TraceRoute Component

Properties   Methods   Events   Config Settings   Errors  

The TraceRoute component allows you to trace the path IP packets take on the Internet.

Syntax

TipwTraceRoute

Remarks

The component implements a standard IP Traceroute as defined in RFC 1393.

To use the component, simply call the TraceTo method and set the Host parameter to the domain name or IP address of the host you want to trace the path to. This is identical to setting the RemoteHost property to the domain name or IP address. The component will start sending probe packets towards the host, and as it receives replies it will fire Hop events giving information about the route. The same information is also provided in the Hops properties.

The ResolveNames property enables or disables DNS resolution of IP addresses received during the trace. If set to False only IP addresses are provided. If set to True the component will attempt to resolve the names of the hosts in the route. This may considerably increase the time it takes to complete the trace.

The HopTimeout property determines the maximum waiting time for a response in each hop of the trace, while the Timeout property defines the maximum waiting time for the whole trace. The HopLimit property specifies the maximum number of hops allowed for a trace.

Property List

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

HopLimit Property (TraceRoute Component)

The maximum number of hops to allow for a trace.

Syntax

property HopLimit: Integer read get_HopLimit write set_HopLimit;

Default Value

64

Remarks

This property is used to limit lengthy traces. A value of 0 indicates an unbounded trace.

Note: if the value of Timeout is 0, an unbounded trace may cause a call to TraceTo to block indefinitely. To cancel such a route trace, call Interrupt.

Hops Property (TraceRoute Component)

A collection of hops to the RemoteHost .

Syntax

property Hops: TipwTraceHopList read get_Hops;

Remarks

This property shows the hops as the trace progresses towards the final destination (RemoteHost). Each hop is defined by a TraceHop type.

This property is read-only.

Please refer to the TraceHop type for a complete list of fields.

HopTimeout Property (TraceRoute Component)

Maximum amount of time to wait for an individual hop to complete.

Syntax

property HopTimeout: Integer read get_HopTimeout write set_HopTimeout;

Default Value

10

Remarks

The time value is in seconds. If 0, HopTimeout will be ignored, and only the Timeout for the whole trace will be taken into account.

Idle Property (TraceRoute Component)

The current status of the component.

Syntax

property Idle: Boolean read get_Idle;

Default Value

true

Remarks

Idle will be False if the component is currently busy (communicating and/or waiting for an answer), and True at all other times.

This property is read-only.

LocalHost Property (TraceRoute Component)

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

Syntax

property LocalHost: String read get_LocalHost write set_LocalHost;

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.

RemoteHost Property (TraceRoute Component)

The address of a host to trace to.

Syntax

property RemoteHost: String read get_RemoteHost write set_RemoteHost;

Default Value

''

Remarks

Traces are initiated by setting RemoteHost to the name or address of the host to trace to.

This property must contain a valid Internet domain name or address or an error will be returned.

To interrupt a trace in progress, set RemoteHost to empty string.

Example (Perform a TraceRoute)

TraceRouteControl.TraceTo("myHost") is equivalent to TraceRouteControl.RemoteHost = "myHost"

ResolveNames Property (TraceRoute Component)

Determines whether the component resolves the host name for each host during the trace.

Syntax

property ResolveNames: Boolean read get_ResolveNames write set_ResolveNames;

Default Value

false

Remarks

This property determines whether the component resolves the name of host at each "hop" during the trace. The default value is "False". Please note that the trace takes longer due to name resolution if this property is set to "True".

Timeout Property (TraceRoute Component)

A timeout for the component.

Syntax

property Timeout: Integer read get_Timeout write set_Timeout;

Default Value

60

Remarks

If the Timeout property is set to 0, all operations will run uninterrupted until successful completion or an error condition is encountered.

If Timeout is set to a positive value, the component will wait for the operation to complete before returning control.

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 raises 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 60 seconds.

Config Method (TraceRoute Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): 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.

DoEvents Method (TraceRoute Component)

Processes events from the internal message queue.

Syntax

procedure DoEvents();

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.

Interrupt Method (TraceRoute Component)

Interrupt the current method.

Syntax

procedure Interrupt();

Remarks

If there is no method in progress, Interrupt simply returns, doing nothing.

Reset Method (TraceRoute Component)

Reset the component.

Syntax

procedure Reset();

Remarks

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

ResolveRemoteHost Method (TraceRoute Component)

Resolves the hostname in RemoteHost to an IP address.

Syntax

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

TraceTo Method (TraceRoute Component)

Trace the route to a host.

Syntax

procedure TraceTo(Host: String);

Remarks

Traces are initiated by calling TraceTo, with the Host argument set to the name or address of the destination host to trace to. Host must contain a valid Internet domain name or address, or the component raises an exception. To interrupt a trace in progress, set RemoteHost to empty string. Calling this method is equivalent to setting the RemoteHost property to Host.

Example (Perform a TraceRoute)

TraceRouteControl.TraceTo("myHost") is equivalent to TraceRouteControl.RemoteHost = "myHost"

Error Event (TraceRoute Component)

Fired when information is available about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

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

Hop Event (TraceRoute Component)

Fired for each hop in the trace to the RemoteHost .

