From 2424dfe007e451bb02f87884c2b272cf307d6e7c Mon Sep 17 00:00:00 2001
From: sfan5 <sfan5@live.de>
Date: Sat, 13 Jun 2020 19:03:26 +0200
Subject: Server pushing media at runtime (#9961)

---
 src/network/clientopcodes.cpp       |  2 +-
 src/network/clientpackethandler.cpp | 46 +++++++++++++++++++++++++++++++++++++
 src/network/networkprotocol.h       |  9 ++++++++
 src/network/serveropcodes.cpp       |  2 +-
 4 files changed, 57 insertions(+), 2 deletions(-)

(limited to 'src/network')

diff --git a/src/network/clientopcodes.cpp b/src/network/clientopcodes.cpp
index 0f20047c0..f812a08a1 100644
--- a/src/network/clientopcodes.cpp
+++ b/src/network/clientopcodes.cpp
@@ -68,7 +68,7 @@ const ToClientCommandHandler toClientCommandTable[TOCLIENT_NUM_MSG_TYPES] =
 	{ "TOCLIENT_TIME_OF_DAY",              TOCLIENT_STATE_CONNECTED, &Client::handleCommand_TimeOfDay }, // 0x29
 	{ "TOCLIENT_CSM_RESTRICTION_FLAGS",    TOCLIENT_STATE_CONNECTED, &Client::handleCommand_CSMRestrictionFlags }, // 0x2A
 	{ "TOCLIENT_PLAYER_SPEED",             TOCLIENT_STATE_CONNECTED, &Client::handleCommand_PlayerSpeed }, // 0x2B
-	null_command_handler,
+	{ "TOCLIENT_MEDIA_PUSH",               TOCLIENT_STATE_CONNECTED, &Client::handleCommand_MediaPush }, // 0x2C
 	null_command_handler,
 	null_command_handler,
 	{ "TOCLIENT_CHAT_MESSAGE",             TOCLIENT_STATE_CONNECTED, &Client::handleCommand_ChatMessage }, // 0x2F
diff --git a/src/network/clientpackethandler.cpp b/src/network/clientpackethandler.cpp
index e000acc92..5934eaf8c 100644
--- a/src/network/clientpackethandler.cpp
+++ b/src/network/clientpackethandler.cpp
@@ -39,6 +39,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "script/scripting_client.h"
 #include "util/serialize.h"
 #include "util/srp.h"
+#include "util/sha1.h"
 #include "tileanimation.h"
 #include "gettext.h"
 #include "skyparams.h"
@@ -1471,6 +1472,51 @@ void Client::handleCommand_PlayerSpeed(NetworkPacket *pkt)
 	player->addVelocity(added_vel);
 }
 
+void Client::handleCommand_MediaPush(NetworkPacket *pkt)
+{
+	std::string raw_hash, filename, filedata;
+	bool cached;
+
+	*pkt >> raw_hash >> filename >> cached;
+	filedata = pkt->readLongString();
+
+	if (raw_hash.size() != 20 || filedata.empty() || filename.empty() ||
+			!string_allowed(filename, TEXTURENAME_ALLOWED_CHARS)) {
+		throw PacketError("Illegal filename, data or hash");
+	}
+
+	verbosestream << "Server pushes media file \"" << filename << "\" with "
+		<< filedata.size() << " bytes of data (cached=" << cached
+		<< ")" << std::endl;
+
+	if (m_media_pushed_files.count(filename) != 0) {
+		// Silently ignore for synchronization purposes
+		return;
+	}
+
+	// Compute and check checksum of data
+	std::string computed_hash;
+	{
+		SHA1 ctx;
+		ctx.addBytes(filedata.c_str(), filedata.size());
+		unsigned char *buf = ctx.getDigest();
+		computed_hash.assign((char*) buf, 20);
+		free(buf);
+	}
+	if (raw_hash != computed_hash) {
+		verbosestream << "Hash of file data mismatches, ignoring." << std::endl;
+		return;
+	}
+
+	// Actually load media
+	loadMedia(filedata, filename, true);
+	m_media_pushed_files.insert(filename);
+
+	// Cache file for the next time when this client joins the same server
+	if (cached)
+		clientMediaUpdateCache(raw_hash, filedata);
+}
+
 /*
  * Mod channels
  */
diff --git a/src/network/networkprotocol.h b/src/network/networkprotocol.h
index ab924f1db..fd683eac9 100644
--- a/src/network/networkprotocol.h
+++ b/src/network/networkprotocol.h
@@ -323,6 +323,15 @@ enum ToClientCommand
 		v3f added_vel
 	 */
 
+	TOCLIENT_MEDIA_PUSH = 0x2C,
+	/*
+		std::string raw_hash
+		std::string filename
+		bool should_be_cached
+		u32 len
+		char filedata[len]
+	*/
+
 	// (oops, there is some gap here)
 
 	TOCLIENT_CHAT_MESSAGE = 0x2F,
diff --git a/src/network/serveropcodes.cpp b/src/network/serveropcodes.cpp
index 6ee4ff256..2fc3197c2 100644
--- a/src/network/serveropcodes.cpp
+++ b/src/network/serveropcodes.cpp
@@ -167,7 +167,7 @@ const ClientCommandFactory clientCommandFactoryTable[TOCLIENT_NUM_MSG_TYPES] =
 	{ "TOCLIENT_TIME_OF_DAY",              0, true }, // 0x29
 	{ "TOCLIENT_CSM_RESTRICTION_FLAGS",    0, true }, // 0x2A
 	{ "TOCLIENT_PLAYER_SPEED",             0, true }, // 0x2B
-	null_command_factory, // 0x2C
+	{ "TOCLIENT_MEDIA_PUSH",               0, true }, // 0x2C (sent over channel 1 too)
 	null_command_factory, // 0x2D
 	null_command_factory, // 0x2E
 	{ "TOCLIENT_CHAT_MESSAGE",             0, true }, // 0x2F
-- 
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