QDnsLookup 類

QDnsLookup 類錶示 DNS (域名係統) 查找。更多...

頭：	`#include <QDnsLookup>`
CMake:	`find_package(Qt6 REQUIRED COMPONENTS Network)` `target_link_libraries(mytarget PRIVATE Qt6::Network)`
qmake:	`QT += network`
繼承：	QObject

所有成員列錶，包括繼承成員
QDnsLookup is part of 網絡編程 API .

公共類型

enum	Error { NoError, ResolverError, OperationCancelledError, InvalidRequestError, InvalidReplyError, …, TimeoutError }
enum	Protocol { Standard, DnsOverTls }
enum	Type { A, AAAA, ANY, CNAME, MX, …, TXT }

特性

(從 6.8 起) authenticData : const bool
error : const Error
errorString : const QString
name : QString

nameserver : QHostAddress
(從 6.6 起) nameserverPort : quint16
(從 6.8 起) nameserverProtocol : Protocol
type : Type

公共函數

	QDnsLookup (QObject * parent = nullptr)
	QDnsLookup (QDnsLookup::Type type , const QString & name , QObject * parent = nullptr)
	QDnsLookup (QDnsLookup::Type type , const QString & name , const QHostAddress & nameserver , QObject * parent = nullptr)
`(從 6.6 起)`	QDnsLookup (QDnsLookup::Type type , const QString & name , const QHostAddress & nameserver , quint16 port , QObject * parent = nullptr)
`(從 6.8 起)`	QDnsLookup (QDnsLookup::Type type , const QString & name , QDnsLookup::Protocol protocol , const QHostAddress & nameserver , quint16 port = 0, QObject * parent = nullptr)
virtual	~QDnsLookup ()
QBindable<QString>	bindableName ()
QBindable<QHostAddress>	bindableNameserver ()
QBindable<quint16>	bindableNameserverPort ()
QBindable<QDnsLookup::Protocol>	bindableNameserverProtocol ()
QBindable<QDnsLookup::Type>	bindableType ()
QList<QDnsDomainNameRecord>	canonicalNameRecords () const
QDnsLookup::Error	error () const
QString	errorString () const
QList<QDnsHostAddressRecord>	hostAddressRecords () const
bool	isAuthenticData () const
bool	isFinished () const
QList<QDnsMailExchangeRecord>	mailExchangeRecords () const
QString	name () const
QList<QDnsDomainNameRecord>	nameServerRecords () const
QHostAddress	nameserver () const
quint16	nameserverPort () const
QDnsLookup::Protocol	nameserverProtocol () const
QList<QDnsDomainNameRecord>	pointerRecords () const
QList<QDnsServiceRecord>	serviceRecords () const
void	setName (const QString & name )
void	setNameserver (const QHostAddress & nameserver )
void	setNameserver (QDnsLookup::Protocol protocol , const QHostAddress & nameserver , quint16 port = 0)
`(從 6.6 起)` void	setNameserver (const QHostAddress & nameserver , quint16 port )
void	setNameserverPort (quint16 port )
void	setNameserverProtocol (QDnsLookup::Protocol protocol )
`(從 6.8 起)` void	setSslConfiguration (const QSslConfiguration & sslConfiguration )
void	setType (QDnsLookup::Type)
QSslConfiguration	sslConfiguration () const
QList<QDnsTextRecord>	textRecords () const
`(從 6.8 起)` QList<QDnsTlsAssociationRecord>	tlsAssociationRecords () const
QDnsLookup::Type	type () const

公共槽

void	abort ()
void	lookup ()

信號

void	finished ()
void	nameChanged (const QString & name )
void	nameserverChanged (const QHostAddress & nameserver )
void	nameserverPortChanged (quint16 port )
void	nameserverProtocolChanged (QDnsLookup::Protocol protocol )
void	typeChanged (QDnsLookup::Type type )

靜態公共成員

`(從 6.8 起)` quint16	defaultPortForProtocol (QDnsLookup::Protocol protocol )
`(從 6.8 起)` bool	isProtocolSupported (QDnsLookup::Protocol protocol )

詳細描述

QDnsLookup 使用由操作係統提供的機製來履行 DNS 查找。要履行查找需要指定 name and type 然後援引 lookup () slot. The finished () signal will be emitted upon completion.

