lwip corrected coverity and compiler warnings

Coverity ids: 1373147 and 1374442.

Author: Mika Leppänen

features/FEATURE_LWIP/lwip-interface/EthernetInterface.cpp

@@ -27,9 +27,14 @@ EthernetInterface::EthernetInterface()
 nsapi_error_t EthernetInterface::set_network(const char *ip_address, const char *netmask, const char *gateway)
 {
     _dhcp = false;
+
     strncpy(_ip_address, ip_address ? ip_address : "", sizeof(_ip_address));
+    _ip_address[sizeof(_ip_address) - 1] = '\0';
     strncpy(_netmask, netmask ? netmask : "", sizeof(_netmask));
+    _netmask[sizeof(_netmask) - 1] = '\0';
     strncpy(_gateway, gateway ? gateway : "", sizeof(_gateway));
+    _gateway[sizeof(_gateway) - 1] = '\0';
+
     return NSAPI_ERROR_OK;
 }
 

features/FEATURE_LWIP/lwip-interface/lwip_stack.c

@@ -109,7 +109,9 @@ static void mbed_lwip_socket_callback(struct netconn *nc, enum netconn_evt eh, u
 
 /* TCP/IP and Network Interface Initialisation */
 static struct netif lwip_netif;
+#if LWIP_IPV4
 static bool lwip_dhcp = false;
+#endif
 static char lwip_mac_address[NSAPI_MAC_SIZE];
 
 #if !LWIP_IPV4 || !LWIP_IPV6
@@ -190,7 +192,9 @@ static bool convert_lwip_addr_to_mbed(nsapi_addr_t *out, const ip_addr_t *in)
         return true;
     }
 #endif
+#if LWIP_IPV6 && LWIP_IPV4
     return false;
+#endif
 }
 
 static const ip_addr_t *mbed_lwip_get_ipv4_addr(const struct netif *netif)
@@ -325,13 +329,13 @@ static void mbed_lwip_netif_status_irq(struct netif *lwip_netif)
 static void mbed_lwip_set_mac_address(void)
 {
 #if (MBED_MAC_ADDRESS_SUM != MBED_MAC_ADDR_INTERFACE)
-    snprintf(lwip_mac_address, NSAPI_MAC_SIZE, "%02x:%02x:%02x:%02x:%02x:%02x",
+    (void) snprintf(lwip_mac_address, NSAPI_MAC_SIZE, "%02x:%02x:%02x:%02x:%02x:%02x",
             MBED_MAC_ADDR_0, MBED_MAC_ADDR_1, MBED_MAC_ADDR_2,
             MBED_MAC_ADDR_3, MBED_MAC_ADDR_4, MBED_MAC_ADDR_5);
 #else
     char mac[6];
     mbed_mac_address(mac);
-    snprintf(lwip_mac_address, NSAPI_MAC_SIZE, "%02x:%02x:%02x:%02x:%02x:%02x",
+    (void) snprintf(lwip_mac_address, NSAPI_MAC_SIZE, "%02x:%02x:%02x:%02x:%02x:%02x",
             mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
 #endif
 
@@ -366,7 +370,9 @@ char *mbed_lwip_get_ip_address(char *buf, nsapi_size_t buflen)
         return ip4addr_ntoa_r(ip_2_ip4(addr), buf, buflen);
     }
 #endif
+#if LWIP_IPV6 && LWIP_IPV4
     return NULL;
+#endif
 }
 
 const char *mbed_lwip_get_netmask(char *buf, nsapi_size_t buflen)
@@ -676,7 +682,7 @@ static nsapi_error_t mbed_lwip_socket_open(nsapi_stack_t *stack, nsapi_socket_t
         return NSAPI_ERROR_NO_SOCKET;
     }
 
-    u8_t lwip_proto = proto == NSAPI_TCP ? NETCONN_TCP : NETCONN_UDP;
+    enum netconn_type lwip_proto = proto == NSAPI_TCP ? NETCONN_TCP : NETCONN_UDP;
 
 #if LWIP_IPV6 && LWIP_IPV4
     const ip_addr_t *ip_addr;