juce_NetworkServiceDiscovery.cpp

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 /*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
namespace juce
{
 
#if JUCE_ANDROID
 extern void acquireMulticastLock();
 extern void releaseMulticastLock();
#endif
 
NetworkServiceDiscovery::Advertiser::Advertiser (const String& serviceTypeUID,
                                                 const String& serviceDescription,
                                                 int broadcastPortToUse, int connectionPort,
                                                 RelativeTime minTimeBetweenBroadcasts)
    : Thread ("Discovery_broadcast"),
      message (serviceTypeUID), broadcastPort (broadcastPortToUse),
      minInterval (minTimeBetweenBroadcasts)
{
    message.setAttribute ("id", Uuid().toString());
    message.setAttribute ("name", serviceDescription);
    message.setAttribute ("address", String());
    message.setAttribute ("port", connectionPort);
 
    startThread (Priority::background);
}
 
NetworkServiceDiscovery::Advertiser::~Advertiser()
{
    stopThread (2000);
    socket.shutdown();
}
 
void NetworkServiceDiscovery::Advertiser::run()
{
    if (! socket.bindToPort (0))
    {
        jassertfalse;
        return;
    }
 
    while (! threadShouldExit())
    {
        sendBroadcast();
        wait ((int) minInterval.inMilliseconds());
    }
}
 
void NetworkServiceDiscovery::Advertiser::sendBroadcast()
{
    static IPAddress local = IPAddress::local();
 
    for (auto& address : IPAddress::getAllAddresses())
    {
        if (address == local)
            continue;
 
        message.setAttribute ("address", address.toString());
 
        auto broadcastAddress = IPAddress::getInterfaceBroadcastAddress (address);
        auto data = message.toString (XmlElement::TextFormat().singleLine().withoutHeader());
 
        socket.write (broadcastAddress.toString(), broadcastPort, data.toRawUTF8(), (int) data.getNumBytesAsUTF8());
    }
}
 
//==============================================================================
NetworkServiceDiscovery::AvailableServiceList::AvailableServiceList (const String& serviceType, int broadcastPort)
    : Thread ("Discovery_listen"), serviceTypeUID (serviceType)
{
   #if JUCE_ANDROID
    acquireMulticastLock();
   #endif
 
    socket.bindToPort (broadcastPort);
    startThread (Priority::background);
}
 
NetworkServiceDiscovery::AvailableServiceList::~AvailableServiceList()
{
    socket.shutdown();
    stopThread (2000);
 
    #if JUCE_ANDROID
     releaseMulticastLock();
    #endif
}
 
void NetworkServiceDiscovery::AvailableServiceList::run()
{
    while (! threadShouldExit())
    {
        if (socket.waitUntilReady (true, 200) == 1)
        {
            char buffer[1024];
            auto bytesRead = socket.read (buffer, sizeof (buffer) - 1, false);
 
            if (bytesRead > 10)
                if (auto xml = parseXML (String (CharPointer_UTF8 (buffer),
                                                 CharPointer_UTF8 (buffer + bytesRead))))
                    if (xml->hasTagName (serviceTypeUID))
                        handleMessage (*xml);
        }
 
        removeTimedOutServices();
    }
}
 
std::vector<NetworkServiceDiscovery::Service> NetworkServiceDiscovery::AvailableServiceList::getServices() const
{
    const ScopedLock sl (listLock);
    auto listCopy = services;
    return listCopy;
}
 
void NetworkServiceDiscovery::AvailableServiceList::handleAsyncUpdate()
{
    NullCheckedInvocation::invoke (onChange);
}
 
void NetworkServiceDiscovery::AvailableServiceList::handleMessage (const XmlElement& xml)
{
    Service service;
    service.instanceID = xml.getStringAttribute ("id");
 
    if (service.instanceID.trim().isNotEmpty())
    {
        service.description = xml.getStringAttribute ("name");
        service.address = IPAddress (xml.getStringAttribute ("address"));
        service.port = xml.getIntAttribute ("port");
        service.lastSeen = Time::getCurrentTime();
 
        handleMessage (service);
    }
}
 
static void sortServiceList (std::vector<NetworkServiceDiscovery::Service>& services)
{
    auto compareServices = [] (const NetworkServiceDiscovery::Service& s1,
                               const NetworkServiceDiscovery::Service& s2)
    {
        return s1.instanceID < s2.instanceID;
    };
 
    std::sort (services.begin(), services.end(), compareServices);
}
 
void NetworkServiceDiscovery::AvailableServiceList::handleMessage (const Service& service)
{
    const ScopedLock sl (listLock);
 
    for (auto& s : services)
    {
        if (s.instanceID == service.instanceID)
        {
            if (s.description != service.description
                 || s.address != service.address
                 || s.port != service.port)
            {
                s = service;
                triggerAsyncUpdate();
            }
 
            s.lastSeen = service.lastSeen;
            return;
        }
    }
 
    services.push_back (service);
    sortServiceList (services);
    triggerAsyncUpdate();
}
 
void NetworkServiceDiscovery::AvailableServiceList::removeTimedOutServices()
{
    const double timeoutSeconds = 5.0;
    auto oldestAllowedTime = Time::getCurrentTime() - RelativeTime::seconds (timeoutSeconds);
 
    const ScopedLock sl (listLock);
 
    auto oldEnd = std::end (services);
    auto newEnd = std::remove_if (std::begin (services), oldEnd,
                                  [=] (const Service& s) { return s.lastSeen < oldestAllowedTime; });
 
    if (newEnd != oldEnd)
    {
        services.erase (newEnd, oldEnd);
        triggerAsyncUpdate();
    }
}
 
} // namespace juce