From 345236211715ffb7cc28f6ff0b26acb90181e738 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Fri, 26 Aug 2016 18:00:00 +0200 Subject: 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 --- tests/py/ip/hash.t | 5 +++++ tests/py/ip/hash.t.payload | 17 +++++++++++++++++ 2 files changed, 22 insertions(+) create mode 100644 tests/py/ip/hash.t create mode 100644 tests/py/ip/hash.t.payload (limited to 'tests') 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 ] + -- cgit v1.2.3