#79: add udp writer

lib/socketserver/GwUdpWriter.h

@@ -0,0 +1,28 @@
+#ifndef _GWUDPWRITER_H
+#define _GWUDPWRITER_H
+#include "GWConfig.h"
+#include "GwLog.h"
+#include "GwBuffer.h"
+#include "GwChannelInterface.h"
+#include <memory>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+
+class GwUdpWriter: public GwChannelInterface{
+    private:
+        const GwConfigHandler *config;
+        GwLog *logger;
+        int fd=-1;
+        int minId;
+        int port;
+        String address;
+        struct sockaddr_in destination;
+    public:
+        GwUdpWriter(const GwConfigHandler *config,GwLog *logger,int minId);
+        ~GwUdpWriter();
+        void begin();
+        virtual void loop(bool handleRead=true,bool handleWrite=true);
+        virtual size_t sendToClients(const char *buf,int sourceId, bool partialWrite=false);
+        virtual void readMessages(GwMessageFetcher *writer);
+};
+#endif