Dns Unicode C++ Reference Documentation
CkDnsW
Current Version: 10.1.2
API for managing DNS nameservers to be used by Chilkat, and for doing DNS queries.
Object Creation
// Local variable on the stack CkDnsW obj; // Dynamically allocate/delete CkDnsW *pObj = new CkDnsW(); // ... delete pObj;
Properties
DebugLogFilePath
const wchar_t *debugLogFilePath(void);
void put_DebugLogFilePath(const wchar_t *str);
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
HeartbeatMs
void put_HeartbeatMs(int newVal);
The number of milliseconds between each AbortCheck event callback. The AbortCheck callback allows an application to abort any DNS operation prior to completion. If HeartbeatMs is 0 (the default), no AbortCheck event callbacks will fire.
topLastErrorHtml
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
void put_LastMethodSuccess(bool newVal);
Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.
topMaxWaitMs
void put_MaxWaitMs(int newVal);
The maxiumum number of milliseconds to wait for the answer to a DNS query. A value of 0 is to wait indefinitely (no timeout). It's not a good idea to specify 0 (infinite timeout) or a value less than 1000 (1 second). The default value is 10000 milliseconds.
topNumNameservers
The number of nameservers currently being used by Chilkat for DNS queries in all objects/classes, such as for HTTP, Email, FTP, SSH, etc.
topTlsPref
void put_TlsPref(int newVal);
Specifies the TLS preference. Possible values are:
- 0 = No TLS
- 1 = Prefer TLS if possible.
- 2 = Require TLS
The default value is 0. If TLS is preferred then DNS nameservers with TLS capability will be tried first. If none succeed, then UDP/TCP will be tried. If TLS is required, then only TLS capable nameservers will be tried and all DNS queries will use TLS.
Note: To use TLS, your application needs to first specify nameservers by calling AddNameserver once per nameserver with the supportsTls argument set to true.
topVerboseLogging
void put_VerboseLogging(bool newVal);
If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
topVersion
Methods
AddDefaultNameservers
Adds the default (auto-assigned) nameservers to the collection of nameservers used by Chilkat for DNS queries and domain to IP address lookups.
AddNameserver
Adds a new nameserver to the collection of nameservers used by Chilkat for DNS queries and domain to IP address lookups. The ipAddr specifies the IPv4 address of the nameserver. The supportsTls indicates if the namserver supports DoT (DNS over TLS. DoT uses port 853 for encrypted DNS communication.) If the TlsPreference property is set to 1 or 2, then Chilkat will use TLS nameservers.
GetNameserver
Returns the IP address of the Nth nameserver currently used by Chilkat for DNS queries and domain to IP address lookups. The index specifies the index of the nameserver. The 1st nameserver is at index 0.
Returns true for success, false for failure.
Query
Performs an DNS query for domain and returns the answer in answer. The type of DNS query is specified in recordType and can be A, AAAA, ALIAS, CAA, MX, NS, SOA, TXT. Additional record types can be added as needed.
QueryAsync (1)
Creates an asynchronous task to call the Query method with the arguments provided.
Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.
Note: The application is responsible for deleting (via the C++ delete operator) the object returned by this method.
Returns NULL on failure
topRemoveAllNameservers
Removes all nameservers from the collection of nameservers used by Chilkat. An application can call this method to reset to 0 nameservers before adding new nameservers. If a DNS domain to IP address resolution is needed by Chilkat, then the auto-assigned nameserver IP addresses will be automaticaly restored.
RemoveNameserver
Removes a nameserver from the collection of nameservers used by Chilkat. The ipAddr is the IPv4 address of the nameserver to be removed.
topEvents
To implement an event callback, your application would define and implement a class that inherits from CkBaseProgressW. Your application can implement methods to override some or all of the default/empty method implementations of the CkBaseProgressW base class.
For example:
CkDnsW dns; MyDnsProgressW callbackObj; dns.put_EventCallbackObject(&callbackObj);
MyDnsProgressW example:
#include "CkBaseProgressW.h"
class MyDnsProgressW : public CkBaseProgressW {
public:
MyDnsProgressW();
virtual ~MyDnsProgressW();
void AbortCheck(bool *abort);
void PercentDone(int pctDone, bool *abort);
void ProgressInfo(const wchar_t *name, const wchar_t *value);
void TaskCompleted(CkTaskW &task);
};AbortCheck
Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.
PercentDone
Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).
The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.
The abort output argument provides a means for aborting the operation. Setting it to true will cause the method to abort and return a failed status (or whatever return value indicates failure).
ProgressInfo
A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.
TaskCompleted
Called in the background thread when an asynchronous task completes.