different modes for UDP writer, allow to select network

lib/socketserver/GwUdpWriter.h

@@ -9,14 +9,59 @@
 #include <arpa/inet.h>
 
 class GwUdpWriter: public GwChannelInterface{
+    public:
+    using UType=enum{
+        T_BCALL=0,
+        T_BCAP=1,
+        T_BCSTA=2,
+        T_NORM=3,
+        T_MCALL=4,
+        T_MCAP=5,
+        T_MCSTA=6,
+        T_UNKNOWN=-1
+    };
     private:
+        class WriterSocket{
+            public:
+            int fd=-1;
+            struct in_addr srcA;
+            struct sockaddr_in dstA;
+            String source;
+            String destination;
+            int port;
+            GwLog *logger;
+            using SourceMode=enum {
+                S_UNBOUND=0,
+                S_MC,
+                S_SRC
+            };
+            SourceMode sourceMode;
+            WriterSocket(GwLog *logger,int p,const String &src,const String &dst, SourceMode sm);
+            void close(){
+                if (fd > 0){
+                    ::close(fd);
+                }
+                fd=-1;
+            }
+            ~WriterSocket(){
+                close();
+            }
+            bool changed(const String &newSrc, const String &newDst);
+            size_t send(const char *buf,size_t len);
+        };
         const GwConfigHandler *config;
         GwLog *logger;
-        int fd=-1;
+        /**
+         * we use fd/address to send to the AP network
+         * and fd2,address2 to send to the station network
+         * for type "normal" we only use fd
+        */
+        WriterSocket *apSocket=nullptr; //also for T_NORM
+        WriterSocket *staSocket=nullptr;
         int minId;
         int port;
-        String address;
-        struct sockaddr_in destination;
+        UType type=T_UNKNOWN;
+        void checkStaSocket();
     public:
         GwUdpWriter(const GwConfigHandler *config,GwLog *logger,int minId);
         ~GwUdpWriter();