ip_fastfwd.c revision 197952
1139823Simp/*- 2122702Sandre * Copyright (c) 2003 Andre Oppermann, Internet Business Solutions AG 3122702Sandre * All rights reserved. 4122702Sandre * 5122702Sandre * Redistribution and use in source and binary forms, with or without 6122702Sandre * modification, are permitted provided that the following conditions 7122702Sandre * are met: 8122702Sandre * 1. Redistributions of source code must retain the above copyright 9122702Sandre * notice, this list of conditions and the following disclaimer. 10122702Sandre * 2. Redistributions in binary form must reproduce the above copyright 11122702Sandre * notice, this list of conditions and the following disclaimer in the 12122702Sandre * documentation and/or other materials provided with the distribution. 13122702Sandre * 3. The name of the author may not be used to endorse or promote 14122702Sandre * products derived from this software without specific prior written 15122702Sandre * permission. 16122702Sandre * 17122702Sandre * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18122702Sandre * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19122702Sandre * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20122702Sandre * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21122702Sandre * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22122702Sandre * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23122702Sandre * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24122702Sandre * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25122702Sandre * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26122702Sandre * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27122702Sandre * SUCH DAMAGE. 28122702Sandre */ 29122702Sandre 30122702Sandre/* 31122702Sandre * ip_fastforward gets its speed from processing the forwarded packet to 32122702Sandre * completion (if_output on the other side) without any queues or netisr's. 33122702Sandre * The receiving interface DMAs the packet into memory, the upper half of 34122702Sandre * driver calls ip_fastforward, we do our routing table lookup and directly 35148324Skeramida * send it off to the outgoing interface, which DMAs the packet to the 36122702Sandre * network card. The only part of the packet we touch with the CPU is the 37122759Sandre * IP header (unless there are complex firewall rules touching other parts 38122759Sandre * of the packet, but that is up to you). We are essentially limited by bus 39122759Sandre * bandwidth and how fast the network card/driver can set up receives and 40122759Sandre * transmits. 41122702Sandre * 42148324Skeramida * We handle basic errors, IP header errors, checksum errors, 43122702Sandre * destination unreachable, fragmentation and fragmentation needed and 44148324Skeramida * report them via ICMP to the sender. 45122702Sandre * 46122702Sandre * Else if something is not pure IPv4 unicast forwarding we fall back to 47122702Sandre * the normal ip_input processing path. We should only be called from 48122702Sandre * interfaces connected to the outside world. 49122702Sandre * 50122702Sandre * Firewalling is fully supported including divert, ipfw fwd and ipfilter 51122702Sandre * ipnat and address rewrite. 52122702Sandre * 53122702Sandre * IPSEC is not supported if this host is a tunnel broker. IPSEC is 54122702Sandre * supported for connections to/from local host. 55122702Sandre * 56122702Sandre * We try to do the least expensive (in CPU ops) checks and operations 57122702Sandre * first to catch junk with as little overhead as possible. 