715 lines
20 KiB
C
715 lines
20 KiB
C
/*
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* Copyright (c) 1983, 1988, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if !defined(lint) && !defined(sgi) && !defined(__NetBSD__)
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static char sccsid[] = "@(#)input.c 8.1 (Berkeley) 6/5/93";
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#elif defined(__NetBSD__)
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static char rcsid[] = "$NetBSD$";
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#endif
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#ident "$Revision: 1.1.3.3 $"
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#include "defs.h"
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static void input(struct sockaddr_in *, struct interface*, struct rip *, int);
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static void input_route(struct interface *, naddr,
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naddr, naddr, naddr, struct netinfo *);
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/* process RIP input
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*/
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void
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read_rip(int sock,
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struct interface *ifp)
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{
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struct sockaddr_in from;
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int fromlen, cc;
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union pkt_buf inbuf;
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for (;;) {
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fromlen = sizeof(from);
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cc = recvfrom(sock, &inbuf, sizeof(inbuf), 0,
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(struct sockaddr*)&from, &fromlen);
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if (cc <= 0) {
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if (cc < 0 && errno != EWOULDBLOCK)
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LOGERR("recvfrom(rip)");
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break;
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}
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if (fromlen != sizeof(struct sockaddr_in))
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logbad(1,"impossible recvfrom(rip) fromlen=%d",
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fromlen);
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input(&from,
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(ifp != 0) ? ifp : iflookup(from.sin_addr.s_addr),
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&inbuf.rip, cc);
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}
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}
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/* Process a RIP packet
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*/
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static void
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input(struct sockaddr_in *from, /* received from this IP address */
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struct interface *ifp,
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struct rip *rip,
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int size)
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{
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# define FROM_NADDR from->sin_addr.s_addr
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static naddr use_auth, bad_len, bad_mask;
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static naddr unk_router, bad_router, bad_nhop;
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struct rt_entry *rt;
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struct netinfo *n, *lim;
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struct interface *ifp1;
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naddr gate, mask, v1_mask, dst, ddst_h;
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int i;
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if (ifp != 0)
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ifp->int_state |= IS_ACTIVE;
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trace_rip("Recv", "from", from, ifp, rip, size);
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if (rip->rip_vers == 0) {
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if (from->sin_addr.s_addr != bad_router)
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msglog("RIP version 0, cmd %d, packet received"
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" from %s",
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rip->rip_cmd, naddr_ntoa(FROM_NADDR));
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bad_router = from->sin_addr.s_addr;
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return;
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}
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if (size > MAXPACKETSIZE) {
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if (from->sin_addr.s_addr != bad_router)
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msglog("packet at least %d bytes too long received"
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" from %s",
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size-MAXPACKETSIZE, naddr_ntoa(FROM_NADDR));
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bad_router = from->sin_addr.s_addr;
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return;
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}
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n = rip->rip_nets;
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lim = (struct netinfo *)((char*)rip + size);
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/* Notice authentication.
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* As required by section 4.2 in RFC 1723, discard authenticated
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* RIPv2 messages, but only if configured for that silliness.
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*
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* RIPv2 authentication is lame, since snooping on the wire makes
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* its simple passwords evident. Also, why authenticate queries?
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* Why should a RIPv2 implementation with authentication disabled
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* not be able to listen to RIPv2 packets with authenication, while
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* RIPv1 systems will listen? Crazy!
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*/
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if (!auth_ok
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&& rip->rip_vers >= RIPv2
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&& n < lim && n->n_family == RIP_AF_AUTH) {
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if (from->sin_addr.s_addr != use_auth)
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msglog("RIPv2 message with authentication"
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" from %s discarded",
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naddr_ntoa(FROM_NADDR));
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use_auth = from->sin_addr.s_addr;
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trace_pkt("discard authenticated RIPv2 message\n");
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return;
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}
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switch (rip->rip_cmd) {
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case RIPCMD_REQUEST:
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/* did the request come from a router?
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*/
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if (from->sin_port == htons(RIP_PORT)) {
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/* yes, ignore it if RIP is off so that it does not
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* depend on us.
