137 lines
5.3 KiB
C
137 lines
5.3 KiB
C
/*
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LUFA Library
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Copyright (C) Dean Camera, 2017.
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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 2017 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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* Ethernet frame packet handling routines. This protocol handles the processing of raw Ethernet
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* frames sent and received, deferring the processing of sub-packet protocols to the appropriate
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* protocol handlers, such as DHCP or ARP.
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*/
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#include "Ethernet.h"
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/** Ethernet Frame buffer structure, to hold the incoming Ethernet frame from the host. */
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Ethernet_Frame_Info_t FrameIN;
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/** Ethernet Frame buffer structure, to hold the outgoing Ethernet frame to the host. */
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Ethernet_Frame_Info_t FrameOUT;
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/** Constant for convenience when checking against or setting a MAC address to the virtual server MAC address. */
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const MAC_Address_t ServerMACAddress = {SERVER_MAC_ADDRESS};
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/** Constant for convenience when checking against or setting an IP address to the virtual server IP address. */
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const IP_Address_t ServerIPAddress = {SERVER_IP_ADDRESS};
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/** Constant for convenience when checking against or setting a MAC address to the broadcast MAC address. */
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const MAC_Address_t BroadcastMACAddress = {BROADCAST_MAC_ADDRESS};
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/** Constant for convenience when checking against or setting a IP address to the broadcast IP address. */
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const IP_Address_t BroadcastIPAddress = {BROADCAST_IP_ADDRESS};
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/** Constant for convenience when checking against or setting an IP address to the client (host) IP address. */
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const IP_Address_t ClientIPAddress = {CLIENT_IP_ADDRESS};
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/** Processes an incoming Ethernet frame, and writes the appropriate response to the output Ethernet
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* frame buffer if the sub protocol handlers create a valid response.
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*/
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void Ethernet_ProcessPacket(void)
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{
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DecodeEthernetFrameHeader(FrameIN.FrameData);
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/* Cast the incoming Ethernet frame to the Ethernet header type */
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Ethernet_Frame_Header_t* FrameINHeader = (Ethernet_Frame_Header_t*)&FrameIN.FrameData;
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Ethernet_Frame_Header_t* FrameOUTHeader = (Ethernet_Frame_Header_t*)&FrameOUT.FrameData;
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int16_t RetSize = NO_RESPONSE;
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/* Ensure frame is addressed to either all (broadcast) or the virtual webserver, and is a type II frame */
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if ((MAC_COMPARE(&FrameINHeader->Destination, &ServerMACAddress) ||
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MAC_COMPARE(&FrameINHeader->Destination, &BroadcastMACAddress)) &&
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(SwapEndian_16(FrameIN.FrameLength) > ETHERNET_VER2_MINSIZE))
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{
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/* Process the packet depending on its protocol */
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switch (SwapEndian_16(FrameINHeader->EtherType))
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{
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case ETHERTYPE_ARP:
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RetSize = ARP_ProcessARPPacket(&FrameIN.FrameData[sizeof(Ethernet_Frame_Header_t)],
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&FrameOUT.FrameData[sizeof(Ethernet_Frame_Header_t)]);
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break;
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case ETHERTYPE_IPV4:
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RetSize = IP_ProcessIPPacket(&FrameIN.FrameData[sizeof(Ethernet_Frame_Header_t)],
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&FrameOUT.FrameData[sizeof(Ethernet_Frame_Header_t)]);
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break;
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}
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/* Protocol processing routine has filled a response, complete the ethernet frame header */
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if (RetSize > 0)
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{
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/* Fill out the response Ethernet frame header */
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FrameOUTHeader->Source = ServerMACAddress;
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FrameOUTHeader->Destination = FrameINHeader->Source;
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FrameOUTHeader->EtherType = FrameINHeader->EtherType;
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/* Set the response length in the buffer and indicate that a response is ready to be sent */
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FrameOUT.FrameLength = (sizeof(Ethernet_Frame_Header_t) + RetSize);
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}
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}
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/* Check if the packet was processed */
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if (RetSize != NO_PROCESS)
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{
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/* Clear the frame buffer */
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FrameIN.FrameLength = 0;
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}
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}
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/** Calculates the appropriate ethernet checksum, consisting of the addition of the one's
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* compliment of each word, complimented.
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*
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* \param[in] Data Pointer to the packet buffer data whose checksum must be calculated
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* \param[in] Bytes Number of bytes in the data buffer to process
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*
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* \return A 16-bit Ethernet checksum value
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*/
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uint16_t Ethernet_Checksum16(void* Data,
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uint16_t Bytes)
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{
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uint16_t* Words = (uint16_t*)Data;
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uint32_t Checksum = 0;
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for (uint16_t CurrWord = 0; CurrWord < (Bytes >> 1); CurrWord++)
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Checksum += Words[CurrWord];
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while (Checksum & 0xFFFF0000)
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Checksum = ((Checksum & 0xFFFF) + (Checksum >> 16));
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return ~Checksum;
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}
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