2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
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13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
35 #include "opt_ipsec.h"
38 #include <sys/param.h>
39 #include <sys/systm.h>
41 #include <sys/protosw.h>
42 #include <sys/socket.h>
44 #include <sys/kernel.h>
45 #include <sys/sysctl.h>
48 #include <net/if_types.h>
49 #include <net/route.h>
51 #include <netinet/in.h>
52 #include <netinet/in_pcb.h>
53 #include <netinet/in_systm.h>
54 #include <netinet/in_var.h>
55 #include <netinet/ip.h>
56 #include <netinet/ip_icmp.h>
57 #include <netinet/ip_var.h>
58 #include <netinet/ip_options.h>
59 #include <netinet/tcp.h>
60 #include <netinet/tcp_var.h>
61 #include <netinet/tcpip.h>
62 #include <netinet/icmp_var.h>
65 #include <netipsec/ipsec.h>
66 #include <netipsec/key.h>
69 #include <machine/in_cksum.h>
71 #include <security/mac/mac_framework.h>
74 * ICMP routines: error generation, receive packet processing, and
75 * routines to turnaround packets back to the originator, and
76 * host table maintenance routines.
79 struct icmpstat icmpstat;
80 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
81 &icmpstat, icmpstat, "");
83 static int icmpmaskrepl = 0;
84 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
85 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets.");
87 static u_int icmpmaskfake = 0;
88 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
89 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets.");
91 static int drop_redirect = 0;
92 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
93 &drop_redirect, 0, "Ignore ICMP redirects");
95 static int log_redirect = 0;
96 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
97 &log_redirect, 0, "Log ICMP redirects to the console");
99 static int icmplim = 200;
100 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
101 &icmplim, 0, "Maximum number of ICMP responses per second");
103 static int icmplim_output = 1;
104 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
105 &icmplim_output, 0, "Enable rate limiting of ICMP responses");
107 static char reply_src[IFNAMSIZ];
108 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
109 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets.");
111 static int icmp_rfi = 0;
112 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
113 &icmp_rfi, 0, "ICMP reply from incoming interface for "
114 "non-local packets");
116 static int icmp_quotelen = 8;
117 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
118 &icmp_quotelen, 0, "Number of bytes from original packet to "
119 "quote in ICMP reply");
122 * ICMP broadcast echo sysctl
125 static int icmpbmcastecho = 0;
126 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
127 &icmpbmcastecho, 0, "");
134 static void icmp_reflect(struct mbuf *);
135 static void icmp_send(struct mbuf *, struct mbuf *);
137 extern struct protosw inetsw[];
140 * Generate an error packet of type error
141 * in response to bad packet ip.
144 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
146 register struct ip *oip = mtod(n, struct ip *), *nip;
147 register unsigned oiphlen = oip->ip_hl << 2;
148 register struct icmp *icp;
149 register struct mbuf *m;
150 unsigned icmplen, icmpelen, nlen;
152 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
155 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
157 if (type != ICMP_REDIRECT)
158 icmpstat.icps_error++;
161 * if the original packet was encrypted.
162 * if not the first fragment of message.
163 * in response to a multicast or broadcast packet.
164 * if the old packet protocol was an ICMP error message.
166 if (n->m_flags & M_DECRYPTED)
168 if (oip->ip_off & ~(IP_MF|IP_DF))
170 if (n->m_flags & (M_BCAST|M_MCAST))
172 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
173 n->m_len >= oiphlen + ICMP_MINLEN &&
174 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
175 icmpstat.icps_oldicmp++;
178 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
179 if (oiphlen + 8 > n->m_len)
182 * Calculate length to quote from original packet and
183 * prevent the ICMP mbuf from overflowing.
184 * Unfortunatly this is non-trivial since ip_forward()
185 * sends us truncated packets.
