be7e82e44a
Explained by: bde
807 lines
20 KiB
C
807 lines
20 KiB
C
/*
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* Copyright (c) 2003 Andre Oppermann, Internet Business Solutions AG
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* ip_fastforward gets its speed from processing the forwarded packet to
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* completion (if_output on the other side) without any queues or netisr's.
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* The receiving interface DMAs the packet into memory, the upper half of
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* driver calls ip_fastforward, we do our routing table lookup and directly
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* send it off to the outgoing interface which DMAs the packet to the
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* network card. The only part of the packet we touch with the CPU is the
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* IP header (unless there are complex firewall rules touching other parts
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* of the packet, but that is up to you). We are essentially limited by bus
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* bandwidth and how fast the network card/driver can set up receives and
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* transmits.
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*
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* We handle basic errors, ip header errors, checksum errors,
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* destination unreachable, fragmentation and fragmentation needed and
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* report them via icmp to the sender.
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*
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* Else if something is not pure IPv4 unicast forwarding we fall back to
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* the normal ip_input processing path. We should only be called from
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* interfaces connected to the outside world.
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*
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* Firewalling is fully supported including divert, ipfw fwd and ipfilter
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* ipnat and address rewrite.
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*
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* IPSEC is not supported if this host is a tunnel broker. IPSEC is
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* supported for connections to/from local host.
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*
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* We try to do the least expensive (in CPU ops) checks and operations
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* first to catch junk with as little overhead as possible.
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*
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* We take full advantage of hardware support for ip checksum and
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* fragmentation offloading.
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*
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* We don't do ICMP redirect in the fast forwarding path. I have had my own
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* cases where two core routers with Zebra routing suite would send millions
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* ICMP redirects to connected hosts if the router to dest was not the default
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* gateway. In one case it was filling the routing table of a host with close
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* 300'000 cloned redirect entries until it ran out of kernel memory. However
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* the networking code proved very robust and it didn't crash or went ill
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* otherwise.
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*/
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/*
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* Many thanks to Matt Thomas of NetBSD for basic structure of ip_flow.c which
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* is being followed here.
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*/
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#include "opt_ipfw.h"
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#include "opt_ipdn.h"
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#include "opt_ipdivert.h"
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#include "opt_ipfilter.h"
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#include "opt_ipstealth.h"
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#include "opt_mac.h"
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#include "opt_pfil_hooks.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/mac.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/sysctl.h>
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#include <net/pfil.h>
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#include <net/if.h>
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#include <net/if_types.h>
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#include <net/if_var.h>
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#include <net/if_dl.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/in_var.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip_icmp.h>
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#include <machine/in_cksum.h>
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#include <netinet/ip_fw.h>
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#include <netinet/ip_dummynet.h>
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static int ipfastforward_active = 0;
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SYSCTL_INT(_net_inet_ip, OID_AUTO, fastforwarding, CTLFLAG_RW,
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&ipfastforward_active, 0, "Enable fast IP forwarding");
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/*
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* Try to forward a packet based on the destination address.
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* This is a fast path optimized for the plain forwarding case.
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* If the packet is handled (and consumed) here then we return 1;
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* otherwise 0 is returned and the packet should be delivered
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* to ip_input for full processing.
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*/
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int
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ip_fastforward(struct mbuf *m)
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{
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struct ip *ip;
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struct mbuf *m0 = NULL;
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#ifdef IPDIVERT
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struct ip *tip;
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struct mbuf *teem = NULL;
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#endif
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struct mbuf *tag = NULL;
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struct route ro;
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struct sockaddr_in *dst = NULL;
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struct in_ifaddr *ia = NULL;
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struct ifaddr *ifa = NULL;
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struct ifnet *ifp = NULL;
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struct ip_fw_args args;
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in_addr_t odest, dest;
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u_short sum;
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int error = 0;
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int hlen, ipfw, mtu;
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/*
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* Are we active and forwarding packets?
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*/
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if (!ipfastforward_active || !ipforwarding)
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return 0;
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/*
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* If there is any MT_TAG we fall back to ip_input because we can't
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* handle TAGs here. Should never happen as we get directly called
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* from the if_output routines.
