ICMP Component

Properties   Methods   Events   Config Settings   Errors  

The ICMP component is used to facilitate ICMP communications. It can act both as a client and a server and can communicate with any number of hosts simultaneously. It also can generate and receive broadcast packets.

Syntax

nsoftware.IPWorks.Icmp

Remarks

The interface of the component is similar to the interface of TCPClient, only it is much simpler. The component is activated/deactivated by using the Active property. This property enables or disables the sending or receiving of data. Data can be sent in the same way as TCPClient, using the Send method and Text parameter or the DataToSend property. The destination is specified using the RemoteHost property. The component automatically creates an ICMP header containing MessageType, MessageSubType, and a checksum for the message.

If the UseConnection configuration setting is set to True, then a local association is created with the remote host. Otherwise, the component can receive datagrams (packets) from any host and can send datagrams to any host. Packets can be broadcast on the local net by setting the destination to 255.255.255.255.

Inbound data is received through the DataIn event.

The operation of the component is almost completely asynchronous. All the calls, except the ones that deal with domain name resolution, operate through Windows messages (no blocking calls). The gain in performance is considerable when compared with using blocking calls.

Property List

The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the component with short descriptions. Click on the links for further details.

AcceptData Property (ICMP Component)

This property enables or disables data reception (the DataIn event).

Syntax

• C#
• VB.NET

public bool AcceptData { get; set; }

Public Property AcceptData As Boolean

Default Value

True

Remarks

This property enables or disables data reception (the DataIn event). Setting this property to False, temporarily disables data reception (and the DataIn event). Setting this property to True, reenables data reception.

Note: It is recommended to use the PauseData or ProcessData method instead of setting this property.

This property is not available at design time.

Active Property (ICMP Component)

This property indicates whether the component is active.

Syntax

• C#
• VB.NET

public bool Active { get; set; }

Public Property Active As Boolean

Default Value

False

Remarks

This property indicates whether the component is currently active and can send or receive data.

If the UseConnection configuration setting is set to True, then a local association (connection) to the remote host also is created.

Note: Use the Activate or Deactivate method to control whether the component is active.

This property is not available at design time.

DataToSend Property (ICMP Component)

This write-only property includes a string of data to be sent to the remote host.

Syntax

• C#
• VB.NET

public string DataToSend { set; }
public byte[] DataToSendB { set; }

Public WriteOnly Property DataToSend As String
Public WriteOnly Property DataToSendB As Byte()

Default Value

""

Remarks

This property is write-only and contains a string of data to be sent to the remote host. Assigning a string to this property makes the component send the string to the remote host. The Send method provides similar functionality.

The Transmission Control Protocol (TCP)/IP subsystem attempts to send the string assigned to this property as a complete message. If socket buffers are full, or if the message cannot be delivered for any other reason, an error is fired, and no portion of the message is sent. This is different from TCP in which case portions of the messages can be sent. ICMP sends either a complete message or nothing at all.

If you are sending data to the remote host faster than it can process it, or faster than the network's bandwidth allows, the outgoing queue might fill up. When this happens, DataToSend fails with exception 10035: "[10035] Operation would block" (WSAEWOULDBLOCK). You can check this error, and then try to send the data again. .

This property is write-only and not available at design time.

DontRoute Property (ICMP Component)

If this property is set to True, it forces the socket to send data directly to the interface (no routing).

Syntax

• C#
• VB.NET

public bool DontRoute { get; set; }

Public Property DontRoute As Boolean

Default Value

False

Remarks

If this property is set to True, it forces the socket to send data directly to the interface (no routing). Normally, IP sockets send packets of data through routers and gateways until they reach the final destination. If this property is set to True, then data will be delivered on the local subnet only.

This property is not available at design time.

LocalHost Property (ICMP Component)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

• C#
• VB.NET

public string LocalHost { get; set; }

Public Property LocalHost As String

Default Value

""

Remarks

The LocalHost property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the component initiate connections (or accept in the case of server components) only through that interface.

If the component is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).

NOTE: LocalHost is not persistent. You must always set it in code, and never in the property window.

MessageSubType Property (ICMP Component)

This property is the subtype of the ICMP message (part of the ICMP header).

