MinecraftConsoles/Minecraft.Server/docs/DEVELOPMENT.en.md

Minecraft.Server Developer Guide (English)

This document is for contributors who are new to Minecraft.Server and need a practical map for adding or modifying features safely.

1. What This Server Does

Minecraft.Server is the dedicated-server executable entry for this codebase.

Core responsibilities:

• Switch the process working directory to the executable folder before relative file I/O
• Load, normalize, and repair server.properties
• Initialize dedicated runtime systems, connection logging, and access control
• Load or create the target world and keep level-id aligned with the actual save destination
• Run the dedicated main loop (network tick, XUI actions, autosave, CLI input)
• Maintain operator-facing access files such as banned-players.json and banned-ips.json
• Perform an initial save for newly created worlds and then shut down safely

2. Important Files

Startup and Runtime

• Windows64/ServerMain.cpp
  • PrintUsage() and ParseCommandLine()
  • SetExeWorkingDirectory()
  • Runtime setup and shutdown flow
  • Initial save path for newly created worlds
  • Main loop, autosave scheduler, and CLI polling

World Selection and Save Load

• WorldManager.h
• WorldManager.cpp
  • Finds matching save by level-id first, then world-name fallback
  • Applies storage title + save ID consistently
  • Wait helpers for async storage/server action completion

Server Properties

• ServerProperties.h
• ServerProperties.cpp
  • Default values and normalization ranges
  • Parse/repair/write server.properties
  • Exposes ServerPropertiesConfig
  • SaveServerPropertiesConfig() rewrites level-name, level-id, and white-list

Access Control, Ban, and Whitelist Storage

• Access/Access.h
• Access/Access.cpp
  • Process-wide access-control facade
  • Published snapshot model used by console commands and login checks
• Access/BanManager.h
• Access/BanManager.cpp
  • Reads/writes banned-players.json and banned-ips.json
  • Normalizes identifiers and filters expired entries from snapshots
• Access/WhitelistManager.h
• Access/WhitelistManager.cpp
  • Reads/writes whitelist.json
  • Normalizes XUID-based whitelist entries used by login validation and CLI commands

Logging and Connection Audit

• ServerLogger.h
• ServerLogger.cpp
  • Log level parsing
  • Colored/timestamped console logs
  • General categories such as startup, world-io, console, access, network, and shutdown
• ServerLogManager.h
• ServerLogManager.cpp
  • Accepted/rejected TCP connection logs
  • Login/disconnect audit logs
  • Remote-IP cache used by ban-ip <player>

Console Command System

• Console/ServerCli.cpp (facade)
• Console/ServerCliInput.cpp (linenoise input thread + completion bridge)
• Console/ServerCliParser.cpp (tokenization, quoted args, completion context)
• Console/ServerCliEngine.cpp (dispatch, completion, helpers)
• Console/ServerCliRegistry.cpp (command registration + lookup)
• Console/commands/* (individual commands)

3. End-to-End Startup Flow

Main flow in Windows64/ServerMain.cpp:

1. SetExeWorkingDirectory() switches the current directory to the executable folder.
2. Load and normalize server.properties via LoadServerPropertiesConfig().
3. Copy config into DedicatedServerConfig, then apply CLI overrides (-port, -ip/-bind, -name, -maxplayers, -seed, -loglevel, -help/--help/-h).
4. Initialize process state, ServerLogManager, and Access::Initialize(".").
5. Initialize window/device/profile/network/thread-local systems.
6. Set host/game options from ServerPropertiesConfig.
7. Bootstrap world with BootstrapWorldForServer(...).
8. If world bootstrap resolves a different normalized save ID, persist it with SaveServerPropertiesConfig().
9. Start hosted game thread (RunNetworkGameThreadProc).
10. If a brand-new world was created, explicitly request one initial save.
11. Enter the main loop:

• TickCoreSystems()
• HandleXuiActions()
• serverCli.Poll()
• autosave scheduling

12. On shutdown:

• stop CLI input
• request save-on-exit / halt server
• wait for network shutdown completion
• terminate log, access, network, and device systems

4. Current Operator Surface

4.1 Launch Arguments

• -port <1-65535>
• -ip <addr> or -bind <addr>
• -name <name> (runtime max 16 chars)
• -maxplayers <1-8>
• -seed <int64>
• -loglevel <debug|info|warn|error>
• -help, --help, -h

Notes:

• CLI overrides affect only the current process.
• The only values currently written back by the server are level-name and level-id, and that happens when world bootstrap resolves identity changes.

4.2 Built-in Console Commands

• help / ?
• stop
• list
• ban <player> [reason ...]
  • currently requires the target player to be online
• ban-ip <address|player> [reason ...]
  • accepts a literal IPv4/IPv6 address or an online player's current remote IP
• pardon <player>
• pardon-ip <address>
  • only accepts a literal address
• banlist
• tp <player> <target> / teleport
• gamemode <survival|creative|0|1> [player] / gm

CLI behavior notes:

• Command parsing accepts both cmd and /cmd.
• Quoted arguments are supported by ServerCliParser.
• Completion is implemented per command via Complete(...).

4.3 Files Written Next to the Executable

• server.properties
• banned-players.json
• banned-ips.json

This follows from SetExeWorkingDirectory(), so these files are resolved relative to Minecraft.Server.exe, not the shell directory you launched from.

5. Common Development Tasks

5.1 Add a New CLI Command

Use this pattern when adding commands like /kick, /time, etc.

