Fix crash in case system doesn't support IPv4 or IPv6

src/main.cpp

@@ -2018,6 +2018,7 @@ int main(int argc, char *argv[])
 
         // ServerConfig will use stk_config for server version testing
         stk_config->load(file_manager->getAsset("stk_config.xml"));
+        NetworkConfig::initSystemIP();
         // Client port depends on user config file and stk_config
         NetworkConfig::get()->initClientPort();
         bool no_graphics = !CommandLine::has("--graphical-server");

src/network/network_config.cpp

@@ -59,6 +59,48 @@
 #endif
 
 NetworkConfig *NetworkConfig::m_network_config[PT_COUNT];
+bool NetworkConfig::m_system_ipv4 = false;
+bool NetworkConfig::m_system_ipv6 = false;
+
+/** Initialize detection of system IPv4 or IPv6 support. */
+void NetworkConfig::initSystemIP()
+{
+    // It calls WSAStartup in enet, for the rest new Network function we don't
+    // need this because request manager runs curl_global_init which will do
+    // WSAStartup too
+    if (enet_initialize() != 0)
+    {
+        Log::error("NetworkConfig", "Could not initialize enet.");
+        return;
+    }
+    ENetAddress eaddr = {};
+    setIPv6Socket(0);
+    auto ipv4 = std::unique_ptr<Network>(new Network(1, 1, 0, 0, &eaddr));
+    setIPv6Socket(1);
+    auto ipv6 = std::unique_ptr<Network>(new Network(1, 1, 0, 0, &eaddr));
+    setIPv6Socket(0);
+    if (ipv4 && ipv4->getENetHost())
+        m_system_ipv4 = true;
+    if (ipv6 && ipv6->getENetHost())
+        m_system_ipv6 = true;
+    // If any 1 of them is missing set default network setting accordingly
+    if (!m_system_ipv4)
+    {
+        Log::warn("NetworkConfig", "System doesn't support IPv4");
+        if (m_system_ipv6)
+        {
+            UserConfigParams::m_ipv6_lan = true;
+            ServerConfig::m_ipv6_connection = true;
+        }
+    }
+    else if (!m_system_ipv6)
+    {
+        Log::warn("NetworkConfig", "System doesn't support IPv6");
+        UserConfigParams::m_ipv6_lan = false;
+        ServerConfig::m_ipv6_connection = false;
+    }
+    enet_deinitialize();
+}   // initSystemIP
 
 /** \class NetworkConfig
  *  This class is the interface between STK and the online code, particularly
@@ -224,6 +266,16 @@ void NetworkConfig::detectIPType()
         return;
     }
 #ifdef ENABLE_IPV6
+    if (!m_system_ipv4 || !m_system_ipv6)
+    {
+        // Don't test connection if only IPv4 or IPv6 system support
+        if (m_system_ipv4)
+            m_ip_type.store(IP_V4);
+        else if (m_system_ipv6)
+            m_ip_type.store(IP_V6);
+        return;
+    }
+
     ENetAddress eaddr = {};
     // We don't need to result of stun, just to check if the socket can be
     // used in ipv4 or ipv6
@@ -235,6 +287,10 @@ void NetworkConfig::detectIPType()
     auto ipv6 = std::unique_ptr<Network>(new Network(1, 1, 0, 0, &eaddr));
     setIPv6Socket(0);
 
+    // This should only happen if system doesn't support all socket types
+    if (!ipv4->getENetHost() || !ipv6->getENetHost())
+        return;
+
     auto& stunv4_map = UserConfigParams::m_stun_servers_v4;
     for (auto& s : getStunList(true/*ipv4*/))
     {

src/network/network_config.hpp

@@ -59,6 +59,10 @@ private:
     /** The singleton instance. */
     static NetworkConfig *m_network_config[PT_COUNT];
 
+    static bool m_system_ipv4;
+
+    static bool m_system_ipv6;
+
     enum NetworkType : int
     {
         NETWORK_NONE, NETWORK_WAN, NETWORK_LAN
@@ -125,6 +129,8 @@ private:
                              const std::string& dns);
 
 public:
+    static void initSystemIP();
+    // ------------------------------------------------------------------------
     /** Singleton get, which creates this object if necessary. */
     static NetworkConfig *get()
     {

src/network/servers_manager.cpp

@@ -164,6 +164,13 @@ std::shared_ptr<Online::XMLRequest> ServersManager::getLANRefreshRequest() const
             NetworkConfig::get()->setIPType(UserConfigParams::m_ipv6_lan ?
                 NetworkConfig::IP_DUAL_STACK : NetworkConfig::IP_V4);
             Network *broadcast = new Network(1, 1, 0, 0, &addr);
+            if (!broadcast->getENetHost())
+            {
+                setIPv6Socket(0);
+                m_success = true;
+                delete broadcast;
+                return;
+            }
             const std::vector<SocketAddress> &all_bcast =
                 ServersManager::get()->getBroadcastAddresses(
                 UserConfigParams::m_ipv6_lan);