Add networking to game engine / add multiplayer chess

src/chat.c

@@ -35,6 +35,7 @@
 #include "execute.h"
 #include "file_transfers.h"
 #include "friendlist.h"
+#include "game_base.h"
 #include "help.h"
 #include "input.h"
 #include "line_info.h"
@@ -88,6 +89,7 @@ static const char *chat_cmd_list[] = {
     "/nick",
     "/note",
     "/nospam",
+    "/play",
     "/quit",
     "/savefile",
     "/sendfile",
@@ -757,6 +759,75 @@ static void chat_onConferenceInvite(ToxWindow *self, Tox *m, int32_t friendnumbe
     line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "Type \"/join\" to join the chat.");
 }
 
+void chat_onGameInvite(ToxWindow *self, Tox *m, uint32_t friend_number, const uint8_t *data, size_t length)
+{
+    if (!self || self->num != friend_number) {
+        return;
+    }
+
+    if (length < GAME_PACKET_HEADER_SIZE) {
+        return;
+    }
+
+    uint8_t version = data[0];
+
+    if (version != GAME_NETWORKING_VERSION) {
+        line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0,
+                      "Game invite failed. Friend has network protocol version %d, you have version %d.", version, GAME_NETWORKING_VERSION);
+        return;
+    }
+
+    GameType type = data[1];
+
+    if (!game_type_is_multiplayer(type)) {
+        return;
+    }
+
+    uint32_t id;
+    game_util_unpack_u32(data + 2, &id);
+
+    const char *game_string = game_get_name_string(type);
+
+    if (game_string == NULL) {
+        return;
+    }
+
+    Friends.list[friend_number].game_invite.type = type;
+    Friends.list[friend_number].game_invite.id = id;
+    Friends.list[friend_number].game_invite.pending = true;
+
+    uint32_t data_length = length - GAME_PACKET_HEADER_SIZE;
+    Friends.list[friend_number].game_invite.data_length = data_length;
+
+    if (data_length > 0) {
+        free(Friends.list[friend_number].game_invite.data);
+
+        uint8_t *buf = calloc(1, data_length);
+
+        if (buf == NULL) {
+            return;
+        }
+
+        memcpy(buf, data + GAME_PACKET_HEADER_SIZE, data_length);
+        Friends.list[friend_number].game_invite.data = buf;
+    }
+
+    char name[TOX_MAX_NAME_LENGTH];
+    get_nick_truncate(m, name, friend_number);
+
+    if (self->active_box != -1) {
+        box_notify2(self, generic_message, NT_WNDALERT_2 | user_settings->bell_on_invite, self->active_box,
+                    "invites you to play %s", game_string);
+    } else {
+        box_notify(self, generic_message, NT_WNDALERT_2 | user_settings->bell_on_invite, &self->active_box, name,
+                   "invites you to play %s", game_string);
+    }
+
+
+    line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "%s has invited you to a game of %s.", name, game_string);
+    line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "Type \"/play\" to join the game.");
+}
+
 /* AV Stuff */
 #ifdef AUDIO
 
@@ -1475,6 +1546,7 @@ ToxWindow *new_chat(Tox *m, uint32_t friendnum)
     ret->onFileControl = &chat_onFileControl;
     ret->onFileRecv = &chat_onFileRecv;
     ret->onReadReceipt = &chat_onReadReceipt;
+    ret->onGameInvite = &chat_onGameInvite;
 
 #ifdef AUDIO
     ret->onInvite = &chat_onInvite;

src/chat_commands.c

@@ -172,6 +172,59 @@ void cmd_conference_join(WINDOW *window, ToxWindow *self, Tox *m, int argc, char
 #endif
 }
 
+void cmd_game_join(WINDOW *window, ToxWindow *self, Tox *m, int argc, char (*argv)[MAX_STR_SIZE])
+{
+    UNUSED_VAR(window);
+    UNUSED_VAR(m);
+
+    bool force_small = false;
+
+    if (argc >= 2) {
+        force_small = strcasecmp(argv[2], "small") == 0;
+    }
+
+    if (!Friends.list[self->num].game_invite.pending) {
+        line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "No pending game invite.");
+        return;
+    }
+
+    if (get_num_active_windows() >= MAX_WINDOWS_NUM) {
+        line_info_add(self, false, NULL, NULL, SYS_MSG, 0, RED, " * Warning: Too many windows are open.");
+        return;
+    }
+
+    GameType type = Friends.list[self->num].game_invite.type;
+    uint32_t id = Friends.list[self->num].game_invite.id;
+    uint8_t *data = Friends.list[self->num].game_invite.data;
+    size_t length = Friends.list[self->num].game_invite.data_length;
+
+    int ret = game_initialize(self, m, type, id, data, length, force_small);
+
+    switch (ret) {
+        case 0: {
+            free(data);
+            Friends.list[self->num].game_invite.data = NULL;
+            Friends.list[self->num].game_invite.pending = false;
+            break;
+        }
+
+        case -1: {
+            line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "Window is too small. Try enlarging your window.");
+            return;
+        }
+
+        case -2: {
+            line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "Game failed to initialize (network error)");
+            return;
+        }
+
+        default: {
+            line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "Game failed to initialize (error %d)", ret);
+            return;
+        }
+    }
+}
+
 void cmd_savefile(WINDOW *window, ToxWindow *self, Tox *m, int argc, char (*argv)[MAX_STR_SIZE])
 {
     UNUSED_VAR(window);

