266 lines
11 KiB
C
266 lines
11 KiB
C
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/*
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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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* DHCP Server Application. When connected to the uIP stack, this will send IP configuration settings to a
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* DHCP client on the network.
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*/
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#define INCLUDE_FROM_DHCPSERVERAPP_C
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#include "DHCPServerApp.h"
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#if defined(ENABLE_DHCP_SERVER) || defined(__DOXYGEN__)
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struct uip_conn* BroadcastConnection;
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uint8_t LeasedIPs[255 / 8];
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/** Initialization function for the DHCP server. */
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void DHCPServerApp_Init(void)
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{
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/* Listen on port 67 for DHCP server connections from hosts */
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uip_listen(HTONS(DHCP_SERVER_PORT));
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/* Create a new UDP connection to the DHCP server port for the DHCP solicitation */
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BroadcastConnection = uip_udp_new(&uip_broadcast_addr, HTONS(DHCP_CLIENT_PORT));
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/* If the connection was successfully created, bind it to the local DHCP client port */
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if (BroadcastConnection != NULL)
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uip_udp_bind(BroadcastConnection, HTONS(DHCP_SERVER_PORT));
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/* Set all IP addresses as unleased */
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memset(LeasedIPs, 0x00, sizeof(LeasedIPs));
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}
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/** uIP stack application callback for the DHCP server. This function must be called each time the TCP/IP stack
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* needs a UDP packet to be processed.
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*/
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void DHCPServerApp_Callback(void)
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{
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DHCP_Header_t* const AppData = (DHCP_Header_t*)uip_appdata;
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uint16_t AppDataSize = 0;
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/* Only process when new data arrives - don't retransmit lost packets */
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if (uip_newdata())
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{
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/* Get the DHCP message type (if present), otherwise early-abort */
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uint8_t DHCPMessageType;
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if (!(DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_MSG_TYPE, &DHCPMessageType)))
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return;
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uip_ipaddr_t Netmask, GatewayIPAddress, PreferredClientIP;
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struct uip_eth_addr RemoteMACAddress;
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uint32_t TransactionID;
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/* Get configured network mask, gateway IP and extract out DHCP transaction ID and remote IP */
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uip_getnetmask(&Netmask);
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uip_getdraddr(&GatewayIPAddress);
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memcpy(&RemoteMACAddress, &AppData->ClientHardwareAddress, sizeof(struct uip_eth_addr));
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TransactionID = AppData->TransactionID;
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/* Try to extract out the client's preferred IP address if it is indicated in the packet */
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if (!(DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_REQ_IPADDR, &PreferredClientIP)))
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memcpy(&PreferredClientIP, &uip_all_zeroes_addr, sizeof(uip_ipaddr_t));
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switch (DHCPMessageType)
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{
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case DHCP_DISCOVER:
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/* If no preference was made or the preferred IP is already taken, find a new address */
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if (DHCPServerApp_CheckIfIPLeased(&PreferredClientIP))
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DHCPServerApp_GetUnleasedIP(&PreferredClientIP);
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/* Create a new DHCP OFFER packet with the offered IP address */
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AppDataSize += DHCPServerApp_FillDHCPHeader(AppData, DHCP_OFFER, &RemoteMACAddress, &PreferredClientIP, TransactionID);
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/* Add network mask and router information to the list of DHCP OFFER packet options */
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AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_SUBNET_MASK,
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sizeof(uip_ipaddr_t), &Netmask);
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AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_ROUTER,
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sizeof(uip_ipaddr_t), &GatewayIPAddress);
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/* Send the DHCP OFFER packet */
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uip_poll_conn(BroadcastConnection);
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memcpy(&uip_udp_conn->ripaddr, &uip_broadcast_addr, sizeof(uip_ipaddr_t));
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uip_udp_send(AppDataSize);
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break;
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case DHCP_REQUEST:
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/* Check to see if the requested IP address has already been leased to a client */
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if (!(DHCPServerApp_CheckIfIPLeased(&PreferredClientIP)))
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{
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/* Create a new DHCP ACK packet to accept the IP address lease */
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AppDataSize += DHCPServerApp_FillDHCPHeader(AppData, DHCP_ACK, &RemoteMACAddress, &PreferredClientIP, TransactionID);
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/* Add network mask and router information to the list of DHCP ACK packet options */
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AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_SUBNET_MASK,
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sizeof(uip_ipaddr_t), &Netmask);
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AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_ROUTER,
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sizeof(uip_ipaddr_t), &GatewayIPAddress);
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/* Mark the requested IP as leased to a client */
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DHCPServerApp_LeaseIP(&PreferredClientIP);
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}
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else
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{
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/* Create a new DHCP NAK packet to reject the requested allocation */
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AppDataSize += DHCPServerApp_FillDHCPHeader(AppData, DHCP_NAK, &RemoteMACAddress, &uip_all_zeroes_addr, TransactionID);
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}
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/* Send the DHCP ACK or NAK packet */
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uip_poll_conn(BroadcastConnection);
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memcpy(&uip_udp_conn->ripaddr, &uip_broadcast_addr, sizeof(uip_ipaddr_t));
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uip_udp_send(AppDataSize);
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break;
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case DHCP_RELEASE:
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/* Mark the IP address as released in the allocation table */
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DHCPServerApp_UnleaseIP(&uip_udp_conn->ripaddr);
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break;
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}
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}
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}
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/** Fills the DHCP packet response with the appropriate BOOTP header for DHCP. This fills out all the required
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* fields, leaving only the additional DHCP options to be added to the packet before it is sent to the DHCP client.
