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
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
34 * $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.39.2.19 2003/01/24 05:11:34 sam Exp $
37 #include "opt_ipsec.h"
39 #include <sys/param.h>
40 #include <sys/systm.h>
42 #include <sys/protosw.h>
43 #include <sys/socket.h>
44 #include <sys/socketops.h>
46 #include <sys/kernel.h>
47 #include <sys/sysctl.h>
48 #include <sys/in_cksum.h>
50 #include <machine/stdarg.h>
53 #include <net/if_types.h>
54 #include <net/route.h>
57 #include <netinet/in.h>
58 #include <netinet/in_systm.h>
59 #include <netinet/in_var.h>
60 #include <netinet/ip.h>
61 #include <netinet/ip_icmp.h>
62 #include <netinet/ip_var.h>
63 #include <netinet/icmp_var.h>
66 #include <netinet6/ipsec.h>
67 #include <netproto/key/key.h>
71 #include <netproto/ipsec/ipsec.h>
72 #include <netproto/ipsec/key.h>
77 * ICMP routines: error generation, receive packet processing, and
78 * routines to turnaround packets back to the originator, and
79 * host table maintenance routines.
82 struct icmpstat icmpstat;
83 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
84 &icmpstat, icmpstat, "ICMP statistics");
86 static int icmpmaskrepl = 0;
87 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
88 &icmpmaskrepl, 0, "Allow replies to netmask requests");
90 static int drop_redirect = 0;
91 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
92 &drop_redirect, 0, "Ignore ICMP redirects");
94 static int log_redirect = 0;
95 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
96 &log_redirect, 0, "Enable output about ICMP redirects");
98 static int discard_sourcequench = 1;
99 SYSCTL_INT(_net_inet_icmp, OID_AUTO, discard_sourcequench, CTLFLAG_RW,
100 &discard_sourcequench, 0, "Discard ICMP Source Quench");
105 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl
106 * variable content is -1 and read-only.
109 static int icmplim = 200;
110 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
111 &icmplim, 0, "ICMP bandwidth limit");
114 static int icmplim = -1;
115 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD,
116 &icmplim, 0, "ICMP bandwidth limit");
120 static int icmplim_output = 0;
121 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
122 &icmplim_output, 0, "Enable output about ICMP bandwidth limits");
125 * ICMP broadcast echo sysctl
128 static int icmpbmcastecho = 0;
129 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
130 &icmpbmcastecho, 0, "");
132 static char icmp_reply_src[IFNAMSIZ];
133 SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
134 icmp_reply_src, IFNAMSIZ, "icmp reply source for non-local packets.");
137 SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
138 &icmp_rfi, 0, "ICMP reply from incoming interface for "
139 "non-local packets");
145 static void icmp_reflect (struct mbuf *);
146 static void icmp_send (struct mbuf *, struct mbuf *, struct route *);
148 extern struct protosw inetsw[];
151 * Generate an error packet of type error
152 * in response to bad packet ip.
155 icmp_error(struct mbuf *n, int type, int code, n_long dest, int destmtu)
157 struct ip *oip = mtod(n, struct ip *), *nip;
158 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
165 kprintf("icmp_error(%p, %d, %d)\n", oip, type, code);
167 if (type != ICMP_REDIRECT)
168 icmpstat.icps_error++;
170 * Don't send error if the original packet was encrypted.
171 * Don't send error if not the first fragment of message.
172 * Don't error if the old packet protocol was ICMP
173 * error message, only known informational types.
175 if (n->m_flags & M_DECRYPTED)
177 if (oip->ip_off &~ (IP_MF|IP_DF))
179 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
180 n->m_len >= oiplen + ICMP_MINLEN &&
181 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
182 icmpstat.icps_oldicmp++;
185 /* Don't send error in response to a multicast or broadcast packet */
186 if (n->m_flags & (M_BCAST|M_MCAST))
189 * First, formulate icmp message
191 m = m_gethdr(MB_DONTWAIT, MT_HEADER);
194 icmplen = min(oiplen + 8, oip->ip_len);
195 if (icmplen < sizeof(struct ip))
196 panic("icmp_error: bad length");
197 m->m_len = icmplen + ICMP_MINLEN;
198 MH_ALIGN(m, m->m_len);
199 icp = mtod(m, struct icmp *);
200 if ((u_int)type > ICMP_MAXTYPE)
202 icmpstat.icps_outhist[type]++;
203 icp->icmp_type = type;
204 if (type == ICMP_REDIRECT)
205 icp->icmp_gwaddr.s_addr = dest;
209 * The following assignments assume an overlay with the
210 * zeroed icmp_void field.