58122702Sandre * 59148324Skeramida * We take full advantage of hardware support for IP checksum and 60122702Sandre * fragmentation offloading. 61122702Sandre * 62122702Sandre * We don't do ICMP redirect in the fast forwarding path. I have had my own 63122702Sandre * cases where two core routers with Zebra routing suite would send millions 64148324Skeramida * ICMP redirects to connected hosts if the destination router was not the 65148324Skeramida * default gateway. In one case it was filling the routing table of a host 66148324Skeramida * with approximately 300.000 cloned redirect entries until it ran out of 67148324Skeramida * kernel memory. However the networking code proved very robust and it didn't 68148324Skeramida * crash or fail in other ways. 69122702Sandre */ 70122702Sandre 71122702Sandre/* 72122702Sandre * Many thanks to Matt Thomas of NetBSD for basic structure of ip_flow.c which 73122702Sandre * is being followed here. 74122702Sandre */ 75122702Sandre 76172467Ssilby#include <sys/cdefs.h> 77172467Ssilby__FBSDID("$FreeBSD: head/sys/netinet/ip_fastfwd.c 197952 2009-10-11 05:59:43Z julian $"); 78172467Ssilby 79122702Sandre#include "opt_ipfw.h" 80122702Sandre#include "opt_ipstealth.h" 81122702Sandre 82122702Sandre#include <sys/param.h> 83122702Sandre#include <sys/systm.h> 84122702Sandre#include <sys/kernel.h> 85122702Sandre#include <sys/malloc.h> 86122702Sandre#include <sys/mbuf.h> 87122702Sandre#include <sys/protosw.h> 88122702Sandre#include <sys/socket.h> 89122702Sandre#include <sys/sysctl.h> 90122702Sandre 91122702Sandre#include <net/pfil.h> 92122702Sandre#include <net/if.h> 93122702Sandre#include <net/if_types.h> 94122702Sandre#include <net/if_var.h> 95122702Sandre#include <net/if_dl.h> 96122702Sandre#include <net/route.h> 97196019Srwatson#include <net/vnet.h> 98122702Sandre 99122702Sandre#include <netinet/in.h> 100122702Sandre#include <netinet/in_systm.h> 101122702Sandre#include <netinet/in_var.h> 102122702Sandre#include <netinet/ip.h> 103122702Sandre#include <netinet/ip_var.h> 104122702Sandre#include <netinet/ip_icmp.h> 105152592Sandre#include <netinet/ip_options.h> 106122702Sandre 107122702Sandre#include <machine/in_cksum.h> 108122702Sandre 109195699Srwatsonstatic VNET_DEFINE(int, ipfastforward_active); 110195727Srwatson#define V_ipfastforward_active VNET(ipfastforward_active) 111122702Sandre 112195699SrwatsonSYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, fastforwarding, CTLFLAG_RW, 113195699Srwatson &VNET_NAME(ipfastforward_active), 0, "Enable fast IP forwarding"); 114195699Srwatson 115128872Sandrestatic struct sockaddr_in * 116133497Sandreip_findroute(struct route *ro, struct in_addr dest, struct mbuf *m) 117128872Sandre{ 118128872Sandre struct sockaddr_in *dst; 119128872Sandre struct rtentry *rt; 120128872Sandre 121128872Sandre /* 122128872Sandre * Find route to destination. 123128872Sandre */ 124128872Sandre bzero(ro, sizeof(*ro)); 125128872Sandre dst = (struct sockaddr_in *)&ro->ro_dst; 126128872Sandre dst->sin_family = AF_INET; 127128872Sandre dst->sin_len = sizeof(*dst); 128133497Sandre dst->sin_addr.s_addr = dest.s_addr; 129186119Sqingli in_rtalloc_ign(ro, 0, M_GETFIB(m)); 130128872Sandre 131128872Sandre /* 132128872Sandre * Route there and interface still up? 133128872Sandre */ 134128872Sandre rt = ro->ro_rt; 135128872Sandre if (rt && (rt->rt_flags & RTF_UP) && 136128872Sandre (rt->rt_ifp->if_flags & IFF_UP) && 137148887Srwatson (rt->rt_ifp->if_drv_flags & IFF_DRV_RUNNING)) { 138128872Sandre if (rt->rt_flags & RTF_GATEWAY) 139128872Sandre dst = (struct sockaddr_in *)rt->rt_gateway; 140128872Sandre } else { 141190951Srwatson IPSTAT_INC(ips_noroute); 142190951Srwatson IPSTAT_INC(ips_cantforward); 143128872Sandre if (rt) 144128872Sandre RTFREE(rt); 145145863Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 146128872Sandre return NULL; 147128872Sandre } 148128872Sandre return dst; 149128872Sandre} 150128872Sandre 151122702Sandre/* 152122702Sandre * Try to forward a packet based on the destination address. 