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<title>A simple NNTP implementation</title>
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>A simple NNTP implementation</h1>
<p>
<p> This example shows how to implement your own <a href="qnetworkprotocol.html">QNetworkProtocol</a>. The
protocol that was chosen for this example is NTTP. Please note that this
implementation is very simple since it is designed to be an example. It
should not be used as a real NNTP implemention.
<p> <hr>
<p> Header file (nntp.h):
<p> <pre>/****************************************************************************
** $Id: qt/nntp.h 3.0.2 edited Oct 12 12:18 $
**
** Copyright (C) 1992-2000 Trolltech AS. All rights reserved.
**
** This file is part of an example program for Qt. This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/
#ifndef NNTP_H
#define NNTP_H
#include <<a href="qsocket-h.html">qsocket.h</a>>
#include <<a href="qnetworkprotocol-h.html">qnetworkprotocol.h</a>>
class Nntp : public <a href="qnetworkprotocol.html">QNetworkProtocol</a>
{
<a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
public:
Nntp();
virtual ~Nntp();
virtual int supportedOperations() const;
protected:
virtual void operationListChildren( <a href="qnetworkoperation.html">QNetworkOperation</a> *op );
virtual void operationGet( <a href="qnetworkoperation.html">QNetworkOperation</a> *op );
<a href="qsocket.html">QSocket</a> *commandSocket;
bool connectionReady;
bool readGroups;
bool readArticle;
private:
bool checkConnection( <a href="qnetworkoperation.html">QNetworkOperation</a> *op );
void close();
void parseGroups();
void parseArticle();
protected slots:
void hostFound();
void connected();
void closed();
void readyRead();
void error( int );
};
#endif
</pre>
<p> <hr>
<p> Implementation (nntp.cpp):
<p> <pre>/****************************************************************************
** $Id: qt/nntp.cpp 3.0.2 edited Oct 12 12:18 $
**
** Copyright (C) 1992-2000 Trolltech AS. All rights reserved.
**
** This file is part of an example program for Qt. This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/
#include "nntp.h"
#include <<a href="qurlinfo-h.html">qurlinfo.h</a>>
#include <stdlib.h>
#include <<a href="qurloperator-h.html">qurloperator.h</a>>
#include <<a href="qstringlist-h.html">qstringlist.h</a>>
#include <<a href="qregexp-h.html">qregexp.h</a>>
<a name="f297"></a>Nntp::Nntp()
: <a href="qnetworkprotocol.html">QNetworkProtocol</a>(), connectionReady( FALSE ),
readGroups( FALSE ), readArticle( FALSE )
{
// create the command socket and connect to its signals
commandSocket = new <a href="qsocket.html">QSocket</a>( this );
<a name="x950"></a> <a href="qobject.html#connect">connect</a>( commandSocket, SIGNAL( <a href="qsocket.html#hostFound">hostFound</a>() ),
this, SLOT( hostFound() ) );
<a name="x947"></a> <a href="qobject.html#connect">connect</a>( commandSocket, SIGNAL( <a href="qsocket.html#connected">connected</a>() ),
this, SLOT( connected() ) );
<a name="x948"></a> <a href="qobject.html#connect">connect</a>( commandSocket, SIGNAL( <a href="qsocket.html#connectionClosed">connectionClosed</a>() ),
this, SLOT( closed() ) );
<a name="x952"></a> <a href="qobject.html#connect">connect</a>( commandSocket, SIGNAL( <a href="qsocket.html#readyRead">readyRead</a>() ),
this, SLOT( readyRead() ) );
<a name="x949"></a> <a href="qobject.html#connect">connect</a>( commandSocket, SIGNAL( <a href="qsocket.html#error">error</a>( int ) ),
this, SLOT( error( int ) ) );
}
Nntp::~Nntp()
{
close();
delete commandSocket;
}
<a name="x941"></a>void Nntp::<a href="qnetworkprotocol.html#operationListChildren">operationListChildren</a>( <a href="qnetworkoperation.html">QNetworkOperation</a> * )
{
// create a command
<a href="qstring.html">QString</a> path = <a href="qnetworkprotocol.html#url">url</a>()->path(), cmd;
<a name="x956"></a> if ( path.<a href="qstring.html#isEmpty">isEmpty</a>() || path == "/" ) {
// if the path is empty or we are in the root dir,
// we want to read the list of available newsgroups
cmd = "list newsgroups\r\n";
} else if ( <a href="qnetworkprotocol.html#url">url</a>()->isDir() ) {
// if the path is a directory (in our case a news group)
// we want to list the articles of this group
<a name="x959"></a> path = path.<a href="qstring.html#replace">replace</a>( QRegExp( "/" ), "" );
cmd = "listgroup " + path + "\r\n";
} else
return;
// write the command to the socket
<a name="x958"></a><a name="x957"></a><a name="x954"></a> commandSocket-><a href="qsocket.html#writeBlock">writeBlock</a>( cmd.<a href="qstring.html#latin1">latin1</a>(), cmd.<a href="qstring.html#length">length</a>() );
readGroups = TRUE;
}
<a name="x940"></a>void Nntp::<a href="qnetworkprotocol.html#operationGet">operationGet</a>( <a href="qnetworkoperation.html">QNetworkOperation</a> *op )
{
// get the dirPath of the URL (this is our news group)
// and the filename (which is the article we want to read)
<a name="x938"></a> <a href="qurl.html">QUrl</a> u( op-><a href="qnetworkoperation.html#arg">arg</a>( 0 ) );
