Struct ipworks::DNS

Properties   Methods   Events   Config Settings   Errors  

The DNS struct is used to query DNS for record information.

Syntax

ipworks::DNS

Remarks

The DNS struct queries a DNS server for records as specified in RFC 1035 and other relevant RFCs. The struct property query_type indicates the record to be queried. Calling query will initiate the query.

Once the query is complete, a single on_response event will fire and the record properties will be filled. status_code is the server's success or fail code, and status is a standard string interpretation of the code.

The records are contained in the records properties. The programming interface is designed to allow a full walk of the records in the DNS response, including provisions for handling new record types.

The struct operates synchronously by default (i.e., it waits for a response before returning control to the caller); however, the struct also may operate asynchronously (i.e., return control immediately), by setting timeout to 0. Please see the timeout property for more information.

Object Lifetime

The new() method returns a mutable reference to a struct instance. The object itself is kept in the global list maintained by IPWorks. Due to this, the DNS struct cannot be disposed of automatically. Please, call the dispose(&mut self) method of DNS when you have finished using the instance.

Property List

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

dns_port property (DNS Struct)

This is the port to connect to on the DNS server.

Syntax

fn dns_port(&self ) -> Result<i32, IPWorksError> 
fn set_dns_port(&self, value : i32) ->  Option<IPWorksError> 

Default Value

53

Remarks

This property contains the port to connect to on the DNS server. A valid port number (a value between 1 and 65535) is required for the connection to take place. The property must be set before a connection is attempted and cannot be changed once a connection is established. Any attempt to change this property while connected will fail with an error.

Data Type

i32

dns_server property (DNS Struct)

This is the address of the DNS server.

Syntax

fn dns_server(&self ) -> Result<String, IPWorksError> 
fn set_dns_server(&self, value : &str) ->  Option<IPWorksError> 
fn set_dns_server_ref(&self, value : &String) ->  Option<IPWorksError> 

Default Value

""

Remarks

This property contains the address of the DNS server. The struct attempts to find the default DNS server for the machine where it is installed, and provide it in the dns_server property. You may change it to any particular DNS server you want to query. While any internet host running a DNS service will suffice, it is preferable to use either the DNS server for your network or the DNS server for the domain that you are querying.

If the struct cannot determine the default DNS server address, the property value will be an empty string.

NOTE: Automatic discovery of the default DNS server is not supported in the Java edition.

Data Type

String

idle property (DNS Struct)

The current status of the struct.

Syntax

fn idle(&self ) -> Result<bool, IPWorksError> 

Default Value

true

Remarks

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

This property is read-only.

Data Type

bool

local_host property (DNS Struct)

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

Syntax

fn local_host(&self ) -> Result<String, IPWorksError> 
fn set_local_host(&self, value : &str) ->  Option<IPWorksError> 
fn set_local_host_ref(&self, value : &String) ->  Option<IPWorksError> 

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 struct initiate connections (or accept in the case of server structs) 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 struct is connected, the local_host 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: local_host is not persistent. You must always set it in code, and never in the property window.

Data Type

String

protocol property (DNS Struct)

This protocol is used for the DNS request.

Syntax

fn protocol(&self ) -> Result<i32, IPWorksError> 
fn set_protocol(&self, value : i32) ->  Option<IPWorksError> 

Possible Values

0   // UDP
1   // TCP
2   // TLS
3   // HTTPS

Default Value

0

Remarks

This property specifies the protocol used for the DNS request when query is called. Possible values include the following:

Data Type

i32

query_type property (DNS Struct)

This is the type of record to query.