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*/
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if (m->m_type == MT_TAG) {
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KASSERT(0, ("%s: packet with MT_TAG not expected", __func__));
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return 0;
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}
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M_ASSERTVALID(m);
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M_ASSERTPKTHDR(m);
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/*
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* Step 1: check for packet drop conditions (and sanity checks)
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*/
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/*
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* Is entire packet big enough?
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*/
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if (m->m_pkthdr.len < sizeof(struct ip)) {
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ipstat.ips_tooshort++;
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goto drop;
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}
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/*
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* Is first mbuf large enough for ip header and is header present?
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*/
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if (m->m_len < sizeof (struct ip) &&
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(m = m_pullup(m, sizeof (struct ip))) == 0) {
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ipstat.ips_toosmall++;
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goto drop;
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}
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ip = mtod(m, struct ip *);
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/*
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* Is it IPv4?
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*/
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if (ip->ip_v != IPVERSION) {
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ipstat.ips_badvers++;
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goto drop;
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}
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/*
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* Is IP header length correct and is it in first mbuf?
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*/
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hlen = ip->ip_hl << 2;
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if (hlen < sizeof(struct ip)) { /* minimum header length */
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ipstat.ips_badlen++;
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goto drop;
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}
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if (hlen > m->m_len) {
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if ((m = m_pullup(m, hlen)) == 0) {
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ipstat.ips_badhlen++;
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goto drop;
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}
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ip = mtod(m, struct ip *);
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}
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/*
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* Checksum correct?
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*/
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if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED)
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sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
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else {
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if (hlen == sizeof(struct ip))
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sum = in_cksum_hdr(ip);
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else
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sum = in_cksum(m, hlen);
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}
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if (sum) {
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ipstat.ips_badsum++;
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goto drop;
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}
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m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
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/*
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* Convert to host representation
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*/
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ip->ip_len = ntohs(ip->ip_len);
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ip->ip_off = ntohs(ip->ip_off);
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/*
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* Is IP length longer than packet we have got?
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*/
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if (m->m_pkthdr.len < ip->ip_len) {
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ipstat.ips_tooshort++;
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goto drop;
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}
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/*
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* Is packet longer than IP header tells us? If yes, truncate packet.
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*/
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if (m->m_pkthdr.len > ip->ip_len) {
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if (m->m_len == m->m_pkthdr.len) {
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m->m_len = ip->ip_len;
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m->m_pkthdr.len = ip->ip_len;
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} else
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m_adj(m, ip->ip_len - m->m_pkthdr.len);
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}
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/*
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* Is packet from or to 127/8?
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*/
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if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
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(ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
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ipstat.ips_badaddr++;
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goto drop;
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}
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/*
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* Step 2: fallback conditions to normal ip_input path processing
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*/
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/*
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* Only IP packets without options
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*/
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if (ip->ip_hl != (sizeof(struct ip) >> 2))
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goto fallback;
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/*
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* Only unicast IP, not from loopback, no L2 or IP broadcast,
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* no multicast, no INADDR_ANY
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*
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* XXX: Probably some of these checks could be direct drop
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* conditions. However it is not clear whether there are some
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* hacks or obscure behaviours which make it neccessary to
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* let ip_input handle it. We play safe here and let ip_input
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* deal with it until it is proven that we can directly drop it.
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*/
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if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) ||
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ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST ||
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ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST ||
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IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
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IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
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ip->ip_dst.s_addr == INADDR_ANY )
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goto fallback;
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/*
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* Is it for a local address on this host?
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*/
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LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
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if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
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goto fallback;
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}
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/*
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* Or is it for a local IP broadcast address on this host?