187 nlen = m_length(n, NULL);
188 if (oip->ip_p == IPPROTO_TCP) {
192 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
195 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
196 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
198 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
199 tcphlen = th->th_off << 2;
200 if (tcphlen < sizeof(struct tcphdr))
202 if (oip->ip_len < oiphlen + tcphlen)
204 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
206 if (n->m_len < oiphlen + tcphlen &&
207 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
209 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen));
211 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen));
213 icmplen = min(oiphlen + icmpelen, nlen);
214 if (icmplen < sizeof(struct ip))
217 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
218 m = m_gethdr(M_DONTWAIT, MT_DATA);
220 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
224 mac_create_mbuf_netlayer(n, m);
226 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
227 m_align(m, ICMP_MINLEN + icmplen);
228 m->m_len = ICMP_MINLEN + icmplen;
230 /* XXX MRT make the outgoing packet use the same FIB
231 * that was associated with the incoming packet
233 M_SETFIB(m, M_GETFIB(n));
234 icp = mtod(m, struct icmp *);
235 icmpstat.icps_outhist[type]++;
236 icp->icmp_type = type;
237 if (type == ICMP_REDIRECT)
238 icp->icmp_gwaddr.s_addr = dest;
242 * The following assignments assume an overlay with the
243 * just zeroed icmp_void field.
245 if (type == ICMP_PARAMPROB) {
246 icp->icmp_pptr = code;
248 } else if (type == ICMP_UNREACH &&
249 code == ICMP_UNREACH_NEEDFRAG && mtu) {
250 icp->icmp_nextmtu = htons(mtu);
253 icp->icmp_code = code;
256 * Copy the quotation into ICMP message and
257 * convert quoted IP header back to network representation.
259 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
261 nip->ip_len = htons(nip->ip_len);
262 nip->ip_off = htons(nip->ip_off);
265 * Set up ICMP message mbuf and copy old IP header (without options
266 * in front of ICMP message.
267 * If the original mbuf was meant to bypass the firewall, the error
268 * reply should bypass as well.
270 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
271 m->m_data -= sizeof(struct ip);
272 m->m_len += sizeof(struct ip);
273 m->m_pkthdr.len = m->m_len;
274 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
275 nip = mtod(m, struct ip *);
276 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
277 nip->ip_len = m->m_len;
278 nip->ip_v = IPVERSION;
280 nip->ip_p = IPPROTO_ICMP;
289 * Process a received ICMP message.
292 icmp_input(struct mbuf *m, int off)
295 struct in_ifaddr *ia;
296 struct ip *ip = mtod(m, struct ip *);
297 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
299 int icmplen = ip->ip_len;
301 void (*ctlfunc)(int, struct sockaddr *, void *);
305 * Locate icmp structure in mbuf, and check
306 * that not corrupted and of at least minimum length.
310 char buf[4 * sizeof "123"];
311 strcpy(buf, inet_ntoa(ip->ip_src));
312 printf("icmp_input from %s to %s, len %d\n",
313 buf, inet_ntoa(ip->ip_dst), icmplen);
316 if (icmplen < ICMP_MINLEN) {
317 icmpstat.icps_tooshort++;
320 i = hlen + min(icmplen, ICMP_ADVLENMIN);
321 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
322 icmpstat.icps_tooshort++;
325 ip = mtod(m, struct ip *);
328 icp = mtod(m, struct icmp *);
329 if (in_cksum(m, icmplen)) {
330 icmpstat.icps_checksum++;
336 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
338 * Deliver very specific ICMP type only.
340 switch (icp->icmp_type) {
351 printf("icmp_input, type %d code %d\n", icp->icmp_type,
356 * Message type specific processing.