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*/
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if (rip_sock < 0) {
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trace_pkt("ignore request while RIP off\n");
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return;
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}
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/* Ignore the request if we talking to ourself
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* (and not a remote gateway).
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*/
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if (ifwithaddr(FROM_NADDR, 0, 0) != 0) {
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trace_pkt("discard our own RIP request\n");
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return;
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}
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}
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/* According to RFC 1723, we should ignore unathenticated
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* queries. That is too silly to bother with. Sheesh!
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* Are forwarding tables supposed to be secret? When
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* a bad guy can infer them with test traffic?
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* Maybe on firewalls you'd care, but not enough to
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* give up the diagnostic facilities of remote probing.
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*/
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if (n >= lim
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|| size%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
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if (from->sin_addr.s_addr != bad_len)
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msglog("request of bad length (%d) from %s",
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size, naddr_ntoa(FROM_NADDR));
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bad_len = from->sin_addr.s_addr;
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}
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for (; n < lim; n++) {
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n->n_metric = ntohl(n->n_metric);
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/* A single entry with family RIP_AF_UNSPEC and
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* metric HOPCNT_INFINITY means "all routes".
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* We respond to routers only if we are acting
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* as a supplier, or to anyone other than a router
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* (i.e. a query).
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*
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* Answer a query from a stray program with all
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* we know. Filter the answer to a query from a
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* router in the about same way broadcasts are
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* filtered.
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*
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* Only answer a router if we are a supplier
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* to keep an unwary host that is just starting
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* from picking us an a router.
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*/
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if (n->n_family == RIP_AF_UNSPEC
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&& n->n_metric == HOPCNT_INFINITY
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&& n == rip->rip_nets
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&& n+1 == lim) {
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if (from->sin_port != htons(RIP_PORT)) {
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/* query from `rtquery` or similar
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*/
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supply(from, ifp,
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OUT_QUERY, 0, rip->rip_vers);
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} else if (supplier) {
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/* a router trying to prime its
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* tables.
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*/
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supply(from, ifp,
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OUT_UNICAST, 0, rip->rip_vers);
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}
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return;
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}
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if (n->n_family != RIP_AF_INET) {
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if (from->sin_addr.s_addr != bad_router)
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msglog("request from %s"
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" for unsupported (af %d) %s",
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naddr_ntoa(FROM_NADDR),
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ntohs(n->n_family),
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naddr_ntoa(n->n_dst));
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bad_router = from->sin_addr.s_addr;
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return;
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}
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dst = n->n_dst;
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if (!check_dst(dst)) {
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if (from->sin_addr.s_addr != bad_router)
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msglog("bad queried destination"
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" %s from %s",
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naddr_ntoa(dst),
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naddr_ntoa(FROM_NADDR));
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bad_router = from->sin_addr.s_addr;
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return;
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}
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if (rip->rip_vers == RIPv1
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|| 0 == (mask = ntohl(n->n_mask))
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|| 0 != (ntohl(dst) & ~mask))
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mask = ripv1_mask_host(dst,ifp);
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rt = rtget(dst, mask);
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if (!rt && dst != RIP_DEFAULT)
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rt = rtfind(n->n_dst);
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n->n_tag = 0;
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n->n_nhop = 0;
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if (rip->rip_vers == RIPv1) {
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n->n_mask = 0;
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} else {
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n->n_mask = mask;
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}
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if (rt == 0) {
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n->n_metric = HOPCNT_INFINITY;
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} else {
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n->n_metric = rt->rt_metric+1;
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n->n_metric += (ifp!=0) ? ifp->int_metric : 1;
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if (n->n_metric > HOPCNT_INFINITY)
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n->n_metric = HOPCNT_INFINITY;
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if (rip->rip_vers != RIPv1) {
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n->n_tag = rt->rt_tag;
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if (ifp != 0
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&& on_net(rt->rt_gate,
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ifp->int_net,
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ifp->int_mask)
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&& rt->rt_gate != ifp->int_addr)
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n->n_nhop = rt->rt_gate;
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}
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}
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HTONL(n->n_metric);
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}
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/* Answer about specific routes.