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*/
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if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
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TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
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if (ifa->ifa_addr->sa_family != AF_INET)
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continue;
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ia = ifatoia(ifa);
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if (ia->ia_netbroadcast.s_addr == ip->ip_dst.s_addr)
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goto fallback;
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if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
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ip->ip_dst.s_addr)
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goto fallback;
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continue;
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fallback:
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/* return packet back to netisr for slow processing */
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ip->ip_len = htons(ip->ip_len);
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ip->ip_off = htons(ip->ip_off);
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return 0;
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}
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}
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ipstat.ips_total++;
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/*
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* Step 3: incoming packet firewall processing
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*/
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odest = dest = ip->ip_dst.s_addr;
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#ifdef PFIL_HOOKS
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/*
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* Run through list of ipfilter hooks for input packets
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*/
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if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN) ||
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m == NULL)
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return 1;
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M_ASSERTVALID(m);
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M_ASSERTPKTHDR(m);
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ip = mtod(m, struct ip *); /* m may have changed by pfil hook */
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dest = ip->ip_dst.s_addr;
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#endif
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/*
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* Run through ipfw for input packets
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*/
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if (fw_enable && IPFW_LOADED) {
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bzero(&args, sizeof(args));
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args.m = m;
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ipfw = ip_fw_chk_ptr(&args);
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m = args.m;
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M_ASSERTVALID(m);
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M_ASSERTPKTHDR(m);
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/*
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* Packet denied, drop it
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*/
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if ((ipfw & IP_FW_PORT_DENY_FLAG) || m == NULL)
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goto drop;
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/*
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* Send packet to the appropriate pipe
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*/
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if (DUMMYNET_LOADED && (ipfw & IP_FW_PORT_DYNT_FLAG) != 0) {
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ip_dn_io_ptr(m, ipfw & 0xffff, DN_TO_IP_IN, &args);
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return 1;
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}
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#ifdef IPDIVERT
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/*
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* Divert packet
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*/
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if (ipfw != 0 && (ipfw & IP_FW_PORT_DYNT_FLAG) == 0) {
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/*
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* See if this is a fragment
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*/
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if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
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MGETHDR(tag, M_DONTWAIT, MT_TAG);
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if (tag == NULL)
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goto drop;
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tag->m_flags = PACKET_TAG_DIVERT;
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tag->m_data = (caddr_t)(intptr_t)args.divert_rule;
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tag->m_next = m;
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/* XXX: really bloody hack, see ip_input */
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tag->m_nextpkt = (struct mbuf *)1;
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m = tag;
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tag = NULL;
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goto droptoours;
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}
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/*
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* Tee packet
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*/
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if ((ipfw & IP_FW_PORT_TEE_FLAG) != 0)
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teem = m_dup(m, M_DONTWAIT);
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else
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teem = m;
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if (teem == NULL)
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goto passin;
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/*
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* Delayed checksums are not compatible
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*/
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if (teem->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
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in_delayed_cksum(teem);
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teem->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
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}
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/*
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* Restore packet header fields to original values
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*/
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tip = mtod(teem, struct ip *);
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tip->ip_len = htons(tip->ip_len);
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tip->ip_off = htons(tip->ip_off);
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/*
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* Deliver packet to divert input routine
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*/
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divert_packet(teem, 0, ipfw & 0xffff, args.divert_rule);
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/*
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* If this was not tee, we are done
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*/
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if ((ipfw & IP_FW_PORT_TEE_FLAG) == 0)
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return 1;
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/* Continue if it was tee */
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goto passin;
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}
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#endif
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if (ipfw == 0 && args.next_hop != NULL) {
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dest = args.next_hop->sin_addr.s_addr;
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goto passin;
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}
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/*
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* Let through or not?
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*/
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if (ipfw != 0)
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goto drop;
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}
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passin:
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ip = mtod(m, struct ip *); /* if m changed during fw processing */
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/*
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* Destination address changed?
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*/
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if (odest != dest) {
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/*
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* Is it now for a local address on this host?
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*/
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LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
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if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
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goto forwardlocal;
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}
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/*
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* Go on with new destination address
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*/
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}
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/*
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* Step 4: decrement TTL and look up route
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*/
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/*
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* Check TTL
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*/
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#ifdef IPSTEALTH
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if (!ipstealth) {
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#endif
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if (ip->ip_ttl <= IPTTLDEC) {
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icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, NULL, NULL);
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return 1;
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}
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/*
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* Decrement the TTL and incrementally change the checksum.
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* Don't bother doing this with hw checksum offloading.
