db/upnp: move plugin source to upnp directory

2 files changed, 808 insertions, 0 deletions

diff --git a/src/db/plugins/upnp/UpnpDatabasePlugin.cxx b/src/db/plugins/upnp/UpnpDatabasePlugin.cxx
new file mode 100644
index 000000000..abc7638f8
--- /dev/null
+++ b/src/db/plugins/upnp/UpnpDatabasePlugin.cxx
@@ -0,0 +1,781 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "UpnpDatabasePlugin.hxx"
+#include "Directory.hxx"
+#include "Tags.hxx"
+#include "lib/upnp/Domain.hxx"
+#include "lib/upnp/ClientInit.hxx"
+#include "lib/upnp/Discovery.hxx"
+#include "lib/upnp/ContentDirectoryService.hxx"
+#include "lib/upnp/Util.hxx"
+#include "db/Interface.hxx"
+#include "db/DatabasePlugin.hxx"
+#include "db/Selection.hxx"
+#include "db/DatabaseError.hxx"
+#include "db/LightDirectory.hxx"
+#include "db/LightSong.hxx"
+#include "db/Stats.hxx"
+#include "config/ConfigData.hxx"
+#include "tag/TagBuilder.hxx"
+#include "tag/TagTable.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+#include "fs/Traits.hxx"
+#include "Log.hxx"
+#include "SongFilter.hxx"
+
+#include <string>
+#include <vector>
+#include <set>
+
+#include <assert.h>
+#include <string.h>
+
+static const char *const rootid = "0";
+
+class UpnpSong : public LightSong {
+	std::string uri2, real_uri2;
+
+	Tag tag2;
+
+public:
+	UpnpSong(UPnPDirObject &&object, std::string &&_uri)
+		:uri2(std::move(_uri)),
+		 real_uri2(std::move(object.url)),
+		 tag2(std::move(object.tag)) {
+		directory = nullptr;
+		uri = uri2.c_str();
+		real_uri = real_uri2.c_str();
+		tag = &tag2;
+		mtime = 0;
+		start_ms = end_ms = 0;
+	}
+};
+
+class UpnpDatabase : public Database {
+	UpnpClient_Handle handle;
+	UPnPDeviceDirectory *discovery;
+
+public:
+	UpnpDatabase():Database(upnp_db_plugin) {}
+
+	static Database *Create(EventLoop &loop, DatabaseListener &listener,
+				const config_param &param,
+				Error &error);
+
+	virtual bool Open(Error &error) override;
+	virtual void Close() override;
+	virtual const LightSong *GetSong(const char *uri_utf8,
+					 Error &error) const override;
+	virtual void ReturnSong(const LightSong *song) const;
+
+	virtual bool Visit(const DatabaseSelection &selection,
+			   VisitDirectory visit_directory,
+			   VisitSong visit_song,
+			   VisitPlaylist visit_playlist,
+			   Error &error) const override;
+
+	virtual bool VisitUniqueTags(const DatabaseSelection &selection,
+				     TagType tag_type,
+				     VisitString visit_string,
+				     Error &error) const override;
+
+	virtual bool GetStats(const DatabaseSelection &selection,
+			      DatabaseStats &stats,
+			      Error &error) const override;
+	virtual time_t GetUpdateStamp() const {return 0;}
+
+protected:
+	bool Configure(const config_param &param, Error &error);
+
+private:
+	bool VisitServer(const ContentDirectoryService &server,
+			 const std::list<std::string> &vpath,
+			 const DatabaseSelection &selection,
+			 VisitDirectory visit_directory,
+			 VisitSong visit_song,
+			 VisitPlaylist visit_playlist,
+			 Error &error) const;
+
+	/**
+	 * Run an UPnP search according to MPD parameters, and
+	 * visit_song the results.
