fff-web: Use iw instead of iwinfo for wifiscan

This prepares the fff-web package for removal of the iwinfo binary.

Instead of using the 'iwinfo' wrapper, the nl80211 utility 'iw' is used
from now on, which is possible, because we only support devices with
nl80211 drivers anyway.

Because iw reports the frequency instead of the channel, and does not allow
easily parsing the mode and encryption parameters, the table is adjusted accordingly.

Signed-off-by: Fabian Bläse <fabian@blaese.de>
Reviewed-by: Robert Langhammer <rlanghammer@web.de>

src/packages/fff/fff-web/files/www/ssl/cgi-bin/wifiscan.html

@@ -8,18 +8,14 @@
 	<table class="wifitable">
 		<tr>
 			<th>Name</th>
-			<th>Kanal</th>
+			<th>Frequenz</th>
 			<th>Signal</th>
-			<th>Typ</th>
 			<th>MAC</th>
-			<th>Encryption</th>
 		</tr>
 
 <%
-iwinfo w2mesh scan |\
-	awk -v RS='' \
-	'{r = gensub(/.*Address: ([0-9A-F:]*)?.*ESSID: "?([^"\n]*)"?.*Mode: ([^ ]*).*Channel: ([0-9]*).*Signal: (-[0-9]*) dBm.*Encryption: ([^"]*).*/, \
-	"<!-- \\5 --><tr><td>\\2</td><td>\\4</td><td>\\5 dBm</td><td>\\3</td><td>\\1</td><td>\\6</td></tr>", "g"); print r;}' | sort -n | sed 's#&#\&amp;#'
+iw dev w2mesh scan | sed 's/^BSS/\nBSS/g' |\
+	awk -v RS='' '{r = gensub(/.*BSS ([0-9a-f:]*)?.*freq: ([0-9]*).*signal: (-[0-9]*\.[0-9]*) dBm.*SSID: ([^\n]*).*/, "<!-- \\3 --><tr><td>\\4</td><td>\\2 MHz</td><td>\\3 dBm</td><td>\\1</td></tr>", "g"); print r;}' | sort -n | sed 's#&#\&amp;#'
 	# The HTML comment contains the signal quality to allow sorting
 %>
 	</table>