Add whitelist and rework command system

include/commands.h

@@ -0,0 +1,17 @@
+#ifndef COMMANDS_H
+#define COMMANDS_H
+
+#include "globals.h"
+#include "packets.h"
+#include "procedures.h"
+
+char *getNextArgument ();
+char *getRemainingArguments ();
+void handleCommand (PlayerData *sender, int message_len);
+#if MAX_WHITELISTED_PLAYERS > 0
+  void handleWhitelistCommand (PlayerData *sender);
+#endif
+void handleMessageCommand (PlayerData *sender);
+void handleHelpCommand (PlayerData *sender);
+
+#endif

include/globals.h

@@ -148,6 +148,9 @@
 // If defined, players are able to receive damage from nearby cacti.
 #define ENABLE_CACTUS_DAMAGE
 
+// If set to a number greater than 0, enables whitelist commands and functionality to prevent automated server scraping.
+#define MAX_WHITELISTED_PLAYERS 0
+
 // If defined, logs unrecognized packet IDs
 // #define DEV_LOG_UNKNOWN_PACKETS
 
@@ -186,6 +189,11 @@ extern uint8_t motd_len;
   extern uint8_t brand_len;
 #endif
 
+#if MAX_WHITELISTED_PLAYERS > 0
+  extern uint8_t enforce_whitelist;
+  extern char whitelisted_players[MAX_WHITELISTED_PLAYERS][16];
+#endif
+
 extern uint16_t client_count;
 
 typedef struct {

include/procedures.h

@@ -12,9 +12,16 @@ int getClientState (int client_fd);
 int getClientIndex (int client_fd);
 
 void resetPlayerData (PlayerData *player);
+
+#if MAX_WHITELISTED_PLAYERS > 0
+  uint8_t isPlayerWhitelisted (char *name);
+  uint8_t addPlayerToWhitelist (char *name);
+  uint8_t removePlayerFromWhitelist (char *name);
+#endif
+
 int reservePlayerData (int client_fd, uint8_t *uuid, char* name);
 int getPlayerData (int client_fd, PlayerData **output);
-PlayerData *getPlayerByName (int start_offset, int end_offset, uint8_t *buffer);
+PlayerData *getPlayerByName (char *name, uint8_t *buffer);
 void handlePlayerDisconnect (int client_fd);
 void handlePlayerJoin (PlayerData* player);
 void disconnectClient (int *client_fd, int cause);

