[PATCH 05/15] NAN: Fix intersection logic in nan_ndl_determine_status()

[Andrei Otcheretianski]

Common schedule bitmap may be empty (but not NULL) if the peer has a
disjoint schedule on the same channel. Check properly that the common
schedule is either NULL or the intersection is empty.

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski at intel.com>
---
 src/nan/nan_ndl.c    |  2 +-
 src/utils/bitfield.c | 16 ++++++++++++++++
 src/utils/bitfield.h |  1 +
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/nan/nan_ndl.c b/src/nan/nan_ndl.c
index ce0e212cbe..1511f55931 100644
--- a/src/nan/nan_ndl.c
+++ b/src/nan/nan_ndl.c
@@ -513,7 +513,7 @@ static enum nan_ndl_status nan_ndl_determine_status(struct nan_data *nan,
 		own_chan_bf = NULL;
 	}
 
-	if (!common_bf) {
+	if (bitfield_is_empty(common_bf)) {
 		wpa_printf(MSG_DEBUG,
 			   "NAN: NDL: No common availability between local and peer");
 
diff --git a/src/utils/bitfield.c b/src/utils/bitfield.c
index b79f43516c..2cc6ec03f5 100644
--- a/src/utils/bitfield.c
+++ b/src/utils/bitfield.c
@@ -239,6 +239,22 @@ int bitfield_intersects(const struct bitfield *a, const struct bitfield *b)
 }
 
 
+int bitfield_is_empty(const struct bitfield *bf)
+{
+	size_t i, upper;
+
+	if (!bf)
+		return -1;
+
+	upper = (bf->max_bits + 7) / 8;
+	for (i = 0; i < upper; i++)
+		if (bf->bits[i])
+			return 0;
+
+	return 1;
+}
+
+
 void bitfield_dump(struct bitfield *bf, const char *title)
 {
 	wpa_printf(MSG_DEBUG, "bitfield: %s: max_bits=%zu",
diff --git a/src/utils/bitfield.h b/src/utils/bitfield.h
index db136cd176..d36e369926 100644
--- a/src/utils/bitfield.h
+++ b/src/utils/bitfield.h
@@ -26,6 +26,7 @@ int bitfield_intersect_in_place(struct bitfield *a, const struct bitfield *b);
 int bitfield_is_subset(const struct bitfield *a, const struct bitfield *b);
 size_t bitfield_size(const struct bitfield *bf);
 int bitfield_intersects(const struct bitfield *a, const struct bitfield *b);
+int bitfield_is_empty(const struct bitfield *bf);
 void bitfield_dump(struct bitfield *bf, const char *title);
 
 #endif /* BITFIELD_H */
-- 
2.53.0