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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12 * documentation and/or other materials provided with the distribution.
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>
46 #include <sys/vimage.h>
49 #include <net/if_types.h>
50 #include <net/route.h>
52 #include <netinet/in.h>
53 #include <netinet/in_pcb.h>
54 #include <netinet/in_systm.h>
55 #include <netinet/in_var.h>
56 #include <netinet/ip.h>
57 #include <netinet/ip_icmp.h>
58 #include <netinet/ip_var.h>
59 #include <netinet/ip_options.h>
60 #include <netinet/tcp.h>
61 #include <netinet/tcp_var.h>
62 #include <netinet/tcpip.h>
63 #include <netinet/icmp_var.h>
66 #include <netipsec/ipsec.h>
67 #include <netipsec/key.h>
70 #include <machine/in_cksum.h>
72 #include <security/mac/mac_framework.h>
75 * ICMP routines: error generation, receive packet processing, and
76 * routines to turnaround packets back to the originator, and
77 * host table maintenance routines.
80 struct icmpstat icmpstat;
81 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
82 &icmpstat, icmpstat, "");
84 static int icmpmaskrepl = 0;
85 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
86 &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets.");
88 static u_int icmpmaskfake = 0;
89 SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
90 &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets.");
92 static int drop_redirect = 0;
93 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
94 &drop_redirect, 0, "Ignore ICMP redirects");
96 static int log_redirect = 0;
97 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
98 &log_redirect, 0, "Log ICMP redirects to the console");
100 static int icmplim = 200;
101 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
102 &icmplim, 0, "Maximum number of ICMP responses per second");
104 static int icmplim_output = 1;
105 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
106 &icmplim_output, 0, "Enable rate limiting of ICMP responses");
108 static char reply_src[IFNAMSIZ];
109 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
110 &reply_src, IFNAMSIZ, "icmp reply source for non-local packets.");
112 static int icmp_rfi = 0;
113 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
114 &icmp_rfi, 0, "ICMP reply from incoming interface for "
115 "non-local packets");
117 static int icmp_quotelen = 8;
118 SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
119 &icmp_quotelen, 0, "Number of bytes from original packet to "
120 "quote in ICMP reply");
123 * ICMP broadcast echo sysctl
126 static int icmpbmcastecho = 0;
127 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
128 &icmpbmcastecho, 0, "");
135 static void icmp_reflect(struct mbuf *);
136 static void icmp_send(struct mbuf *, struct mbuf *);
138 extern struct protosw inetsw[];
141 * Generate an error packet of type error
142 * in response to bad packet ip.
145 icmp_error(struct mbuf *n, int type, int code, n_long dest, int mtu)
147 register struct ip *oip = mtod(n, struct ip *), *nip;
148 register unsigned oiphlen = oip->ip_hl << 2;
149 register struct icmp *icp;
150 register struct mbuf *m;
151 unsigned icmplen, icmpelen, nlen;
153 KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
156 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
158 if (type != ICMP_REDIRECT)
159 V_icmpstat.icps_error++;
162 * if the original packet was encrypted.
163 * if not the first fragment of message.
164 * in response to a multicast or broadcast packet.
165 * if the old packet protocol was an ICMP error message.
167 if (n->m_flags & M_DECRYPTED)
169 if (oip->ip_off & ~(IP_MF|IP_DF))
171 if (n->m_flags & (M_BCAST|M_MCAST))
173 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
174 n->m_len >= oiphlen + ICMP_MINLEN &&
175 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
176 V_icmpstat.icps_oldicmp++;
179 /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
180 if (oiphlen + 8 > n->m_len)
183 * Calculate length to quote from original packet and
184 * prevent the ICMP mbuf from overflowing.
185 * Unfortunatly this is non-trivial since ip_forward()
186 * sends us truncated packets.
