ip_fastfwd.c revision 190951
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 190951 2009-04-11 23:35:20Z rwatson $"); 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> 90181803Sbz#include <sys/vimage.h> 91122702Sandre 92122702Sandre#include <net/pfil.h> 93122702Sandre#include <net/if.h> 94122702Sandre#include <net/if_types.h> 95122702Sandre#include <net/if_var.h> 96122702Sandre#include <net/if_dl.h> 97122702Sandre#include <net/route.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> 106185571Sbz#include <netinet/vinet.h> 107122702Sandre 108122702Sandre#include <machine/in_cksum.h> 109122702Sandre 110185088Szec#ifdef VIMAGE_GLOBALS 111185088Szecstatic int ipfastforward_active; 112185088Szec#endif 113183550SzecSYSCTL_V_INT(V_NET, vnet_inet, _net_inet_ip, OID_AUTO, fastforwarding, 114183550Szec CTLFLAG_RW, ipfastforward_active, 0, "Enable fast IP forwarding"); 115122702Sandre 116128872Sandrestatic struct sockaddr_in * 117133497Sandreip_findroute(struct route *ro, struct in_addr dest, struct mbuf *m) 118128872Sandre{ 119183550Szec INIT_VNET_INET(curvnet); 120128872Sandre struct sockaddr_in *dst; 121128872Sandre struct rtentry *rt; 122128872Sandre 123128872Sandre /* 124128872Sandre * Find route to destination. 125128872Sandre */ 126128872Sandre bzero(ro, sizeof(*ro)); 127128872Sandre dst = (struct sockaddr_in *)&ro->ro_dst; 128128872Sandre dst->sin_family = AF_INET; 129128872Sandre dst->sin_len = sizeof(*dst); 130133497Sandre dst->sin_addr.s_addr = dest.s_addr; 131186119Sqingli in_rtalloc_ign(ro, 0, M_GETFIB(m)); 132128872Sandre 133128872Sandre /* 134128872Sandre * Route there and interface still up? 135128872Sandre */ 136128872Sandre rt = ro->ro_rt; 137128872Sandre if (rt && (rt->rt_flags & RTF_UP) && 138128872Sandre (rt->rt_ifp->if_flags & IFF_UP) && 139148887Srwatson (rt->rt_ifp->if_drv_flags & IFF_DRV_RUNNING)) { 140128872Sandre if (rt->rt_flags & RTF_GATEWAY) 141128872Sandre dst = (struct sockaddr_in *)rt->rt_gateway; 142128872Sandre } else { 143190951Srwatson IPSTAT_INC(ips_noroute); 144190951Srwatson IPSTAT_INC(ips_cantforward); 145128872Sandre if (rt) 146128872Sandre RTFREE(rt); 147145863Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 148128872Sandre return NULL; 149128872Sandre } 150128872Sandre return dst; 151128872Sandre} 152128872Sandre 153122702Sandre/* 154122702Sandre * Try to forward a packet based on the destination address. 155122702Sandre * This is a fast path optimized for the plain forwarding case. 156122702Sandre * If the packet is handled (and consumed) here then we return 1; 157122702Sandre * otherwise 0 is returned and the packet should be delivered 158122702Sandre * to ip_input for full processing. 159122702Sandre */ 160154518Sandrestruct mbuf * 161122702Sandreip_fastforward(struct mbuf *m) 162122702Sandre{ 163183550Szec INIT_VNET_INET(curvnet); 164122702Sandre struct ip *ip; 165122702Sandre struct mbuf *m0 = NULL; 166122702Sandre struct route ro; 167122702Sandre struct sockaddr_in *dst = NULL; 168128872Sandre struct ifnet *ifp; 169133497Sandre struct in_addr odest, dest; 170128872Sandre u_short sum, ip_len; 171122702Sandre int error = 0; 172133920Sandre int hlen, mtu; 173133920Sandre#ifdef IPFIREWALL_FORWARD 174133920Sandre struct m_tag *fwd_tag; 175133920Sandre#endif 176122702Sandre 177122702Sandre /* 178122702Sandre * Are we active and forwarding packets? 