212 if (type == ICMP_PARAMPROB) {
213 icp->icmp_pptr = code;
215 } else if (type == ICMP_UNREACH &&
216 code == ICMP_UNREACH_NEEDFRAG && destmtu) {
217 icp->icmp_nextmtu = htons(destmtu);
221 icp->icmp_code = code;
222 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
226 * Convert fields to network representation.
228 nip->ip_len = htons(nip->ip_len);
229 nip->ip_off = htons(nip->ip_off);
232 * Now, copy old ip header (without options)
233 * in front of icmp message.
235 if (m->m_data - sizeof(struct ip) < m->m_pktdat)
237 m->m_data -= sizeof(struct ip);
238 m->m_len += sizeof(struct ip);
239 m->m_pkthdr.len = m->m_len;
240 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
241 nip = mtod(m, struct ip *);
242 bcopy(oip, nip, sizeof(struct ip));
243 nip->ip_len = m->m_len;
244 nip->ip_vhl = IP_VHL_BORING;
245 nip->ip_p = IPPROTO_ICMP;
247 m->m_pkthdr.fw_flags |= n->m_pkthdr.fw_flags & FW_MBUF_GENERATED;
255 * Process a received ICMP message.
258 icmp_input(struct mbuf **mp, int *offp, int proto)
260 struct sockaddr_in icmpsrc = { sizeof(struct sockaddr_in), AF_INET };
261 struct sockaddr_in icmpdst = { sizeof(struct sockaddr_in), AF_INET };
262 struct sockaddr_in icmpgw = { sizeof(struct sockaddr_in), AF_INET };
264 struct in_ifaddr *ia;
265 struct mbuf *m = *mp;
266 struct ip *ip = mtod(m, struct ip *);
267 int icmplen = ip->ip_len;
275 * Locate icmp structure in mbuf, and check
276 * that not corrupted and of at least minimum length.
280 char buf[sizeof "aaa.bbb.ccc.ddd"];
282 strcpy(buf, inet_ntoa(ip->ip_src));
283 kprintf("icmp_input from %s to %s, len %d\n",
284 buf, inet_ntoa(ip->ip_dst), icmplen);
287 if (icmplen < ICMP_MINLEN) {
288 icmpstat.icps_tooshort++;
291 i = hlen + min(icmplen, ICMP_ADVLENMIN);
292 if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
293 icmpstat.icps_tooshort++;
294 return(IPPROTO_DONE);
296 ip = mtod(m, struct ip *);
299 icp = mtod(m, struct icmp *);
300 if (in_cksum(m, icmplen)) {
301 icmpstat.icps_checksum++;
307 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
309 * Deliver very specific ICMP type only.
311 switch (icp->icmp_type) {
322 kprintf("icmp_input, type %d code %d\n", icp->icmp_type,
327 * Message type specific processing.
329 if (icp->icmp_type > ICMP_MAXTYPE)
331 icmpstat.icps_inhist[icp->icmp_type]++;
332 code = icp->icmp_code;
333 switch (icp->icmp_type) {
337 case ICMP_UNREACH_NET:
338 case ICMP_UNREACH_HOST:
339 case ICMP_UNREACH_SRCFAIL:
340 case ICMP_UNREACH_NET_UNKNOWN:
341 case ICMP_UNREACH_HOST_UNKNOWN:
342 case ICMP_UNREACH_ISOLATED:
343 case ICMP_UNREACH_TOSNET:
344 case ICMP_UNREACH_TOSHOST:
345 case ICMP_UNREACH_HOST_PRECEDENCE:
346 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
347 code = PRC_UNREACH_NET;
350 case ICMP_UNREACH_NEEDFRAG:
355 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
356 * Treat subcodes 2,3 as immediate RST
358 case ICMP_UNREACH_PROTOCOL:
359 case ICMP_UNREACH_PORT:
360 code = PRC_UNREACH_PORT;
363 case ICMP_UNREACH_NET_PROHIB:
364 case ICMP_UNREACH_HOST_PROHIB:
365 case ICMP_UNREACH_FILTER_PROHIB:
366 code = PRC_UNREACH_ADMIN_PROHIB;
377 code += PRC_TIMXCEED_INTRANS;
383 code = PRC_PARAMPROB;
386 case ICMP_SOURCEQUENCH:
389 if (discard_sourcequench)
394 * Problem with datagram; advise higher level routines.
