[nft PATCH 4/4] monitor: Ignore ranges' zero segment

[Phil Sutter <phil@nwl.cc>]

The internal representation of ranges in a set consists of segments
which either match or not. Each segment is identified by the lower
boundary and simply spans till the next segment. Upon insertion,
adjacent (matching) segments are joined into a single one, but only if
both are new. This means that the inverse operation, namely converting
segments back into ranges, may use the non-matching segments' lower
boundary as range end marker. But there is one catch: If the first range
doesn't start at zero, the first segment is a non-matching one. Code
indicates that by EXPR_F_INTERVAL_END flag. So when monitor sees a lower
boundary of zero with that flag set, it has to ignore it.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 src/netlink.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/netlink.c b/src/netlink.c
index 65c6f05a57649..8f9864129ea94 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -2214,6 +2214,7 @@ static int netlink_events_setelem_cb(const struct nlmsghdr *nlh, int type,
 	struct set *set;
 	const char *setname, *table;
 	uint32_t family;
+	struct expr *expr;
 
 	nls = netlink_setelem_alloc(nlh);
 	table = nftnl_set_get_str(nls, NFTNL_SET_TABLE);
@@ -2267,6 +2268,13 @@ static int netlink_events_setelem_cb(const struct nlmsghdr *nlh, int type,
 				free(setelem_cache.table);
 				free(setelem_cache.setname);
 			} else {
+				expr = compound_expr_last(dummyset->init);
+
+				if (!mpz_cmp_ui(expr->key->value, 0) &&
+				    expr->flags & EXPR_F_INTERVAL_END) {
+					set_free(dummyset);
+					goto out;
+				}
 				setelem_cache.type = type;
 				setelem_cache.family = family;
 				setelem_cache.table = xstrdup(table);
-- 
2.13.1