/* * Copyright (c) 1982, 1986, 1988, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 * $FreeBSD$ */ #include "opt_ipsec.h" #include "opt_mac.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef IPSEC #include #include #endif #ifdef FAST_IPSEC #include #include #define IPSEC #endif #include /* * ICMP routines: error generation, receive packet processing, and * routines to turnaround packets back to the originator, and * host table maintenance routines. */ static struct icmpstat icmpstat; SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, &icmpstat, icmpstat, ""); static int icmpmaskrepl = 0; SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); static u_int icmpmaskfake = 0; SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); static int drop_redirect = 0; SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, &drop_redirect, 0, ""); static int log_redirect = 0; SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, &log_redirect, 0, ""); static int icmplim = 200; SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, &icmplim, 0, ""); static int icmplim_output = 1; SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, &icmplim_output, 0, ""); /* * ICMP broadcast echo sysctl */ static int icmpbmcastecho = 0; SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, &icmpbmcastecho, 0, ""); #ifdef ICMPPRINTFS int icmpprintfs = 0; #endif static void icmp_reflect(struct mbuf *); static void icmp_send(struct mbuf *, struct mbuf *); static int ip_next_mtu(int, int); extern struct protosw inetsw[]; /* * Generate an error packet of type error * in response to bad packet ip. */ void icmp_error(n, type, code, dest, destifp) struct mbuf *n; int type, code; n_long dest; struct ifnet *destifp; { register struct ip *oip = mtod(n, struct ip *), *nip; register unsigned oiplen = oip->ip_hl << 2; register struct icmp *icp; register struct mbuf *m; unsigned icmplen; #ifdef ICMPPRINTFS if (icmpprintfs) printf("icmp_error(%p, %x, %d)\n", oip, type, code); #endif if (type != ICMP_REDIRECT) icmpstat.icps_error++; /* * Don't send error if not the first fragment of message. * Don't error if the old packet protocol was ICMP * error message, only known informational types. */ if (oip->ip_off &~ (IP_MF|IP_DF)) goto freeit; if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && n->m_len >= oiplen + ICMP_MINLEN && !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { icmpstat.icps_oldicmp++; goto freeit; } /* Don't send error in response to a multicast or broadcast packet */ if (n->m_flags & (M_BCAST|M_MCAST)) goto freeit; /* * First, formulate icmp message */ m = m_gethdr(M_DONTWAIT, MT_HEADER); if (m == NULL) goto freeit; #ifdef MAC mac_create_mbuf_netlayer(n, m); #endif icmplen = min(oiplen + 8, oip->ip_len); if (icmplen < sizeof(struct ip)) panic("icmp_error: bad length"); m->m_len = icmplen + ICMP_MINLEN; MH_ALIGN(m, m->m_len); icp = mtod(m, struct icmp *); if ((u_int)type > ICMP_MAXTYPE) panic("icmp_error"); icmpstat.icps_outhist[type]++; icp->icmp_type = type; if (type == ICMP_REDIRECT) icp->icmp_gwaddr.s_addr = dest; else { icp->icmp_void = 0; /* * The following assignments assume an overlay with the * zeroed icmp_void field. */ if (type == ICMP_PARAMPROB) { icp->icmp_pptr = code; code = 0; } else if (type == ICMP_UNREACH && code == ICMP_UNREACH_NEEDFRAG && destifp) { icp->icmp_nextmtu = htons(destifp->if_mtu); } } icp->icmp_code = code; m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); nip = &icp->icmp_ip; /* * Convert fields to network representation. */ nip->ip_len = htons(nip->ip_len); nip->ip_off = htons(nip->ip_off); /* * Now, copy old ip header (without options) * in front of icmp message. */ if (m->m_data - sizeof(struct ip) < m->m_pktdat) panic("icmp len"); m->m_data -= sizeof(struct ip); m->m_len += sizeof(struct ip); m->m_pkthdr.len = m->m_len; m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; nip = mtod(m, struct ip *); bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); nip->ip_len = m->m_len; nip->ip_v = IPVERSION; nip->ip_hl = 5; nip->ip_p = IPPROTO_ICMP; nip->ip_tos = 0; icmp_reflect(m); freeit: m_freem(n); } /* * Process a received ICMP message. */ void icmp_input(m, off) struct mbuf *m; int off; { struct icmp *icp; struct in_ifaddr *ia; struct ip *ip = mtod(m, struct ip *); struct sockaddr_in icmpsrc, icmpdst, icmpgw; int hlen = off; int icmplen = ip->ip_len; int i, code; void (*ctlfunc)(int, struct sockaddr *, void *); /* * Locate icmp structure in mbuf, and check * that not corrupted and of at least minimum length. */ #ifdef ICMPPRINTFS if (icmpprintfs) { char buf[4 * sizeof "123"]; strcpy(buf, inet_ntoa(ip->ip_src)); printf("icmp_input from %s to %s, len %d\n", buf, inet_ntoa(ip->ip_dst), icmplen); } #endif if (icmplen < ICMP_MINLEN) { icmpstat.icps_tooshort++; goto freeit; } i = hlen + min(icmplen, ICMP_ADVLENMIN); if (m->m_len < i && (m = m_pullup(m, i)) == 0) { icmpstat.icps_tooshort++; return; } ip = mtod(m, struct ip *); m->m_len -= hlen; m->m_data += hlen; icp = mtod(m, struct icmp *); if (in_cksum(m, icmplen)) { icmpstat.icps_checksum++; goto freeit; } m->m_len += hlen; m->m_data -= hlen; if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { /* * Deliver very specific ICMP type only. */ switch (icp->icmp_type) { case ICMP_UNREACH: case ICMP_TIMXCEED: break; default: goto freeit; } } #ifdef ICMPPRINTFS if (icmpprintfs) printf("icmp_input, type %d code %d\n", icp->icmp_type, icp->icmp_code); #endif /* * Message type specific processing. */ if (icp->icmp_type > ICMP_MAXTYPE) goto raw; /* Initialize */ bzero(&icmpsrc, sizeof(icmpsrc)); icmpsrc.sin_len = sizeof(struct sockaddr_in); icmpsrc.sin_family = AF_INET; bzero(&icmpdst, sizeof(icmpdst)); icmpdst.sin_len = sizeof(struct sockaddr_in); icmpdst.sin_family = AF_INET; bzero(&icmpgw, sizeof(icmpgw)); icmpgw.sin_len = sizeof(struct sockaddr_in); icmpgw.sin_family = AF_INET; icmpstat.icps_inhist[icp->icmp_type]++; code = icp->icmp_code; switch (icp->icmp_type) { case ICMP_UNREACH: switch (code) { case ICMP_UNREACH_NET: case ICMP_UNREACH_HOST: case ICMP_UNREACH_SRCFAIL: case ICMP_UNREACH_NET_UNKNOWN: case ICMP_UNREACH_HOST_UNKNOWN: case ICMP_UNREACH_ISOLATED: case ICMP_UNREACH_TOSNET: case ICMP_UNREACH_TOSHOST: case ICMP_UNREACH_HOST_PRECEDENCE: case ICMP_UNREACH_PRECEDENCE_CUTOFF: code = PRC_UNREACH_NET; break; case ICMP_UNREACH_NEEDFRAG: code = PRC_MSGSIZE; break; /* * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. * Treat subcodes 2,3 as immediate RST */ case ICMP_UNREACH_PROTOCOL: case ICMP_UNREACH_PORT: code = PRC_UNREACH_PORT; break; case ICMP_UNREACH_NET_PROHIB: case ICMP_UNREACH_HOST_PROHIB: case ICMP_UNREACH_FILTER_PROHIB: code = PRC_UNREACH_ADMIN_PROHIB; break; default: goto badcode; } goto deliver; case ICMP_TIMXCEED: if (code > 1) goto badcode; code += PRC_TIMXCEED_INTRANS; goto deliver; case ICMP_PARAMPROB: if (code > 1) goto badcode; code = PRC_PARAMPROB; goto deliver; case ICMP_SOURCEQUENCH: if (code) goto badcode; code = PRC_QUENCH; deliver: /* * Problem with datagram; advise higher level routines. */ if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { icmpstat.icps_badlen++; goto freeit; } icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len); /* Discard ICMP's in response to multicast packets */ if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) goto badcode; #ifdef ICMPPRINTFS if (icmpprintfs) printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); #endif icmpsrc.sin_addr = icp->icmp_ip.ip_dst; /* * MTU discovery: * If we got a needfrag and there is a host route to the * original destination, and the MTU is not locked, then * set the MTU in the route to the suggested new value * (if given) and then notify as usual. The ULPs will * notice that the MTU has changed and adapt accordingly. * If no new MTU was suggested, then we guess a new one * less than the current value. If the new MTU is * unreasonably small, then we don't update the MTU value. * * XXX: All this should be done in tcp_mtudisc() because * the way we do it now, everyone can send us bogus ICMP * MSGSIZE packets for any destination. By doing this far * higher in the chain we have a matching tcp connection. * Thus spoofing is much harder. However there is no easy * non-hackish way to pass the new MTU up to tcp_mtudisc(). * Also see next XXX regarding IPv4 AH TCP. */ if (code == PRC_MSGSIZE) { int mtu; struct in_conninfo inc; bzero(&inc, sizeof(inc)); inc.inc_flags = 0; /* IPv4 */ inc.inc_faddr = icmpsrc.sin_addr; mtu = ntohs(icp->icmp_nextmtu); if (!mtu) mtu = ip_next_mtu(mtu, 1); if (mtu >= 256 + sizeof(struct tcpiphdr)) tcp_hc_updatemtu(&inc, mtu); #ifdef DEBUG_MTUDISC printf("MTU for %s reduced to %d\n", inet_ntoa(icmpsrc.sin_addr), mtu); #endif } /* * XXX if the packet contains [IPv4 AH TCP], we can't make a * notification to TCP layer. */ ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; if (ctlfunc) (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, (void *)&icp->icmp_ip); break; badcode: icmpstat.icps_badcode++; break; case ICMP_ECHO: if (!icmpbmcastecho && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { icmpstat.icps_bmcastecho++; break; } icp->icmp_type = ICMP_ECHOREPLY; if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) goto freeit; else goto reflect; case ICMP_TSTAMP: if (!icmpbmcastecho && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { icmpstat.icps_bmcasttstamp++; break; } if (icmplen < ICMP_TSLEN) { icmpstat.icps_badlen++; break; } icp->icmp_type = ICMP_TSTAMPREPLY; icp->icmp_rtime = iptime(); icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) goto freeit; else goto reflect; case ICMP_MASKREQ: if (icmpmaskrepl == 0) break; /* * We are not able to respond with all ones broadcast * unless we receive it over a point-to-point interface. */ if (icmplen < ICMP_MASKLEN) break; switch (ip->ip_dst.s_addr) { case INADDR_BROADCAST: case INADDR_ANY: icmpdst.sin_addr = ip->ip_src; break; default: icmpdst.sin_addr = ip->ip_dst; } ia = (struct in_ifaddr *)ifaof_ifpforaddr( (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); if (ia == 0) break; if (ia->ia_ifp == 0) break; icp->icmp_type = ICMP_MASKREPLY; if (icmpmaskfake == 0) icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; else icp->icmp_mask = icmpmaskfake; if (ip->ip_src.s_addr == 0) { if (ia->ia_ifp->if_flags & IFF_BROADCAST) ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; } reflect: ip->ip_len += hlen; /* since ip_input deducts this */ icmpstat.icps_reflect++; icmpstat.icps_outhist[icp->icmp_type]++; icmp_reflect(m); return; case ICMP_REDIRECT: if (log_redirect) { u_long src, dst, gw; src = ntohl(ip->ip_src.s_addr); dst = ntohl(icp->icmp_ip.ip_dst.s_addr); gw = ntohl(icp->icmp_gwaddr.s_addr); printf("icmp redirect from %d.%d.%d.%d: " "%d.%d.%d.%d => %d.%d.%d.