Build integrity + server print neo_version info

* Server now just prints neo_version on startup
* Server and client long git hashes are now matched up on startup to
  check build integrity. If they don't, the client cannot connect unless
  they have matching git hashes.
* Server convar `neo_sv_build_integrity_check` to enable/disable this
  integrity check feature. Enabled by default.
* fixes NeotokyoRebuild#437
* fixes NeotokyoRebuild#485

mp/src/game/client/CMakeLists.txt

@@ -1550,6 +1550,7 @@ target_sources_grouped(
     ${CMAKE_SOURCE_DIR}/game/shared/neo/neo_shot_manipulator.cpp
     ${CMAKE_SOURCE_DIR}/game/shared/neo/neo_shot_manipulator.h
     ${CMAKE_SOURCE_DIR}/game/shared/neo/neo_version.cpp
+    ${CMAKE_SOURCE_DIR}/game/shared/neo/neo_version.h
 )
 
 target_sources_grouped(

mp/src/game/server/CMakeLists.txt

@@ -1317,6 +1317,7 @@ target_sources_grouped(
     ${CMAKE_SOURCE_DIR}/game/shared/neo/neo_shot_manipulator.cpp
     ${CMAKE_SOURCE_DIR}/game/shared/neo/neo_shot_manipulator.h
     ${CMAKE_SOURCE_DIR}/game/shared/neo/neo_version.cpp
+    ${CMAKE_SOURCE_DIR}/game/shared/neo/neo_version.h
     neo/neo_client.cpp
     neo/neo_detpack.cpp
     neo/neo_detpack.h

mp/src/game/server/gameinterface.cpp

@@ -132,6 +132,7 @@ extern ConVar tf_mm_servermode;
 
 #ifdef NEO
 #include "neo_mount_original.h"
+#include "neo_version.h"
 #endif
 
 extern IToolFrameworkServer *g_pToolFrameworkServer;
@@ -643,6 +644,7 @@ bool CServerGameDLL::DLLInit( CreateInterfaceFn appSystemFactory,
 	{
 		return false;
 	}
+	neoVersionPrint();
 #endif
 
 	// Yes, both the client and game .dlls will try to Connect, the soundemittersystem.dll will handle this gracefully

mp/src/game/shared/neo/neo_gamerules.cpp

@@ -1,5 +1,6 @@
 #include "cbase.h"
 #include "neo_gamerules.h"
+#include "neo_version_info.h"
 #include "in_buttons.h"
 #include "ammodef.h"
 
@@ -36,6 +37,13 @@ ConVar neo_sv_player_restore("neo_sv_player_restore", "1", FCVAR_REPLICATED, "If
 ConVar neo_name("neo_name", "", FCVAR_USERINFO | FCVAR_ARCHIVE, "The nickname to set instead of the steam profile name.");
 ConVar cl_onlysteamnick("cl_onlysteamnick", "0", FCVAR_USERINFO | FCVAR_ARCHIVE, "Only show players Steam names, otherwise show player set names.", true, 0.0f, true, 1.0f);
 
+#ifdef GAME_DLL
+ConVar neo_sv_build_integrity_check("neo_sv_build_integrity_check", "1", FCVAR_GAMEDLL | FCVAR_REPLICATED,
+									"If enabled, the server checkes the build's Git hash between the client and"
+									" the server. If it doesn't match, the server rejects and disconnects the client.",
+									true, 0.0f, true, 1.0f);
+#endif
+
 REGISTER_GAMERULES_CLASS( CNEORules );
 
 BEGIN_NETWORK_TABLE_NOBASE( CNEORules, DT_NEORules )
@@ -1291,6 +1299,19 @@ void CNEORules::RestartGame()
 #ifdef GAME_DLL
 bool CNEORules::ClientConnected(edict_t *pEntity, const char *pszName, const char *pszAddress, char *reject, int maxrejectlen)
 {
+	if (neo_sv_build_integrity_check.GetBool())
+	{
+		const char *clientGitHash = engine->GetClientConVarValue(engine->IndexOfEdict(pEntity), "__neo_cl_git_hash");
+		if (V_strcmp(clientGitHash, GIT_LONGHASH))
+		{
+			// Truncate the git hash so it's short hash and doesn't make message too long
+			static constexpr int MAX_GITHASH_SHOW = 7;
+			V_snprintf(reject, maxrejectlen, "Build integrity failed! Client vs server mis-match: Check your neo_version. "
+											 "Client: %.*s | Server: %.*s",
+					   MAX_GITHASH_SHOW, clientGitHash, MAX_GITHASH_SHOW, GIT_LONGHASH);
+			return false;
+		}
+	}
 	return BaseClass::ClientConnected(pEntity, pszName, pszAddress,
 		reject, maxrejectlen);
 #if(0)

mp/src/game/shared/neo/neo_version.cpp

@@ -3,12 +3,11 @@
 #include "convar.h"
 #include "dbg.h"
 
-namespace {
-void neoVersionCallback()
+void neoVersionPrint()
 {
 #if defined(GAME_DLL)
 	static constexpr char HEADER[] = "neo_version (Server's build info):";
-#else defined(CLIENT_DLL)
+#elif defined(CLIENT_DLL)
 	static constexpr char HEADER[] = "neo_version (Client's build info):";
 #endif
 	Msg("%s\n"
@@ -25,10 +24,16 @@ void neoVersionCallback()
 		COMPILER_ID, COMPILER_VERSION);
 }
 
+namespace {
 #ifdef CLIENT_DLL
 constexpr int NEO_VERSION_FLAGS = 0;
 #else
 constexpr int NEO_VERSION_FLAGS = FCVAR_HIDDEN;
 #endif
-ConCommand neo_version("neo_version", neoVersionCallback, "Print out client/server's build's information.", NEO_VERSION_FLAGS);
+ConCommand neo_version("neo_version", neoVersionPrint, "Print out client/server's build's information.", NEO_VERSION_FLAGS);
+
+#ifdef CLIENT_DLL
+ConVar __neo_cl_git_hash("__neo_cl_git_hash", GIT_LONGHASH,
+						 FCVAR_USERINFO | FCVAR_HIDDEN | FCVAR_DONTRECORD | FCVAR_NOT_CONNECTED | FCVAR_PRINTABLEONLY);
+#endif
 }

mp/src/game/shared/neo/neo_version.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void neoVersionPrint();