ICMP Class

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The ICMP class 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.

Class Name

IPWorks_ICMP

Procedural Interface

 ipworks_icmp_open();
 ipworks_icmp_close($res);
 ipworks_icmp_register_callback($res, $id, $function);
 ipworks_icmp_get_last_error($res);
 ipworks_icmp_get_last_error_code($res);
 ipworks_icmp_set($res, $id, $index, $value);
 ipworks_icmp_get($res, $id, $index);
 ipworks_icmp_do_activate($res);
 ipworks_icmp_do_config($res, $configurationstring);
 ipworks_icmp_do_deactivate($res);
 ipworks_icmp_do_doevents($res);
 ipworks_icmp_do_pausedata($res);
 ipworks_icmp_do_processdata($res);
 ipworks_icmp_do_reset($res);
 ipworks_icmp_do_resolveremotehost($res);
 ipworks_icmp_do_send($res, $text);
 ipworks_icmp_do_sendbytes($res, $data);
 ipworks_icmp_do_sendtext($res, $text);

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. 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

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

Method List

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

Event List

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

Config Settings

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

AcceptData Property (IPWorks_ICMP Class)

This property indicates whether data reception is currently enabled.

Object Oriented Interface

public function getAcceptData();

Procedural Interface

ipworks_icmp_get($res, 1 );

Default Value

true

Remarks

This property indicates whether data reception is currently enabled. When false, data reception is disabled and the DataIn event will not fire. Use the PauseData and ProcessData methods to pause and resume data reception.

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

Data Type

Boolean

Active Property (IPWorks_ICMP Class)

This property indicates whether the class is active.

Object Oriented Interface

public function getActive();

Procedural Interface

ipworks_icmp_get($res, 2 );

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. Use the Activate and Deactivate methods to control whether the class is active.

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

Data Type

Boolean

DontRoute Property (IPWorks_ICMP Class)

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

Object Oriented Interface

public function getDontRoute();
public function setDontRoute($value);

Procedural Interface

ipworks_icmp_get($res, 3 );
ipworks_icmp_set($res, 3, $value );

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.

Data Type

Boolean

LocalHost Property (IPWorks_ICMP Class)

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

Object Oriented Interface

public function getLocalHost();
public function setLocalHost($value);

Procedural Interface

ipworks_icmp_get($res, 4 );
ipworks_icmp_set($res, 4, $value );

Default Value

''

Remarks

This 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 multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

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 multihomed 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.

Data Type

String

MessageSubType Property (IPWorks_ICMP Class)

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

Object Oriented Interface

public function getMessageSubType();
public function setMessageSubType($value);

Procedural Interface

ipworks_icmp_get($res, 5 );
ipworks_icmp_set($res, 5, $value );

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.

Data Type

Integer

MessageType Property (IPWorks_ICMP Class)

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

Object Oriented Interface

public function getMessageType();
public function setMessageType($value);

Procedural Interface

ipworks_icmp_get($res, 6 );
ipworks_icmp_set($res, 6, $value );

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 Text parameter of the Send method.

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:

Data Type

Integer

RemoteHost Property (IPWorks_ICMP Class)

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

Object Oriented Interface

public function getRemoteHost();
public function setRemoteHost($value);

Procedural Interface

ipworks_icmp_get($res, 7 );
ipworks_icmp_set($res, 7, $value );

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 fails with an error.

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

Data Type

String

Timeout Property (IPWorks_ICMP Class)

This property specifies the timeout for the class.

Object Oriented Interface

public function getTimeout();
public function setTimeout($value);

Procedural Interface

ipworks_icmp_get($res, 8 );
ipworks_icmp_set($res, 8, $value );

Default Value

0

Remarks

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

If Timeout is set to a positive value, the class will automatically retry each operation that otherwise would 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 fails with an error.

Note: By default, all timeouts are inactivity timeouts, that is, 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).

