QHostInfo

PyQt5.QtNetwork.QHostInfo

Description

The QHostInfo class provides static functions for host name lookups.

QHostInfo uses the lookup mechanisms provided by the operating system to find 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",
#                       this, SLOT(printResults(QHostInfo)));

# // To find the host name for 4.2.2.1
# QHostInfo::lookupHost("4.2.2.1",
#                       this, 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 QHostInfo::fromName() function:

# QHostInfo 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 QHostInfo::localHostName() function.

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

QAbstractSocket.

Enums

HostInfoError

This enum describes the various errors that can occur when trying to resolve a host name.

See also

error(), setError().

Member	Value	Description
HostNotFound	1	No IP addresses were found for the host.
NoError	0	The lookup was successful.
UnknownError	2	An unknown error occurred.

Methods

__init__(id: int = -1)

Constructs an empty host info object with lookup ID id.

See also

lookupId().

---

__init__(QHostInfo)

Constructs a copy of other.

---

@staticmethod
abortHostLookup(int)

Aborts the host lookup with the ID id, as returned by lookupHost().

See also

lookupHost(), lookupId().

---

addresses() → List[QHostAddress]

Returns the list of IP addresses associated with hostName(). This list may be empty.

Example:

# QHostInfo info;
# ...
# if (!info.addresses().isEmpty()) {
#     QHostAddress address = info.addresses().first();
#     // use the first IP address
# }

See also

setAddresses(), error().

---

error() → HostInfoError

Returns the type of error that occurred if the host name lookup failed; otherwise returns NoError.

See also

setError(), errorString().

---

errorString() → str

If the lookup failed, this function returns a human readable description of the error; otherwise “Unknown error” is returned.

See also

setErrorString(), error().

---

@staticmethod
fromName(str) → QHostInfo

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().

---

hostName() → str

TODO

---

@staticmethod
localDomainName() → str

TODO

---

@staticmethod
localHostName() → str

TODO

---

@staticmethod
lookupHost(str, PYQT_SLOT) → int

TODO

---

lookupId() → int

Returns the ID of this lookup.

See also

setLookupId(), abortHostLookup().

---

setAddresses(Iterable[Union[QHostAddress, SpecialAddress]])

Sets the list of addresses in this QHostInfo to addresses.

See also

addresses().

---

setError(HostInfoError)

Sets the error type of this QHostInfo to error.

See also

error(), errorString().

---

setErrorString(str)

Sets the human readable description of the error that occurred to str if the lookup failed.

See also

errorString(), setError().

---

setHostName(str)

Sets the host name of this QHostInfo to hostName.

See also

hostName().

---

setLookupId(int)

Sets the ID of this lookup to id.

See also

lookupId(), lookupHost().

---

swap(QHostInfo)

TODO