add formats for state sync commands

src/CommandFormats.hh

@@ -4256,16 +4256,79 @@ struct G_Unknown_6x6A {
 } __packed__;
 
 // 6x6B: Sync enemy state (used while loading into game; same header format as 6E)
-// 6x6C: Sync object state (used while loading into game; same header format as 6E)
-// 6x6D: Sync item state (used while loading into game; same header format as 6E)
-// 6x6E: Sync flag state (used while loading into game)
 
 struct G_SyncGameStateHeader_6x6B_6x6C_6x6D_6x6E {
   G_ExtendedHeader<G_UnusedHeader> header;
-  le_uint32_t subcommand_size;
   le_uint32_t decompressed_size;
   le_uint32_t compressed_size; // Must be <= subcommand_size - 0x10
-  // BC0-compressed data follows here (use bc0_decompress from Compression.hh)
+  uint8_t data[0]; // BC0-compressed data follows here (see bc0_decompress)
+} __packed__;
+
+// Decompressed format is a list of these
+struct G_SyncEnemyState_6x6B_Entry_Decompressed {
+  le_uint32_t unknown_a1; // Possibly some kind of flags
+  // enemy_index is not the same as enemy_id, unfortunately - the enemy_id sent
+  // in the 6x76 command when an enemy is killed does not match enemy_index
+  le_uint16_t enemy_index; // FFFF = enemy is dead
+  le_uint16_t damage_taken;
+  uint8_t unknown_a4;
+  uint8_t unknown_a5;
+  uint8_t unknown_a6;
+  uint8_t unknown_a7;
+} __packed__;
+
+// 6x6C: Sync object state (used while loading into game; same header format as 6E)
+// Compressed format is the same as 6x6B.
+
+// Decompressed format is a list of these
+struct G_SyncObjectState_6x6C_Entry_Decompressed {
+  le_uint16_t flags;
+  le_uint16_t object_index;
+} __packed__;
+
+// 6x6D: Sync item state (used while loading into game; same header format as 6E)
+// Compressed format is the same as 6x6B.
+
+struct G_SyncItemState_6x6D_Decompressed {
+  // Note: 16 vs. 15 is not a bug here - there really is an extra field in the
+  // total drop count vs. the floor item count. Despite this, Pioneer 2 or Lab
+  // (area 0) isn't included in total_items_dropped_per_area (so Forest 1 is [0]
+  // in that array) but it is included in floor_item_count_per_area (so Forest 1
+  // is [1] there).
+  parray<le_uint16_t, 16> total_items_dropped_per_area;
+  // Only [0]-[3] in this array are ever actually used in normal gameplay, but
+  // the client fills in all 12 of these with reasonable values.
+  parray<le_uint32_t, 12> next_item_id_per_player;
+  parray<le_uint32_t, 15> floor_item_count_per_area;
+  struct FloorItem {
+    le_uint16_t area;
+    le_uint16_t unknown_a1;
+    le_float x;
+    le_float z;
+    le_uint16_t unknown_a2;
+    // The drop number is scoped to the area and increments by 1 each time an
+    // item is dropped. The last item dropped in each area has drop_number equal
+    // to total_items_dropped_per_area[area - 1] - 1.
+    le_uint16_t drop_number;
+    ItemData data;
+  } __packed__;
+  // Variable-length field follows:
+  // FloorItem items[sum(floor_item_count_per_area)];
+} __packed__;
+
+// 6x6E: Sync flag state (used while loading into game)
+// Compressed format is the same as 6x6B.
+
+struct G_SyncFlagState_6x6E_Decompressed {
+  // The three unknowns here are the sizes (in bytes) of three fields
+  // immediately following this structure. It is currently unknown what these
+  // fields represent. The three unknown fields always sum to the size field.
+  le_uint16_t size;
+  le_uint16_t unknown_a1;
+  le_uint16_t unknown_a2;
+  le_uint16_t unknown_a3;
+  // Three variable-length fields follow here. They are in the same order as the
+  // unknown fields above.
 } __packed__;
 
 // 6x6F: Unknown (used while loading into game)
@@ -4278,10 +4341,8 @@ struct G_Unknown_6x6F {
 // 6x70: Sync player disp data and inventory (used while loading into game)
 // Annoyingly, they didn't use the same format as the 65/67/68 commands here,
 // and instead rearranged a bunch of things.
-// TODO: Some missing fields should be easy to find in the future (e.g. when the
-// sending player doesn't have 0 meseta, for example)
 
