Server can be started on a random free port

If the server is started with a port value of 0, it binds to a random
free port. The bound port can be obtained with a `getPort()` method.

include/server.h

@@ -53,6 +53,7 @@ namespace kiwix
        void setRoot(const std::string& root);
        void setAddress(const std::string& addr) { m_addr = addr; }
        void setPort(int port) { m_port = port; }
+       int getPort() const { return m_port; }
        void setNbThreads(int threads) { m_nbThreads = threads; }
        void setVerbose(bool verbose) { m_verbose = verbose; }
        void setTaskbar(bool withTaskbar, bool withLibraryButton)

src/server.cpp

@@ -109,6 +109,8 @@ class InternalServer {
     bool start();
     void stop();
 
+    int getPort() const { return m_port; }
+
   private:
     Response handle_request(const RequestContext& request);
     Response build_500(const std::string& msg);
@@ -162,7 +164,9 @@ bool Server::start() {
     m_withTaskbar,
     m_withLibraryButton,
     m_blockExternalLinks));
-  return mp_server->start();
+  auto s = mp_server->start();
+  m_port = mp_server->getPort();
+  return s;
 }
 
 void Server::stop() {
@@ -245,6 +249,8 @@ bool InternalServer::start() {
               << std::endl;
     return false;
   }
+  if (m_port == 0)
+    m_port = MHD_get_daemon_info(mp_daemon, MHD_DAEMON_INFO_BIND_PORT)->port;
   return true;
 }
 

test/server.cpp

@@ -50,6 +50,8 @@ ZimFileServer::ZimFileServer(int serverPort, std::string zimpath)
 
   if ( !server->start() )
     throw std::runtime_error("ZimFileServer failed to start");
+  if ( serverPort == 0 )
+    serverPort = server->getPort();
 
   client.reset(new httplib::Client(address, serverPort));
 }
@@ -64,7 +66,7 @@ class ServerTest : public ::testing::Test
 protected:
   std::unique_ptr<ZimFileServer>   zfs1_;
 
-  const int PORT = 8001;
+  const int PORT = 0;
   const std::string ZIMFILE = "./test/zimfile.zim";
 
 protected: