v4转v6

ip转换：

const uint8_t g_zero_addr[128] = {0};
typedef struct 
{
    union
    {
        uint8_t     head[12];
        uint32_t u32_head[3];
    }head_un;
} mapped_head_t;
mapped_head_t g_v4_mapped_head;

int map_v4_to_v6(const struct in_addr *src_addr,struct in6_addr *dest_addr)
{
    unsigned char *p_dest_ip = NULL;
    g_v4_mapped_head.head_un.u32_head[2] = htonl(0x0000ffff);

    if(0 != memcmp(src_addr, g_zero_addr, sizeof(struct in_addr)))
    {
        p_dest_ip = (unsigned char *)dest_addr;
        memcpy(p_dest_ip + 12,src_addr, sizeof(struct in_addr));
        memcpy(p_dest_ip, g_v4_mapped_head.head_un.head, 12);
    }
    else
    {
        memset((char *)dest_addr, 0, sizeof(struct in6_addr));
        return -1;
    }
    return 0;

}