protocol/lufa/LUFA-git/Demos/Device/ClassDriver/RNDISEthernet/Lib/ICMP.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  *  Internet Control Message Protocol (ICMP) packet handling routines. This protocol handles
  34  *  Echo requests from the host, to indicate a successful network connection between the host
  35  *  and the virtual server.
  36  */
  37
  38 #include "ICMP.h"
  39
  40 /** Processes an ICMP packet inside an Ethernet frame, and writes the appropriate response
  41  *  to the output Ethernet frame if the host is issuing a ICMP ECHO request.
  42  *
  43  *  \param[in] FrameIN        Pointer to the incoming Ethernet frame information structure
  44  *  \param[in] InDataStart    Pointer to the start of the incoming packet's ICMP header
  45  *  \param[out] OutDataStart  Pointer to the start of the outgoing packet's ICMP header
  46  *
  47  *  \return The number of bytes written to the out Ethernet frame if any, NO_RESPONSE otherwise
  48  */
  49 int16_t ICMP_ProcessICMPPacket(Ethernet_Frame_Info_t* const FrameIN,
  50                                void* InDataStart,
  51                                void* OutDataStart)
  52 {
  53         ICMP_Header_t* ICMPHeaderIN  = (ICMP_Header_t*)InDataStart;
  54         ICMP_Header_t* ICMPHeaderOUT = (ICMP_Header_t*)OutDataStart;
  55
  56         DecodeICMPHeader(InDataStart);
  57
  58         /* Determine if the ICMP packet is an echo request (ping) */
  59         if (ICMPHeaderIN->Type == ICMP_TYPE_ECHOREQUEST)
  60         {
  61                 /* Fill out the ICMP response packet */
  62                 ICMPHeaderOUT->Type     = ICMP_TYPE_ECHOREPLY;
  63                 ICMPHeaderOUT->Code     = 0;
  64                 ICMPHeaderOUT->Checksum = 0;
  65                 ICMPHeaderOUT->Id       = ICMPHeaderIN->Id;
  66                 ICMPHeaderOUT->Sequence = ICMPHeaderIN->Sequence;
  67
  68                 intptr_t DataSize = FrameIN->FrameLength - ((((intptr_t)InDataStart + sizeof(ICMP_Header_t)) - (intptr_t)FrameIN->FrameData));
  69
  70                 /* Copy the remaining payload to the response - echo requests should echo back any sent data */
  71                 memmove(&((uint8_t*)OutDataStart)[sizeof(ICMP_Header_t)],
  72                         &((uint8_t*)InDataStart)[sizeof(ICMP_Header_t)],
  73                             DataSize);
  74
  75                 ICMPHeaderOUT->Checksum = Ethernet_Checksum16(ICMPHeaderOUT, (DataSize + sizeof(ICMP_Header_t)));
  76
  77                 /* Return the size of the response so far */
  78                 return (DataSize + sizeof(ICMP_Header_t));
  79         }
  80
  81         return NO_RESPONSE;
  82 }
  83