Added UDP lite support for sockets

src/include/lwip/sockets.h

@@ -118,6 +118,7 @@ struct linger {
 #define IPPROTO_IP      0
 #define IPPROTO_TCP     6
 #define IPPROTO_UDP     17
+#define IPPROTO_UDPLITE 136
 
 #define INADDR_ANY      0
 #define INADDR_BROADCAST 0xffffffff
@@ -143,6 +144,15 @@ struct linger {
 #define TCP_KEEPCNT    0x05    /* set pcb->keep_cnt   - Use number of probes sent for get/setsockopt */
 #endif /* LWIP_TCP */
 
+#if LWIP_UDP && LWIP_UDPLITE
+/*
+ * Options for level IPPROTO_UDPLITE
+ */
+#define UDPLITE_SEND_CSCOV 0x01 /* sender checksum coverage */
+#define UDPLITE_RECV_CSCOV 0x02 /* minimal receiver checksum coverage */
+#endif
+
+
 #if LWIP_IGMP
 /*
  * Options and types for UDP multicast traffic handling

src/include/lwip/udp.h

@@ -70,7 +70,7 @@ struct udp_pcb {
   
 #if LWIP_UDPLITE
   /* used for UDP_LITE only */
-  u16_t chksum_len;
+  u16_t chksum_len_rx, chksum_len_tx;
 #endif /* LWIP_UDPLITE */
 
   /* addr and port are in same byte order as in the pcb */