ip6: add ip6-related definition

adapts to third-party code compilation. in the process of porting ConnMan,
we encounter some situations where the structure is not defined, or the
returned data types do not match the expectations. Refer to the common
implementation of other systems and add relevant definitions.

Signed-off-by: zhanghongyu <[email protected]>

Author: zhhyu7

include/netinet/ip6.h

@@ -32,6 +32,32 @@
  * Public Type Definitions
  ****************************************************************************/
 
+struct ip6_hdr
+{
+  union
+  {
+    struct ip6_hdrctl
+    {
+      uint32_t ip6_un1_flow;   /* 4 bits version, 8 bits TC, 20 bits flow-ID */
+      uint16_t ip6_un1_plen;   /* payload length */
+      uint8_t  ip6_un1_nxt;    /* next header */
+      uint8_t  ip6_un1_hlim;   /* hop limit */
+    } ip6_un1;
+
+    uint8_t ip6_un2_vfc;       /* 4 bits version, top 4 bits tclass */
+  } ip6_ctlun;
+
+  struct in6_addr ip6_src;      /* source address */
+  struct in6_addr ip6_dst;      /* destination address */
+};
+
+#define ip6_vfc   ip6_ctlun.ip6_un2_vfc
+#define ip6_flow  ip6_ctlun.ip6_un1.ip6_un1_flow
+#define ip6_plen  ip6_ctlun.ip6_un1.ip6_un1_plen
+#define ip6_nxt   ip6_ctlun.ip6_un1.ip6_un1_nxt
+#define ip6_hlim  ip6_ctlun.ip6_un1.ip6_un1_hlim
+#define ip6_hops  ip6_ctlun.ip6_un1.ip6_un1_hlim
+
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/