153122702Sandre * This is a fast path optimized for the plain forwarding case. 154196881Spjd * If the packet is handled (and consumed) here then we return NULL; 155196881Spjd * otherwise mbuf is returned and the packet should be delivered 156122702Sandre * to ip_input for full processing. 157122702Sandre */ 158154518Sandrestruct mbuf * 159122702Sandreip_fastforward(struct mbuf *m) 160122702Sandre{ 161122702Sandre struct ip *ip; 162122702Sandre struct mbuf *m0 = NULL; 163122702Sandre struct route ro; 164122702Sandre struct sockaddr_in *dst = NULL; 165128872Sandre struct ifnet *ifp; 166133497Sandre struct in_addr odest, dest; 167128872Sandre u_short sum, ip_len; 168122702Sandre int error = 0; 169133920Sandre int hlen, mtu; 170133920Sandre#ifdef IPFIREWALL_FORWARD 171133920Sandre struct m_tag *fwd_tag; 172133920Sandre#endif 173122702Sandre 174122702Sandre /* 175122702Sandre * Are we active and forwarding packets? 176122702Sandre */ 177181803Sbz if (!V_ipfastforward_active || !V_ipforwarding) 178154518Sandre return m; 179122702Sandre 180122702Sandre M_ASSERTVALID(m); 181122702Sandre M_ASSERTPKTHDR(m); 182122702Sandre 183191148Skmacy bzero(&ro, sizeof(ro)); 184128872Sandre 185122702Sandre /* 186122702Sandre * Step 1: check for packet drop conditions (and sanity checks) 187122702Sandre */ 188122702Sandre 189122702Sandre /* 190122702Sandre * Is entire packet big enough? 191122702Sandre */ 192122702Sandre if (m->m_pkthdr.len < sizeof(struct ip)) { 193190951Srwatson IPSTAT_INC(ips_tooshort); 194122702Sandre goto drop; 195122702Sandre } 196122702Sandre 197122702Sandre /* 198122702Sandre * Is first mbuf large enough for ip header and is header present? 199122702Sandre */ 200122702Sandre if (m->m_len < sizeof (struct ip) && 201137302Sandre (m = m_pullup(m, sizeof (struct ip))) == NULL) { 202190951Srwatson IPSTAT_INC(ips_toosmall); 203154518Sandre return NULL; /* mbuf already free'd */ 204122702Sandre } 205122702Sandre 206122702Sandre ip = mtod(m, struct ip *); 207122702Sandre 208122702Sandre /* 209122702Sandre * Is it IPv4? 210122702Sandre */ 211122702Sandre if (ip->ip_v != IPVERSION) { 212190951Srwatson IPSTAT_INC(ips_badvers); 213122702Sandre goto drop; 214122702Sandre } 215122702Sandre 216122702Sandre /* 217122702Sandre * Is IP header length correct and is it in first mbuf? 218122702Sandre */ 219122702Sandre hlen = ip->ip_hl << 2; 220122702Sandre if (hlen < sizeof(struct ip)) { /* minimum header length */ 221190951Srwatson IPSTAT_INC(ips_badlen); 222122702Sandre goto drop; 223122702Sandre } 224122702Sandre if (hlen > m->m_len) { 225154518Sandre if ((m = m_pullup(m, hlen)) == NULL) { 226190951Srwatson IPSTAT_INC(ips_badhlen); 227154518Sandre return NULL; /* mbuf already free'd */ 228122702Sandre } 229122702Sandre ip = mtod(m, struct ip *); 230122702Sandre } 231122702Sandre 232122702Sandre /* 233122702Sandre * Checksum correct? 