358 if (icp->icmp_type > ICMP_MAXTYPE)
362 bzero(&icmpsrc, sizeof(icmpsrc));
363 icmpsrc.sin_len = sizeof(struct sockaddr_in);
364 icmpsrc.sin_family = AF_INET;
365 bzero(&icmpdst, sizeof(icmpdst));
366 icmpdst.sin_len = sizeof(struct sockaddr_in);
367 icmpdst.sin_family = AF_INET;
368 bzero(&icmpgw, sizeof(icmpgw));
369 icmpgw.sin_len = sizeof(struct sockaddr_in);
370 icmpgw.sin_family = AF_INET;
372 icmpstat.icps_inhist[icp->icmp_type]++;
373 code = icp->icmp_code;
374 switch (icp->icmp_type) {
378 case ICMP_UNREACH_NET:
379 case ICMP_UNREACH_HOST:
380 case ICMP_UNREACH_SRCFAIL:
381 case ICMP_UNREACH_NET_UNKNOWN:
382 case ICMP_UNREACH_HOST_UNKNOWN:
383 case ICMP_UNREACH_ISOLATED:
384 case ICMP_UNREACH_TOSNET:
385 case ICMP_UNREACH_TOSHOST:
386 case ICMP_UNREACH_HOST_PRECEDENCE:
387 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
388 code = PRC_UNREACH_NET;
391 case ICMP_UNREACH_NEEDFRAG:
396 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
397 * Treat subcodes 2,3 as immediate RST
399 case ICMP_UNREACH_PROTOCOL:
400 case ICMP_UNREACH_PORT:
401 code = PRC_UNREACH_PORT;
404 case ICMP_UNREACH_NET_PROHIB:
405 case ICMP_UNREACH_HOST_PROHIB:
406 case ICMP_UNREACH_FILTER_PROHIB:
407 code = PRC_UNREACH_ADMIN_PROHIB;
418 code += PRC_TIMXCEED_INTRANS;
424 code = PRC_PARAMPROB;
427 case ICMP_SOURCEQUENCH:
433 * Problem with datagram; advise higher level routines.
435 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
436 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
437 icmpstat.icps_badlen++;
440 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
441 /* Discard ICMP's in response to multicast packets */
442 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
446 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
448 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
450 * XXX if the packet contains [IPv4 AH TCP], we can't make a
451 * notification to TCP layer.
453 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
455 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
456 (void *)&icp->icmp_ip);
460 icmpstat.icps_badcode++;
465 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
466 icmpstat.icps_bmcastecho++;
469 icp->icmp_type = ICMP_ECHOREPLY;
470 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
477 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
478 icmpstat.icps_bmcasttstamp++;
481 if (icmplen < ICMP_TSLEN) {
482 icmpstat.icps_badlen++;
485 icp->icmp_type = ICMP_TSTAMPREPLY;
486 icp->icmp_rtime = iptime();
487 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
488 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
494 if (icmpmaskrepl == 0)
497 * We are not able to respond with all ones broadcast
498 * unless we receive it over a point-to-point interface.
500 if (icmplen < ICMP_MASKLEN)
502 switch (ip->ip_dst.s_addr) {
504 case INADDR_BROADCAST:
506 icmpdst.sin_addr = ip->ip_src;
510 icmpdst.sin_addr = ip->ip_dst;
512 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
513 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
518 icp->icmp_type = ICMP_MASKREPLY;
519 if (icmpmaskfake == 0)
520 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
522 icp->icmp_mask = icmpmaskfake;
523 if (ip->ip_src.s_addr == 0) {
524 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
525 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
526 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
527 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
530 ip->ip_len += hlen; /* since ip_input deducts this */
531 icmpstat.icps_reflect++;
532 icmpstat.icps_outhist[icp->icmp_type]++;
540 src = ntohl(ip->ip_src.s_addr);
541 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
542 gw = ntohl(icp->icmp_gwaddr.s_addr);
543 printf("icmp redirect from %d.%d.%d.%d: "
544 "%d.%d.%d.%d => %d.%d.%d.%d\n",
545 (int)(src >> 24), (int)((src >> 16) & 0xff),
546 (int)((src >> 8) & 0xff), (int)(src & 0xff),
547 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
548 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
549 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
550 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
553 * RFC1812 says we must ignore ICMP redirects if we
554 * are acting as router.
