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126 lines
4.8 KiB
126 lines
4.8 KiB
/*! \file arp.h \brief ARP Protocol Library. */
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//*****************************************************************************
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//
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// File Name : 'arp.h'
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// Title : ARP Protocol Library
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// Author : Pascal Stang
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// Created : 9/7/2004
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// Revised : 7/3/2005
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// Version : 0.1
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// Target MCU : Atmel AVR series
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// Editor Tabs : 4
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//
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/// \ingroup network
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/// \defgroup arp ARP Protocol Library (arp.c)
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/// \code #include "net/arp.h" \endcode
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/// \par Description
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/// To send anything over ethernet (or most any other physical network)
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/// a packet must be addressed to a physical network node address, often
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/// called a MAC/hardware/ethernet address. This MAC address identifies
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/// a specific interface (like the ethernet card in your computer) on the
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/// network.
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/// ARP (Address Resolution Protocol) assists in mapping IP addresses to
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/// the MAC addresses required to actually get data to its destination.
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/// In other words, an IP address is not enough to send information over
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/// ethernet. You need the MAC address of the network interface/card that
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/// "owns" that IP address. ARP maintains a table mapping IP addresses to
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/// MAC addresses. This table can be filled by both listening to
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/// traffic on the network, as well as making specific ARP requests if
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/// an IP<->MAC mapping is not in the table.
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///
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/// \note This code is currently below version 1.0, and therefore is considered
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/// to be lacking in some functionality or documentation, or may not be fully
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/// tested. Nonetheless, you can expect most functions to work.
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///
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// This code is distributed under the GNU Public License
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// which can be found at http://www.gnu.org/licenses/gpl.txt
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//*****************************************************************************
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//@{
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#ifndef ARP_H
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#define ARP_H
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#include "net.h"
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#ifndef ARP_TABLE_SIZE
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#define ARP_TABLE_SIZE 4
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#endif
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#ifndef ARP_CACHE_TIME_TO_LIVE
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#define ARP_CACHE_TIME_TO_LIVE 100
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#endif
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// #define ARP_DEBUG
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// #define ARP_DEBUG_PRINT
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/*! Initialize ARP system.
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Clears ARP table and prepares it for use. This is typically done
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once at program initialization. */
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void arpInit(void);
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/*! Set IP and Ethernet hardware/MAC address.
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This must be done before valid replies can be generated for ARP
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requests. Typically done once at program initialization. */
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void arpSetAddress(struct netEthAddr* myeth, uint32_t myip);
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/*! Processes incoming ARP packets.
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This function is to be called when an ARP type packet has arrived
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over the network. If the packet type is an ARP request for us,
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an ARP reply will be generated and sent. */
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void arpArpIn(unsigned int len, struct netEthArpHeader* packet);
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/*! Process incoming IP packets to harvest IP<->MAC relationships.
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This function should be called when IP packets are received over the
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network. It does nothing more than harvest the IP<->MAC address
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relationships from the ethernet and IP header of the packet. The
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packet is not changed nor processed. Nothing is sent on the network.
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Use of this command is not required, but it is a good way to
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automatically fill the ARP table with information about nodes that are
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active on the network.
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\warning On very busy or heavily populated netorks, this can quickly
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fill the ARP table with unnecessary entries, and/or cause some CPU load.
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*/
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void arpIpIn(struct netEthIpHeader* packet);
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/*! Process outgoing IP packet to fill in ethernet header information.
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To be sent on a network, an IP packet must have the correct ethernet
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header information appended to the front. This function will fill
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in this information.
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A physical destination IP address argument is needed to support
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sending to a gateway (i.e. when a packet is destined for a node that
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is not on this network, IP addressing is as usual, but we phyiscally
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send the packet to the gateway's ethernet address/interface).
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\warning Technically, if an IP<->MAC address mapping is not in the
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ARP table, then the IP packet should be held while an ARP request is
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made, and the reply received. However, in single-threaded ram-limited
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embedded systems, such a holdup is unacceptable. This function instead
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sends the packet as an ethernet broadcast if a mapping cannot be found.
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\todo Send the packet broadcast AND send an ARP request, if a mapping
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is not found.
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*/
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void arpIpOut(struct netEthIpHeader* packet, uint32_t phyDstIp);
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/*! Periodic ARP cache maintenance.
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This function is to be called once per second and will slowly
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expire old ARP cache entries. */
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void arpTimer(void);
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/*! Check if this IP address is present in the ARP cache. Internal function.
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If IP address is found, function returns index of entry. If not found,
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returns -1. */
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int arpMatchIp(uint32_t ipaddr);
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//! Print diagnotic information about ARP packet.
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void arpPrintHeader(struct netArpHeader* packet);
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//! Print diagnotic information about ARP cache.
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void arpPrintTable(void);
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#endif
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//@}
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