+	 */
+	bool SearchSongs(const ContentDirectoryService &server,
+			 const char *objid,
+			 const DatabaseSelection &selection,
+			 VisitSong visit_song,
+			 Error &error) const;
+
+	bool SearchSongs(const ContentDirectoryService &server,
+			 const char *objid,
+			 const DatabaseSelection &selection,
+			 UPnPDirContent& dirbuf,
+			 Error &error) const;
+
+	bool Namei(const ContentDirectoryService &server,
+		   const std::list<std::string> &vpath,
+		   UPnPDirObject &dirent,
+		   Error &error) const;
+
+	/**
+	 * Take server and objid, return metadata.
+	 */
+	bool ReadNode(const ContentDirectoryService &server,
+		      const char *objid, UPnPDirObject& dirent,
+		      Error &error) const;
+
+	/**
+	 * Get the path for an object Id. This works much like pwd,
+	 * except easier cause our inodes have a parent id. Not used
+	 * any more actually (see comments in SearchSongs).
+	 */
+	bool BuildPath(const ContentDirectoryService &server,
+		       const UPnPDirObject& dirent, std::string &idpath,
+		       Error &error) const;
+};
+
+Database *
+UpnpDatabase::Create(gcc_unused EventLoop &loop,
+		     gcc_unused DatabaseListener &listener,
+		     const config_param &param, Error &error)
+{
+	UpnpDatabase *db = new UpnpDatabase();
+	if (!db->Configure(param, error)) {
+		delete db;
+		return nullptr;
+	}
+
+	/* libupnp loses its ability to receive multicast messages
+	   apparently due to daemonization; using the LazyDatabase
+	   wrapper works around this problem */
+	return db;
+}
+
+inline bool
+UpnpDatabase::Configure(const config_param &, Error &)
+{
+	return true;
+}
+
+bool
+UpnpDatabase::Open(Error &error)
+{
+	if (!UpnpClientGlobalInit(handle, error))
+		return false;
+
+	discovery = new UPnPDeviceDirectory(handle);
+	if (!discovery->Start(error)) {
+		delete discovery;
+		UpnpClientGlobalFinish();
+		return false;
+	}
+
+	return true;
+}
+
+void
+UpnpDatabase::Close()
+{
+	delete discovery;
+	UpnpClientGlobalFinish();
+}
+
+void
+UpnpDatabase::ReturnSong(const LightSong *_song) const
+{
+	assert(_song != nullptr);
+
+	UpnpSong *song = (UpnpSong *)const_cast<LightSong *>(_song);
+	delete song;
+}
+
+// Get song info by path. We can receive either the id path, or the titles
+// one
+const LightSong *
+UpnpDatabase::GetSong(const char *uri, Error &error) const
+{
+	auto vpath = stringToTokens(uri, "/", true);
+	if (vpath.size() < 2) {
+		error.Format(db_domain, DB_NOT_FOUND, "No such song: %s", uri);
+		return nullptr;
+	}
+
+	ContentDirectoryService server;
+	if (!discovery->getServer(vpath.front().c_str(), server, error))
+		return nullptr;
+
+	vpath.pop_front();
+
+	UPnPDirObject dirent;
+	if (vpath.front() != rootid) {
+		if (!Namei(server, vpath, dirent, error))
+			return nullptr;
+	} else {
+		if (!ReadNode(server, vpath.back().c_str(), dirent,
+			      error))
+			return nullptr;
+	}
+
+	return new UpnpSong(std::move(dirent), uri);
+}
+
+/**
+ * Double-quote a string, adding internal backslash escaping.
