Dns Tcl Reference Documentation

Dns

Current Version: 9.5.0.97

API for managing DNS nameservers to be used by Chilkat, and for doing DNS queries.

Object Creation

set myDns [new CkDns]

Properties

DebugLogFilePath
string
# ckStr is a CkString
CkDns_get_DebugLogFilePath $myDns $ckStr
set strVal [CkDns_get_debugLogFilePath $myDns]
CkDns_put_DebugLogFilePath $myDns $strVal

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

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LastErrorHtml
string
# ckStr is a CkString
CkDns_get_LastErrorHtml $myDns $ckStr
set strVal [CkDns_get_lastErrorHtml $myDns]

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
string
# ckStr is a CkString
CkDns_get_LastErrorText $myDns $ckStr
set strVal [CkDns_get_lastErrorText $myDns]

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
string
# ckStr is a CkString
CkDns_get_LastErrorXml $myDns $ckStr
set strVal [CkDns_get_lastErrorXml $myDns]

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
boolean 1/0
set boolVal [CkDns_get_LastMethodSuccess $myDns]
CkDns_put_LastMethodSuccess $myDns $boolVal

Indicate whether the last method call succeeded or failed. A value of 1 indicates success, a value of 0 indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = 1 and failure = 0.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to 1. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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MaxWaitMs
integer
set intVal [CkDns_get_MaxWaitMs $myDns]
CkDns_put_MaxWaitMs $myDns $intVal
Introduced in version 9.5.0.96

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.

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NumNameservers
integer
set intVal [CkDns_get_NumNameservers $myDns]
Introduced in version 9.5.0.96

The number of nameservers currently being used by Chilkat for DNS queries in all objects/classes, such as for HTTP, Email, FTP, SSH, etc.

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TlsPref
integer
set intVal [CkDns_get_TlsPref $myDns]
CkDns_put_TlsPref $myDns $intVal
Introduced in version 9.5.0.96

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 1.

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Utf8
boolean 1/0
set boolVal [CkDns_get_Utf8 $myDns]
CkDns_put_Utf8 $myDns $boolVal

When set to 1, all "const char *" arguments are interpreted as utf-8 strings. If set to 0 (the default), then "const char *" arguments are interpreted as ANSI strings. Also, when set to 1, and Chilkat method returning a "const char *" is returning the utf-8 representation. If set to 0, all "const char *" return values are ANSI strings.

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VerboseLogging
boolean 1/0
set boolVal [CkDns_get_VerboseLogging $myDns]
CkDns_put_VerboseLogging $myDns $boolVal

If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
string
# ckStr is a CkString
CkDns_get_Version $myDns $ckStr
set strVal [CkDns_get_version $myDns]

Version of the component/library, such as "9.5.0.94"

More Information and Examples
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Methods

AddDefaultNameservers
CkDns_AddDefaultNameservers
Introduced in version 9.5.0.96

Adds the default (auto-assigned) nameservers to the collection of nameservers used by Chilkat for DNS queries and domain to IP address lookups.

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AddNameserver
# ipAddr is a string
# supportsTls is a boolean
CkDns_AddNameserver $ipAddr $supportsTls
Introduced in version 9.5.0.96

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.

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GetNameserver
# index is an integer
# outStr is a CkString (output)
set status [CkDns_GetNameserver $index $outStr]
set retStr [CkDns_getNameserver $myDns $index]
Introduced in version 9.5.0.96

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 1 for success, 0 for failure.

More Information and Examples
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Query
# recordType is a string
# domain is a string
# answer is a CkJsonObject
set retBool [CkDns_Query $recordType $domain $answer]
Introduced in version 9.5.0.96

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.

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QueryAsync (1)
# returns a CkTask
# recordType is a string
# domain is a string
# answer is a CkJsonObject
set ret_task [CkDns_QueryAsync $recordType $domain $answer]
Introduced in version 9.5.0.96

Creates an asynchronous task to call the Query method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns NULL on failure

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RemoveAllNameservers
CkDns_RemoveAllNameservers
Introduced in version 9.5.0.96

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.

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RemoveNameserver
# ipAddr is a string
CkDns_RemoveNameserver $ipAddr
Introduced in version 9.5.0.96

Removes a nameserver from the collection of nameservers used by Chilkat. The ipAddr is the IPv4 address of the nameserver to be removed.

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