etharp.h File Reference

#include "lwip/pbuf.h"
#include "lwip/ip_addr.h"
#include "lwip/netif.h"
#include "lwip/ip.h"

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Classes
struct	eth_addr
struct	eth_hdr
struct	etharp_hdr
struct	ethip_hdr

Macros
#define	ETH_PAD_SIZE   0
#define	ARP_TMR_INTERVAL   5000
#define	ETHTYPE_ARP   0x0806
#define	ETHTYPE_IP   0x0800

Functions
void	etharp_init (void)
void	etharp_tmr (void)
void	etharp_ip_input (struct netif *netif, struct pbuf *p)
void	etharp_arp_input (struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
err_t	etharp_output (struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
err_t	etharp_query (struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
err_t	etharp_request (struct netif *netif, struct ip_addr *ipaddr)

Variables
PACK_STRUCT_BEGIN struct eth_addr	PACK_STRUCT_STRUCT

Macro Definition Documentation

ARP_TMR_INTERVAL

#define ARP_TMR_INTERVAL   5000

5 seconds period

ETH_PAD_SIZE

#define ETH_PAD_SIZE   0

ETHTYPE_ARP

#define ETHTYPE_ARP   0x0806

ETHTYPE_IP

#define ETHTYPE_IP   0x0800

Function Documentation

etharp_arp_input()

void etharp_arp_input	(	struct netif *	netif,
		struct eth_addr *	ethaddr,
		struct pbuf *	p
	)

Responds to ARP requests to us. Upon ARP replies to us, add entry to cache send out queued IP packets. Updates cache with snooped address pairs.

Should be called for incoming ARP packets. The pbuf in the argument is freed by this function.

Parameters

netif	The lwIP network interface on which the ARP packet pbuf arrived.
pbuf	The ARP packet that arrived on netif. Is freed by this function.
ethaddr	Ethernet address of netif.

Returns

NULL

See also

pbuf_free()

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etharp_init()

void etharp_init

(

void

)

Initializes ARP module.

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etharp_ip_input()

void etharp_ip_input	(	struct netif *	netif,
		struct pbuf *	p
	)

Updates the ARP table using the given IP packet.

Uses the incoming IP packet's source address to update the ARP cache for the local network. The function does not alter or free the packet. This function must be called before the packet p is passed to the IP layer.

Parameters

netif	The lwIP network interface on which the IP packet pbuf arrived.
pbuf	The IP packet that arrived on netif.

Returns

NULL

See also

pbuf_free()

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etharp_output()

err_t etharp_output	(	struct netif *	netif,
		struct ip_addr *	ipaddr,
		struct pbuf *	q
	)

Resolve and fill-in Ethernet address header for outgoing packet.

For IP multicast and broadcast, corresponding Ethernet addresses are selected and the packet is transmitted on the link.

For unicast addresses, the packet is submitted to etharp_query(). In case the IP address is outside the local network, the IP address of the gateway is used.

Parameters

netif	The lwIP network interface which the IP packet will be sent on.
ipaddr	The IP address of the packet destination.
pbuf	The pbuf(s) containing the IP packet to be sent.

Returns

• ERR_RTE No route to destination (no gateway to external networks), or the return type of either etharp_query() or netif->linkoutput().

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etharp_query()

err_t etharp_query	(	struct netif *	netif,
		struct ip_addr *	ipaddr,
		struct pbuf *	q
	)

Send an ARP request for the given IP address and/or queue a packet.

If the IP address was not yet in the cache, a pending ARP cache entry is added and an ARP request is sent for the given address. The packet is queued on this entry.

If the IP address was already pending in the cache, a new ARP request is sent for the given address. The packet is queued on this entry.

If the IP address was already stable in the cache, and a packet is given, it is directly sent and no ARP request is sent out.

If the IP address was already stable in the cache, and no packet is given, an ARP request is sent out.

Parameters

netif	The lwIP network interface on which ipaddr must be queried for.
ipaddr	The IP address to be resolved.
q	If non-NULL, a pbuf that must be delivered to the IP address. q is not freed by this function.

Returns

• ERR_BUF Could not make room for Ethernet header.
• ERR_MEM Hardware address unknown, and no more ARP entries available to query for address or queue the packet.
• ERR_MEM Could not queue packet due to memory shortage.
• ERR_RTE No route to destination (no gateway to external networks).
• ERR_ARG Non-unicast address given, those will not appear in ARP cache.

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etharp_request()

err_t etharp_request	(	struct netif *	netif,
		struct ip_addr *	ipaddr
	)

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etharp_tmr()

void etharp_tmr

(

void

)

Clears expired entries in the ARP table.

This function should be called every ETHARP_TMR_INTERVAL microseconds (5 seconds), in order to expire entries in the ARP table.

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Variable Documentation

PACK_STRUCT_STRUCT

PACK_STRUCT_END PACK_STRUCT_BEGIN struct ethip_hdr PACK_STRUCT_STRUCT