Add ip route save/restore

This patch adds save and restore commands to "ip route". Save dumps
the RTNL stream to stdout which can then be passed to restore later.
This may be helpful in some normal situations, and will allow C/R to
migrate the routing information in userspace.  Tweaking of the stream
can be done by userspace helpers to convert between versions and adjust
things like device indexes when restoring routes in a different
environment.

By factoring out some of the common bits of print_route() into
filter_nlmsg(), the "save" command can use the same selection logic
as "list," allowing the caller to save only specific routes as
necessary.

The only change since the RFC is the addition of manpage and doc
material.

Signed-off-by: Dan Smith <danms@us.ibm.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/doc/ip-cref.tex b/doc/ip-cref.tex
index 056e3bf5..d8fed66e 100644
--- a/doc/ip-cref.tex
+++ b/doc/ip-cref.tex
@@ -1675,6 +1675,41 @@ information about this route is shown:
 \item \verb|used| --- the number of lookups of this route since its creation.
 \end{itemize}
 
+\subsection{{\tt ip route save} -- save routing tables}
+\label{IP-ROUTE-SAVE}
+
+\paragraph{Description:} this command saves the contents of the routing
+tables or the route(s) selected by some criteria to standard output.
+
+\paragraph{Arguments:} \verb|ip route save| has the same arguments as
+\verb|ip route show|.
+
+\paragraph{Example:} This saves all the routes to the {\tt saved\_routes}
+file:
+\begin{verbatim}
+dan@caffeine:~ # ip route save > saved_routes
+\end{verbatim}
+
+\paragraph{Output format:} The format of the data stream provided by
+\verb|ip route save| is that of \verb|rtnetlink|.  See
+\verb|rtnetlink(7)| for more information.
+
+\subsection{{\tt ip route restore} -- restore routing tables}
+\label{IP-ROUTE-RESTORE}
+
+\paragraph{Description:} this command restores the contents of the routing
+tables according to a data stream as provided by \verb|ip route save| via
+standard input.  Note that any routes already in the table are left unchanged.
+Any routes in the input stream that already exist in the tables are ignored.
+
+\paragraph{Arguments:} This command takes no arguments.
+
+\paragraph{Example:} This restores all routes that were saved to the
+{\tt saved\_routes} file:
+
+\begin{verbatim}
+dan@caffeine:~ # ip route restore < saved_routes
+\end{verbatim}
 
 \subsection{{\tt ip route flush} --- flush routing tables}
 \label{IP-ROUTE-FLUSH}