src: add last statement

This new statement allows you to know how long ago there was a matching
packet.

 # nft list ruleset
 table ip x {
        chain y {
		[...]
                ip protocol icmp last used 49m54s884ms counter packets 1 bytes 64
	}
 }

if this statement never sees a packet, then the listing says:

 ip protocol icmp last used never counter packets 0 bytes 0

Add tests/py in this patch too.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

6 files changed, 102 insertions, 3 deletions

diff --git a/src/evaluate.c b/src/evaluate.c
index 19faf621..47caf3b0 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -4280,6 +4280,7 @@ int stmt_evaluate(struct eval_ctx *ctx, struct stmt *stmt)
 	switch (stmt->ops->type) {
 	case STMT_CONNLIMIT:
 	case STMT_COUNTER:
+	case STMT_LAST:
 	case STMT_LIMIT:
 	case STMT_QUOTA:
 	case STMT_NOTRACK:
diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
index 00221505..60350cd6 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -1067,6 +1067,19 @@ static void netlink_parse_counter(struct netlink_parse_ctx *ctx,
 	ctx->stmt = stmt;
 }
 
+static void netlink_parse_last(struct netlink_parse_ctx *ctx,
+			       const struct location *loc,
+			       const struct nftnl_expr *nle)
+{
+	struct stmt *stmt;
+
+	stmt = last_stmt_alloc(loc);
+	stmt->last.used = nftnl_expr_get_u64(nle, NFTNL_EXPR_LAST_MSECS);
+	stmt->last.set = nftnl_expr_get_u32(nle, NFTNL_EXPR_LAST_SET);
+
+	ctx->stmt = stmt;
+}
+
 static void netlink_parse_log(struct netlink_parse_ctx *ctx,
 			      const struct location *loc,
 			      const struct nftnl_expr *nle)
@@ -1877,6 +1890,7 @@ static const struct expr_handler netlink_parsers[] = {
 	{ .name = "ct",		.parse = netlink_parse_ct },
 	{ .name = "connlimit",	.parse = netlink_parse_connlimit },
 	{ .name = "counter",	.parse = netlink_parse_counter },
+	{ .name = "last",	.parse = netlink_parse_last },
 	{ .name = "log",	.parse = netlink_parse_log },
 	{ .name = "limit",	.parse = netlink_parse_limit },
 	{ .name = "range",	.parse = netlink_parse_range },
diff --git a/src/netlink_linearize.c b/src/netlink_linearize.c
index 3da72f50..11cf48a3 100644
--- a/src/netlink_linearize.c
+++ b/src/netlink_linearize.c
@@ -1001,6 +1001,17 @@ static struct nftnl_expr *netlink_gen_quota_stmt(const struct stmt *stmt)
 	return nle;
 }
 
+static struct nftnl_expr *netlink_gen_last_stmt(const struct stmt *stmt)
+{
+	struct nftnl_expr *nle;
+
+	nle = alloc_nft_expr("last");
+	nftnl_expr_set_u32(nle, NFTNL_EXPR_LAST_SET, stmt->last.set);
+	nftnl_expr_set_u64(nle, NFTNL_EXPR_LAST_MSECS, stmt->last.used);
+
+	return nle;
+}
+
 struct nftnl_expr *netlink_gen_stmt_stateful(const struct stmt *stmt)
 {
 	switch (stmt->ops->type) {
@@ -1012,6 +1023,8 @@ struct nftnl_expr *netlink_gen_stmt_stateful(const struct stmt *stmt)
 		return netlink_gen_limit_stmt(stmt);
 	case STMT_QUOTA:
 		return netlink_gen_quota_stmt(stmt);
+	case STMT_LAST:
+		return netlink_gen_last_stmt(stmt);
 	default:
 		BUG("unknown stateful statement type %s\n", stmt->ops->name);
 	}
@@ -1687,6 +1700,7 @@ static void netlink_gen_stmt(struct netlink_linearize_ctx *ctx,
 	case STMT_COUNTER:
 	case STMT_LIMIT:
 	case STMT_QUOTA:
+	case STMT_LAST:
 		nle = netlink_gen_stmt_stateful(stmt);
 		nft_rule_add_expr(ctx, nle, &stmt->location);
 		break;
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 824e5db8..b950afce 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -554,6 +554,9 @@ int nft_lex(void *, void *, void *);
 %token BYTES			"bytes"
 %token AVGPKT			"avgpkt"
 