234122702Sandre */ 235122702Sandre if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) 236122702Sandre sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID); 237122702Sandre else { 238122702Sandre if (hlen == sizeof(struct ip)) 239122702Sandre sum = in_cksum_hdr(ip); 240122702Sandre else 241122702Sandre sum = in_cksum(m, hlen); 242122702Sandre } 243122702Sandre if (sum) { 244190951Srwatson IPSTAT_INC(ips_badsum); 245122702Sandre goto drop; 246122702Sandre } 247136690Sandre 248136690Sandre /* 249148324Skeramida * Remember that we have checked the IP header and found it valid. 250136690Sandre */ 251122702Sandre m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID); 252122702Sandre 253128872Sandre ip_len = ntohs(ip->ip_len); 254122702Sandre 255122702Sandre /* 256122702Sandre * Is IP length longer than packet we have got? 257122702Sandre */ 258128872Sandre if (m->m_pkthdr.len < ip_len) { 259190951Srwatson IPSTAT_INC(ips_tooshort); 260122702Sandre goto drop; 261122702Sandre } 262122702Sandre 263122702Sandre /* 264122702Sandre * Is packet longer than IP header tells us? If yes, truncate packet. 265122702Sandre */ 266128872Sandre if (m->m_pkthdr.len > ip_len) { 267122702Sandre if (m->m_len == m->m_pkthdr.len) { 268128872Sandre m->m_len = ip_len; 269128872Sandre m->m_pkthdr.len = ip_len; 270122702Sandre } else 271128872Sandre m_adj(m, ip_len - m->m_pkthdr.len); 272122702Sandre } 273122702Sandre 274122702Sandre /* 275122702Sandre * Is packet from or to 127/8? 276122702Sandre */ 277122702Sandre if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET || 278122702Sandre (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) { 279190951Srwatson IPSTAT_INC(ips_badaddr); 280122702Sandre goto drop; 281122702Sandre } 282122702Sandre 283133480Sandre#ifdef ALTQ 284122702Sandre /* 285133480Sandre * Is packet dropped by traffic conditioner? 286133480Sandre */ 287133480Sandre if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) 288154518Sandre goto drop; 289133480Sandre#endif 290133480Sandre 291133480Sandre /* 292122702Sandre * Step 2: fallback conditions to normal ip_input path processing 293122702Sandre */ 294122702Sandre 295122702Sandre /* 296122702Sandre * Only IP packets without options 297122702Sandre */ 298129017Sandre if (ip->ip_hl != (sizeof(struct ip) >> 2)) { 299129017Sandre if (ip_doopts == 1) 300154518Sandre return m; 301129017Sandre else if (ip_doopts == 2) { 302129017Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_FILTER_PROHIB, 303145863Sandre 0, 0); 304154518Sandre return NULL; /* mbuf already free'd */ 305129017Sandre } 306129017Sandre /* else ignore IP options and continue */ 307129017Sandre } 308122702Sandre 309122702Sandre /* 310122702Sandre * Only unicast IP, not from loopback, no L2 or IP broadcast, 311122702Sandre * no multicast, no INADDR_ANY 312122702Sandre * 313122702Sandre * XXX: Probably some of these checks could be direct drop 314122702Sandre * conditions. However it is not clear whether there are some 315122702Sandre * hacks or obscure behaviours which make it neccessary to 316122702Sandre * let ip_input handle it. We play safe here and let ip_input 317122702Sandre * deal with it until it is proven that we can directly drop it. 318122702Sandre */ 319149369Sandre if ((m->m_flags & (M_BCAST|M_MCAST)) || 320149369Sandre (m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) || 321122702Sandre ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST || 322122702Sandre ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST || 323122702Sandre IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 324122702Sandre IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 325166452Sbms IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) || 