Syntax

fn query_type(&self ) -> Result<i32, IPWorksError> 
fn set_query_type(&self, value : i32) ->  Option<IPWorksError> 

Possible Values

1   // Address
2   // NS
3   // MD
4   // MF
5   // CName
6   // SOA
7   // MailBox
8   // MailGroup
9   // MR
10   // NULL
11   // WKS
12   // Pointer
13   // HostInfo
14   // MailInfo
15   // MX
16   // Text
17   // RP
18   // AFSDB
19   // X25
20   // ISDN
21   // RT
28   // AAAA
33   // SRV
35   // NAPTR
37   // CERT
100   // RevLookup

Default Value

1

Remarks

Before a query is attempted, this property must be set to the desired record type. The records are defined as follows:

Data Type

i32

record_count property (DNS Struct)

The number of records in the Record arrays.

Syntax

fn record_count(&self ) -> Result<i32, IPWorksError> 

Default Value

0

Remarks

This property controls the size of the following arrays:

• record_data
• record_domain
• record_field_count
• record_field_index
• record_field_name
• record_field_value
• record_ttl
• record_type
• record_type_name

The array indices start at 0 and end at record_count - 1.

This property is read-only.

Data Type

i32

record_domain property (DNS Struct)

This property contains the domain name associated with the selected response record, at RecordIndex .

Syntax

fn record_domain(&self , RecordIndex : i32) -> Result<String, IPWorksError> 

Default Value

""

Remarks

This property contains the domain name associated with the selected response record, at RecordIndex.

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

This property is read-only.

Data Type

String

record_field_count property (DNS Struct)

This property contains the number of properties in the current record.

Syntax

fn record_field_count(&self , RecordIndex : i32) -> Result<i32, IPWorksError> 

Default Value

0

Remarks

This property contains the number of properties in the current record.

After a successful query, the field values for each record will be provided in the records properties.

To retrieve a particular field value for a record, first set record_field_index to a valid response field index and then query records collection for the value of that field.

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

This property is read-only.

Data Type

i32

record_field_index property (DNS Struct)

This property contains the index of the selected property of the current record.

Syntax

fn record_field_index(&self , RecordIndex : i32) -> Result<i32, IPWorksError> 
fn set_record_field_index(&self, RecordIndex : i32, value : i32) ->  Option<IPWorksError> 

Default Value

1

Remarks

This property contains the index of the selected property of the current record. record_field_index valid values are from 0 to (record_field_count -1).

After a successful query, the field values for each record will be provided in the records properties.

To retrieve a particular field value for a record, first set record_field_index to a valid response field index and then query records collection for the value of that field.

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

Data Type

i32

record_field_name property (DNS Struct)

This property contains the name of the property selected by FieldIndex .

Syntax

fn record_field_name(&self , RecordIndex : i32) -> Result<String, IPWorksError> 

Default Value

"0"

Remarks

This property contains the name of the field selected by record_field_index. Field names are different depending on the record type. For example, an MX record type will contain two properties: PREFERENCE and EXCHANGE, but an SOA record type contains seven properties.

Field names:

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

This property is read-only.

Data Type

String

record_field_value property (DNS Struct)

This property contains the value of the property selected by FieldIndex .

Syntax

fn record_field_value(&self , RecordIndex : i32) -> Result<Vec<u8>, IPWorksError> 

Default Value

""

Remarks

This property contains the value of the field selected by record_field_index.

After a successful query, the field values for each record will be provided in the records properties.

To retrieve a particular field value for a record, first set record_field_index to a valid response field index and then query records collection for the value of that field.

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

This property is read-only.

Data Type

Vec

record_data property (DNS Struct)

This property contains the full record data as received from the DNS server.

Syntax

fn record_data(&self , RecordIndex : i32) -> Result<Vec<u8>, IPWorksError> 

Default Value

""

Remarks

This property contains the full record data as received from the DNS server.

After a successful query, the field values for each record will be provided in the records properties.

To retrieve a particular field value for a record, first set record_field_index to a valid response field index and then query records collection for the value of that field.

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

This property is read-only.

Data Type

Vec

record_type property (DNS Struct)

This property contains the record type.