%d\n", (int)(src >> 24), (int)((src >> 16) & 0xff), (int)((src >> 8) & 0xff), (int)(src & 0xff), (int)(dst >> 24), (int)((dst >> 16) & 0xff), (int)((dst >> 8) & 0xff), (int)(dst & 0xff), (int)(gw >> 24), (int)((gw >> 16) & 0xff), (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); } if (drop_redirect) break; if (code > 3) goto badcode; if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { icmpstat.icps_badlen++; break; } /* * Short circuit routing redirects to force * immediate change in the kernel's routing * tables. The message is also handed to anyone * listening on a raw socket (e.g. the routing * daemon for use in updating its tables). */ icmpgw.sin_addr = ip->ip_src; icmpdst.sin_addr = icp->icmp_gwaddr; #ifdef ICMPPRINTFS if (icmpprintfs) { char buf[4 * sizeof "123"]; strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); printf("redirect dst %s to %s\n", buf, inet_ntoa(icp->icmp_gwaddr)); } #endif icmpsrc.sin_addr = icp->icmp_ip.ip_dst; rtredirect((struct sockaddr *)&icmpsrc, (struct sockaddr *)&icmpdst, (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, (struct sockaddr *)&icmpgw); pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); #ifdef IPSEC key_sa_routechange((struct sockaddr *)&icmpsrc); #endif break; /* * No kernel processing for the following; * just fall through to send to raw listener. */ case ICMP_ECHOREPLY: case ICMP_ROUTERADVERT: case ICMP_ROUTERSOLICIT: case ICMP_TSTAMPREPLY: case ICMP_IREQREPLY: case ICMP_MASKREPLY: default: break; } raw: rip_input(m, off); return; freeit: m_freem(m); } /* * Reflect the ip packet back to the source */ static void icmp_reflect(m) struct mbuf *m; { struct ip *ip = mtod(m, struct ip *); struct ifaddr *ifa; struct in_ifaddr *ia; struct in_addr t; struct mbuf *opts = 0; int optlen = (ip->ip_hl << 2) - sizeof(struct ip); if (!in_canforward(ip->ip_src) && ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { m_freem(m); /* Bad return address */ icmpstat.icps_badaddr++; goto done; /* Ip_output() will check for broadcast */ } t = ip->ip_dst; ip->ip_dst = ip->ip_src; /* * If the incoming packet was addressed directly to us, * use dst as the src for the reply. Otherwise (broadcast * or anonymous), use the address which corresponds * to the incoming interface. */ LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) goto match; if (m->m_pkthdr.rcvif != NULL && m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { if (ifa->ifa_addr->sa_family != AF_INET) continue; ia = ifatoia(ifa); if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == t.s_addr) goto match; } } ia = ip_rtaddr(ip->ip_dst); /* We need a route to do anything useful. */ if (ia == NULL) { m_freem(m); icmpstat.icps_noroute++; goto done; } match: #ifdef MAC mac_reflect_mbuf_icmp(m); #endif t = IA_SIN(ia)->sin_addr; ip->ip_src = t; ip->ip_ttl = ip_defttl; if (optlen > 0) { register u_char *cp; int opt, cnt; u_int len; /* * Retrieve any source routing from the incoming packet; * add on any record-route or timestamp options. */ cp = (u_char *) (ip + 1); if ((opts = ip_srcroute()) == 0 && (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { opts->m_len = sizeof(struct in_addr); mtod(opts, struct in_addr *)->s_addr = 0; } if (opts) { #ifdef ICMPPRINTFS if (icmpprintfs) printf("icmp_reflect optlen %d rt %d => ", optlen, opts->m_len); #endif for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { opt = cp[IPOPT_OPTVAL]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) len = 1; else { if (cnt < IPOPT_OLEN + sizeof(*cp)) break; len = cp[IPOPT_OLEN]; if (len < IPOPT_OLEN + sizeof(*cp) || len > cnt) break; } /* * Should check for overflow, but it "can't happen" */ if (opt == IPOPT_RR || opt == IPOPT_TS || opt == IPOPT_SECURITY) { bcopy((caddr_t)cp, mtod(opts, caddr_t) + opts->m_len, len); opts->m_len += len; } } /* Terminate & pad, if necessary */ cnt = opts->m_len % 4; if (cnt) { for (; cnt < 4; cnt++) { *(mtod(opts, caddr_t) + opts->m_len) = IPOPT_EOL; opts->m_len++; } } #ifdef ICMPPRINTFS