Added support for NSAPI_KEEPALIVE in LWIPInterface

LWIPInterface.cpp

@@ -545,6 +545,24 @@ int LWIPInterface::socket_recvfrom(void *handle, SocketAddress *addr, void *buf,
     return copied;
 }
 
+int LWIPInterface::setsockopt(void *handle, int level, int optname, const void *optval, unsigned optlen) {
+    struct lwip_socket *s = (struct lwip_socket *)handle;
+
+    switch (optname) {
+        case NSAPI_KEEPALIVE:
+            if (optlen != sizeof(int) || s->proto != NSAPI_TCP) {
+                return NSAPI_ERROR_UNSUPPORTED;
+            }
+
+            s->tcp->so_options |= SOF_KEEPALIVE;
+            s->tcp->keep_intvl = *(int*)optval;
+            return 0;
+            
+        default:
+            return NSAPI_ERROR_UNSUPPORTED;
+    }
+}
+
 void LWIPInterface::socket_attach(void *handle, void (*callback)(void *), void *data)
 {
     struct lwip_socket *s = (struct lwip_socket *)handle;

LWIPInterface.h

@@ -139,6 +139,21 @@ protected:
      */
     virtual int socket_recvfrom(void *handle, SocketAddress *address, void *buffer, unsigned size);
 
+    /*  Set stack-specific socket options
+     *
+     *  The setsockopt allow an application to pass stack-specific hints
+     *  to the underlying stack. For unsupported options,
+     *  NSAPI_ERROR_UNSUPPORTED is returned and the socket is unmodified.
+     *
+     *  @param handle   Socket handle
+     *  @param level    Stack-specific protocol level
+     *  @param optname  Stack-specific option identifier
+     *  @param optval   Option value
+     *  @param optlen   Length of the option value
+     *  @return         0 on success, negative error code on failure
+     */    
+    virtual int setsockopt(void *handle, int level, int optname, const void *optval, unsigned optlen);
+
     /** Register a callback on state change of the socket
      *  @param handle       Socket handle
      *  @param callback     Function to call on state change