Короче, вот что я с подсистемой MPLS в Linux сделал:
root@ne-vlezay80:/usr/src/linux-4.10.9# cat net/mpls/internal.h
#ifndef MPLS_INTERNAL_H
#define MPLS_INTERNAL_H
#include <net/mpls.h>
struct mpls_entry_decoded {
u32 label;
u8 ttl;
u8 tc;
u8 bos;
};
struct mpls_dev {
int input_enabled;
struct ctl_table_header *sysctl;
struct rcu_head rcu;
};
struct sk_buff;
#define LABEL_NOT_SPECIFIED (1 << 20)
#define MAX_NEW_LABELS 512
/* This maximum ha length copied from the definition of struct neighbour */
#define VIA_ALEN_ALIGN sizeof(unsigned long)
#define MAX_VIA_ALEN (ALIGN(MAX_ADDR_LEN, VIA_ALEN_ALIGN))
enum mpls_payload_type {
MPT_UNSPEC, /* IPv4 or IPv6 */
MPT_IPV4 = 4,
MPT_IPV6 = 6,
/* Other types not implemented:
* - Pseudo-wire with or without control word (RFC4385)
* - GAL (RFC5586)
*/
};
struct mpls_nh { /* next hop label forwarding entry */
struct net_device __rcu *nh_dev;
unsigned int nh_flags;
u32 nh_label[MAX_NEW_LABELS];
u8 nh_labels;
u8 nh_via_alen;
u8 nh_via_table;
};
/* The route, nexthops and vias are stored together in the same memory
* block:
*
* +----------------------+
* | mpls_route |
* +----------------------+
* | mpls_nh 0 |
* +----------------------+
* | ... |
* +----------------------+
* | mpls_nh n-1 |
* +----------------------+
* | alignment padding |
* +----------------------+
* | via[rt_max_alen] 0 |
* +----------------------+
* | ... |
* +----------------------+
* | via[rt_max_alen] n-1 |
* +----------------------+
*/
struct mpls_route { /* next hop label forwarding entry */
struct rcu_head rt_rcu;
u8 rt_protocol;
u8 rt_payload_type;
u8 rt_max_alen;
unsigned int rt_nhn;
unsigned int rt_nhn_alive;
struct mpls_nh rt_nh[0];
};
#define for_nexthops(rt) { \
int nhsel; struct mpls_nh *nh; \
for (nhsel = 0, nh = (rt)->rt_nh; \
nhsel < (rt)->rt_nhn; \
nh++, nhsel++)
#define change_nexthops(rt) { \
int nhsel; struct mpls_nh *nh; \
for (nhsel = 0, nh = (struct mpls_nh *)((rt)->rt_nh); \
nhsel < (rt)->rt_nhn; \
nh++, nhsel++)
#define endfor_nexthops(rt) }
static inline struct mpls_shim_hdr mpls_entry_encode(u32 label, unsigned ttl, unsigned tc, bool bos)
{
struct mpls_shim_hdr result;
result.label_stack_entry =
cpu_to_be32((label << MPLS_LS_LABEL_SHIFT) |
(tc << MPLS_LS_TC_SHIFT) |
(bos ? (1 << MPLS_LS_S_SHIFT) : 0) |
(ttl << MPLS_LS_TTL_SHIFT));
return result;
}
static inline struct mpls_entry_decoded mpls_entry_decode(struct mpls_shim_hdr *hdr)
{
struct mpls_entry_decoded result;
unsigned entry = be32_to_cpu(hdr->label_stack_entry);
result.label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT;
result.ttl = (entry & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
result.tc = (entry & MPLS_LS_TC_MASK) >> MPLS_LS_TC_SHIFT;
result.bos = (entry & MPLS_LS_S_MASK) >> MPLS_LS_S_SHIFT;
return result;
}
int nla_put_labels(struct sk_buff *skb, int attrtype, u8 labels,
const u32 label[]);
int nla_get_labels(const struct nlattr *nla, u32 max_labels, u8 *labels,
u32 label[]);
int nla_get_via(const struct nlattr *nla, u8 *via_alen, u8 *via_table,
u8 via[]);
bool mpls_output_possible(const struct net_device *dev);
unsigned int mpls_dev_mtu(const struct net_device *dev);
bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu);
#endif /* MPLS_INTERNAL_H */
#define MAX_NEW_LABELS 512
root@ne-vlezay80:/usr/src/linux-4.10.9# ip r
default via 10.247.0.1 dev ic-br0 proto zebra metric 20
10.10.10.1 encap mpls 100/101/102/104/105/106/107/108 via 10.247.0.1 dev ic-br0
...
root@servl:~# tcpdump -i br-vlan0 -n -p mpls
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on br-vlan0, link-type EN10MB (Ethernet), capture size 262144 bytes
01:07:35.531201 MPLS (label 100, exp 0, ttl 64) (label 101, exp 0, ttl 64) (label 102, exp 0, ttl 64) (label 104, exp 0, ttl 64) (label 105, exp 0, ttl 64) (label 106, exp 0, ttl 64) (label 107, exp 0, ttl 64) (label 108, exp 0, [S], ttl 64) IP 10.247.0.250 > 10.10.10.1: ICMP echo request, id 1508, seq 5, length 64
^C
1 packet captured
1 packet received by filter
0 packets dropped by kernel
