Qt 4.6: QNetworkProxyQuery Class Reference

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# QNetworkProxyQuery Class Reference
[QtNetwork module]

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

     #include <QNetworkProxyQuery>

This class was introduced in Qt 4.5.

- List of all members, including inherited members

## Public Types

enum | QueryType { TcpSocket, UdpSocket, TcpServer, UrlRequest }

## Public Functions

| QNetworkProxyQuery ()
| QNetworkProxyQuery ( const QUrl & requestUrl, QueryType queryType = UrlRequest )
| QNetworkProxyQuery ( const QString & hostname, int port, const QString & protocolTag = QString(), QueryType queryType = TcpSocket )
| QNetworkProxyQuery ( quint16 bindPort, const QString & protocolTag = QString(), QueryType queryType = TcpServer )
| QNetworkProxyQuery ( const QNetworkProxyQuery & other )
| ~QNetworkProxyQuery ()
int | localPort () const
QString | peerHostName () const
int | peerPort () const
QString | protocolTag () const
QueryType | queryType () const
void | setLocalPort ( int port )
void | setPeerHostName ( const QString & hostname )
void | setPeerPort ( int port )
void | setProtocolTag ( const QString & protocolTag )
void | setQueryType ( QueryType type )
void | setUrl ( const QUrl & url )
QUrl | url () const
bool | operator!= ( const QNetworkProxyQuery & other ) const
QNetworkProxyQuery & | operator= ( const QNetworkProxyQuery & other )
bool | operator== ( const QNetworkProxyQuery & other ) const

## 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.

Query type | Description
--- | ---
TcpSocket | Normal sockets requesting a connection to a remote server, like QTcpSocket. The peer hostname and peer port match the values passed to QTcpSocket::connectToHost(). The local port is usually -1, indicating the socket has no preference in which port should be used. The URL component is not used.
UdpSocket | Datagram-based sockets, which can both send and receive. The local port, remote host or remote port fields can all be used or be left unused, depending on the characteristics of the socket. The URL component is not used.
TcpServer | Passive server sockets that listen on a port and await incoming connections from the network. Normally, only the local port is used, but the remote address could be used in specific circumstances, for example to indicate which remote host a connection is expected from. The URL component is not used.
UrlRequest | A more high-level request, such as those coming from QNetworkAccessManager. These requests will inevitably use an outgoing TCP socket, but the this query type is provided to indicate that more detailed information is present in the URL component. For ease of implementation, the URL's host and port are set as the destination address.

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().

## Member Type Documentation

### enum QNetworkProxyQuery::QueryType

Describes the type of one QNetworkProxyQuery query.

Constant | Value | Description
--- | --- | ---
`QNetworkProxyQuery::TcpSocket` | `0` | a normal, outgoing TCP socket
`QNetworkProxyQuery::UdpSocket` | `1` | a datagram-based UDP socket, which could send to multiple destinations
`QNetworkProxyQuery::TcpServer` | `100` | a TCP server that listens for incoming connections from the network
`QNetworkProxyQuery::UrlRequest` | `101` | a more complex request which involves loading of a URL

See also queryType() and setQueryType().

## Member Function Documentation

### QNetworkProxyQuery::QNetworkProxyQuery ()

Constructs a default QNetworkProxyQuery object. By default, the query type will be QNetworkProxyQuery::TcpSocket.

### QNetworkProxyQuery::QNetworkProxyQuery ( const QUrl & requestUrl, QueryType queryType = UrlRequest )

Constructs a QNetworkProxyQuery with the URL requestUrl and sets the query type to queryType.

See also protocolTag(), peerHostName(), and peerPort().

### QNetworkProxyQuery::QNetworkProxyQuery ( const QString & hostname, int port, const QString & protocolTag = QString(), QueryType queryType = TcpSocket )

Constructs a QNetworkProxyQuery of type queryType and sets the protocol tag to be protocolTag. This constructor is suitable for QNetworkProxyQuery::TcpSocket queries, because it sets the peer hostname to hostname and the peer's port number to port.

### QNetworkProxyQuery::QNetworkProxyQuery ( quint16 bindPort, const QString & protocolTag = QString(), QueryType queryType = TcpServer )

Constructs a QNetworkProxyQuery of type queryType and sets the protocol tag to be protocolTag. This constructor is suitable for QNetworkProxyQuery::TcpSocket queries because it sets the local port number to bindPort.

Note that bindPort is of type quint16 to indicate the exact port number that is requested. The value of -1 (unknown) is not allowed in this context.

See also localPort().

### QNetworkProxyQuery::QNetworkProxyQuery ( const QNetworkProxyQuery & other )

Constructs a QNetworkProxyQuery object that is a copy of other.

