fix(openwrt): detect radios and scan networks on vendor MediaTek drivers

Routers running MediaTek's proprietary mt_wifi SDK driver (e.g. GL.iNet)
never register with cfg80211/mac80211, so they have no `iw dev` entry and
no /sys/class/ieee80211 phy even though the radio is real and working —
find_wireless_iface was bailing with "No wireless radio found" on these.
Fall back to iwinfo's device listing, which abstracts over vendor backends
too, and to the vendor's iwpriv site-survey ioctl for scanning when iwinfo
itself can't trigger a scan on the interface.

core/openwrt/src/wifi_scan.rs

@@ -12,13 +12,57 @@ pub struct ScannedNetwork {
 pub fn scan_networks(router: &Router) -> Result<Vec<ScannedNetwork>> {
     let (iface, temp) = find_wireless_iface(router)?;
     let output = router.run_ok(&format!("iwinfo {} scan 2>&1", iface))?;
+    let result = if output.contains("Scanning not possible") {
+        // Vendor MediaTek `mt_wifi` driver (see find_wireless_iface) doesn't
+        // support scanning through iwinfo/nl80211 at all. Fall back to its own
+        // private ioctl site-survey, which works on the same interface.
+        scan_via_mtk_site_survey(router, &iface)
+    } else if output.contains("No scan results") || output.trim().is_empty() {
+        Ok(vec![])
+    } else {
+        parse_iwinfo_scan(&output)
+    };
     if temp {
         let _ = router.run(&format!("iw dev {} del 2>/dev/null", iface));
     }
-    if output.contains("No scan results") || output.trim().is_empty() {
-        return Ok(vec![]);
+    result
+}
+
+fn scan_via_mtk_site_survey(router: &Router, iface: &str) -> Result<Vec<ScannedNetwork>> {
+    let _ = router.run(&format!("iwpriv {} set SiteSurvey=1 2>/dev/null", iface));
+    std::thread::sleep(std::time::Duration::from_secs(4));
+    let output = router.run_ok(&format!("iwpriv {} get_site_survey 2>&1", iface))?;
+    parse_mtk_site_survey(&output)
+}
+
+/// Parses MediaTek's `iwpriv <iface> get_site_survey` fixed-width table.
+/// Column offsets come from the header row layout, which is part of the
+/// vendor SDK's ioctl response format shared across OEMs (GL.iNet, etc.),
+/// not something set per-device.
+fn parse_mtk_site_survey(output: &str) -> Result<Vec<ScannedNetwork>> {
+    let mut networks = Vec::new();
+    for line in output.lines() {
+        if !line.trim_start().as_bytes().first().is_some_and(u8::is_ascii_digit) {
+            continue; // skip header/summary lines; data rows start with an index
+        }
+        let ssid = line.get(8..41).unwrap_or("").trim().to_string();
+        if ssid.is_empty() {
+            continue;
+        }
+        let bssid = line.get(41..61).unwrap_or("").trim().to_string();
+        let security = line.get(61..84).unwrap_or("");
+        let channel: u8 = line.get(4..8).and_then(|s| s.trim().parse().ok()).unwrap_or(0);
+        let signal: i32 = line.get(84..92).and_then(|s| s.trim().parse().ok()).unwrap_or(-100);
+        networks.push(ScannedNetwork {
+            ssid,
+            bssid,
+            signal,
+            channel,
+            encryption: normalize_encryption(security),
+        });
     }
-    parse_iwinfo_scan(&output)
+    networks.sort_by(|a, b| b.signal.cmp(&a.signal));
+    Ok(networks)
 }
 
 /// Returns `(interface_name, is_temporary)`.
@@ -31,6 +75,17 @@ fn find_wireless_iface(router: &Router) -> Result<(String, bool)> {
         return Ok((out.trim().to_string(), false));
     }
 
+    // Some vendor wifi drivers (e.g. MediaTek's out-of-tree `mt_wifi`/`mtk` SDK
+    // driver used by GL.iNet and others) never register with cfg80211/mac80211,
+    // so they have no `iw dev` entry and no /sys/class/ieee80211 phy even though
+    // the radio is real and already up. `iwinfo` abstracts over those vendor
+    // backends too, so fall back to its device listing before concluding there's
+    // no radio at all.
+    let (iwinfo_out, _) = router.run("iwinfo 2>/dev/null | awk '/^[A-Za-z]/{print $1; exit}'")?;
+    if !iwinfo_out.trim().is_empty() {
+        return Ok((iwinfo_out.trim().to_string(), false));
+    }
+
     // Find the phy — if this is empty the device has no WiFi hardware at all
     let (phy_out, _) = router.run("ls /sys/class/ieee80211/ 2>/dev/null | head -1")?;
     let phy = phy_out.trim().to_string();