-struct G_Unknown_6x70 {
+struct G_SyncPlayerDispAndInventory_6x70 {
   G_ExtendedHeader<G_UnusedHeader> header;
   // Offsets in this struct are relative to the overall command header
   /* 000C */ parray<le_uint16_t, 2> unknown_a1;
@@ -5101,7 +5162,7 @@ struct G_BankAction_BB_6xBD {
 } __packed__;
 
 // 6xBE: Sound chat (Episode 3; not Trial Edition)
-// This appears to be the only subcommand ever sent with the CB command.
+// This is the only subcommand ever sent with the CB command.
 
 struct G_SoundChat_GC_Ep3_6xBE {
   G_UnusedHeader header;

src/Compression.cc

@@ -602,7 +602,11 @@ string bc0_compress(
 // output pointer to any arbitrary address.
 
 string bc0_decompress(const string& data) {
-  StringReader r(data);
+  return bc0_decompress(data.data(), data.size());
+}
+
+string bc0_decompress(const void* data, size_t size) {
+  StringReader r(data, size);
   StringWriter w;
 
   // Unlike PRS, BC0 uses a memo which "rolls over" every 0x1000 bytes. The
@@ -621,7 +625,7 @@ string bc0_decompress(const string& data) {
 
   // The low byte of this value contains the control stream data; the high bits
   // specify which low bits are valid. When the last 1 is shifted out of the
-  // high bit, we need to read a new control stream byte to get the next set of
+  // high byte, we need to read a new control stream byte to get the next set of
   // control bits.
   uint16_t control_stream_bits = 0x0000;
 

src/Compression.hh

@@ -150,3 +150,4 @@ void prs_disassemble(FILE* stream, const std::string& data);
 // Compresses and decompresses data using the BC0 algorithm.
 std::string bc0_compress(const std::string& data, std::function<void(size_t, size_t)> progress_fn = nullptr);
 std::string bc0_decompress(const std::string& data);
+std::string bc0_decompress(const void* data, size_t size);

src/ReceiveSubcommands.cc

@@ -7,6 +7,7 @@
 #include <phosg/Strings.hh>
 
 #include "Client.hh"
+#include "Compression.hh"
 #include "Items.hh"
 #include "Lobby.hh"
 #include "Loggers.hh"
@@ -169,6 +170,22 @@ static void on_forward_check_game(shared_ptr<ServerState>,
   forward_subcommand(l, c, command, flag, data);
 }
 
+static void on_forward_sync_game_state(shared_ptr<ServerState>,
+    shared_ptr<Lobby> l, shared_ptr<Client> c, uint8_t command, uint8_t flag,
+    const string& data) {
+  if (!l->is_game() || !l->any_client_loading()) {
+    return;
+  }
+
+  const auto& cmd = check_size_sc<G_SyncGameStateHeader_6x6B_6x6C_6x6D_6x6E>(
+      data, sizeof(G_SyncGameStateHeader_6x6B_6x6C_6x6D_6x6E), 0xFFFF);
+  if (cmd.compressed_size > data.size() - sizeof(cmd)) {
+    throw runtime_error("compressed end offset is beyond end of command");
+  }
+
+  forward_subcommand(l, c, command, flag, data);
+}
+
 static void on_forward_check_game_loading(shared_ptr<ServerState>,
     shared_ptr<Lobby> l, shared_ptr<Client> c, uint8_t command, uint8_t flag,
     const string& data) {
@@ -1462,10 +1479,10 @@ subcommand_handler_t subcommand_handlers[0x100] = {
     /* 68 */ on_forward_check_size_game, // Telepipe/Ryuker
     /* 69 */ on_forward_check_size_game,
     /* 6A */ on_forward_check_size_game,
-    /* 6B */ on_forward_check_game_loading,
-    /* 6C */ on_forward_check_game_loading,
-    /* 6D */ on_forward_check_game_loading,
-    /* 6E */ on_forward_check_game_loading,
+    /* 6B */ on_forward_sync_game_state,
+    /* 6C */ on_forward_sync_game_state,
+    /* 6D */ on_forward_sync_game_state,
+    /* 6E */ on_forward_sync_game_state,
     /* 6F */ on_forward_check_game_loading,
     /* 70 */ on_forward_check_game_loading,
     /* 71 */ on_forward_check_game_loading,