179122702Sandre */ 180181803Sbz if (!V_ipfastforward_active || !V_ipforwarding) 181154518Sandre return m; 182122702Sandre 183122702Sandre M_ASSERTVALID(m); 184122702Sandre M_ASSERTPKTHDR(m); 185122702Sandre 186128872Sandre ro.ro_rt = NULL; 187128872Sandre 188122702Sandre /* 189122702Sandre * Step 1: check for packet drop conditions (and sanity checks) 190122702Sandre */ 191122702Sandre 192122702Sandre /* 193122702Sandre * Is entire packet big enough? 194122702Sandre */ 195122702Sandre if (m->m_pkthdr.len < sizeof(struct ip)) { 196190951Srwatson IPSTAT_INC(ips_tooshort); 197122702Sandre goto drop; 198122702Sandre } 199122702Sandre 200122702Sandre /* 201122702Sandre * Is first mbuf large enough for ip header and is header present? 202122702Sandre */ 203122702Sandre if (m->m_len < sizeof (struct ip) && 204137302Sandre (m = m_pullup(m, sizeof (struct ip))) == NULL) { 205190951Srwatson IPSTAT_INC(ips_toosmall); 206154518Sandre return NULL; /* mbuf already free'd */ 207122702Sandre } 208122702Sandre 209122702Sandre ip = mtod(m, struct ip *); 210122702Sandre 211122702Sandre /* 212122702Sandre * Is it IPv4? 213122702Sandre */ 214122702Sandre if (ip->ip_v != IPVERSION) { 215190951Srwatson IPSTAT_INC(ips_badvers); 216122702Sandre goto drop; 217122702Sandre } 218122702Sandre 219122702Sandre /* 220122702Sandre * Is IP header length correct and is it in first mbuf? 221122702Sandre */ 222122702Sandre hlen = ip->ip_hl << 2; 223122702Sandre if (hlen < sizeof(struct ip)) { /* minimum header length */ 224190951Srwatson IPSTAT_INC(ips_badlen); 225122702Sandre goto drop; 226122702Sandre } 227122702Sandre if (hlen > m->m_len) { 228154518Sandre if ((m = m_pullup(m, hlen)) == NULL) { 229190951Srwatson IPSTAT_INC(ips_badhlen); 230154518Sandre return NULL; /* mbuf already free'd */ 231122702Sandre } 232122702Sandre ip = mtod(m, struct ip *); 233122702Sandre } 234122702Sandre 235122702Sandre /* 236122702Sandre * Checksum correct? 237122702Sandre */ 238122702Sandre if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) 239122702Sandre sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID); 240122702Sandre else { 241122702Sandre if (hlen == sizeof(struct ip)) 242122702Sandre sum = in_cksum_hdr(ip); 243122702Sandre else 244122702Sandre sum = in_cksum(m, hlen); 245122702Sandre } 246122702Sandre if (sum) { 247190951Srwatson IPSTAT_INC(ips_badsum); 248122702Sandre goto drop; 249122702Sandre } 250136690Sandre 251136690Sandre /* 252148324Skeramida * Remember that we have checked the IP header and found it valid. 253136690Sandre */ 254122702Sandre m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID); 255122702Sandre 256128872Sandre ip_len = ntohs(ip->ip_len); 257122702Sandre 258122702Sandre /* 259122702Sandre * Is IP length longer than packet we have got? 260122702Sandre */ 261128872Sandre if (m->m_pkthdr.len < ip_len) { 262190951Srwatson IPSTAT_INC(ips_tooshort); 263122702Sandre goto drop; 264122702Sandre } 265122702Sandre 266122702Sandre /* 267122702Sandre * Is packet longer than IP header tells us? If yes, truncate packet. 