QNetworkProxyQuery Class Reference
[QtNetwork module]

Detailed Description

The QNetworkProxyQuery class is used to query the proxy settings for a socket

QNetworkProxyQuery holds the details of a socket being created or request being made. It is used by QNetworkProxy and QNetworkProxyFactory to allow applications to have a more fine-grained control over which proxy servers are used, depending on the details of the query. This allows an application to apply different settings, according to the protocol or destination hostname, for instance.

QNetworkProxyQuery supports the following criteria for selecting the proxy:

• the type of query
• the local port number to use
• the destination host name
• the destination port number
• the protocol name, such as "http" or "ftp"
• the URL being requested

The destination host name is the host in the connection in the case of outgoing connection sockets. It is the hostName parameter passed to QTcpSocket::connectToHost() or the host component of a URL requested with QNetworkRequest.

The destination port number is the requested port to connect to in the case of outgoing sockets, while the local port number is the port the socket wishes to use locally before attempting the external connection. In most cases, the local port number is used by listening sockets only (QTcpSocket) or by datagram sockets (QUdpSocket).

The protocol name is an arbitrary string that indicates the type of connection being attempted. For example, it can match the scheme of a URL, like "http", "https" and "ftp". In most cases, the proxy selection will not change depending on the protocol, but this information is provided in case a better choice can be made, like choosing an caching HTTP proxy for HTTP-based connections, but a more powerful SOCKSv5 proxy for all others.

Some of the criteria may not make sense in all of the types of query. The following table lists the criteria that are most commonly used, according to the type of query.

It should be noted that any of the criteria may be missing or unknown (an empty QString for the hostname or protocol name, -1 for the port numbers). If that happens, the functions executing the query should make their best guess or apply some implementation-defined default values.

See also QNetworkProxy, QNetworkProxyFactory, QNetworkAccessManager, and QAbstractSocket::setProxy().

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