strictly follow RFC2460 section 5 last paragraph
(sending rule when PMTU < 1280). pointed out by guninski at guninski.com
This commit is contained in:
itojun
parent
4648495436
commit
70e51fdcf0
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@ -1,4 +1,4 @@
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/* $NetBSD: ip6_output.c,v 1.77 2004/01/24 13:02:41 darrenr Exp $ */
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/* $NetBSD: ip6_output.c,v 1.78 2004/02/04 05:17:28 itojun Exp $ */
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/* $KAME: ip6_output.c,v 1.172 2001/03/25 09:55:56 itojun Exp $ */
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/*
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@ -62,7 +62,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: ip6_output.c,v 1.77 2004/01/24 13:02:41 darrenr Exp $");
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__KERNEL_RCSID(0, "$NetBSD: ip6_output.c,v 1.78 2004/02/04 05:17:28 itojun Exp $");
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#include "opt_inet.h"
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#include "opt_ipsec.h"
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@ -91,6 +91,7 @@ __KERNEL_RCSID(0, "$NetBSD: ip6_output.c,v 1.77 2004/01/24 13:02:41 darrenr Exp
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#include <netinet6/ip6_var.h>
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#include <netinet6/in6_pcb.h>
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#include <netinet6/nd6.h>
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#include <netinet6/ip6protosw.h>
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#ifdef IPSEC
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#include <netinet6/ipsec.h>
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@ -122,6 +123,8 @@ static int ip6_insertfraghdr __P((struct mbuf *, struct mbuf *, int,
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struct ip6_frag **));
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static int ip6_insert_jumboopt __P((struct ip6_exthdrs *, u_int32_t));
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static int ip6_splithdr __P((struct mbuf *, struct ip6_exthdrs *));
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static int ip6_getpmtu __P((struct route_in6 *, struct route_in6 *,
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struct ifnet *, struct in6_addr *, u_long *, int *));
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extern struct ifnet loif[NLOOP];
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@ -154,6 +157,7 @@ ip6_output(m0, opt, ro, flags, im6o, so, ifpp)
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struct sockaddr_in6 *dst;
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int error = 0;
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u_long mtu;
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int alwaysfrag, dontfrag;
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u_int32_t optlen = 0, plen = 0, unfragpartlen = 0;
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struct ip6_exthdrs exthdrs;
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struct in6_addr finaldst;
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@ -308,7 +312,8 @@ ip6_output(m0, opt, ro, flags, im6o, so, ifpp)
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/*
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* we treat dest2 specially. this makes IPsec processing
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* much easier.
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* much easier. the goal here is to make mprev point the
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* mbuf prior to dest2.
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*
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* result: IPv6 dest2 payload
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* m and mprev will point to IPv6 header.
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@ -371,7 +376,7 @@ ip6_output(m0, opt, ro, flags, im6o, so, ifpp)
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bzero(&state, sizeof(state));
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state.m = m;
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error = ipsec6_output_trans(&state, nexthdrp, mprev, sp, flags,
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&needipsectun);
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&needipsectun);
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m = state.m;
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if (error) {
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/* mbuf is already reclaimed in ipsec6_output_trans. */
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@ -447,6 +452,7 @@ skip_ipsec2:;
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/*
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* Route packet.
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*/
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/* initialize cached route */
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if (ro == 0) {
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ro = &ip6route;
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bzero((caddr_t)ro, sizeof(*ro));
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@ -708,7 +714,8 @@ skip_ipsec2:;
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*ifpp = ifp;
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/* Determine path MTU. */
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if ((error = ip6_getpmtu(ro_pmtu, ro, ifp, &finaldst, &mtu)) != 0)
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if ((error = ip6_getpmtu(ro_pmtu, ro, ifp, &finaldst, &mtu,
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&alwaysfrag)) != 0)
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goto bad;
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/*
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@ -805,34 +812,82 @@ skip_ipsec2:;
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/*
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* Send the packet to the outgoing interface.
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* If necessary, do IPv6 fragmentation before sending.