326166452Sbms IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr)) || 327149369Sandre ip->ip_src.s_addr == INADDR_ANY || 328122702Sandre ip->ip_dst.s_addr == INADDR_ANY ) 329154518Sandre return m; 330122702Sandre 331122702Sandre /* 332122702Sandre * Is it for a local address on this host? 333122702Sandre */ 334133497Sandre if (in_localip(ip->ip_dst)) 335154518Sandre return m; 336122702Sandre 337190951Srwatson IPSTAT_INC(ips_total); 338122702Sandre 339122702Sandre /* 340122702Sandre * Step 3: incoming packet firewall processing 341122702Sandre */ 342122702Sandre 343128872Sandre /* 344128872Sandre * Convert to host representation 345128872Sandre */ 346128872Sandre ip->ip_len = ntohs(ip->ip_len); 347128872Sandre ip->ip_off = ntohs(ip->ip_off); 348128872Sandre 349133497Sandre odest.s_addr = dest.s_addr = ip->ip_dst.s_addr; 350134383Sandre 351122702Sandre /* 352122702Sandre * Run through list of ipfilter hooks for input packets 353122702Sandre */ 354197952Sjulian if (!PFIL_HOOKED(&V_inet_pfil_hook)) 355134383Sandre goto passin; 356134383Sandre 357197952Sjulian if (pfil_run_hooks( 358197952Sjulian &V_inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN, NULL) || 359122702Sandre m == NULL) 360154518Sandre goto drop; 361122702Sandre 362122702Sandre M_ASSERTVALID(m); 363122702Sandre M_ASSERTPKTHDR(m); 364122702Sandre 365122702Sandre ip = mtod(m, struct ip *); /* m may have changed by pfil hook */ 366133497Sandre dest.s_addr = ip->ip_dst.s_addr; 367122702Sandre 368122702Sandre /* 369122702Sandre * Destination address changed? 370122702Sandre */ 371133497Sandre if (odest.s_addr != dest.s_addr) { 372122702Sandre /* 373122702Sandre * Is it now for a local address on this host? 374122702Sandre */ 375133497Sandre if (in_localip(dest)) 376133497Sandre goto forwardlocal; 377122702Sandre /* 378122702Sandre * Go on with new destination address 379122702Sandre */ 380122702Sandre } 381133920Sandre#ifdef IPFIREWALL_FORWARD 382133920Sandre if (m->m_flags & M_FASTFWD_OURS) { 383133920Sandre /* 384133920Sandre * ipfw changed it for a local address on this host. 385133920Sandre */ 386133920Sandre goto forwardlocal; 387133920Sandre } 388133920Sandre#endif /* IPFIREWALL_FORWARD */ 389122702Sandre 390134383Sandrepassin: 391122702Sandre /* 392122702Sandre * Step 4: decrement TTL and look up route 393122702Sandre */ 394122702Sandre 395122702Sandre /* 396122702Sandre * Check TTL 397122702Sandre */ 398122702Sandre#ifdef IPSTEALTH 399181803Sbz if (!V_ipstealth) { 400122702Sandre#endif 401122702Sandre if (ip->ip_ttl <= IPTTLDEC) { 402145863Sandre icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, 0); 403154518Sandre return NULL; /* mbuf already free'd */ 404122702Sandre } 405122702Sandre 406122702Sandre /* 407136690Sandre * Decrement the TTL and incrementally change the IP header checksum. 408136690Sandre * Don't bother doing this with hw checksum offloading, it's faster 409136690Sandre * doing it right here. 410122702Sandre */ 411122702Sandre ip->ip_ttl -= IPTTLDEC; 412122702Sandre if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 413122702Sandre ip->ip_sum -= ~htons(IPTTLDEC << 8); 414122702Sandre else 415122702Sandre ip->ip_sum += htons(IPTTLDEC << 8); 416122702Sandre#ifdef IPSTEALTH 417122702Sandre } 418122702Sandre#endif 419122702Sandre 420122702Sandre /* 421122702Sandre * Find route to destination. 