+ */
+static void
+dquote(std::string &out, const char *in)
+{
+	out.push_back('"');
+
+	for (; *in != 0; ++in) {
+		switch(*in) {
+		case '\\':
+		case '"':
+			out.push_back('\\');
+			break;
+		}
+
+		out.push_back(*in);
+	}
+
+	out.push_back('"');
+}
+
+// Run an UPnP search, according to MPD parameters. Return results as
+// UPnP items
+bool
+UpnpDatabase::SearchSongs(const ContentDirectoryService &server,
+			  const char *objid,
+			  const DatabaseSelection &selection,
+			  UPnPDirContent &dirbuf,
+			  Error &error) const
+{
+	const SongFilter *filter = selection.filter;
+	if (selection.filter == nullptr)
+		return true;
+
+	std::list<std::string> searchcaps;
+	if (!server.getSearchCapabilities(handle, searchcaps, error))
+		return false;
+
+	if (searchcaps.empty())
+		return true;
+
+	std::string cond;
+	for (const auto &item : filter->GetItems()) {
+		switch (auto tag = item.GetTag()) {
+		case LOCATE_TAG_ANY_TYPE:
+			{
+				if (!cond.empty()) {
+					cond += " and ";
+				}
+				cond += '(';
+				bool first(true);
+				for (const auto& cap : searchcaps) {
+					if (first)
+						first = false;
+					else
+						cond += " or ";
+					cond += cap;
+					if (item.GetFoldCase()) {
+						cond += " contains ";
+					} else {
+						cond += " = ";
+					}
+					dquote(cond, item.GetValue().c_str());
+				}
+				cond += ')';
+			}
+			break;
+
+		default:
+			/* Unhandled conditions like
+			   LOCATE_TAG_BASE_TYPE or
+			   LOCATE_TAG_FILE_TYPE won't have a
+			   corresponding upnp prop, so they will be
+			   skipped */
+			if (tag == TAG_ALBUM_ARTIST)
+				tag = TAG_ARTIST;
+
+			// TODO: support LOCATE_TAG_ANY_TYPE etc.
+			const char *name = tag_table_lookup(upnp_tags,
+							    TagType(tag));
+			if (name == nullptr)
+				continue;
+
+			if (!cond.empty()) {
+				cond += " and ";
+			}
+			cond += name;
+
+			/* FoldCase doubles up as contains/equal
+			   switch. UpNP search is supposed to be
+			   case-insensitive, but at least some servers
+			   have the same convention as mpd (e.g.:
+			   minidlna) */
+			if (item.GetFoldCase()) {
+				cond += " contains ";
+			} else {
+				cond += " = ";
+			}
+			dquote(cond, item.GetValue().c_str());
+		}
+	}
+
+	return server.search(handle,
+			     objid, cond.c_str(), dirbuf,
+			     error);
+}
+
+static bool
+visitSong(const UPnPDirObject &meta, const char *path,
+	  const DatabaseSelection &selection,
+	  VisitSong visit_song, Error& error)
+{
+	if (!visit_song)
+		return true;
+
+	LightSong song;
+	song.directory = nullptr;
+	song.uri = path;
+	song.real_uri = meta.url.c_str();
+	song.tag = &meta.tag;
+	song.mtime = 0;
+	song.start_ms = song.end_ms = 0;
+
+	return !selection.Match(song) || visit_song(song, error);
+}
+
+/**
+ * Build synthetic path based on object id for search results. The use
+ * of "rootid" is arbitrary, any name that is not likely to be a top
+ * directory name would fit.
+ */
+static std::string
+songPath(const std::string &servername,
+	 const std::string &objid)
+{
+	return servername + "/" + rootid + "/" + objid;
+}
+
+bool
+UpnpDatabase::SearchSongs(const ContentDirectoryService &server,
+			  const char *objid,
+			  const DatabaseSelection &selection,
+			  VisitSong visit_song,
+			  Error &error) const
+{
+	UPnPDirContent dirbuf;
+	if (!visit_song)
+		return true;
+	if (!SearchSongs(server, objid, selection, dirbuf, error))
+		return false;
+
+	for (auto &dirent : dirbuf.objects) {
+		if (dirent.type != UPnPDirObject::Type::ITEM ||
+		    dirent.item_class != UPnPDirObject::ItemClass::MUSIC)
+			continue;
+
+		// We get song ids as the result of the UPnP search. But our
+		// client expects paths (e.g. we get 1$4$3788 from minidlna,
+		// but we need to translate to /Music/All_Music/Satisfaction).
+		// We can do this in two ways:
+		//  - Rebuild a normal path using BuildPath() which is a kind of pwd
+		//  - Build a bogus path based on the song id.