+%token LAST			"last"
+%token NEVER			"never"
+
 %token COUNTERS			"counters"
 %token QUOTAS			"quotas"
 %token LIMITS			"limits"
@@ -710,8 +713,8 @@ int nft_lex(void *, void *, void *);
 %destructor { stmt_list_free($$); xfree($$); } stmt_list stateful_stmt_list set_elem_stmt_list
 %type <stmt>			stmt match_stmt verdict_stmt set_elem_stmt
 %destructor { stmt_free($$); }	stmt match_stmt verdict_stmt set_elem_stmt
-%type <stmt>			counter_stmt counter_stmt_alloc stateful_stmt
-%destructor { stmt_free($$); }	counter_stmt counter_stmt_alloc stateful_stmt
+%type <stmt>			counter_stmt counter_stmt_alloc stateful_stmt last_stmt
+%destructor { stmt_free($$); }	counter_stmt counter_stmt_alloc stateful_stmt last_stmt
 %type <stmt>			payload_stmt
 %destructor { stmt_free($$); }	payload_stmt
 %type <stmt>			ct_stmt
@@ -968,6 +971,7 @@ close_scope_at		: { scanner_pop_start_cond(nft->scanner, PARSER_SC_AT); };
 close_scope_comp	: { scanner_pop_start_cond(nft->scanner, PARSER_SC_EXPR_COMP); };
 close_scope_ct		: { scanner_pop_start_cond(nft->scanner, PARSER_SC_CT); };
 close_scope_counter	: { scanner_pop_start_cond(nft->scanner, PARSER_SC_COUNTER); };
+close_scope_last	: { scanner_pop_start_cond(nft->scanner, PARSER_SC_LAST); };
 close_scope_dccp	: { scanner_pop_start_cond(nft->scanner, PARSER_SC_EXPR_DCCP); };
 close_scope_destroy	: { scanner_pop_start_cond(nft->scanner, PARSER_SC_CMD_DESTROY); };
 close_scope_dst		: { scanner_pop_start_cond(nft->scanner, PARSER_SC_EXPR_DST); };
@@ -2686,6 +2690,7 @@ chain_policy		:	ACCEPT		{ $$ = NF_ACCEPT; }
 			;
 
 identifier		:	STRING
+			|	LAST		{ $$ = xstrdup("last"); }
 			;
 
 string			:	STRING
@@ -2966,6 +2971,7 @@ stateful_stmt		:	counter_stmt	close_scope_counter
 			|	limit_stmt
 			|	quota_stmt
 			|	connlimit_stmt
+			|	last_stmt	close_scope_last
 			;
 
 stmt			:	verdict_stmt
@@ -3104,6 +3110,22 @@ counter_arg		:	PACKETS			NUM
 			}
 			;
 
+last_stmt		:	LAST
+			{
+				$$ = last_stmt_alloc(&@$);
+			}
+			|	LAST USED	NEVER
+			{
+				$$ = last_stmt_alloc(&@$);
+			}
+			|	LAST USED	time_spec
+			{
+				$$ = last_stmt_alloc(&@$);
+				$$->last.used = $3;
+				$$->last.set = true;
+			}
+			;
+
 log_stmt		:	log_stmt_alloc
 			|	log_stmt_alloc		log_args
 			;
@@ -4530,6 +4552,16 @@ set_elem_stmt		:	COUNTER	close_scope_counter
 				$$->connlimit.count = $4;
 				$$->connlimit.flags = NFT_CONNLIMIT_F_INV;
 			}
+			|	LAST USED	NEVER	close_scope_last
+			{
+				$$ = last_stmt_alloc(&@$);
+			}
+			|	LAST USED	time_spec	close_scope_last
+			{
+				$$ = last_stmt_alloc(&@$);
+				$$->last.used = $3;
+				$$->last.set = true;
+			}
 			;
 
