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From: "Alexander V. Chernikov" <melifaro@FreeBSD.org>
Date: Tue, 26 Mar 2013 18:57:25 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r248743 - stable/9/sys/net
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Author: melifaro
Date: Tue Mar 26 18:57:25 2013
New Revision: 248743
URL: http://svnweb.freebsd.org/changeset/base/248743

Log:
  Permit changing MTU in 6to4 relay.
  
  This behavior is recommended by RFC 4213 clause 3.2.
  
  Sometimes fragmentation is the least evil.
  For example, some Linux IPVS kernels forwards
  ICMPv6 checksums to real servers incorrectly.

Modified:
  stable/9/sys/net/if_stf.c
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/net/   (props changed)

Modified: stable/9/sys/net/if_stf.c
==============================================================================
--- stable/9/sys/net/if_stf.c	Tue Mar 26 18:46:40 2013	(r248742)
+++ stable/9/sys/net/if_stf.c	Tue Mar 26 18:57:25 2013	(r248743)
@@ -799,7 +799,7 @@ stf_rtrequest(cmd, rt, info)
 	struct rt_addrinfo *info;
 {
 	RT_LOCK_ASSERT(rt);
-	rt->rt_rmx.rmx_mtu = IPV6_MMTU;
+	rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
 }
 
 static int
@@ -812,7 +812,7 @@ stf_ioctl(ifp, cmd, data)
 	struct ifreq *ifr;
 	struct sockaddr_in6 *sin6;
 	struct in_addr addr;
-	int error;
+	int error, mtu;
 
 	error = 0;
 	switch (cmd) {
@@ -846,6 +846,18 @@ stf_ioctl(ifp, cmd, data)
 			error = EAFNOSUPPORT;
 		break;
 
+	case SIOCGIFMTU:
+		break;
+
+	case SIOCSIFMTU:
+		ifr = (struct ifreq *)data;
+		mtu = ifr->ifr_mtu;
+		/* RFC 4213 3.2 ideal world MTU */
+		if (mtu < IPV6_MINMTU || mtu > IF_MAXMTU - 20)
+			return (EINVAL);
+		ifp->if_mtu = mtu;
+		break;
+
 	default:
 		error = EINVAL;
 		break;