+		// The first method is nice because the returned paths are pretty, but
+		// it has two big problems:
+		//  - The song paths are ambiguous: e.g. minidlna returns all search
+		//    results as being from the "All Music" directory, which can
+		//    contain several songs with the same title (but different objids)
+		//  - The performance of BuildPath() is atrocious on very big
+		//    directories, even causing timeouts in clients. And of
+		//    course, 'All Music' is very big.
+		// So we return synthetic and ugly paths based on the object id,
+		// which we later have to detect.
+		const std::string path = songPath(server.getFriendlyName(),
+						  dirent.m_id);
+		if (!visitSong(std::move(dirent), path.c_str(),
+			       selection, visit_song,
+			       error))
+			return false;
+	}
+
+	return true;
+}
+
+bool
+UpnpDatabase::ReadNode(const ContentDirectoryService &server,
+		       const char *objid, UPnPDirObject &dirent,
+		       Error &error) const
+{
+	UPnPDirContent dirbuf;
+	if (!server.getMetadata(handle, objid, dirbuf, error))
+		return false;
+
+	if (dirbuf.objects.size() == 1) {
+		dirent = std::move(dirbuf.objects.front());
+	} else {
+		error.Format(upnp_domain, "Bad resource");
+		return false;
+	}
+
+	return true;
+}
+
+bool
+UpnpDatabase::BuildPath(const ContentDirectoryService &server,
+			const UPnPDirObject& idirent,
+			std::string &path,
+			Error &error) const
+{
+	const char *pid = idirent.m_id.c_str();
+	path.clear();
+	UPnPDirObject dirent;
+	while (strcmp(pid, rootid) != 0) {
+		if (!ReadNode(server, pid, dirent, error))
+			return false;
+		pid = dirent.m_pid.c_str();
+
+		if (path.empty())
+			path = dirent.name;
+		else
+			path = PathTraitsUTF8::Build(dirent.name.c_str(),
+						     path.c_str());
+	}
+
+	path = PathTraitsUTF8::Build(server.getFriendlyName(),
+				     path.c_str());
+	return true;
+}
+
+// Take server and internal title pathname and return objid and metadata.
+bool
+UpnpDatabase::Namei(const ContentDirectoryService &server,
+		    const std::list<std::string> &vpath,
+		    UPnPDirObject &odirent,
+		    Error &error) const
+{
+	if (vpath.empty()) {
+		// looking for root info
+		if (!ReadNode(server, rootid, odirent, error))
+			return false;
+
+		return true;
+	}
+
+	std::string objid(rootid);
+
+	// Walk the path elements, read each directory and try to find the next one
+	for (auto i = vpath.begin(), last = std::prev(vpath.end());; ++i) {
+		UPnPDirContent dirbuf;
+		if (!server.readDir(handle, objid.c_str(), dirbuf, error))
+			return false;
+
+		// Look for the name in the sub-container list
+		UPnPDirObject *child = dirbuf.FindObject(i->c_str());
+		if (child == nullptr) {
+			error.Format(db_domain, DB_NOT_FOUND,
+				     "No such object");
+			return false;
+		}
+
+		if (i == last) {
+			odirent = std::move(*child);
+			return true;
+		}
+
+		if (child->type != UPnPDirObject::Type::CONTAINER) {
+			error.Format(db_domain, DB_NOT_FOUND,
+				     "Not a container");
+			return false;
+		}
+
+		objid = std::move(child->m_id);
+	}
+}
+
+static bool
+VisitItem(const UPnPDirObject &object, const char *uri,
+	  const DatabaseSelection &selection,
+	  VisitSong visit_song, VisitPlaylist visit_playlist,
+	  Error &error)
+{
+	assert(object.type == UPnPDirObject::Type::ITEM);
+
+	switch (object.item_class) {
+	case UPnPDirObject::ItemClass::MUSIC:
+		return !visit_song ||
+			visitSong(object, uri,
+				  selection, visit_song, error);
+
+	case UPnPDirObject::ItemClass::PLAYLIST:
+		if (visit_playlist) {
+			/* Note: I've yet to see a
+			   playlist item (playlists
+			   seem to be usually handled
+			   as containers, so I'll
+			   decide what to do when I
+			   see one... */
+		}
+
+		return true;
+
+	case UPnPDirObject::ItemClass::UNKNOWN:
+		return true;
+	}
+
+	assert(false);
+	gcc_unreachable();
+}
+
+static bool
+VisitObject(const UPnPDirObject &object, const char *uri,
+	    const DatabaseSelection &selection,
+	    VisitDirectory visit_directory,
+	    VisitSong visit_song,
+	    VisitPlaylist visit_playlist,
+	    Error &error)
+{
+	switch (object.type) {
+	case UPnPDirObject::Type::UNKNOWN:
+		assert(false);
+		gcc_unreachable();
+
+	case UPnPDirObject::Type::CONTAINER:
+		return !visit_directory ||
+			visit_directory(LightDirectory(uri, 0), error);
+
+	case UPnPDirObject::Type::ITEM:
+		return VisitItem(object, uri, selection,
+				 visit_song, visit_playlist,
+				 error);
+	}
+
+	assert(false);
+	gcc_unreachable();
+}
+
+// vpath is a parsed and writeable version of selection.uri. There is
+// really just one path parameter.
