Implement code to move old key files out of the way

llarp/config/key_manager.cpp

@@ -15,12 +15,33 @@ namespace llarp
   bool
   KeyManager::initializeFromDisk(bool genIfAbsent)
   {
-    // TODO:
-    // 1) start with the RouterContact file. We can detect the version from
-    //    this and decide whether or not the existing keys need updating.
-    // 2) Backup existing files if necessary
-    // 3) Write new files if necessary
-    // 4) Load files to be obtained later
+
+    RouterContact rc;
+    if (!rc.Read(m_rcPath.c_str()))
+    {
+        LogWarn("Could not read RouterContact at path ", m_rcPath);
+        return false;
+    }
+
+    if (rc.keyfileVersion < LLARP_KEYFILE_VERSION) {
+      if (! genIfAbsent) {
+        LogError("Our RouterContact", m_rcPath, "is out of date");
+      } else {
+        LogWarn("Our RouterContact", m_rcPath,
+            "is out of date, backing up and regenerating private keys");
+
+        if (! backupKeyFilesByMoving()) {
+          LogError("Could not mv some key files, please ensure key files"
+              " are backed up if needed and remove");
+          return false;
+        }
+
+        // TODO: generate files
+      }
+    }
+
+    // TODO: load files
+
     return true;
   }
 
@@ -48,4 +69,47 @@ namespace llarp
     return true;
   }
 
+  bool
+  KeyManager::backupKeyFilesByMoving() const
+  {
+    auto findFreeBackupFilename = [](const fs::path& filepath) {
+      for (int i=0; i<9; i++)
+      {
+        std::string ext("." + std::to_string(i) + ".bak");
+        fs::path newPath = filepath;
+        newPath += ext;
+
+        if (not fs::exists(newPath))
+          return newPath;
+      }
+      return fs::path();
+    };
+
+    std::vector<std::string> files = {
+      m_rcPath,
+      m_idKeyPath,
+      m_encKeyPath,
+      m_transportKeyPath
+    };
+
+    for (auto& filepath : files)
+    {
+      fs::path newFilepath = findFreeBackupFilename(filepath);
+      if (newFilepath.empty())
+      {
+        LogWarn("Could not find an appropriate backup filename for", filepath);
+        return false;
+      }
+
+      LogInfo("Backing up (moving) key file", filepath, "to", newFilepath, "...");
+
+      std::error_code ec;
+      fs::rename(filepath, newFilepath, ec);
+      if (ec) {
+        LogError("Failed to move key file", ec.message());
+        return false;
+      }
+    }
+  }
+
 }  // namespace llarp

llarp/config/key_manager.hpp

@@ -67,10 +67,13 @@ namespace llarp
   private:
 
     std::string m_rcPath;
-    std::string m_snKeyPath;
     std::string m_idKeyPath;
     std::string m_encKeyPath;
     std::string m_transportKeyPath;
+
+    /// Backup each key file (by copying, e.g. foo -> foo.bak)
+    bool
+    backupKeyFilesByMoving() const;
   };
 
 }  // namespace llarp