Re: IP/UDP encapsulation

[Eric Dumazet <eric.dumazet@gmail.com>]

Le jeudi 08 avril 2010 à 04:42 -0300, Gustavo F. Padovan a écrit :
> Hi,
> 
> I'm looking for some advice on that work. The Freifunk organization is
> planning work on the IP/UDP encapsulation kernel module as a GSoC
> project. The idea is to create a IP-in-UDP tunnel like we do for
> IP-in-IP or IP-in-GRE tunnels. The only way to do that today is to use
> some VPN software.
> 
> The module will export its virtual interface through sockets and will
> have support for the standard syscalls like the others encapsulation
> modules.
> 
> It will improve the performance of mesh networks that will we be able
> to use IP-in-UDP rather than IP-in-IP. So, instead of push all data to
> local gateway into the mesh all the data can be tunneled to a faster
> server and from there to the Internet. With all the data exiting with
> the same IP address (the fast server IP). That will improve bandwidth,
> especially for upload.
> 
> Is such module acceptable for merge into the Linux Kernel?
> 
> Any comments or suggestions to the module architecture and
> implementation? If you want more information about the module I can
> provide that.
> 
> Regards,
> 

My suggestion would be to take a look at l2tp, which uses udp
encapsulation.

net-next-2.6

net/l2tp/l2tp_core.c:1108:		(udp_sk(sk))->encap_type = 0;
net/l2tp/l2tp_core.c:1304:	enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
net/l2tp/l2tp_core.c:1383:		udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
net/l2tp/l2tp_core.h:148:	enum l2tp_encap_type	encap;
net/l2tp/l2tp_core.h:171:	enum l2tp_encap_type	encap;
net/ipv4/udp.c:1299:	if (up->encap_type) {
net/ipv4/udp.c:1660:			up->encap_type = val;
net/ipv4/udp.c:1747:		val = up->encap_type;
include/linux/l2tp.h:81:	L2TP_ATTR_ENCAP_TYPE,		/* u16, enum l2tp_encap_type */
include/linux/l2tp.h:146:enum l2tp_encap_type {
include/linux/udp.h:63:  	__u16		 encap_type;	/* Is this an Encapsulation socket? */