Qt Reference Documentation

# QNetworkProxy Class Reference

The QNetworkProxy class provides a network layer proxy. More...

     #include <QNetworkProxy>

Note: All functions in this class are reentrant.

This class was introduced in Qt 4.1.

- List of all members, including inherited members

## Public Types

flags | Capabilities
enum | Capability { TunnelingCapability, ListeningCapability, UdpTunnelingCapability, CachingCapability, HostNameLookupCapability }
enum | ProxyType { NoProxy, DefaultProxy, Socks5Proxy, HttpProxy, HttpCachingProxy, FtpCachingProxy }

## Public Functions

| QNetworkProxy ()
| QNetworkProxy ( ProxyType type, const QString & hostName = QString(), quint16 port = 0, const QString & user = QString(), const QString & password = QString() )
| QNetworkProxy ( const QNetworkProxy & other )
| ~QNetworkProxy ()
Capabilities | capabilities () const
QString | hostName () const
bool | isCachingProxy () const
bool | isTransparentProxy () const
QString | password () const
quint16 | port () const
void | setCapabilities ( Capabilities capabilities )
void | setHostName ( const QString & hostName )
void | setPassword ( const QString & password )
void | setPort ( quint16 port )
void | setType ( QNetworkProxy::ProxyType type )
void | setUser ( const QString & user )
QNetworkProxy::ProxyType | type () const
QString | user () const
bool | operator!= ( const QNetworkProxy & other ) const
QNetworkProxy & | operator= ( const QNetworkProxy & other )
bool | operator== ( const QNetworkProxy & other ) const

## Static Public Members

QNetworkProxy | applicationProxy ()
void | setApplicationProxy ( const QNetworkProxy & networkProxy )

## Detailed Description

The QNetworkProxy class provides a network layer proxy.

QNetworkProxy provides the method for configuring network layer proxy support to the Qt network classes. The currently supported classes are QAbstractSocket, QTcpSocket, QUdpSocket, QTcpServer, QNetworkAccessManager and QFtp. The proxy support is designed to be as transparent as possible. This means that existing network-enabled applications that you have written should automatically support network proxy using the following code.

     QNetworkProxy proxy;
     proxy.setType(QNetworkProxy::Socks5Proxy);
     proxy.setHostName("proxy.example.com");
     proxy.setPort(1080);
     proxy.setUser("username");
     proxy.setPassword("password");
     QNetworkProxy::setApplicationProxy(proxy);

An alternative to setting an application wide proxy is to specify the proxy for individual sockets using QAbstractSocket::setProxy() and QTcpServer::setProxy(). In this way, it is possible to disable the use of a proxy for specific sockets using the following code:

     serverSocket->setProxy(QNetworkProxy::NoProxy);

Network proxy is not used if the address used in connectToHost(), bind() or listen() is equivalent to QHostAddress::LocalHost or QHostAddress::LocalHostIPv6.

Each type of proxy support has certain restrictions associated with it. You should read the ProxyType documentation carefully before selecting a proxy type to use.

Note: Changes made to currently connected sockets do not take effect. If you need to change a connected socket, you should reconnect it.

### SOCKS5

The SOCKS5 support in Qt 4 is based on RFC 1928 and RFC 1929. The supported authentication methods are no authentication and username/password authentication. Both IPv4 and IPv6 are supported. Domain names are resolved through the SOCKS5 server if the QNetworkProxy::HostNameLookupCapability is enabled, otherwise they are resolved locally and the IP address is sent to the server. There are several things to remember when using SOCKS5 with QUdpSocket and QTcpServer:

With QUdpSocket, a call to bind() may fail with a timeout error. If a port number other than 0 is passed to bind(), it is not guaranteed that it is the specified port that will be used. Use localPort() and localAddress() to get the actual address and port number in use. Because proxied UDP goes through two UDP connections, it is more likely that packets will be dropped.

With QTcpServer a call to listen() may fail with a timeout error. If a port number other than 0 is passed to listen(), then it is not guaranteed that it is the specified port that will be used. Use serverPort() and serverAddress() to get the actual address and port used to listen for connections. SOCKS5 only supports one accepted connection per call to listen(), and each call is likely to result in a different serverPort() being used.

See also QAbstractSocket and QTcpServer.

