Win32: Re-init system proxy if internet settings change

Because Proxy Auto Configuration performs DNS lookups,
the proxy settings are being cached. For long-running
programs this means that once users switch e.g. from or
to company networks with a proxy, they instantly will
lose connectivity because we cache the old setting.

To remedy this, we monitor the Registry (locations
courtesy of Chromium's platform support) for changes
in its settings, and requery for the current proxy in
that case.

Task-number: QTBUG-3470
Task-number: QTBUG-29990
Change-Id: Id25a51387bcd232c5f879cea0371038986d0e2de
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>

1 files changed, 84 insertions, 2 deletions

diff --git a/src/network/kernel/qnetworkproxy_win.cpp b/src/network/kernel/qnetworkproxy_win.cpp
index da2c020a65..f7741ce86a 100644
--- a/src/network/kernel/qnetworkproxy_win.cpp
+++ b/src/network/kernel/qnetworkproxy_win.cpp
@@ -345,12 +345,66 @@ static QList<QNetworkProxy> parseServerList(const QNetworkProxyQuery &query, con
     return removeDuplicateProxies(result);
 }
 
+#if !defined(Q_OS_WINCE) && !defined(Q_OS_WINRT)
+namespace {
+class QRegistryWatcher {
+public:
+    void addLocation(HKEY hive, const QString& path)
+    {
+        HKEY openedKey;
+        if (RegOpenKeyEx(hive, reinterpret_cast<const wchar_t*>(path.utf16()), 0, KEY_READ, &openedKey) != ERROR_SUCCESS)
+            return;
+
+        const DWORD filter = REG_NOTIFY_CHANGE_NAME | REG_NOTIFY_CHANGE_ATTRIBUTES |
+                REG_NOTIFY_CHANGE_LAST_SET | REG_NOTIFY_CHANGE_SECURITY;
+
+        // Watch the registry key for a change of value.
+        HANDLE handle = CreateEvent(NULL, true, false, NULL);
+        if (RegNotifyChangeKeyValue(openedKey, true, filter, handle, true) != ERROR_SUCCESS) {
+            CloseHandle(handle);
+            return;
+        }
+        m_watchEvents.append(handle);
+        m_registryHandles.append(openedKey);
+    }
+
+    bool hasChanged() const {
+        return !isEmpty() &&
+               WaitForMultipleObjects(m_watchEvents.size(), m_watchEvents.data(), false, 0) < WAIT_OBJECT_0 + m_watchEvents.size();
+    }
+
+    bool isEmpty() const {
+        return m_watchEvents.isEmpty();
+    }
+
+    void clear() {
+        foreach (HANDLE event, m_watchEvents)
+            CloseHandle(event);
+        foreach (HKEY key, m_registryHandles)
+            RegCloseKey(key);
+
+        m_watchEvents.clear();
+        m_registryHandles.clear();
+    }
+
+    ~QRegistryWatcher() {
+        clear();
+    }
+
+private:
+    QVector<HANDLE> m_watchEvents;
+    QVector<HKEY> m_registryHandles;
+};
+} // namespace
+#endif // !defined(Q_OS_WINCE) && !defined(Q_OS_WINRT)
+
 class QWindowsSystemProxy
 {
 public:
     QWindowsSystemProxy();
     ~QWindowsSystemProxy();
     void init();
+    void reset();
 
     QMutex mutex;
 
@@ -361,7 +415,9 @@ public:
     QStringList proxyServerList;
     QStringList proxyBypass;
     QList<QNetworkProxy> defaultResult;
-
+#if !defined(Q_OS_WINCE) && !defined(Q_OS_WINRT)
+    QRegistryWatcher proxySettingsWatcher;
+#endif
     bool initialized;
     bool functional;
     bool isAutoConfig;
@@ -381,16 +437,42 @@ QWindowsSystemProxy::~QWindowsSystemProxy()
         ptrWinHttpCloseHandle(hHttpSession);
 }
 
+void QWindowsSystemProxy::reset()
+{
+    autoConfigUrl.clear();
+    proxyServerList.clear();
+    proxyBypass.clear();
+    defaultResult.clear();
+    defaultResult << QNetworkProxy::NoProxy;
+    functional = false;
+    isAutoConfig = false;
+}
+
 void QWindowsSystemProxy::init()
 {
-    if (initialized)
+    bool proxySettingsChanged = false;
+#if !defined(Q_OS_WINCE) && !defined(Q_OS_WINRT)
+    proxySettingsChanged = proxySettingsWatcher.hasChanged();
+#endif
+
+    if (initialized && !proxySettingsChanged)
         return;
     initialized = true;
 
+    reset();
+
 #ifdef Q_OS_WINCE
     // Windows CE does not have any of the following API
     return;
 #else
+
+#if !defined(Q_OS_WINCE) && !defined(Q_OS_WINRT)
+    proxySettingsWatcher.clear(); // needs reset to trigger a new detection
+    proxySettingsWatcher.addLocation(HKEY_CURRENT_USER,  QStringLiteral("Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings"));
+    proxySettingsWatcher.addLocation(HKEY_LOCAL_MACHINE, QStringLiteral("Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings"));
+    proxySettingsWatcher.addLocation(HKEY_LOCAL_MACHINE, QStringLiteral("Software\\Policies\\Microsoft\\Windows\\CurrentVersion\\Internet Settings"));
+#endif
+
     // load the winhttp.dll library
     QSystemLibrary lib(L"winhttp");
     if (!lib.load())