From 00f02b19ad8ce2f8f0195d3610e06566bf68cd0c Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Fri, 10 Feb 2023 19:34:47 +0100
Subject: Added connection limit

---
 config.cpp             | 12 +++++++++++-
 config.h               |  3 +++
 debian/changelog       |  6 ++++++
 debian/whiteboard.conf |  8 ++++++++
 whiteboard.conf        |  8 ++++++++
 whiteboard.cpp         |  7 ++++++-
 6 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/config.cpp b/config.cpp
index d59156f..afb5cd2 100644
--- a/config.cpp
+++ b/config.cpp
@@ -14,6 +14,7 @@ namespace {
  const uint64_t default_maxage{0}; // timeout in seconds; 0 = no timeout
  const std::string default_listen {"::1:9000"};
  const int default_threads{1};
+ const int default_max_connections{1000};
 }
 
 Config::Config(const std::string& config_filename):
@@ -21,7 +22,8 @@ Config::Config(const std::string& config_filename):
  m_maxage{default_maxage},
  m_listenAddress{"::1"},
  m_listenPort{9000},
- m_threads{default_threads}
+ m_threads{default_threads},
+ m_max_connections{default_max_connections}
 {
 
  try {
@@ -42,6 +44,8 @@ Config::Config(const std::string& config_filename):
    throw std::runtime_error("Bad listen port: "s + std::to_string(m_listenPort));
 
   m_threads = tree.get<int>("config.threads", default_threads);
+  
+  m_max_connections = tree.get<int>("config.maxconnections", default_max_connections);
  } catch (const std::exception& ex) {
   std::cerr << "Error reading config file " << config_filename << ". Using defaults." << std::endl;
  }
@@ -71,3 +75,9 @@ int Config::getThreads() const
 {
  return m_threads;
 }
+
+int Config::getMaxConnections() const
+{
+ return m_max_connections;
+}
+
diff --git a/config.h b/config.h
index 01310aa..ce2fceb 100644
--- a/config.h
+++ b/config.h
@@ -12,6 +12,7 @@ private:
  std::string m_listenAddress; // ip address v4/v6
  int m_listenPort;
  int m_threads;
+ int m_max_connections;
 
 public:
  Config(const std::string& config_filename = default_config_filename);
@@ -22,4 +23,6 @@ public:
  int getListenPort() const;
 
  int getThreads() const;
+
+ int getMaxConnections() const;
 };
diff --git a/debian/changelog b/debian/changelog
index d773faf..c0cb704 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+whiteboard (1.8) UNRELEASED; urgency=medium
+
+  * Added config.maxconnections, defaults to 1000
+
+ -- Roland Reichwein <mail@reichwein.it>  Fri, 10 Feb 2023 19:18:16 +0100
+
 whiteboard (1.7) unstable; urgency=medium
 
   * Fix crash on stats.html page reload/close
diff --git a/debian/whiteboard.conf b/debian/whiteboard.conf
index 126bef5..6446d39 100644
--- a/debian/whiteboard.conf
+++ b/debian/whiteboard.conf
@@ -23,4 +23,12 @@
   Example: 4
  -->
  <threads>4</threads>
+ 
+ <!--
+  Maximum number of total concurrent websocket connections. Above this limit,
+  new connections will be rejected until old ones are closed.
+  Example: 500
+  Default: 1000
+ -->
+ <maxconnections>500</maxconnections>
 </config>
diff --git a/whiteboard.conf b/whiteboard.conf
index 055e7ba..4622db9 100644
--- a/whiteboard.conf
+++ b/whiteboard.conf
@@ -23,4 +23,12 @@
   Example: 4
  -->
  <threads>4</threads>
+ 
+ <!--
+  Maximum number of total concurrent websocket connections. Above this limit,
+  new connections will be rejected until old ones are closed.
+  Example: 500
+  Default: 1000
+ -->
+ <maxconnections>500</maxconnections>
 </config>
diff --git a/whiteboard.cpp b/whiteboard.cpp
index 6a71d3b..044321b 100644
--- a/whiteboard.cpp
+++ b/whiteboard.cpp
@@ -437,7 +437,12 @@ void Whiteboard::on_accept(boost::system::error_code ec, boost::asio::ip::tcp::s
  if (ec) {
   std::cerr << "Error on accept: " << ec.message() << std::endl;
  } else {
-  std::make_shared<session>(m_registry, *m_storage, m_storage_mutex, std::move(socket))->run();
+  if (m_registry.number_of_connections() >= m_config->getMaxConnections()) {
+   // limit reached
+   socket.close();
+  } else {
+   std::make_shared<session>(m_registry, *m_storage, m_storage_mutex, std::move(socket))->run();
+  }
  }
 
  do_accept();
-- 
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