 set_elem_expr_option	:	TIMEOUT			time_spec
@@ -4917,6 +4949,7 @@ keyword_expr		:	ETHER   close_scope_eth { $$ = symbol_value(&@$, "ether"); }
 			|	ORIGINAL		{ $$ = symbol_value(&@$, "original"); }
 			|	REPLY			{ $$ = symbol_value(&@$, "reply"); }
 			|	LABEL			{ $$ = symbol_value(&@$, "label"); }
+			|	LAST	close_scope_last	{ $$ = symbol_value(&@$, "last"); }
 			;
 
 primary_rhs_expr	:	symbol_expr		{ $$ = $1; }
diff --git a/src/scanner.l b/src/scanner.l
index bc5b5b62..15ca3d46 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -206,6 +206,7 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 %s SCANSTATE_IGMP
 %s SCANSTATE_IP
 %s SCANSTATE_IP6
+%s SCANSTATE_LAST
 %s SCANSTATE_LIMIT
 %s SCANSTATE_META
 %s SCANSTATE_POLICY
@@ -402,6 +403,11 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 <SCANSTATE_COUNTER,SCANSTATE_CT,SCANSTATE_LIMIT>"packets"		{ return PACKETS; }
 <SCANSTATE_COUNTER,SCANSTATE_CT,SCANSTATE_LIMIT,SCANSTATE_QUOTA>"bytes"	{ return BYTES; }
 
+"last"				{ scanner_push_start_cond(yyscanner, SCANSTATE_LAST); return LAST; }
+<SCANSTATE_LAST>{
+	"never"			{ return NEVER; }
+}
+
 <SCANSTATE_CMD_LIST,SCANSTATE_CMD_RESET>{
 	"counters"		{ return COUNTERS; }
 	"quotas"		{ return QUOTAS; }
@@ -437,10 +443,11 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 
 "quota"			{ scanner_push_start_cond(yyscanner, SCANSTATE_QUOTA); return QUOTA; }
 <SCANSTATE_QUOTA>{
-	"used"		{ return USED; }
 	"until"		{ return UNTIL; }
 }
 
+<SCANSTATE_QUOTA,SCANSTATE_LAST>"used"		{ return USED; }
+
 "hour"			{ return HOUR; }
 "day"			{ return DAY; }
 
diff --git a/src/statement.c b/src/statement.c
index eafc51c4..72455522 100644
--- a/src/statement.c
+++ b/src/statement.c
@@ -249,6 +249,36 @@ struct stmt *counter_stmt_alloc(const struct location *loc)
 	return stmt;
 }
 
+static void last_stmt_print(const struct stmt *stmt, struct output_ctx *octx)
+{
+	nft_print(octx, "last");
+
+	if (nft_output_stateless(octx))
+		return;
+
+	nft_print(octx, " used ");
+
+	if (stmt->last.set)
+		time_print(stmt->last.used, octx);
+	else
+		nft_print(octx, "never");
+}
+
+static const struct stmt_ops last_stmt_ops = {
+	.type		= STMT_LAST,
+	.name		= "last",
+	.print		= last_stmt_print,
+};
+
+struct stmt *last_stmt_alloc(const struct location *loc)
+{
+	struct stmt *stmt;
+
+	stmt = stmt_alloc(loc, &last_stmt_ops);
+	stmt->flags |= STMT_F_STATEFUL;
+	return stmt;
+}
+
 static const char *objref_type[NFT_OBJECT_MAX + 1] = {
 	[NFT_OBJECT_COUNTER]	= "counter",
 	[NFT_OBJECT_QUOTA]	= "quota",