例如，可以確定給定域的 XMPP 聊天客戶端應該連接到哪些服務器采用：

void MyObject::lookupServers()
{
    // Create a DNS lookup.
    dns = new QDnsLookup(this);
    connect(dns, &QDnsLookup::finished, this, &MyObject::handleServers);
    // Find the XMPP servers for gmail.com
    dns->setType(QDnsLookup::SRV);
    dns->setName("_xmpp-client._tcp.gmail.com");
    dns->lookup();
}

一旦請求完成，可以處理結果采用：

void MyObject::handleServers()
{
    // Check the lookup succeeded.
    if (dns->error() != QDnsLookup::NoError) {
        qWarning("DNS lookup failed");
        dns->deleteLater();
        return;
    }
    // Handle the results.
    const auto records = dns->serviceRecords();
    for (const QDnsServiceRecord &record : records) {
        ...
    }
    dns->deleteLater();
}

注意： 若僅僅希望查找與主機名關聯的 IP 地址 (或與 IP 地址關聯的主機名)，應該使用 QHostInfo 代替。

DNS-over-TLS and Authentic Data

QDnsLookup supports DNS-over-TLS (DoT, as specified by RFC 7858 ) on some platforms. That currently includes all Unix platforms where regular queries are supported, if QSslSocket support is present in Qt. To query if support is present at runtime, use isProtocolSupported ().

When using DNS-over-TLS, QDnsLookup only implements the "Opportunistic Privacy Profile" method of authentication, as described in RFC 7858 section 4.1. In this mode, QDnsLookup (through QSslSocket ) only validates that the server presents a certificate that is valid for the server being connected to. Clients may use setSslConfiguration () to impose additional restrictions and sslConfiguration () to obtain information after the query is complete.

QDnsLookup will request DNS servers queried over TLS to perform authentication on the data they return. If they confirm the data is valid, the authenticData property will be set to true. QDnsLookup does not verify the integrity of the data by itself, so applications should only trust this property on servers they have confirmed through other means to be trustworthy.

Authentic Data without TLS

QDnsLookup request Authentic Data for any server set with setNameserver (), even if TLS encryption is not required. This is useful when querying a caching nameserver on the same host as the application or on a trusted network. Though similar to the TLS case, the application is responsible for determining if the server it chose to use is trustworthy, and if the unencrypted connection cannot be tampered with.

QDnsLookup obeys the system configuration to request Authentic Data on the default nameserver (that is, if setNameserver () is not called). This is currently only supported on Linux systems using glibc 2.31 or later. On any other systems, QDnsLookup will ignore the AD bit in the query header.

成員類型文檔編製

enum QDnsLookup:: Error

指示在 DNS 查找處理過程中發現的所有可能的錯誤條件。

常量	值	描述
`QDnsLookup::NoError`	`0`	沒有錯誤條件。
`QDnsLookup::ResolverError`	`1`	初始化係統的 DNS 解析器時齣錯。
`QDnsLookup::OperationCancelledError`	`2`	查找被中止使用 abort () 方法。
`QDnsLookup::InvalidRequestError`	`3`	請求的 DNS 查找無效。
`QDnsLookup::InvalidReplyError`	`4`	由服務器返迴的迴復無效。
`QDnsLookup::ServerFailureError`	`5`	服務器遭遇內部故障當處理請求時 (SERVFAIL)。
`QDnsLookup::ServerRefusedError`	`6`	服務器齣於安全或策略原因拒絕處理請求 (REFUSED)。
`QDnsLookup::NotFoundError`	`7`	請求的域名不存在 (NXDOMAIN)。
`QDnsLookup::TimeoutError`	`8`	the server was not reached or did not reply in time (since 6.6).

enum QDnsLookup:: Protocol

Indicates the type of DNS server that is being queried.

常量	值	描述
`QDnsLookup::Standard`	`0`	Regular, unencrypted DNS, using UDP and falling back to TCP as necessary (default port: 53)
`QDnsLookup::DnsOverTls`	`1`	Encrypted DNS over TLS (DoT, as specified by RFC 7858 ), over TCP (default port: 853)

另請參閱 isProtocolSupported (), nameserverProtocol ，和 setNameserver ().

enum QDnsLookup:: Type

指示所履行的 DNS 查找類型。

常量	值	描述
`QDnsLookup::A`	`1`	IPv4 地址記錄。
`QDnsLookup::AAAA`	`28`	IPv6 地址記錄。
`QDnsLookup::ANY`	`255`	任何記錄。
`QDnsLookup::CNAME`	`5`	典型名稱記錄。
`QDnsLookup::MX`	`15`	郵件交換記錄。
`QDnsLookup::NS`	`2`	名稱服務器記錄。
`QDnsLookup::PTR`	`12`	指針記錄。
`QDnsLookup::SRV`	`33`	服務記錄。
`QDnsLookup::TLSA (since Qt 6.8)`	`52`	TLS association records.
`QDnsLookup::TXT`	`16`	文本記錄。

特性文檔編製

`[read-only, since 6.8]` authenticData : const bool

This property holds whether the reply was authenticated by the resolver.