268122702Sandre */ 269128872Sandre if (m->m_pkthdr.len > ip_len) { 270122702Sandre if (m->m_len == m->m_pkthdr.len) { 271128872Sandre m->m_len = ip_len; 272128872Sandre m->m_pkthdr.len = ip_len; 273122702Sandre } else 274128872Sandre m_adj(m, ip_len - m->m_pkthdr.len); 275122702Sandre } 276122702Sandre 277122702Sandre /* 278122702Sandre * Is packet from or to 127/8? 279122702Sandre */ 280122702Sandre if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET || 281122702Sandre (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) { 282190951Srwatson IPSTAT_INC(ips_badaddr); 283122702Sandre goto drop; 284122702Sandre } 285122702Sandre 286133480Sandre#ifdef ALTQ 287122702Sandre /* 288133480Sandre * Is packet dropped by traffic conditioner? 289133480Sandre */ 290133480Sandre if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) 291154518Sandre goto drop; 292133480Sandre#endif 293133480Sandre 294133480Sandre /* 295122702Sandre * Step 2: fallback conditions to normal ip_input path processing 296122702Sandre */ 297122702Sandre 298122702Sandre /* 299122702Sandre * Only IP packets without options 300122702Sandre */ 301129017Sandre if (ip->ip_hl != (sizeof(struct ip) >> 2)) { 302129017Sandre if (ip_doopts == 1) 303154518Sandre return m; 304129017Sandre else if (ip_doopts == 2) { 305129017Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_FILTER_PROHIB, 306145863Sandre 0, 0); 307154518Sandre return NULL; /* mbuf already free'd */ 308129017Sandre } 309129017Sandre /* else ignore IP options and continue */ 310129017Sandre } 311122702Sandre 312122702Sandre /* 313122702Sandre * Only unicast IP, not from loopback, no L2 or IP broadcast, 314122702Sandre * no multicast, no INADDR_ANY 315122702Sandre * 316122702Sandre * XXX: Probably some of these checks could be direct drop 317122702Sandre * conditions. However it is not clear whether there are some 318122702Sandre * hacks or obscure behaviours which make it neccessary to 319122702Sandre * let ip_input handle it. We play safe here and let ip_input 320122702Sandre * deal with it until it is proven that we can directly drop it. 321122702Sandre */ 322149369Sandre if ((m->m_flags & (M_BCAST|M_MCAST)) || 323149369Sandre (m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) || 324122702Sandre ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST || 325122702Sandre ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST || 326122702Sandre IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 327122702Sandre IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 328166452Sbms IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) || 329166452Sbms IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr)) || 330149369Sandre ip->ip_src.s_addr == INADDR_ANY || 331122702Sandre ip->ip_dst.s_addr == INADDR_ANY ) 332154518Sandre return m; 333122702Sandre 334122702Sandre /* 335122702Sandre * Is it for a local address on this host? 336122702Sandre */ 337133497Sandre if (in_localip(ip->ip_dst)) 338154518Sandre return m; 339122702Sandre 340190951Srwatson IPSTAT_INC(ips_total); 341122702Sandre 342122702Sandre /* 343122702Sandre * Step 3: incoming packet firewall processing 344122702Sandre */ 345122702Sandre 346128872Sandre /* 347128872Sandre * Convert to host representation 348128872Sandre */ 349128872Sandre ip->ip_len = ntohs(ip->ip_len); 350128872Sandre ip->ip_off = ntohs(ip->ip_off); 