188 nlen = m_length(n, NULL);
189 if (oip->ip_p == IPPROTO_TCP) {
193 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
196 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
197 ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
199 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
200 tcphlen = th->th_off << 2;
201 if (tcphlen < sizeof(struct tcphdr))
203 if (oip->ip_len < oiphlen + tcphlen)
205 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
207 if (n->m_len < oiphlen + tcphlen &&
208 ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
210 icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen));
212 stdreply: icmpelen = max(8, min(icmp_quotelen, oip->ip_len - oiphlen));
214 icmplen = min(oiphlen + icmpelen, nlen);
215 if (icmplen < sizeof(struct ip))
218 if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
219 m = m_gethdr(M_DONTWAIT, MT_DATA);
221 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
225 mac_netinet_icmp_reply(n, m);
227 icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
228 m_align(m, ICMP_MINLEN + icmplen);
229 m->m_len = ICMP_MINLEN + icmplen;
231 /* XXX MRT make the outgoing packet use the same FIB
232 * that was associated with the incoming packet
234 M_SETFIB(m, M_GETFIB(n));
235 icp = mtod(m, struct icmp *);
236 V_icmpstat.icps_outhist[type]++;
237 icp->icmp_type = type;
238 if (type == ICMP_REDIRECT)
239 icp->icmp_gwaddr.s_addr = dest;
243 * The following assignments assume an overlay with the
244 * just zeroed icmp_void field.
246 if (type == ICMP_PARAMPROB) {
247 icp->icmp_pptr = code;
249 } else if (type == ICMP_UNREACH &&
250 code == ICMP_UNREACH_NEEDFRAG && mtu) {
251 icp->icmp_nextmtu = htons(mtu);
254 icp->icmp_code = code;
257 * Copy the quotation into ICMP message and
258 * convert quoted IP header back to network representation.
260 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
262 nip->ip_len = htons(nip->ip_len);
263 nip->ip_off = htons(nip->ip_off);
266 * Set up ICMP message mbuf and copy old IP header (without options
267 * in front of ICMP message.
268 * If the original mbuf was meant to bypass the firewall, the error
269 * reply should bypass as well.
271 m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
272 m->m_data -= sizeof(struct ip);
273 m->m_len += sizeof(struct ip);
274 m->m_pkthdr.len = m->m_len;
275 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
276 nip = mtod(m, struct ip *);
277 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
278 nip->ip_len = m->m_len;
279 nip->ip_v = IPVERSION;
281 nip->ip_p = IPPROTO_ICMP;
290 * Process a received ICMP message.
293 icmp_input(struct mbuf *m, int off)
296 struct in_ifaddr *ia;
297 struct ip *ip = mtod(m, struct ip *);
298 struct sockaddr_in icmpsrc, icmpdst, icmpgw;
300 int icmplen = ip->ip_len;
302 void (*ctlfunc)(int, struct sockaddr *, void *);
306 * Locate icmp structure in mbuf, and check
307 * that not corrupted and of at least minimum length.
311 char buf[4 * sizeof "123"];
312 strcpy(buf, inet_ntoa(ip->ip_src));
313 printf("icmp_input from %s to %s, len %d\n",
314 buf, inet_ntoa(ip->ip_dst), icmplen);
317 if (icmplen < ICMP_MINLEN) {
318 V_icmpstat.icps_tooshort++;
321 i = hlen + min(icmplen, ICMP_ADVLENMIN);
322 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
323 V_icmpstat.icps_tooshort++;
326 ip = mtod(m, struct ip *);
329 icp = mtod(m, struct icmp *);
330 if (in_cksum(m, icmplen)) {
331 V_icmpstat.icps_checksum++;
337 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
339 * Deliver very specific ICMP type only.
341 switch (icp->icmp_type) {
352 printf("icmp_input, type %d code %d\n", icp->icmp_type,
357 * Message type specific processing.