556 if (drop_redirect || ipforwarding)
560 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
561 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
562 icmpstat.icps_badlen++;
566 * Short circuit routing redirects to force
567 * immediate change in the kernel's routing
568 * tables. The message is also handed to anyone
569 * listening on a raw socket (e.g. the routing
570 * daemon for use in updating its tables).
572 icmpgw.sin_addr = ip->ip_src;
573 icmpdst.sin_addr = icp->icmp_gwaddr;
576 char buf[4 * sizeof "123"];
577 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
579 printf("redirect dst %s to %s\n",
580 buf, inet_ntoa(icp->icmp_gwaddr));
583 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
584 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
585 in_rtredirect((struct sockaddr *)&icmpsrc,
586 (struct sockaddr *)&icmpdst,
587 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
588 (struct sockaddr *)&icmpgw, fibnum);
590 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
592 key_sa_routechange((struct sockaddr *)&icmpsrc);
597 * No kernel processing for the following;
598 * just fall through to send to raw listener.
601 case ICMP_ROUTERADVERT:
602 case ICMP_ROUTERSOLICIT:
603 case ICMP_TSTAMPREPLY:
619 * Reflect the ip packet back to the source
622 icmp_reflect(struct mbuf *m)
624 struct ip *ip = mtod(m, struct ip *);
627 struct in_ifaddr *ia;
629 struct mbuf *opts = 0;
630 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
632 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
633 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
634 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
635 m_freem(m); /* Bad return address */
636 icmpstat.icps_badaddr++;
637 goto done; /* Ip_output() will check for broadcast */
641 ip->ip_dst = ip->ip_src;
644 * Source selection for ICMP replies:
646 * If the incoming packet was addressed directly to one of our
647 * own addresses, use dst as the src for the reply.
649 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
650 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
653 * If the incoming packet was addressed to one of our broadcast
654 * addresses, use the first non-broadcast address which corresponds
655 * to the incoming interface.
657 if (m->m_pkthdr.rcvif != NULL &&
658 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
659 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
660 if (ifa->ifa_addr->sa_family != AF_INET)
663 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
669 * If the packet was transiting through us, use the address of
670 * the interface the packet came through in. If that interface
671 * doesn't have a suitable IP address, the normal selection
674 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) {
675 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
676 if (ifa->ifa_addr->sa_family != AF_INET)
683 * If the incoming packet was not addressed directly to us, use
684 * designated interface for icmp replies specified by sysctl
685 * net.inet.icmp.reply_src (default not set). Otherwise continue
686 * with normal source selection.
688 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) {
689 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) {
690 if (ifa->ifa_addr->sa_family != AF_INET)
697 * If the packet was transiting through us, use the address of
698 * the interface that is the closest to the packet source.
699 * When we don't have a route back to the packet source, stop here
700 * and drop the packet.
702 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
705 icmpstat.icps_noroute++;
710 mac_reflect_mbuf_icmp(m);
712 t = IA_SIN(ia)->sin_addr;
714 ip->ip_ttl = ip_defttl;
722 * Retrieve any source routing from the incoming packet;
723 * add on any record-route or timestamp options.
725 cp = (u_char *) (ip + 1);
726 if ((opts = ip_srcroute(m)) == 0 &&
727 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
728 opts->m_len = sizeof(struct in_addr);
729 mtod(opts, struct in_addr *)->s_addr = 0;
734 printf("icmp_reflect optlen %d rt %d => ",
735 optlen, opts->m_len);
737 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
738 opt = cp[IPOPT_OPTVAL];
739 if (opt == IPOPT_EOL)
741 if (opt == IPOPT_NOP)
744 if (cnt < IPOPT_OLEN + sizeof(*cp))
746 len = cp[IPOPT_OLEN];
747 if (len < IPOPT_OLEN + sizeof(*cp) ||
752 * Should check for overflow, but it "can't happen"
754 if (opt == IPOPT_RR || opt == IPOPT_TS ||
755 opt == IPOPT_SECURITY) {
757 mtod(opts, caddr_t) + opts->m_len, len);
761 /* Terminate & pad, if necessary */
762 cnt = opts->m_len % 4;
764 for (; cnt < 4; cnt++) {
765 *(mtod(opts, caddr_t) + opts->m_len) =
772 printf("%d\n", opts->m_len);
776 * Now strip out original options by copying rest of first
777 * mbuf's data back, and adjust the IP length.