src/commands.c

@@ -0,0 +1,173 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "globals.h"
+#include "commands.h"
+
+void handleCommand (PlayerData *player, int message_len) {
+  char* command = strtok((char *)recv_buffer, " ");
+  if (!strcmp(command, "!help")) {
+    handleHelpCommand(player);
+  } else if (!strcmp(command, "!msg")) {
+    handleMessageCommand(player);
+  #if MAX_WHITELISTED_PLAYERS > 0
+  } else if (!strcmp(command, "!whitelist")) {
+    handleWhitelistCommand(player);
+  #endif
+  } else {
+    sc_systemChat(player->client_fd, "§7Unknown command. Type !help for help.", 40);
+  }
+}
+
+// Pulls a single space-delimited argument from the chat buffer
+char *getNextArgument () {
+  return strtok(NULL, " ");
+}
+
+// Pulls the remaining text from the chat buffer
+char *getRemainingArguments () {
+  return strtok(NULL, "");
+}
+
+#if MAX_WHITELISTED_PLAYERS > 0
+void handleWhitelistCommand (PlayerData *player) {
+  char *first_arg = getNextArgument();
+
+  if (first_arg == NULL) {
+    goto usage;
+  }
+
+  if (!strcmp(first_arg, "on")) {
+    sc_systemChat(player->client_fd, "§aWhitelist has been enabled", 29);
+    enforce_whitelist = 1;
+    return;
+  } else if (!strcmp(first_arg, "off")) {
+    sc_systemChat(player->client_fd, "§cWhitelist has been disabled", 30);
+    enforce_whitelist = 0;
+    return;
+  } else if (!strcmp(first_arg, "add")) {
+    char* player_arg = getNextArgument();
+    if (player_arg == NULL) {
+      goto usage;
+    }
+    int player_len = strlen(player_arg);
+    if (player_len < 3 || player_len > 16) {
+        sc_systemChat(player->client_fd, "§cError: input username is invalid", 35);
+        return;
+    }
+    int result = addPlayerToWhitelist(player_arg);
+    if (result == 0) {
+      sc_systemChat(player->client_fd, "§7Successfully added player to the whitelist", 45);
+    } else if (result == 1) {
+      sc_systemChat(player->client_fd, "§cError: Player is already on the whitelist", 44);
+    } else {
+      sc_systemChat(player->client_fd, "§cError: The whitelist is full, remove other players first then try again", 74);
+    }
+    return;
+  } else if (!strcmp(first_arg, "remove")) {
+    char* player_arg = getNextArgument();
+    if (player_arg == NULL) {
+      goto usage;
+    }
+    int player_len = strlen(player_arg);
+    if (player_len < 3 || player_len > 16) {
+        sc_systemChat(player->client_fd, "§cError: input username is invalid", 35);
+        return;
+    }
+    if (removePlayerFromWhitelist(player_arg) == 0) {
+      sc_systemChat(player->client_fd, "§7Successfully removed player from the whitelist", 49);
+    } else {
+      sc_systemChat(player->client_fd, "§cError: Player is not on the whitelist", 40);
+    }
+    return;
+  } else if (!strcmp(first_arg, "list")) {
+    snprintf((char *)recv_buffer, sizeof(recv_buffer), "§7The currently whitelisted players are:");
+    recv_buffer[41] = ' ';
+    int length = 42;
+    int totalPlayers = 0;
+    for (int i = 0; i < MAX_WHITELISTED_PLAYERS; i ++) {
+      if (whitelisted_players[i][0] == '\0') continue;
+
+      totalPlayers++;
+
+      // If we run out of buffer space, then send what we have and loop back to the beginning of the buffer
+      if (length >= MAX_RECV_BUF_LEN - 18) {
+        printf("flushing buffer: len=%d, '%s'\n", length, recv_buffer);
+        sc_systemChat(player->client_fd, (char *)recv_buffer, length);
+        // Set beginning of buffer to '§7' to add chat color to next chunk
+        recv_buffer[0] = 0xC2;
+        recv_buffer[1] = 0xA7;
+        recv_buffer[2] = '7';
+        length = 3;
+      }
+
+      snprintf((char *)recv_buffer + length, sizeof(recv_buffer) - length, "%s, ", whitelisted_players[i]);
+      length += strlen(whitelisted_players[i]) + 2;
+    }
+    if (totalPlayers == 0) {
+        sc_systemChat(player->client_fd, "§7There are currently no whitelisted players", 45);
+        return;
+    }
+    // Subtract 2 from the length to remove the trailing comma and space
+    sc_systemChat(player->client_fd, (char *)recv_buffer, length - 2);
+    return;
+  }
+usage:
+  sc_systemChat(player->client_fd, "§7Usage: !whitelist <on|off|add|remove> [username]", 51);
+}
+#endif
+
+void handleMessageCommand (PlayerData* player) {
+  char* target_name = getNextArgument();
+
+  // Send usage guide if arguments are missing
+  if (target_name == NULL) goto usage;
+
+  // Query the target player
+  PlayerData *target = getPlayerByName(target_name, recv_buffer);
+  if (target == NULL) {
+    sc_systemChat(player->client_fd, "Player not found", 16);
+    return;
+  }
+
+  char *message = getRemainingArguments();
+
+  // Don't send empty messages
+  if (message == NULL) goto usage;
+
+  // Format output as a vanilla whisper
+  int name_len = strlen(player->name);
+  int text_len = strlen(message);
+  memmove(recv_buffer + name_len + 24, message, text_len);
+  snprintf((char *)recv_buffer, sizeof(recv_buffer), "§7§o%s whispers to you:", player->name);
+
+  // snprintf always null terminates strings, so we get rid of that here
+  recv_buffer[name_len + 23] = ' ';
+
+  // Send message to target player
+  sc_systemChat(target->client_fd, (char *)recv_buffer, (uint16_t)(name_len + 24 + text_len));
+
+  // Format output for sending player
+  int target_name_len = strlen(target->name);
+  memmove(recv_buffer + target_name_len + 23, recv_buffer + name_len + 24, text_len);
+  snprintf((char *)recv_buffer, sizeof(recv_buffer), "§7§oYou whisper to %s:", target->name);
+  recv_buffer[target_name_len + 22] = ' ';
+
+  // Report back to sending player
+  sc_systemChat(player->client_fd, (char *)recv_buffer, (uint16_t)(target_name_len + 23 + text_len));
+  return;
+
+usage:
+  sc_systemChat(player->client_fd, "§7Usage: !msg <player> <message>", 33);
+}
+
+void handleHelpCommand (PlayerData *player) {
+  // Send command guide
+  const char help_msg[] = "§7Commands:\n"
+  "  !msg <player> <message> - Send a private message\n"
+  #if MAX_WHITELISTED_PLAYERS > 0
+  "  !whitelist <on|off|add|remove> [username]\n"
+  #endif
+  "  !help - Show this help message";
+  sc_systemChat(player->client_fd, (char *)help_msg, (uint16_t)sizeof(help_msg) - 1);
+}

src/globals.c

@@ -45,6 +45,11 @@ uint8_t motd_len = sizeof(motd) - 1;
   uint8_t brand_len = sizeof(brand) - 1;
 #endif
 
