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Diffstat (limited to 'Projects/Webserver/Lib/DHCPServerApp.c')
| -rw-r--r-- | Projects/Webserver/Lib/DHCPServerApp.c | 265 |
1 files changed, 265 insertions, 0 deletions
diff --git a/Projects/Webserver/Lib/DHCPServerApp.c b/Projects/Webserver/Lib/DHCPServerApp.c new file mode 100644 index 0000000000..fea54ddb0e --- /dev/null +++ b/Projects/Webserver/Lib/DHCPServerApp.c @@ -0,0 +1,265 @@ +/* + 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 + * + * DHCP Server Application. When connected to the uIP stack, this will send IP configuration settings to a + * DHCP client on the network. + */ + +#define INCLUDE_FROM_DHCPSERVERAPP_C +#include "DHCPServerApp.h" + +#if defined(ENABLE_DHCP_SERVER) || defined(__DOXYGEN__) + +struct uip_conn* BroadcastConnection; + +uint8_t LeasedIPs[255 / 8]; + +/** Initialization function for the DHCP server. */ +void DHCPServerApp_Init(void) +{ + /* Listen on port 67 for DHCP server connections from hosts */ + uip_listen(HTONS(DHCP_SERVER_PORT)); + + /* Create a new UDP connection to the DHCP server port for the DHCP solicitation */ + struct uip_udp_conn* BroadcastConnection = uip_udp_new(&uip_broadcast_addr, HTONS(DHCP_CLIENT_PORT)); + + /* If the connection was successfully created, bind it to the local DHCP client port */ + if (BroadcastConnection != NULL) + uip_udp_bind(BroadcastConnection, HTONS(DHCP_SERVER_PORT)); + + /* Set all IP addresses as unleased */ + memset(LeasedIPs, 0x00, sizeof(LeasedIPs)); +} + +/** uIP stack application callback for the DHCP server. This function must be called each time the TCP/IP stack + * needs a UDP packet to be processed. + */ +void DHCPServerApp_Callback(void) +{ + DHCP_Header_t* const AppData = (DHCP_Header_t*)uip_appdata; + uint16_t AppDataSize = 0; + + /* Only process when new data arrives - don't retransmit lost packets */ + if (uip_newdata()) + { + /* Get the DHCP message type (if present), otherwise early-abort */ + uint8_t DHCPMessageType; + if (!(DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_MSG_TYPE, &DHCPMessageType))) + return; + + uip_ipaddr_t Netmask, GatewayIPAddress, PreferredClientIP; + struct uip_eth_addr RemoteMACAddress; + uint32_t TransactionID; + + /* Get configured network mask, gateway IP and extract out DHCP transaction ID and remote IP */ + uip_getnetmask(&Netmask); + uip_getdraddr(&GatewayIPAddress); + memcpy(&RemoteMACAddress, &AppData->ClientHardwareAddress, sizeof(struct uip_eth_addr)); + TransactionID = AppData->TransactionID; + + /* Try to extract out the client's preferred IP address if it is indicated in the packet */ + if (!(DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_REQ_IPADDR, &PreferredClientIP))) + memcpy(&PreferredClientIP, &uip_all_zeroes_addr, sizeof(uip_ipaddr_t)); + + switch (DHCPMessageType) + { + case DHCP_DISCOVER: + /* If no preference was made or the preferred IP is already taken, find a new address */ + if (DHCPServerApp_CheckIfIPLeased(&PreferredClientIP)) + DHCPServerApp_GetUnleasedIP(&PreferredClientIP); + + /* Create a new DHCP OFFER packet with the offered IP address */ + AppDataSize += DHCPServerApp_FillDHCPHeader(AppData, DHCP_OFFER, &RemoteMACAddress, &PreferredClientIP, TransactionID); + + /* Add network mask and router information to the list of DHCP OFFER packet options */ + AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_SUBNET_MASK, + sizeof(uip_ipaddr_t), &Netmask); + AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_ROUTER, + sizeof(uip_ipaddr_t), &GatewayIPAddress); + + /* Send the DHCP OFFER packet */ + uip_poll_conn(BroadcastConnection); + memcpy(&uip_udp_conn->ripaddr, &uip_broadcast_addr, sizeof(uip_ipaddr_t)); + uip_udp_send(AppDataSize); + + break; + case DHCP_REQUEST: + /* Check to see if the requested IP address has already been leased to a client */ + if (!(DHCPServerApp_CheckIfIPLeased(&PreferredClientIP))) + { + /* Create a new DHCP ACK packet to accept the IP address lease */ + AppDataSize += DHCPServerApp_FillDHCPHeader(AppData, DHCP_ACK, &RemoteMACAddress, &PreferredClientIP, TransactionID); + + /* Add network mask and router information to the list of DHCP ACK packet options */ + AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_SUBNET_MASK, + sizeof(uip_ipaddr_t), &Netmask); + AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_ROUTER, + sizeof(uip_ipaddr_t), &GatewayIPAddress); + + /* Mark the requested IP as leased to a client */ + DHCPServerApp_LeaseIP(&PreferredClientIP); + } + else + { + /* Create a new DHCP NAK packet to reject the requested allocation */ + AppDataSize += DHCPServerApp_FillDHCPHeader(AppData, DHCP_NAK, &RemoteMACAddress, &uip_all_zeroes_addr, TransactionID); + } + + /* Send the DHCP ACK or NAK packet */ + uip_poll_conn(BroadcastConnection); + memcpy(&uip_udp_conn->ripaddr, &uip_broadcast_addr, sizeof(uip_ipaddr_t)); + uip_udp_send(AppDataSize); + + break; + case