/// <summary>
/// Resolves the specified IPv4 destination address to a physical
/// address and hands the specified IPv4 packet down to the link
/// layer.
/// </summary>
/// <param name="ifc">The interface through which to output the
/// data.</param>
/// <param name="destination">The logical address of the destination
/// host, which can different from the final destination address
/// contained in the IP packet.</param>
/// <param name="packet">The IPv4 packet to transmit.</param>
/// <exception cref="ArgumentNullException">Thrown if any of the arguments
/// is null.</exception>
void Output(Interface ifc, IpAddress destination, IpPacket packet)
{
ifc.ThrowIfNull("ifc");
destination.ThrowIfNull("destination");
packet.ThrowIfNull("packet");
// Translate IP address into MAC-Address.
var macDestination = arp.Lookup(ifc, destination);
// IP address is not in our ARP table.
if (macDestination == null)
{
// Put packet on hold until the MAC-48 destination address has
// been figured out.
WaitingPacketsOf(ifc).Add(
new Tuple <IpAddress, IpPacket>(destination, packet));
WriteLine(ifc.FullName + " is putting IP packet on-hold due to pending ARP request.");
// Schedule a new ARP request.
arp.Resolve(ifc, destination);
}
else
{
WriteLine(ifc.FullName + " is queueing IP packet for " + destination);
Output(ifc, macDestination, packet);
}
}
/// <summary>
/// Private constructor used for deserialization.
/// </summary>
private IpPacket(IpVersion version, byte ihl, byte dscp, ushort totalLength,
ushort identification, IpFlag flags, ushort fragmentOffset,
byte ttl, IpProtocol protocol, ushort checksum, IpAddress source,
IpAddress destination)
{
destination.ThrowIfNull("destination");
source.ThrowIfNull("source");
if (ihl > 0x0F)
{
throw new ArgumentException("The Internet Header Length field must " +
"be in the range from 0 to 15.", nameof(ihl));
}
if (fragmentOffset > 0x1FFF)
{
throw new ArgumentException("The Fragment Offset field must be in " +
"the range from 0 to 8191.", nameof(fragmentOffset));
}
Version = version;
Ihl = ihl;
Dscp = dscp;
TotalLength = totalLength;
Identification = identification;
Flags = flags;
FragmentOffset = fragmentOffset;
TimeToLive = ttl;
Protocol = protocol;
Checksum = checksum;
Source = source;
Destination = destination;
Data = new byte[0];
}
/// <summary>
/// Initializes a new instance of the IpPacket class using the specified
/// values.
/// </summary>
/// <param name="destination">The IPv4 address of the destination
/// host.</param>
/// <param name="source">The IPv4 address of the sending host.</param>
/// <param name="type">The type of the transport protocol encapsulated in
/// the IP packet's data section.</param>
/// <param name="fragmentOffset">The fragment offset of the packet.</param>
/// <param name="data">The transport data to transfer as part of the IP
/// packet.</param>
/// <param name="ihl">The Internet Header Length.</param>
/// <param name="dscp">The Differentiated Services Code Point.</param>
/// <param name="ttl">The time-to-live of the IP packet.</param>
/// <param name="identification">The idenfication used for uniquely identifying
/// fragments of a fragmented IP packet.</param>
/// <param name="flags">The flags set on the IP packet.</param>
/// <exception cref="ArgumentNullException">Thrown if any of the arguments
/// is null.</exception>
public IpPacket(IpAddress destination, IpAddress source,
IpProtocol type, byte ihl, byte dscp, byte ttl, ushort identification,
IpFlag flags, ushort fragmentOffset, byte[] data)
{
destination.ThrowIfNull("destination");
source.ThrowIfNull("source");
data.ThrowIfNull("data");
if (ihl > 0x0F)
{
throw new ArgumentException("The Internet Header Length field must " +
"be in the range from 0 to 15.", nameof(ihl));
}
if (fragmentOffset > 0x1FFF)
{
throw new ArgumentException("The Fragment Offset field must be in " +
"the range from 0 to 8191.", nameof(fragmentOffset));
}
Version = IpVersion.Ipv4;
Ihl = ihl;
Dscp = dscp;
Identification = identification;
Flags = flags;
FragmentOffset = fragmentOffset;
TimeToLive = ttl;
Protocol = type;
Source = source;
Destination = destination;
Data = data;
TotalLength = (ushort)(20 + Data.Length);
Checksum = ComputeChecksum(this);
}
/// <summary>
/// Sends the specified ICMP packet to the specified destination host.
