.\" $OpenBSD: rtalloc.9,v 1.12 2019/07/12 16:53:57 mpi Exp $
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.\" Copyright (c) 2014-2015 Martin Pieuchot
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.Dd $Mdocdate: July 12 2019 $
.Dt RTALLOC 9
.Os
.Sh NAME
.Nm rtalloc ,
.Nm rtalloc_mpath ,
.Nm rtisvalid ,
.Nm rtref ,
.Nm rtfree
.Nd routing entry interface
.Sh SYNOPSIS
.In sys/types.h
.In sys/socket.h
.In net/route.h
.Ft struct rtentry *
.Fn rtalloc "struct sockaddr *dst" "int flags" "unsigned int rtableid"
.Ft struct rtentry *
.Fn rtalloc_mpath "struct sockaddr *dst" "uint32_t *src" "unsigned int rtableid"
.Ft int
.Fn rtisvalid "struct rtentry *rt"
.Ft void
.Fn rtref "struct rtentry *rt"
.Ft void
.Fn rtfree "struct rtentry *rt"
.Sh DESCRIPTION
The
.Fn rtalloc
function looks in the routing table
.Fa rtableid
for an entry matching
.Fa dst .
The following
.Fa flags
can be specified:
.Bl -tag -width RT_RESOLVE -offset indent
.It Dv RT_RESOLVE
Allocate and return a cloned entry for
.Fa dst
if it does not exist and the lookup returned a cloning entry.
.El
.Pp
The
.Fn rtalloc_mpath
function does the same as
.Fn rtalloc
with the
.Dv RT_RESOLVE
.Fa flag ,
but selects a multipath routing entry corresponding to
.Fa src
when possible.
.Pp
The
.Fn rtisvalid
function checks if the route entry
.Fa rt
is still valid and can be used.
Cached entries that are no longer valid should be released by calling
.Fn rtfree .
.Pp
The
.Fn rtref
function increments a reference to the routing entry
.Fa rt .
.Pp
The
.Fn rtfree
function releases a reference to the routing entry
.Fa rt ,
freeing it if the reference count drops to 0.
If
.Fa rt
is a
.Dv NULL
pointer, no action occurs.
.Sh CONTEXT
.Fn rtalloc ,
.Fn rtalloc_mpath ,
.Fn rtisvalid ,
.Fn rtref ,
and
.Fn rtfree
can be called during autoconf, from process context, or from interrupt context.
.Sh RETURN VALUES
.Fn rtisvalid
returns 1 if the route entry is valid, otherwise 0.
.Sh SEE ALSO
.Xr route 4 ,
.Xr rtable_walk 9 ,
.Xr rtrequest 9