ip_fastfwd.c revision 242161
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 242161 2012-10-26 21:06:33Z glebius $"); 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 109215701Sdimstatic 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; 167241245Sglebius uint16_t sum, ip_len, ip_off; 168122702Sandre int error = 0; 169133920Sandre int hlen, mtu; 170242079Sae struct m_tag *fwd_tag = NULL; 171122702Sandre 172122702Sandre /* 173122702Sandre * Are we active and forwarding packets? 174122702Sandre */ 175181803Sbz if (!V_ipfastforward_active || !V_ipforwarding) 176154518Sandre return m; 177122702Sandre 178122702Sandre M_ASSERTVALID(m); 179122702Sandre M_ASSERTPKTHDR(m); 180122702Sandre 181191148Skmacy bzero(&ro, sizeof(ro)); 182128872Sandre 183122702Sandre /* 184122702Sandre * Step 1: check for packet drop conditions (and sanity checks) 185122702Sandre */ 186122702Sandre 187122702Sandre /* 188122702Sandre * Is entire packet big enough? 189122702Sandre */ 190122702Sandre if (m->m_pkthdr.len < sizeof(struct ip)) { 191190951Srwatson IPSTAT_INC(ips_tooshort); 192122702Sandre goto drop; 193122702Sandre } 194122702Sandre 195122702Sandre /* 196122702Sandre * Is first mbuf large enough for ip header and is header present? 197122702Sandre */ 198122702Sandre if (m->m_len < sizeof (struct ip) && 199137302Sandre (m = m_pullup(m, sizeof (struct ip))) == NULL) { 200190951Srwatson IPSTAT_INC(ips_toosmall); 201154518Sandre return NULL; /* mbuf already free'd */ 202122702Sandre } 203122702Sandre 204122702Sandre ip = mtod(m, struct ip *); 205122702Sandre 206122702Sandre /* 207122702Sandre * Is it IPv4? 208122702Sandre */ 209122702Sandre if (ip->ip_v != IPVERSION) { 210190951Srwatson IPSTAT_INC(ips_badvers); 211122702Sandre goto drop; 212122702Sandre } 213122702Sandre 214122702Sandre /* 215122702Sandre * Is IP header length correct and is it in first mbuf? 216122702Sandre */ 217122702Sandre hlen = ip->ip_hl << 2; 218122702Sandre if (hlen < sizeof(struct ip)) { /* minimum header length */ 219216192Sbz IPSTAT_INC(ips_badhlen); 220122702Sandre goto drop; 221122702Sandre } 222122702Sandre if (hlen > m->m_len) { 223154518Sandre if ((m = m_pullup(m, hlen)) == NULL) { 224190951Srwatson IPSTAT_INC(ips_badhlen); 225154518Sandre return NULL; /* mbuf already free'd */ 226122702Sandre } 227122702Sandre ip = mtod(m, struct ip *); 228122702Sandre } 229122702Sandre 230122702Sandre /* 231122702Sandre * Checksum correct? 232122702Sandre */ 233122702Sandre if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) 234122702Sandre sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID); 235122702Sandre else { 236122702Sandre if (hlen == sizeof(struct ip)) 237122702Sandre sum = in_cksum_hdr(ip); 238122702Sandre else 239122702Sandre sum = in_cksum(m, hlen); 240122702Sandre } 241122702Sandre if (sum) { 242190951Srwatson IPSTAT_INC(ips_badsum); 243122702Sandre goto drop; 244122702Sandre } 245136690Sandre 246136690Sandre /* 247148324Skeramida * Remember that we have checked the IP header and found it valid. 248136690Sandre */ 249122702Sandre m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID); 250122702Sandre 251128872Sandre ip_len = ntohs(ip->ip_len); 252122702Sandre 253122702Sandre /* 254122702Sandre * Is IP length longer than packet we have got? 255122702Sandre */ 256128872Sandre if (m->m_pkthdr.len < ip_len) { 257190951Srwatson IPSTAT_INC(ips_tooshort); 258122702Sandre goto drop; 259122702Sandre } 260122702Sandre 261122702Sandre /* 262122702Sandre * Is packet longer than IP header tells us? If yes, truncate packet. 263122702Sandre */ 264128872Sandre if (m->m_pkthdr.len > ip_len) { 265122702Sandre if (m->m_len == m->m_pkthdr.len) { 266128872Sandre m->m_len = ip_len; 267128872Sandre m->m_pkthdr.len = ip_len; 268122702Sandre } else 269128872Sandre m_adj(m, ip_len - m->m_pkthdr.len); 270122702Sandre } 271122702Sandre 272122702Sandre /* 273122702Sandre * Is packet from or to 127/8? 