Syntax

type THopEvent = procedure (
  Sender: TObject;
  HopNumber: Integer;
  const HostAddress: String;
  Duration: Integer
) of Object;

property OnHop: THopEvent read FOnHop write FOnHop;

Remarks

This event provides access to the information for each hop in the trace. The HopNumber parameter denotes which hop the trace is at. The HostAddress parameter is the IP address of the host for the hop identified by HopNumber. The Duration parameter shows the amount of time taken by the hop.

HopResolved Event (TraceRoute Component)

Fired when the name of a hop address is found.

Syntax

type THopResolvedEvent = procedure (
  Sender: TObject;
  HopNumber: Integer;
  StatusCode: Integer;
  const HopHostName: String
) of Object;

property OnHopResolved: THopResolvedEvent read FOnHopResolved write FOnHopResolved;

Remarks

The StatusCode contains 0 if the address is resolved successfully, or an error code, in which case, HopHostName contains a textual description of the error.

Host name resolution is disabled by default. Set ResolveNames to True to enable it.

TraceHop Type

A hop in the route to the destination.

Remarks

This type describes a hop which exists in the route to the destination specified by the RemoteHost property. This type contains fields denoting the HostAddress, HostName, Time, ErrorCode and ErrorDescription.

Fields

Constructors

constructor Create();

Config Settings (TraceRoute Component)

The component 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 component, access to these internal properties is provided through the Config method.

TraceRoute Config Settings

ICMP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (TraceRoute Component)

TraceRoute Errors

	131   Request queue is full.
	132   Message for unknown request.
	134   Invalid address string.
	159   Invalid hop index (out of range).
	301   Timeout.
	17302   Hop timed out.
	17312   Busy performing current trace.

The component may also return one of the following error codes, which are inherited from other components.

ICMP Errors

	104   The component is already Active.
	107   Cannot change the LocalHost at this time. A connection is in progress.
	109   The component must be Active for this operation.
	112   Cannot change MaxMessageSize while ICMP is Active.
	114   Cannot change RemoteHost when UseConnection is set and the component is Active.
	117   Cannot change UseConnection while the component is Active.
	118   The message cannot be longer than MaxMessageSize.
	119   The message is too short.
	120   Cannot create ICMP handle.

SSL Errors

	270   Cannot load specified security library.
	271   Cannot open certificate store.
	272   Cannot find specified certificate.
	273   Cannot acquire security credentials.
	274   Cannot find certificate chain.
	275   Cannot verify certificate chain.
	276   Error during handshake.
	280   Error verifying certificate.
	281   Could not find client certificate.
	282   Could not find server certificate.
	283   Error encrypting data.
	284   Error decrypting data.

TCP/IP Errors

	10004   [10004] Interrupted system call.
	10009   [10009] Bad file number.
	10013   [10013] Access denied.
	10014   [10014] Bad address.
	10022   [10022] Invalid argument.
	10024   [10024] Too many open files.
	10035   [10035] Operation would block.
	10036   [10036] Operation now in progress.
	10037   [10037] Operation already in progress.
	10038   [10038] Socket operation on non-socket.
	10039   [10039] Destination address required.
	10040   [10040] Message too long.
	10041   [10041] Protocol wrong type for socket.
	10042   [10042] Bad protocol option.
	10043   [10043] Protocol not supported.
	10044   [10044] Socket type not supported.
	10045   [10045] Operation not supported on socket.
	10046   [10046] Protocol family not supported.
	10047   [10047] Address family not supported by protocol family.
	10048   [10048] Address already in use.
	10049   [10049] Can't assign requested address.
	10050   [10050] Network is down.
	10051   [10051] Network is unreachable.
	10052   [10052] Net dropped connection or reset.
	10053   [10053] Software caused connection abort.
	10054   [10054] Connection reset by peer.
	10055   [10055] No buffer space available.
	10056   [10056] Socket is already connected.
	10057   [10057] Socket is not connected.
	10058   [10058] Can't send after socket shutdown.
	10059   [10059] Too many references, can't splice.
	10060   [10060] Connection timed out.
	10061   [10061] Connection refused.
	10062   [10062] Too many levels of symbolic links.
	10063   [10063] File name too long.
	10064   [10064] Host is down.
	10065   [10065] No route to host.
	10066   [10066] Directory not empty
	10067   [10067] Too many processes.
	10068   [10068] Too many users.
	10069   [10069] Disc Quota Exceeded.
	10070   [10070] Stale NFS file handle.
	10071   [10071] Too many levels of remote in path.
	10091   [10091] Network subsystem is unavailable.
	10092   [10092] WINSOCK DLL Version out of range.
	10093   [10093] Winsock not loaded yet.
	11001   [11001] Host not found.
	11002   [11002] Non-authoritative 'Host not found' (try again or check DNS setup).
	11003   [11003] Non-recoverable errors: FORMERR, REFUSED, NOTIMP.
	11004   [11004] Valid name, no data record (check DNS setup).