<a name="x961"></a><a name="x960"></a> <a href="qstring.html">QString</a> dirPath = u.<a href="qurl.html#dirPath">dirPath</a>(), file = u.<a href="qurl.html#fileName">fileName</a>();
dirPath = dirPath.<a href="qstring.html#replace">replace</a>( QRegExp( "/" ), "" );
// go to the group in which the article is
<a href="qstring.html">QString</a> cmd;
cmd = "group " + dirPath + "\r\n";
commandSocket-><a href="qsocket.html#writeBlock">writeBlock</a>( cmd.<a href="qstring.html#latin1">latin1</a>(), cmd.<a href="qstring.html#length">length</a>() );
// read the head of the article
cmd = "article " + file + "\r\n";
commandSocket-><a href="qsocket.html#writeBlock">writeBlock</a>( cmd.<a href="qstring.html#latin1">latin1</a>(), cmd.<a href="qstring.html#length">length</a>() );
readArticle = TRUE;
}
<a name="x939"></a>bool Nntp::<a href="qnetworkprotocol.html#checkConnection">checkConnection</a>( <a href="qnetworkoperation.html">QNetworkOperation</a> * )
{
// we are connected, return TRUE
<a name="x935"></a> if ( commandSocket-><a href="qiodevice.html#isOpen">isOpen</a>() && connectionReady )
return TRUE;
// seems that there is no chance to connect
if ( commandSocket-><a href="qiodevice.html#isOpen">isOpen</a>() )
return FALSE;
// don't call connectToHost() if we are already trying to connect
<a name="x953"></a> if ( commandSocket-><a href="qsocket.html#state">state</a>() == QSocket::Connecting )
return FALSE;
// start connecting
connectionReady = FALSE;
<a name="x946"></a> commandSocket-><a href="qsocket.html#connectToHost">connectToHost</a>( <a href="qnetworkprotocol.html#url">url</a>()->host(),
<a href="qnetworkprotocol.html#url">url</a>()->port() != -1 ? url()->port() : 119 );
return FALSE;
}
void <a name="f298"></a>Nntp::close()
{
// close the command socket
if ( commandSocket-><a href="qiodevice.html#isOpen">isOpen</a>() ) {
commandSocket-><a href="qsocket.html#writeBlock">writeBlock</a>( "quit\r\n", strlen( "quit\r\n" ) );
<a name="x945"></a> commandSocket-><a href="qsocket.html#close">close</a>();
}
}
<a name="x942"></a>int Nntp::<a href="qnetworkprotocol.html#supportedOperations">supportedOperations</a>() const
{
// we only support listing children and getting data
return OpListChildren | OpGet;
}
void <a name="f299"></a>Nntp::hostFound()
{
if ( <a href="qnetworkprotocol.html#url">url</a>() )
emit connectionStateChanged( ConHostFound, tr( "Host %1 found" ).arg( <a href="qnetworkprotocol.html#url">url</a>()->host() ) );
else
emit connectionStateChanged( ConHostFound, tr( "Host found" ) );
}
void <a name="f300"></a>Nntp::connected()
{
if ( <a href="qnetworkprotocol.html#url">url</a>() )
emit connectionStateChanged( ConConnected, tr( "Connected to host %1" ).arg( <a href="qnetworkprotocol.html#url">url</a>()->host() ) );
else
emit connectionStateChanged( ConConnected, tr( "Connected to host" ) );
}
void <a name="f301"></a>Nntp::closed()
{
if ( <a href="qnetworkprotocol.html#url">url</a>() )
emit connectionStateChanged( ConClosed, tr( "Connection to %1 closed" ).arg( <a href="qnetworkprotocol.html#url">url</a>()->host() ) );
else
emit connectionStateChanged( ConClosed, tr( "Connection closed" ) );
}
void <a name="f302"></a>Nntp::readyRead()
{
// new data arrived on the command socket
// of we should read the list of available groups, let's do so
if ( readGroups ) {
parseGroups();
return;
}
// of we should read an article, let's do so
if ( readArticle ) {
parseArticle();
return;
}
// read the new data from the socket
<a href="qcstring.html">QCString</a> s;
<a name="x943"></a><a name="x933"></a> s.<a href="qcstring.html#resize">resize</a>( commandSocket-><a href="qsocket.html#bytesAvailable">bytesAvailable</a>() );
<a name="x951"></a><a name="x937"></a> commandSocket-><a href="qsocket.html#readBlock">readBlock</a>( s.<a href="qmemarray.html#data">data</a>(), commandSocket-><a href="qsocket.html#bytesAvailable">bytesAvailable</a>() );
if ( !url() )
return;
// of the code of the server response was 200, we know that the
// server is ready to get commands from us now
<a name="x929"></a> if ( s.<a href="qcstring.html#left">left</a>( 3 ) == "200" )
connectionReady = TRUE;
}
void <a name="f303"></a>Nntp::parseGroups()
{
<a name="x944"></a> if ( !commandSocket-><a href="qsocket.html#canReadLine">canReadLine</a>() )
return;
// read one line after the other
while ( commandSocket-><a href="qsocket.html#canReadLine">canReadLine</a>() ) {
<a name="x936"></a> <a href="qstring.html">QString</a> s = commandSocket-><a href="qsocket.html#readLine">readLine</a>();
// if the line starts with a dot, all groups or articles have been listed,
// so we finished processing the listChildren() command
if ( s[ 0 ] == '.' ) {
readGroups = FALSE;
<a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>()->setState( StDone );
emit finished( <a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>() );
return;
}
// if the code of the server response is 215 or 211
// the next line will be the first group or article (depending on what we read).