359 if (icp->icmp_type > ICMP_MAXTYPE)
363 bzero(&icmpsrc, sizeof(icmpsrc));
364 icmpsrc.sin_len = sizeof(struct sockaddr_in);
365 icmpsrc.sin_family = AF_INET;
366 bzero(&icmpdst, sizeof(icmpdst));
367 icmpdst.sin_len = sizeof(struct sockaddr_in);
368 icmpdst.sin_family = AF_INET;
369 bzero(&icmpgw, sizeof(icmpgw));
370 icmpgw.sin_len = sizeof(struct sockaddr_in);
371 icmpgw.sin_family = AF_INET;
373 V_icmpstat.icps_inhist[icp->icmp_type]++;
374 code = icp->icmp_code;
375 switch (icp->icmp_type) {
379 case ICMP_UNREACH_NET:
380 case ICMP_UNREACH_HOST:
381 case ICMP_UNREACH_SRCFAIL:
382 case ICMP_UNREACH_NET_UNKNOWN:
383 case ICMP_UNREACH_HOST_UNKNOWN:
384 case ICMP_UNREACH_ISOLATED:
385 case ICMP_UNREACH_TOSNET:
386 case ICMP_UNREACH_TOSHOST:
387 case ICMP_UNREACH_HOST_PRECEDENCE:
388 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
389 code = PRC_UNREACH_NET;
392 case ICMP_UNREACH_NEEDFRAG:
397 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
398 * Treat subcodes 2,3 as immediate RST
400 case ICMP_UNREACH_PROTOCOL:
401 case ICMP_UNREACH_PORT:
402 code = PRC_UNREACH_PORT;
405 case ICMP_UNREACH_NET_PROHIB:
406 case ICMP_UNREACH_HOST_PROHIB:
407 case ICMP_UNREACH_FILTER_PROHIB:
408 code = PRC_UNREACH_ADMIN_PROHIB;
419 code += PRC_TIMXCEED_INTRANS;
425 code = PRC_PARAMPROB;
428 case ICMP_SOURCEQUENCH:
434 * Problem with datagram; advise higher level routines.
436 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
437 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
438 V_icmpstat.icps_badlen++;
441 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
442 /* Discard ICMP's in response to multicast packets */
443 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
447 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
449 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
451 * XXX if the packet contains [IPv4 AH TCP], we can't make a
452 * notification to TCP layer.
454 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
456 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
457 (void *)&icp->icmp_ip);
461 V_icmpstat.icps_badcode++;
466 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
467 V_icmpstat.icps_bmcastecho++;
470 icp->icmp_type = ICMP_ECHOREPLY;
471 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
478 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
479 V_icmpstat.icps_bmcasttstamp++;
482 if (icmplen < ICMP_TSLEN) {
483 V_icmpstat.icps_badlen++;
486 icp->icmp_type = ICMP_TSTAMPREPLY;
487 icp->icmp_rtime = iptime();
488 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
489 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
495 if (icmpmaskrepl == 0)
498 * We are not able to respond with all ones broadcast
499 * unless we receive it over a point-to-point interface.
501 if (icmplen < ICMP_MASKLEN)
503 switch (ip->ip_dst.s_addr) {
505 case INADDR_BROADCAST:
507 icmpdst.sin_addr = ip->ip_src;
511 icmpdst.sin_addr = ip->ip_dst;
513 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
514 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
519 icp->icmp_type = ICMP_MASKREPLY;
520 if (icmpmaskfake == 0)
521 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
523 icp->icmp_mask = icmpmaskfake;
524 if (ip->ip_src.s_addr == 0) {
525 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
526 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
527 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
528 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
531 ip->ip_len += hlen; /* since ip_input deducts this */
532 V_icmpstat.icps_reflect++;
533 V_icmpstat.icps_outhist[icp->icmp_type]++;
541 src = ntohl(ip->ip_src.s_addr);
542 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
543 gw = ntohl(icp->icmp_gwaddr.s_addr);
544 printf("icmp redirect from %d.%d.%d.%d: "
545 "%d.%d.%d.%d => %d.%d.%d.%d\n",
546 (int)(src >> 24), (int)((src >> 16) & 0xff),
547 (int)((src >> 8) & 0xff), (int)(src & 0xff),
548 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
549 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
550 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
551 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
554 * RFC1812 says we must ignore ICMP redirects if we
555 * are acting as router.
