[RFC v2 66/99] wpa_supplicant: Implement nan_get_chans() callback

[Andrei Otcheretianski]

This callback is used to report own potential availability to NAN
module.
Iterate over all the operating classes and report all the channels that
are supported for NAN operation.
Increase preference for shared radio frequencies.
Don't report support for 40 MHz channels on 2.4GHz band and for
operating classes > 129 (i.e. 80+80, 6Ghz etc.).

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski at intel.com>
---
 wpa_supplicant/nan_supplicant.c | 126 +++++++++++++++++++++++++++++++-
 1 file changed, 123 insertions(+), 3 deletions(-)

diff --git a/wpa_supplicant/nan_supplicant.c b/wpa_supplicant/nan_supplicant.c
index c86b8d5fb1..b409da4f3d 100644
--- a/wpa_supplicant/nan_supplicant.c
+++ b/wpa_supplicant/nan_supplicant.c
@@ -218,14 +218,134 @@ static int wpas_nan_send_naf_cb(void *ctx, const u8 *dst, const u8 *src,
 }
 
 
-static int wpas_nan_get_chans_cb(void *ctx, u8 map_id, struct nan_channels *chans)
+static int nan_chan_info_cmp(const void *a, const void *b)
 {
+	const struct nan_channel_info *chan_a = a;
+	const struct nan_channel_info *chan_b = b;
+
+	return chan_b->pref - chan_a->pref;
+}
+
+
+static int wpas_nan_get_chans_cb(void *ctx, u8 map_id,
+				 struct nan_channels *chans)
+{
+	struct wpa_supplicant *wpa_s = ctx;
+	int *shared_freqs = NULL;
+	struct nan_channel_info *chan_list = NULL;
+	size_t chan_count = 0;
+	size_t chan_capacity = 0;
+	int op;
+
 	wpa_printf(MSG_DEBUG, "NAN: Get channels - map_id=%u", map_id);
 
-	/* TODO: Implement actual channel selection */
+	/* Allocate one extra element so it will be 0 terminated int_array */
+	shared_freqs = os_calloc(wpa_s->num_multichan_concurrent + 1,
+				 sizeof(int));
+	if (!shared_freqs) {
+		wpa_printf(MSG_DEBUG,
+			   "NAN: Failed to allocate memory for shared freqs");
+		goto fail;
+	}
+
+	if (get_shared_radio_freqs(wpa_s, shared_freqs,
+				   wpa_s->num_multichan_concurrent,
+				   false) < 0) {
+		wpa_printf(MSG_DEBUG, "NAN: Failed to get shared radio freqs");
+		goto fail;
+	}
+
+	/* Iterate through global operating classes */
+	for (op = 0; global_op_class[op].op_class; op++) {
+		const struct oper_class_map *o = &global_op_class[op];
+		int c;
+
+		 /* Don't support 80+, 6ghz etc yet */
+		if (o->op_class > 129)
+			continue;
+
+		/* Iterate through channels in this operating class */
+		for (c = o->min_chan; c <= o->max_chan; c += o->inc) {
+			int freq;
+			u8 center;
+			u8 pref;
+
+			/* Don't support 40 MHz channels on 2.4 GHz band */
+			if (o->mode == HOSTAPD_MODE_IEEE80211G &&
+			    o->bw != BW20)
+				continue;
+
+			if (!wpas_nan_valid_chan(wpa_s, o->mode, c, o->bw,
+						 o->op_class, &center))
+				continue;
+
+			freq = ieee80211_chan_to_freq(NULL, o->op_class, c);
+			if (freq < 0)
+				continue;
+
+			/* Determine preference based on shared frequencies */
+			if (int_array_includes(shared_freqs, freq)) {
+				pref = 3;
+			} else {
+				pref = 1;
+			}
+
+			/* Expand channel list if needed */
+			if (chan_count >= chan_capacity) {
+				size_t new_capacity = chan_capacity ?
+					chan_capacity * 2 : 16;
+				struct nan_channel_info *new_list;
+
+				new_list = os_realloc_array(
+					chan_list, new_capacity,
+					sizeof(struct nan_channel_info));
+				if (!new_list) {
+					wpa_printf(MSG_DEBUG,
+						   "NAN: Failed to expand channel list");
+					goto fail;
+				}
+				chan_list = new_list;
+				chan_capacity = new_capacity;
+			}
+
+			/* Add channel to list */
+			chan_list[chan_count].op_class = o->op_class;
+			chan_list[chan_count].channel = o->bw == BW80 ||
+							o->bw == BW160 ?
+							center : c;
+			chan_list[chan_count].pref = pref;
+
+			wpa_printf(MSG_DEBUG,
+				   "NAN: Added channel: op_class=%u, channel=%u, pref=%u",
+				   chan_list[chan_count].op_class,
+				   chan_list[chan_count].channel,
+				   chan_list[chan_count].pref);
+			chan_count++;
+		}
+	}
+
+	/* Sort channels by preference (higher preference first) */
+	if (chan_count > 1) {
+		qsort(chan_list, chan_count, sizeof(struct nan_channel_info),
+		      nan_chan_info_cmp);
+	}
+
+	chans->n_chans = chan_count;
+	chans->chans = chan_list;
+
+	os_free(shared_freqs);
+
+	wpa_printf(MSG_DEBUG,
+		   "NAN: Get channels completed - found %zu channels",
+		   chan_count);
+	return 0;
+
+fail:
+	os_free(shared_freqs);
+	os_free(chan_list);
 	chans->n_chans = 0;
 	chans->chans = NULL;
-	return 0;
+	return -1;
 }
 
 
-- 
2.49.0