129 lines
5.5 KiB
C
129 lines
5.5 KiB
C
/*
|
|
LUFA Library
|
|
Copyright (C) Dean Camera, 2017.
|
|
|
|
dean [at] fourwalledcubicle [dot] com
|
|
www.lufa-lib.org
|
|
*/
|
|
|
|
/*
|
|
Copyright 2017 Dean Camera (dean [at] fourwalledcubicle [dot] com)
|
|
|
|
Permission to use, copy, modify, distribute, and sell this
|
|
software and its documentation for any purpose is hereby granted
|
|
without fee, provided that the above copyright notice appear in
|
|
all copies and that both that the copyright notice and this
|
|
permission notice and warranty disclaimer appear in supporting
|
|
documentation, and that the name of the author not be used in
|
|
advertising or publicity pertaining to distribution of the
|
|
software without specific, written prior permission.
|
|
|
|
The author disclaims all warranties with regard to this
|
|
software, including all implied warranties of merchantability
|
|
and fitness. In no event shall the author be liable for any
|
|
special, indirect or consequential damages or any damages
|
|
whatsoever resulting from loss of use, data or profits, whether
|
|
in an action of contract, negligence or other tortious action,
|
|
arising out of or in connection with the use or performance of
|
|
this software.
|
|
*/
|
|
|
|
/** \file
|
|
*
|
|
* Dynamic Host Configuration Protocol (DHCP) packet handling routines. This protocol
|
|
* handles the automatic IP negotiation to the host, so that the host will use the provided
|
|
* IP address given to it by the device.
|
|
*/
|
|
|
|
#include "DHCP.h"
|
|
|
|
/** Processes a DHCP packet inside an Ethernet frame, and writes the appropriate response
|
|
* to the output Ethernet frame if the host is requesting or accepting an IP address.
|
|
*
|
|
* \param[in] IPHeaderInStart Pointer to the start of the incoming packet's IP header
|
|
* \param[in] DHCPHeaderInStart Pointer to the start of the incoming packet's DHCP header
|
|
* \param[out] DHCPHeaderOutStart Pointer to the start of the outgoing packet's DHCP header
|
|
*
|
|
* \return The number of bytes written to the out Ethernet frame if any, NO_RESPONSE otherwise
|
|
*/
|
|
int16_t DHCP_ProcessDHCPPacket(void* IPHeaderInStart,
|
|
void* DHCPHeaderInStart,
|
|
void* DHCPHeaderOutStart)
|
|
{
|
|
IP_Header_t* IPHeaderIN = (IP_Header_t*)IPHeaderInStart;
|
|
DHCP_Header_t* DHCPHeaderIN = (DHCP_Header_t*)DHCPHeaderInStart;
|
|
DHCP_Header_t* DHCPHeaderOUT = (DHCP_Header_t*)DHCPHeaderOutStart;
|
|
|
|
uint8_t* DHCPOptionsINStart = ((uint8_t*)DHCPHeaderInStart + sizeof(DHCP_Header_t));
|
|
uint8_t* DHCPOptionsOUTStart = ((uint8_t*)DHCPHeaderOutStart + sizeof(DHCP_Header_t));
|
|
|
|
DecodeDHCPHeader(DHCPHeaderInStart);
|
|
|
|
/* Zero out the response DHCP packet, as much of it is legacy and left at 0 */
|
|
memset(DHCPHeaderOUT, 0, sizeof(DHCP_Header_t));
|
|
|
|
/* Fill out the response DHCP packet */
