/*
 * \brief  DHCP related definitions
 * \author Stefan Kalkowski
 * \date   2010-08-19
 */

/*
 * Copyright (C) 2010-2013 Genode Labs GmbH
 *
 * This file is part of the Genode OS framework, which is distributed
 * under the terms of the GNU General Public License version 2.
 */

#ifndef _DHCP_H_
#define _DHCP_H_

/* Genode */
#include <base/exception.h>
#include <base/stdint.h>

#include <util/endian.h>
#include <net/ethernet.h>
#include <net/ipv4.h>
#include <net/udp.h>

namespace Net {

	/**
	 * The data-layout of this class conforms to an DHCP packet (RFC 2131).
	 *
	 * DHCP packet layout:
	 *
	 *  ===================================
	 * | 1 byte | 1 byte | 1 byte | 1 byte |
	 *  ===================================
	 * |   op   |  htype |  hlen  |  hops  |
	 *  -----------------------------------
	 * |       connection-id (xid)         |
	 *  -----------------------------------
	 * |    seconds      |      flags      |
	 *  -----------------------------------
	 * |         client-ip-address         |
	 *  -----------------------------------
	 * |           your-ip-address         |
	 *  -----------------------------------
	 * |         server-ip-address         |
	 *  -----------------------------------
	 * |       relay-agent-ip-address      |
	 *  -----------------------------------
	 * |          client-hw-address        |
	 * |             (16 bytes)            |
	 *  -----------------------------------
	 * |              sname                |
	 * |            (64 bytes)             |
	 *  -----------------------------------
	 * |               file                |
	 * |            (128 bytes)            |
	 *  -----------------------------------
	 * |              options              |
	 * |      (312 bytes, optional)        |
	 *  -----------------------------------
	 */
	class Dhcp_packet
	{
		public:

			class No_dhcp_packet : Genode::Exception {};


			class Client_hw_address
			{
				public:
					Genode::uint8_t addr[16];
			};

		private:

			/************************
			 ** DHCP packet fields **
			 ************************/

			Genode::uint8_t   _op;
			Genode::uint8_t   _htype;
			Genode::uint8_t   _hlen;
			Genode::uint8_t   _hops;
			Genode::uint32_t  _xid;
			Genode::uint16_t  _secs;
			Genode::uint16_t  _flags;
			Genode::uint8_t   _ciaddr[Ipv4_packet::ADDR_LEN];
			Genode::uint8_t   _yiaddr[Ipv4_packet::ADDR_LEN];
			Genode::uint8_t   _siaddr[Ipv4_packet::ADDR_LEN];
			Genode::uint8_t   _giaddr[Ipv4_packet::ADDR_LEN];
			Client_hw_address _chaddr;
			Genode::uint8_t   _sname[64];
			Genode::uint8_t   _file[128];
			Genode::uint32_t  _magic_cookie;
			Genode::uint8_t   _opts[0];

			enum Flag {
				BROADCAST = 0x80
			};

		public:

			/**
			 * This class represents the data layout of an DHCP option.
			 */
			class Option
			{
				private:

					Genode::uint8_t _code;
					Genode::uint8_t _len;
					Genode::uint8_t _value[0];

				public:

					Option() {}

					Genode::uint8_t code()   { return _code;  }
					Genode::size_t  length() { return _len;   }
					void*           value()  { return _value; }

					/**
					 * Placement new.
					 */
					void * operator new(Genode::size_t size, void* addr) {
						return addr; }
			} __attribute__((packed));


			enum Opcode {
				REQUEST = 1,
				REPLY   = 2,
				INVALID
			};

			enum Udp_port {
				BOOTPS = 67,
				BOOTPC = 68
			};

			enum Option_type {
				REQ_IP_ADDR    = 50,
				IP_LEASE_TIME  = 51,
				OPT_OVERLOAD   = 52,
				MSG_TYPE       = 53,
				SRV_ID         = 54,
				REQ_PARAMETER  = 55,
				MESSAGE        = 56,
				MAX_MSG_SZ     = 57,
				RENEWAL        = 58,
				REBINDING      = 59,
				VENDOR         = 60,
				CLI_ID         = 61,
				TFTP_SRV_NAME  = 66,
				BOOT_FILE      = 67,
				END            = 255
			};

			enum Message_type {
				DHCP_DISCOVER  = 1,
				DHCP_OFFER     = 2,
				DHCP_REQUEST   = 3,
				DHCP_DECLINE   = 4,
				DHCP_ACK       = 5,
				DHCP_NAK       = 6,
				DHCP_RELEASE   = 7,
				DHCP_INFORM    = 8
			};


