Charset Handling

Purpose

Understanding how Rcon handles character encoding for commands and responses, especially for Minecraft color codes.

Overview

RCON is fundamentally a binary protocol, but text payloads are encoded as byte arrays. The choice of character encoding affects how color codes and special characters are preserved.

Default Encoding: UTF-8

UTF-8 is the default encoding for all text:

RconClient client = RconClient.builder()
    .host("localhost")
    .port(25575)
    .password("password")
    // UTF-8 is default
    .build();

UTF-8 works correctly for: * Standard ASCII text * Unicode characters (emoji, international characters) * Most command output

Color Code Encoding: ISO-8859-1

Minecraft uses section signs (§) for color codes. These color codes are not standard ASCII and require special handling.

The Problem

In UTF-8, the section sign (§) is encoded as two bytes: * § = 0xC2 0xA7 (UTF-8)

However, Minecraft’s internal encoding treats it as: * § = 0xA7 (single byte, ISO-8859-1)

This mismatch can corrupt color codes in responses.

The Solution

Use ISO-8859-1 (also called Latin-1) charset to preserve color codes:

RconClient client = RconClient.builder()
    .host("localhost")
    .port(25575)
    .password("password")
    .charset(StandardCharsets.ISO_8859_1)
    .build();

Example: Color Code Preservation

// With UTF-8 (default)
RconClient utf8Client = RconClient.builder()
    .host("localhost")
    .port(25575)
    .password("password")
    .build();

RconResponse response = utf8Client.sendCommand("list");
System.out.println(response.getResponse());
// Output: ??c[Server] ??fOnline players: 3
// Color codes are corrupted!

// With ISO-8859-1
RconClient latin1Client = RconClient.builder()
    .host("localhost")
    .port(25575)
    .password("password")
    .charset(StandardCharsets.ISO_8859_1)
    .build();

RconResponse response = latin1Client.sendCommand("list");
System.out.println(response.getResponse());
// Output: §c[Server] §fOnline players: 3
// Color codes are preserved!

Minecraft Color Codes

Standard Minecraft color codes:

Code	Color	Name
§0	Black	BLACK
§1	Dark Blue	DARK_BLUE
§2	Dark Green	DARK_GREEN
§3	Dark Aqua	DARK_AQUA
§4	Dark Red	DARK_RED
§5	Dark Purple	DARK_PURPLE
§6	Gold	GOLD
§7	Gray	GRAY
§8	Dark Gray	DARK_GRAY
§9	Blue	BLUE
§a	Green	GREEN
§b	Aqua	AQUA
§c	Red	RED
§d	Light Purple	LIGHT_PURPLE
§e	Yellow	YELLOW
§f	White	WHITE

Formatting codes:

Code	Effect	Name
§k	Obfuscated	MAGIC
§l	Bold	BOLD
§m	Strikethrough	STRIKETHROUGH
§n	Underline	UNDERLINE
§o	Italic	ITALIC
§r	Reset	RESET

When to Use Each Encoding

Use UTF-8 (Default) When:

• You don’t need color codes

• Working with international characters

• Processing log files

• Using modern Minecraft versions without color codes

RconClient client = RconClient.builder()
    .host("localhost")
    .port(25575)
    .password("password")
    // UTF-8 is default, no need to specify
    .build();

Use ISO-8859-1 When:

• You need to preserve Minecraft color codes

• Processing chat messages with formatting

• Parsing server responses with § codes

• Working with legacy Minecraft versions

RconClient client = RconClient.builder()
    .host("localhost")
    .port(25575)
    .password("password")
    .charset(StandardCharsets.ISO_8859_1)
    .build();

Encoding Comparison

String text = "§c[Server] §fWelcome!";

// UTF-8 encoding
byte[] utf8 = text.getBytes(StandardCharsets.UTF_8);
// Result: C2 A7 63 5B 53 65 72 76 65 72 5D 20 C2 A7 66 57 65 6C 63 6F 6D 65 21

// ISO-8859-1 encoding
byte[] latin1 = text.getBytes(StandardCharsets.ISO_8859_1);
// Result: A7 63 5B 53 65 72 76 65 72 5D 20 A7 66 57 65 6C 63 6F 6D 65 21

// UTF-8 uses 2 bytes for § (C2 A7)
// ISO-8859-1 uses 1 byte for § (A7)

Strip Color Codes

If you don’t need color codes, strip them for cleaner output:

public static String stripColorCodes(String input) {
    return input.replaceAll("§[0-9a-fk-or]", "");
}

String response = client.sendCommand("list").getResponse();
String cleanResponse = stripColorCodes(response);
System.out.println(cleanResponse);
// Output: [Server] Online players: 3

Performance Notes

• ISO-8859-1 is slightly faster than UTF-8 (single-byte encoding)

• Both are hardware-accelerated on modern JVMs

• Performance difference is negligible for typical RCON usage

See Also

• Packet Protocol - Binary packet structure

• Common Configurations - Client setup examples

• Protocol Specification - Complete protocol docs