relibc/include/bits/netinet/in.h

#ifndef _BITS_NETINET_IN_H
#define _BITS_NETINET_IN_H

extern const struct in6_addr in6addr_any;
extern const struct in6_addr in6addr_loopback;
#define IN6ADDR_ANY_INIT { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } } }
#define IN6ADDR_LOOPBACK_INIT { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 } } }

// from musl {
#define IN6_IS_ADDR_UNSPECIFIED(a) \
        (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && \
         ((uint32_t *) (a))[2] == 0 && ((uint32_t *) (a))[3] == 0)

#define IN6_IS_ADDR_LOOPBACK(a) \
        (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && \
         ((uint32_t *) (a))[2] == 0 && \
         ((uint8_t *) (a))[12] == 0 && ((uint8_t *) (a))[13] == 0 && \
         ((uint8_t *) (a))[14] == 0 && ((uint8_t *) (a))[15] == 1 )

#define IN6_IS_ADDR_MULTICAST(a) (((uint8_t *) (a))[0] == 0xff)

#define IN6_IS_ADDR_LINKLOCAL(a) \
        ((((uint8_t *) (a))[0]) == 0xfe && (((uint8_t *) (a))[1] & 0xc0) == 0x80)

#define IN6_IS_ADDR_SITELOCAL(a) \
        ((((uint8_t *) (a))[0]) == 0xfe && (((uint8_t *) (a))[1] & 0xc0) == 0xc0)

#define IN6_IS_ADDR_V4MAPPED(a) \
        (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && \
         ((uint8_t *) (a))[8] == 0 && ((uint8_t *) (a))[9] == 0 && \
         ((uint8_t *) (a))[10] == 0xff && ((uint8_t *) (a))[11] == 0xff)

#define IN6_IS_ADDR_V4COMPAT(a) \
        (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && \
         ((uint32_t *) (a))[2] == 0 && ((uint8_t *) (a))[15] > 1)

#define IN6_IS_ADDR_MC_NODELOCAL(a) \
        (IN6_IS_ADDR_MULTICAST(a) && ((((uint8_t *) (a))[1] & 0xf) == 0x1))

#define IN6_IS_ADDR_MC_LINKLOCAL(a) \
        (IN6_IS_ADDR_MULTICAST(a) && ((((uint8_t *) (a))[1] & 0xf) == 0x2))

#define IN6_IS_ADDR_MC_SITELOCAL(a) \
        (IN6_IS_ADDR_MULTICAST(a) && ((((uint8_t *) (a))[1] & 0xf) == 0x5))

#define IN6_IS_ADDR_MC_ORGLOCAL(a) \
        (IN6_IS_ADDR_MULTICAST(a) && ((((uint8_t *) (a))[1] & 0xf) == 0x8))

#define IN6_IS_ADDR_MC_GLOBAL(a) \
        (IN6_IS_ADDR_MULTICAST(a) && ((((uint8_t *) (a))[1] & 0xf) == 0xe))

#define __ARE_4_EQUAL(a,b) \
	(!( (0[a]-0[b]) | (1[a]-1[b]) | (2[a]-2[b]) | (3[a]-3[b]) ))
#define IN6_ARE_ADDR_EQUAL(a,b) \
	__ARE_4_EQUAL((const uint32_t *)(a), (const uint32_t *)(b))

#define	IN_CLASSA(a)		((((in_addr_t)(a)) & 0x80000000) == 0)
#define	IN_CLASSA_NET		0xff000000
#define	IN_CLASSA_NSHIFT	24
#define	IN_CLASSA_HOST		(0xffffffff & ~IN_CLASSA_NET)
#define	IN_CLASSA_MAX		128
#define	IN_CLASSB(a)		((((in_addr_t)(a)) & 0xc0000000) == 0x80000000)
#define	IN_CLASSB_NET		0xffff0000
#define	IN_CLASSB_NSHIFT	16
#define	IN_CLASSB_HOST		(0xffffffff & ~IN_CLASSB_NET)
#define	IN_CLASSB_MAX		65536
#define	IN_CLASSC(a)		((((in_addr_t)(a)) & 0xe0000000) == 0xc0000000)
#define	IN_CLASSC_NET		0xffffff00
#define	IN_CLASSC_NSHIFT	8
#define	IN_CLASSC_HOST		(0xffffffff & ~IN_CLASSC_NET)
#define	IN_CLASSD(a)		((((in_addr_t)(a)) & 0xf0000000) == 0xe0000000)
#define	IN_MULTICAST(a)		IN_CLASSD(a)
#define	IN_EXPERIMENTAL(a)	((((in_addr_t)(a)) & 0xe0000000) == 0xe0000000)
#define	IN_BADCLASS(a) ((((in_addr_t)(a)) & 0xf0000000) == 0xf0000000)
// } from musl

#endif // _BITS_NETINET_IN_H