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*/
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ip->ip_ttl -= IPTTLDEC;
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if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
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ip->ip_sum -= ~htons(IPTTLDEC << 8);
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else
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ip->ip_sum += htons(IPTTLDEC << 8);
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#ifdef IPSTEALTH
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}
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#endif
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/*
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* Find route to destination.
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*/
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bzero(&ro, sizeof(ro));
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dst = (struct sockaddr_in *)&ro.ro_dst;
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dst->sin_family = AF_INET;
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dst->sin_len = sizeof(*dst);
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dst->sin_addr.s_addr = dest;
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rtalloc_ign(&ro, (RTF_PRCLONING | RTF_CLONING));
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/*
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* Route there and interface still up?
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*/
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if (ro.ro_rt &&
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(ro.ro_rt->rt_flags & RTF_UP) &&
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(ro.ro_rt->rt_ifp->if_flags & IFF_UP)) {
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ia = ifatoia(ro.ro_rt->rt_ifa);
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ifp = ro.ro_rt->rt_ifp;
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if (ro.ro_rt->rt_flags & RTF_GATEWAY)
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dst = (struct sockaddr_in *)ro.ro_rt->rt_gateway;
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} else {
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ipstat.ips_noroute++;
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ipstat.ips_cantforward++;
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icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, NULL, NULL);
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if (ro.ro_rt)
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RTFREE(ro.ro_rt);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Step 5: outgoing firewall packet processing
|
|
*/
|
|
|
|
#ifdef PFIL_HOOKS
|
|
/*
|
|
* Run through list of hooks for output packets.
|
|
*/
|
|
if (pfil_run_hooks(&inet_pfil_hook, &m, ifp, PFIL_OUT) || m == NULL) {
|
|
RTFREE(ro.ro_rt);
|
|
return 1;
|
|
}
|
|
|
|
M_ASSERTVALID(m);
|
|
M_ASSERTPKTHDR(m);
|
|
|
|
ip = mtod(m, struct ip *);
|
|
dest = ip->ip_dst.s_addr;
|
|
#endif
|
|
if (fw_enable && IPFW_LOADED && !args.next_hop) {
|
|
bzero(&args, sizeof(args));
|
|
args.m = m;
|
|
args.oif = ifp;
|
|
|
|
ipfw = ip_fw_chk_ptr(&args);
|
|
m = args.m;
|
|
|
|
M_ASSERTVALID(m);
|
|
M_ASSERTPKTHDR(m);
|
|
|
|
if ((ipfw & IP_FW_PORT_DENY_FLAG) || m == NULL) {
|
|
RTFREE(ro.ro_rt);
|
|
goto drop;
|
|
}
|
|
if (DUMMYNET_LOADED && (ipfw & IP_FW_PORT_DYNT_FLAG) != 0) {
|
|
/*
|
|
* XXX note: if the ifp or rt entry are deleted
|
|
* while a pkt is in dummynet, we are in trouble!
