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The QDns class provides asynchronous DNS lookups. More...
#include <qdns.h>
Inherits QObject.
Both Windows and UNIX provides synchronous DNS lookups; Windows provides some asynchronous support too. Neither OS provides asynchronous support for anything other than hostname-to-address mapping.
QDns rectifies that, by providing asynchronous caching lookups for the record types that we expect modern GUI applications to need in the near future.
The class is a bit hard to use (although much simpler than the native APIs); QSocket provides much simpler TCP connection facilities. The aim of QDns is to provide a correct and small API to the DNS: Nothing more. (Correctness implies that the DNS information is correctly cached, and correctly timed out.)
The API is made up of a constructor, functions to set the DNS node (the domain in DNS terminology) and record type (setLabel() and setRecordType()), the corresponding getters, an isWorking() function to determine whether QDns is working or reading, a resultsReady() signal, and finally query functions for the result.
There is one query function for each RecordType, namely addresses(), mailServers(), servers(), hostNames() and texts(). There are also two generic query functions: canonicalName() return the name you'll presumably end up using (the exact meaning of that depends on the record type) and qualifiedNames() returns a list of the fully qualified names label() maps to.
See also QSocket.
None - no information. This exists only so that QDns can
have a default.
A - IPv4 addresses. By far the most common type.
Aaaa - Ipv6 addresses. So far mostly unused.
Mx - Mail eXchanger names. Used for mail delivery.
Srv - SeRVer names. Generic record type for finding
servers. So far mostly unused.
Cname - canonical name. Maps from nicknames to the true
name (the canonical name) for a host.
Ptr - name PoinTeR. Maps from IPv4 or IPv6 addresses to hostnames.
Txt - arbitrary text for domains.
We expect that some support for the RFC-2535 extensions will be added in future versions.
Constructs a DNS query object with invalid settings both for the label and the search type.
Constructs a DNS query object that will return rr information about address. The label is set to the IN-ADDR.ARPA domain name. This is useful in combination with the Ptr record type (i.e. if you want to look up a hostname for a given address).
The DNS lookup is started the next time the application enters the event loop. When the result is found the signal resultsReady() is emmitted.
rr defaults to Ptr, that maps addresses to hostnames.
Constructs a DNS query object that will return rr information about label.
The DNS lookup is started the next time the application enters the event loop. When the result is found the signal resultsReady() is emmitted.
rr defaults to A, IPv4 addresses.
[virtual]Destroys the query object and frees its allocated resources.
Returns a list of the addresses for this name if this QDns object has a recordType() of QDns::A or QDns::Aaaa and the answer is available, or an empty list else.
As a special case, if label() is a valid numeric IP address, this function returns that address.
Returns the canonical name for this DNS node. (This works regardless of what recordType() is set to.)
If the canonical name isn't known, this function returns a null string.
The canonical name of a DNS node is its full name, or the full name of the target of its CNAME. For example, if l.trolltech.com is a CNAME to lupinella.troll.no, and the search path for QDns is "trolltech.com", then the canonical name for all of "lupinella", "l", "lupinella.troll.no." and "l.trolltech.com" is "lupinella.troll.no.".
Returns a list of host names if the record type is Ptr.
Returns TRUE if QDns is doing a lookup for this object, and FALSE if this object has the information it wants.
QDns emits the resultsReady() signal when the status changes to FALSE.
Returns the domain name for which this object returns information.
See also setLabel().
Returns a list of mail servers if the record type is Mx. The struct
QDns::MailServer contains the following variables:
QString QDns::MailServer::name
Q_UINT16 QDns::MailServer::priority
Returns a list of the fully qualified names label() maps to.
Returns the record type of this query object.
See also setRecordType() and RecordType.
[signal]This signal is emitted when results are available for one of the qualifiedNames().
Returns a list of servers if the record type is Srv. The struct QDns::Server contains the following variables:
QString QDns::Server::name
Q_UINT16 QDns::Server::priority
Q_UINT16 QDns::Server::weight
Q_UINT16 QDns::Server::port
[virtual]Sets this query object to query for information about the address address. The label is set to the IN-ADDR.ARPA domain name. This is useful in combination with the Ptr record type (i.e. if you want to look up a hostname for a given address.
This does not change the recordType(), but its isWorking() most likely changes as a result.
The DNS lookup is started the next time the application enters the event loop. When the result is found the signal resultsReady() is emmitted.
[virtual]Sets this query object to query for information about label.
This does not change the recordType(), but its isWorking() most likely changes as a result.
The DNS lookup is started the next time the application enters the event loop. When the result is found the signal resultsReady() is emmitted.
Sets this object to query for rr records.
The DNS lookup is started the next time the application enters the event loop. When the result is found the signal resultsReady() is emmitted.
See also RecordType.
Returns a list of texts if the record type is Txt.
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