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*
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* \param[out] DHCPHeader Location in the packet buffer where the BOOTP header should be written to
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* \param[in] DHCPMessageType DHCP Message type, such as DHCP_DISCOVER
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* \param[in] ClientHardwareAddress Client MAC address the created transaction should be directed to
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* \param[in] PreferredClientIP Preferred IP that should be given to the client if it is unallocated
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* \param[in] TransactionID Transaction ID the created transaction should be associated with
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*
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* \return Size in bytes of the created DHCP packet
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*/
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static uint16_t DHCPServerApp_FillDHCPHeader(DHCP_Header_t* const DHCPHeader,
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const uint8_t DHCPMessageType,
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const struct uip_eth_addr* const ClientHardwareAddress,
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const uip_ipaddr_t* const PreferredClientIP,
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const uint32_t TransactionID)
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{
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/* Erase existing packet data so that we start will all 0x00 DHCP header data */
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memset(DHCPHeader, 0, sizeof(DHCP_Header_t));
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DHCPHeader->Operation = DHCPMessageType;
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DHCPHeader->HardwareType = DHCP_HTYPE_ETHERNET;
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DHCPHeader->HardwareAddressLength = sizeof(MACAddress);
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DHCPHeader->Hops = 0;
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DHCPHeader->TransactionID = TransactionID;
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DHCPHeader->ElapsedSeconds = 0;
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DHCPHeader->Flags = 0;
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memcpy(&DHCPHeader->NextServerIP, &uip_hostaddr, sizeof(uip_ipaddr_t));
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memcpy(&DHCPHeader->YourIP, PreferredClientIP, sizeof(uip_ipaddr_t));
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memcpy(&DHCPHeader->ClientHardwareAddress, ClientHardwareAddress, sizeof(struct uip_eth_addr));
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DHCPHeader->Cookie = DHCP_MAGIC_COOKIE;
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/* Add a DHCP message type and terminator options to the start of the DHCP options field */
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DHCPHeader->Options[0] = DHCP_OPTION_MSG_TYPE;
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DHCPHeader->Options[1] = 1;
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DHCPHeader->Options[2] = DHCPMessageType;
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DHCPHeader->Options[3] = DHCP_OPTION_END;
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/* Calculate the total number of bytes added to the outgoing packet */
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return (sizeof(DHCP_Header_t) + 4);
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}
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/** Checks to see if the nominated IP address has already been allocated to a client.
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*
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* \param[in] IPAddress IP Address whose lease status should be checked
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*
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* \pre The IP address must be within the same /24 subnet as the virtual webserver.
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*
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* \return Boolean \c true if the IP has already been leased to a client, \c false otherwise.
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*/
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static bool DHCPServerApp_CheckIfIPLeased(const uip_ipaddr_t* const IPAddress)
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{
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uint8_t Byte = (IPAddress->u8[3] / 8);
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uint8_t Mask = (1 << (IPAddress->u8[3] % 8));
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/* Make sure that the requested IP address isn't already leased to the virtual server or another client */
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if (IPAddress->u8[3] && !(IPAddress->u8[3] == uip_hostaddr.u8[3]) && !(LeasedIPs[Byte] & Mask))
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return false;
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else
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return true;
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}
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/** Retrieves the next unleased IP in the IP address pool.
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*
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* \param[out] NewIPAddress Location where the generated IP Address should be stored
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*/
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static void DHCPServerApp_GetUnleasedIP(uip_ipaddr_t* const NewIPAddress)
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{
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uip_ipaddr_copy(NewIPAddress, &uip_hostaddr);
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/** Look through the current subnet, skipping the broadcast and zero IP addresses */
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for (uint8_t IP = 1; IP < 254; IP++)
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{
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/* Update new IP address to lease with the current IP address to test */
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NewIPAddress->u8[3] = IP;
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/* If we've found an unleased IP, abort with the updated IP stored for the called */
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if (!(DHCPServerApp_CheckIfIPLeased(NewIPAddress)))
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return;
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}
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}
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/** Marks the given IP Address as leased in the address pool, so that it will not be
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* allocated to another client unless it is first released.
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*
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* \param[in] IPAddress IP Address to mark as leased
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*
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* \pre The IP address must be within the same /24 subnet as the virtual webserver.
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*/
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static void DHCPServerApp_LeaseIP(const uip_ipaddr_t* const IPAddress)
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{
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uint8_t Byte = (IPAddress->u8[3] / 8);
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uint8_t Mask = (1 << (IPAddress->u8[3] % 8));
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/* Mark the IP address as leased in the allocation table */
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LeasedIPs[Byte] |= Mask;
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}
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/** Marks the given IP Address as not leased in the address pool, so that it can be
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* allocated to another client upon request.
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*
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* \param[in] IPAddress IP Address to mark as not leased
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*
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* \pre The IP address must be within the same /24 subnet as the virtual webserver.
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*/
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static void DHCPServerApp_UnleaseIP(const uip_ipaddr_t* const IPAddress)
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{
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uint8_t Byte = (IPAddress->u8[3] / 8);
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uint8_t Mask = (1 << (IPAddress->u8[3] % 8));
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/* Mark the IP address as unleased in the allocation table */
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LeasedIPs[Byte] &= ~Mask;
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}
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#endif
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