Syntax

• C#
• VB.NET

public int MessageSubType { get; set; }

Public Property MessageSubType As Integer

Default Value

0

Remarks

This property contains the subtype of the ICMP message (part of the ICMP header). The ICMP message subtype (also referred to as "code") is a byte value representing the message subclass. Its meaning is associated with the MessageType.

Types and subtypes of ICMP messages are defined in the various internet RFCs and other documentation associated with Transmission Control Protocol (TCP)/IP.

MessageType Property (ICMP Component)

This property includes the type of the ICMP message (part of the ICMP header).

Syntax

• C#
• VB.NET

public int MessageType { get; set; }

Public Property MessageType As Integer

Default Value

0

Remarks

This property contains the type of the ICMP message (part of the ICMP header). The ICMP message type is a byte value representing the message class. The message type defines the structure and meaning of the message data assigned to DataToSend.

Types for ICMP messages are defined in the various internet RFCs and other documentation associated with Transmission Control Protocol (TCP/IP). The following are a few examples of ICMP message types:

RemoteHost Property (ICMP Component)

This property includes the address of the RemoteHost. Domain names are resolved to IP addresses.

Syntax

• C#
• VB.NET

public string RemoteHost { get; set; }

Public Property RemoteHost As String

Default Value

""

Remarks

This property specifies the IP address (IP number in dotted internet format) or the domain name of the remote host.

If this property is set to 255.255.255.255, the component broadcasts data on the local subnet.

If this property is set to a domain name, a DNS request is initiated. Upon successful termination of the request, the property is set to the corresponding address. If the search is not successful, the component throws an exception.

If UseConnection is True, this property must be set before the component is activated (Active is set to True).

Timeout Property (ICMP Component)

A timeout for the component.

Syntax

• C#
• VB.NET

public int Timeout { get; set; }

Public Property Timeout As Integer

Default Value

0

Remarks

If the Timeout property is set to 0, all operations return immediately, potentially failing with an 'WOULDBLOCK' error if data can't be sent or received immediately.

If Timeout is set to a positive value, the component will automatically retry each operation that would otherwise result in a 'WOULDBLOCK' error for a maximum of Timeout seconds.

The component will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not "freeze" and remains responsive.

If Timeout expires, and the operation is not yet complete, the component throws an exception.

Please note that by default, all timeouts are inactivity timeouts, i.e. the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for the Timeout property is 0 (asynchronous operation).

Note: when a communication component behaves asynchronously in .NET, some events can fire from the background threads used to process socket IO. This can cause problems in GUI applications where there is logic inside an asynchronous event that interacts with the GUI. In .NET, most GUI controls will not allow themselves to be accessed from any thread other than the one that created them due to potential deadlocking issues. To ensure the user can do this, the .NET GUI API supplies a BeginInvoke method that can be used to access GUI controls from other threads, such as the ones that fire events. You can also set the InvokeThrough property of the communication component to any control on the GUI form to direct the component to forward all events through that control.

TimeToLive Property (ICMP Component)

This property includes the time-to-live (TTL) value for the ICMP packets sent by the component.

Syntax

• C#
• VB.NET

public int TimeToLive { get; set; }

Public Property TimeToLive As Integer

Default Value

0

Remarks

This method contains the time-to-live (TTL) value for the ICMP packets sent by the component. The TTL field of the ICMP packet is a counter limiting the lifetime of a packet.

Each router (or other module) that handles a packet decrements the TTL field by one or more if it holds the packet for more than one second. Thus, the TTL value is effectively a hop count limit on how far a datagram can propagate through the internet. When the TTL value is reduced to zero (or less), the packet is discarded.

If the value of the property is set to zero, then the default TTL value of the underlying Transmission Control Protocol (TCP)/IP subsystem will be used.

This property is not available at design time.

Activate Method (ICMP Component)

This method enables sending and receiving of data.

Syntax

• C#
• VB.NET

public void Activate();

Async Version
public async Task Activate();
public async Task Activate(CancellationToken cancellationToken);

Public Sub Activate()

Async Version
Public Sub Activate() As Task
Public Sub Activate(cancellationToken As CancellationToken) As Task

Remarks

This method enables sending and receiving of data. When called, the component will create a communication endpoint (socket) that can be used for sending and receiving ICMP messages. This method must be called before using the component to send and receive data.