+bool
+UpnpDatabase::VisitServer(const ContentDirectoryService &server,
+			  const std::list<std::string> &vpath,
+			  const DatabaseSelection &selection,
+			  VisitDirectory visit_directory,
+			  VisitSong visit_song,
+			  VisitPlaylist visit_playlist,
+			  Error &error) const
+{
+	/* If the path begins with rootid, we know that this is a
+	   song, not a directory (because that's how we set things
+	   up). Just visit it. Note that the choice of rootid is
+	   arbitrary, any value not likely to be the name of a top
+	   directory would be ok. */
+	/* !Note: this *can't* be handled by Namei further down,
+	   because the path is not valid for traversal. Besides, it's
+	   just faster to access the target node directly */
+	if (!vpath.empty() && vpath.front() == rootid) {
+		switch (vpath.size()) {
+		case 1:
+			return true;
+
+		case 2:
+			break;
+
+		default:
+			error.Format(db_domain, DB_NOT_FOUND,
+				     "Not found");
+			return false;
+		}
+
+		if (visit_song) {
+			UPnPDirObject dirent;
+			if (!ReadNode(server, vpath.back().c_str(), dirent,
+				      error))
+				return false;
+
+			if (dirent.type != UPnPDirObject::Type::ITEM ||
+			    dirent.item_class != UPnPDirObject::ItemClass::MUSIC) {
+				error.Format(db_domain, DB_NOT_FOUND,
+					     "Not found");
+				return false;
+			}
+
+			std::string path = songPath(server.getFriendlyName(),
+						    dirent.m_id);
+			if (!visitSong(std::move(dirent), path.c_str(),
+				       selection,
+				       visit_song, error))
+				return false;
+		}
+		return true;
+	}
+
+	// Translate the target path into an object id and the associated metadata.
+	UPnPDirObject tdirent;
+	if (!Namei(server, vpath, tdirent, error))
+		return false;
+
+	/* If recursive is set, this is a search... No use sending it
+	   if the filter is empty. In this case, we implement limited
+	   recursion (1-deep) here, which will handle the "add dir"
+	   case. */
+	if (selection.recursive && selection.filter)
+		return SearchSongs(server, tdirent.m_id.c_str(), selection,
+				   visit_song, error);
+
+	const char *const base_uri = selection.uri.empty()
+		? server.getFriendlyName()
+		: selection.uri.c_str();
+
+	if (tdirent.type == UPnPDirObject::Type::ITEM) {
+		return VisitItem(tdirent, base_uri,
+				 selection,
+				 visit_song, visit_playlist,
+				 error);
+	}
+
+	/* Target was a a container. Visit it. We could read slices
+	   and loop here, but it's not useful as mpd will only return
+	   data to the client when we're done anyway. */
+	UPnPDirContent dirbuf;
+	if (!server.readDir(handle, tdirent.m_id.c_str(), dirbuf,
+			    error))
+		return false;
+
+	for (auto &dirent : dirbuf.objects) {
+		const std::string uri = PathTraitsUTF8::Build(base_uri,
+							      dirent.name.c_str());
+		if (!VisitObject(dirent, uri.c_str(),
+				 selection,
+				 visit_directory,
+				 visit_song, visit_playlist,
+				 error))
+			return false;
+	}
+
+	return true;
+}
+
+// Deal with the possibly multiple servers, call VisitServer if needed.
