Multiple listeners at same port now triggers an error

Author: jvde-github

Source/IO/Network.cpp

@@ -612,15 +612,16 @@ namespace IO
 
 				for (const auto &s : data[i].NMEA)
 				{
-					if (SendTo((s + "\r\n").c_str()) < 0) {
+					if (SendTo((s + "\r\n").c_str()) < 0)
+					{
 						first_message = true;
 						if (!persistent)
 						{
 							Error() << "TCP feed: requesting termination.";
 							StopRequest();
 						}
 					}
-					else 
+					else
 						first_message = false;
 				}
 			}
@@ -642,7 +643,7 @@ namespace IO
 						StopRequest();
 					}
 				}
-				else 
+				else
 					first_message = false;
 			}
 		}
@@ -778,7 +779,11 @@ namespace IO
 		ss << ", json: " << Util::Convert::toString(fmt) << ".";
 
 		Info() << ss.str();
-		Server::start(port);
+
+		if (!Server::start(port))
+		{
+			throw std::runtime_error("TCP listener: cannot start server at port " + std::to_string(port) + ".");
+		}
 	}
 
 	Setting &TCPlistenerStreamer::Set(std::string option, std::string arg)

Source/Library/TCP.cpp

@@ -61,6 +61,7 @@ namespace TCP
 {
 
 	const int TCP::Server::MAX_CONN;
+	std::vector<int> Server::active_ports;
 	// TO DO: create a BaseSocket class and clean up between files Network (AC streamers) and TCP (low level TCP connections)
 
 	void ServerConnection::Lock()
@@ -261,6 +262,19 @@ namespace TCP
 			run_thread.join();
 		if (sock != -1)
 			closesocket(sock);
+
+		// Remove port from active_ports
+		if (listening_port != -1)
+		{
+			for (auto it = active_ports.begin(); it != active_ports.end(); ++it)
+			{
+				if (*it == listening_port)
+				{
+					active_ports.erase(it);
+					break;
+				}
+			}
+		}
 	}
 
 	int Server::numberOfClients()
@@ -473,6 +487,15 @@ namespace TCP
 
 	bool Server::start(int port)
 	{
+		// Check if port is already in use
+		for (const auto& p : active_ports)
+		{
+			if (p == port)
+			{
+				Error() << "TCP Server: port " << port << " is already in use by another server instance";
+				return false;
+			}
+		}
 
 		sock = socket(AF_INET, SOCK_STREAM, 0);
 		if (sock < 0)
@@ -528,6 +551,9 @@ namespace TCP
 		else
 			Info() << "TCP Server: start thread at IP " << IP_BIND << " port " << port;
 
+		listening_port = port;
+		active_ports.push_back(port);
+
 		run_thread = std::thread(&Server::Run, this);
 
 		return true;

Source/Library/TCP.h

@@ -110,6 +110,9 @@ namespace TCP
 		int timeout = 30;
 		bool reuse_port = true;
 		std::string IP_BIND;
+		int listening_port = -1;
+
+		static std::vector<int> active_ports;
 
 		const static int MAX_CONN = 16;
 		std::array<ServerConnection, MAX_CONN> client;