351128872Sandre 352133497Sandre odest.s_addr = dest.s_addr = ip->ip_dst.s_addr; 353134383Sandre 354122702Sandre /* 355122702Sandre * Run through list of ipfilter hooks for input packets 356122702Sandre */ 357155201Scsjp if (!PFIL_HOOKED(&inet_pfil_hook)) 358134383Sandre goto passin; 359134383Sandre 360135920Smlaier if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN, NULL) || 361122702Sandre m == NULL) 362154518Sandre goto drop; 363122702Sandre 364122702Sandre M_ASSERTVALID(m); 365122702Sandre M_ASSERTPKTHDR(m); 366122702Sandre 367122702Sandre ip = mtod(m, struct ip *); /* m may have changed by pfil hook */ 368133497Sandre dest.s_addr = ip->ip_dst.s_addr; 369122702Sandre 370122702Sandre /* 371122702Sandre * Destination address changed? 372122702Sandre */ 373133497Sandre if (odest.s_addr != dest.s_addr) { 374122702Sandre /* 375122702Sandre * Is it now for a local address on this host? 376122702Sandre */ 377133497Sandre if (in_localip(dest)) 378133497Sandre goto forwardlocal; 379122702Sandre /* 380122702Sandre * Go on with new destination address 381122702Sandre */ 382122702Sandre } 383133920Sandre#ifdef IPFIREWALL_FORWARD 384133920Sandre if (m->m_flags & M_FASTFWD_OURS) { 385133920Sandre /* 386133920Sandre * ipfw changed it for a local address on this host. 387133920Sandre */ 388133920Sandre goto forwardlocal; 389133920Sandre } 390133920Sandre#endif /* IPFIREWALL_FORWARD */ 391122702Sandre 392134383Sandrepassin: 393122702Sandre /* 394122702Sandre * Step 4: decrement TTL and look up route 395122702Sandre */ 396122702Sandre 397122702Sandre /* 398122702Sandre * Check TTL 399122702Sandre */ 400122702Sandre#ifdef IPSTEALTH 401181803Sbz if (!V_ipstealth) { 402122702Sandre#endif 403122702Sandre if (ip->ip_ttl <= IPTTLDEC) { 404145863Sandre icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, 0); 405154518Sandre return NULL; /* mbuf already free'd */ 406122702Sandre } 407122702Sandre 408122702Sandre /* 409136690Sandre * Decrement the TTL and incrementally change the IP header checksum. 410136690Sandre * Don't bother doing this with hw checksum offloading, it's faster 411136690Sandre * doing it right here. 412122702Sandre */ 413122702Sandre ip->ip_ttl -= IPTTLDEC; 414122702Sandre if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 415122702Sandre ip->ip_sum -= ~htons(IPTTLDEC << 8); 416122702Sandre else 417122702Sandre ip->ip_sum += htons(IPTTLDEC << 8); 418122702Sandre#ifdef IPSTEALTH 419122702Sandre } 420122702Sandre#endif 421122702Sandre 422122702Sandre /* 423122702Sandre * Find route to destination. 424122702Sandre */ 425128872Sandre if ((dst = ip_findroute(&ro, dest, m)) == NULL) 426154518Sandre return NULL; /* icmp unreach already sent */ 427128872Sandre ifp = ro.ro_rt->rt_ifp; 428122702Sandre 429122702Sandre /* 430166507Sbms * Immediately drop blackholed traffic, and directed broadcasts 431166507Sbms * for either the all-ones or all-zero subnet addresses on 432166507Sbms * locally attached networks. 433137179Sbms */ 434166507Sbms if ((ro.ro_rt->rt_flags & (RTF_BLACKHOLE|RTF_BROADCAST)) != 0) 435137179Sbms goto drop; 436137179Sbms 437137179Sbms /* 438122702Sandre * Step 5: outgoing firewall packet processing 439122702Sandre */ 440122702Sandre 441122702Sandre /* 442122702Sandre * Run through list of hooks for output packets. 