From 9bf362d0cc3f533a0c7e793fd354bfabfce44de6 Mon Sep 17 00:00:00 2001
From: hrs <hrs@FreeBSD.org>
Date: Sun, 7 Jun 2009 23:00:40 +0000
Subject: Fix and add a workaround on an issue of EtherIP packet with reversed
 version field sent via gif(4)+if_bridge(4).  The EtherIP implementation found
 on FreeBSD 6.1, 6.2, 6.3, 7.0, 7.1, and 7.2 had an interoperability issue
 because it sent the incorrect EtherIP packets and discarded the correct ones.

This change introduces the following two flags to gif(4):

 accept_rev_ethip_ver: accepts both correct EtherIP packets and ones
    with reversed version field, if enabled.  If disabled, the gif
    accepts the correct packets only.  This flag is enabled by
    default.

 send_rev_ethip_ver: sends EtherIP packets with reversed version field
    intentionally, if enabled.  If disabled, the gif sends the correct
    packets only.  This flag is disabled by default.

These flags are stored in struct gif_softc and can be set by
ifconfig(8) on per-interface basis.

Note that this is an incompatible change of EtherIP with the older
FreeBSD releases.  If you need to interoperate older FreeBSD boxes and
new versions after this commit, setting "send_rev_ethip_ver" is
needed.

Reviewed by:	thompsa and rwatson
Spotted by:	Shunsuke SHINOMIYA
PR:		kern/125003
MFC after:	2 weeks
---
 share/man/man4/gif.4       | 31 ++++++++++++++++++++++++++++++-
 share/man/man4/if_bridge.4 |  8 +++++++-
 2 files changed, 37 insertions(+), 2 deletions(-)

(limited to 'share')

diff --git a/share/man/man4/gif.4 b/share/man/man4/gif.4
index 936898f..a70db08 100644
--- a/share/man/man4/gif.4
+++ b/share/man/man4/gif.4
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 10, 1999
+.Dd June 8, 2009
 .Dt GIF 4
 .Os
 .Sh NAME
@@ -256,3 +256,32 @@ had a multi-destination behavior, configurable via
 .Dv IFF_LINK0
 flag.
 The behavior is obsolete and is no longer supported.
+.Pp
+On
+.Fx
+6.1, 6.2, 6.3, 7.0, 7.1, and 7.2
+the
+.Nm
+sends and receives incorrect EtherIP packets with reversed version
+field when
+.Xr if_bridge 4
+is used together.  As a workaround on this interoperability issue, the
+following two
+.Xr ifconfig 8
+flags can be used:
+.Bl -tag -width "accept_rev_ethip_ver" -offset indent
+.It accept_rev_ethip_ver
+accepts both correct EtherIP packets and ones with reversed version
+field, if enabled.  If disabled, the
+.Nm
+accepts the correct packets only.  This flag is enabled by default.
+.It send_rev_ethip_ver
+sends EtherIP packets with reversed version field intentionally, if
+enabled.  If disabled, the
+.Nm
+sends the correct packets only.  This flag is disabled by default.
+.El
+.Pp
+If interoperability with the older
+.Fx
+machines is needed, both of these two flags must be enabled.
diff --git a/share/man/man4/if_bridge.4 b/share/man/man4/if_bridge.4
index 7b31fa1..a31891a 100644
--- a/share/man/man4/if_bridge.4
+++ b/share/man/man4/if_bridge.4
@@ -35,7 +35,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 17, 2007
+.Dd June 8, 2009
 .Dt IF_BRIDGE 4
 .Os
 .Sh NAME
@@ -406,6 +406,12 @@ ifconfig gif0 tunnel 1.2.3.4 5.6.7.8 up
 ifconfig bridge0 create
 ifconfig bridge0 addm fxp0 addm gif0 up
 .Ed
+.Pp
+Note that
+.Fx
+6.1, 6.2, 6.3, 7.0, 7.1, and 7.2 have a bug in the EtherIP protocol.
+For more details and workaround, see
+.Xr gif 4 manual page.
 .Sh SEE ALSO
 .Xr gif 4 ,
 .Xr ipf 4 ,
-- 
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