Rewrite client media download and support hash-based remote download

Move most of the media-related code in client.cpp into a new class
ClientMediaDownloader (clientmedia.cpp, clientmedia.h). Among other
things, this class does the following things:

- Download [remote_server][sha1] instead of [remote_server][name]. This
is to support servers that provide the same file name with different
contents.
- Initially fetch [remote_server]index.mth. This file should follow the
Minetest Hashset format (currently version 1) and contain a list of SHA1
hashes that exist on the server.
- The list of needed SHA1s is uploaded (via HTTP POST) when index.mth is
requested, so servers can optionally narrow down the list to the needs
of the client.
- If index.mth is missing (HTTP response code 404), we enter compat mode,
fetching [remote_server][name] as before this commit.
- remote_server can now contain multiple servers, separated by commas.
The downloader code attempts to split requests between the different
servers, as permitted by each server's index.mth. If one server claims
to have a file but actually doesn't (or something fails), we ask a
different server that also claims to have it.
- As before, when none of the remote servers provide a particular
file, we download it via the conventional method, i.e. using
the minetest protocol: TOSERVER_REQUEST_MEDIA / TOCLIENT_MEDIA.
- Bugfix: Every downloaded file's SHA1 is now verified against the SHA1
announced by the minetest server (before loading it and inserting it
into the file cache).
- Bugfix: Only send TOSERVER_RECEIVED_MEDIA when we actually have all
media. This should fix #863.

1 files changed, 15 insertions, 52 deletions

diff --git a/src/client.h b/src/client.h
index eb0f225a2..5969adc8e 100644
--- a/src/client.h
+++ b/src/client.h
@@ -31,32 +31,21 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "clientobject.h"
 #include "gamedef.h"
 #include "inventorymanager.h"
-#include "filecache.h"
 #include "localplayer.h"
-#include "server.h"
+#include "hud.h"
 #include "particles.h"
-#include "util/pointedthing.h"
-#include <algorithm>
 
 struct MeshMakeData;
 class MapBlockMesh;
-class IGameDef;
 class IWritableTextureSource;
 class IWritableShaderSource;
 class IWritableItemDefManager;
 class IWritableNodeDefManager;
 //class IWritableCraftDefManager;
-class ClientEnvironment;
+class ClientMediaDownloader;
 struct MapDrawControl;
 class MtEventManager;
-
-class ClientNotReadyException : public BaseException
-{
-public:
-	ClientNotReadyException(const char *s):
-		BaseException(s)
-	{}
-};
+struct PointedThing;
 
 struct QueuedMeshUpdate
 {
@@ -132,31 +121,12 @@ public:
 	IGameDef *m_gamedef;
 };
 
-class MediaFetchThread : public SimpleThread
-{
-public:
-
-	MediaFetchThread(IGameDef *gamedef):
-		m_gamedef(gamedef)
-	{
-	}
-
-	void * Thread();
-
-	std::list<MediaRequest> m_file_requests;
-	MutexedQueue<std::pair<std::string, std::string> > m_file_data;
-	std::list<MediaRequest> m_failed;
-	std::string m_remote_url;
-	IGameDef *m_gamedef;
-};
-
 enum ClientEventType
 {
 	CE_NONE,
 	CE_PLAYER_DAMAGE,
 	CE_PLAYER_FORCE_MOVE,
 	CE_DEATHSCREEN,
-	CE_TEXTURES_UPDATED,
 	CE_SHOW_FORMSPEC,
 	CE_SPAWN_PARTICLE,
 	CE_ADD_PARTICLESPAWNER,
@@ -426,19 +396,15 @@ public:
 	std::wstring accessDeniedReason()
 	{ return m_access_denied_reason; }
 
-	float mediaReceiveProgress()
-	{
-		if (!m_media_receive_started) return 0;
-		return 1.0 * m_media_received_count / m_media_count;
-	}
-
-	bool texturesReceived()
-	{ return m_media_receive_started && m_media_received_count == m_media_count; }
 	bool itemdefReceived()
 	{ return m_itemdef_received; }
 	bool nodedefReceived()
 	{ return m_nodedef_received; }
-	
+	bool mediaReceived()
+	{ return m_media_downloader == NULL; }
+
+	float mediaReceiveProgress();
+
 	void afterContentReceived(IrrlichtDevice *device, gui::IGUIFont* font);
 
 	float getRTT(void);
@@ -455,12 +421,15 @@ public:
 	virtual bool checkLocalPrivilege(const std::string &priv)
 	{ return checkPrivilege(priv); }
 
-private:
-	
+	// The following set of functions is used by ClientMediaDownloader
 	// Insert a media file appropriately into the appropriate manager
 	bool loadMedia(const std::string &data, const std::string &filename);
+	// Send a request for conventional media transfer
+	void request_media(const std::list<std::string> &file_requests);
+	// Send a notification that no conventional media transfer is needed
+	void received_media();
 
-	void request_media(const std::list<MediaRequest> &file_requests);
+private:
 
 	// Virtual methods from con::PeerHandler
 	void peerAdded(con::Peer *peer);
@@ -488,7 +457,6 @@ private:
 	MtEventManager *m_event;
 
 	MeshUpdateThread m_mesh_update_thread;
-	std::list<MediaFetchThread*> m_media_fetch_threads;
 	ClientEnvironment m_env;
 	con::Connection m_con;
 	IrrlichtDevice *m_device;
@@ -514,14 +482,9 @@ private:
 	bool m_access_denied;
 	std::wstring m_access_denied_reason;
 	Queue<ClientEvent> m_client_event_queue;
-	FileCache m_media_cache;
-	// Mapping from media file name to SHA1 checksum
-	std::map<std::string, std::string> m_media_name_sha1_map;
-	bool m_media_receive_started;
-	u32 m_media_count;
-	u32 m_media_received_count;
 	bool m_itemdef_received;
 	bool m_nodedef_received;
+	ClientMediaDownloader *m_media_downloader;
 
 	// time_of_day speed approximation for old protocol
 	bool m_time_of_day_set;