557 if (drop_redirect || V_ipforwarding)
561 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
562 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
563 V_icmpstat.icps_badlen++;
567 * Short circuit routing redirects to force
568 * immediate change in the kernel's routing
569 * tables. The message is also handed to anyone
570 * listening on a raw socket (e.g. the routing
571 * daemon for use in updating its tables).
573 icmpgw.sin_addr = ip->ip_src;
574 icmpdst.sin_addr = icp->icmp_gwaddr;
577 char buf[4 * sizeof "123"];
578 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
580 printf("redirect dst %s to %s\n",
581 buf, inet_ntoa(icp->icmp_gwaddr));
584 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
585 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
586 in_rtredirect((struct sockaddr *)&icmpsrc,
587 (struct sockaddr *)&icmpdst,
588 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
589 (struct sockaddr *)&icmpgw, fibnum);
591 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
593 key_sa_routechange((struct sockaddr *)&icmpsrc);
598 * No kernel processing for the following;
599 * just fall through to send to raw listener.
602 case ICMP_ROUTERADVERT:
603 case ICMP_ROUTERSOLICIT:
604 case ICMP_TSTAMPREPLY:
620 * Reflect the ip packet back to the source
623 icmp_reflect(struct mbuf *m)
625 struct ip *ip = mtod(m, struct ip *);
628 struct in_ifaddr *ia;
630 struct mbuf *opts = 0;
631 int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
633 if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
634 IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
635 IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
636 m_freem(m); /* Bad return address */
637 V_icmpstat.icps_badaddr++;
638 goto done; /* Ip_output() will check for broadcast */
642 ip->ip_dst = ip->ip_src;
645 * Source selection for ICMP replies:
647 * If the incoming packet was addressed directly to one of our
648 * own addresses, use dst as the src for the reply.
650 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash)
651 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
654 * If the incoming packet was addressed to one of our broadcast
655 * addresses, use the first non-broadcast address which corresponds
656 * to the incoming interface.
658 if (m->m_pkthdr.rcvif != NULL &&
659 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
660 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
661 if (ifa->ifa_addr->sa_family != AF_INET)
664 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
670 * If the packet was transiting through us, use the address of
671 * the interface the packet came through in. If that interface
672 * doesn't have a suitable IP address, the normal selection
675 if (icmp_rfi && m->m_pkthdr.rcvif != NULL) {
676 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
677 if (ifa->ifa_addr->sa_family != AF_INET)
684 * If the incoming packet was not addressed directly to us, use
685 * designated interface for icmp replies specified by sysctl
686 * net.inet.icmp.reply_src (default not set). Otherwise continue
687 * with normal source selection.
689 if (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) {
690 TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) {
691 if (ifa->ifa_addr->sa_family != AF_INET)
698 * If the packet was transiting through us, use the address of
699 * the interface that is the closest to the packet source.
700 * When we don't have a route back to the packet source, stop here
701 * and drop the packet.
703 ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
706 V_icmpstat.icps_noroute++;
711 mac_netinet_icmp_replyinplace(m);
713 t = IA_SIN(ia)->sin_addr;
715 ip->ip_ttl = V_ip_defttl;
723 * Retrieve any source routing from the incoming packet;
724 * add on any record-route or timestamp options.