396 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
397 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
398 icmpstat.icps_badlen++;
401 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
402 /* Discard ICMP's in response to multicast packets */
403 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
407 kprintf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
409 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
413 * If we got a needfrag and there is a host route to the
414 * original destination, and the MTU is not locked, then
415 * set the MTU in the route to the suggested new value
416 * (if given) and then notify as usual. The ULPs will
417 * notice that the MTU has changed and adapt accordingly.
418 * If no new MTU was suggested, then we guess a new one
419 * less than the current value. If the new MTU is
420 * unreasonably small (arbitrarily set at 296), then
421 * we reset the MTU to the interface value and enable the
422 * lock bit, indicating that we are no longer doing MTU
425 if (code == PRC_MSGSIZE) {
429 rt = rtpurelookup((struct sockaddr *)&icmpsrc);
430 if (rt != NULL && (rt->rt_flags & RTF_HOST) &&
431 !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
432 mtu = ntohs(icp->icmp_nextmtu);
434 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
437 kprintf("MTU for %s reduced to %d\n",
438 inet_ntoa(icmpsrc.sin_addr), mtu);
441 /* rt->rt_rmx.rmx_mtu =
442 rt->rt_ifp->if_mtu; */
443 rt->rt_rmx.rmx_locks |= RTV_MTU;
444 } else if (rt->rt_rmx.rmx_mtu > mtu) {
445 rt->rt_rmx.rmx_mtu = mtu;
453 * XXX if the packet contains [IPv4 AH TCP], we can't make a
454 * notification to TCP layer.
457 &inetsw[ip_protox[icp->icmp_ip.ip_p]],
458 code, (struct sockaddr *)&icmpsrc, &icp->icmp_ip);
462 icmpstat.icps_badcode++;
467 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
468 icmpstat.icps_bmcastecho++;
471 icp->icmp_type = ICMP_ECHOREPLY;
473 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
481 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
482 icmpstat.icps_bmcasttstamp++;
485 if (icmplen < ICMP_TSLEN) {
486 icmpstat.icps_badlen++;
489 icp->icmp_type = ICMP_TSTAMPREPLY;
490 icp->icmp_rtime = iptime();
491 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
493 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
500 if (icmpmaskrepl == 0)
503 * We are not able to respond with all ones broadcast
504 * unless we receive it over a point-to-point interface.
506 if (icmplen < ICMP_MASKLEN)
508 switch (ip->ip_dst.s_addr) {
510 case INADDR_BROADCAST:
512 icmpdst.sin_addr = ip->ip_src;
516 icmpdst.sin_addr = ip->ip_dst;
518 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
519 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
524 icp->icmp_type = ICMP_MASKREPLY;
525 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
526 if (ip->ip_src.s_addr == 0) {
527 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
528 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
529 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
530 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
533 ip->ip_len += hlen; /* since ip_input deducts this */
534 icmpstat.icps_reflect++;
535 icmpstat.icps_outhist[icp->icmp_type]++;
537 return(IPPROTO_DONE);
543 src = ntohl(ip->ip_src.s_addr);
544 dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
545 gw = ntohl(icp->icmp_gwaddr.s_addr);
546 kprintf("icmp redirect from %d.%d.%d.%d: "
547 "%d.%d.%d.%d => %d.%d.%d.%d\n",
548 (int)(src >> 24), (int)((src >> 16) & 0xff),
549 (int)((src >> 8) & 0xff), (int)(src & 0xff),
550 (int)(dst >> 24), (int)((dst >> 16) & 0xff),
551 (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
552 (int)(gw >> 24), (int)((gw >> 16) & 0xff),
553 (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
559 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
560 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
561 icmpstat.icps_badlen++;
565 * Short circuit routing redirects to force
566 * immediate change in the kernel's routing
567 * tables. The message is also handed to anyone
568 * listening on a raw socket (e.g. the routing
569 * daemon for use in updating its tables).
