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Fix path MTU discovery for TCP LRO/TSO when forwarding.
When doing LRO (Large Receive Offload), the drivers, currently ix(4) and lo(4) only, record an upper bound of the size of the original packets in ph_mss. When sending, either stack or hardware must chop the packets with TSO (TCP Segmentation Offload) to that size. That means we have to call tcp_if_output_tso() before ifp->if_output(). Put that logic into if_output_tso() to avoid code duplication. As TCP packets on the wire do not get larger that way, path MTU discovery should still work. tested by and OK jan@
This commit is contained in:
bluhm
parent
0b88608e55
commit
5ebaba9d29
53
sys/net/if.c
53
sys/net/if.c
@ -1,4 +1,4 @@
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/* $OpenBSD: if.c,v 1.704 2023/07/06 04:55:04 dlg Exp $ */
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/* $OpenBSD: if.c,v 1.705 2023/07/07 08:05:02 bluhm Exp $ */
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/* $NetBSD: if.c,v 1.35 1996/05/07 05:26:04 thorpej Exp $ */
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/*
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@ -885,6 +885,57 @@ if_output_ml(struct ifnet *ifp, struct mbuf_list *ml,
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return error;
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}
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int
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if_output_tso(struct ifnet *ifp, struct mbuf **mp, struct sockaddr *dst,
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struct rtentry *rt, u_int mtu)
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{
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uint32_t ifcap;
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int error;
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switch (dst->sa_family) {
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case AF_INET:
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ifcap = IFCAP_TSOv4;
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break;
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#ifdef INET6
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case AF_INET6:
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ifcap = IFCAP_TSOv6;
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break;
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#endif
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default:
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unhandled_af(dst->sa_family);
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}
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/*
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* Try to send with TSO first. When forwarding LRO may set
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* maximium segment size in mbuf header. Chop TCP segment
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* even if it would fit interface MTU to preserve maximum
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* path MTU.
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*/
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error = tcp_if_output_tso(ifp, mp, dst, rt, ifcap, mtu);
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if (error || *mp == NULL)
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return error;
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if ((*mp)->m_pkthdr.len <= mtu) {
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switch (dst->sa_family) {
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case AF_INET:
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in_hdr_cksum_out(*mp, ifp);
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in_proto_cksum_out(*mp, ifp);
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break;
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#ifdef INET6
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case AF_INET6:
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in6_proto_cksum_out(*mp, ifp);
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break;
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#endif
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}
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error = ifp->if_output(ifp, *mp, dst, rt);
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*mp = NULL;
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return error;
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}
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/* mp still contains mbuf that has to be fragmented or dropped. */
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return 0;
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}
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int
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if_output_mq(struct ifnet *ifp, struct mbuf_queue *mq, unsigned int *total,
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struct sockaddr *dst, struct rtentry *rt)
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@ -1,4 +1,4 @@
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/* $OpenBSD: if_var.h,v 1.128 2023/06/28 11:49:49 kn Exp $ */
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/* $OpenBSD: if_var.h,v 1.129 2023/07/07 08:05:02 bluhm Exp $ */
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/* $NetBSD: if.h,v 1.23 1996/05/07 02:40:27 thorpej Exp $ */
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/*
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@ -329,6 +329,8 @@ int if_output_ml(struct ifnet *, struct mbuf_list *,
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struct sockaddr *, struct rtentry *);
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int if_output_mq(struct ifnet *, struct mbuf_queue *, unsigned int *,
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struct sockaddr *, struct rtentry *);
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int if_output_tso(struct ifnet *, struct mbuf **, struct sockaddr *,
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struct rtentry *, u_int);
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int if_output_local(struct ifnet *, struct mbuf *, sa_family_t);
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void if_rtrequest_dummy(struct ifnet *, int, struct rtentry *);
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void p2p_rtrequest(struct ifnet *, int, struct rtentry *);
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23
sys/net/pf.c
23
sys/net/pf.c
@ -1,4 +1,4 @@
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/* $OpenBSD: pf.c,v 1.1182 2023/07/06 04:55:05 dlg Exp $ */
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/* $OpenBSD: pf.c,v 1.1183 2023/07/07 08:05:02 bluhm Exp $ */
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/*
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* Copyright (c) 2001 Daniel Hartmeier
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@ -6610,15 +6610,8 @@ pf_route(struct pf_pdesc *pd, struct pf_state *st)
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ip = mtod(m0, struct ip *);
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}
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if (ntohs(ip->ip_len) <= ifp->if_mtu) {
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in_hdr_cksum_out(m0, ifp);
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in_proto_cksum_out(m0, ifp);
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ifp->if_output(ifp, m0, sintosa(dst), rt);
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goto done;
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}
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if (tcp_if_output_tso(ifp, &m0, sintosa(dst), rt,
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IFCAP_TSOv4, ifp->if_mtu) || m0 == NULL)
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if (if_output_tso(ifp, &m0, sintosa(dst), rt, ifp->if_mtu) ||
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m0 == NULL)
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goto done;
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/*
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@ -6745,14 +6738,8 @@ pf_route6(struct pf_pdesc *pd, struct pf_state *st)
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goto done;
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}
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if (m0->m_pkthdr.len <= ifp->if_mtu) {
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in6_proto_cksum_out(m0, ifp);
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ifp->if_output(ifp, m0, sin6tosa(dst), rt);
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goto done;
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}
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if (tcp_if_output_tso(ifp, &m0, sin6tosa(dst), rt,
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IFCAP_TSOv6, ifp->if_mtu) || m0 == NULL)
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if (if_output_tso(ifp, &m0, sin6tosa(dst), rt, ifp->if_mtu) ||
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m0 == NULL)
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goto done;
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ip6stat_inc(ip6s_cantfrag);
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@ -1,4 +1,4 @@
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/* $OpenBSD: ip_output.c,v 1.389 2023/07/04 10:48:19 bluhm Exp $ */
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/* $OpenBSD: ip_output.c,v 1.390 2023/07/07 08:05:02 bluhm Exp $ */
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/* $NetBSD: ip_output.c,v 1.28 1996/02/13 23:43:07 christos Exp $ */
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/*
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@ -451,17 +451,9 @@ sendit:
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#endif
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/*
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* If small enough for interface, can just send directly.
