gate == gate
&& old_metric == n->n_metric
&& rts->rts_tag == n->n_tag) {
rts->rts_time = new_time;
return;
}
} else {
/* The update is for a route we know about,
* but not from a familiar router.
*
* Ignore the route if it points to us.
*/
if (n->n_nhop != 0
&& 0 != ifwithaddr(n->n_nhop, 1, 0))
return;
rts = rts0;
/* Save the route as a spare only if it has
* a better metric than our worst spare.
* This also ignores poisoned routes (those
* received with metric HOPCNT_INFINITY).
*/
if (n->n_metric >= rts->rts_metric)
return;
new_time = now.tv_sec;
}
trace_upslot(rt, rts, gate, from, ifp, n->n_metric,n->n_tag, new_time);
rts->rts_gate = gate;
rts->rts_router = from;
rts->rts_metric = n->n_metric;
rts->rts_tag = n->n_tag;
rts->rts_time = new_time;
rts->rts_ifp = ifp;
/* try to switch to a better route */
rtswitch(rt, rts);
}
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