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 /src/parser_bison.y | |
| 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 'src/parser_bison.y')
| -rw-r--r-- | src/parser_bison.y | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/src/parser_bison.y b/src/parser_bison.y index 23e8b275..dc794656 100644 --- a/src/parser_bison.y +++ b/src/parser_bison.y @@ -411,6 +411,9 @@ static void location_update(struct location *loc, struct location *rhs, int n) %token INC "inc" %token MOD "mod" +%token JHASH "jhash" +%token SEED "seed" + %token POSITION "position" %token COMMENT "comment" @@ -556,8 +559,8 @@ static void location_update(struct location *loc, struct location *rhs, int n) %type <expr> arp_hdr_expr %destructor { expr_free($$); } arp_hdr_expr %type <val> arp_hdr_field -%type <expr> ip_hdr_expr icmp_hdr_expr numgen_expr -%destructor { expr_free($$); } ip_hdr_expr icmp_hdr_expr numgen_expr +%type <expr> ip_hdr_expr icmp_hdr_expr numgen_expr hash_expr +%destructor { expr_free($$); } ip_hdr_expr icmp_hdr_expr numgen_expr hash_expr %type <val> ip_hdr_field icmp_hdr_field %type <expr> ip6_hdr_expr icmp6_hdr_expr %destructor { expr_free($$); } ip6_hdr_expr icmp6_hdr_expr @@ -1972,6 +1975,7 @@ primary_expr : symbol_expr { $$ = $1; } | meta_expr { $$ = $1; } | ct_expr { $$ = $1; } | numgen_expr { $$ = $1; } + | hash_expr { $$ = $1; } | '(' basic_expr ')' { $$ = $2; } ; @@ -2469,6 +2473,13 @@ numgen_expr : NUMGEN numgen_type MOD NUM } ; +hash_expr : JHASH expr MOD NUM SEED NUM + { + $$ = hash_expr_alloc(&@$, $4, $6); + $$->hash.expr = $2; + } + ; + ct_expr : CT ct_key { $$ = ct_expr_alloc(&@$, $2, -1); |