if (icmpprintfs) printf("%d\n", opts->m_len); #endif } /* * Now strip out original options by copying rest of first * mbuf's data back, and adjust the IP length. */ ip->ip_len -= optlen; ip->ip_v = IPVERSION; ip->ip_hl = 5; m->m_len -= optlen; if (m->m_flags & M_PKTHDR) m->m_pkthdr.len -= optlen; optlen += sizeof(struct ip); bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), (unsigned)(m->m_len - sizeof(struct ip))); } m_tag_delete_nonpersistent(m); m->m_flags &= ~(M_BCAST|M_MCAST); icmp_send(m, opts); done: if (opts) (void)m_free(opts); } /* * Send an icmp packet back to the ip level, * after supplying a checksum. */ static void icmp_send(m, opts) register struct mbuf *m; struct mbuf *opts; { register struct ip *ip = mtod(m, struct ip *); register int hlen; register struct icmp *icp; hlen = ip->ip_hl << 2; m->m_data += hlen; m->m_len -= hlen; icp = mtod(m, struct icmp *); icp->icmp_cksum = 0; icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); m->m_data -= hlen; m->m_len += hlen; m->m_pkthdr.rcvif = (struct ifnet *)0; #ifdef ICMPPRINTFS if (icmpprintfs) { char buf[4 * sizeof "123"]; strcpy(buf, inet_ntoa(ip->ip_dst)); printf("icmp_send dst %s src %s\n", buf, inet_ntoa(ip->ip_src)); } #endif (void) ip_output(m, opts, NULL, 0, NULL, NULL); } n_time iptime() { struct timeval atv; u_long t; getmicrotime(&atv); t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; return (htonl(t)); } /* * Return the next larger or smaller MTU plateau (table from RFC 1191) * given current value MTU. If DIR is less than zero, a larger plateau * is returned; otherwise, a smaller value is returned. */ static int ip_next_mtu(mtu, dir) int mtu; int dir; { static int mtutab[] = { 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 68, 0 }; int i; for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { if (mtu >= mtutab[i]) break; } if (dir < 0) { if (i == 0) { return 0; } else { return mtutab[i - 1]; } } else { if (mtutab[i] == 0) { return 0; } else if(mtu > mtutab[i]) { return mtutab[i]; } else { return mtutab[i + 1]; } } } /* * badport_bandlim() - check for ICMP bandwidth limit * * Return 0 if it is ok to send an ICMP error response, -1 if we have * hit our bandwidth limit and it is not ok. * * If icmplim is <= 0, the feature is disabled and 0 is returned. * * For now we separate the TCP and UDP subsystems w/ different 'which' * values. We may eventually remove this separation (and simplify the * code further). * * Note that the printing of the error message is delayed so we can * properly print the icmp error rate that the system was trying to do * (i.e. 22000/100 pps, etc...). This can cause long delays in printing * the 'final' error, but it doesn't make sense to solve the printing * delay with more complex code. */ int badport_bandlim(int which) { #define N(a) (sizeof (a) / sizeof (a[0])) static struct rate { const char *type; struct timeval lasttime; int curpps;; } rates[BANDLIM_MAX+1] = { { "icmp unreach response" }, { "icmp ping response" }, { "icmp tstamp response" }, { "closed port RST response" }, { "open port RST response" } }; /* * Return ok status if feature disabled or argument out of range. */ if (icmplim > 0 && (u_int) which < N(rates)) { struct rate *r = &rates[which]; int opps = r->curpps; if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) return -1; /* discard packet */ /* * If we've dropped below the threshold after having * rate-limited traffic print the message. This preserves * the previous behaviour at the expense of added complexity. */ if (icmplim_output && opps > icmplim) printf("Limiting %s from %d to %d packets/sec\n", r->type, opps, icmplim); } return 0; /* okay to send packet */ #undef N }