luci-mod-network: improve wifi scan status reporting

Attempt to properly report the scan status by treating 404 replies as
not yet completed scans and empty array replies as successful scans
that did not yield any results.

Fixes: #2874
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

2 files changed, 15 insertions, 7 deletions

diff --git a/modules/luci-mod-network/htdocs/luci-static/resources/view/network/wifi_join.js b/modules/luci-mod-network/htdocs/luci-static/resources/view/network/wifi_join.js
index d5bd7b0a6..af926ab4a 100644
--- a/modules/luci-mod-network/htdocs/luci-static/resources/view/network/wifi_join.js
+++ b/modules/luci-mod-network/htdocs/luci-static/resources/view/network/wifi_join.js
@@ -113,6 +113,7 @@ function scan() {
 		var count = 0;
 
 		poll = L.poll(3, L.url('admin/network/wireless_scan_results', dev), null, function(s, results) {
+
 			if (Array.isArray(results)) {
 				var bss = [];
 
@@ -143,9 +144,13 @@ function scan() {
 					]);
 				});
 
-				cbi_update_table(tbl, bss, E('em', { class: 'spinning' }, _('No scan results available yet...')));
+				cbi_update_table(tbl, bss, E('em' {}, _('No networks in range')));
+			}
+			else {
+				cbi_update_table(tbl, [], E('em', { class: 'spinning' }, _('No scan results available yet...')));
 			}
 
+
 			if (count++ >= 3) {
 				count = 0;
 				L.post(L.url('admin/network/wireless_scan_trigger', dev, 1), null, function() {});
diff --git a/modules/luci-mod-network/luasrc/controller/admin/network.lua b/modules/luci-mod-network/luasrc/controller/admin/network.lua
index fac8d95a2..b20607e2e 100644
--- a/modules/luci-mod-network/luasrc/controller/admin/network.lua
+++ b/modules/luci-mod-network/luasrc/controller/admin/network.lua
@@ -311,7 +311,7 @@ local function _wifi_get_scan_results(cache_key)
 		return results.values[cache_key]
 	end
 
-	return { }
+	return nil
 end
 
 function wifi_scan_trigger(radio, update)
@@ -343,10 +343,13 @@ function wifi_scan_trigger(radio, update)
 		end
 
 		if update then
-			for _, bss in ipairs(_wifi_get_scan_results(cache_key)) do
-				if not bssids[bss.bssid] then
-					bss.stale = true
-					data[#data + 1] = bss
+			local cached = _wifi_get_scan_results(cache_key)
+			if cached then
+				for _, bss in ipairs(cached) do
+					if not bssids[bss.bssid] then
+						bss.stale = true
+						data[#data + 1] = bss
+					end
 				end
 			end
 		end
@@ -361,7 +364,7 @@ end
 function wifi_scan_results(radio)
 	local results = radio and _wifi_get_scan_results("scan_%s" % radio)
 
-	if results and #results > 0 then
+	if results then
 		luci.http.prepare_content("application/json")
 		luci.http.write_json(results)
 	else