Syntax

fn record_type(&self , RecordIndex : i32) -> Result<i32, IPWorksError> 

Possible Values

1   // Address
2   // NS
3   // MD
4   // MF
5   // CName
6   // SOA
7   // MailBox
8   // MailGroup
9   // MR
10   // NULL
11   // WKS
12   // Pointer
13   // HostInfo
14   // MailInfo
15   // MX
16   // Text
17   // RP
18   // AFSDB
19   // X25
20   // ISDN
21   // RT
28   // AAAA
33   // SRV
35   // NAPTR

Default Value

1

Remarks

This property contains the record type.

Record types correspond to query_type and are defined as follows:

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

This property is read-only.

Data Type

i32

record_type_name property (DNS Struct)

This property contains the string representation of the current record type defined by RecordType .

Syntax

fn record_type_name(&self , RecordIndex : i32) -> Result<String, IPWorksError> 

Default Value

""

Remarks

This property contains the string representation of the current record type defined by record_record_type.

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

This property is read-only.

Data Type

String

record_ttl property (DNS Struct)

This property contains the record Time to Live (TTL) value.

Syntax

fn record_ttl(&self , RecordIndex : i32) -> Result<i32, IPWorksError> 

Default Value

0

Remarks

This property contains the record Time to Live (TTL) value. The TTL specifies the time interval in seconds that the record is valid, or the time interval that the record can be cached before the DNS server should be queried again.

The RecordIndex parameter specifies the index of the item in the array. The size of the array is controlled by the RecordCount property.

This property is read-only.

Data Type

i32

record_source property (DNS Struct)

The source of records provided in the Records properties.

Syntax

fn record_source(&self ) -> Result<i32, IPWorksError> 
fn set_record_source(&self, value : i32) ->  Option<IPWorksError> 

Possible Values

0   // AnswerSection
1   // NameServerSection
2   // AdditionalRecordsSection

Default Value

0

Remarks

This property contains the source of records provided in the records properties and can have one of the following values:

Data Type

i32

recursive property (DNS Struct)

This determines whether to ask the DNSServer to recursively query other servers.

Syntax

fn recursive(&self ) -> Result<bool, IPWorksError> 
fn set_recursive(&self, value : bool) ->  Option<IPWorksError> 

Default Value

true

Remarks

If this property is True, the component will tell the DNS server to perform the query recursively. This means that if the DNS server does not have information about the domain being queried, it will send the request to another DNS server.

Data Type

bool

request_id property (DNS Struct)

This is the Id of the current DNS request.

Syntax

fn request_id(&self ) -> Result<i32, IPWorksError> 
fn set_request_id(&self, value : i32) ->  Option<IPWorksError> 

Default Value

1

Remarks

This property is the identifier of the request that generated the current response values. Each time the struct makes a DNS query, it generates a unique request identifier to track the response.

If a custom value is needed for request_id, the property must be set before sending a request. The struct increments request_id automatically after sending each request.

NOTE: The struct fails with an error when a value that is not between 1 and 32,767 is specified.

Data Type

i32

status property (DNS Struct)

This is a standard string interpretation of StatusCode .

Syntax

fn status(&self ) -> Result<String, IPWorksError> 

Default Value

""

Remarks

This property contains a standard string interpretation of status_code. For a list of valid error codes and their descriptions, please see the Error Codes section.

This property is read-only.

Data Type

String

status_code property (DNS Struct)

This contains the success or error code for the DNS query.

Syntax

fn status_code(&self ) -> Result<i32, IPWorksError> 

Default Value

0

Remarks

This property contains the success or error code for the DNS query. For a list of valid error codes and their descriptions, please see the Error Codes section.

This property is read-only.

Data Type

i32

timeout property (DNS Struct)

This property includes the timeout for the struct.

Syntax

fn timeout(&self ) -> Result<i32, IPWorksError> 
fn set_timeout(&self, value : i32) ->  Option<IPWorksError> 

Default Value

60

Remarks

If the timeout property is set to 0, all operations return immediately, potentially failing with a WOULDBLOCK error if data cannot be sent immediately.

