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| author | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-08-26 18:00:00 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-08-29 20:30:29 +0200 |
| commit | 345236211715ffb7cc28f6ff0b26acb90181e738 (patch) | |
| tree | aebfc9aeece1dda1bb1ffab52aa93a9b1114f928 /tests/py/ip | |
| parent | 13eeed6ea6f0a5d1353ee5ad14c4322695b4f59b (diff) | |
src: add hash expression
This is special expression that transforms an input expression into a
32-bit unsigned integer. This expression takes a modulus parameter to
scale the result and the random seed so the hash result becomes harder
to predict.
You can use it to set the packet mark, eg.
# nft add rule x y meta mark set jhash ip saddr . ip daddr mod 2 seed 0xdeadbeef
You can combine this with maps too, eg.
# nft add rule x y dnat to jhash ip saddr mod 2 seed 0xdeadbeef map { \
0 : 192.168.20.100, \
1 : 192.168.30.100 \
}
Currently, this expression implements the jenkins hash implementation
available in the Linux kernel:
http://lxr.free-electrons.com/source/include/linux/jhash.h
But it should be possible to extend it to support any other hash
function type.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'tests/py/ip')
| -rw-r--r-- | tests/py/ip/hash.t | 5 | ||||
| -rw-r--r-- | tests/py/ip/hash.t.payload | 17 |
2 files changed, 22 insertions, 0 deletions
diff --git a/tests/py/ip/hash.t b/tests/py/ip/hash.t new file mode 100644 index 00000000..6dfa965b --- /dev/null +++ b/tests/py/ip/hash.t @@ -0,0 +1,5 @@ +:pre;type nat hook prerouting priority 0 +*ip;test-ip4;pre + +ct mark set jhash ip saddr . ip daddr mod 2 seed 0xdeadbeef;ok +dnat to jhash ip saddr mod 2 seed 0xdeadbeef map { 0 : 192.168.20.100, 1 : 192.168.30.100 };ok diff --git a/tests/py/ip/hash.t.payload b/tests/py/ip/hash.t.payload new file mode 100644 index 00000000..429e2b76 --- /dev/null +++ b/tests/py/ip/hash.t.payload @@ -0,0 +1,17 @@ +# ct mark set jhash ip saddr . ip daddr mod 2 seed 0xdeadbeef +ip test-ip4 pre + [ payload load 4b @ network header + 12 => reg 2 ] + [ payload load 4b @ network header + 16 => reg 13 ] + [ hash reg 1 = jhash(reg 2, 8, 3735928559) % modulus 2] + [ ct set mark with reg 1 ] + +# dnat to jhash ip saddr mod 2 seed 0xdeadbeef map { 0 : 192.168.20.100, 1 : 192.168.30.100 } +__map%d test-ip4 b +__map%d test-ip4 0 + element 00000000 : 6414a8c0 0 [end] element 01000000 : 641ea8c0 0 [end] +ip test-ip4 pre + [ payload load 4b @ network header + 12 => reg 2 ] + [ hash reg 1 = jhash(reg 2, 4, 3735928559) % modulus 2] + [ lookup reg 1 set __map%d dreg 1 ] + [ nat dnat ip addr_min reg 1 addr_max reg 0 ] + |