779 ip->ip_len -= optlen;
780 ip->ip_v = IPVERSION;
783 if (m->m_flags & M_PKTHDR)
784 m->m_pkthdr.len -= optlen;
785 optlen += sizeof(struct ip);
786 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
787 (unsigned)(m->m_len - sizeof(struct ip)));
789 m_tag_delete_nonpersistent(m);
790 m->m_flags &= ~(M_BCAST|M_MCAST);
798 * Send an icmp packet back to the ip level,
799 * after supplying a checksum.
802 icmp_send(struct mbuf *m, struct mbuf *opts)
804 register struct ip *ip = mtod(m, struct ip *);
806 register struct icmp *icp;
808 hlen = ip->ip_hl << 2;
811 icp = mtod(m, struct icmp *);
813 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
816 m->m_pkthdr.rcvif = (struct ifnet *)0;
819 char buf[4 * sizeof "123"];
820 strcpy(buf, inet_ntoa(ip->ip_dst));
821 printf("icmp_send dst %s src %s\n",
822 buf, inet_ntoa(ip->ip_src));
825 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
829 * Return milliseconds since 00:00 GMT in network format.
838 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
843 * Return the next larger or smaller MTU plateau (table from RFC 1191)
844 * given current value MTU. If DIR is less than zero, a larger plateau
845 * is returned; otherwise, a smaller value is returned.
848 ip_next_mtu(int mtu, int dir)
850 static int mtutab[] = {
851 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
856 size = (sizeof mtutab) / (sizeof mtutab[0]);
858 for (i = 0; i < size; i++)
862 for (i = size - 1; i >= 0; i--)
865 if (mtu == mtutab[0])
873 * badport_bandlim() - check for ICMP bandwidth limit
875 * Return 0 if it is ok to send an ICMP error response, -1 if we have
876 * hit our bandwidth limit and it is not ok.
878 * If icmplim is <= 0, the feature is disabled and 0 is returned.
880 * For now we separate the TCP and UDP subsystems w/ different 'which'
881 * values. We may eventually remove this separation (and simplify the
884 * Note that the printing of the error message is delayed so we can
885 * properly print the icmp error rate that the system was trying to do
886 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
887 * the 'final' error, but it doesn't make sense to solve the printing
888 * delay with more complex code.
892 badport_bandlim(int which)
894 #define N(a) (sizeof (a) / sizeof (a[0]))
897 struct timeval lasttime;
899 } rates[BANDLIM_MAX+1] = {
900 { "icmp unreach response" },
901 { "icmp ping response" },
902 { "icmp tstamp response" },
903 { "closed port RST response" },
904 { "open port RST response" },
905 { "icmp6 unreach response" }
909 * Return ok status if feature disabled or argument out of range.
911 if (icmplim > 0 && (u_int) which < N(rates)) {
912 struct rate *r = &rates[which];
913 int opps = r->curpps;
915 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim))
916 return -1; /* discard packet */
918 * If we've dropped below the threshold after having
919 * rate-limited traffic print the message. This preserves
920 * the previous behaviour at the expense of added complexity.
922 if (icmplim_output && opps > icmplim)
923 printf("Limiting %s from %d to %d packets/sec\n",
924 r->type, opps, icmplim);
926 return 0; /* okay to send packet */