If the UseConnection configuration setting is set to true, then a local association (connection) to the remote host also is created.

Config Method (ICMP Component)

Sets or retrieves a configuration setting.

Syntax

• C#
• VB.NET

public string Config(string configurationString);

Async Version
public async Task<string> Config(string configurationString);
public async Task<string> Config(string configurationString, CancellationToken cancellationToken);

Public Function Config(ByVal ConfigurationString As String) As String

Async Version
Public Function Config(ByVal ConfigurationString As String) As Task(Of String)
Public Function Config(ByVal ConfigurationString As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Deactivate Method (ICMP Component)

This method disables sending and receiving of data.

Syntax

• C#
• VB.NET

public void Deactivate();

Async Version
public async Task Deactivate();
public async Task Deactivate(CancellationToken cancellationToken);

Public Sub Deactivate()

Async Version
Public Sub Deactivate() As Task
Public Sub Deactivate(cancellationToken As CancellationToken) As Task

Remarks

This method disables sending and receiving of data. When called, the component will destroy the existing socket and disable data communications.

DoEvents Method (ICMP Component)

Processes events from the internal message queue.

Syntax

• C#
• VB.NET

public void DoEvents();

Async Version
public async Task DoEvents();
public async Task DoEvents(CancellationToken cancellationToken);

Public Sub DoEvents()

Async Version
Public Sub DoEvents() As Task
Public Sub DoEvents(cancellationToken As CancellationToken) As Task

Remarks

When DoEvents is called, the component processes any available events. If no events are available, it waits for a preset period of time, and then returns.

PauseData Method (ICMP Component)

This method pauses data reception.

Syntax

• C#
• VB.NET

public void PauseData();

Async Version
public async Task PauseData();
public async Task PauseData(CancellationToken cancellationToken);

Public Sub PauseData()

Async Version
Public Sub PauseData() As Task
Public Sub PauseData(cancellationToken As CancellationToken) As Task

Remarks

This method pauses data reception when called. While data reception is paused, the DataIn event will not fire. Call ProcessData to reenable data reception.

ProcessData Method (ICMP Component)

This method reenables data reception after a call to PauseData

Syntax

• C#
• VB.NET

public void ProcessData();

Async Version
public async Task ProcessData();
public async Task ProcessData(CancellationToken cancellationToken);

Public Sub ProcessData()

Async Version
Public Sub ProcessData() As Task
Public Sub ProcessData(cancellationToken As CancellationToken) As Task

Remarks

This method reenables data reception after a previous call to PauseData. When PauseData is called, the DataIn event will not fire. To reenable data reception and allow DataIn to fire, call this method.

Note: This method is used only after previously calling PauseData. It does not need to be called to process incoming data by default.

Reset Method (ICMP Component)

Reset the component.

Syntax

• C#
• VB.NET

public void Reset();

Async Version
public async Task Reset();
public async Task Reset(CancellationToken cancellationToken);

Public Sub Reset()

Async Version
Public Sub Reset() As Task
Public Sub Reset(cancellationToken As CancellationToken) As Task

Remarks

This method will reset the component's properties to their default values.

ResolveRemoteHost Method (ICMP Component)

Resolves the hostname in RemoteHost to an IP address.

Syntax

• C#
• VB.NET

public void ResolveRemoteHost();

Async Version
public async Task ResolveRemoteHost();
public async Task ResolveRemoteHost(CancellationToken cancellationToken);

Public Sub ResolveRemoteHost()

Async Version
Public Sub ResolveRemoteHost() As Task
Public Sub ResolveRemoteHost(cancellationToken As CancellationToken) As Task

Remarks

This method resolves the hostname specified by RemoteHost to an IP address. The resolved value is available in the RemoteHost property after this method returns.

In most cases calling this method is not necessary, the component will resolve the hostname automatically when necessary. If DelayHostResolution is true this method may be called to manually resolve RemoteHost if desired.

Send Method (ICMP Component)

This method sends data to the remote host.