274122702Sandre */ 275122702Sandre if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET || 276122702Sandre (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) { 277190951Srwatson IPSTAT_INC(ips_badaddr); 278122702Sandre goto drop; 279122702Sandre } 280122702Sandre 281133480Sandre#ifdef ALTQ 282122702Sandre /* 283133480Sandre * Is packet dropped by traffic conditioner? 284133480Sandre */ 285133480Sandre if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) 286154518Sandre goto drop; 287133480Sandre#endif 288133480Sandre 289133480Sandre /* 290122702Sandre * Step 2: fallback conditions to normal ip_input path processing 291122702Sandre */ 292122702Sandre 293122702Sandre /* 294122702Sandre * Only IP packets without options 295122702Sandre */ 296129017Sandre if (ip->ip_hl != (sizeof(struct ip) >> 2)) { 297129017Sandre if (ip_doopts == 1) 298154518Sandre return m; 299129017Sandre else if (ip_doopts == 2) { 300129017Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_FILTER_PROHIB, 301145863Sandre 0, 0); 302154518Sandre return NULL; /* mbuf already free'd */ 303129017Sandre } 304129017Sandre /* else ignore IP options and continue */ 305129017Sandre } 306122702Sandre 307122702Sandre /* 308122702Sandre * Only unicast IP, not from loopback, no L2 or IP broadcast, 309122702Sandre * no multicast, no INADDR_ANY 310122702Sandre * 311122702Sandre * XXX: Probably some of these checks could be direct drop 312122702Sandre * conditions. However it is not clear whether there are some 313122702Sandre * hacks or obscure behaviours which make it neccessary to 314122702Sandre * let ip_input handle it. We play safe here and let ip_input 315122702Sandre * deal with it until it is proven that we can directly drop it. 316122702Sandre */ 317149369Sandre if ((m->m_flags & (M_BCAST|M_MCAST)) || 318149369Sandre (m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) || 319122702Sandre ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST || 320122702Sandre ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST || 321122702Sandre IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 322122702Sandre IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 323166452Sbms IN_LINKLOCAL(ntohl(ip->ip_src.s_addr)) || 324166452Sbms IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr)) || 325149369Sandre ip->ip_src.s_addr == INADDR_ANY || 326122702Sandre ip->ip_dst.s_addr == INADDR_ANY ) 327154518Sandre return m; 328122702Sandre 329122702Sandre /* 330122702Sandre * Is it for a local address on this host? 331122702Sandre */ 332133497Sandre if (in_localip(ip->ip_dst)) 333154518Sandre return m; 334122702Sandre 335190951Srwatson IPSTAT_INC(ips_total); 336122702Sandre 337122702Sandre /* 338122702Sandre * Step 3: incoming packet firewall processing 339122702Sandre */ 340122702Sandre 341133497Sandre odest.s_addr = dest.s_addr = ip->ip_dst.s_addr; 342134383Sandre 343122702Sandre /* 344122702Sandre * Run through list of ipfilter hooks for input packets 345122702Sandre */ 346197952Sjulian if (!PFIL_HOOKED(&V_inet_pfil_hook)) 347134383Sandre goto passin; 348134383Sandre 349197952Sjulian if (pfil_run_hooks( 350197952Sjulian &V_inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN, NULL) || 351122702Sandre m == NULL) 352154518Sandre goto drop; 353122702Sandre 354122702Sandre M_ASSERTVALID(m); 355122702Sandre M_ASSERTPKTHDR(m); 356122702Sandre 357122702Sandre ip = mtod(m, struct ip *); /* m may have changed by pfil hook */ 358133497Sandre dest.s_addr = ip->ip_dst.s_addr; 359122702Sandre 360122702Sandre /* 361122702Sandre * Destination address changed? 