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*
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* the logic here is rather complex:
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* 1: normal case (dontfrag == 0, alwaysfrag == 0)
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* 1-a: send as is if tlen <= path mtu
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* 1-b: fragment if tlen > path mtu
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*
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* 2: if user asks us not to fragment (dontfrag == 1)
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* 2-a: send as is if tlen <= interface mtu
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* 2-b: error if tlen > interface mtu
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*
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* 3: if we always need to attach fragment header (alwaysfrag == 1)
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* always fragment
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*
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* 4: if dontfrag == 1 && alwaysfrag == 1
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* error, as we cannot handle this conflicting request
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*/
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tlen = m->m_pkthdr.len;
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if (tlen <= mtu) {
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#ifdef IFA_STATS
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dontfrag = 0;
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if (dontfrag && alwaysfrag) { /* case 4 */
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/* conflicting request - can't transmit */
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error = EMSGSIZE;
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goto bad;
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}
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if (dontfrag && tlen > IN6_LINKMTU(ifp)) { /* case 2-b */
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/*
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* Even if the DONTFRAG option is specified, we cannot send the
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* packet when the data length is larger than the MTU of the
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* outgoing interface.
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* Notify the error by sending IPV6_PATHMTU ancillary data as
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* well as returning an error code (the latter is not described
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* in the API spec.)
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*/
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u_int32_t mtu32;
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struct ip6ctlparam ip6cp;
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mtu32 = (u_int32_t)mtu;
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bzero(&ip6cp, sizeof(ip6cp));
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ip6cp.ip6c_cmdarg = (void *)&mtu32;
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pfctlinput2(PRC_MSGSIZE, (struct sockaddr *)&ro_pmtu->ro_dst,
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(void *)&ip6cp);
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error = EMSGSIZE;
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goto bad;
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}
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/*
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* transmit packet without fragmentation
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*/
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if (dontfrag || (!alwaysfrag && tlen <= mtu)) { /* case 1-a and 2-a */
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struct in6_ifaddr *ia6;
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ip6 = mtod(m, struct ip6_hdr *);
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ia6 = in6_ifawithifp(ifp, &ip6->ip6_src);
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if (ia6) {
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/* Record statistics for this interface address. */
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ia6->ia_ifa.ifa_data.ifad_outbytes +=
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m->m_pkthdr.len;
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ia6->ia_ifa.ifa_data.ifad_outbytes += m->m_pkthdr.len;
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}
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#endif
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#ifdef IPSEC
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/* clean ipsec history once it goes out of the node */
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ipsec_delaux(m);
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#endif
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error = nd6_output(ifp, origifp, m, dst, ro->ro_rt);
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goto done;
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} else if (mtu < IPV6_MMTU) {
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/*
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* note that path MTU is never less than IPV6_MMTU
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* (see icmp6_input).
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*/
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}
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/*
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* try to fragment the packet. case 1-b and 3
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*/
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if (mtu < IPV6_MMTU) {
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/* path MTU cannot be less than IPV6_MMTU */
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error = EMSGSIZE;
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in6_ifstat_inc(ifp, ifs6_out_fragfail);
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goto bad;
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} else if (ip6->ip6_plen == 0) { /* jumbo payload cannot be fragmented */
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} else if (ip6->ip6_plen == 0) {
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/* jumbo payload cannot be fragmented */
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error = EMSGSIZE;
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in6_ifstat_inc(ifp, ifs6_out_fragfail);
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goto bad;
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struct ip6_frag *ip6f;
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u_int32_t id = htonl(ip6_randomid());
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u_char nextproto;
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struct ip6ctlparam ip6cp;
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u_int32_t mtu32;
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/*
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* Too large for the destination or interface;
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hlen = unfragpartlen;
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if (mtu > IPV6_MAXPACKET)
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mtu = IPV6_MAXPACKET;
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/* Notify a proper path MTU to applications. */
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mtu32 = (u_int32_t)mtu;
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bzero(&ip6cp, sizeof(ip6cp));
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ip6cp.ip6c_cmdarg = (void *)&mtu32;
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pfctlinput2(PRC_MSGSIZE, (struct sockaddr *)&ro_pmtu->ro_dst,
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(void *)&ip6cp);
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len = (mtu - hlen - sizeof(struct ip6_frag)) & ~7;
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if (len < 8) {
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error = EMSGSIZE;
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ip6stat.ip6s_odropped++;
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goto sendorfree;
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}
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m->m_pkthdr.rcvif = NULL;
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m->m_flags = m0->m_flags & M_COPYFLAGS;
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*mnext = m;
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mnext = &m->m_nextpkt;
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m0 = m->m_nextpkt;
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m->m_nextpkt = 0;
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if (error == 0) {
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#ifdef IFA_STATS
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struct in6_ifaddr *ia6;
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ip6 = mtod(m, struct ip6_hdr *);
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ia6 = in6_ifawithifp(ifp, &ip6->ip6_src);
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* address.
