diff options
| 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 /include | |
| 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 'include')
| -rw-r--r-- | include/expression.h | 9 | ||||
| -rw-r--r-- | include/hash.h | 7 |
2 files changed, 16 insertions, 0 deletions
diff --git a/include/expression.h b/include/expression.h index b6005ec3..6a509b33 100644 --- a/include/expression.h +++ b/include/expression.h @@ -34,6 +34,7 @@ * @EXPR_BINOP: binary operations (bitwise, shifts) * @EXPR_RELATIONAL: equality and relational expressions * @EXPR_NUMGEN: number generation expression + * @EXPR_HASH: hash expression */ enum expr_types { EXPR_INVALID, @@ -57,6 +58,7 @@ enum expr_types { EXPR_BINOP, EXPR_RELATIONAL, EXPR_NUMGEN, + EXPR_HASH, }; enum ops { @@ -174,6 +176,7 @@ enum expr_flags { #include <exthdr.h> #include <numgen.h> #include <meta.h> +#include <hash.h> #include <ct.h> /** @@ -285,6 +288,12 @@ struct expr { enum nft_ng_types type; uint32_t mod; } numgen; + struct { + /* EXPR_HASH */ + struct expr *expr; + uint32_t mod; + uint32_t seed; + } hash; }; }; diff --git a/include/hash.h b/include/hash.h new file mode 100644 index 00000000..bc8c86af --- /dev/null +++ b/include/hash.h @@ -0,0 +1,7 @@ +#ifndef NFTABLES_HASH_H +#define NFTABLES_HASH_H + +extern struct expr *hash_expr_alloc(const struct location *loc, + uint32_t modulus, uint32_t seed); + +#endif /* NFTABLES_HASH_H */ |