1. Add files under Console/commands/
   • CliCommandYourCommand.h
   • CliCommandYourCommand.cpp
2. Implement IServerCliCommand
   • Name(), Usage(), Description(), Execute(...)
   • optional: Aliases() and Complete(...)
3. Register the command in ServerCliEngine::RegisterDefaultCommands().
4. Add source/header to build definitions:
   • CMakeLists.txt (MINECRAFT_SERVER_SOURCES)
   • Minecraft.Server/Minecraft.Server.vcxproj (<ClCompile> / <ClInclude>)
5. Manual verify:
   • command appears in help
   • command executes correctly
   • completion works for both cmd and /cmd
   • quoted arguments behave as expected

Implementation references:

• CliCommandHelp.cpp for a simple no-arg command
• CliCommandTp.cpp for multi-arg + completion + runtime checks
• CliCommandGamemode.cpp for argument parsing and aliases
• CliCommandBanIp.cpp for access-backed behavior with connection metadata

5.2 Add or Change a server.properties Key

1. Add/update the field in ServerPropertiesConfig (ServerProperties.h).
2. Add a default entry to kServerPropertyDefaults (ServerProperties.cpp).
3. Load and normalize the value in LoadServerPropertiesConfig().
   • Use existing helpers for bool/int/string/int64/log level/level type.
4. If this value should be written back, update SaveServerPropertiesConfig().
   • Note: today that function intentionally only persists world identity.
5. Apply it to runtime where needed:
   • ApplyServerPropertiesToDedicatedConfig(...)
   • host options in ServerMain.cpp (app.SetGameHostOption(...))
   • PrintUsage() / ParseCommandLine() if the key also gets a CLI override
6. Manual verify:
   • missing key regeneration
   • invalid value normalization
   • clamped ranges still make sense
   • runtime behavior reflects the new value

Normalization details worth remembering:

• level-id is normalized to a safe save ID and length-limited.
• server-name is capped to 16 runtime chars.
• max-players is clamped to 1..8.
• autosave-interval is clamped to 5..3600.
• level-type normalizes to default or flat.

5.3 Change Ban / Access Behavior

Primary code lives in Access/Access.cpp, Access/BanManager.cpp, and ServerLogManager.cpp.

When changing this area:

• Keep BanManager responsible for storage/caching, not live-network policy.
• Keep the clone-and-publish snapshot pattern in Access.cpp so readers never block on disk I/O.
• Remember that ban-ip <player> depends on ServerLogManager::TryGetConnectionRemoteIp(...).
• Keep expired entries out of SnapshotBannedPlayers() / SnapshotBannedIps() output.
• Verify:
  • clean boot creates empty ban files when missing
  • ban, ban-ip, pardon, pardon-ip, and banlist still work
  • online bans disconnect live targets immediately
  • manual edits still reload safely if you later add or extend reload paths

5.4 Change World Load/Create Behavior

Primary code is in WorldManager.cpp.

Current matching policy:

1. Match by level-id (UTF8SaveFilename) first.
2. Fall back to world-name match on title/file name.

When changing this logic:

• Keep ApplyWorldStorageTarget(...) usage consistent (title + save ID together).
• Preserve periodic ticking in wait loops (tickProc) to avoid async deadlocks.
• Keep timeout/error logs specific enough for diagnosis.
• Verify:
  • existing world is reused correctly
  • no accidental new save directory creation
  • shutdown save still succeeds
  • newly created worlds still get the explicit initial save from ServerMain.cpp

5.5 Add Logging for New Feature Work

Use ServerLogger helpers:

• LogDebug, LogInfo, LogWarn, LogError
• formatted variants LogDebugf, LogInfof, etc.

Use ServerLogManager when the event is specifically part of the transport/login/disconnect lifecycle.

Recommended categories:

• startup for init/shutdown lifecycle
• world-io for save/world operations
• console for CLI command handling
• access for ban/access control state
• network for connection/login audit

6. Build and Run

From repository root:

cmake -S . -B build -G "Visual Studio 17 2022" -A x64
cmake --build build --config Debug --target MinecraftServer
cd .\build\Debug
.\Minecraft.Server.exe -port 25565 -bind 0.0.0.0 -maxplayers 8 -name DedicatedServer

Notes:

• The process switches its working directory to the executable directory at startup.
• server.properties, banned-players.json, and banned-ips.json are therefore read/written next to the executable.
• For Visual Studio workflow, see root COMPILE.md.

7. Safety Checklist Before Commit

• the server starts without crash when server.properties is missing or sparse
• missing access files are recreated on a clean boot
• existing world loads by expected level-id
• new world creation still performs the explicit initial save
• CLI input and completion remain responsive
• banlist output stays sane after adding/removing bans
• no busy-wait path removed from async wait loops
• both CMake and .vcxproj include newly added source files

8. Quick Troubleshooting

• Unknown command:
  • check RegisterDefaultCommands() and build-file entries
• server.properties or ban files seem to load from the wrong folder:
  • remember SetExeWorkingDirectory() moves the working directory to the executable folder
• Autosave or shutdown save timing out:
  • confirm wait loops still call TickCoreSystems() and HandleXuiActions() where required
• World not reused on restart:
  • inspect level-id normalization and matching logic in WorldManager.cpp
• ban-ip <player> cannot resolve an address:
  • confirm the player is currently online and ServerLogManager has a cached remote IP for that connection
• Settings not applied:
  • confirm the value is loaded into ServerPropertiesConfig, optionally copied into DedicatedServerConfig, and then applied in ServerMain.cpp