This patch corresponds to a Linux kernel patch extending the kernel GTP
to also cover the SGSN role, not just the GGSN role. In order to keep
the API/behavior compatible, gtp_dev_create() will continue to create
GGSN-side tunnels, while a new gtp_dev_create_sgsn() is introduced to
create SGSN-side tunnels.
Signed-off-by: Harald Welte <laforge@gnumonks.org>
We can use this to specify 'gtp0' from openggsn, so we make sure that
it always uses the same tunnel device on creation. If it already exists,
it will return EEXIST. This is used to skip the problem of lacking
NLM_F_ECHO in the rtnetlink link interface that allows us to know the
name of the gtp device that has been dynamically allocated from the
kernel.
And, finally, I don't find any use case for having more than one tunnel
device when integrating this with openggsn.
This patch also adjusts tools/gtp-link-add.c which needs some care, since
it is not yet using any of the library functions. This tools are likely
to be useful for troubleshooting and debugging.
openggsn already sets up the UDP sockets that we need for the control
and user planes of GTP. Since we cannot bind two UDP sockets (one from
userspace and another from the kernel) to the same port, change the
current code to pass the socket descriptors that has been allocated
by openggsn (or whatever daemon which uses the GTP kernel
infrastructure).
Two new attributes are added to set up the tunnel device: IFLA_GTP_FD0
(for GTP0) and IFLA_GTP_FD1 (for GTP1u), which specify the UDP socket
created from userspace. Thus, the GTP kernel code only takes care of
enabling the kernel UDP encapsulation routine.
This patch adds a gtp_tunnel structure to avoid having to deal with
functions with lots of parameters. This should also help to extend
the interfaces and the gtp_tunnel object without breaking the binary
interface (which will be good by when ipv6 support will be added).
This patch adds the libgtpnl library. Harald mentioned that he wanted
that the specific code that is added is well encapsulated, so let's
start a small library to interact with the GTP kernel module via netlink
interface.
This was done a bit while in the rush, so the interfaces are not nice
at all and the tools need to be ported on top of this library.
This library will be used to integrate openggsn with the GTP kernel
module.
Harald Welte
Andreas Schultz