1 files changed, 70 insertions, 0 deletions
diff --git a/dnsdist-concurrent-connections.hh b/dnsdist-concurrent-connections.hh
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+++ b/dnsdist-concurrent-connections.hh
@@ -0,0 +1,70 @@
+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#pragma once
+
+#include <map>
+#include "iputils.hh"
+#include "lock.hh"
+
+namespace dnsdist
+{
+class IncomingConcurrentTCPConnectionsManager
+{
+public:
+  static bool accountNewTCPConnection(const ComboAddress& from)
+  {
+    if (s_maxTCPConnectionsPerClient == 0) {
+      return true;
+    }
+    auto db = s_tcpClientsConcurrentConnectionsCount.lock();
+    auto& count = (*db)[from];
+    if (count >= s_maxTCPConnectionsPerClient) {
+      return false;
+    }
+    ++count;
+    return true;
+  }
+
+  static void accountClosedTCPConnection(const ComboAddress& from)
+  {
+    if (s_maxTCPConnectionsPerClient == 0) {
+      return;
+    }
+    auto db = s_tcpClientsConcurrentConnectionsCount.lock();
+    auto& count = db->at(from);
+    count--;
+    if (count == 0) {
+      db->erase(from);
+    }
+  }
+
+  static void setMaxTCPConnectionsPerClient(size_t max)
+  {
+    s_maxTCPConnectionsPerClient = max;
+  }
+
+private:
+  static LockGuarded<std::map<ComboAddress, size_t, ComboAddress::addressOnlyLessThan>> s_tcpClientsConcurrentConnectionsCount;
+  static size_t s_maxTCPConnectionsPerClient;
+};
+
+}