From b0026b697a6ec898b066e7b5637dfda206511677 Mon Sep 17 00:00:00 2001
From: dP <dp@dpointer.org>
Date: Fri, 2 Apr 2021 15:51:55 +0300
Subject: [PATCH] Fix saveload format negotiation

---
 src/network/core/packet.cpp    | 15 +++++++++++++++
 src/network/core/packet.h      |  1 +
 src/network/network_server.cpp |  4 +++-
 src/saveload/saveload.cpp      |  5 +++--
 4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/network/core/packet.cpp b/src/network/core/packet.cpp
index 94ffcc5584..a7931e4c55 100644
--- a/src/network/core/packet.cpp
+++ b/src/network/core/packet.cpp
@@ -180,6 +180,21 @@ bool Packet::CanReadFromPacket(uint bytes_to_read)
 	return true;
 }
 
+/* CityMania code begin */
+bool Packet::CMCheckRead(uint bytes_to_read)
+{
+	/* Don't allow reading from a quit client/client who send bad data */
+	if (this->cs->HasClientQuit()) return false;
+
+	/* Check if variable is within packet-size */
+	if (this->pos + bytes_to_read > this->size) {
+		return false;
+	}
+
+	return true;
+}
+/* CityMania code end */
+
 /**
  * Reads the packet size from the raw packet and stores it in the packet->size
  */
diff --git a/src/network/core/packet.h b/src/network/core/packet.h
index c9be4eeb53..ec7557260b 100644
--- a/src/network/core/packet.h
+++ b/src/network/core/packet.h
@@ -75,6 +75,7 @@ public:
 	void PrepareToRead();
 
 	bool   CanReadFromPacket (uint bytes_to_read);
+	bool   CMCheckRead (uint bytes_to_read);  // CityMaina needs check that doesn't close connections
 	bool   Recv_bool  ();
 	uint8  Recv_uint8 ();
 	uint16 Recv_uint16();
diff --git a/src/network/network_server.cpp b/src/network/network_server.cpp
index 7c5f0f571a..4f4ba84e05 100644
--- a/src/network/network_server.cpp
+++ b/src/network/network_server.cpp
@@ -908,7 +908,7 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_JOIN(Packet *p)
 	p->Recv_string(name, sizeof(name));
 	playas = (Owner)p->Recv_uint8();
 	client_lang = (NetworkLanguage)p->Recv_uint8();
-	uint8 savegame_formats = p->CanReadFromPacket(1) ? p->Recv_uint8() : 23u /* assume non-modded has everything but zstd */;
+	uint8 savegame_formats = p->CMCheckRead(1) ? p->Recv_uint8() : 23u /* assume non-modded has everything but zstd */;
 
 	if (this->HasClientQuit()) return NETWORK_RECV_STATUS_CONN_LOST;
 
@@ -917,6 +917,8 @@ NetworkRecvStatus ServerNetworkGameSocketHandler::Receive_CLIENT_JOIN(Packet *p)
 	if (!preset) return this->SendError(NETWORK_ERROR_NOT_EXPECTED);
 	this->cm_preset = *preset;
 
+	DEBUG(sl, 2, "Using saveload preset '%s:%d' for client %d (mask %d)", this->cm_preset.format->name, (int)this->cm_preset.compression_level, (int)this->client_id, (int)savegame_formats);
+
 	/* join another company does not affect these values */
 	switch (playas) {
 		case COMPANY_NEW_COMPANY: // New company
diff --git a/src/saveload/saveload.cpp b/src/saveload/saveload.cpp
index 1e95d544cd..14ac722ae4 100644
--- a/src/saveload/saveload.cpp
+++ b/src/saveload/saveload.cpp
@@ -2514,11 +2514,10 @@ std::optional<SavePreset> FindCompatibleSavePreset(const std::string &server_for
  */
 uint8 GetAvailableLoadFormats()
 {
-    return 3;
     uint8 res = 0;
     for(auto &slf : _saveload_formats) {
         if (slf.init_load != nullptr) {
-            res &= (1 << slf.id);
+            res |= (1 << slf.id);
         }
     }
     return res;
@@ -2859,6 +2858,8 @@ static SaveOrLoadResult DoLoad(LoadFilter *reader, bool load_check)
 		SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, err_str);
 	}
 
+	DEBUG(sl, 2, "Using saveload format '%s'", fmt->name);
+
 	_sl.lf = fmt->init_load(_sl.lf);
 	_sl.reader = new ReadBuffer(_sl.lf);
 	_next_offs = 0;