src/chat_commands.h

@@ -29,6 +29,7 @@
 void cmd_cancelfile(WINDOW *window, ToxWindow *self, Tox *m, int argc, char (*argv)[MAX_STR_SIZE]);
 void cmd_conference_invite(WINDOW *, ToxWindow *, Tox *, int argc, char (*argv)[MAX_STR_SIZE]);
 void cmd_conference_join(WINDOW *, ToxWindow *, Tox *, int argc, char (*argv)[MAX_STR_SIZE]);
+void cmd_game_join(WINDOW *, ToxWindow *, Tox *, int argc, char (*argv)[MAX_STR_SIZE]);
 void cmd_savefile(WINDOW *, ToxWindow *, Tox *, int argc, char (*argv)[MAX_STR_SIZE]);
 void cmd_sendfile(WINDOW *, ToxWindow *, Tox *, int argc, char (*argv)[MAX_STR_SIZE]);
 

src/execute.c

@@ -81,6 +81,7 @@ static struct cmd_func chat_commands[] = {
     { "/cancel",    cmd_cancelfile        },
     { "/invite",    cmd_conference_invite },
     { "/join",      cmd_conference_join   },
+    { "/play",      cmd_game_join         },
     { "/savefile",  cmd_savefile          },
     { "/sendfile",  cmd_sendfile          },
 #ifdef AUDIO

src/friendlist.c

@@ -116,8 +116,9 @@ static void realloc_blocklist(int n)
 void kill_friendlist(ToxWindow *self)
 {
     for (size_t i = 0; i < Friends.max_idx; ++i) {
-        if (Friends.list[i].active && Friends.list[i].conference_invite.key != NULL) {
+        if (Friends.list[i].active) {
             free(Friends.list[i].conference_invite.key);
+            free(Friends.list[i].game_invite.data);
         }
     }
 
@@ -582,6 +583,34 @@ static void friendlist_add_blocked(uint32_t fnum, uint32_t bnum)
     }
 }
 
+static void friendlist_onGameInvite(ToxWindow *self, Tox *m, uint32_t friend_number, const uint8_t *data, size_t length)
+{
+    UNUSED_VAR(self);
+    UNUSED_VAR(data);
+    UNUSED_VAR(length);
+
+    if (friend_number >= Friends.max_idx) {
+        return;
+    }
+
+    if (Friends.list[friend_number].chatwin != -1) {
+        return;
+    }
+
+    if (get_num_active_windows() < MAX_WINDOWS_NUM) {
+        Friends.list[friend_number].chatwin = add_window(m, new_chat(m, Friends.list[friend_number].num));
+        return;
+    }
+
+    char nick[TOX_MAX_NAME_LENGTH];
+    get_nick_truncate(m, nick, friend_number);
+
+    line_info_add(prompt, false, NULL, NULL, SYS_MSG, 0, RED,
+                  "* Game invite from %s failed: Too many windows are open.", nick);
+
+    sound_notify(prompt, notif_error, NT_WNDALERT_1, NULL);
+}
+
 static void friendlist_onFileRecv(ToxWindow *self, Tox *m, uint32_t num, uint32_t filenum,
                                   uint64_t file_size, const char *filename, size_t name_length)
 {
@@ -1368,6 +1397,7 @@ ToxWindow *new_friendlist(void)
     ret->onStatusMessageChange = &friendlist_onStatusMessageChange;
     ret->onFileRecv = &friendlist_onFileRecv;
     ret->onConferenceInvite = &friendlist_onConferenceInvite;
+    ret->onGameInvite = &friendlist_onGameInvite;
 
 #ifdef AUDIO
     ret->onInvite = &friendlist_onAV;

src/friendlist.h

@@ -26,6 +26,7 @@
 #include <time.h>
 
 #include "file_transfers.h"
+#include "game_base.h"
 #include "toxic.h"
 #include "windows.h"
 