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* Only answer a router if we are a supplier
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* to keep an unwary host that is just starting
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* from picking us an a router.
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*/
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rip->rip_cmd = RIPCMD_RESPONSE;
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rip->rip_res1 = 0;
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if (rip->rip_vers != RIPv1)
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rip->rip_vers = RIPv2;
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if (from->sin_port != htons(RIP_PORT)) {
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/* query */
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(void)output(OUT_QUERY, from, ifp, rip, size);
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} else if (supplier) {
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(void)output(OUT_UNICAST, from, ifp, rip, size);
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}
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return;
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case RIPCMD_TRACEON:
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case RIPCMD_TRACEOFF:
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/* verify message came from a privileged port */
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if (ntohs(from->sin_port) > IPPORT_RESERVED) {
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msglog("trace command from untrusted port on %s",
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naddr_ntoa(FROM_NADDR));
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return;
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}
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if (ifp == 0) {
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msglog("trace command from unknown router %s",
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naddr_ntoa(FROM_NADDR));
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return;
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}
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if (rip->rip_cmd == RIPCMD_TRACEON) {
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rip->rip_tracefile[size-4] = '\0';
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trace_on((char*)rip->rip_tracefile, 0);
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} else {
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trace_off("tracing turned off by %s\n",
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naddr_ntoa(FROM_NADDR));
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}
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return;
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case RIPCMD_RESPONSE:
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if (size%sizeof(*n) != sizeof(struct rip)%sizeof(*n)) {
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if (from->sin_addr.s_addr != bad_len)
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msglog("response of bad length (%d) from %s",
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size, naddr_ntoa(FROM_NADDR));
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bad_len = from->sin_addr.s_addr;
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}
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/* verify message came from a router */
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if (from->sin_port != ntohs(RIP_PORT)) {
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trace_pkt("discard RIP response from unknown port\n");
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return;
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}
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if (rip_sock < 0) {
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trace_pkt("discard response while RIP off\n");
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return;
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}
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/* Are we talking to ourself or a remote gateway?
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*/
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ifp1 = ifwithaddr(FROM_NADDR, 0, 1);
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if (ifp1) {
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if (ifp1->int_state & IS_REMOTE) {
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if (ifp1->int_state & IS_PASSIVE) {
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msglog("bogus input from %s on"
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" supposedly passive %s",
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naddr_ntoa(FROM_NADDR),
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ifp1->int_name);
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} else {
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ifp1->int_act_time = now.tv_sec;
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if (if_ok(ifp1, "remote "))
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addrouteforif(ifp1);
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}
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} else {
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trace_pkt("discard our own RIP response\n");
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}
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return;
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}
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/* Check the router from which message originated. We accept
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* routing packets from routers directly connected via
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* broadcast or point-to-point networks, and from
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* those listed in /etc/gateways.
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*/
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if (!ifp) {
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if (from->sin_addr.s_addr != unk_router)
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msglog("packet from unknown router %s"
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" or via unidentified interface",
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naddr_ntoa(FROM_NADDR));
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unk_router = from->sin_addr.s_addr;
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return;
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}
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if (ifp->int_state & IS_PASSIVE) {
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trace_act("packet from %s via passive interface %s\n",
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naddr_ntoa(FROM_NADDR),
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ifp->int_name);
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return;
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}
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/* Check required version
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*/
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if (((ifp->int_state & IS_NO_RIPV1_IN)
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&& rip->rip_vers == RIPv1)
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|| ((ifp->int_state & IS_NO_RIPV2_IN)
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&& rip->rip_vers != RIPv1)) {
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trace_pkt("discard RIPv%d response\n",
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rip->rip_vers);
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return;
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}
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/* Ignore routes via dead interface.
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*/
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if (ifp->int_state & IS_BROKE) {
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trace_pkt("discard response via broken interface %s\n",
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ifp->int_name);
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return;
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}
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/* Authenticate the packet if we have a secret.
