Corrected a bug in udp client :

Some data that the callback receive were not interpreted correctly (and it may not be okay still)

src/udp/udp_client.c

@@ -17,9 +17,9 @@ static inline void handle_receive(struct pbuf *p, const ip_addr_t *addr, u16_t p
     pbuf_free(p);
 }
 
-static inline void udp_receive_callback(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port)
+static void udp_receive_callback(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port)
 {
-    udp_client = *(udp_client_t *)&arg;
+    udp_client_t *udp_client_received_data = (udp_client_t *)arg;
     handle_receive(p, addr, port);
 }
 

src/udp/udp_server.c

@@ -83,5 +83,5 @@ void udp_server_send(const uint8_t *data, size_t length, const char *ip, uint16_
         }
     }
 
-    printf("Error sending data after %d tries...\n", retry);
+    printf("Error sending data after %d tries...\n", tries);
 }