@@ -42,6 +43,14 @@ struct ConferenceInvite {
     bool pending;
 };
 
+struct GameInvite {
+    uint8_t *data;
+    size_t data_length;
+    GameType type;
+    uint32_t id;
+    bool pending;
+};
+
 typedef struct {
     char name[TOXIC_MAX_NAME_LENGTH + 1];
     uint16_t namelength;
@@ -58,6 +67,7 @@ typedef struct {
 
     struct LastOnline last_online;
     struct ConferenceInvite conference_invite;
+    struct GameInvite game_invite;
 
     struct FileTransfer file_receiver[MAX_FILES];
     struct FileTransfer file_sender[MAX_FILES];

src/game_base.c

@@ -25,6 +25,7 @@
 #include <string.h>
 #include <time.h>
 
+#include "friendlist.h"
 #include "game_centipede.h"
 #include "game_base.h"
 #include "game_chess.h"
@@ -32,6 +33,8 @@
 #include "line_info.h"
 #include "misc_tools.h"
 
+extern struct Winthread Winthread;
+
 /*
  * Determines the base rate at which game objects should update their state.
  * Inversely correlated with frame rate.
@@ -60,7 +63,7 @@
                                                   && ((max_x) >= (GAME_MAX_RECT_X_SMALL)))
 
 
-static ToxWindow *game_new_window(GameType type);
+static ToxWindow *game_new_window(GameType type, uint32_t friendnumber);
 
 struct GameList {
     const char *name;
@@ -74,13 +77,6 @@ static struct GameList game_list[] = {
     {  NULL,       GT_Invalid    },
 };
 
-
-static void game_get_parent_max_x_y(const ToxWindow *parent, int *max_x, int *max_y)
-{
-    getmaxyx(parent->window, *max_y, *max_x);
-    *max_y -= (CHATBOX_HEIGHT + WINDOW_BAR_HEIGHT);
-}
-
 /*
  * Returns the GameType associated with `game_string`.
  */
@@ -97,8 +93,7 @@ GameType game_get_type(const char *game_string)
     return GT_Invalid;
 }
 
-/* Returns the string name associated with `type`. */
+const char *game_get_name_string(GameType type)
-static const char *game_get_name_string(GameType type)
 {
     GameType match_type;
 
@@ -111,9 +106,6 @@ static const char *game_get_name_string(GameType type)
     return NULL;
 }
 
-/*
- * Prints all available games to window associated with `self`.
- */
 void game_list_print(ToxWindow *self)
 {
     line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "Available games:");
@@ -125,11 +117,16 @@ void game_list_print(ToxWindow *self)
     }
 }
 
+bool game_type_is_multiplayer(GameType type)
+{
+    return type == GT_Chess;
+}
+
 /* Returns the current wall time in milliseconds */
 TIME_MS get_time_millis(void)
 {
     struct timespec t;
-    timespec_get(&t, TIME_UTC);
+    clock_gettime(CLOCK_MONOTONIC, &t);
     return ((TIME_MS) t.tv_sec) * 1000 + ((TIME_MS) t.tv_nsec) / 1000000;
 }
 
@@ -164,9 +161,9 @@ static void game_toggle_pause(GameData *game)
     }
 }
 
-static int game_initialize_type(GameData *game)
+static int game_initialize_type(GameData *game, const uint8_t *data, size_t length)
 {
-    int ret = -1;
+    int ret = -3;
 
     switch (game->type) {
         case GT_Snake: {
@@ -180,7 +177,7 @@ static int game_initialize_type(GameData *game)
         }
 
         case GT_Chess: {
-            ret = chess_initialize(game);
+            ret = chess_initialize(game, data, length);
             break;
         }
 
@@ -192,18 +189,14 @@ static int game_initialize_type(GameData *game)
     return ret;
 }
 
-/*
+int game_initialize(const ToxWindow *parent, Tox *m, GameType type, uint32_t id, const uint8_t *multiplayer_data,
- * Initializes game instance.
+                    size_t length, bool force_small_window)
- *
- * Return 0 on success.
- * Return -1 if screen is too small.
- * Return -2 on other failure.
- */
-int game_initialize(const ToxWindow *parent, Tox *m, GameType type, bool force_small_window)
 {
     int max_x;
     int max_y;
-    game_get_parent_max_x_y(parent, &max_x, &max_y);
+    getmaxyx(parent->window, max_y, max_x);
+
+    max_y -= (CHATBOX_HEIGHT + WINDOW_BAR_HEIGHT);
 
     int max_game_window_x = GAME_MAX_SQUARE_X;
     int max_game_window_y = GAME_MAX_SQUARE_Y;
@@ -221,10 +214,10 @@ int game_initialize(const ToxWindow *parent, Tox *m, GameType type, bool force_s
         }
     }
 
