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"))

frontend/ui/widget/networksetting.lua

@@ -106,6 +106,7 @@ local NetworkItem = InputContainer:extend{
     icon_size = Screen:scaleBySize(32),
     width = nil,
     info = nil,
+    decoded_ssid = nil,
     background = Blitbuffer.COLOR_WHITE,
 }
 
@@ -114,6 +115,7 @@ function NetworkItem:init()
     if not self.info.ssid then
         self.info.ssid = "[hidden]"
     end
+    self.decoded_ssid = NetworkMgr.decodeSSID(self.info.ssid)
 
     local wifi_icon
     if string.find(self.info.flags, "WPA") then
@@ -149,7 +151,7 @@ function NetworkItem:init()
                 },
                 horizontal_space,
                 TextWidget:new{
-                    text = self.info.ssid,
+                    text = self.decoded_ssid,
                     face = Font:getFace("cfont"),
                 },
             },
@@ -283,7 +285,7 @@ end
 function NetworkItem:onEditNetwork()
     local password_input
     password_input = InputDialog:new{
-        title = self.info.ssid,
+        title = self.decoded_ssid,
         input = self.info.password,
         input_hint = _("password (leave empty for open networks)"),
         input_type = "text",
@@ -326,7 +328,7 @@ end
 function NetworkItem:onAddNetwork()
     local password_input
     password_input = InputDialog:new{
-        title = self.info.ssid,
+        title = self.decoded_ssid,
         input = "",
         input_hint = _("password (leave empty for open networks)"),
         input_type = "text",
@@ -488,7 +490,7 @@ function NetworkSetting:init()
                 UIManager:close(self, "ui", self.dimen)
             end
             UIManager:show(InfoMessage:new{
-                text = T(_("Connected to network %1"), BD.wrap(connected_item.info.ssid)),
+                text = T(_("Connected to network %1"), BD.wrap(connected_item.decoded_ssid)),
                 timeout = 3,
             })
             if self.connect_callback then

spec/unit/network_manager_spec.lua

@@ -73,6 +73,30 @@ describe("network_manager module", function()
         assert.is.same(release_ip_called, 0)
     end)
 
+    describe("decodeSSID()", function()
+        local NetworkMgr = require("ui/network/manager")
+
+        it("should correctly unescape emoji", function()
+            assert.is_equal("📚", NetworkMgr.decodeSSID("\\xf0\\x9f\\x93\\x9a"))
+        end)
+
+        it("should correctly unescape multiple characters", function()
+            assert.is_equal("神舟五号", NetworkMgr.decodeSSID("\\xe7\\xa5\\x9e\\xe8\\x88\\x9f\\xe4\\xba\\x94\\xe5\\x8f\\xb7"))
+        end)
+
+        it("should ignore escaped backslashes", function()
+            assert.is_equal("\\x61", NetworkMgr.decodeSSID("\\\\x61"))
+        end)
+
+        it("should not remove encoded backslashes", function()
+            assert.is_equal("\\\\", NetworkMgr.decodeSSID("\\x5c\\"))
+        end)
+
+        it("should deal with invalid UTF-8 (relatively) gracefully", function()
+            assert.is_equal("<EFBFBD><EFBFBD>", NetworkMgr.decodeSSID("\\xe2\\x82"))
+        end)
+    end)
+
     teardown(function()
         function Device:initNetworkManager() end
         function Device:hasWifiRestore() return false end