|
|
*/
|
|
args.ro = &ro; /* dummynet does not save it */
|
|
args.dst = dst;
|
|
|
|
ip_dn_io_ptr(m, ipfw & 0xffff, DN_TO_IP_OUT, &args);
|
|
RTFREE(ro.ro_rt);
|
|
return 1;
|
|
}
|
|
#ifdef IPDIVERT
|
|
if (ipfw != 0 && (ipfw & IP_FW_PORT_DYNT_FLAG) == 0) {
|
|
/*
|
|
* See if this is a fragment
|
|
*/
|
|
if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
|
|
MGETHDR(tag, M_DONTWAIT, MT_TAG);
|
|
if (tag == NULL) {
|
|
RTFREE(ro.ro_rt);
|
|
goto drop;
|
|
}
|
|
tag->m_flags = PACKET_TAG_DIVERT;
|
|
tag->m_data = (caddr_t)(intptr_t)args.divert_rule;
|
|
tag->m_next = m;
|
|
/* XXX: really bloody hack, see ip_input */
|
|
tag->m_nextpkt = (struct mbuf *)1;
|
|
m = tag;
|
|
tag = NULL;
|
|
|
|
goto droptoours;
|
|
}
|
|
/*
|
|
* Tee packet
|
|
*/
|
|
if ((ipfw & IP_FW_PORT_TEE_FLAG) != 0)
|
|
teem = m_dup(m, M_DONTWAIT);
|
|
else
|
|
teem = m;
|
|
if (teem == NULL)
|
|
goto passout;
|
|
|
|
/*
|
|
* Delayed checksums are not compatible with divert
|
|
*/
|
|
if (teem->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
|
|
in_delayed_cksum(teem);
|
|
teem->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
|
|
}
|
|
/*
|
|
* Restore packet header fields to original values
|
|
*/
|
|
tip = mtod(teem, struct ip *);
|
|
tip->ip_len = htons(tip->ip_len);
|
|
tip->ip_off = htons(tip->ip_off);
|
|
/*
|
|
* Deliver packet to divert input routine
|
|
*/
|
|
divert_packet(teem, 0, ipfw & 0xffff, args.divert_rule);
|
|
/*
|
|
* If this was not tee, we are done
|
|
*/
|
|
if ((ipfw & IP_FW_PORT_TEE_FLAG) == 0) {
|
|
RTFREE(ro.ro_rt);
|
|
return 1;
|
|
}
|
|
/* Continue if it was tee */
|
|
goto passout;
|
|
}
|
|
#endif
|
|
if (ipfw == 0 && args.next_hop != NULL) {
|
|
dest = args.next_hop->sin_addr.s_addr;
|
|
goto passout;
|
|
}
|
|
/*
|
|
* Let through or not?
|
|
*/
|
|
if (ipfw != 0)
|
|
goto drop;
|
|
}
|
|
passout:
|
|
ip = mtod(m, struct ip *);
|
|
|
|
/*
|
|
* Destination address changed?
|
|
*/
|
|
if (odest != dest) {
|
|
/*
|
|
* Is it now for a local address on this host?
|
|
*/
|
|
LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
|
|
if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) {
|
|
forwardlocal:
|
|
if (args.next_hop) {
|
|
/* XXX leak */
|
|
MGETHDR(tag, M_DONTWAIT, MT_TAG);
|
|
if (tag == NULL) {
|
|
if (ro.ro_rt)
|
|
RTFREE(ro.ro_rt);
|
|
goto drop;
|
|
}
|
|
tag->m_flags = PACKET_TAG_IPFORWARD;
|
|
tag->m_data = (caddr_t)args.next_hop;
|
|
tag->m_next = m;
|
|
/* XXX: really bloody hack,
|
|
* see ip_input */
|
|
tag->m_nextpkt = (struct mbuf *)1;
|
|
m = tag;
|
|
tag = NULL;
|
|
}
|
|
#ifdef IPDIVERT
|
|
droptoours: /* Used for DIVERT */
|
|
#endif
|
|
MGETHDR(tag, M_DONTWAIT, MT_TAG);
|
|
if (tag == NULL) {
|
|
if (ro.ro_rt)
|
|
RTFREE(ro.ro_rt);
|
|
goto drop;
|
|
}
|
|
tag->m_flags = PACKET_TAG_IPFASTFWD_OURS;
|
|
tag->m_data = NULL;
|
|
tag->m_next = m;
|
|
/* XXX: really bloody hack, see ip_input */
|
|
tag->m_nextpkt = (struct mbuf *)1;
|
|
m = tag;
|
|
tag = NULL;
|
|
|
|
/* ip still points to the real packet */
|
|
ip->ip_len = htons(ip->ip_len);
|
|
ip->ip_off = htons(ip->ip_off);
|
|
|
|
/*
|
|
* Return packet for processing by ip_input
|
|
*/
|
|
if (ro.ro_rt)
|
|
RTFREE(ro.ro_rt);
|
|
return 0;
|
|
}
|
|
}
|
|
/*
|
|
* Redo route lookup with new destination address
|
|
*/
|
|
RTFREE(ro.ro_rt);
|
|
bzero(&ro, sizeof(ro));
|
|
dst = (struct sockaddr_in *)&ro.ro_dst;
|
|
dst->sin_family = AF_INET;
|
|
dst->sin_len = sizeof(*dst);
|
|
dst->sin_addr.s_addr = dest;
|
|
rtalloc_ign(&ro, (RTF_PRCLONING | RTF_CLONING));
|
|
|
|
/*
|
|
* Route there and interface still up?