571 icmpgw.sin_addr = ip->ip_src;
572 icmpdst.sin_addr = icp->icmp_gwaddr;
575 char buf[sizeof "aaa.bbb.ccc.ddd"];
577 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
578 kprintf("redirect dst %s to %s\n",
579 buf, inet_ntoa(icp->icmp_gwaddr));
582 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
583 rtredirect((struct sockaddr *)&icmpsrc,
584 (struct sockaddr *)&icmpdst,
585 NULL, RTF_GATEWAY | RTF_HOST,
586 (struct sockaddr *)&icmpgw);
587 kpfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
589 key_sa_routechange((struct sockaddr *)&icmpsrc);
594 * No kernel processing for the following;
595 * just fall through to send to raw listener.
598 case ICMP_ROUTERADVERT:
599 case ICMP_ROUTERSOLICIT:
600 case ICMP_TSTAMPREPLY:
609 rip_input(mp, offp, proto);
610 return(IPPROTO_DONE);
614 return(IPPROTO_DONE);
618 * Reflect the ip packet back to the source
621 icmp_reflect(struct mbuf *m)
623 struct ip *ip = mtod(m, struct ip *);
624 struct in_ifaddr *ia;
625 struct in_ifaddr_container *iac;
626 struct ifaddr_container *ifac;
629 struct mbuf *opts = NULL;
630 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
631 struct route *ro = NULL, rt;
633 if (!in_canforward(ip->ip_src) &&
634 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
635 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
636 m_freem(m); /* Bad return address */
637 icmpstat.icps_badaddr++;
638 goto done; /* Ip_output() will check for broadcast */
641 ip->ip_dst = ip->ip_src;
644 bzero(ro, sizeof *ro);
647 * If the incoming packet was addressed directly to us,
648 * use dst as the src for the reply. Otherwise (broadcast
649 * or anonymous), use the address which corresponds
650 * to the incoming interface.
653 LIST_FOREACH(iac, INADDR_HASH(t.s_addr), ia_hash) {
654 if (t.s_addr == IA_SIN(iac->ia)->sin_addr.s_addr) {
659 ifp = m->m_pkthdr.rcvif;
660 if (ifp != NULL && (ifp->if_flags & IFF_BROADCAST)) {
661 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
662 struct ifaddr *ifa = ifac->ifa;
664 if (ifa->ifa_addr->sa_family != AF_INET)
667 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
673 * If the packet was transiting through us, use the address of
674 * the interface the packet came through in. If that interface
675 * doesn't have a suitable IP address, the normal selection
678 if (icmp_rfi && ifp != NULL) {
679 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
680 struct ifaddr *ifa = ifac->ifa;
682 if (ifa->ifa_addr->sa_family != AF_INET)
689 * If the incoming packet was not addressed directly to us, use
690 * designated interface for icmp replies specified by sysctl
691 * net.inet.icmp.reply_src (default not set). Otherwise continue
692 * with normal source selection.
694 if (icmp_reply_src[0] != '\0' && (ifp = ifunit(icmp_reply_src))) {
695 TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
696 struct ifaddr *ifa = ifac->ifa;
698 if (ifa->ifa_addr->sa_family != AF_INET)
705 * If the packet was transiting through us, use the address of
706 * the interface that is the closest to the packet source.
707 * When we don't have a route back to the packet source, stop here
708 * and drop the packet.
710 ia = ip_rtaddr(ip->ip_dst, ro);
713 icmpstat.icps_noroute++;
717 t = IA_SIN(ia)->sin_addr;
719 ip->ip_ttl = ip_defttl;
727 * Retrieve any source routing from the incoming packet;
728 * add on any record-route or timestamp options.