-    ToxWindow *self = game_new_window(type);
+    ToxWindow *self = game_new_window(type, parent->num);
 
     if (self == NULL) {
-        return -2;
+        return -4;
     }
 
     GameData *game = self->game;
@@ -234,27 +227,47 @@ int game_initialize(const ToxWindow *parent, Tox *m, GameType type, bool force_s
     if (window_id == -1) {
         free(game);
         free(self);
+        return -4;
+    }
+
+    game->is_multiplayer = game_type_is_multiplayer(type);
+
+    if (game->is_multiplayer) {
+        if (parent->type != WINDOW_TYPE_CHAT) {
+            game_kill(self);
+            return -3;
+        }
+
+        if (get_friend_connection_status(parent->num) == TOX_CONNECTION_NONE) {
             return -2;
         }
 
-    game->parent = parent;
+        game->is_multiplayer = true;
+    }
+
+    game->tox = m;
     game->window_shape = GW_ShapeSquare;
     game->game_max_x = max_game_window_x;
     game->game_max_y = max_game_window_y;
+    game->parent_max_x = max_x;
+    game->parent_max_y = max_y;
     game->update_interval = GAME_DEFAULT_UPDATE_INTERVAL;
     game->type = type;
     game->window_id = window_id;
-    game->level = 0;
     game->window = subwin(self->window, max_y, max_x, 0, 0);
+    game->id = id;
+    game->friend_number = parent->num;
 
     if (game->window == NULL) {
         game_kill(self);
-        return -2;
+        return -4;
     }
 
-    if (game_initialize_type(game) == -1) {
+    int init_ret = game_initialize_type(game, multiplayer_data, length);
+
+    if (init_ret < 0) {
         game_kill(self);
-        return -1;
+        return init_ret;
     }
 
     game->status = GS_Running;
@@ -283,11 +296,8 @@ int game_set_window_shape(GameData *game, GameWindowShape shape)
         return 0;
     }
 
-    const ToxWindow *parent = game->parent;
+    const int max_x = game->parent_max_x;
-
+    const int max_y = game->parent_max_y;
-    int max_x;
-    int max_y;
-    game_get_parent_max_x_y(parent, &max_x, &max_y);
 
     if (WINDOW_SIZE_LARGE_RECT_VALID(max_x, max_y)) {
         game->game_max_x = GAME_MAX_RECT_X;
@@ -439,14 +449,14 @@ static int game_restart(GameData *game)
 
     game_clear_all_messages(game);
 
-    if (game_initialize_type(game) == -1) {
+    if (game_initialize_type(game, NULL, 0) == -1) {
         return -1;
     }
 
     return 0;
 }
 
-static void game_draw_help_bar(WINDOW *win)
+static void game_draw_help_bar(const GameData *game, WINDOW *win)
 {
     int max_x;
     int max_y;
@@ -456,10 +466,12 @@ static void game_draw_help_bar(WINDOW *win)
 
     wmove(win, max_y - 1, 1);
 
+    if (!game->is_multiplayer) {
         wprintw(win, "Pause: ");
         wattron(win, A_BOLD);
         wprintw(win, "F2  ");
         wattroff(win, A_BOLD);
+    }
 
     wprintw(win, "Quit: ");
     wattron(win, A_BOLD);
@@ -628,13 +640,13 @@ void game_onDraw(ToxWindow *self, Tox *m)
 {
     UNUSED_VAR(m);   // Note: This function is not thread safe if we ever need to use `m`
 
-    game_draw_help_bar(self->window);
+    GameData *game = self->game;
+
+    game_draw_help_bar(game, self->window);
     draw_window_bar(self);
 
     curs_set(0);
 
-    GameData *game = self->game;
-
     int max_x;
     int max_y;
     getmaxyx(game->window, max_y, max_x);
@@ -678,8 +690,8 @@ void game_onDraw(ToxWindow *self, Tox *m)
 
 bool game_onKey(ToxWindow *self, Tox *m, wint_t key, bool is_printable)
 {
-    UNUSED_VAR(m);  // Note: this function is not thread safe if we ever need to use `m`
     UNUSED_VAR(is_printable);
+    UNUSED_VAR(m);
 
     GameData *game = self->game;
 
@@ -688,12 +700,12 @@ bool game_onKey(ToxWindow *self, Tox *m, wint_t key, bool is_printable)
         return true;
     }
 