QDnsLookup does not perform the authentication itself. Instead, it trusts the name server that was queried to perform the authentication and report it. The application is responsible for determining if any servers it configured with setNameserver () are trustworthy; if no server was set, QDnsLookup obeys system configuration on whether responses should be trusted.

This property may be set even if error () indicates a resolver error occurred.

該特性在 Qt 6.8 引入。

訪問函數：

bool	isAuthenticData () const

通知程序信號：

void	finished ()

另請參閱 setNameserver () 和 nameserverProtocol ().

`[read-only]` error : const Error

此特性保持齣現錯誤的類型若 DNS 查找失敗，或 NoError .

訪問函數：

QDnsLookup::Error error () const

通知程序信號：

void	finished ()

`[read-only]` errorString : const QString

此特性保持錯誤的人類可讀描述，若 DNS 查找失敗。

訪問函數：

QString errorString () const

通知程序信號：

void	finished ()

`[bindable]` 名稱 : QString

注意： 此特性支持 QProperty 綁定。

此特性保持要查找的名稱。

If the name to look up is empty, QDnsLookup will attempt to resolve the root domain of DNS. That query is usually performed with QDnsLookup::type 設為 NS .

注意： 名稱將使用 IDNA 編碼，這意味著它不適閤查詢兼容 DNS-SD 規範的 SRV 記錄。

訪問函數：

QString	名稱 () const
void	setName (const QString & name )

通知程序信號：

void	nameChanged (const QString & name )

`[bindable]` nameserver : QHostAddress

注意： 此特性支持 QProperty 綁定。

此特性保持用於 DNS 查找的名稱服務器。

訪問函數：

QHostAddress	nameserver () const
void	setNameserver (const QHostAddress & nameserver )
void	setNameserver (QDnsLookup::Protocol protocol , const QHostAddress & nameserver , quint16 port = 0)
void	setNameserver (const QHostAddress & nameserver , quint16 port )

通知程序信號：

void	nameserverChanged (const QHostAddress & nameserver )

`[bindable, since 6.6]` nameserverPort : quint16

注意： 此特性支持 QProperty 綁定。

This property holds the port number of nameserver to use for DNS lookup.

The value of 0 indicates that QDnsLookup should use the default port for the nameserverProtocol ().

注意： Setting the port number to any value other than the default (53) can cause the name resolution to fail, depending on the operating system limitations and firewalls, if the nameserverProtocol () to be used QDnsLookup::Standard . Notably, the Windows API used by QDnsLookup is unable to handle alternate port numbers.

該特性在 Qt 6.6 引入。

訪問函數：

quint16	nameserverPort () const
void	setNameserverPort (quint16 port )

通知程序信號：

void	nameserverPortChanged (quint16 port )

`[bindable, since 6.8]` nameserverProtocol : Protocol

注意： 此特性支持 QProperty 綁定。

This property holds the protocol to use when sending the DNS query

該特性在 Qt 6.8 引入。

訪問函數：

QDnsLookup::Protocol	nameserverProtocol () const
void	setNameserverProtocol (QDnsLookup::Protocol protocol )

通知程序信號：

void	nameserverProtocolChanged (QDnsLookup::Protocol protocol )

另請參閱 isProtocolSupported ().

`[bindable]` type : Type

注意： 此特性支持 QProperty 綁定。

此特性保持 DNS 查找的類型。

訪問函數：

QDnsLookup::Type	type () const
void	setType (QDnsLookup::Type)

通知程序信號：

void	typeChanged (QDnsLookup::Type type )

成員函數文檔編製

`[explicit]` QDnsLookup:: QDnsLookup ( QObject * parent = nullptr)

構造 QDnsLookup 對象並設置 parent 作為父級對象。

The type 特性默認為 QDnsLookup::A .

QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , QObject * parent = nullptr)

構造 QDnsLookup 對象為給定 type and name 並設置 parent 作為父級對象。

QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , const QHostAddress & nameserver , QObject * parent = nullptr)

Constructs a QDnsLookup object to issue a query for name of record type type , using the DNS server nameserver running on the default DNS port, and sets parent 作為父級對象。

`[since 6.6]` QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , const QHostAddress & nameserver , quint16 port , QObject * parent = nullptr)

Constructs a QDnsLookup object to issue a query for name of record type type , using the DNS server nameserver running on port port , and sets parent 作為父級對象。

該函數在 Qt 6.6 引入。

`[since 6.8]` QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , QDnsLookup::Protocol protocol , const QHostAddress & nameserver , quint16 port = 0, QObject * parent = nullptr)

Constructs a QDnsLookup object to issue a query for name of record type type , using the DNS server nameserver running on port port , and sets parent 作為父級對象。

The query will be sent using protocol , if supported. Use isProtocolSupported () to check if it is supported.