			/*****************
			 ** Constructor **
			 *****************/

			Dhcp_packet(Genode::size_t size) {
				/* dhcp packet needs to fit in */
				if (size < sizeof(Dhcp_packet))
					throw No_dhcp_packet();
			}


			/*******************************
			 ** DHCP field read-accessors **
			 *******************************/

			Genode::uint8_t   op()    { return _op;          }
			Genode::uint8_t   htype() { return _htype;       }
			Genode::uint8_t   hlen()  { return _hlen;        }
			Genode::uint8_t   hops()  { return _hops;        }
			Genode::uint32_t  xid()   { return bswap(_xid);  }
			Genode::uint16_t  secs()  { return bswap(_secs); }

			bool broadcast() { return _flags & BROADCAST;    }

			Ipv4_packet::Ipv4_address ciaddr() {
				return Ipv4_packet::Ipv4_address(&_ciaddr);  }
			Ipv4_packet::Ipv4_address yiaddr() {
				return Ipv4_packet::Ipv4_address(&_yiaddr);  }
			Ipv4_packet::Ipv4_address siaddr() {
				return Ipv4_packet::Ipv4_address(&_siaddr);  }
			Ipv4_packet::Ipv4_address giaddr() {
				return Ipv4_packet::Ipv4_address(&_giaddr);  }

			Ethernet_frame::Mac_address client_mac() {
				return Ethernet_frame::Mac_address(&_chaddr); }

			const char* server_name()  { return (const char*) &_sname; }
			const char* file()         { return (const char*) &_file;  }

			Option *option(Option_type op)
			{
				void *ptr = &_opts;
				while (true) {
					Option *ext = new (ptr) Option();
					if (ext->code() == op)
						return ext;
					if (ext->code() == END || ext->code() == 0)
						break;
					ptr = ext + ext->length();
				}
				return 0;
			}


			/*******************************
			 ** DHCP field write-accessors **
			 *******************************/

			void op(Genode::uint8_t op)       { _op = op;             }
			void htype(Genode::uint8_t htype) { _htype = htype;       }
			void hlen(Genode::uint8_t hlen)   { _hlen = hlen;         }
			void hops(Genode::uint8_t hops)   { _hops = hops;         }
			void xid(Genode::uint32_t xid)    { _xid = bswap(_xid);   }
			void secs(Genode::uint16_t secs)  { _secs = bswap(_secs); }

			void broadcast(bool broadcast) {
				_flags = broadcast ? BROADCAST : 0;       }

			void ciaddr(Ipv4_packet::Ipv4_address ciaddr) {
				ciaddr.copy(&_ciaddr); }
			void yiaddr(Ipv4_packet::Ipv4_address yiaddr) {
				yiaddr.copy(&_yiaddr); }
			void siaddr(Ipv4_packet::Ipv4_address siaddr) {
				siaddr.copy(&_siaddr); }
			void giaddr(Ipv4_packet::Ipv4_address giaddr) {
				giaddr.copy(&_giaddr); }

			void client_mac(Ethernet_frame::Mac_address mac) {
				mac.copy(&_chaddr); }


			/***************************
			 ** Convenience functions **
			 ***************************/

			static bool is_dhcp(Udp_packet *udp)
			{
				return ((udp->src_port() == Dhcp_packet::BOOTPC ||
				         udp->src_port() == Dhcp_packet::BOOTPS) &&
				        (udp->dst_port() == Dhcp_packet::BOOTPC ||
				         udp->dst_port() == Dhcp_packet::BOOTPS));
			}


			/***************
			 ** Operators **
			 ***************/

			/**
			 * Placement new.
			 */
			void * operator new(Genode::size_t size, void* addr) {
				return addr; }

	} __attribute__((packed));
}

#endif /* _DHCP_H_ */