tmk_core/protocol/lufa/LUFA-git/Demos/Device/ClassDriver/RNDISEthernet/Lib/Ethernet.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2014.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2014  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaims all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  Ethernet frame packet handling routines. This protocol handles the processing of raw Ethernet
  34  *  frames sent and received, deferring the processing of sub-packet protocols to the appropriate
  35  *  protocol handlers, such as DHCP or ARP.
  36  */
  37
  38 #include "Ethernet.h"
  39
  40 /** Constant for convenience when checking against or setting a MAC address to the virtual server MAC address. */
  41 const MAC_Address_t ServerMACAddress    = {SERVER_MAC_ADDRESS};
  42
  43 /** Constant for convenience when checking against or setting an IP address to the virtual server IP address. */
  44 const IP_Address_t  ServerIPAddress     = {SERVER_IP_ADDRESS};
  45
  46 /** Constant for convenience when checking against or setting a MAC address to the broadcast MAC address. */
  47 const MAC_Address_t BroadcastMACAddress = {BROADCAST_MAC_ADDRESS};
  48
  49 /** Constant for convenience when checking against or setting a IP address to the broadcast IP address. */
  50 const IP_Address_t  BroadcastIPAddress  = {BROADCAST_IP_ADDRESS};
  51
  52 /** Constant for convenience when checking against or setting an IP address to the client (host) IP address. */
  53 const IP_Address_t  ClientIPAddress     = {CLIENT_IP_ADDRESS};
  54
  55
  56 /** Processes an incoming Ethernet frame, and writes the appropriate response to the output Ethernet
  57  *  frame buffer if the sub protocol handlers create a valid response.
  58  */
  59 void Ethernet_ProcessPacket(Ethernet_Frame_Info_t* const FrameIN,
  60                             Ethernet_Frame_Info_t* const FrameOUT)
  61 {
  62         DecodeEthernetFrameHeader(FrameIN->FrameData);
  63
  64         /* Cast the incoming Ethernet frame to the Ethernet header type */
  65         Ethernet_Frame_Header_t* FrameINHeader  = (Ethernet_Frame_Header_t*)&FrameIN->FrameData;
  66         Ethernet_Frame_Header_t* FrameOUTHeader = (Ethernet_Frame_Header_t*)&FrameOUT->FrameData;
  67
  68         int16_t                  RetSize        = NO_RESPONSE;
  69
  70         /* Ensure frame is addressed to either all (broadcast) or the virtual webserver, and is a type II frame */
  71         if ((MAC_COMPARE(&FrameINHeader->Destination, &ServerMACAddress) ||
  72              MAC_COMPARE(&FrameINHeader->Destination, &BroadcastMACAddress)) &&
  73                  (SwapEndian_16(FrameIN->FrameLength) > ETHERNET_VER2_MINSIZE))
  74         {
  75                 /* Process the packet depending on its protocol */
  76                 switch (SwapEndian_16(FrameINHeader->EtherType))
  77                 {
  78                         case ETHERTYPE_ARP:
  79                                 RetSize = ARP_ProcessARPPacket(&FrameIN->FrameData[sizeof(Ethernet_Frame_Header_t)],
  80                                                                &FrameOUT->FrameData[sizeof(Ethernet_Frame_Header_t)]);
  81                                 break;
  82                         case ETHERTYPE_IPV4:
  83                                 RetSize = IP_ProcessIPPacket(FrameIN,
  84                                                              &FrameIN->FrameData[sizeof(Ethernet_Frame_Header_t)],
  85                                                              &FrameOUT->FrameData[sizeof(Ethernet_Frame_Header_t)]);
  86                                 break;
  87                 }
  88
  89                 /* Protocol processing routine has filled a response, complete the ethernet frame header */
  90                 if (RetSize > 0)
  91                 {
  92                         /* Fill out the response Ethernet frame header */
  93                         FrameOUTHeader->Source          = ServerMACAddress;
  94                         FrameOUTHeader->Destination     = FrameINHeader->Source;
  95                         FrameOUTHeader->EtherType       = FrameINHeader->EtherType;
  96
  97                         /* Set the response length in the buffer and indicate that a response is ready to be sent */
  98                         FrameOUT->FrameLength           = (sizeof(Ethernet_Frame_Header_t) + RetSize);
  99                 }
 100         }
 101
 102         /* Check if the packet was processed */
 103         if (RetSize != NO_PROCESS)
 104         {
 105                 /* Clear the frame buffer */
 106                 FrameIN->FrameLength = 0;
 107         }
 108 }
 109
 110 /** Calculates the appropriate ethernet checksum, consisting of the addition of the one's
 111  *  compliment of each word, complimented.
 112  *
 113  *  \param[in] Data   Pointer to the packet buffer data whose checksum must be calculated
 114  *  \param[in] Bytes  Number of bytes in the data buffer to process
 115  *
 116  *  \return A 16-bit Ethernet checksum value
 117  */
 118 uint16_t Ethernet_Checksum16(void* Data,
 119                              uint16_t Bytes)
 120 {
 121         uint16_t* Words    = (uint16_t*)Data;
 122         uint32_t  Checksum = 0;
 123
 124         for (uint16_t CurrWord = 0; CurrWord < (Bytes >> 1); CurrWord++)
 125           Checksum += Words[CurrWord];
 126
 127         while (Checksum & 0xFFFF0000)
 128           Checksum = ((Checksum & 0xFFFF) + (Checksum >> 16));
 129
 130         return ~Checksum;
 131 }
 132