// So let others know that we start reading now...
if ( s.<a href="qcstring.html#left">left</a>( 3 ) == "215" || s.<a href="qcstring.html#left">left</a>( 3 ) == "211" ) {
<a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>()->setState( StInProgress );
emit start( <a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>() );
continue;
}
// parse the line and create a QUrlInfo object
// which describes the child (group or article)
<a name="x928"></a> bool tab = s.<a href="qcstring.html#find">find</a>( '\t' ) != -1;
<a name="x931"></a> <a href="qstring.html">QString</a> group = s.<a href="qcstring.html#mid">mid</a>( 0, s.<a href="qcstring.html#find">find</a>( tab ? '\t' : ' ' ) );
<a href="qurlinfo.html">QUrlInfo</a> inf;
<a name="x965"></a> inf.<a href="qurlinfo.html#setName">setName</a>( group );
<a href="qstring.html">QString</a> path = <a href="qnetworkprotocol.html#url">url</a>()->path();
<a name="x963"></a> inf.<a href="qurlinfo.html#setDir">setDir</a>( path.<a href="qstring.html#isEmpty">isEmpty</a>() || path == "/" );
<a name="x967"></a> inf.<a href="qurlinfo.html#setSymLink">setSymLink</a>( FALSE );
<a name="x964"></a><a name="x962"></a> inf.<a href="qurlinfo.html#setFile">setFile</a>( !inf.<a href="qurlinfo.html#isDir">isDir</a>() );
<a name="x968"></a> inf.<a href="qurlinfo.html#setWritable">setWritable</a>( FALSE );
<a name="x966"></a> inf.<a href="qurlinfo.html#setReadable">setReadable</a>( TRUE );
// let others know about our new child
emit newChild( inf, operationInProgress() );
}
}
void <a name="f304"></a>Nntp::parseArticle()
{
if ( !commandSocket-><a href="qsocket.html#canReadLine">canReadLine</a>() )
return;
// read an article one line after the other
while ( commandSocket-><a href="qsocket.html#canReadLine">canReadLine</a>() ) {
<a href="qstring.html">QString</a> s = commandSocket-><a href="qsocket.html#readLine">readLine</a>();
// if the line starts with a dot, we finished reading something
if ( s[ 0 ] == '.' ) {
readArticle = FALSE;
<a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>()->setState( StDone );
emit finished( <a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>() );
return;
}
<a name="x934"></a> if ( s.<a href="qcstring.html#right">right</a>( 1 ) == "\n" )
<a name="x932"></a><a name="x930"></a> s.<a href="qcstring.html#remove">remove</a>( s.<a href="qcstring.html#length">length</a>() - 1, 1 );
// emit the new data of the article which we read
<a name="x955"></a> emit data( QCString( s.<a href="qstring.html#ascii">ascii</a>() ), operationInProgress() );
}
}
void <a name="f305"></a>Nntp::error( int code )
{
if ( code == QSocket::ErrHostNotFound ||
code == QSocket::ErrConnectionRefused ) {
// this signal is called if connecting to the server failed
if ( <a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>() ) {
<a href="qstring.html">QString</a> msg = <a href="qobject.html#tr">tr</a>( "Host not found or couldn't connect to: \n" + url()->host() );
<a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>()->setState( StFailed );
<a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>()->setProtocolDetail( msg );
<a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>()->setErrorCode( (int)ErrHostNotFound );
<a href="qnetworkprotocol.html#clearOperationQueue">clearOperationQueue</a>();
emit finished( <a href="qnetworkprotocol.html#operationInProgress">operationInProgress</a>() );
}
}
}
</pre>
<p>See also <a href="network-examples.html">Network Examples</a>.
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