Bedrock Edition Networking Overview

Pumpkin features native support for Minecraft: Bedrock Edition clients (iOS, Android, Windows, Xbox, PlayStation, Switch).

Bedrock protocol structures and wire codecs reside in pumpkin-protocol::bedrock, while connection management and gameplay handlers reside in pumpkin::net::bedrock.

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Transport Layers: RakNet & NetherNet

Unlike Java Edition, which communicates exclusively over TCP streams, Bedrock Edition operates over UDP using two primary transport layers:

1. RakNet (Port 19132):
   • A reliable, sequenced UDP networking library originally developed by Jenkins Software.
   • Provides connection handshakes, packet acknowledgment (ACK/NACK), MTU negotiation, and packet splitting for payloads larger than the network MTU.
2. NetherNet:
   • Modern peer-to-peer and relayed transport protocol used by modern Bedrock versions.
   • Integrated in Pumpkin via crates/pumpkin/src/net/bedrock/nethernet.rs.

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Packet Framing & Batching (0xfe)

Bedrock does not send individual game packets over the network directly. Instead, multiple game packets are bundled into a single batch packet:

1. Header Byte: Every Bedrock game packet batch starts with 0xfe.
2. Compression: The payload following 0xfe is compressed using Deflate (or ZLib) above a negotiated threshold.
3. Sub-packet Framing: When decompressed, the batch contains one or more sequential game packets, each prefixed by its length encoded as a VarUInt.

In Pumpkin, batch decoding and assembly are managed by BedrockBatchDecoder and BedrockBatchEncoder in crates/pumpkin-protocol/src/bedrock/.

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Connection Lifecycle & State Progression

Bedrock does not have explicit protocol states like Java Edition. Instead, it follows a strict sequence of packets:

Step	Packet Exchanged	Purpose
1. Network Settings	SRequestNetworkSettings -> CNetworkSettings	Negotiates compression algorithm (Deflate/Snappy) and payload threshold
2. Authentication	SLogin -> CPlayStatus	Transmits JWT identity chain and client hardware data; verifies Xbox Live tokens
3. Resource Negotiation	CResourcePacksInfo -> SResourcePackClientResponse	Negotiates server resource packs and download behavior
4. World Initialization	CStartGame + CItemRegistry + CCreativeContent	Streams world spawn position, dimension settings, runtime player entity ID, and item palettes
5. Ready to Spawn	SSetLocalPlayerAsInitialized -> CPlayStatus	Signals client loading completion and transitions to active in-game play

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Packet Dispatching in pumpkin

Inside crates/pumpkin/src/net/bedrock/mod.rs, decompressed sub-packets are dispatched based on their numeric packet ID:

match packet.id {
    SPlayerAuthInput::PACKET_ID => {
        let packet = SPlayerAuthInput::read(reader)?;
        self.handle_player_auth_input(player, packet, server);
    }
    SRequestChunkRadius::PACKET_ID => {
        let packet = SRequestChunkRadius::read(reader)?;
        self.handle_request_chunk_radius(player, &packet);
    }
    SInventoryTransaction::PACKET_ID => {
        let packet = SInventoryTransaction::read(reader)?;
        self.handle_inventory_action(player, packet);
    }
    _ => {
        trace!("Unhandled Bedrock packet ID: {}", packet.id);
    }
}

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Authentication & NetherNet

• JWT Authentication: Bedrock verifies player identities via certificate chains signed by Microsoft / Xbox Live root authorities.
• NetherNet WebRTC: High-performance peer-to-peer transport using WebRTC DataChannels, ICE NAT traversal, and P-384 ECDSA keys.

For complete implementation details, see Bedrock Authentication & NetherNet.