422122702Sandre */ 423128872Sandre if ((dst = ip_findroute(&ro, dest, m)) == NULL) 424154518Sandre return NULL; /* icmp unreach already sent */ 425128872Sandre ifp = ro.ro_rt->rt_ifp; 426122702Sandre 427122702Sandre /* 428166507Sbms * Immediately drop blackholed traffic, and directed broadcasts 429166507Sbms * for either the all-ones or all-zero subnet addresses on 430166507Sbms * locally attached networks. 431137179Sbms */ 432166507Sbms if ((ro.ro_rt->rt_flags & (RTF_BLACKHOLE|RTF_BROADCAST)) != 0) 433137179Sbms goto drop; 434137179Sbms 435137179Sbms /* 436122702Sandre * Step 5: outgoing firewall packet processing 437122702Sandre */ 438122702Sandre 439122702Sandre /* 440122702Sandre * Run through list of hooks for output packets. 441122702Sandre */ 442197952Sjulian if (!PFIL_HOOKED(&V_inet_pfil_hook)) 443134383Sandre goto passout; 444134383Sandre 445197952Sjulian if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_OUT, NULL) || m == NULL) { 446154518Sandre goto drop; 447122702Sandre } 448122702Sandre 449122702Sandre M_ASSERTVALID(m); 450122702Sandre M_ASSERTPKTHDR(m); 451122702Sandre 452122702Sandre ip = mtod(m, struct ip *); 453133497Sandre dest.s_addr = ip->ip_dst.s_addr; 454122702Sandre 455122702Sandre /* 456122702Sandre * Destination address changed? 457122702Sandre */ 458133920Sandre#ifndef IPFIREWALL_FORWARD 459133497Sandre if (odest.s_addr != dest.s_addr) { 460133920Sandre#else 461133920Sandre fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 462133920Sandre if (odest.s_addr != dest.s_addr || fwd_tag != NULL) { 463133920Sandre#endif /* IPFIREWALL_FORWARD */ 464122702Sandre /* 465122702Sandre * Is it now for a local address on this host? 466122702Sandre */ 467133920Sandre#ifndef IPFIREWALL_FORWARD 468133497Sandre if (in_localip(dest)) { 469133920Sandre#else 470136690Sandre if (m->m_flags & M_FASTFWD_OURS || in_localip(dest)) { 471133920Sandre#endif /* IPFIREWALL_FORWARD */ 472122702Sandreforwardlocal: 473133497Sandre /* 474135158Sandre * Return packet for processing by ip_input(). 475135158Sandre * Keep host byte order as expected at ip_input's 476135158Sandre * "ours"-label. 477133497Sandre */ 478135158Sandre m->m_flags |= M_FASTFWD_OURS; 479133497Sandre if (ro.ro_rt) 480133497Sandre RTFREE(ro.ro_rt); 481154518Sandre return m; 482122702Sandre } 483122702Sandre /* 484122702Sandre * Redo route lookup with new destination address 485122702Sandre */ 486133920Sandre#ifdef IPFIREWALL_FORWARD 487133920Sandre if (fwd_tag) { 488161380Sjulian dest.s_addr = ((struct sockaddr_in *) 489157833Sglebius (fwd_tag + 1))->sin_addr.s_addr; 490133920Sandre m_tag_delete(m, fwd_tag); 491133920Sandre } 492133920Sandre#endif /* IPFIREWALL_FORWARD */ 493122702Sandre RTFREE(ro.ro_rt); 494128872Sandre if ((dst = ip_findroute(&ro, dest, m)) == NULL) 495154518Sandre return NULL; /* icmp unreach already sent */ 496128872Sandre ifp = ro.ro_rt->rt_ifp; 497122702Sandre } 498122702Sandre 499134383Sandrepassout: 500122702Sandre /* 501122702Sandre * Step 6: send off the packet 502122702Sandre */ 503122702Sandre 504122702Sandre /* 505128872Sandre * Check if route is dampned (when ARP is unable to resolve) 506128872Sandre */ 507128872Sandre if ((ro.ro_rt->rt_flags & RTF_REJECT) && 508167682Sbms (ro.ro_rt->rt_rmx.rmx_expire == 0 || 509167682Sbms time_uptime < ro.ro_rt->rt_rmx.rmx_expire)) { 510145863Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 511128872Sandre goto consumed; 512128872Sandre } 513128872Sandre 514133480Sandre#ifndef ALTQ 515128872Sandre /* 516128872Sandre * Check if there is enough space in the interface queue 517128872Sandre */ 518128872Sandre if ((ifp->if_snd.ifq_len + ip->ip_len / ifp->if_mtu + 1) >= 519128872Sandre ifp->if_snd.ifq_maxlen) { 