feat(core): Store default bootstrap list separate from user list

Allows qTox to tell the difference between a default list that should be
upgraded when defaults are changed, ora user list that should never be changed.

doc/user_manual_en.md

@@ -463,9 +463,10 @@ information.
 ## Bootstrap Nodes
 
 qTox uses bootstrap nodes to find its way in to the DHT. The list of nodes is
-stored in `bootstrapNodes.json` and can be found and modified if wanted at
-`~/.config/tox/` on Linux, `%APPDATA%\Roaming\tox` on Windows, and
-`~/Library/Application Support/Tox` on macOS.
+stored in `~/.config/tox/` on Linux, `%APPDATA%\Roaming\tox` on Windows, and
+`~/Library/Application Support/Tox` on macOS. `bootstrapNodes.example.json`
+stores the default list. If a new list is placed at `bootstrapNodes.json`, it
+will be used instead.
 
 ## Avoiding Censorship
 

src/net/bootstrapnodeupdater.cpp

@@ -201,6 +201,19 @@ QByteArray serialize(QList<DhtServer> nodes)
     QJsonDocument doc{rootObj};
     return doc.toJson(QJsonDocument::Indented);
 }
+
+void createExampleBootstrapNodesFile(const Paths& paths)
+{
+    // deserialize and reserialize instead of just copying to strip out any unnecessary json, making it easier for
+    // users to edit. Overwrite the file on every start to keep it up to date when our internal list updates.
+    auto buildInNodes = loadNodesFile(builtinNodesFile);
+    auto serializedNodes = serialize(buildInNodes);
+
+    QFile outFile(paths.getExampleNodesFilePath());
+    outFile.open(QIODevice::WriteOnly | QIODevice::Text);
+    outFile.write(serializedNodes.data(), serializedNodes.size());
+    outFile.close();
+}
 } // namespace
 
 /**
@@ -211,25 +224,18 @@ BootstrapNodeUpdater::BootstrapNodeUpdater(const QNetworkProxy& proxy, Paths& _p
     : proxy{proxy}
     , paths{_paths}
     , QObject{parent}
-{}
+{
+    createExampleBootstrapNodesFile(_paths);
+}
 
 QList<DhtServer> BootstrapNodeUpdater::getBootstrapnodes() const
 {
     auto userFilePath = paths.getUserNodesFilePath();
-    if (!QFile(userFilePath).exists()) {
-        qInfo() << "Bootstrap node list not found, creating one with default nodes.";
-        // deserialize and reserialize instead of just copying to strip out any unnecessary json, making it easier for
-        // users to edit
-        auto buildInNodes = loadNodesFile(builtinNodesFile);
-        auto serializedNodes = serialize(buildInNodes);
-
-        QFile outFile(userFilePath);
-        outFile.open(QIODevice::WriteOnly | QIODevice::Text);
-        outFile.write(serializedNodes.data(), serializedNodes.size());
-        outFile.close();
+    if (QFile::exists(userFilePath)) {
+        return loadNodesFile(userFilePath);
+    } else {
+        return loadNodesFile(builtinNodesFile);
     }
-
-    return loadNodesFile(userFilePath);
 }
 
 void BootstrapNodeUpdater::requestBootstrapNodes()

src/persistence/paths.cpp

@@ -365,6 +365,13 @@ QString Paths::getAppCacheDirPath() const
 #endif
 }
 
+QString Paths::getExampleNodesFilePath() const
+{
+    QDir dir(getSettingsDirPath());
+    constexpr static char nodesFileName[] = "bootstrapNodes.example.json";
+    return dir.filePath(nodesFileName);
+}
+
 QString Paths::getUserNodesFilePath() const
 {
     QDir dir(getSettingsDirPath());

src/persistence/paths.h

@@ -51,6 +51,7 @@ public:
     QString getSettingsDirPath() const;
     QString getAppDataDirPath() const;
     QString getAppCacheDirPath() const;
+    QString getExampleNodesFilePath() const;
     QString getUserNodesFilePath() const;
 #endif