DHCP_RELEASE: + /* Mark the IP address as released in the allocation table */ + DHCPServerApp_UnleaseIP(&uip_udp_conn->ripaddr); + break; + } + } +} + +/** Fills the DHCP packet response with the appropriate BOOTP header for DHCP. This fills out all the required + * fields, leaving only the additional DHCP options to be added to the packet before it is sent to the DHCP client. + * + * \param[out] DHCPHeader Location in the packet buffer where the BOOTP header should be written to + * \param[in] DHCPMessageType DHCP Message type, such as DHCP_DISCOVER + * \param[in] ClientHardwareAddress Client MAC address the created transaction should be directed to + * \param[in] PreferredClientIP Preferred IP that should be given to the client if it is unallocated + * \param[in] TransactionID Transaction ID the created transaction should be associated with + * + * \return Size in bytes of the created DHCP packet + */ +static uint16_t DHCPServerApp_FillDHCPHeader(DHCP_Header_t* const DHCPHeader, + const uint8_t DHCPMessageType, + const struct uip_eth_addr* const ClientHardwareAddress, + const uip_ipaddr_t* const PreferredClientIP, + const uint32_t TransactionID) +{ + /* Erase existing packet data so that we start will all 0x00 DHCP header data */ + memset(DHCPHeader, 0, sizeof(DHCP_Header_t)); + + DHCPHeader->Operation = DHCPMessageType; + DHCPHeader->HardwareType = DHCP_HTYPE_ETHERNET; + DHCPHeader->HardwareAddressLength = sizeof(MACAddress); + DHCPHeader->Hops = 0; + DHCPHeader->TransactionID = TransactionID; + DHCPHeader->ElapsedSeconds = 0; + DHCPHeader->Flags = 0; + memcpy(&DHCPHeader->NextServerIP, &uip_hostaddr, sizeof(uip_ipaddr_t)); + memcpy(&DHCPHeader->YourIP, PreferredClientIP, sizeof(uip_ipaddr_t)); + memcpy(&DHCPHeader->ClientHardwareAddress, ClientHardwareAddress, sizeof(struct uip_eth_addr)); + DHCPHeader->Cookie = DHCP_MAGIC_COOKIE; + + /* Add a DHCP message type and terminator options to the start of the DHCP options field */ + DHCPHeader->Options[0] = DHCP_OPTION_MSG_TYPE; + DHCPHeader->Options[1] = 1; + DHCPHeader->Options[2] = DHCPMessageType; + DHCPHeader->Options[3] = DHCP_OPTION_END; + + /* Calculate the total number of bytes added to the outgoing packet */ + return (sizeof(DHCP_Header_t) + 4); +} + +/** Checks to see if the nominated IP address has already been allocated to a client. + * + * \param[in] IPAddress IP Address whose lease status should be checked + * + * \pre The IP address must be within the same /24 subnet as the virtual webserver. + * + * \return Boolean \c true if the IP has already been leased to a client, \c false otherwise. + */ +static bool DHCPServerApp_CheckIfIPLeased(const uip_ipaddr_t* const IPAddress) +{ + uint8_t Byte = (IPAddress->u8[3] / 8); + uint8_t Mask = (1 << (IPAddress->u8[3] % 8)); + + /* Make sure that the requested IP address isn't already leased to the virtual server or another client */ + if (IPAddress->u8[3] && !(IPAddress->u8[3] == uip_hostaddr.u8[3]) && !(LeasedIPs[Byte] & Mask)) + return false; + else + return true; +} + +/** Retrieves the next unleased IP in the IP address pool. + * + * \param[out] NewIPAddress Location where the generated IP Address should be stored + */ +static void DHCPServerApp_GetUnleasedIP(uip_ipaddr_t* const NewIPAddress) +{ + uip_ipaddr_copy(NewIPAddress, &uip_hostaddr); + + /** Look through the current subnet, skipping the broadcast and zero IP addresses */ + for (uint8_t IP = 1; IP < 254; IP++) + { + /* Update new IP address to lease with the current IP address to test */ + NewIPAddress->u8[3] = IP; + + /* If we've found an unleased IP, abort with the updated IP stored for the called */ + if (!(DHCPServerApp_CheckIfIPLeased(NewIPAddress))) + return; + } +} + +/** Marks the given IP Address as leased in the address pool, so that it will not be + * allocated to another client unless it is first released. + * + * \param[in] IPAddress IP Address to mark as leased + * + * \pre The IP address must be within the same /24 subnet as the virtual webserver. + */ +static void DHCPServerApp_LeaseIP(const uip_ipaddr_t* const IPAddress) +{ + uint8_t Byte = (IPAddress->u8[3] / 8); + uint8_t Mask = (1 << (IPAddress->u8[3] % 8)); + + /* Mark the IP address as leased in the allocation table */ + LeasedIPs[Byte] |= Mask; +} + +/** Marks the given IP Address as not leased in the address pool, so that it can be + * allocated to another client upon request. + * + * \param[in] IPAddress IP Address to mark as not leased + * + * \pre The IP address must be within the same /24 subnet as the virtual webserver. + */ +static void DHCPServerApp_UnleaseIP(const uip_ipaddr_t* const IPAddress) +{ + uint8_t Byte = (IPAddress->u8[3] / 8); + uint8_t Mask = (1 << (IPAddress->u8[3] % 8)); + + /* Mark the IP address as unleased in the allocation table */ + LeasedIPs[Byte] &= ~Mask; +} +#endif + |