## Member Type Documentation

### enum QNetworkProxy::Capability
flags QNetworkProxy::Capabilities

These flags indicate the capabilities that a given proxy server supports.

QNetworkProxy sets different capabilities by default when the object is created (see QNetworkProxy::ProxyType for a list of the defaults). However, it is possible to change the capabitilies after the object has been created with setCapabilities().

The capabilities that QNetworkProxy supports are:

Constant | Value | Description
--- | --- | ---
`QNetworkProxy::TunnelingCapability` | `0x0001` | Ability to open transparent, tunneled TCP connections to a remote host. The proxy server relays the transmission verbatim from one side to the other and does no caching.
`QNetworkProxy::ListeningCapability` | `0x0002` | Ability to create a listening socket and wait for an incoming TCP connection from a remote host.
`QNetworkProxy::UdpTunnelingCapability` | `0x0004` | Ability to relay UDP datagrams via the proxy server to and from a remote host.
`QNetworkProxy::CachingCapability` | `0x0008` | Ability to cache the contents of the transfer. This capability is specific to each protocol and proxy type. For example, HTTP proxies can cache the contents of web data transferred with "GET" commands.
`QNetworkProxy::HostNameLookupCapability` | `0x0010` | Ability to connect to perform the lookup on a remote host name and connect to it, as opposed to requiring the application to perform the name lookup and request connection to IP addresses only.

This enum was introduced or modified in Qt 4.5.

The Capabilities type is a typedef for QFlags<Capability>. It stores an OR combination of Capability values.

### enum QNetworkProxy::ProxyType

This enum describes the types of network proxying provided in Qt.

There are two types of proxies that Qt understands: transparent proxies and caching proxies. The first group consists of proxies that can handle any arbitrary data transfer, while the second can only handle specific requests. The caching proxies only make sense for the specific classes where they can be used.

Constant | Value | Description
--- | --- | ---
`QNetworkProxy::NoProxy` | `2` | No proxying is used
`QNetworkProxy::DefaultProxy` | `0` | Proxy is determined based on the application proxy set using setApplicationProxy()
`QNetworkProxy::Socks5Proxy` | `1` | Socks5 proxying is used
`QNetworkProxy::HttpProxy` | `3` | HTTP transparent proxying is used (This value was introduced in 4.3.)
`QNetworkProxy::HttpCachingProxy` | `4` | Proxying for HTTP requests only (This value was introduced in 4.4.)
`QNetworkProxy::FtpCachingProxy` | `5` | Proxying for FTP requests only (This value was introduced in 4.4.)

The table below lists different proxy types and their capabilities. Since each proxy type has different capabilities, it is important to understand them before choosing a proxy type.

Proxy type | Description | Default capabilities
--- | --- | ---
SOCKS 5 | Generic proxy for any kind of connection. Supports TCP, UDP, binding to a port (incoming connections) and authentication. | TunnelingCapability, ListeningCapability, UdpTunnelingCapability, HostNameLookupCapability
HTTP | Implemented using the "CONNECT" command, supports only outgoing TCP connections; supports authentication. | TunnelingCapability, CachingCapability, HostNameLookupCapability
Caching-only HTTP | Implemented using normal HTTP commands, it is useful only in the context of HTTP requests (see QNetworkAccessManager) | CachingCapability, HostNameLookupCapability
Caching FTP | Implemented using an FTP proxy, it is useful only in the context of FTP requests (see QFtp, QNetworkAccessManager) | CachingCapability, HostNameLookupCapability

Also note that you shouldn't set the application default proxy (setApplicationProxy()) to a proxy that doesn't have the TunnelingCapability capability. If you do, QTcpSocket will not know how to open connections.

See also setType(), type(), capabilities(), and setCapabilities().

## Member Function Documentation

### QNetworkProxy::QNetworkProxy ()

Constructs a QNetworkProxy with DefaultProxy type; the proxy type is determined by applicationProxy(), which defaults to NoProxy.

See also setType() and setApplicationProxy().

### QNetworkProxy::QNetworkProxy ( ProxyType type, const QString & hostName = QString(), quint16 port = 0, const QString & user = QString(), const QString & password = QString() )

Constructs a QNetworkProxy with type, hostName, port, user and password.

