QHostInfo¶
The QHostInfo
class provides static functions for host name lookups. More…

Synopsis¶
Functions¶
def
addresses
()def
error
()def
errorString
()def
hostName
()def
lookupId
()def
setAddresses
(addresses)def
setError
(error)def
setErrorString
(errorString)def
setHostName
(name)def
setLookupId
(id)def
swap
(other)
Static functions¶
def
abortHostLookup
(lookupId)def
fromName
(name)def
localDomainName
()def
localHostName
()
Detailed Description¶
QHostInfo
finds the IP address(es) associated with a host name, or the host name associated with an IP address. The class provides two static convenience functions: one that works asynchronously and emits a signal once the host is found, and one that blocks and returns a QHostInfo
object.
To look up a host’s IP addresses asynchronously, call lookupHost()
, which takes the host name or IP address, a receiver object, and a slot signature as arguments and returns an ID. You can abort the lookup by calling abortHostLookup()
with the lookup ID.
Example:
# To find the IP address of qt-project.org QHostInfo.lookupHost("qt-project.org", self, SLOT("printResults(QHostInfo)")) # To find the host name for 4.2.2.1 QHostInfo.lookupHost("4.2.2.1", self, SLOT("printResults(QHostInfo)"))
The slot is invoked when the results are ready. The results are stored in a QHostInfo
object. Call addresses()
to get the list of IP addresses for the host, and hostName()
to get the host name that was looked up.
If the lookup failed, error()
returns the type of error that occurred. errorString()
gives a human-readable description of the lookup error.
If you want a blocking lookup, use the fromName()
function:
info = QHostInfo.fromName("qt-project.org")
QHostInfo
supports Internationalized Domain Names (IDNs) through the IDNA and Punycode standards.
To retrieve the name of the local host, use the static function.
QHostInfo
uses the mechanisms provided by the operating system to perform the lookup. As per {https://tools.ietf.org/html/rfc6724}{RFC 6724} there is no guarantee that all IP addresses registered for a domain or host will be returned.
Note
Since Qt 4.6.1 QHostInfo
is using multiple threads for DNS lookup instead of one dedicated DNS thread. This improves performance, but also changes the order of signal emissions when using lookupHost()
compared to previous versions of Qt.
Note
Since Qt 4.6.3 QHostInfo
is using a small internal 60 second DNS cache for performance improvements.
See also
-
class
PySide6.QtNetwork.
QHostInfo
(d)¶ PySide6.QtNetwork.QHostInfo([lookupId=-1])
- Parameters
lookupId – int
Constructs an empty host info object with lookup ID id
.
See also
-
PySide6.QtNetwork.QHostInfo.
HostInfoError
¶
This enum describes the various errors that can occur when trying to resolve a host name.
Constant
Description
QHostInfo.NoError
The lookup was successful.
QHostInfo.HostNotFound
No IP addresses were found for the host.
QHostInfo.UnknownError
An unknown error occurred.
See also
-
static
PySide6.QtNetwork.QHostInfo.
abortHostLookup
(lookupId)¶ - Parameters
lookupId – int
Aborts the host lookup with the ID id
, as returned by lookupHost()
.
See also
lookupHost()
lookupId()
-
PySide6.QtNetwork.QHostInfo.
addresses
()¶ - Return type
Returns the list of IP addresses associated with hostName()
. This list may be empty.
Example:
info = QHostInfo() ... if not info.addresses().isEmpty(): address = info.addresses().first() # use the first IP addressSee also
-
PySide6.QtNetwork.QHostInfo.
error
()¶ - Return type
Returns the type of error that occurred if the host name lookup failed; otherwise returns NoError
.
See also
-
PySide6.QtNetwork.QHostInfo.
errorString
()¶ - Return type
str
If the lookup failed, this function returns a human readable description of the error; otherwise “Unknown error” is returned.
See also
-
static
PySide6.QtNetwork.QHostInfo.
fromName
(name)¶ - Parameters
name – str
- Return type
Looks up the IP address(es) for the given host name
. The function blocks during the lookup which means that execution of the program is suspended until the results of the lookup are ready. Returns the result of the lookup in a QHostInfo
object.
If you pass a literal IP address to name
instead of a host name, QHostInfo
will search for the domain name for the IP (i.e., QHostInfo
will perform a reverse lookup). On success, the returned QHostInfo
will contain both the resolved domain name and IP addresses for the host name.
See also
lookupHost()
-
PySide6.QtNetwork.QHostInfo.
hostName
()¶ - Return type
str
Returns the name of the host whose IP addresses were looked up.
See also
-
static
PySide6.QtNetwork.QHostInfo.
localDomainName
()¶ - Return type
str
-
static
PySide6.QtNetwork.QHostInfo.
localHostName
()¶ - Return type
str
-
PySide6.QtNetwork.QHostInfo.
lookupId
()¶ - Return type
int
Returns the ID of this lookup.
See also
-
PySide6.QtNetwork.QHostInfo.
setAddresses
(addresses)¶ - Parameters
addresses –
Sets the list of addresses in this QHostInfo
to addresses
.
See also
-
PySide6.QtNetwork.QHostInfo.
setError
(error)¶ - Parameters
error –
HostInfoError
Sets the error type of this QHostInfo
to error
.
See also
-
PySide6.QtNetwork.QHostInfo.
setErrorString
(errorString)¶ - Parameters
errorString – str
Sets the human readable description of the error that occurred to str
if the lookup failed.
See also
-
PySide6.QtNetwork.QHostInfo.
setHostName
(name)¶ - Parameters
name – str
Sets the host name of this QHostInfo
to hostName
.
See also
-
PySide6.QtNetwork.QHostInfo.
setLookupId
(id)¶ - Parameters
id – int
Sets the ID of this lookup to id
.
See also
lookupId()
lookupHost()
-
PySide6.QtNetwork.QHostInfo.
swap
(other)¶ - Parameters
other –
PySide6.QtNetwork.QHostInfo
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