make use of the host route's mtu for processing. This means we can now
support a network w/ split mtu's by assigning each host route the correct mtu. an aspiring programmer could write a daemon to probe hosts and find out if they support a larger mtu.
This commit is contained in:
parent
805def2e04
commit
3ae2ad088e
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=162205
@ -112,6 +112,7 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
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struct ifnet *ifp = NULL; /* keep compiler happy */
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struct mbuf *m0;
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int hlen = sizeof (struct ip);
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int mtu;
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int len, error = 0;
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struct sockaddr_in *dst = NULL; /* keep compiler happy */
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struct in_ifaddr *ia = NULL;
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@ -172,7 +173,7 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
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dst->sin_family != AF_INET ||
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dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
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RTFREE(ro->ro_rt);
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ro->ro_rt = (struct rtentry *)0;
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ro->ro_rt = (struct rtentry *)NULL;
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}
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#ifdef IPFIREWALL_FORWARD
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if (ro->ro_rt == NULL && fwd_tag == NULL) {
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@ -241,6 +242,24 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
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else
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isbroadcast = in_broadcast(dst->sin_addr, ifp);
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}
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/*
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* Calculate MTU. If we have a route that is up, use that,
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* otherwise use the interface's MTU.
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*/
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if (ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST)) {
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/*
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* This case can happen if the user changed the MTU
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* of an interface after enabling IP on it. Because
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* most netifs don't keep track of routes pointing to
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* them, there is no way for one to update all its
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* routes when the MTU is changed.
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*/
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if (ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)
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ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
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mtu = ro->ro_rt->rt_rmx.rmx_mtu;
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} else {
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mtu = ifp->if_mtu;
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}
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if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
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struct in_multi *inm;
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@ -360,10 +379,10 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
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*/
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#ifdef ALTQ
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if ((!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
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((ifp->if_snd.ifq_len + ip->ip_len / ifp->if_mtu + 1) >=
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((ifp->if_snd.ifq_len + ip->ip_len / mtu + 1) >=
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ifp->if_snd.ifq_maxlen))
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#else
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if ((ifp->if_snd.ifq_len + ip->ip_len / ifp->if_mtu + 1) >=
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if ((ifp->if_snd.ifq_len + ip->ip_len / mtu + 1) >=
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ifp->if_snd.ifq_maxlen)
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#endif /* ALTQ */
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{
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@ -388,7 +407,7 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
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goto bad;
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}
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/* don't allow broadcast messages to be fragmented */
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if (ip->ip_len > ifp->if_mtu) {
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if (ip->ip_len > mtu) {
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error = EMSGSIZE;
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goto bad;
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}
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@ -497,7 +516,7 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
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* If small enough for interface, or the interface will take
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* care of the fragmentation for us, we can just send directly.
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*/
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if (ip->ip_len <= ifp->if_mtu ||
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if (ip->ip_len <= mtu ||
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(m->m_pkthdr.csum_flags & ifp->if_hwassist & CSUM_TSO) != 0 ||
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((ip->ip_off & IP_DF) == 0 && (ifp->if_hwassist & CSUM_FRAGMENT))) {
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ip->ip_len = htons(ip->ip_len);
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@ -542,18 +561,6 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
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/* Balk when DF bit is set or the interface didn't support TSO. */
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if ((ip->ip_off & IP_DF) || (m->m_pkthdr.csum_flags & CSUM_TSO)) {
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error = EMSGSIZE;
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/*
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* This case can happen if the user changed the MTU
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* of an interface after enabling IP on it. Because
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* most netifs don't keep track of routes pointing to
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* them, there is no way for one to update all its
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* routes when the MTU is changed.
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*/
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if (ro != NULL &&
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(ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST)) &&
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(ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)) {
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ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
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}
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ipstat.ips_cantfrag++;
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goto bad;
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}
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@ -562,7 +569,7 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
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* Too large for interface; fragment if possible. If successful,
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* on return, m will point to a list of packets to be sent.
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*/
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error = ip_fragment(ip, &m, ifp->if_mtu, ifp->if_hwassist, sw_csum);
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error = ip_fragment(ip, &m, mtu, ifp->if_hwassist, sw_csum);
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if (error)
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goto bad;
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for (; m; m = m0) {
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