443122702Sandre */ 444155201Scsjp if (!PFIL_HOOKED(&inet_pfil_hook)) 445134383Sandre goto passout; 446134383Sandre 447135920Smlaier if (pfil_run_hooks(&inet_pfil_hook, &m, ifp, PFIL_OUT, NULL) || m == NULL) { 448154518Sandre goto drop; 449122702Sandre } 450122702Sandre 451122702Sandre M_ASSERTVALID(m); 452122702Sandre M_ASSERTPKTHDR(m); 453122702Sandre 454122702Sandre ip = mtod(m, struct ip *); 455133497Sandre dest.s_addr = ip->ip_dst.s_addr; 456122702Sandre 457122702Sandre /* 458122702Sandre * Destination address changed? 459122702Sandre */ 460133920Sandre#ifndef IPFIREWALL_FORWARD 461133497Sandre if (odest.s_addr != dest.s_addr) { 462133920Sandre#else 463133920Sandre fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 464133920Sandre if (odest.s_addr != dest.s_addr || fwd_tag != NULL) { 465133920Sandre#endif /* IPFIREWALL_FORWARD */ 466122702Sandre /* 467122702Sandre * Is it now for a local address on this host? 468122702Sandre */ 469133920Sandre#ifndef IPFIREWALL_FORWARD 470133497Sandre if (in_localip(dest)) { 471133920Sandre#else 472136690Sandre if (m->m_flags & M_FASTFWD_OURS || in_localip(dest)) { 473133920Sandre#endif /* IPFIREWALL_FORWARD */ 474122702Sandreforwardlocal: 475133497Sandre /* 476135158Sandre * Return packet for processing by ip_input(). 477135158Sandre * Keep host byte order as expected at ip_input's 478135158Sandre * "ours"-label. 479133497Sandre */ 480135158Sandre m->m_flags |= M_FASTFWD_OURS; 481133497Sandre if (ro.ro_rt) 482133497Sandre RTFREE(ro.ro_rt); 483154518Sandre return m; 484122702Sandre } 485122702Sandre /* 486122702Sandre * Redo route lookup with new destination address 487122702Sandre */ 488133920Sandre#ifdef IPFIREWALL_FORWARD 489133920Sandre if (fwd_tag) { 490161380Sjulian dest.s_addr = ((struct sockaddr_in *) 491157833Sglebius (fwd_tag + 1))->sin_addr.s_addr; 492133920Sandre m_tag_delete(m, fwd_tag); 493133920Sandre } 494133920Sandre#endif /* IPFIREWALL_FORWARD */ 495122702Sandre RTFREE(ro.ro_rt); 496128872Sandre if ((dst = ip_findroute(&ro, dest, m)) == NULL) 497154518Sandre return NULL; /* icmp unreach already sent */ 498128872Sandre ifp = ro.ro_rt->rt_ifp; 499122702Sandre } 500122702Sandre 501134383Sandrepassout: 502122702Sandre /* 503122702Sandre * Step 6: send off the packet 504122702Sandre */ 505122702Sandre 506122702Sandre /* 507128872Sandre * Check if route is dampned (when ARP is unable to resolve) 508128872Sandre */ 509128872Sandre if ((ro.ro_rt->rt_flags & RTF_REJECT) && 510167682Sbms (ro.ro_rt->rt_rmx.rmx_expire == 0 || 511167682Sbms time_uptime < ro.ro_rt->rt_rmx.rmx_expire)) { 512145863Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 513128872Sandre goto consumed; 514128872Sandre } 515128872Sandre 516133480Sandre#ifndef ALTQ 517128872Sandre /* 518128872Sandre * Check if there is enough space in the interface queue 519128872Sandre */ 520128872Sandre if ((ifp->if_snd.ifq_len + ip->ip_len / ifp->if_mtu + 1) >= 521128872Sandre ifp->if_snd.ifq_maxlen) { 522190951Srwatson IPSTAT_INC(ips_odropped); 523128872Sandre /* would send source quench here but that is depreciated */ 524128872Sandre goto drop; 525128872Sandre } 526133480Sandre#endif 527128872Sandre 528128872Sandre /* 529128872Sandre * Check if media link state of interface