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* If TSO or small enough for interface, can just send directly.
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*/
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if (ntohs(ip->ip_len) <= mtu) {
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in_hdr_cksum_out(m, ifp);
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in_proto_cksum_out(m, ifp);
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error = ifp->if_output(ifp, m, sintosa(dst), ro->ro_rt);
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goto done;
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}
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error = tcp_if_output_tso(ifp, &m, sintosa(dst), ro->ro_rt,
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IFCAP_TSOv4, mtu);
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error = if_output_tso(ifp, &m, sintosa(dst), ro->ro_rt, mtu);
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if (error || m == NULL)
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goto done;
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@ -1,4 +1,4 @@
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/* $OpenBSD: ip6_forward.c,v 1.111 2023/06/16 19:18:56 bluhm Exp $ */
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/* $OpenBSD: ip6_forward.c,v 1.112 2023/07/07 08:05:02 bluhm Exp $ */
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/* $KAME: ip6_forward.c,v 1.75 2001/06/29 12:42:13 jinmei Exp $ */
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/*
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@ -319,8 +319,7 @@ reroute:
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}
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#endif
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error = tcp_if_output_tso(ifp, &m, sin6tosa(sin6), rt, IFCAP_TSOv6,
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ifp->if_mtu);
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error = if_output_tso(ifp, &m, sin6tosa(sin6), rt, ifp->if_mtu);
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if (error)
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ip6stat_inc(ip6s_cantforward);
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else if (m == NULL)
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@ -328,17 +327,6 @@ reroute:
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if (error || m == NULL)
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goto senderr;
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/* Check the size after pf_test to give pf a chance to refragment. */
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if (m->m_pkthdr.len <= ifp->if_mtu) {
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in6_proto_cksum_out(m, ifp);
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error = ifp->if_output(ifp, m, sin6tosa(sin6), rt);
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if (error)
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ip6stat_inc(ip6s_cantforward);
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else
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ip6stat_inc(ip6s_forward);
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goto senderr;
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}
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if (mcopy != NULL)
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icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, ifp->if_mtu);
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m_freem(m);
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@ -1,4 +1,4 @@
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/* $OpenBSD: ip6_output.c,v 1.278 2023/06/13 19:34:12 bluhm Exp $ */
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/* $OpenBSD: ip6_output.c,v 1.279 2023/07/07 08:05:02 bluhm 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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@ -677,7 +677,8 @@ reroute:
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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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tlen = m->m_pkthdr.len;
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tlen = ISSET(m->m_pkthdr.csum_flags, M_TCP_TSO) ?
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m->m_pkthdr.ph_mss : m->m_pkthdr.len;
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if (ISSET(m->m_pkthdr.csum_flags, M_IPV6_DF_OUT)) {
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CLR(m->m_pkthdr.csum_flags, M_IPV6_DF_OUT);
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@ -686,9 +687,8 @@ reroute:
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dontfrag = 1;
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else
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dontfrag = 0;
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if (dontfrag && /* case 2-b */
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(ISSET(m->m_pkthdr.csum_flags, M_TCP_TSO) ?
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m->m_pkthdr.ph_mss : tlen) > ifp->if_mtu) {
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if (dontfrag && tlen > ifp->if_mtu) { /* case 2-b */
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#ifdef IPSEC
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if (ip_mtudisc)
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ipsec_adjust_mtu(m, mtu);
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@ -701,16 +701,13 @@ reroute:
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* transmit packet without fragmentation
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*/
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if (dontfrag || tlen <= mtu) { /* case 1-a and 2-a */
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in6_proto_cksum_out(m, ifp);
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error = ifp->if_output(ifp, m, sin6tosa(dst), ro->ro_rt);
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goto done;
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error = if_output_tso(ifp, &m, sin6tosa(dst), ro->ro_rt,
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ifp->if_mtu);
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if (error || m == NULL)
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goto done;
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goto bad; /* should not happen */
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}
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error = tcp_if_output_tso(ifp, &m, sin6tosa(dst), ro->ro_rt,
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IFCAP_TSOv6, mtu);
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if (error || m == NULL)
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goto done;
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/*
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* try to fragment the packet. case 1-b
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*/
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