|
|
*/
|
|
if (ro.ro_rt &&
|
|
(ro.ro_rt->rt_flags & RTF_UP) &&
|
|
(ro.ro_rt->rt_ifp->if_flags & IFF_UP)) {
|
|
ia = ifatoia(ro.ro_rt->rt_ifa);
|
|
ifp = ro.ro_rt->rt_ifp;
|
|
if (ro.ro_rt->rt_flags & RTF_GATEWAY)
|
|
dst = (struct sockaddr_in *)ro.ro_rt->rt_gateway;
|
|
} else {
|
|
ipstat.ips_noroute++;
|
|
ipstat.ips_cantforward++;
|
|
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST,
|
|
NULL, NULL);
|
|
if (ro.ro_rt)
|
|
RTFREE(ro.ro_rt);
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Step 6: send off the packet
|
|
*/
|
|
|
|
/*
|
|
* Check if packet fits MTU or if hardware will fragement for us
|
|
*/
|
|
if (ro.ro_rt->rt_rmx.rmx_mtu)
|
|
mtu = min(ro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu);
|
|
else
|
|
mtu = ifp->if_mtu;
|
|
|
|
if (ip->ip_len <= mtu ||
|
|
(ifp->if_hwassist & CSUM_FRAGMENT && (ip->ip_off & IP_DF) == 0)) {
|
|
/*
|
|
* Restore packet header fields to original values
|
|
*/
|
|
ip->ip_len = htons(ip->ip_len);
|
|
ip->ip_off = htons(ip->ip_off);
|
|
/*
|
|
* Send off the packet via outgoing interface
|
|
*/
|
|
error = (*ifp->if_output)(ifp, m,
|
|
(struct sockaddr *)dst, ro.ro_rt);
|
|
if (ia) {
|
|
ia->ia_ifa.if_opackets++;
|
|
ia->ia_ifa.if_obytes += m->m_pkthdr.len;
|
|
}
|
|
} else {
|
|
/*
|
|
* Handle EMSGSIZE with icmp reply
|
|
* needfrag for TCP MTU discovery
|
|
*/
|
|
if (ip->ip_off & IP_DF) {
|
|
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG,
|
|
NULL, ifp);
|
|
ipstat.ips_cantfrag++;
|
|
RTFREE(ro.ro_rt);
|
|
return 1;
|
|
} else {
|
|
/*
|
|
* We have to fragement the packet
|
|
*/
|
|
m->m_pkthdr.csum_flags |= CSUM_IP;
|
|
if (ip_fragment(ip, &m, mtu, ifp->if_hwassist,
|
|
(~ifp->if_hwassist & CSUM_DELAY_IP))) {
|
|
RTFREE(ro.ro_rt);
|
|
goto drop;
|
|
}
|
|
KASSERT(m != NULL, ("null mbuf and no error"));
|
|
/*
|
|
* Send off the fragments via outgoing interface
|
|
*/
|
|
error = 0;
|
|
do {
|
|
m0 = m->m_nextpkt;
|
|
m->m_nextpkt = NULL;
|
|
|
|
error = (*ifp->if_output)(ifp, m,
|
|
(struct sockaddr *)dst, ro.ro_rt);
|
|
if (error)
|
|
break;
|
|
} while ((m = m0) != NULL);
|
|
if (error) {
|
|
/* Reclaim remaining fragments */
|
|
for (; m; m = m0) {
|
|
m0 = m->m_nextpkt;
|
|
m->m_nextpkt = NULL;
|
|
m_freem(m);
|
|
}
|
|
} else
|
|
ipstat.ips_fragmented++;
|
|
}
|
|
}
|
|
|
|
if (error != 0)
|
|
ipstat.ips_odropped++;
|
|
else {
|
|
ro.ro_rt->rt_rmx.rmx_pksent++;
|
|
ipstat.ips_forward++;
|
|
ipstat.ips_fastforward++;
|
|
}
|
|
RTFREE(ro.ro_rt);
|
|
return 1;
|
|
drop:
|
|
if (m)
|
|
m_freem(m);
|
|
return 1;
|
|
}
|