|
|
DHCPHeaderOUT->HardwareType = DHCPHeaderIN->HardwareType;
|
|
DHCPHeaderOUT->Operation = DHCP_OP_BOOTREPLY;
|
|
DHCPHeaderOUT->HardwareAddressLength = DHCPHeaderIN->HardwareAddressLength;
|
|
DHCPHeaderOUT->Hops = 0;
|
|
DHCPHeaderOUT->TransactionID = DHCPHeaderIN->TransactionID;
|
|
DHCPHeaderOUT->ElapsedSeconds = 0;
|
|
DHCPHeaderOUT->Flags = DHCPHeaderIN->Flags;
|
|
DHCPHeaderOUT->YourIP = ClientIPAddress;
|
|
memmove(&DHCPHeaderOUT->ClientHardwareAddress, &DHCPHeaderIN->ClientHardwareAddress, sizeof(MAC_Address_t));
|
|
DHCPHeaderOUT->Cookie = SwapEndian_32(DHCP_MAGIC_COOKIE);
|
|
|
|
/* Alter the incoming IP packet header so that the corrected IP source and destinations are used - this means that
|
|
when the response IP header is generated, it will use the corrected addresses and not the null/broatcast addresses */
|
|
IPHeaderIN->SourceAddress = ClientIPAddress;
|
|
IPHeaderIN->DestinationAddress = ServerIPAddress;
|
|
|
|
/* Process the incoming DHCP packet options */
|
|
while (DHCPOptionsINStart[0] != DHCP_OPTION_END)
|
|
{
|
|
/* Find the Message Type DHCP option, to determine the type of DHCP packet */
|
|
if (DHCPOptionsINStart[0] == DHCP_OPTION_MESSAGETYPE)
|
|
{
|
|
if ((DHCPOptionsINStart[2] == DHCP_MESSAGETYPE_DISCOVER) || (DHCPOptionsINStart[2] == DHCP_MESSAGETYPE_REQUEST))
|
|
{
|
|
/* Fill out the response DHCP packet options for a DHCP OFFER or ACK response */
|
|
|
|
*(DHCPOptionsOUTStart++) = DHCP_OPTION_MESSAGETYPE;
|
|
*(DHCPOptionsOUTStart++) = 1;
|
|
*(DHCPOptionsOUTStart++) = (DHCPOptionsINStart[2] == DHCP_MESSAGETYPE_DISCOVER) ? DHCP_MESSAGETYPE_OFFER
|
|
: DHCP_MESSAGETYPE_ACK;
|
|
|
|
*(DHCPOptionsOUTStart++) = DHCP_OPTION_SUBNETMASK;
|
|
*(DHCPOptionsOUTStart++) = sizeof(IP_Address_t);
|
|
*(DHCPOptionsOUTStart++) = 0xFF;
|
|
*(DHCPOptionsOUTStart++) = 0xFF;
|
|
*(DHCPOptionsOUTStart++) = 0xFF;
|
|
*(DHCPOptionsOUTStart++) = 0x00;
|
|
|
|
*(DHCPOptionsOUTStart++) = DHCP_OPTION_LEASETIME;
|
|
*(DHCPOptionsOUTStart++) = sizeof(uint32_t);
|
|
/* Lease Time 86400s (ONE_DAY) */
|
|
*(DHCPOptionsOUTStart++) = 0x00;
|
|
*(DHCPOptionsOUTStart++) = 0x01;
|
|
*(DHCPOptionsOUTStart++) = 0x51;
|
|
*(DHCPOptionsOUTStart++) = 0x80;
|
|
|
|
*(DHCPOptionsOUTStart++) = DHCP_OPTION_DHCPSERVER;
|
|
*(DHCPOptionsOUTStart++) = sizeof(IP_Address_t);
|
|
memcpy(DHCPOptionsOUTStart, &ServerIPAddress, sizeof(IP_Address_t));
|
|
DHCPOptionsOUTStart += sizeof(IP_Address_t);
|
|
|
|
*(DHCPOptionsOUTStart++) = DHCP_OPTION_END;
|
|
|
|
return (sizeof(DHCP_Header_t) + 18 + sizeof(IP_Address_t));
|
|
}
|
|
}
|
|
|
|
/* Go to the next DHCP option - skip one byte if option is a padding byte, else skip the complete option's size */
|
|
DHCPOptionsINStart += ((DHCPOptionsINStart[0] == DHCP_OPTION_PAD) ? 1 : (DHCPOptionsINStart[1] + 2));
|
|
}
|
|
|
|
return NO_RESPONSE;
|
|
}
|
|
|