is not down 530128872Sandre */ 531128872Sandre if (ifp->if_link_state == LINK_STATE_DOWN) { 532145863Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 533128872Sandre goto consumed; 534128872Sandre } 535128872Sandre 536128872Sandre /* 537148324Skeramida * Check if packet fits MTU or if hardware will fragment for us 538122702Sandre */ 539122702Sandre if (ro.ro_rt->rt_rmx.rmx_mtu) 540122702Sandre mtu = min(ro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 541122702Sandre else 542122702Sandre mtu = ifp->if_mtu; 543122702Sandre 544122702Sandre if (ip->ip_len <= mtu || 545122702Sandre (ifp->if_hwassist & CSUM_FRAGMENT && (ip->ip_off & IP_DF) == 0)) { 546122702Sandre /* 547122702Sandre * Restore packet header fields to original values 548122702Sandre */ 549122702Sandre ip->ip_len = htons(ip->ip_len); 550122702Sandre ip->ip_off = htons(ip->ip_off); 551122702Sandre /* 552122702Sandre * Send off the packet via outgoing interface 553122702Sandre */ 554122702Sandre error = (*ifp->if_output)(ifp, m, 555122702Sandre (struct sockaddr *)dst, ro.ro_rt); 556122702Sandre } else { 557122702Sandre /* 558128872Sandre * Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery 559122702Sandre */ 560122702Sandre if (ip->ip_off & IP_DF) { 561190951Srwatson IPSTAT_INC(ips_cantfrag); 562122702Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG, 563145863Sandre 0, mtu); 564128872Sandre goto consumed; 565122702Sandre } else { 566122702Sandre /* 567148324Skeramida * We have to fragment the packet 568122702Sandre */ 569122702Sandre m->m_pkthdr.csum_flags |= CSUM_IP; 570128872Sandre /* 571128872Sandre * ip_fragment expects ip_len and ip_off in host byte 572128872Sandre * order but returns all packets in network byte order 573128872Sandre */ 574122702Sandre if (ip_fragment(ip, &m, mtu, ifp->if_hwassist, 575122702Sandre (~ifp->if_hwassist & CSUM_DELAY_IP))) { 576122702Sandre goto drop; 577122702Sandre } 578122702Sandre KASSERT(m != NULL, ("null mbuf and no error")); 579122702Sandre /* 580122702Sandre * Send off the fragments via outgoing interface 581122702Sandre */ 582122702Sandre error = 0; 583122702Sandre do { 584122702Sandre m0 = m->m_nextpkt; 585122702Sandre m->m_nextpkt = NULL; 586122702Sandre 587122702Sandre error = (*ifp->if_output)(ifp, m, 588122702Sandre (struct sockaddr *)dst, ro.ro_rt); 589122702Sandre if (error) 590122702Sandre break; 591122702Sandre } while ((m = m0) != NULL); 592122702Sandre if (error) { 593122702Sandre /* Reclaim remaining fragments */ 594144301Sglebius for (m = m0; m; m = m0) { 595122702Sandre m0 = m->m_nextpkt; 596122702Sandre m_freem(m); 597122702Sandre } 598122702Sandre } else 599190951Srwatson IPSTAT_INC(ips_fragmented); 600122702Sandre } 601122702Sandre } 602122702Sandre 603122702Sandre if (error != 0) 604190951Srwatson IPSTAT_INC(ips_odropped); 605122702Sandre else { 606122702Sandre ro.ro_rt->rt_rmx.rmx_pksent++; 607190951Srwatson IPSTAT_INC(ips_forward); 608190951Srwatson IPSTAT_INC(ips_fastforward); 609122702Sandre } 610128872Sandreconsumed: 611122702Sandre RTFREE(ro.ro_rt); 612154518Sandre return NULL; 613122702Sandredrop: 614122702Sandre if (m) 615122702Sandre m_freem(m); 616128872Sandre if (ro.ro_rt) 617128872Sandre RTFREE(ro.ro_rt); 618154518Sandre return NULL; 619122702Sandre} 620