In sppp(4), allow additional 'wildcard' addresses for the destination.

Any address within the range 0.0.0.1 - 0.0.0.255 can now be used.
This allows for multiple pppoe(4) interfaces with dynamic addresses within
the same routing table. Which used to work before OpenBSD 5.8, but since 5.8
only one interface in a routing table can use destination address 0.0.0.1.

Problem first reported by Steve (fiverings04 at australian yahoo) on misc@.
I ran into it on an EdgeRouter lite which is supposed to serve two ADSL lines.
ok sthen@ mpi@
man page help from jmc@ for an earlier variant of this change

1 files changed, 19 insertions, 12 deletions

diff --git a/share/man/man4/pppoe.4 b/share/man/man4/pppoe.4
index 3a426710385..a6af9e09005 100644
--- a/share/man/man4/pppoe.4
+++ b/share/man/man4/pppoe.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: pppoe.4,v 1.33 2017/03/22 21:37:24 jmc Exp $
+.\"	$OpenBSD: pppoe.4,v 1.34 2017/06/16 10:58:43 stsp Exp $
 .\"	$NetBSD: pppoe.4,v 1.26 2003/10/02 07:06:36 wiz Exp $
 .\"
 .\" Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -28,7 +28,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: March 22 2017 $
+.Dd $Mdocdate: June 16 2017 $
 .Dt PPPOE 4
 .Os
 .Sh NAME
@@ -113,17 +113,19 @@ The physical interface must also be marked
 .Pp
 Since this is a PPP interface, the addresses assigned to the interface
 may change during PPP negotiation.
-There is no fine grained control available for deciding
-which addresses are acceptable and which are not.
-For the local side and the remote address there is exactly one choice:
-hard coded address or wildcard.
-If a real address is assigned to one side of the connection,
-PPP negotiation will only agree to exactly this address.
-If one side is wildcarded,
-every address suggested by the peer will be accepted.
+In the above example, 0.0.0.0 and 0.0.0.1 serve as placeholders for
+dynamic address configuration.
 .Pp
-To wildcard the local address set it to 0.0.0.0; to wildcard the remote
-address set it to 0.0.0.1.
+If the local address is set to wildcard address 0.0.0.0, it will
+be changed to an address suggested by the peer.
+.Pp
+If the destination address is set to a wildcard address in the range
+from 0.0.0.1 to 0.0.0.255, it will be changed to an address suggested
+by the peer, and if a default route which uses this interface exists
+the gateway will be changed to the suggested address as well.
+.Pp
+Otherwise, PPP negotiation will only agree to exactly the IPv4 addresses
+which are configured on the interface.
 .Sh KERNEL OPTIONS
 .Nm
 does not interfere with other PPPoE implementations
@@ -254,3 +256,8 @@ The presence of a
 .Xr mygate 5
 file will interfere with the routing table.
 Make sure this file is either empty or does not exist.
+.Pp
+Two
+.Nm
+interfaces configured with the same wildcard destination address
+cannot share a routing table.