src: hash: support of symmetric hash

This patch provides symmetric hash support according to source
ip address and port, and destination ip address and port.

The new attribute NFTA_HASH_TYPE has been included to support
different types of hashing functions. Currently supported
NFT_HASH_JENKINS through jhash and NFT_HASH_SYM through symhash.

The main difference between both types are:
 - jhash requires an expression with sreg, symhash doesn't.
 - symhash supports modulus and offset, but not seed.

Examples:

 nft add rule ip nat prerouting ct mark set jhash ip saddr mod 2
 nft add rule ip nat prerouting ct mark set symhash mod 2

Signed-off-by: Laura Garcia Liebana <laura.garcia@zevenet.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/scanner.l b/src/scanner.l
index b70e1a80..003f15eb 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -488,6 +488,7 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 "offset"		{ return OFFSET; }
 
 "jhash"			{ return JHASH; }
+"symhash"		{ return SYMHASH; }
 "seed"			{ return SEED; }
 
 "dup"			{ return DUP; }