Data Type

Integer

TimeToLive Property (IPWorks_ICMP Class)

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

Object Oriented Interface

public function getTimeToLive();
public function setTimeToLive($value);

Procedural Interface

ipworks_icmp_get($res, 9 );
ipworks_icmp_set($res, 9, $value );

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.

This property is not available at design time.

Data Type

Integer

Activate Method (IPWorks_ICMP Class)

This method enables sending and receiving of data.

Object Oriented Interface

public function doActivate();

Procedural Interface

ipworks_icmp_do_activate($res);

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 true, then a local association (connection) to the remote host also is created.

Config Method (IPWorks_ICMP Class)

Sets or retrieves a configuration setting.

Object Oriented Interface

public function doConfig($configurationstring);

Procedural Interface

ipworks_icmp_do_config($res, $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 (IPWorks_ICMP Class)

This method disables sending and receiving of data.

Object Oriented Interface

public function doDeactivate();

Procedural Interface

ipworks_icmp_do_deactivate($res);

Remarks

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

DoEvents Method (IPWorks_ICMP Class)

This method processes events from the internal message queue.

Object Oriented Interface

public function doEvents();

Procedural Interface

ipworks_icmp_do_doevents($res);

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 (IPWorks_ICMP Class)

This method pauses data reception.

Object Oriented Interface

public function doPauseData();

Procedural Interface

ipworks_icmp_do_pausedata($res);

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 (IPWorks_ICMP Class)

This method reenables data reception after a call to PauseData .

Object Oriented Interface

public function doProcessData();

Procedural Interface

ipworks_icmp_do_processdata($res);

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 (IPWorks_ICMP Class)

This method will reset the class.

Object Oriented Interface

public function doReset();

Procedural Interface

ipworks_icmp_do_reset($res);

Remarks

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

ResolveRemoteHost Method (IPWorks_ICMP Class)

This method resolves the hostname in RemoteHost to an IP address.

Object Oriented Interface

public function doResolveRemoteHost();

Procedural Interface

ipworks_icmp_do_resolveremotehost($res);

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 needed. If DelayHostResolution is true, this method may be called to manually resolve RemoteHost, if desired.

Send Method (IPWorks_ICMP Class)

This method sends data to the remote host.

Object Oriented Interface

public function doSend($text);

Procedural Interface

ipworks_icmp_do_send($res, $text);

Remarks

This method sends data to the remote host.

SendBytes Method (IPWorks_ICMP Class)

This method sends data to the remote host.

Object Oriented Interface

public function doSendBytes($data);

Procedural Interface

ipworks_icmp_do_sendbytes($res, $data);

Remarks

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

SendText Method (IPWorks_ICMP Class)

This method sends data to the remote host.

Object Oriented Interface

public function doSendText($text);

Procedural Interface

ipworks_icmp_do_sendtext($res, $text);

Remarks

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

DataIn Event (IPWorks_ICMP Class)

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

Object Oriented Interface

public function fireDataIn($param);

Procedural Interface

ipworks_icmp_register_callback($res, 1, array($this, 'fireDataIn'));

Parameter List

 'messagetype'
 'messagesubtype'
 'messagedata'
 'checksum'
 '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 (IPWorks_ICMP Class)

Fired when information is available about errors during data delivery.

Object Oriented Interface

public function fireError($param);

Procedural Interface

ipworks_icmp_register_callback($res, 2, array($this, 'fireError'));

Parameter List

 'errorcode'
 'description'

Remarks

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

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 (IPWorks_ICMP Class)

This event is fired when the class is ready to send data.

Object Oriented Interface

public function fireReadyToSend($param);

Procedural Interface

ipworks_icmp_register_callback($res, 3, array($this, 'fireReadyToSend'));

Parameter List

Remarks

The ReadyToSend event indicates that the underlying Transmission Control Protocol (TCP)/IP subsystem is ready to accept data after a failed Send.

Config Settings (ICMP Class)

The class accepts one or more of the following configuration settings. Configuration 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.

ICMP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (ICMP Class)

ICMP Errors

SSL Errors

TCP/IP Errors