If timeout is set to a positive value, data is sent in a blocking manner and the struct will wait for the operation to complete before returning control. The struct will handle any potential WOULDBLOCK errors internally and automatically retry the operation for a maximum of timeout seconds.

The struct will use do_events 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 struct 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 60 seconds.

Data Type

i32

config method (DNS Struct)

Sets or retrieves a configuration setting.

Syntax

fn config(&self, configuration_string : &str) ->  Result<String, IPWorksError>

Remarks

config is a generic method available in every struct. It is used to set and retrieve configuration settings for the struct.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the struct, 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.

do_events method (DNS Struct)

This method processes events from the internal message queue.

Syntax

fn do_events(&self) -> Result<(), IPWorksError>

Remarks

When do_events is called, the struct processes any available events. If no events are available, it waits for a preset period of time, and then returns.

get_field_value method (DNS Struct)

This gets the value of the field indicated from a record.

Syntax

fn get_field_value(&self, record_index : i32, field_name : &str) ->  Result<String, IPWorksError>

Remarks

This method will get the value of the DNS record field specified by field_name from the DNS record at record_index. If no such field exists for that record type, the component fails with an error.

interrupt method (DNS Struct)

This method interrupts the current method.

Syntax

fn interrupt(&self) -> Result<(), IPWorksError>

Remarks

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

query method (DNS Struct)

This method queries a domain.

Syntax

fn query(&self, domain : &str) -> Result<(), IPWorksError>

Remarks

This method will query the host domain for any records of the type in query_type. After the query, request_id is the identifier corresponding to the request. Once the query is complete, a single on_response event will fire. The following properties will contain the results:

reset method (DNS Struct)

This method will reset the struct.

Syntax

fn reset(&self) -> Result<(), IPWorksError>

Remarks

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

on_error event (DNS Struct)

Fired when information is available about errors during data delivery.

Syntax

// DNSErrorEventArgs carries the DNS Error event's parameters.
pub struct DNSErrorEventArgs {
  fn error_code(&self) -> i32
  fn description(&self) -> &String
}

// DNSErrorEvent defines the signature of the DNS Error event's handler function.
pub trait DNSErrorEvent {
  fn on_error(&self, sender : DNS, e : &mut DNSErrorEventArgs);
}

impl <'a> DNS<'a> {
  pub fn on_error(&self) -> &'a dyn DNSErrorEvent;
  pub fn set_on_error(&mut self, value : &'a dyn DNSErrorEvent);
  ...
}

Remarks

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

The error_code 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.

on_log event (DNS Struct)

This event fires once for each log message.

Syntax

// DNSLogEventArgs carries the DNS Log event's parameters.
pub struct DNSLogEventArgs {
  fn log_level(&self) -> i32
  fn message(&self) -> &String
  fn log_type(&self) -> &String
}

// DNSLogEvent defines the signature of the DNS Log event's handler function.
pub trait DNSLogEvent {
  fn on_log(&self, sender : DNS, e : &mut DNSLogEventArgs);
}

impl <'a> DNS<'a> {
  pub fn on_log(&self) -> &'a dyn DNSLogEvent;
  pub fn set_on_log(&mut self, value : &'a dyn DNSLogEvent);
  ...
}

Remarks

This event fires once for each log message generated by the struct. The verbosity is controlled by the LogLevel setting.

log_level indicates the level of message. Possible values are as follows:

The value 1 (Info) logs basic information, including the URL, HTTP version, and status details.

The value 2 (Verbose) logs additional information about the request and response.

The value 3 (Debug) logs the headers and body for both the request and response, as well as additional debug information (if any).

message is the log entry.

log_type identifies the type of log entry. Possible values are as follows:

• "Info"
• "RequestHeaders"
• "ResponseHeaders"
• "RequestBody"
• "ResponseBody"
• "ProxyRequest"
• "ProxyResponse"
• "FirewallRequest"
• "FirewallResponse"

on_response event (DNS Struct)

This event fires after a DNS query.