The default capabilities for proxy type type are set automatically.

See also capabilities().

### QNetworkProxy::QNetworkProxy ( const QNetworkProxy & other )

Constructs a copy of other.

### QNetworkProxy::~QNetworkProxy ()

Destroys the QNetworkProxy object.

### QNetworkProxy QNetworkProxy::applicationProxy ()`[static]`

Returns the application level network proxying.

If a QAbstractSocket or QTcpSocket has the QNetworkProxy::DefaultProxy type, then the QNetworkProxy returned by this function is used.

See also QNetworkProxyFactory, setApplicationProxy(), QAbstractSocket::proxy(), and QTcpServer::proxy().

### Capabilities QNetworkProxy::capabilities () const

Returns the capabilities of this proxy server.

This function was introduced in Qt 4.5.

See also setCapabilities() and type().

### QString QNetworkProxy::hostName () const

Returns the host name of the proxy host.

See also setHostName(), setPort(), and port().

### bool QNetworkProxy::isCachingProxy () const

Returns true if this proxy supports the QNetworkProxy::CachingCapability capability.

In Qt 4.4, the capability was tied to the proxy type, but since Qt 4.5 it is possible to remove the capability of caching from a proxy by calling setCapabilities().

This function was introduced in Qt 4.4.

See also capabilities(), type(), and isTransparentProxy().

### bool QNetworkProxy::isTransparentProxy () const

Returns true if this proxy supports transparent tunneling of TCP connections. This matches the QNetworkProxy::TunnelingCapability capability.

In Qt 4.4, the capability was tied to the proxy type, but since Qt 4.5 it is possible to remove the capability of caching from a proxy by calling setCapabilities().

This function was introduced in Qt 4.4.

See also capabilities(), type(), and isCachingProxy().

### QString QNetworkProxy::password () const

Returns the password used for authentication.

See also user(), setPassword(), and setUser().

### quint16 QNetworkProxy::port () const

Returns the port of the proxy host.

See also setHostName(), setPort(), and hostName().

### void QNetworkProxy::setApplicationProxy ( const QNetworkProxy & networkProxy )`[static]`

Sets the application level network proxying to be networkProxy.

If a QAbstractSocket or QTcpSocket has the QNetworkProxy::DefaultProxy type, then the QNetworkProxy set with this function is used. If you want more flexibility in determining which the proxy, use the QNetworkProxyFactory class.

Setting a default proxy value with this function will override the application proxy factory set with QNetworkProxyFactory::setApplicationProxyFactory.

See also QNetworkProxyFactory, applicationProxy(), QAbstractSocket::setProxy(), and QTcpServer::setProxy().

### void QNetworkProxy::setCapabilities ( Capabilities capabilities )

Sets the capabilities of this proxy to capabilities.

This function was introduced in Qt 4.5.

See also setType() and capabilities().

### void QNetworkProxy::setHostName ( const QString & hostName )

Sets the host name of the proxy host to be hostName.

See also hostName(), setPort(), and port().

### void QNetworkProxy::setPassword ( const QString & password )

Sets the password for proxy authentication to be password.

See also user(), setUser(), and password().

### void QNetworkProxy::setPort ( quint16 port )

Sets the port of the proxy host to be port.

See also hostName(), setHostName(), and port().

### void QNetworkProxy::setType ( QNetworkProxy::ProxyType type )

Sets the proxy type for this instance to be type.

Note that changing the type of a proxy does not change the set of capabilities this QNetworkProxy object holds if any capabilities have been set with setCapabilities().

See also type() and setCapabilities().

### void QNetworkProxy::setUser ( const QString & user )

Sets the user name for proxy authentication to be user.

See also user(), setPassword(), and password().

### QNetworkProxy::ProxyType QNetworkProxy::type () const

Returns the proxy type for this instance.

See also setType().

### QString QNetworkProxy::user () const

Returns the user name used for authentication.

See also setUser(), setPassword(), and password().

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

Compares the value of this network proxy to other and returns true if they differ.

This function was introduced in Qt 4.4.

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

Assigns the value of the network proxy other to this network proxy.

This function was introduced in Qt 4.2.

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

Compares the value of this network proxy to other and returns true if they are equal (same proxy type, server as well as username and password)

This function was introduced in Qt 4.4.