/// </summary>
/// <param name="ifc">The interface through which the ICMP packet
/// should be sent.</param>
/// <param name="destination">The IP address of the destination host
/// of the ICMP packet.</param>
/// <param name="packet">The ICMP packet to send.</param>
/// <exception cref="ArgumentNullException">Thrown if any of the arguments
/// is null.</exception>
void SendIcmp(Interface ifc, IpAddress destination, IcmpPacket packet)
{
ifc.ThrowIfNull("ifc");
destination.ThrowIfNull("destination");
packet.ThrowIfNull("packet");
Simulation.WriteLine(OutputLevel.Icmp, ifc.FullName + " is queueing a " +
packet.Type + " ICMP packet to " + destination, ConsoleColor.Magenta);
Output(ifc, destination, packet.Serialize(), IpProtocol.Icmp);
}
/// <summary>
/// Initializes a new instance of the IpPacket class using the specified
/// values.
/// </summary>
/// <param name="destination">The IPv4 address of the destination
/// host.</param>
/// <param name="source">The IPv4 address of the sending host.</param>
/// <param name="type">The type of the transport protocol encapsulated in
/// the IP packet's data section.</param>
/// <param name="data">The transport data to transfer as part of the IP
/// packet.</param>
/// <exception cref="ArgumentNullException">Thrown if any of the arguments
/// is null.</exception>
public IpPacket(IpAddress destination, IpAddress source,
IpProtocol type, byte[] data)
{
destination.ThrowIfNull("destination");
source.ThrowIfNull("source");
data.ThrowIfNull("data");
Destination = destination;
Source = source;
Protocol = type;
Data = data;
TimeToLive = 64;
Ihl = 5;
TotalLength = (ushort)(20 + Data.Length);
Version = IpVersion.Ipv4;
Checksum = ComputeChecksum(this);
}
/// <summary>
/// Wraps the specified higher-level data into IP packets and
/// transmits them to the specified destination.
/// </summary>
/// <param name="ifc">The interface through which to output the data.</param>
/// <param name="destination">The logical address of the destination
/// host.</param>
/// <param name="data">The higher-level data to transmit.</param>
/// <param name="type">The type of the higher-level data.</param>
/// <exception cref="ArgumentNullException">Thrown if any of the arguments
/// is null.</exception>
/// <remarks>This API is exposed to the next higher-up layer.</remarks>
public void Output(Interface ifc, IpAddress destination, byte[] data,
IpProtocol type)
{
ifc.ThrowIfNull("ifc");
destination.ThrowIfNull("destination");
data.ThrowIfNull("data");
// Construct IP packets of the size of the MTU of the data-link.
var maxDataSize = ifc.MaximumTransmissionUnit - 20;
var numPackets = (int)Math.Ceiling(data.Length / (double)maxDataSize);
var sameSubnet = (destination & ifc.Netmask) == (ifc.IpAddress & ifc.Netmask);
for (int i = 0, index = 0; i < numPackets; i++)
{
var numBytes = Math.Min(maxDataSize, data.Length - index);
var packetData = new byte[numBytes];
Array.Copy(data, index, packetData, 0, numBytes);
index = index + numBytes;
// Construct the packet.
var packet = new IpPacket(destination, ifc.IpAddress, type, packetData);
// If source and destination are in the same subnet, we can deliver the
// packet directly. Otherwise send it to the configured default gateway.
Output(ifc, sameSubnet ? destination : ifc.Gateway, packet);
}
}
/// <summary>
/// Initializes the interface.
/// </summary>
/// <param name="nic">The network interface card (NIC) this interface
/// represents.</param>
/// <param name="name">A unique name (such as eth0) for identifing the
/// interface.</param>
/// <param name="ipAddress">The IPv4 address to associate with this
/// interface.</param>
/// <param name="netmask">The subnetmask to assign to this interface.</param>
/// <param name="gateway">The IPv4 address of the default gateway to
/// configure this interface with.</param>
void Init(Nic nic, string name, IpAddress ipAddress, IpAddress netmask,
IpAddress gateway) {
nic.ThrowIfNull("nic");
name.ThrowIfNull("name");
ipAddress.ThrowIfNull("ipAddress");
netmask.ThrowIfNull("netmask");
Nic = nic;
Name = name;
IpAddress = ipAddress;
Netmask = netmask;
Gateway = gateway;
Nic.Interrupt += OnInterrupt;
}
/// <summary>
/// Private constructor used for deserialization.
