nft: cache: Fetch cache for specific chains

Iterate over command list and collect chains to cache. Insert them into
a sorted list to pass to __nft_build_cache().

If a command is interested in all chains (e.g., --list), cmd->chain
remains unset. To record this case reliably, use a boolean
('all_chains'). Otherwise, it is hard to distinguish between first call
to nft_cache_level_set() and previous command with NULL cmd->chain
value.

When caching only specific chains, manually add builtin ones for the
given table as well - otherwise nft_xt_builtin_init() will act as if
they don't exist and possibly override non-default chain policies.

Signed-off-by: Phil Sutter <phil@nwl.cc>

1 files changed, 7 insertions, 0 deletions

diff --git a/iptables/nft.h b/iptables/nft.h
index 4eaaa77f..aeacc608 100644
--- a/iptables/nft.h
+++ b/iptables/nft.h
@@ -71,9 +71,16 @@ enum obj_update_type {
 	NFT_COMPAT_TABLE_NEW,
 };
 
+struct cache_chain {
+	struct list_head head;
+	char *name;
+};
+
 struct nft_cache_req {
 	enum nft_cache_level	level;
 	char			*table;
+	bool			all_chains;
+	struct list_head	chain_list;
 };
 
 struct nft_handle {