-    if (key == KEY_F(2)) {
+    if (!game->is_multiplayer && key == KEY_F(2)) {
         game_toggle_pause(self->game);
         return true;
     }
 
-    if (game->status == GS_Finished && key == KEY_F(5)) {
+    if (!game->is_multiplayer && game->status == GS_Finished && key == KEY_F(5)) {
         if (game_restart(self->game) == -1) {
             fprintf(stderr, "Warning: game_restart() failed\n");
         }
@@ -702,7 +714,15 @@ bool game_onKey(ToxWindow *self, Tox *m, wint_t key, bool is_printable)
     }
 
     if (game->cb_game_key_press) {
+        if (game->is_multiplayer) {
+            pthread_mutex_lock(&Winthread.lock);  // we use the tox instance when we send packets
+        }
+
         game->cb_game_key_press(game, key, game->cb_game_key_press_data);
+
+        if (game->is_multiplayer) {
+            pthread_mutex_unlock(&Winthread.lock);
+        }
     }
 
     return true;
@@ -723,7 +743,55 @@ void game_onInit(ToxWindow *self, Tox *m)
     self->window_bar = subwin(self->window, WINDOW_BAR_HEIGHT, max_x, max_y - 2, 0);
 }
 
-static ToxWindow *game_new_window(GameType type)
+/*
+ * Byte 0:   Game type
+ * Byte 1-4: Game ID
+ * Byte 5-*  Game data
+ */
+void game_onPacket(ToxWindow *self, Tox *m, uint32_t friendnumber, const uint8_t *data, size_t length)
+{
+    UNUSED_VAR(m);
+
+    GameData *game = self->game;
+
+    if (friendnumber != self->num) {
+        return;
+    }
+
+    if (data == NULL) {
+        return;
+    }
+
+    if (length < GAME_PACKET_HEADER_SIZE || length > GAME_MAX_PACKET_SIZE) {
+        return;
+    }
+
+    if (data[0] != GAME_NETWORKING_VERSION) {
+        return;
+    }
+
+    GameType type = (GameType)data[1];
+
+    if (game->type != type) {
+        return;
+    }
+
+    uint32_t id;
+    game_util_unpack_u32(data + 2, &id);
+
+    if (game->id != id) {
+        return;
+    }
+
+    data += GAME_PACKET_HEADER_SIZE;
+    length -= GAME_PACKET_HEADER_SIZE;
+
+    if (game->cb_game_on_packet) {
+        game->cb_game_on_packet(game, data, length, game->cb_game_on_packet_data);
+    }
+}
+
+static ToxWindow *game_new_window(GameType type, uint32_t friendnumber)
 {
     const char *window_name = game_get_name_string(type);
 
@@ -737,11 +805,13 @@ static ToxWindow *game_new_window(GameType type)
         return NULL;
     }
 
+    ret->num = friendnumber;
     ret->type = WINDOW_TYPE_GAME;
 
     ret->onInit = &game_onInit;
     ret->onDraw = &game_onDraw;
     ret->onKey = &game_onKey;
+    ret->onGameData = &game_onPacket;
 
     ret->game = calloc(1, sizeof(GameData));
 
@@ -941,3 +1011,58 @@ void game_set_cb_on_pause(GameData *game, cb_game_pause *func, void *cb_data)
     game->cb_game_pause_data = cb_data;
 }
 
+void game_set_cb_on_packet(GameData *game, cb_game_on_packet *func, void *cb_data)
+{
+    game->cb_game_on_packet = func;
+    game->cb_game_on_packet_data = cb_data;
+}
+
+/*
+ * Wraps `packet` in a header comprised of the custom packet type, game type and game id.
+ */
+static int game_wrap_packet(const GameData *game, uint8_t *packet, size_t size, GamePacketType packet_type)
+{
+    if (size < GAME_PACKET_HEADER_SIZE + 1) {
+        return -1;
+    }
+
+    if (packet_type != GP_Invite && packet_type != GP_Data) {
+        return -1;
+    }
+
+    packet[0] = packet_type == GP_Data ? CUSTOM_PACKET_GAME_DATA : CUSTOM_PACKET_GAME_INVITE;
+    packet[1] = GAME_NETWORKING_VERSION;
+    packet[2] = game->type;
+
+    game_util_pack_u32(packet + 3, game->id);
+
+    return 0;
+}
+
+int game_send_packet(const GameData *game, const uint8_t *data, size_t length, GamePacketType packet_type)
+{
+    if (length > GAME_MAX_DATA_SIZE) {
+        return -1;
+    }
+
+    uint8_t packet[GAME_MAX_PACKET_SIZE];
+
+    if (game_wrap_packet(game, packet, sizeof(packet), packet_type) == -1) {
+        return -1;
+    }
+
+    size_t packet_length = 1 + GAME_PACKET_HEADER_SIZE;  // 1 extra byte for custom packet type
+
+    memcpy(packet + 1 + GAME_PACKET_HEADER_SIZE, data, length);
+    packet_length += length;
+
+    TOX_ERR_FRIEND_CUSTOM_PACKET err;
+
+    if (!tox_friend_send_lossless_packet(game->tox, game->friend_number, packet, packet_length, &err)) {
+        fprintf(stderr, "failed to send game packet: error %d\n", err);
+        return -1;
+    }
+
+    return -0;
+}
+