726 cp = (u_char *) (ip + 1);
727 if ((opts = ip_srcroute(m)) == 0 &&
728 (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
729 opts->m_len = sizeof(struct in_addr);
730 mtod(opts, struct in_addr *)->s_addr = 0;
735 printf("icmp_reflect optlen %d rt %d => ",
736 optlen, opts->m_len);
738 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
739 opt = cp[IPOPT_OPTVAL];
740 if (opt == IPOPT_EOL)
742 if (opt == IPOPT_NOP)
745 if (cnt < IPOPT_OLEN + sizeof(*cp))
747 len = cp[IPOPT_OLEN];
748 if (len < IPOPT_OLEN + sizeof(*cp) ||
753 * Should check for overflow, but it "can't happen"
755 if (opt == IPOPT_RR || opt == IPOPT_TS ||
756 opt == IPOPT_SECURITY) {
758 mtod(opts, caddr_t) + opts->m_len, len);
762 /* Terminate & pad, if necessary */
763 cnt = opts->m_len % 4;
765 for (; cnt < 4; cnt++) {
766 *(mtod(opts, caddr_t) + opts->m_len) =
773 printf("%d\n", opts->m_len);
777 * Now strip out original options by copying rest of first
778 * mbuf's data back, and adjust the IP length.
780 ip->ip_len -= optlen;
781 ip->ip_v = IPVERSION;
784 if (m->m_flags & M_PKTHDR)
785 m->m_pkthdr.len -= optlen;
786 optlen += sizeof(struct ip);
787 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
788 (unsigned)(m->m_len - sizeof(struct ip)));
790 m_tag_delete_nonpersistent(m);
791 m->m_flags &= ~(M_BCAST|M_MCAST);
799 * Send an icmp packet back to the ip level,
800 * after supplying a checksum.
803 icmp_send(struct mbuf *m, struct mbuf *opts)
805 register struct ip *ip = mtod(m, struct ip *);
807 register struct icmp *icp;
809 hlen = ip->ip_hl << 2;
812 icp = mtod(m, struct icmp *);
814 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
817 m->m_pkthdr.rcvif = (struct ifnet *)0;
820 char buf[4 * sizeof "123"];
821 strcpy(buf, inet_ntoa(ip->ip_dst));
822 printf("icmp_send dst %s src %s\n",
823 buf, inet_ntoa(ip->ip_src));
826 (void) ip_output(m, opts, NULL, 0, NULL, NULL);
836 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
841 * Return the next larger or smaller MTU plateau (table from RFC 1191)
842 * given current value MTU. If DIR is less than zero, a larger plateau
843 * is returned; otherwise, a smaller value is returned.
846 ip_next_mtu(int mtu, int dir)
848 static int mtutab[] = {
849 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
854 size = (sizeof mtutab) / (sizeof mtutab[0]);
856 for (i = 0; i < size; i++)
860 for (i = size - 1; i >= 0; i--)
863 if (mtu == mtutab[0])
871 * badport_bandlim() - check for ICMP bandwidth limit
873 * Return 0 if it is ok to send an ICMP error response, -1 if we have
874 * hit our bandwidth limit and it is not ok.
876 * If icmplim is <= 0, the feature is disabled and 0 is returned.
878 * For now we separate the TCP and UDP subsystems w/ different 'which'
879 * values. We may eventually remove this separation (and simplify the
882 * Note that the printing of the error message is delayed so we can
883 * properly print the icmp error rate that the system was trying to do
884 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
885 * the 'final' error, but it doesn't make sense to solve the printing
886 * delay with more complex code.
890 badport_bandlim(int which)
892 #define N(a) (sizeof (a) / sizeof (a[0]))
895 struct timeval lasttime;
897 } rates[BANDLIM_MAX+1] = {
898 { "icmp unreach response" },
899 { "icmp ping response" },
900 { "icmp tstamp response" },
901 { "closed port RST response" },
902 { "open port RST response" },
903 { "icmp6 unreach response" }
907 * Return ok status if feature disabled or argument out of range.
909 if (icmplim > 0 && (u_int) which < N(rates)) {
910 struct rate *r = &rates[which];
911 int opps = r->curpps;
913 if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim))
914 return -1; /* discard packet */
916 * If we've dropped below the threshold after having
917 * rate-limited traffic print the message. This preserves
918 * the previous behaviour at the expense of added complexity.
920 if (icmplim_output && opps > icmplim)
921 printf("Limiting %s from %d to %d packets/sec\n",
922 r->type, opps, icmplim);
924 return 0; /* okay to send packet */