using System;
using System.Net.NetworkInformation;
using SharpPcap.Packets;
using SharpPcap.Util;

/*
Copyright (c) 2006 Tamir Gal, http://www.tamirgal.com, All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice,
        this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright 
        notice, this list of conditions and the following disclaimer in 
        the documentation and/or other materials provided with the distribution.

    3. The names of the authors may not be used to endorse or promote products
        derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR
OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

namespace SharpPcap.Protocols
{
    /// <summary>
    /// Resolves MAC addresses from IP addresses using the Address Resolution Protocol (ARP)
    /// </summary>
    public class ARP
    {
        private System.Net.IPAddress    _localIP;
        private string                  _deviceName;

        /// <summary>
        /// Constructs a new ARP Resolver
        /// </summary>
        public ARP()
        {
        }

        /// <summary>
        /// Constructs a new ARP Resolver
        /// </summary>
        /// <param name="deviceName">The name of the network device on which this resolver sends its ARP packets</param>
        public ARP(string deviceName)
        {
            DeviceName=deviceName;
        }

        private PhysicalAddress          _localMAC;

        /// <summary>
        /// The source MAC address to be used for ARP requests.
        /// If null, the local device MAC address is used
        /// </summary>
        public PhysicalAddress LocalMAC
        {
            get
            {
                return _localMAC;
            }
            set
            {
                _localMAC = value;
            }
        }

        /// <summary>
        /// The source IP address to be used for ARP requests.
        /// If null, the local device IP address is used
        /// </summary>
        public System.Net.IPAddress LocalIP
        {
            get
            {
                return _localIP;
            }

            set
            {
                _localIP = value;
            }
        }

        /// <summary>
        /// The default device name on which to send ARP requests
        /// </summary>
        public string DeviceName
        {
            get
            {
                return _deviceName;
            }
            set
            {
                _deviceName = value;
            }
        }

        /// <summary>
        /// Resolves the MAC address of the specified IP address. The 'DeviceName' propery must be set
        /// prior to using this method.
        /// </summary>
        /// <param name="destIP">The IP address to resolve</param>
        /// <returns>The MAC address that matches to the given IP address</returns>
        public PhysicalAddress Resolve(System.Net.IPAddress destIP)
        {
            if(DeviceName==null)
                throw new Exception("Can't resolve host: A network device must be specified");

            return Resolve(destIP, DeviceName);
        }

        /// <summary>
        /// Resolves the MAC address of the specified IP address
        /// </summary>
        /// <param name="destIP">The IP address to resolve</param>
        /// <param name="deviceName">The local network device name on which to send the ARP request</param>
        /// <returns>The MAC address that matches to the given IP address</returns>
        public PhysicalAddress Resolve(System.Net.IPAddress destIP, string deviceName)
        {
            PhysicalAddress localMAC = LocalMAC;
            System.Net.IPAddress localIP = LocalIP;
            //NetworkDevice device = new NetworkDevice(DeviceName);
            PcapDevice device = Pcap.GetPcapDevice(DeviceName);

            //FIXME: PcapDevices don't have IpAddress
            //       These were present under Windows specific network adapters
            //       and may be present in pcap in the future with pcap-ng
            // if no local ip address is specified use the one from the
            // local device
#if false
            if(localIP == null)
                localIP = device.IpAddress;
#endif

            // if no local mac address is specified use the one from the device
            if(LocalMAC == null)
                localMAC = device.Interface.MacAddress;

            //Build a new ARP request packet
            ARPPacket request = BuildRequest(destIP, localMAC, localIP);

            //create a "tcpdump" filter for allowing only arp replies to be read
            String arpFilter = "arp and ether dst " + localMAC.ToString();

            //open the device with 20ms timeout
            device.Open(true, 20);
            //set the filter
            device.SetFilter(arpFilter);
            //inject the packet to the wire
            device.SendPacket(request);

            ARPPacket reply;

            while(true)
            {
                //read the next packet from the network
                reply = (ARPPacket)device.GetNextPacket();
                if(reply==null)continue;
                
                //if this is the reply we're looking for, stop
                if(reply.ARPSenderProtoAddress.Equals(destIP))
                {
                    break;
                }
            }
            //free the device
            device.Close();
            //return the resolved MAC address
            return reply.ARPSenderHwAddress;
        }

        private ARPPacket BuildRequest(System.Net.IPAddress destIP,
                                       PhysicalAddress localMAC,
                                       System.Net.IPAddress localIP)
        {
            ARPPacket arp = BuildARP(localMAC, localIP);
            arp.ARPOperation = ARPFields_Fields.ARP_OP_REQ_CODE;
            arp.ARPTargetHwAddress = PhysicalAddress.Parse("00-00-00-00-00-00");
            arp.ARPTargetProtoAddress = destIP;
            arp.DestinationHwAddress = PhysicalAddress.Parse("FF-FF-FF-FF-FF-FF");
            return arp;
        }

        private ARPPacket BuildARP(PhysicalAddress localMAC, System.Net.IPAddress localIP)
        {
            ARPPacket arp = new ARPPacket(14, new byte[60]);
            // arp fields
            arp.ARPHwLength = 6;
            arp.ARPHwType = ARPFields_Fields.ARP_ETH_ADDR_CODE;
            arp.ARPProtocolLength = 4;
            arp.ARPProtocolType = ARPFields_Fields.ARP_IP_ADDR_CODE;
            arp.ARPSenderHwAddress = localMAC;
            arp.ARPSenderProtoAddress = localIP;
            // ether fields
            arp.SourceHwAddress = localMAC;
            arp.EthernetProtocol = EthernetPacket.EtherType.ARP;
            return arp;
        }
    }
}