Dns Objective-C Reference Documentation
CkoDns
Current Version: 11.1.0
API for managing DNS nameservers to be used by Chilkat, and for doing DNS queries.
Object Creation
CkoDns *obj = [[CkoDns alloc] init];
Properties
DebugLogFilePath
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
The interval in milliseconds between each AbortCheck event callback, which enables an application to abort certain method calls before they complete. By default, HeartbeatMs is set to 0, meaning no AbortCheck event callbacks will trigger.
LastErrorHtml
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
Indicates the success or failure of the most recent method call: YES means success, NO 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.
MaxWaitMs
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
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 YES.
VerboseLogging
If set to YES, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is NO. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
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
supportsTls:(BOOL)supportsTls;
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 nil on 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)
domain:(NSString *)domain
answer:(CkoJsonObject *)answer;
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.
Returns nil on failure
RemoveAllNameservers
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 CkoBaseProgress. Your application can implement methods to override some or all of the default/empty method implementations of the CkoBaseProgress base class.
For example:
CkoDns *dns = [[CkoDns alloc] init]; MyDnsProgress *callbackObj = [[MyDnsProgress alloc] init]; [dns setEventCallbackObject:callbackObj];
MyDnsProgress interface example:
#import "CkoDnsProgress.h"
@interface MyDnsProgress : CkoBaseProgress {
}
- (id)init;
- (void)dealloc;
- (void)dispose;
- (void)AbortCheck:(BOOL *)abort;
- (void)PercentDone:(NSNumber *)pctDone
abort:(BOOL *)abort;
- (void)ProgressInfo:(NSString *)name
value:(NSString *)value;
- (void)TaskCompleted:(CkoTask *)task;
@endAbortCheck
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
PercentDone
abort:(BOOL *)abort;
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to YES. This will cause the method to terminate and return a failure status or corresponding failure value.
ProgressInfo
value:(NSString *)value;
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
TaskCompleted
Called from the background thread when an asynchronous task completes.