88 lines
3.3 KiB
C
88 lines
3.3 KiB
C
/*
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LUFA Library
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Copyright (C) Dean Camera, 2019.
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dean [at] fourwalledcubicle [dot] com
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www.lufa-lib.org
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*/
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/*
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Copyright 2019 Dean Camera (dean [at] fourwalledcubicle [dot] com)
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Permission to use, copy, modify, distribute, and sell this
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software and its documentation for any purpose is hereby granted
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without fee, provided that the above copyright notice appear in
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all copies and that both that the copyright notice and this
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permission notice and warranty disclaimer appear in supporting
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documentation, and that the name of the author not be used in
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advertising or publicity pertaining to distribution of the
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software without specific, written prior permission.
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The author disclaims all warranties with regard to this
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software, including all implied warranties of merchantability
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and fitness. In no event shall the author be liable for any
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special, indirect or consequential damages or any damages
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whatsoever resulting from loss of use, data or profits, whether
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in an action of contract, negligence or other tortious action,
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arising out of or in connection with the use or performance of
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this software.
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*/
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/** \file
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*
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* Address Resolution Protocol (ARP) packet handling routines. This protocol handles the
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* conversion of physical MAC addresses to protocol IP addresses between the host and the
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* device.
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*/
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#include "ARP.h"
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/** Processes an ARP packet inside an Ethernet frame, and writes the appropriate response
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* to the output Ethernet frame if the host is requesting the IP or MAC address of the
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* virtual server device on the network.
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*
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* \param[in] InDataStart Pointer to the start of the incoming packet's ARP header
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* \param[out] OutDataStart Pointer to the start of the outgoing packet's ARP header
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*
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* \return The number of bytes written to the out Ethernet frame if any, NO_RESPONSE otherwise
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*/
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int16_t ARP_ProcessARPPacket(void* InDataStart,
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void* OutDataStart)
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{
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DecodeARPHeader(InDataStart);
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ARP_Header_t* ARPHeaderIN = (ARP_Header_t*)InDataStart;
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ARP_Header_t* ARPHeaderOUT = (ARP_Header_t*)OutDataStart;
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/* Ensure that the ARP request is a IPv4 request packet */
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if ((SwapEndian_16(ARPHeaderIN->ProtocolType) == ETHERTYPE_IPV4) &&
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(SwapEndian_16(ARPHeaderIN->Operation) == ARP_OPERATION_REQUEST))
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{
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/* If the ARP packet is requesting the MAC or IP of the virtual webserver, return the response */
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if (IP_COMPARE(&ARPHeaderIN->TPA, &ServerIPAddress) ||
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MAC_COMPARE(&ARPHeaderIN->THA, &ServerMACAddress))
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{
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/* Fill out the ARP response header */
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ARPHeaderOUT->HardwareType = ARPHeaderIN->HardwareType;
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ARPHeaderOUT->ProtocolType = ARPHeaderIN->ProtocolType;
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ARPHeaderOUT->HLEN = ARPHeaderIN->HLEN;
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ARPHeaderOUT->PLEN = ARPHeaderIN->PLEN;
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ARPHeaderOUT->Operation = SwapEndian_16(ARP_OPERATION_REPLY);
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/* Copy over the sender MAC/IP to the target fields for the response */
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ARPHeaderOUT->THA = ARPHeaderIN->SHA;
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ARPHeaderOUT->TPA = ARPHeaderIN->SPA;
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/* Copy over the new sender MAC/IP - MAC and IP addresses of the virtual webserver */
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ARPHeaderOUT->SHA = ServerMACAddress;
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ARPHeaderOUT->SPA = ServerIPAddress;
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/* Return the size of the response so far */
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return sizeof(ARP_Header_t);
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}
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}
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return NO_RESPONSE;
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}
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