Neighbor Cache

Neighbor cache component of neighbor information base. More...

Detailed Description

Neighbor cache component of neighbor information base.

Files
file	nc.h
	Neighbor cache definitions.

Data Structures
struct	gnrc_ipv6_nib_nc_t
	Neighbor cache entry view on NIB. More...

Functions
static unsigned	gnrc_ipv6_nib_nc_get_nud_state (const gnrc_ipv6_nib_nc_t *entry)
	Gets neighbor unreachability state from entry. More...
static bool	gnrc_ipv6_nib_nc_is_router (const gnrc_ipv6_nib_nc_t *entry)
	Gets router flag of a neighbor. More...
static unsigned	gnrc_ipv6_nib_nc_get_iface (const gnrc_ipv6_nib_nc_t *entry)
	Gets interface from entry. More...
static unsigned	gnrc_ipv6_nib_nc_get_ar_state (const gnrc_ipv6_nib_nc_t *entry)
	Gets address registration state of an entry. More...
int	gnrc_ipv6_nib_nc_set (const ipv6_addr_t *ipv6, unsigned iface, const uint8_t *l2addr, size_t l2addr_len)
	Adds an unmanaged neighbor entry to NIB. More...
void	gnrc_ipv6_nib_nc_del (const ipv6_addr_t *ipv6, unsigned iface)
	Deletes neighbor with address ipv6 from NIB. More...
void	gnrc_ipv6_nib_nc_mark_reachable (const ipv6_addr_t *ipv6)
	Mark neighbor with address ipv6 as reachable. More...
bool	gnrc_ipv6_nib_nc_iter (unsigned iface, void **state, gnrc_ipv6_nib_nc_t *nce)
	Iterates over all neighbor cache entries in the NIB. More...
void	gnrc_ipv6_nib_nc_print (gnrc_ipv6_nib_nc_t *nce)
	Prints a neighbor cache entry. More...

Info values
Values for gnrc_ipv6_nib_nc_t::info
#define	GNRC_IPV6_NIB_NC_INFO_NUD_STATE_MASK   (0x0007)
	Mask for neighbor unreachability detection (NUD) states. More...
#define	GNRC_IPV6_NIB_NC_INFO_NUD_STATE_UNMANAGED   (0x0000)
	Not managed by NUD.
#define	GNRC_IPV6_NIB_NC_INFO_NUD_STATE_UNREACHABLE   (0x0001)
	Entry is not reachable.
#define	GNRC_IPV6_NIB_NC_INFO_NUD_STATE_INCOMPLETE   (0x0002)
	Address resolution is currently performed.
#define	GNRC_IPV6_NIB_NC_INFO_NUD_STATE_STALE   (0x0003)
	Address might not be reachable.
#define	GNRC_IPV6_NIB_NC_INFO_NUD_STATE_DELAY   (0x0004)
	NUD will be performed in a moment.
#define	GNRC_IPV6_NIB_NC_INFO_NUD_STATE_PROBE   (0x0005)
	NUD is performed.
#define	GNRC_IPV6_NIB_NC_INFO_NUD_STATE_REACHABLE   (0x0006)
	Entry is reachable.
#define	GNRC_IPV6_NIB_NC_INFO_IS_ROUTER   (0x0008)
	gnrc_ipv6_nib_t::next_hop is router More...
#define	GNRC_IPV6_NIB_NC_INFO_IFACE_MASK   (0x01f0)
	Mask for interface identifier.
#define	GNRC_IPV6_NIB_NC_INFO_IFACE_POS   (4)
	Shift position of interface identifier.
#define	GNRC_IPV6_NIB_NC_INFO_AR_STATE_MASK   (0x0600)
	Mask for 6LoWPAN address registration (6Lo-AR) states. More...
#define	GNRC_IPV6_NIB_NC_INFO_AR_STATE_POS   (9)
	Shift position of address registration states.
#define	GNRC_IPV6_NIB_NC_INFO_AR_STATE_GC   (0x0000)
	Not managed by 6Lo-AR (address can be removed when memory is low.
#define	GNRC_IPV6_NIB_NC_INFO_AR_STATE_TENTATIVE   (0x0200)
	Address registration still pending at upstream router.
#define	GNRC_IPV6_NIB_NC_INFO_AR_STATE_REGISTERED   (0x0400)
	Address is registered.
#define	GNRC_IPV6_NIB_NC_INFO_AR_STATE_MANUAL   (0x0600)
	Address was added manually.

Macro Definition Documentation

GNRC_IPV6_NIB_NC_INFO_AR_STATE_MASK

#define GNRC_IPV6_NIB_NC_INFO_AR_STATE_MASK   (0x0600)

Mask for 6LoWPAN address registration (6Lo-AR) states.

See also

RFC 6775, section 3.5

Definition at line 111 of file nc.h.

GNRC_IPV6_NIB_NC_INFO_IS_ROUTER

#define GNRC_IPV6_NIB_NC_INFO_IS_ROUTER   (0x0008)

gnrc_ipv6_nib_t::next_hop is router

This flag indicates that gnrc_ipv6_nib_t::next_hop is a router, but it does not necessarily indicate that it is in the default router list! A neighbor that has this flag unset however must not appear in the default router list.

See also

RFC 4861, Appendix D

Definition at line 94 of file nc.h.

GNRC_IPV6_NIB_NC_INFO_NUD_STATE_MASK

#define GNRC_IPV6_NIB_NC_INFO_NUD_STATE_MASK   (0x0007)

Mask for neighbor unreachability detection (NUD) states.

See also

RFC 4861, section 7.3.2

RFC 7048

Definition at line 47 of file nc.h.