520190951Srwatson IPSTAT_INC(ips_odropped); 521128872Sandre /* would send source quench here but that is depreciated */ 522128872Sandre goto drop; 523128872Sandre } 524133480Sandre#endif 525128872Sandre 526128872Sandre /* 527128872Sandre * Check if media link state of interface is not down 528128872Sandre */ 529128872Sandre if (ifp->if_link_state == LINK_STATE_DOWN) { 530145863Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 531128872Sandre goto consumed; 532128872Sandre } 533128872Sandre 534128872Sandre /* 535148324Skeramida * Check if packet fits MTU or if hardware will fragment for us 536122702Sandre */ 537122702Sandre if (ro.ro_rt->rt_rmx.rmx_mtu) 538122702Sandre mtu = min(ro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 539122702Sandre else 540122702Sandre mtu = ifp->if_mtu; 541122702Sandre 542122702Sandre if (ip->ip_len <= mtu || 543122702Sandre (ifp->if_hwassist & CSUM_FRAGMENT && (ip->ip_off & IP_DF) == 0)) { 544122702Sandre /* 545122702Sandre * Restore packet header fields to original values 546122702Sandre */ 547122702Sandre ip->ip_len = htons(ip->ip_len); 548122702Sandre ip->ip_off = htons(ip->ip_off); 549122702Sandre /* 550122702Sandre * Send off the packet via outgoing interface 551122702Sandre */ 552122702Sandre error = (*ifp->if_output)(ifp, m, 553191148Skmacy (struct sockaddr *)dst, &ro); 554122702Sandre } else { 555122702Sandre /* 556128872Sandre * Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery 557122702Sandre */ 558122702Sandre if (ip->ip_off & IP_DF) { 559190951Srwatson IPSTAT_INC(ips_cantfrag); 560122702Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG, 561145863Sandre 0, mtu); 562128872Sandre goto consumed; 563122702Sandre } else { 564122702Sandre /* 565148324Skeramida * We have to fragment the packet 566122702Sandre */ 567122702Sandre m->m_pkthdr.csum_flags |= CSUM_IP; 568128872Sandre /* 569128872Sandre * ip_fragment expects ip_len and ip_off in host byte 570128872Sandre * order but returns all packets in network byte order 571128872Sandre */ 572122702Sandre if (ip_fragment(ip, &m, mtu, ifp->if_hwassist, 573122702Sandre (~ifp->if_hwassist & CSUM_DELAY_IP))) { 574122702Sandre goto drop; 575122702Sandre } 576122702Sandre KASSERT(m != NULL, ("null mbuf and no error")); 577122702Sandre /* 578122702Sandre * Send off the fragments via outgoing interface 579122702Sandre */ 580122702Sandre error = 0; 581122702Sandre do { 582122702Sandre m0 = m->m_nextpkt; 583122702Sandre m->m_nextpkt = NULL; 584122702Sandre 585122702Sandre error = (*ifp->if_output)(ifp, m, 586191148Skmacy (struct sockaddr *)dst, &ro); 587122702Sandre if (error) 588122702Sandre break; 589122702Sandre } while ((m = m0) != NULL); 590122702Sandre if (error) { 591122702Sandre /* Reclaim remaining fragments */ 592144301Sglebius for (m = m0; m; m = m0) { 593122702Sandre m0 = m->m_nextpkt; 594122702Sandre m_freem(m); 595122702Sandre } 596122702Sandre } else 597190951Srwatson IPSTAT_INC(ips_fragmented); 598122702Sandre } 599122702Sandre } 600122702Sandre 601122702Sandre if (error != 0) 602190951Srwatson IPSTAT_INC(ips_odropped); 603122702Sandre else { 604122702Sandre ro.ro_rt->rt_rmx.rmx_pksent++; 605190951Srwatson IPSTAT_INC(ips_forward); 606190951Srwatson IPSTAT_INC(ips_fastforward); 607122702Sandre } 608128872Sandreconsumed: 609122702Sandre RTFREE(ro.ro_rt); 610154518Sandre return NULL; 611122702Sandredrop: 612122702Sandre if (m) 613122702Sandre m_freem(m); 614128872Sandre if (ro.ro_rt) 615128872Sandre RTFREE(ro.ro_rt); 616154518Sandre return NULL; 617122702Sandre} 618