Lua mod compatibility checks

[StephenCWills]

This issue intends to summarize the requirements for closing the gap between where we are and where we need to be for the 1.6 release. The goal is that it should be equally hard for someone to cheat by modding as it is by building a hacked client.

• Do not load *.lua, *.tsv, and *.sol assets in Multiplayer games unless they come from MPQ files
• Compute a "mod identifier" (SHA-256) for MPQ-packed mods
• Add "mod compatibility" information to Multiplayer save files (list of active mod identifiers)
• Do not load save files which are incompatible with the active mod configuration (mod order matters!)
• Add "mod versioning" support where mods can provide a list of mod identifiers indicating past versions they are compatible with
• Add mod compatibility checks when joining a Multiplayer game by comparing mod identifiers
• Whitelist of known good mods which can be ignored for compatibility checks (clock mod, floating numbers, etc)

[StephenCWills]

Well, here's the first snag. I compiled a list of *.tsv files that get loaded at application startup.

txtdata/text/textdat.tsv
txtdata/Experience.tsv
txtdata/classes/classdat.tsv
txtdata/classes/warrior/attributes.tsv
txtdata/classes/warrior/starting_loadout.tsv
txtdata/classes/warrior/sprites.tsv
txtdata/classes/warrior/animations.tsv
txtdata/classes/warrior/sounds.tsv
txtdata/classes/rogue/attributes.tsv
txtdata/classes/rogue/starting_loadout.tsv
txtdata/classes/rogue/sprites.tsv
txtdata/classes/rogue/animations.tsv
txtdata/classes/rogue/sounds.tsv
txtdata/classes/sorcerer/attributes.tsv
txtdata/classes/sorcerer/starting_loadout.tsv
txtdata/classes/sorcerer/sprites.tsv
txtdata/classes/sorcerer/animations.tsv
txtdata/classes/sorcerer/sounds.tsv
txtdata/classes/monk/attributes.tsv
txtdata/classes/monk/starting_loadout.tsv
txtdata/classes/monk/sprites.tsv
txtdata/classes/monk/animations.tsv
txtdata/classes/monk/sounds.tsv
txtdata/classes/bard/attributes.tsv
txtdata/classes/bard/starting_loadout.tsv
txtdata/classes/bard/sprites.tsv
txtdata/classes/bard/animations.tsv
txtdata/classes/bard/sounds.tsv
txtdata/classes/barbarian/attributes.tsv
txtdata/classes/barbarian/starting_loadout.tsv
txtdata/classes/barbarian/sprites.tsv
txtdata/classes/barbarian/animations.tsv
txtdata/classes/barbarian/sounds.tsv
txtdata/spells/spelldat.tsv
txtdata/missiles/missile_sprites.tsv
txtdata/missiles/misdat.tsv
txtdata/monsters/monstdat.tsv
txtdata/monsters/unique_monstdat.tsv
txtdata/items/itemdat.tsv
txtdata/items/unique_itemdat.tsv
txtdata/items/item_prefixes.tsv
txtdata/items/item_suffixes.tsv
txtdata/objects/objdat.tsv
txtdata/quests/questdat.tsv
txtdata/text/textdat.tsv
txtdata/Experience.tsv
txtdata/classes/classdat.tsv
txtdata/classes/warrior/attributes.tsv
txtdata/classes/warrior/starting_loadout.tsv
txtdata/classes/warrior/sprites.tsv
txtdata/classes/warrior/animations.tsv
txtdata/classes/warrior/sounds.tsv
txtdata/classes/rogue/attributes.tsv
txtdata/classes/rogue/starting_loadout.tsv
txtdata/classes/rogue/sprites.tsv
txtdata/classes/rogue/animations.tsv
txtdata/classes/rogue/sounds.tsv
txtdata/classes/sorcerer/attributes.tsv
txtdata/classes/sorcerer/starting_loadout.tsv
txtdata/classes/sorcerer/sprites.tsv
txtdata/classes/sorcerer/animations.tsv
txtdata/classes/sorcerer/sounds.tsv
txtdata/classes/monk/attributes.tsv
txtdata/classes/monk/starting_loadout.tsv
txtdata/classes/monk/sprites.tsv
txtdata/classes/monk/animations.tsv
txtdata/classes/monk/sounds.tsv
txtdata/classes/bard/attributes.tsv
txtdata/classes/bard/starting_loadout.tsv
txtdata/classes/bard/sprites.tsv
txtdata/classes/bard/animations.tsv
txtdata/classes/bard/sounds.tsv
txtdata/classes/barbarian/attributes.tsv
txtdata/classes/barbarian/starting_loadout.tsv
txtdata/classes/barbarian/sprites.tsv
txtdata/classes/barbarian/animations.tsv
txtdata/classes/barbarian/sounds.tsv
txtdata/spells/spelldat.tsv
txtdata/missiles/missile_sprites.tsv
txtdata/missiles/misdat.tsv
txtdata/monsters/monstdat.tsv
txtdata/monsters/unique_monstdat.tsv
txtdata/items/itemdat.tsv
txtdata/items/unique_itemdat.tsv
txtdata/items/item_prefixes.tsv
txtdata/items/item_suffixes.tsv
txtdata/objects/objdat.tsv
txtdata/quests/questdat.tsv

And another list of *.tsv files that get loaded when you start a Multiplayer game.

txtdata/towners/towners.tsv
txtdata/towners/quest_dialog.tsv

So a proper solution to disallow unpacked assets in Multiplayer games will need to reload all the in-memory data structures that are being populated by TSV files whenever the player enters or leaves the Multiplayer menu. And I guess all the Lua mods would need to be reloaded as well.

[StephenCWills]

Or, alternatively, I guess we could simply keep track of whether any unpacked assets were loaded and display an error when the player tries to enter the Multiplayer menu. The player would have to remove the overrides in order to play Multiplayer at all.