Function Documentation

gnrc_ipv6_nib_nc_del()

void gnrc_ipv6_nib_nc_del	(	const ipv6_addr_t *	ipv6,
		unsigned	iface
	)

Deletes neighbor with address ipv6 from NIB.

Precondition

ipv6 != NULL

Parameters

[in]	ipv6	The neighbor's IPv6 address.
[in]	iface	The interface to the neighbor.

If the ipv6 can't be found for a neighbor in the NIB nothing happens.

gnrc_ipv6_nib_nc_get_ar_state()

static unsigned gnrc_ipv6_nib_nc_get_ar_state ( const gnrc_ipv6_nib_nc_t *  entry )

inlinestatic

Gets address registration state of an entry.

Parameters

[in]

entry

A neighbor cache entry

Returns

The address registration state of entry.

Definition at line 202 of file nc.h.

gnrc_ipv6_nib_nc_get_iface()

static unsigned gnrc_ipv6_nib_nc_get_iface ( const gnrc_ipv6_nib_nc_t *  entry )

inlinestatic

Gets interface from entry.

Parameters

[in]

entry

A neighbor cache entry

Returns

The interface identifier of entry.

0 if no interface is identified for entry.

Definition at line 189 of file nc.h.

gnrc_ipv6_nib_nc_get_nud_state()

static unsigned gnrc_ipv6_nib_nc_get_nud_state ( const gnrc_ipv6_nib_nc_t *  entry )

inlinestatic

Gets neighbor unreachability state from entry.

Parameters

[in]

entry

A neighbor cache entry.

Returns

The neighbor unreachability state of entry.

Definition at line 163 of file nc.h.

gnrc_ipv6_nib_nc_is_router()

static bool gnrc_ipv6_nib_nc_is_router ( const gnrc_ipv6_nib_nc_t *  entry )

inlinestatic

Gets router flag of a neighbor.

Parameters

[in]

entry

A neighbor cache entry.

Returns

true, if entry is a router.

false, if entry is not a router.

Definition at line 176 of file nc.h.

gnrc_ipv6_nib_nc_iter()

bool gnrc_ipv6_nib_nc_iter	(	unsigned	iface,
		void **	state,
		gnrc_ipv6_nib_nc_t *	nce
	)

Iterates over all neighbor cache entries in the NIB.

Precondition

(state != NULL) && (nce != NULL)

Parameters

[in]	iface	Restrict iteration to entries on this interface. 0 for any interface.
[in,out]	state	Iteration state of the neighbor cache. Must point to a NULL pointer to start iteration.
[out]	nce	The next neighbor cache entry.

Usage example:

#include "net/gnrc/ipv6/nib/nc.h"
 
int main(void) {
    void *state = NULL;
    gnrc_ipv6_nib_nc_t nce;
 
    puts("My neighbors:");
    while (gnrc_ipv6_nib_nc_iter(0, &state, &nce)) {
        gnrc_ipv6_nib_nc_print(&nce);
    }
    return 0;
}

Note

The list may change during iteration.

Returns

true, if iteration can be continued.

false, if nce is the last neighbor cache entry in the NIB.

gnrc_ipv6_nib_nc_mark_reachable()

void gnrc_ipv6_nib_nc_mark_reachable

(

const ipv6_addr_t *

ipv6

)

Mark neighbor with address ipv6 as reachable.

Precondition

ipv6 != NULL

Parameters

[in]

ipv6

A neighbor's IPv6 address. Must not be NULL.

This function shall be called if an upper layer gets reachability confirmation via its own means (e.g. a TCP connection build-up or confirmation). Unmanaged neighbor cache entries (i.e. entries created using gnrc_ipv6_nib_nc_set()) or entries whose next-hop are not yet in the neighbor cache are ignored.

Entries in state GNRC_IPV6_NIB_NC_INFO_NUD_STATE_UNMANAGED are not affected by this, since they are assumed to always be reachable and kept out of the NUD state-machine

gnrc_ipv6_nib_nc_print()

void gnrc_ipv6_nib_nc_print

(

gnrc_ipv6_nib_nc_t *

nce

)

Prints a neighbor cache entry.

Precondition

nce != NULL

Parameters

[in]

nce

A neighbor cache entry.

gnrc_ipv6_nib_nc_set()

int gnrc_ipv6_nib_nc_set	(	const ipv6_addr_t *	ipv6,
		unsigned	iface,
		const uint8_t *	l2addr,
		size_t	l2addr_len
	)

Adds an unmanaged neighbor entry to NIB.

Precondition

ipv6 != NULL

l2addr_len <= CONFIG_GNRC_IPV6_NIB_L2ADDR_MAX_LEN

(iface > KERNEL_PID_UNDEF) && (iface <= KERNEL_PID_LAST)

Parameters

[in]	ipv6	The neighbor's IPv6 address.
[in]	iface	The interface to the neighbor.
[in]	l2addr	The neighbor's L2 address.
[in]	l2addr_len	Length of l2addr.

A neighbor cache entry created this way is marked as persistent. Also, a non-persistent neighbor or destination cache entry already in the NIB might be removed to make room for the new entry. If an entry pointing to the same IPv6 address as ipv6 exists already it will be overwritten and marked as unmanaged.

If CONFIG_GNRC_IPV6_NIB_ARSM == 0 l2addr and l2addr_len won't be set and ipv6 must be a link-local address.

Returns

0 on success.

-ENOMEM, if no space is left in neighbor cache.

-EINVAL, if ipv6 is invalid (i.e. CONFIG_GNRC_IPV6_NIB_ARSM == 0 and ipv6 is not link-local).