該函數在 Qt 6.8 引入。

`[virtual noexcept]` QDnsLookup:: ~QDnsLookup ()

銷毀 QDnsLookup 對象。

它是安全的刪除 QDnsLookup 對象即使它尚未完成，簡而言之，也從不會收到其結果。

`[slot]` void QDnsLookup:: abort ()

中止 DNS 查找操作。

若查找已完成，什麼都不做。

QList < QDnsDomainNameRecord > QDnsLookup:: canonicalNameRecords () const

返迴關聯此查找的典型名稱記錄列錶。

`[static noexcept, since 6.8]` quint16 QDnsLookup:: defaultPortForProtocol ( QDnsLookup::Protocol protocol )

Returns the standard (default) port number for the protocol protocol .

該函數在 Qt 6.8 引入。

另請參閱 isProtocolSupported ().

`[signal]` void QDnsLookup:: finished ()

此信號被發射，當迴復已處理完成。

注意： 通知程序信號對於特性 authenticData , error ，和 errorString .

QList < QDnsHostAddressRecord > QDnsLookup:: hostAddressRecords () const

返迴關聯此查找的主機地址記錄列錶。

bool QDnsLookup:: isFinished () const

返迴迴復是已完成還是被中止。

`[static, since 6.8]` bool QDnsLookup:: isProtocolSupported ( QDnsLookup::Protocol protocol )

Returns true if DNS queries using protocol are supported with QDnsLookup .

該函數在 Qt 6.8 引入。

另請參閱 nameserverProtocol .

`[slot]` void QDnsLookup:: lookup ()

履行 DNS 查找。

The finished () signal is emitted upon completion.

QList < QDnsMailExchangeRecord > QDnsLookup:: mailExchangeRecords () const

返迴關聯此查找的郵件交換記錄列錶。

記錄的排序是根據 RFC 5321 ，因此，若使用它們連接到服務器，應按照列錶它們的次序嘗試。

`[signal]` void QDnsLookup:: nameChanged (const QString & name )

此信號發射，當查找 name 改變。 name 是新的查找名稱。

注意： 通知程序信號對於特性 name .

QList < QDnsDomainNameRecord > QDnsLookup:: nameServerRecords () const

返迴關聯此查找的名稱服務器記錄列錶。

QList < QDnsDomainNameRecord > QDnsLookup:: pointerRecords () const

返迴關聯此查找的指針記錄列錶。

QList < QDnsServiceRecord > QDnsLookup:: serviceRecords () const

返迴關聯此查找的服務記錄列錶。

記錄的排序是根據 RFC 2782 ，因此，若使用它們連接到服務器，應按照列錶它們的次序嘗試。

`[since 6.6]` void QDnsLookup:: setNameserver (const QHostAddress & nameserver , quint16 port )

Sets the nameserver to nameserver and the port to port .

注意： setter 函數對於特性 nameserver .

該函數在 Qt 6.6 引入。

另請參閱 QDnsLookup::nameserver and QDnsLookup::nameserverPort .

`[since 6.8]` void QDnsLookup:: setSslConfiguration (const QSslConfiguration & sslConfiguration )

設置 sslConfiguration to use for outgoing DNS-over-TLS connections.

該函數在 Qt 6.8 引入。

另請參閱 sslConfiguration () 和 QSslSocket::setSslConfiguration ().

QSslConfiguration QDnsLookup:: sslConfiguration () const

Returns the current SSL configuration.

另請參閱 setSslConfiguration ().

QList < QDnsTextRecord > QDnsLookup:: textRecords () const

返迴關聯此查找的文本記錄列錶。

`[since 6.8]` QList < QDnsTlsAssociationRecord > QDnsLookup:: tlsAssociationRecords () const

Returns the list of TLS association records associated with this lookup.

According to the standards relating to DNS-based Authentication of Named Entities (DANE), this field should be ignored and must not be used for verifying the authentity of a given server if the authenticity of the DNS reply cannot itself be confirmed. See isAuthenticData () 瞭解更多信息。

該函數在 Qt 6.8 引入。

`[signal]` void QDnsLookup:: typeChanged ( QDnsLookup::Type type )

此信號發射，當查找 type 改變。 type 是新的查找類型。

注意： 通知程序信號對於特性 type .