+bool
+UpnpDatabase::Visit(const DatabaseSelection &selection,
+		    VisitDirectory visit_directory,
+		    VisitSong visit_song,
+		    VisitPlaylist visit_playlist,
+		    Error &error) const
+{
+	auto vpath = stringToTokens(selection.uri, "/", true);
+	if (vpath.empty()) {
+		std::vector<ContentDirectoryService> servers;
+		if (!discovery->getDirServices(servers, error))
+			return false;
+
+		for (const auto &server : servers) {
+			if (visit_directory) {
+				const LightDirectory d(server.getFriendlyName(), 0);
+				if (!visit_directory(d, error))
+					return false;
+			}
+
+			if (selection.recursive &&
+			    !VisitServer(server, vpath, selection,
+					 visit_directory, visit_song, visit_playlist,
+					 error))
+				return false;
+		}
+
+		return true;
+	}
+
+	// We do have a path: the first element selects the server
+	std::string servername(std::move(vpath.front()));
+	vpath.pop_front();
+
+	ContentDirectoryService server;
+	if (!discovery->getServer(servername.c_str(), server, error))
+		return false;
+
+	return VisitServer(server, vpath, selection,
+			   visit_directory, visit_song, visit_playlist, error);
+}
+
+bool
+UpnpDatabase::VisitUniqueTags(const DatabaseSelection &selection,
+			      TagType tag,
+			      VisitString visit_string,
+			      Error &error) const
+{
+	if (!visit_string)
+		return true;
+
+	std::vector<ContentDirectoryService> servers;
+	if (!discovery->getDirServices(servers, error))
+		return false;
+
+	std::set<std::string> values;
+	for (auto& server : servers) {
+		UPnPDirContent dirbuf;
+		if (!SearchSongs(server, rootid, selection, dirbuf, error))
+			return false;
+
+		for (const auto &dirent : dirbuf.objects) {
+			if (dirent.type != UPnPDirObject::Type::ITEM ||
+			    dirent.item_class != UPnPDirObject::ItemClass::MUSIC)
+				continue;
+
+			const char *value = dirent.tag.GetValue(tag);
+			if (value != nullptr) {
+#if defined(__clang__) || GCC_CHECK_VERSION(4,8)
+				values.emplace(value);
+#else
+				values.insert(value);
+#endif
+			}
+		}
+	}
+
+	for (const auto& value : values)
+		if (!visit_string(value.c_str(), error))
+			return false;
+
+	return true;
+}
+
+bool
+UpnpDatabase::GetStats(const DatabaseSelection &,
+		       DatabaseStats &stats, Error &) const
+{
+	/* Note: this gets called before the daemonizing so we can't
+	   reallyopen this would be a problem if we had real stats */
+	stats.song_count = 0;
+	stats.total_duration = 0;
+	stats.artist_count = 0;
+	stats.album_count = 0;
+	return true;
+}
+
+const DatabasePlugin upnp_db_plugin = {
+	"upnp",
+	0,
+	UpnpDatabase::Create,
+};
diff --git a/src/db/plugins/upnp/UpnpDatabasePlugin.hxx b/src/db/plugins/upnp/UpnpDatabasePlugin.hxx
new file mode 100644
index 000000000..0228405cd
--- /dev/null
+++ b/src/db/plugins/upnp/UpnpDatabasePlugin.hxx
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_UPNP_DATABASE_PLUGIN_HXX
+#define MPD_UPNP_DATABASE_PLUGIN_HXX
+
+struct DatabasePlugin;
+
+extern const DatabasePlugin upnp_db_plugin;
+
+#endif