src/game_base.h

@@ -52,14 +52,35 @@
 /* Maximum length of a game message set with game_set_message() */
 #define GAME_MAX_MESSAGE_SIZE 64
 
+/* Default number of seconds a game message is displayed for */
 #define GAME_MESSAGE_DEFAULT_TIMEOUT 3
 
+
+/***** NETWORKING DEFINES *****/
+
+/* Header starts after custom packet type byte. Comprised of: NetworkVersion (1b) + GameType (1b) + id (4b) */
+#define GAME_PACKET_HEADER_SIZE (1 + 1 + sizeof(uint32_t))
+
+/* Max size of a game packet including the header */
+#define GAME_MAX_PACKET_SIZE 1024
+
+/* Max size of a game packet payload */
+#define GAME_MAX_DATA_SIZE (GAME_MAX_PACKET_SIZE - GAME_PACKET_HEADER_SIZE - 1)
+
+/* Current version of networking protocol */
+#define GAME_NETWORKING_VERSION 0x01
+
 typedef void cb_game_update_state(GameData *game, void *cb_data);
 typedef void cb_game_render_window(GameData *game, WINDOW *window, void *cb_data);
 typedef void cb_game_kill(GameData *game, void *cb_data);
 typedef void cb_game_pause(GameData *game, bool is_paused, void *cb_data);
 typedef void cb_game_key_press(GameData *game, int key, void *cb_data);
+typedef void cb_game_on_packet(GameData *game, const uint8_t *data, size_t length, void *cb_data);
 
+typedef enum GamePacketType {
+    GP_Invite = 0u,
+    GP_Data,
+} GamePacketType;
 
 typedef enum GameWindowShape {
     GW_ShapeSquare = 0u,
@@ -105,6 +126,7 @@ struct GameData {
     size_t     level;
     GameStatus status;
     GameType   type;
+    bool       is_multiplayer;
 
     bool       show_lives;
     bool       show_score;
@@ -116,11 +138,20 @@ struct GameData {
 
     int        game_max_x; // max dimensions of game window
     int        game_max_y;
+
+    int        parent_max_x; // max dimensions of parent window
+    int        parent_max_y;
+
     int        window_id;
     WINDOW     *window;
-    const ToxWindow   *parent;
+
+    Tox        *tox;  // must be locked with Winthread mutex
+
     GameWindowShape    window_shape;
 
+    uint32_t id;  // indentifies multiplayer instance
+    uint32_t friend_number; // friendnumber associated with parent window
+
     cb_game_update_state *cb_game_update_state;
     void *cb_game_update_state_data;
 
@@ -135,6 +166,9 @@ struct GameData {
 
     cb_game_key_press *cb_game_key_press;
     void *cb_game_key_press_data;
+
+    cb_game_on_packet *cb_game_on_packet;
+    void *cb_game_on_packet_data;
 };
 
 
@@ -163,14 +197,32 @@ void game_set_cb_on_pause(GameData *game, cb_game_pause *func, void *cb_data);
  */
 void game_set_cb_on_keypress(GameData *game, cb_game_key_press *func, void *cb_data);
 
+/*
+ * Sets the callback for the game packet event.
+ */
+void game_set_cb_on_packet(GameData *game, cb_game_on_packet *func, void *cb_data);
+
 /*
  * Initializes game instance.
  *
+ * `type` must be a valid GameType.
+ *
+ * `id` should be a unique integer to indentify the game instance. If we're being invited to a game
+ *   this identifier should be sent via the invite packet.
+ *
+ * `force_small_window` will make the game window small.
+ *
+ * if `multiplayer_data` is non-null this indicates that we accepted a game invite from a contact.
+ *   The data contains any information we need to initialize the game state.
+ *
  * Return 0 on success.
  * Return -1 if screen is too small.
- * Return -2 on other failure.
+ * Return -2 on network related error.
+ * Return -3 if multiplayer game is being initialized outside of a contact's window.
+ * Return -4 on other failure.
  */
-int game_initialize(const ToxWindow *self, Tox *m, GameType type, bool force_small_window);
+int game_initialize(const ToxWindow *self, Tox *m, GameType type, uint32_t id, const uint8_t *multiplayer_data,
+                    size_t length, bool force_small_window);
 
