NetworkManager: Decode SSID to UTF-8 (#10864)

wpa_supplicant returns all non-ASCII SSIDs as raw bytes in the form
\x0a. We interpret these bytes as UTF-8, and make sure that all invalid
characters are replaced with a �.

frontend/ui/network/manager.lua

@@ -943,7 +943,7 @@ function NetworkMgr:reconnectOrShowNetworkMenu(complete_callback, interactive)
             end
             UIManager:show(InfoMessage:new{
                 tag = "NetworkMgr", -- for crazy KOSync purposes
-                text = T(_("Connected to network %1"), BD.wrap(ssid)),
+                text = T(_("Connected to network %1"), BD.wrap(self.decodeSSID(ssid))),
                 timeout = 3,
             })
         else
@@ -995,6 +995,23 @@ function NetworkMgr:setWirelessBackend(name, options)
     require("ui/network/"..name).init(self, options)
 end
 
+function NetworkMgr.decodeSSID(text)
+    local decode = function(b)
+        local c = string.char(tonumber(b, 16))
+        -- This is a hack that allows us to make sure that any decoded backslash
+        -- does not get replaced in the step that replaces double backslashes.
+        if c == "\\" then
+            return "\\\\"
+        else
+            return c
+        end
+    end
+
+    local decoded = text:gsub("%f[\\]\\x(%x%x)", decode)
+    decoded = decoded:gsub("\\\\", "\\")
+    return util.fixUtf8(decoded, "<EFBFBD>")
+end
+
 -- set network proxy if global variable G_defaults:readSetting("NETWORK_PROXY") is defined
 if G_defaults:readSetting("NETWORK_PROXY") then
     NetworkMgr:setHTTPProxy(G_defaults:readSetting("NETWORK_PROXY"))