lwip_etharp.c File Reference

ARP states.

Definition at line 80 of file lwip_etharp.c.

Search the ARP table for a matching or new entry.

If an IP address is given, return a pending or stable ARP entry that matches the address. If no match is found, create a new entry with this address set, but in state ETHARP_EMPTY. The caller must check and possibly change the state of the returned entry.

If ipaddr is NULL, return a initialized new entry in state ETHARP_EMPTY.

In all cases, attempt to create new entries from an empty entry. If no empty entries are available and ETHARP_FLAG_TRY_HARD flag is set, recycle old entries. Heuristic choose the least important entry for recycling.

Parameters:

ipaddr	IP address to find in ARP cache, or to add if not found.
flags	See etharp_state
netif	netif related to this address (used for NETIF_HWADDRHINT)

Returns:

The ARP entry index that matched or is created, ERR_MEM if no entry is found or could be recycled.

a) do a search through the cache, remember candidates b) select candidate entry c) create new entry

Definition at line 258 of file lwip_etharp.c.

Clean up ARP table entries.

Definition at line 170 of file lwip_etharp.c.

Clears expired entries in the ARP table.

This function should be called every ARP_TMR_INTERVAL milliseconds (1 second), in order to expire entries in the ARP table.

Definition at line 199 of file lwip_etharp.c.

Update (or insert) a IP/MAC address pair in the ARP cache.

If a pending entry is resolved, any queued packets will be sent at this point.

Parameters:

netif	netif related to this entry (used for NETIF_ADDRHINT)
ipaddr	IP address of the inserted ARP entry.
ethaddr	Ethernet address of the inserted ARP entry.
flags	See etharp_state

Returns:

• ERR_OK Successfully updated ARP cache.
• ERR_MEM If we could not add a new ARP entry when ETHARP_FLAG_TRY_HARD was set.
• ERR_ARG Non-unicast address given, those will not appear in ARP cache.

See also:

pbuf_free()

Add a new static entry to the ARP table. If an entry exists for the specified IP address, this entry is overwritten. If packets are queued for the specified IP address, they are sent out.

Parameters:

ipaddr	IP address for the new static entry
ethaddr	ethernet address for the new static entry

Returns:

See return values of etharp_add_static_entry

Remove a static entry from the ARP table previously added with a call to etharp_add_static_entry.

Parameters:

ipaddr

IP address of the static entry to remove

Returns:

ERR_OK: entry removed ERR_MEM: entry wasn't found ERR_ARG: entry wasn't a static entry but a dynamic one

Remove all ARP table entries of the specified netif.

Parameters:

netif

points to a network interface

Finds (stable) ethernet/IP address pair from ARP table using interface and IP address index.

Note:

the addresses in the ARP table are in network order!

Parameters:

netif	points to interface index
ipaddr	points to the (network order) IP address index
eth_ret	points to return pointer
ip_ret	points to return pointer

Returns:

table index if found, -1 otherwise

Possibility to iterate over stable ARP table entries

Parameters:

i	entry number, 0 to ARP_TABLE_SIZE
ipaddr	return value: IP address
netif	return value: points to interface
eth_ret	return value: ETH address

Returns:

1 on valid index, 0 otherwise

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:

p	The ARP packet that arrived on netif. Is freed by this function.
netif	The lwIP network interface on which the ARP packet pbuf arrived.

See also:

pbuf_free()

Just a small helper function that sends a pbuf to an ethernet address in the arp_table specified by the index 'arp_idx'.

Resolve and fill-in Ethernet address header for outgoing IP 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.
q	The pbuf(s) containing the IP packet to be sent.
ipaddr	The IP address of the packet destination.

Returns:

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

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.

Note:

q must only be ONE packet, not a packet queue!

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.

Send a raw ARP packet (opcode and all addresses can be modified)

Parameters:

netif	the lwip network interface on which to send the ARP packet
ethsrc_addr	the source MAC address for the ethernet header
ethdst_addr	the destination MAC address for the ethernet header
hwsrc_addr	the source MAC address for the ARP protocol header
ipsrc_addr	the source IP address for the ARP protocol header
hwdst_addr	the destination MAC address for the ARP protocol header
ipdst_addr	the destination IP address for the ARP protocol header
opcode	the type of the ARP packet

Returns:

ERR_OK if the ARP packet has been sent ERR_MEM if the ARP packet couldn't be allocated any other err_t on failure

Send an ARP request packet asking for ipaddr to a specific eth address. Used to send unicast request to refresh the ARP table just before an entry times out

Parameters:

netif	the lwip network interface on which to send the request
ipaddr	the IP address for which to ask
hw_dst_addr	the ethernet address to send this packet to

Returns:

ERR_OK if the request has been sent ERR_MEM if the ARP packet couldn't be allocated any other err_t on failure

Send an ARP request packet asking for ipaddr.

Parameters:

netif	the lwip network interface on which to send the request
ipaddr	the IP address for which to ask

Returns:

ERR_OK if the request has been sent ERR_MEM if the ARP packet couldn't be allocated any other err_t on failure

Definition at line 424 of file lwip_etharp.c.

Free a complete queue of etharp entries.

Parameters:

q	a qeueue of etharp_q_entry's to free

Definition at line 148 of file lwip_etharp.c.