 /*
  * Sets game window to `shape` and attempts to adjust size for best fit.
@@ -188,11 +240,21 @@ int game_set_window_shape(GameData *game, GameWindowShape shape);
  */
 GameType game_get_type(const char *game_string);
 
+/*
+ * Returns the name represented as a string associated with `type`.
+ */
+const char *game_get_name_string(GameType type);
+
 /*
  * Prints all available games to window associated with `self`.
  */
 void game_list_print(ToxWindow *self);
 
+/*
+ * Return true if game `type` has a multiplayer mode.
+ */
+bool game_type_is_multiplayer(GameType type);
+
 /*
  * Returns true if coordinates designated by `x` and `y` are within the game window boundaries.
  */
@@ -308,4 +370,15 @@ TIME_MS get_time_millis(void);
  */
 void game_kill(ToxWindow *self);
 
+/*
+ * Sends a packet containing payload `data` of size `length` to the friendnumber associated with the game's
+ * parent window.
+ *
+ * `length` must not exceed GAME_MAX_DATA_SIZE bytes.
+ *
+ * `packet_type` should be GP_Invite for an invite packet or GP_Data for all other game data.
+ */
+int game_send_packet(const GameData *game, const uint8_t *data, size_t length, GamePacketType packet_type);
+
 #endif // GAME_BASE
+

src/game_chess.h

@@ -25,6 +25,20 @@
 
 #include "game_base.h"
 
-int chess_initialize(GameData *game);
+/*
+ * Initializes chess game state.
+ *
+ * If `init_data` is non-null, this indicates that we were invited to the game.
+ *
+ * If we're the inviter, we send an invite packet after initialization. If we're the
+ * invitee, we send a handshake response packet to the inviter.
+ *
+ * Return 0 on success.
+ * Return -1 if window is too small.
+ * Return -2 on network related error.
+ * Return -3 on other error.
+ */
+int chess_initialize(GameData *game, const uint8_t *init_data, size_t length);
 
 #endif // GAME_CHESS
+

src/game_util.c

@@ -22,6 +22,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <stdint.h>
 
 #include "game_util.h"
 #include "toxic.h"
@@ -156,3 +157,38 @@ int game_util_random_colour(void)
             return RED;
     }
 }
+
+static size_t net_pack_u16(uint8_t *bytes, uint16_t v)
+{
+    bytes[0] = (v >> 8) & 0xff;
+    bytes[1] = v & 0xff;
+    return sizeof(v);
+}
+
+static size_t net_unpack_u16(const uint8_t *bytes, uint16_t *v)
+{
+    uint8_t hi = bytes[0];
+    uint8_t lo = bytes[1];
+    *v = ((uint16_t)hi << 8) | lo;
+    return sizeof(*v);
+}
+
+size_t game_util_pack_u32(uint8_t *bytes, uint32_t v)
+{
+    uint8_t *p = bytes;
+    p += net_pack_u16(p, (v >> 16) & 0xffff);
+    p += net_pack_u16(p, v & 0xffff);
+    return p - bytes;
+}
+
+size_t game_util_unpack_u32(const uint8_t *bytes, uint32_t *v)
+{
+    const uint8_t *p = bytes;
+    uint16_t hi;
+    uint16_t lo;
+    p += net_unpack_u16(p, &hi);
+    p += net_unpack_u16(p, &lo);
+    *v = ((uint32_t)hi << 16) | lo;
+    return p - bytes;
+}
+

src/game_util.h

@@ -89,4 +89,15 @@ void game_util_move_coords(Direction direction, Coords *coords);
  */
 int game_util_random_colour(void);
 
+/*
+ * Packs an unsigned 32 bit integer `v` into `bytes`.
+ */
+size_t game_util_pack_u32(uint8_t *bytes, uint32_t v);
+
+/*
+ * Unpacks an unsigned 32 bit integer in `bytes` to `v`.
+ */
+size_t game_util_unpack_u32(const uint8_t *bytes, uint32_t *v);
+
 #endif  // GAME_UTIL
+

src/global_commands.c

@@ -373,7 +373,8 @@ void cmd_game(WINDOW *window, ToxWindow *self, Tox *m, int argc, char (*argv)[MA
         }
     }
 
