Discord Relay

An application for Linux, macOS, Windows (each GUI and console) and Android to forward Discord messages from one Discord server to another.

Setup

Discord Bot:

• Create a new application at https://discord.com/developers/applications.
• Add bot - don't make it public.
• Copy the bot token for configuring this app.
• Go to OAuth2 -> URL Generator, at "Scopes" check bot and then the following bot permissions: Read Messages/View Channels, Read Message History.
• Copy the URL and open it in the browser to add the bot to your server.
• Add bot to the channels that it should read.

Webhook:

• Create a webhook on the target server for a channel: Edit channel -> Integrations -> Create Webhook.
• Copy the webhook URL for the configuration of this application.

Notes

• If a message has been edited, it will currently not be relayed again.
• Messages in threads will currently not be relayed.
• The number of embeds that can be relayed is limited to 8.
• Only embeds of the "rich" type were tested, without video or provider fields.
• The channel and guild name in the footer of the relayed message does not contain commas or colons, they are replaced with a space if any are present.
• The channel ID fields in the UI can contain additional text at the end separated by a space.
• There's a limit of 1000 connections (excluding resumes) withing 24 hours. The bot token will be invalidated if this limit is exceeded. The app tries to keep track of this.
• Read this and this if you consider using a user token.
• Android: This app can significantly affect battery life as it has to constantly send data to Discord to maintain the WebSocket connection.
• The app icon is from https://www.appiconsios.com.

The configuration values for the desktop and Android apps are stored in different locations depending on the operating system:

• Linux: ~/.java/.userPrefs/tkhamez-discord-relay/prefs.xml
• Windows: Registry \HKEY_CURRENT_USER\SOFTWARE\JavaSoft\Prefs\tkhamez-discord-relay
• macOS: ~/Library/Preferences/com.apple.java.util.prefs.plist
• Android: In the Jetpack DataStore. They are deleted when the application is uninstalled.

The console app is configured with environment variables:

• DISCORD_RELAY_API_BASE_URL Optional, default: https://discord.com/api
• DISCORD_RELAY_TOKEN Required
• DISCORD_RELAY_IS_BOT_TOKEN 1 or 0, optional, default: 1
• DISCORD_RELAY_CHANNEL_IDS Comma separated list of channel IDs
• DISCORD_RELAY_ONLY_MENTION_EVERYONE Comma separated list of 1 or 0, position according to the channels in DISCORD_RELAY_CHANNEL_IDS, optional, default: 1
• DISCORD_RELAY_WEBHOOK

If the app crashes on macOS, try:

SKIKO_RENDER_API=SOFTWARE ./DiscordRelay.app/Contents/MacOS/DiscordRelay

Build

• Install OpenJDK 17.

Desktop

Run on each platform:

./gradlew createDistributable
# desktop/build/compose/binaries/main/app/

./gradlew packageUberJarForCurrentOS
# desktop/build/compose/jars/

Android

• Install Android SDK.
• Copy local.properties.dist to local.properties and adjust path or set ANDROID_HOME environment variable.

./gradlew android:build
# android/build/outputs/apk/

Create key store:

keytool -genkey -v -keystore misc/key-store.jks -keyalg RSA -keysize 2048 -validity 9131 -alias key0
(keytool -v -list -keystore misc/key-store.jks)

Sign:

zipalign -p -f -v 4 android/build/outputs/apk/release/android-release-unsigned.apk android/build/discord-relay.apk
apksigner sign --ks misc/key-store.jks android/build/discord-relay.apk
(apksigner verify -v android/build/discord-relay.apk)
(keytool -printcert -jarfile android/build/discord-relay.apk)

Console

./gradlew console:build
# console/build/distributions/

GitHub Workflow Configuration

• Base64 encode keystore: base64 -w 0 misc/key-store.jks > misc/key-store.jks.base64.txt.
• Create an action secret KEY_STORE with that value.
• Create an action secret KEY_STORE_PASS with the password for the key store.

Dev

Needs OpenJDK 17 and Android SDK.

Run server (uncomment "DebugButtons()" in App.kt to use it):

./gradlew server:run

Run Desktop app:

./gradlew desktop:run

Run console app:

./gradlew console:run

Use Android Studio to run the Android app.