QDnsLookup 類

公共類型

特性

公共函數

公共槽

信號

靜態公共成員

詳細描述

DNS-over-TLS and Authentic Data

Authentic Data without TLS

成員類型文檔編製

enum QDnsLookup:: Error

enum QDnsLookup:: Protocol

enum QDnsLookup:: Type

特性文檔編製

[read-only, since 6.8] authenticData : const bool

[read-only] error : const Error

[read-only] errorString : const QString

[bindable] 名稱 : QString

[bindable] nameserver : QHostAddress

[bindable, since 6.6] nameserverPort : quint16

[bindable, since 6.8] nameserverProtocol : Protocol

[bindable] type : Type

成員函數文檔編製

[explicit] QDnsLookup:: QDnsLookup ( QObject * parent = nullptr)

QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , QObject * parent = nullptr)

QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , const QHostAddress & nameserver , QObject * parent = nullptr)

[since 6.6] QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , const QHostAddress & nameserver , quint16 port , QObject * parent = nullptr)

[since 6.8] QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , QDnsLookup::Protocol protocol , const QHostAddress & nameserver , quint16 port = 0, QObject * parent = nullptr)

[virtual noexcept] QDnsLookup:: ~QDnsLookup ()

[slot] void QDnsLookup:: abort ()

QList < QDnsDomainNameRecord > QDnsLookup:: canonicalNameRecords () const

[static noexcept, since 6.8] quint16 QDnsLookup:: defaultPortForProtocol ( QDnsLookup::Protocol protocol )

[signal] void QDnsLookup:: finished ()

QList < QDnsHostAddressRecord > QDnsLookup:: hostAddressRecords () const

bool QDnsLookup:: isFinished () const

[static, since 6.8] bool QDnsLookup:: isProtocolSupported ( QDnsLookup::Protocol protocol )

[slot] void QDnsLookup:: lookup ()

QList < QDnsMailExchangeRecord > QDnsLookup:: mailExchangeRecords () const

[signal] void QDnsLookup:: nameChanged (const QString & name )

QList < QDnsDomainNameRecord > QDnsLookup:: nameServerRecords () const

QList < QDnsDomainNameRecord > QDnsLookup:: pointerRecords () const

QList < QDnsServiceRecord > QDnsLookup:: serviceRecords () const

[since 6.6] void QDnsLookup:: setNameserver (const QHostAddress & nameserver , quint16 port )

[since 6.8] void QDnsLookup:: setSslConfiguration (const QSslConfiguration & sslConfiguration )

QSslConfiguration QDnsLookup:: sslConfiguration () const

QList < QDnsTextRecord > QDnsLookup:: textRecords () const

[since 6.8] QList < QDnsTlsAssociationRecord > QDnsLookup:: tlsAssociationRecords () const

[signal] void QDnsLookup:: typeChanged ( QDnsLookup::Type type )

內容

`[read-only, since 6.8]` authenticData : const bool

`[read-only]` error : const Error

`[read-only]` errorString : const QString

`[bindable]` 名稱 : QString

`[bindable]` nameserver : QHostAddress

`[bindable, since 6.6]` nameserverPort : quint16

`[bindable, since 6.8]` nameserverProtocol : Protocol

`[bindable]` type : Type

`[explicit]` QDnsLookup:: QDnsLookup ( QObject * parent = nullptr)

`[since 6.6]` QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , const QHostAddress & nameserver , quint16 port , QObject * parent = nullptr)

`[since 6.8]` QDnsLookup:: QDnsLookup ( QDnsLookup::Type type , const QString & name , QDnsLookup::Protocol protocol , const QHostAddress & nameserver , quint16 port = 0, QObject * parent = nullptr)

`[virtual noexcept]` QDnsLookup:: ~QDnsLookup ()

`[slot]` void QDnsLookup:: abort ()

`[static noexcept, since 6.8]` quint16 QDnsLookup:: defaultPortForProtocol ( QDnsLookup::Protocol protocol )

`[signal]` void QDnsLookup:: finished ()

`[static, since 6.8]` bool QDnsLookup:: isProtocolSupported ( QDnsLookup::Protocol protocol )

`[slot]` void QDnsLookup:: lookup ()

`[signal]` void QDnsLookup:: nameChanged (const QString & name )

`[since 6.6]` void QDnsLookup:: setNameserver (const QHostAddress & nameserver , quint16 port )

`[since 6.8]` void QDnsLookup:: setSslConfiguration (const QSslConfiguration & sslConfiguration )

`[since 6.8]` QList < QDnsTlsAssociationRecord > QDnsLookup:: tlsAssociationRecords () const

`[signal]` void QDnsLookup:: typeChanged ( QDnsLookup::Type type )