/// </summary>
private IpPacket(IpVersion version, byte ihl, byte dscp, ushort totalLength,
ushort identification, IpFlag flags, ushort fragmentOffset,
byte ttl, IpProtocol protocol, ushort checksum, IpAddress source,
IpAddress destination) {
destination.ThrowIfNull("destination");
source.ThrowIfNull("source");
if (ihl > 0x0F)
throw new ArgumentException("The Internet Header Length field must " +
"be in the range from 0 to 15.", nameof(ihl));
if (fragmentOffset > 0x1FFF)
throw new ArgumentException("The Fragment Offset field must be in " +
"the range from 0 to 8191.", nameof(fragmentOffset));
Version = version;
Ihl = ihl;
Dscp = dscp;
TotalLength = totalLength;
Identification = identification;
Flags = flags;
FragmentOffset = fragmentOffset;
TimeToLive = ttl;
Protocol = protocol;
Checksum = checksum;
Source = source;
Destination = destination;
Data = new byte[0];
}
/// <summary>
/// Initializes a new instance of the IpPacket class using the specified
/// values.
/// </summary>
/// <param name="destination">The IPv4 address of the destination
/// host.</param>
/// <param name="source">The IPv4 address of the sending host.</param>
/// <param name="type">The type of the transport protocol encapsulated in
/// the IP packet's data section.</param>
/// <param name="fragmentOffset">The fragment offset of the packet.</param>
/// <param name="data">The transport data to transfer as part of the IP
/// packet.</param>
/// <param name="ihl">The Internet Header Length.</param>
/// <param name="dscp">The Differentiated Services Code Point.</param>
/// <param name="ttl">The time-to-live of the IP packet.</param>
/// <param name="identification">The idenfication used for uniquely identifying
/// fragments of a fragmented IP packet.</param>
/// <param name="flags">The flags set on the IP packet.</param>
/// <exception cref="ArgumentNullException">Thrown if any of the arguments
/// is null.</exception>
public IpPacket(IpAddress destination, IpAddress source,
IpProtocol type, byte ihl, byte dscp, byte ttl, ushort identification,
IpFlag flags, ushort fragmentOffset, byte[] data) {
destination.ThrowIfNull("destination");
source.ThrowIfNull("source");
data.ThrowIfNull("data");
if (ihl > 0x0F)
throw new ArgumentException("The Internet Header Length field must " +
"be in the range from 0 to 15.", nameof(ihl));
if (fragmentOffset > 0x1FFF)
throw new ArgumentException("The Fragment Offset field must be in " +
"the range from 0 to 8191.", nameof(fragmentOffset));
Version = IpVersion.Ipv4;
Ihl = ihl;
Dscp = dscp;
Identification = identification;
Flags = flags;
FragmentOffset = fragmentOffset;
TimeToLive = ttl;
Protocol = type;
Source = source;
Destination = destination;
Data = data;
TotalLength = (ushort) (20 + Data.Length);
Checksum = ComputeChecksum(this);
}
/// <summary>
/// Initializes a new instance of the IpPacket class using the specified
/// values.
/// </summary>
/// <param name="destination">The IPv4 address of the destination
/// host.</param>
/// <param name="source">The IPv4 address of the sending host.</param>
/// <param name="type">The type of the transport protocol encapsulated in
/// the IP packet's data section.</param>
/// <param name="data">The transport data to transfer as part of the IP
/// packet.</param>
/// <exception cref="ArgumentNullException">Thrown if any of the arguments
/// is null.</exception>
public IpPacket(IpAddress destination, IpAddress source,
IpProtocol type, byte[] data) {
destination.ThrowIfNull("destination");
source.ThrowIfNull("source");
data.ThrowIfNull("data");
Destination = destination;
Source = source;
Protocol = type;
Data = data;
TimeToLive = 64;
Ihl = 5;
TotalLength = (ushort) (20 + Data.Length);
Version = IpVersion.Ipv4;
Checksum = ComputeChecksum(this);
}