+#if MAX_WHITELISTED_PLAYERS > 0
+  uint8_t enforce_whitelist = 0;
+  char whitelisted_players[MAX_WHITELISTED_PLAYERS][16];
+#endif
+
 uint16_t client_count;
 
 BlockChange block_changes[MAX_BLOCK_CHANGES];

src/main.c

@@ -81,6 +81,13 @@ void handlePacket (int client_fd, int length, int packet_id, int state) {
         uint8_t uuid[16];
         char name[16];
         if (cs_loginStart(client_fd, uuid, name)) break;
+        #if MAX_WHITELISTED_PLAYERS > 0
+        if (enforce_whitelist && !isPlayerWhitelisted(name)) {
+          printf("Disconnecting client %d because they are not on the whitelist\n", client_fd);
+          recv_count = 0;
+          return;
+        }
+        #endif
         if (reservePlayerData(client_fd, uuid, name)) {
           recv_count = 0;
           return;

src/packets.c

@@ -23,6 +23,7 @@
 #include "crafting.h"
 #include "procedures.h"
 #include "packets.h"
+#include "commands.h"
 
 // S->C Status Response (server list ping)
 int sc_statusResponse (int client_fd) {
@@ -1143,67 +1144,7 @@ int cs_chat (int client_fd) {
     goto cleanup;
   }
 
-  // Handle chat commands
-
-  if (!strncmp((char *)recv_buffer, "!msg", 4)) {
-
-    int target_offset = 5;
-    int target_end_offset = 0;
-    int text_offset = 0;
-
-    // Skip spaces after "!msg"
-    while (recv_buffer[target_offset] == ' ') target_offset++;
-    target_end_offset = target_offset;
-    // Extract target name
-    while (recv_buffer[target_end_offset] != ' ' && recv_buffer[target_end_offset] != '\0' && target_end_offset < 21) target_end_offset++;
-    text_offset = target_end_offset;
-    // Skip spaces before message
-    while (recv_buffer[text_offset] == ' ') text_offset++;
-
-    // Send usage guide if arguments are missing
-    if (target_offset == target_end_offset || target_end_offset == text_offset) {
-      sc_systemChat(client_fd, "§7Usage: !msg <player> <message>", 33);
-      goto cleanup;
-    }
-
-    // Query the target player
-    PlayerData *target = getPlayerByName(target_offset, target_end_offset, recv_buffer);
-    if (target == NULL) {
-      sc_systemChat(client_fd, "Player not found", 16);
-      goto cleanup;
-    }
-
-    // Format output as a vanilla whisper
-    int name_len = strlen(player->name);
-    int text_len = message_len - text_offset;
-    memmove(recv_buffer + name_len + 24, recv_buffer + text_offset, text_len);
-    snprintf((char *)recv_buffer, sizeof(recv_buffer), "§7§o%s whispers to you:", player->name);
-    recv_buffer[name_len + 23] = ' ';
-    // Send message to target player
-    sc_systemChat(target->client_fd, (char *)recv_buffer, (uint16_t)(name_len + 24 + text_len));
-
-    // Format output for sending player
-    int target_len = target_end_offset - target_offset;
-    memmove(recv_buffer + target_len + 23, recv_buffer + name_len + 24, text_len);
-    snprintf((char *)recv_buffer, sizeof(recv_buffer), "§7§oYou whisper to %s:", target->name);
-    recv_buffer[target_len + 22] = ' ';
-    // Report back to sending player
-    sc_systemChat(client_fd, (char *)recv_buffer, (uint16_t)(target_len + 23 + text_len));
-
-    goto cleanup;
-  }
-
-  if (!strncmp((char *)recv_buffer, "!help", 5)) {
-    // Send command guide
-    const char help_msg[] = "§7Commands:\n"
-    "  !msg <player> <message> - Send a private message\n"
-    "  !help - Show this help message";
-    sc_systemChat(client_fd, (char *)help_msg, (uint16_t)sizeof(help_msg) - 1);
-    goto cleanup;
-  }
-
-  // Handle fall-through case
-  sc_systemChat(client_fd, "§7Unknown command", 18);
+  handleCommand(player, message_len);
 
 cleanup:
   readUint64(client_fd); // Ignore timestamp