ICMP Module

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The ICMP module 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

IPWorks.Icmp

Remarks

The interface of the class is similar to the interface of TCPClient, only it is much simpler. The class 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 class 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 class 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 class 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 module with short descriptions. Click on the links for further details.

Method List

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

Event List

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

Config Settings

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

AcceptData Property (ICMP Module)

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

Syntax

• Swift
• Objective-C

public var acceptData: Bool {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=acceptData,setter=setAcceptData:) BOOL acceptData;

- (BOOL)acceptData;
- (void)setAcceptData :(BOOL)newAcceptData;

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.

Active Property (ICMP Module)

This property indicates whether the module is active.

Syntax

• Swift
• Objective-C

public var active: Bool {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=active,setter=setActive:) BOOL active;

- (BOOL)active;
- (void)setActive :(BOOL)newActive;

Default Value

False

Remarks

This property indicates whether the class 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 class is active.

DataToSend Property (ICMP Module)

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

Syntax

• Swift
• Objective-C

public var dataToSend: String {  set {...}
}

public var dataToSendB: Data {  set {...}
}

@property (nonatomic,readwrite,assign,getter=dataToSend,setter=setDataToSend:) NSString* dataToSend;

- (NSString*)dataToSend;
- (void)setDataToSend :(NSString*)newDataToSend;

@property (nonatomic,readwrite,assign,getter=dataToSendB,setter=setDataToSendB:) NSData* dataToSendB;

- (NSData*)dataToSendB;
- (void)setDataToSendB :(NSData*)newDataToSend;

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 class 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 .

This property is write-only.

DontRoute Property (ICMP Module)

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

Syntax

• Swift
• Objective-C

public var dontRoute: Bool {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=dontRoute,setter=setDontRoute:) BOOL dontRoute;

- (BOOL)dontRoute;
- (void)setDontRoute :(BOOL)newDontRoute;

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.

LocalHost Property (ICMP Module)

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

Syntax

• Swift
• Objective-C

public var localHost: String {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=localHost,setter=setLocalHost:) NSString* localHost;

- (NSString*)localHost;
- (void)setLocalHost :(NSString*)newLocalHost;

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 class initiate connections (or accept in the case of server classs) only through that interface.

If the class 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 Module)

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

Syntax

• Swift
• Objective-C

public var messageSubType: Int32 {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=messageSubType,setter=setMessageSubType:) int messageSubType;

- (int)messageSubType;
- (void)setMessageSubType :(int)newMessageSubType;

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 Module)

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

Syntax

• Swift
• Objective-C

public var messageType: Int32 {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=messageType,setter=setMessageType:) int messageType;

- (int)messageType;
- (void)setMessageType :(int)newMessageType;

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 Module)

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

Syntax

• Swift
• Objective-C

public var remoteHost: String {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=remoteHost,setter=setRemoteHost:) NSString* remoteHost;

- (NSString*)remoteHost;
- (void)setRemoteHost :(NSString*)newRemoteHost;

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 class 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 class .

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

Timeout Property (ICMP Module)

A timeout for the module.

Syntax

• Swift
• Objective-C

public var timeout: Int32 {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=timeout,setter=setTimeout:) int timeout;

- (int)timeout;
- (void)setTimeout :(int)newTimeout;

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 class will automatically retry each operation that would otherwise result in a 'WOULDBLOCK' error for a maximum of Timeout seconds.

The class 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 class .

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).

TimeToLive Property (ICMP Module)

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

Syntax

• Swift
• Objective-C

public var timeToLive: Int32 {
  get {...}
  set {...}
}

@property (nonatomic,readwrite,assign,getter=timeToLive,setter=setTimeToLive:) int timeToLive;

- (int)timeToLive;
- (void)setTimeToLive :(int)newTimeToLive;

Default Value

0

Remarks

This method contains the time-to-live (TTL) value for the ICMP packets sent by the class. 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.

Activate Method (ICMP Module)

This method enables sending and receiving of data.

Syntax

• Swift
• Objective-C

public func activate() throws -> Void

- (void)activate;

Remarks

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

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

Config Method (ICMP Module)

Sets or retrieves a configuration setting.

Syntax

• Swift
• Objective-C

public func config(configurationString: String) throws -> String

- (NSString*)config:(NSString*)configurationString;

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, 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 Module)

This method disables sending and receiving of data.

Syntax

• Swift
• Objective-C

public func deactivate() throws -> Void

- (void)deactivate;

Remarks

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

DoEvents Method (ICMP Module)

Processes events from the internal message queue.

Syntax

• Swift
• Objective-C

public func doEvents() throws -> Void

- (void)doEvents;

Remarks

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

PauseData Method (ICMP Module)

This method pauses data reception.

Syntax

• Swift
• Objective-C

public func pauseData() throws -> Void

- (void)pauseData;

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 Module)

This method reenables data reception after a call to PauseData .

Syntax

• Swift
• Objective-C

public func processData() throws -> Void

- (void)processData;

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 Module)

Reset the component.

Syntax

• Swift
• Objective-C

public func reset() throws -> Void

- (void)reset;

Remarks

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

ResolveRemoteHost Method (ICMP Module)

Resolves the hostname in RemoteHost to an IP address.

Syntax

• Swift
• Objective-C

public func resolveRemoteHost() throws -> Void

- (void)resolveRemoteHost;

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 class will resolve the hostname automatically when necessary. If DelayHostResolution is this method may be called to manually resolve RemoteHost if desired.

Send Method (ICMP Module)

This method sends data to the remote host.

Syntax

• Swift
• Objective-C

public func send(text: Data) throws -> Void

- (void)send:(NSData*)text;

Remarks

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

SendBytes Method (ICMP Module)

This method sends data to the remote host.

Syntax

• Swift
• Objective-C

public func sendBytes(data: Data) throws -> Void

- (void)sendBytes:(NSData*)data;

Remarks

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

SendText Method (ICMP Module)

This method sends data to the remote host.

Syntax

• Swift
• Objective-C

public func sendText(text: String) throws -> Void

- (void)sendText:(NSString*)text;

Remarks

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

DataIn Event (ICMP Module)

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

Syntax

• Swift
• Objective-C

func onDataIn(messageType: Int32, messageSubType: Int32, messageData: Data, checksum: Int32, sourceAddress: String)

- (void)onDataIn:(int)messageType :(int)messageSubType :(NSData*)messageData :(int)checksum :(NSString*)sourceAddress;

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 Module)

Fired when information is available about errors during data delivery.

Syntax

• Swift
• Objective-C

func onError(errorCode: Int32, description: String)

- (void)onError:(int)errorCode :(NSString*)description;

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class .

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 Module)

Fired when the component is ready to send data.

Syntax

• Swift
• Objective-C

func onReadyToSend()

- (void)onReadyToSend;

Remarks

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

Config Settings (ICMP Module)

ICMP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (ICMP Module)

ICMP Errors

SSL Errors

TCP/IP Errors