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*/
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if (ifp->int_passwd[0] != '\0') {
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if (n >= lim
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|| n->n_family != RIP_AF_AUTH
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|| ((struct netauth*)n)->a_type != RIP_AUTH_PW) {
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if (from->sin_addr.s_addr != use_auth)
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msglog("missing password from %s",
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naddr_ntoa(FROM_NADDR));
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use_auth = from->sin_addr.s_addr;
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return;
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} else if (0 != bcmp(((struct netauth*)n)->au.au_pw,
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ifp->int_passwd,
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sizeof(ifp->int_passwd))) {
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if (from->sin_addr.s_addr != use_auth)
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msglog("bad password from %s",
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naddr_ntoa(FROM_NADDR));
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use_auth = from->sin_addr.s_addr;
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return;
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}
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}
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for (; n < lim; n++) {
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if (n->n_family == RIP_AF_AUTH)
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continue;
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NTOHL(n->n_metric);
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dst = n->n_dst;
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if (n->n_family != RIP_AF_INET
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&& (n->n_family != RIP_AF_UNSPEC
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|| dst != RIP_DEFAULT)) {
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if (from->sin_addr.s_addr != bad_router)
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msglog("route from %s to unsupported"
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" address family %d,"
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" destination %s",
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naddr_ntoa(FROM_NADDR),
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n->n_family,
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naddr_ntoa(dst));
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bad_router = from->sin_addr.s_addr;
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continue;
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}
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if (!check_dst(dst)) {
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if (from->sin_addr.s_addr != bad_router)
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msglog("bad destination %s from %s",
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naddr_ntoa(dst),
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naddr_ntoa(FROM_NADDR));
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bad_router = from->sin_addr.s_addr;
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return;
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}
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if (n->n_metric == 0
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|| n->n_metric > HOPCNT_INFINITY) {
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if (from->sin_addr.s_addr != bad_router)
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msglog("bad metric %d from %s"
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" for destination %s",
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n->n_metric,
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naddr_ntoa(FROM_NADDR),
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naddr_ntoa(dst));
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bad_router = from->sin_addr.s_addr;
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return;
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}
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/* Notice the next-hop.
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*/
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gate = from->sin_addr.s_addr;
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if (n->n_nhop != 0
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&& rip->rip_vers == RIPv2) {
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/* Ignore the route if it points to us */
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if (0 != ifwithaddr(n->n_nhop, 1, 0))
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continue;
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/* Use it only if it is valid. */
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if (on_net(n->n_nhop,
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ifp->int_net, ifp->int_mask)
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&& check_dst(n->n_nhop)) {
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gate = n->n_nhop;
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} else {
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if (bad_nhop != from->sin_addr.s_addr)
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msglog("router %s to %s has"
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" bad next hop %s",
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naddr_ntoa(FROM_NADDR),
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naddr_ntoa(dst),
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naddr_ntoa(n->n_nhop));
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bad_nhop = from->sin_addr.s_addr;
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}
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}
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if (rip->rip_vers == RIPv1
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|| 0 == (mask = ntohl(n->n_mask))) {
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mask = ripv1_mask_host(dst,ifp);
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} else if ((ntohl(dst) & ~mask) != 0) {
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if (bad_mask != from->sin_addr.s_addr) {
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msglog("router %s sent bad netmask"
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" %#x with %s",
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naddr_ntoa(FROM_NADDR),
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mask,
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naddr_ntoa(dst));
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bad_mask = from->sin_addr.s_addr;
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}
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continue;
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}
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if (rip->rip_vers == RIPv1)
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n->n_tag = 0;
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|
|
/* Adjust metric according to incoming interface..
|
|
*/
|
|
n->n_metric += ifp->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 (ifp->int_d_metric != 0
|
|
&& dst == RIP_DEFAULT
|
|
&& n->n_metric >= ifp->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(ifp, 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;
|
|
|
|
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 faking the
|
|
* RIPv1 route with a metric that reflects the most
|
|
* distant part of the subnet. Also never
|
|
* aggregate 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.
|
|
*/
|
|
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);
|
|
}
|