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* ndns.cpp - native DNS resolution
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* Copyright (C) 2001, 2002 Justin Karneges
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//! \class NDns ndns.h
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//! \brief Simple DNS resolution using native system calls
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//! This class is to be used when Qt's QDns is not good enough. Because QDns
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//! does not use threads, it cannot make a system call asyncronously. Thus,
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//! QDns tries to imitate the behavior of each platform's native behavior, and
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//! generally falls short.
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//! NDns uses a thread to make the system call happen in the background. This
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//! gives your program native DNS behavior, at the cost of requiring threads
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//! dns.resolve("psi.affinix.com");
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//! // The class will emit the resultsReady() signal when the resolution
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//! // is finished. You may then retrieve the results:
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//! uint ip_address = dns.result();
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//! // or if you want to get the IP address as a string:
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//! QString ip_address = dns.resultString();
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#include<qapplication.h>
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#include<qsocketdevice.h>
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#include<qeventloop.h>
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#include<netinet/in.h>
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class NDnsWorkerEvent : public QCustomEvent
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enum Type { WorkerEvent = QEvent::User + 100 };
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NDnsWorkerEvent(NDnsWorker *);
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class NDnsWorker : public QThread
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NDnsWorker(QObject *, const QCString &);
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//----------------------------------------------------------------------------
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//----------------------------------------------------------------------------
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#ifndef HAVE_GETHOSTBYNAME_R
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static QMutex *workerMutex = 0;
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static QMutex *workerCancelled = 0;
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static NDnsManager *man = 0;
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bool winsock_init = false;
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class NDnsManager::Item
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class NDnsManager::Private
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Item *find(const NDns *n)
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QPtrListIterator<Item> it(list);
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for(Item *i; (i = it.current()); ++it) {
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Item *find(const NDnsWorker *w)
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QPtrListIterator<Item> it(list);
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for(Item *i; (i = it.current()); ++it) {
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NDnsManager::NDnsManager()
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#ifndef HAVE_GETHOSTBYNAME_R
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workerMutex = new QMutex;
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workerCancelled = new QMutex;
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QSocketDevice *sd = new QSocketDevice;
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d->list.setAutoDelete(true);
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connect(qApp, SIGNAL(aboutToQuit()), SLOT(app_aboutToQuit()));
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NDnsManager::~NDnsManager()
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#ifndef HAVE_GETHOSTBYNAME_R
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delete workerCancelled;
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void NDnsManager::resolve(NDns *self, const QString &name)
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i->worker = new NDnsWorker(this, name.utf8());
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void NDnsManager::stop(NDns *self)
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Item *i = d->find(self);
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#ifndef HAVE_GETHOSTBYNAME_R
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workerCancelled->lock();
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i->worker->cancelled = true;
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workerCancelled->unlock();
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bool NDnsManager::isBusy(const NDns *self) const
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Item *i = d->find(self);
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return (i ? true: false);
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bool NDnsManager::event(QEvent *e)
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if((int)e->type() == (int)NDnsWorkerEvent::WorkerEvent) {
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NDnsWorkerEvent *we = static_cast<NDnsWorkerEvent*>(e);
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we->worker->wait(); // ensure that the thread is terminated
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Item *i = d->find(we->worker);
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QHostAddress addr = i->worker->addr;
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NDns *ndns = i->ndns;
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d->list.removeRef(i);
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// nuke manager if no longer needed (code that follows MUST BE SAFE!)
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// requestor still around?
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ndns->finished(addr);
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void NDnsManager::tryDestroy()
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if(d->list.isEmpty()) {
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void NDnsManager::app_aboutToQuit()
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QEventLoop *e = qApp->eventLoop();
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e->processEvents(QEventLoop::WaitForMore);
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//----------------------------------------------------------------------------
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//----------------------------------------------------------------------------
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//! \fn void NDns::resultsReady()
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//! This signal is emitted when the DNS resolution succeeds or fails.
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//! Constructs an NDns object with parent \a parent.
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NDns::NDns(QObject *parent)
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//! Destroys the object and frees allocated resources.
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//! Resolves hostname \a host (eg. psi.affinix.com)
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void NDns::resolve(const QString &host)
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man = new NDnsManager;
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man->resolve(this, host);
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//! Cancels the lookup action.
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//! \note This will not stop the underlying system call, which must finish before the next lookup will proceed.
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//! Returns the IP address as a 32-bit integer in host-byte-order. This will be 0 if the lookup failed.
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//! \sa resultsReady()
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uint NDns::result() const
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return addr.ip4Addr();
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//! Returns the IP address as a string. This will be an empty string if the lookup failed.
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//! \sa resultsReady()
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QString NDns::resultString() const
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return addr.toString();
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//! Returns TRUE if busy resolving a hostname.
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bool NDns::isBusy() const
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return man->isBusy(this);
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void NDns::finished(const QHostAddress &a)
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//----------------------------------------------------------------------------
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//----------------------------------------------------------------------------
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NDnsWorkerEvent::NDnsWorkerEvent(NDnsWorker *p)
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:QCustomEvent(WorkerEvent)
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//----------------------------------------------------------------------------
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//----------------------------------------------------------------------------
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NDnsWorker::NDnsWorker(QObject *_par, const QCString &_host)
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success = cancelled = false;
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host = _host.copy(); // do we need this to avoid sharing across threads?
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void NDnsWorker::run()
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#ifdef HAVE_GETHOSTBYNAME_R
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gethostbyname_r(host.data(), &buf, char_buf, sizeof(char_buf), &h, &err);
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// lock for gethostbyname
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QMutexLocker locker(workerMutex);
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workerCancelled->lock();
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bool cancel = cancelled;
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workerCancelled->unlock();
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h = gethostbyname(host.data());
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QApplication::postEvent(par, new NDnsWorkerEvent(this));
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in_addr a = *((struct in_addr *)h->h_addr_list[0]);
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addr.setAddress(ntohl(a.s_addr));
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QApplication::postEvent(par, new NDnsWorkerEvent(this));
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removed
cutestuff/network/ndns.cpp