-    int ret = game_initialize(self, m, type, force_small);
+    uint32_t id = rand();
+    int ret = game_initialize(self, m, type, id, NULL, 0, force_small);
 
     switch (ret) {
         case 0: {
@@ -386,6 +387,18 @@ void cmd_game(WINDOW *window, ToxWindow *self, Tox *m, int argc, char (*argv)[MA
             return;
         }
 
+        case -2: {
+            line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "Game failed to initialize: Network error.");
+            return;
+
+        }
+
+        case -3: {
+            line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0,
+                          "Game is multiplayer only. Try the command again in the chat window of the contact you wish to play with.");
+            return;
+        }
+
         default: {
             line_info_add(self, false, NULL, NULL, SYS_MSG, 0, 0, "Game failed to initialize (error %d)", ret);
             return;

src/toxic.c

@@ -806,6 +806,7 @@ static void init_tox_callbacks(Tox *m)
     tox_callback_file_chunk_request(m, on_file_chunk_request);
     tox_callback_file_recv_control(m, on_file_recv_control);
     tox_callback_file_recv_chunk(m, on_file_recv_chunk);
+    tox_callback_friend_lossless_packet(m, on_lossless_custom_packet);
 }
 
 static void init_tox_options(struct Tox_Options *tox_opts)

src/toxic.h

@@ -135,5 +135,7 @@ void on_file_recv(Tox *m, uint32_t friendnumber, uint32_t filenumber, uint32_t k
                   const uint8_t *filename, size_t filename_length, void *userdata);
 void on_friend_typing(Tox *m, uint32_t friendnumber, bool is_typing, void *userdata);
 void on_friend_read_receipt(Tox *m, uint32_t friendnumber, uint32_t receipt, void *userdata);
+void on_lossless_custom_packet(Tox *m, uint32_t friendnumber, const uint8_t *data, size_t length, void *userdata);
+
 
 #endif /* TOXIC_H */

src/windows.c

@@ -323,6 +323,49 @@ void on_friend_read_receipt(Tox *m, uint32_t friendnumber, uint32_t receipt, voi
         }
     }
 }
+
+void on_lossless_custom_packet(Tox *m, uint32_t friendnumber, const uint8_t *data, size_t length, void *userdata)
+{
+    UNUSED_VAR(userdata);
+
+    if (length == 0 || data == NULL) {
+        return;
+    }
+
+    uint8_t type = data[0];
+
+    switch (type) {
+        case CUSTOM_PACKET_GAME_INVITE: {
+            for (size_t i = 0; i < MAX_WINDOWS_NUM; ++i) {
+                ToxWindow *window = windows[i];
+
+                if (window != NULL && window->onGameInvite != NULL) {
+                    window->onGameInvite(window, m, friendnumber, data + 1, length - 1);
+                }
+            }
+
+            break;
+        }
+
+        case CUSTOM_PACKET_GAME_DATA: {
+            for (size_t i = 0; i < MAX_WINDOWS_NUM; ++i) {
+                ToxWindow *window = windows[i];
+
+                if (window != NULL && window->onGameData != NULL) {
+                    window->onGameData(window, m, friendnumber, data + 1, length - 1);
+                }
+            }
+
+            break;
+        }
+
+        default: {
+            fprintf(stderr, "Got unknown custom packet of type: %u\n", type);
+            return;
+        }
+    }
+}
+
 /* CALLBACKS END */
 
 int add_window(Tox *m, ToxWindow *w)

src/windows.h

@@ -43,6 +43,13 @@
 #define TOP_BAR_HEIGHT 1
 #define WINDOW_BAR_HEIGHT 1
 
+
+typedef enum CustomPacket {
+    CUSTOM_PACKET_GAME_INVITE = 160,
+    CUSTOM_PACKET_GAME_DATA   = 161,
+} CustomPacket;
+
+
 /* ncurses colour pairs as FOREGROUND_BACKGROUND. No background defaults to black. */
 typedef enum {
     WHITE,
@@ -160,6 +167,10 @@ struct ToxWindow {
     void(*onTypingChange)(ToxWindow *, Tox *, uint32_t, bool);
     void(*onReadReceipt)(ToxWindow *, Tox *, uint32_t, uint32_t);
 
+    /* custom packets/games */
+    void(*onGameInvite)(ToxWindow *, Tox *, uint32_t, const uint8_t *, size_t);
+    void(*onGameData)(ToxWindow *, Tox *, uint32_t, const uint8_t *, size_t);
+
 #ifdef AUDIO
 
     void(*onInvite)(ToxWindow *, ToxAV *, uint32_t, int);