362122702Sandre */ 363133497Sandre if (odest.s_addr != dest.s_addr) { 364122702Sandre /* 365122702Sandre * Is it now for a local address on this host? 366122702Sandre */ 367133497Sandre if (in_localip(dest)) 368133497Sandre goto forwardlocal; 369122702Sandre /* 370122702Sandre * Go on with new destination address 371122702Sandre */ 372122702Sandre } 373242079Sae 374133920Sandre if (m->m_flags & M_FASTFWD_OURS) { 375133920Sandre /* 376133920Sandre * ipfw changed it for a local address on this host. 377133920Sandre */ 378133920Sandre goto forwardlocal; 379133920Sandre } 380122702Sandre 381134383Sandrepassin: 382122702Sandre /* 383122702Sandre * Step 4: decrement TTL and look up route 384122702Sandre */ 385122702Sandre 386122702Sandre /* 387122702Sandre * Check TTL 388122702Sandre */ 389122702Sandre#ifdef IPSTEALTH 390181803Sbz if (!V_ipstealth) { 391122702Sandre#endif 392122702Sandre if (ip->ip_ttl <= IPTTLDEC) { 393145863Sandre icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, 0); 394154518Sandre return NULL; /* mbuf already free'd */ 395122702Sandre } 396122702Sandre 397122702Sandre /* 398136690Sandre * Decrement the TTL and incrementally change the IP header checksum. 399136690Sandre * Don't bother doing this with hw checksum offloading, it's faster 400136690Sandre * doing it right here. 401122702Sandre */ 402122702Sandre ip->ip_ttl -= IPTTLDEC; 403122702Sandre if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8)) 404122702Sandre ip->ip_sum -= ~htons(IPTTLDEC << 8); 405122702Sandre else 406122702Sandre ip->ip_sum += htons(IPTTLDEC << 8); 407122702Sandre#ifdef IPSTEALTH 408122702Sandre } 409122702Sandre#endif 410122702Sandre 411122702Sandre /* 412122702Sandre * Find route to destination. 413122702Sandre */ 414128872Sandre if ((dst = ip_findroute(&ro, dest, m)) == NULL) 415154518Sandre return NULL; /* icmp unreach already sent */ 416128872Sandre ifp = ro.ro_rt->rt_ifp; 417122702Sandre 418122702Sandre /* 419166507Sbms * Immediately drop blackholed traffic, and directed broadcasts 420166507Sbms * for either the all-ones or all-zero subnet addresses on 421166507Sbms * locally attached networks. 422137179Sbms */ 423166507Sbms if ((ro.ro_rt->rt_flags & (RTF_BLACKHOLE|RTF_BROADCAST)) != 0) 424137179Sbms goto drop; 425137179Sbms 426137179Sbms /* 427122702Sandre * Step 5: outgoing firewall packet processing 428122702Sandre */ 429122702Sandre 430122702Sandre /* 431122702Sandre * Run through list of hooks for output packets. 432122702Sandre */ 433197952Sjulian if (!PFIL_HOOKED(&V_inet_pfil_hook)) 434134383Sandre goto passout; 435134383Sandre 436197952Sjulian if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_OUT, NULL) || m == NULL) { 437154518Sandre goto drop; 438122702Sandre } 439122702Sandre 440122702Sandre M_ASSERTVALID(m); 441122702Sandre M_ASSERTPKTHDR(m); 442122702Sandre 443122702Sandre ip = mtod(m, struct ip *); 444133497Sandre dest.s_addr = ip->ip_dst.s_addr; 445122702Sandre 446122702Sandre /* 447122702Sandre * Destination address changed? 448122702Sandre */ 449242079Sae if (V_pfilforward != 0) 450242079Sae fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 451133920Sandre if (odest.s_addr != dest.s_addr || fwd_tag != NULL) { 452122702Sandre /* 453122702Sandre * Is it now for a local address on this host? 454122702Sandre */ 455136690Sandre if (m->m_flags & M_FASTFWD_OURS || in_localip(dest)) { 456122702Sandreforwardlocal: 457133497Sandre /* 458135158Sandre * Return packet for processing by ip_input(). 459133497Sandre */ 460135158Sandre m->m_flags |= M_FASTFWD_OURS; 461133497Sandre if (ro.ro_rt) 462133497Sandre RTFREE(ro.ro_rt); 463154518Sandre return m; 464122702Sandre } 465122702Sandre /* 466122702Sandre * Redo route lookup with new destination address 467122702Sandre */ 468133920Sandre if (fwd_tag) { 469161380Sjulian dest.s_addr = ((struct sockaddr_in *) 470157833Sglebius (fwd_tag + 1))->sin_addr.s_addr; 471133920Sandre m_tag_delete(m, fwd_tag); 472133920Sandre } 473122702Sandre RTFREE(ro.ro_rt); 474128872Sandre if ((dst = ip_findroute(&ro, dest, m)) == NULL) 475154518Sandre return NULL; /* icmp unreach already sent */ 476128872Sandre ifp = ro.ro_rt->rt_ifp; 477122702Sandre } 478122702Sandre 479134383Sandrepassout: 480122702Sandre /* 481122702Sandre * Step 6: send off the packet 482122702Sandre */ 483241245Sglebius ip_len = ntohs(ip->ip_len); 484241245Sglebius ip_off = ntohs(ip->ip_off); 485122702Sandre 486122702Sandre /* 487128872Sandre * Check if route is dampned (when ARP is unable to resolve) 488128872Sandre */ 489128872Sandre if ((ro.ro_rt->rt_flags & RTF_REJECT) && 490167682Sbms (ro.ro_rt->rt_rmx.rmx_expire == 0 || 491167682Sbms time_uptime < ro.ro_rt->rt_rmx.rmx_expire)) { 492145863Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 493128872Sandre goto consumed; 494128872Sandre } 495128872Sandre 496133480Sandre#ifndef ALTQ 497128872Sandre /* 498128872Sandre * Check if there is enough space in the interface queue 499128872Sandre */ 500241245Sglebius if ((ifp->if_snd.ifq_len + ip_len / ifp->if_mtu + 1) >= 501128872Sandre ifp->if_snd.ifq_maxlen) { 502190951Srwatson IPSTAT_INC(ips_odropped); 503128872Sandre /* would send source quench here but that is depreciated */ 504128872Sandre goto drop; 505128872Sandre } 506133480Sandre#endif 507128872Sandre 508128872Sandre /* 509128872Sandre * Check if media link state of interface is not down 510128872Sandre */ 511128872Sandre if (ifp->if_link_state == LINK_STATE_DOWN) { 512145863Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); 513128872Sandre goto consumed; 514128872Sandre } 515128872Sandre 516128872Sandre /* 517148324Skeramida * Check if packet fits MTU or if hardware will fragment for us 518122702Sandre */ 519122702Sandre if (ro.ro_rt->rt_rmx.rmx_mtu) 520122702Sandre mtu = min(ro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu); 521122702Sandre else 522122702Sandre mtu = ifp->if_mtu; 523122702Sandre 524241245Sglebius if (ip_len <= mtu || 525241245Sglebius (ifp->if_hwassist & CSUM_FRAGMENT && (ip_off & IP_DF) == 0)) { 526122702Sandre /* 527122702Sandre * Send off the packet via outgoing interface 528122702Sandre */ 529122702Sandre error = (*ifp->if_output)(ifp, m, 530191148Skmacy (struct sockaddr *)dst, &ro); 531122702Sandre } else { 532122702Sandre /* 533128872Sandre * Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery 534122702Sandre */ 535241245Sglebius if (ip_off & IP_DF) { 536190951Srwatson IPSTAT_INC(ips_cantfrag); 537122702Sandre icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG, 538145863Sandre 0, mtu); 539128872Sandre goto consumed; 540122702Sandre } else { 541122702Sandre /* 542148324Skeramida * We have to fragment the packet 543122702Sandre */ 544122702Sandre m->m_pkthdr.csum_flags |= CSUM_IP; 545242161Sglebius if (ip_fragment(ip, &m, mtu, ifp->if_hwassist)) 546122702Sandre goto drop; 547122702Sandre KASSERT(m != NULL, ("null mbuf and no error")); 548122702Sandre /* 549122702Sandre * Send off the fragments via outgoing interface 550122702Sandre */ 551122702Sandre error = 0; 552122702Sandre do { 553122702Sandre m0 = m->m_nextpkt; 554122702Sandre m->m_nextpkt = NULL; 555122702Sandre 556122702Sandre error = (*ifp->if_output)(ifp, m, 557191148Skmacy (struct sockaddr *)dst, &ro); 558122702Sandre if (error) 559122702Sandre break; 560122702Sandre } while ((m = m0) != NULL); 561122702Sandre if (error) { 562122702Sandre /* Reclaim remaining fragments */ 563144301Sglebius for (m = m0; m; m = m0) { 564122702Sandre m0 = m->m_nextpkt; 565122702Sandre m_freem(m); 566122702Sandre } 567122702Sandre } else 568190951Srwatson IPSTAT_INC(ips_fragmented); 569122702Sandre } 570122702Sandre } 571122702Sandre 572122702Sandre if (error != 0) 573190951Srwatson IPSTAT_INC(ips_odropped); 574122702Sandre else { 575122702Sandre ro.ro_rt->rt_rmx.rmx_pksent++; 576190951Srwatson IPSTAT_INC(ips_forward); 577190951Srwatson IPSTAT_INC(ips_fastforward); 578122702Sandre } 579128872Sandreconsumed: 580122702Sandre RTFREE(ro.ro_rt); 581154518Sandre return NULL; 582122702Sandredrop: 583122702Sandre if (m) 584122702Sandre m_freem(m); 585128872Sandre if (ro.ro_rt) 586128872Sandre RTFREE(ro.ro_rt); 587154518Sandre return NULL; 588122702Sandre} 589