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*/
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ia6->ia_ifa.ifa_data.ifad_outbytes +=
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m->m_pkthdr.len;
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m->m_pkthdr.len;
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}
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#endif
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#ifdef IPSEC
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/* clean ipsec history once it goes out of the node */
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ipsec_delaux(m);
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@ -1087,7 +1151,7 @@ ip6_insert_jumboopt(exthdrs, plen)
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return (ENOBUFS);
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n->m_len = oldoptlen + JUMBOOPTLEN;
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bcopy(mtod(mopt, caddr_t), mtod(n, caddr_t),
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oldoptlen);
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oldoptlen);
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optbuf = mtod(n, u_int8_t *) + oldoptlen;
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m_freem(mopt);
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mopt = exthdrs->ip6e_hbh = n;
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return (0);
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}
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int
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ip6_getpmtu(ro_pmtu, ro, ifp, dst, mtup)
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static int
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ip6_getpmtu(ro_pmtu, ro, ifp, dst, mtup, alwaysfragp)
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#ifdef NEW_STRUCT_ROUTE
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struct route *ro_pmtu, *ro;
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#else
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struct route_in6 *ro_pmtu, *ro;
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#endif
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struct ifnet *ifp;
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struct in6_addr *dst;
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u_long *mtup;
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int *alwaysfragp;
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{
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u_int32_t mtu = 0;
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int alwaysfrag = 0;
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int error = 0;
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if (ro_pmtu != ro) {
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@ -1181,17 +1251,21 @@ ip6_getpmtu(ro_pmtu, ro, ifp, dst, mtup)
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(struct sockaddr_in6 *)&ro_pmtu->ro_dst;
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if (ro_pmtu->ro_rt &&
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((ro_pmtu->ro_rt->rt_flags & RTF_UP) == 0 ||
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!IN6_ARE_ADDR_EQUAL(&sa6_dst->sin6_addr, dst))) {
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!IN6_ARE_ADDR_EQUAL(&sa6_dst->sin6_addr, dst))) {
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RTFREE(ro_pmtu->ro_rt);
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ro_pmtu->ro_rt = (struct rtentry *)0;
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ro_pmtu->ro_rt = (struct rtentry *)NULL;
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}
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if (ro_pmtu->ro_rt == 0) {
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bzero(sa6_dst, sizeof(*sa6_dst));
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if (ro_pmtu->ro_rt == NULL) {
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bzero(sa6_dst, sizeof(*sa6_dst)); /* for safety */
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sa6_dst->sin6_family = AF_INET6;
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sa6_dst->sin6_len = sizeof(struct sockaddr_in6);
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sa6_dst->sin6_addr = *dst;
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#ifdef __bsdi__ /* bsdi needs rtcalloc to clone a route. */
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rtcalloc((struct route *)ro_pmtu);
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#else
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rtalloc((struct route *)ro_pmtu);
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#endif
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}
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}
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if (ro_pmtu->ro_rt) {
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@ -1203,7 +1277,18 @@ ip6_getpmtu(ro_pmtu, ro, ifp, dst, mtup)
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mtu = ro_pmtu->ro_rt->rt_rmx.rmx_mtu;
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if (mtu == 0)
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mtu = ifmtu;
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else if (mtu > ifmtu) {
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else if (mtu < IPV6_MMTU) {
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/*
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* RFC2460 section 5, last paragraph:
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* if we record ICMPv6 too big message with
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* mtu < IPV6_MMTU, transmit packets sized IPV6_MMTU
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* or smaller, with fragment header attached.
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* (fragment header is needed regardless from the
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* packet size, for translators to identify packets)
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*/
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alwaysfrag = 1;
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mtu = IPV6_MMTU;
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} else if (mtu > ifmtu) {
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/*
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* The MTU on the route is larger than the MTU on
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* the interface! This shouldn't happen, unless the
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@ -1211,9 +1296,6 @@ ip6_getpmtu(ro_pmtu, ro, ifp, dst, mtup)
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* interface was brought up. Change the MTU in the
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* route to match the interface MTU (as long as the
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* field isn't locked).
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*
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* if MTU on the route is 0, we need to fix the MTU.
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* this case happens with path MTU discovery timeouts.
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*/
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mtu = ifmtu;
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if (!(ro_pmtu->ro_rt->rt_rmx.rmx_locks & RTV_MTU))
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@ -1225,6 +1307,8 @@ ip6_getpmtu(ro_pmtu, ro, ifp, dst, mtup)
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error = EHOSTUNREACH; /* XXX */
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*mtup = mtu;
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if (alwaysfragp)
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*alwaysfragp = alwaysfrag;
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return (error);
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}
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