chain plugin note
網路位元組序轉化爲本地位元組序，網路位元組序按照大端格式存放
uint32_t ntohl(uint32_t n)
{
union { int i; char c; } u = { 1 };
return u.c ? bswap_32(n) : n;
}
#define bswap_32(x) __bswap_32(x)
static __inline uint32_t __bswap_32(uint32_t __x)
{
return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
}