Syntax

// DNSResponseEventArgs carries the DNS Response event's parameters.
pub struct DNSResponseEventArgs {
  fn request_id(&self) -> i32
  fn domain(&self) -> &String
  fn status_code(&self) -> i32
  fn description(&self) -> &String
  fn authoritative(&self) -> bool
}

// DNSResponseEvent defines the signature of the DNS Response event's handler function.
pub trait DNSResponseEvent {
  fn on_response(&self, sender : DNS, e : &mut DNSResponseEventArgs);
}

impl <'a> DNS<'a> {
  pub fn on_response(&self) -> &'a dyn DNSResponseEvent;
  pub fn set_on_response(&mut self, value : &'a dyn DNSResponseEvent);
  ...
}

Remarks

The on_response event will fire after a call to query. The request_id parameter contains the request Id associated with the original query. domain is the domain of the query. The authoritative parameter is true if the response is from an authoritative name server. If there is an error returned by the server, status_code and description provide them.

Once the query is complete, a single on_response event will fire. The following properties will contain the results:

on_ssl_server_authentication event (DNS Struct)

This event fires when connecting to the server.

Syntax

// DNSSSLServerAuthenticationEventArgs carries the DNS SSLServerAuthentication event's parameters.
pub struct DNSSSLServerAuthenticationEventArgs {
  fn remote_address(&self) -> &String
  fn remote_port(&self) -> i32
  fn cert_encoded(&self) -> &[u8]
  fn cert_subject(&self) -> &String
  fn cert_issuer(&self) -> &String
  fn status(&self) -> &String
  fn accept(&self) -> bool
  fn set_accept(&self, value : bool)
}

// DNSSSLServerAuthenticationEvent defines the signature of the DNS SSLServerAuthentication event's handler function.
pub trait DNSSSLServerAuthenticationEvent {
  fn on_ssl_server_authentication(&self, sender : DNS, e : &mut DNSSSLServerAuthenticationEventArgs);
}

impl <'a> DNS<'a> {
  pub fn on_ssl_server_authentication(&self) -> &'a dyn DNSSSLServerAuthenticationEvent;
  pub fn set_on_ssl_server_authentication(&mut self, value : &'a dyn DNSSSLServerAuthenticationEvent);
  ...
}

Remarks

This event allows the client to decide whether or not to continue with the connection process. The Accept parameter recommends whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string "OK"). If the client decides to continue, you can override and accept the certificate by setting the Accept parameter to True.

remote_address is the IP address of the server.

remote_port is the source port of the server.

cert_encoded is the Base64-encoded certificate presented by the server.

cert_subject is the subject of the certificate presented by the server.

cert_issuer is the subject of the issuer of the certificate presented by the server.

status is the status of the certificate.

accept defines whether the certificate is accepted.

on_ssl_status event (DNS Struct)

This shows the progress of the secure connection.

Syntax

// DNSSSLStatusEventArgs carries the DNS SSLStatus event's parameters.
pub struct DNSSSLStatusEventArgs {
  fn remote_address(&self) -> &String
  fn remote_port(&self) -> i32
  fn message(&self) -> &String
}

// DNSSSLStatusEvent defines the signature of the DNS SSLStatus event's handler function.
pub trait DNSSSLStatusEvent {
  fn on_ssl_status(&self, sender : DNS, e : &mut DNSSSLStatusEventArgs);
}

impl <'a> DNS<'a> {
  pub fn on_ssl_status(&self) -> &'a dyn DNSSSLStatusEvent;
  pub fn set_on_ssl_status(&mut self, value : &'a dyn DNSSSLStatusEvent);
  ...
}

Remarks

The event is fired for informational and logging purposes only. It is used to track the progress of the connection.

remote_address is the IP address of the remote machine.

remote_port is the port of the remote machine.

message is the log message.

Config Settings (DNS Struct)

The struct 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 struct, access to these internal properties is provided through the config method.

DNS Config Settings

UDP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (DNS Struct)

DNS Errors

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

UDP Errors

SSL Errors

TCP/IP Errors