Syntax

• C#
• VB.NET

public void Send(byte[] text);

Async Version
public async Task Send(byte[] text);
public async Task Send(byte[] text, CancellationToken cancellationToken);

Public Sub Send(ByVal Text As String)

Async Version
Public Sub Send(ByVal Text As String) As Task
Public Sub Send(ByVal Text As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends data to the remote host. Calling this method is equivalent to setting the DataToSend property to Text.

SendBytes Method (ICMP Component)

This method sends data to the remote host.

Syntax

• C#
• VB.NET

public void SendBytes(byte[] data);

Async Version
public async Task SendBytes(byte[] data);
public async Task SendBytes(byte[] data, CancellationToken cancellationToken);

Public Sub SendBytes(ByVal Data As String)

Async Version
Public Sub SendBytes(ByVal Data As String) As Task
Public Sub SendBytes(ByVal Data As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends data to the remote host. Calling this method is equivalent to calling the SendBytes/SendText method.

SendText Method (ICMP Component)

This method sends data to the remote host.

Syntax

• C#
• VB.NET

public void SendText(string text);

Async Version
public async Task SendText(string text);
public async Task SendText(string text, CancellationToken cancellationToken);

Public Sub SendText(ByVal Text As String)

Async Version
Public Sub SendText(ByVal Text As String) As Task
Public Sub SendText(ByVal Text As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends data to the remote host. Calling this method is equivalent to calling the SendBytes/SendText method.

DataIn Event (ICMP Component)

This event is fired when a new ICMP messages come in.

Syntax

• C#
• VB.NET

public event OnDataInHandler OnDataIn;

public delegate void OnDataInHandler(object sender, IcmpDataInEventArgs e);

public class IcmpDataInEventArgs : EventArgs {
  public int MessageType { get; }
  public int MessageSubType { get; }
  public string MessageData { get; }
  public byte[] MessageDataB { get; }
  public int Checksum { get; }
  public string SourceAddress { get; }
}

Public Event OnDataIn As OnDataInHandler

Public Delegate Sub OnDataInHandler(sender As Object, e As IcmpDataInEventArgs)

Public Class IcmpDataInEventArgs Inherits EventArgs
  Public ReadOnly Property MessageType As Integer
  Public ReadOnly Property MessageSubType As Integer
  Public ReadOnly Property MessageData As String
  Public ReadOnly Property MessageDataB As Byte()
  Public ReadOnly Property Checksum As Integer
  Public ReadOnly Property SourceAddress As String
End Class

Remarks

The MessageType parameter shows the type of the ICMP messages and the MessageSubType parameter shows its subtype.

The MessageData parameter contains the message data.

The Checksum parameter is True or False depending on the ICMP checksum validation on the message.

Note: Events are not re-entrant. Performing time-consuming operations within this event will prevent it from firing again in a timely manner and may affect overall performance.

Error Event (ICMP Component)

Fired when information is available about errors during data delivery.

Syntax

• C#
• VB.NET

public event OnErrorHandler OnError;

public delegate void OnErrorHandler(object sender, IcmpErrorEventArgs e);

public class IcmpErrorEventArgs : EventArgs {
  public int ErrorCode { get; }
  public string Description { get; }
}

Public Event OnError As OnErrorHandler

Public Delegate Sub OnErrorHandler(sender As Object, e As IcmpErrorEventArgs)

Public Class IcmpErrorEventArgs Inherits EventArgs
  Public ReadOnly Property ErrorCode As Integer
  Public ReadOnly Property Description As String
End Class

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

ReadyToSend Event (ICMP Component)

Fired when the component is ready to send data.

Syntax

• C#
• VB.NET

public event OnReadyToSendHandler OnReadyToSend;

public delegate void OnReadyToSendHandler(object sender, IcmpReadyToSendEventArgs e);

public class IcmpReadyToSendEventArgs : EventArgs {
}

Public Event OnReadyToSend As OnReadyToSendHandler

Public Delegate Sub OnReadyToSendHandler(sender As Object, e As IcmpReadyToSendEventArgs)

Public Class IcmpReadyToSendEventArgs Inherits EventArgs
End Class

Remarks

The ReadyToSend event indicates that the underlying TCP/IP subsystem is ready to accept data after a failed DataToSend.

Config Settings (ICMP Component)

ICMP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (ICMP Component)

ICMP Errors

SSL Errors

TCP/IP Errors