### QNetworkProxyQuery::~QNetworkProxyQuery ()

Destroys this QNetworkProxyQuery object.

### int QNetworkProxyQuery::localPort () const

Returns the port number of the socket that will accept incoming packets from remote servers or -1 if the port is not known.

See also peerPort(), peerHostName(), and setLocalPort().

### QString QNetworkProxyQuery::peerHostName () const

Returns the host name or IP address being of the outgoing connection being requested, or an empty string if the remote hostname is not known.

If the query type is QNetworkProxyQuery::UrlRequest, this function returns the host component of the URL being requested.

See also peerPort(), localPort(), and setPeerHostName().

### int QNetworkProxyQuery::peerPort () const

Returns the port number for the outgoing request or -1 if the port number is not known.

If the query type is QNetworkProxyQuery::UrlRequest, this function returns the port number of the URL being requested. In general, frameworks will fill in the port number from their default values.

See also peerHostName(), localPort(), and setPeerPort().

### QString QNetworkProxyQuery::protocolTag () const

Returns the protocol tag for this QNetworkProxyQuery object, or an empty QString in case the protocol tag is unknown.

In the case of queries of type QNetworkProxyQuery::UrlRequest, this function returns the value of the scheme component of the URL.

See also setProtocolTag() and url().

### QueryType QNetworkProxyQuery::queryType () const

Returns the query type.

See also setQueryType().

### void QNetworkProxyQuery::setLocalPort ( int port )

Sets the port number that the socket wishes to use locally to accept incoming packets from remote servers to port. The local port is most often used with the QNetworkProxyQuery::TcpServer and QNetworkProxyQuery::UdpSocket query types.

Valid values are 0 to 65535 (with 0 indicating that any port number will be acceptable) or -1, which means the local port number is unknown or not applicable.

In some circumstances, for special protocols, it's the local port number can also be used with a query of type QNetworkProxyQuery::TcpSocket. When that happens, the socket is indicating it wishes to use the port number port when connecting to a remote host.

See also localPort(), setPeerPort(), and setPeerHostName().

### void QNetworkProxyQuery::setPeerHostName ( const QString & hostname )

Sets the hostname of the outgoing connection being requested to hostname. An empty hostname can be used to indicate that the remote host is unknown.

The peer host name can also be used to indicate the expected source address of an incoming connection in the case of QNetworkProxyQuery::UdpSocket or QNetworkProxyQuery::TcpServer query types.

See also peerHostName(), setPeerPort(), and setLocalPort().

### void QNetworkProxyQuery::setPeerPort ( int port )

Sets the requested port number for the outgoing connection to be port. Valid values are 1 to 65535, or -1 to indicate that the remote port number is unknown.

The peer port number can also be used to indicate the expected port number of an incoming connection in the case of QNetworkProxyQuery::UdpSocket or QNetworkProxyQuery::TcpServer query types.

See also peerPort(), setPeerHostName(), and setLocalPort().

### void QNetworkProxyQuery::setProtocolTag ( const QString & protocolTag )

Sets the protocol tag for this QNetworkProxyQuery object to be protocolTag.

The protocol tag is an arbitrary string that indicates which protocol is being talked over the socket, such as "http", "xmpp", "telnet", etc. The protocol tag is used by the backend to return a request that is more specific to the protocol in question: for example, a HTTP connection could be use a caching HTTP proxy server, while all other connections use a more powerful SOCKSv5 proxy server.

See also protocolTag().

### void QNetworkProxyQuery::setQueryType ( QueryType type )

Sets the query type of this object to be type.

See also queryType().

### void QNetworkProxyQuery::setUrl ( const QUrl & url )

Sets the URL component of this QNetworkProxyQuery object to be url. Setting the URL will also set the protocol tag, the remote host name and port number. This is done so as to facilitate the implementation of the code that determines the proxy server to be used.

See also url(), peerHostName(), and peerPort().

### QUrl QNetworkProxyQuery::url () const

Returns the URL component of this QNetworkProxyQuery object in case of a query of type QNetworkProxyQuery::UrlRequest.

See also setUrl().

### bool QNetworkProxyQuery::operator!= ( const QNetworkProxyQuery & other ) const

Returns true if this QNetworkProxyQuery object does not contain the same data as other.

### QNetworkProxyQuery & QNetworkProxyQuery::operator= ( const QNetworkProxyQuery & other )

Copies the contents of other.

### bool QNetworkProxyQuery::operator== ( const QNetworkProxyQuery & other ) const

Returns true if this QNetworkProxyQuery object contains the same data as other.