IKEv2 test using IPCOMP

The IPCOMP ip xfrm output is a little odd. It contains proto esp, proto comp
and proto 4 (ipip) entries. It also changes the outer ESP as transport mode,
even if it is really tunnel mode.

We test with compressable pings to see the counter on the ipcomp SA increase,
but one the counters always increases even if packets were not compressed.

[root@west ~]# ip xfrm state
src 192.1.2.23 dst 192.1.2.45
	proto esp spi 0xe1c4db39 reqid 16389 mode transport
	replay-window 32 
	auth-trunc hmac(sha1) 0xf5e3f7b95e50702f0f116859218d117ab617d1e7 96
	enc cbc(aes) 0x0604237096a2f5bb32b42b057471582649a3cc003685aad9af3aa9c8f9d640e5
	anti-replay context: seq 0x8, oseq 0x0, bitmap 0x000000ff
	sel src 0.0.0.0/0 dst 0.0.0.0/0 
src 192.1.2.23 dst 192.1.2.45
	proto comp spi 0x0000a833 reqid 16390 mode tunnel
	replay-window 0 flag af-unspec
	comp deflate 
	anti-replay context: seq 0x0, oseq 0x0, bitmap 0x00000000
src 192.1.2.23 dst 192.1.2.45
	proto 4 spi 0xc0010217 reqid 0 mode tunnel
	replay-window 0 flag af-unspec
	anti-replay context: seq 0x0, oseq 0x0, bitmap 0x00000000
src 192.1.2.45 dst 192.1.2.23
	proto esp spi 0xc1697bd5 reqid 16389 mode transport
	replay-window 32 
	auth-trunc hmac(sha1) 0x26fed381a54de6e3e72646f7918c5e5c41f59751 96
	enc cbc(aes) 0x47a49b7ad03a69d2756de74efa0dd13e2df6340a9a3b78fb3f04caf183141f95
	anti-replay context: seq 0x0, oseq 0x8, bitmap 0x00000000
	sel src 0.0.0.0/0 dst 0.0.0.0/0 
src 192.1.2.45 dst 192.1.2.23
	proto comp spi 0x00003142 reqid 16390 mode tunnel
	replay-window 0 flag af-unspec
	comp deflate 
	anti-replay context: seq 0x0, oseq 0x0, bitmap 0x00000000
src 192.1.2.45 dst 192.1.2.23
	proto 4 spi 0xc001022d reqid 0 mode tunnel
	replay-window 0 flag af-unspec
	anti-replay context: seq 0x0, oseq 0x0, bitmap 0x00000000

Similarly, policy looks a little odd with mixup of tunnel/transport

[root@west ~]# ip xfrm pol
src 192.0.1.0/24 dst 192.0.2.0/24 
	dir out priority 1042407 ptype main 
	tmpl src 192.1.2.45 dst 192.1.2.23
		proto comp reqid 16390 mode tunnel
	tmpl src 0.0.0.0 dst 0.0.0.0
		proto esp reqid 16389 mode transport
src 192.0.2.0/24 dst 192.0.1.0/24 
	dir fwd priority 1042407 ptype main 
	tmpl src 192.1.2.23 dst 192.1.2.45
		proto comp reqid 16390 mode tunnel
		level use 
	tmpl src 0.0.0.0 dst 0.0.0.0
		proto esp reqid 16389 mode transport
src 192.0.2.0/24 dst 192.0.1.0/24 
	dir in priority 1042407 ptype main 
	tmpl src 192.1.2.23 dst 192.1.2.45
		proto comp reqid 16390 mode tunnel
		level use 
	tmpl src 0.0.0.0 dst 0.0.0.0
		proto esp reqid 16389 mode transport