730 cp = (u_char *) (ip + 1);
731 if ((opts = ip_srcroute(m)) == NULL &&
732 (opts = m_gethdr(MB_DONTWAIT, MT_HEADER))) {
733 opts->m_len = sizeof(struct in_addr);
734 mtod(opts, struct in_addr *)->s_addr = 0;
739 kprintf("icmp_reflect optlen %d rt %d => ",
740 optlen, opts->m_len);
742 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
743 opt = cp[IPOPT_OPTVAL];
744 if (opt == IPOPT_EOL)
746 if (opt == IPOPT_NOP)
749 if (cnt < IPOPT_OLEN + sizeof *cp)
751 len = cp[IPOPT_OLEN];
752 if (len < IPOPT_OLEN + sizeof *cp ||
757 * Should check for overflow, but it
760 if (opt == IPOPT_RR || opt == IPOPT_TS ||
761 opt == IPOPT_SECURITY) {
763 mtod(opts, caddr_t) + opts->m_len,
768 /* Terminate & pad, if necessary */
769 cnt = opts->m_len % 4;
771 for (; cnt < 4; cnt++) {
772 *(mtod(opts, caddr_t) + opts->m_len) =
779 kprintf("%d\n", opts->m_len);
783 * Now strip out original options by copying rest of first
784 * mbuf's data back, and adjust the IP length.
786 ip->ip_len -= optlen;
787 ip->ip_vhl = IP_VHL_BORING;
789 if (m->m_flags & M_PKTHDR)
790 m->m_pkthdr.len -= optlen;
791 optlen += sizeof(struct ip);
792 bcopy((caddr_t)ip + optlen, ip + 1,
793 m->m_len - sizeof(struct ip));
795 m->m_pkthdr.fw_flags &= FW_MBUF_GENERATED;
796 m->m_flags &= ~(M_BCAST|M_MCAST);
797 icmp_send(m, opts, ro);
806 * Send an icmp packet back to the ip level,
807 * after supplying a checksum.
810 icmp_send(struct mbuf *m, struct mbuf *opts, struct route *rt)
812 struct ip *ip = mtod(m, struct ip *);
816 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
819 icp = mtod(m, struct icmp *);
821 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
824 m->m_pkthdr.rcvif = NULL;
827 char buf[sizeof "aaa.bbb.ccc.ddd"];
829 strcpy(buf, inet_ntoa(ip->ip_dst));
830 kprintf("icmp_send dst %s src %s\n", buf, inet_ntoa(ip->ip_src));
833 ip_output(m, opts, rt, 0, NULL, NULL);
843 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
849 * Return the next larger or smaller MTU plateau (table from RFC 1191)
850 * given current value MTU. If DIR is less than zero, a larger plateau
851 * is returned; otherwise, a smaller value is returned.
854 ip_next_mtu(int mtu, int dir)
856 static int mtutab[] = {
857 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
862 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
863 if (mtu >= mtutab[i])
871 return mtutab[i - 1];
874 if (mtutab[i] == 0) {
876 } else if(mtu > mtutab[i]) {
879 return mtutab[i + 1];
887 * badport_bandlim() - check for ICMP bandwidth limit
889 * Return 0 if it is ok to send an ICMP error response, -1 if we have
890 * hit our bandwidth limit and it is not ok.
892 * If icmplim is <= 0, the feature is disabled and 0 is returned.
894 * For now we separate the TCP and UDP subsystems w/ different 'which'
895 * values. We may eventually remove this separation (and simplify the
898 * Note that the printing of the error message is delayed so we can
899 * properly print the icmp error rate that the system was trying to do
900 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing
901 * the 'final' error, but it doesn't make sense to solve the printing
902 * delay with more complex code.
905 badport_bandlim(int which)
907 static int lticks[BANDLIM_MAX + 1];
908 static int lpackets[BANDLIM_MAX + 1];
910 const char *bandlimittype[] = {
911 "Limiting icmp unreach response",
912 "Limiting icmp ping response",
913 "Limiting icmp tstamp response",
914 "Limiting closed port RST response",
915 "Limiting open port RST response"
919 * Return ok status if feature disabled or argument out of
923 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0)
925 dticks = ticks - lticks[which];
928 * reset stats when cumulative dt exceeds one second.
931 if ((unsigned int)dticks > hz) {
932 if (lpackets[which] > icmplim && icmplim_output) {
933 kprintf("%s from %d to %d packets per second\n",
934 bandlimittype[which],
939 lticks[which] = ticks;
947 if (++lpackets[which] > icmplim) {