Pumpkin-MC/Pumpkin · warning · PacketError

Unknown packet type

Error message

Unknown packet type: {0}

What it means

RconError::UnknownPacketType is thrown when an RCON packet's type field is an i32 that this implementation does not recognize. The Source RCON protocol defines only a few packet types (3=login, 2=command, 0=response/auth); any other value cannot be dispatched. This guards the server (or client) against protocol misuse and probing.

Solutions

1. Identify the client producing the packet and fix its packet-type value to a defined one (SERVERDATA_AUTH=3, SERVERDATA_EXECCOMMAND=2, SERVERDATA_RESPONSE_VALUE=0).
2. Log the offending i32 and close or ignore the connection; treat it as protocol abuse.
3. Update the library if a new official packet type must be supported.
4. Reject the packet early after reading the type field instead of decoding the body.

Example fix

// before: blindly sending a custom type
let packet = Packet { id, pkt_type: 99, body };

// after: use a defined type
use PacketType::Command;
let packet = Packet { id, pkt_type: Command, body };

// validate the type field before dispatch
const VALID: [i32; 3] = [0, 2, 3];
if !VALID.contains(&pkt_type) {
    drop_connection("unknown RCON packet type");
}

fn known_packet_type(t: i32) -> Option<PacketType> {
    match t { 0 => Some(PacketType::Response), 2 => Some(PacketType::Command), 3 => Some(PacketType::Auth), _ => None }
}

match decode_result {
    Err(RconError::UnknownPacketType(t)) => {
        warn!("rcon peer sent unknown type {t}; closing");
        connection.shutdown().await;
    }
    other => /* ... */,
}

When it happens

Trigger: Decoding an inbound RCON packet whose type field is outside the known set {0, 2, 3}; happens in Packet::decode when it calls the type-to-enum conversion with an unrecognized i32.

Common situations: A custom or buggy RCON client sending an invented packet type; a port scan or exploitation attempt sending random i32s; protocol version drift where a sender uses an extended type the receiver does not know.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• Invalid packet string body
• Failed to parse JSON into Game Profile
• Invalid URL
• Invalid slot
• Player ' ' tried to interact with a closed container

AI-assisted analysis of Pumpkin-MC/Pumpkin@8d4639e25a (2026-09-09). Data as JSON: /api/errors/3264cff2a7b01e88. Report an issue: GitHub.

Appendix: source

Thrown at crates/pumpkin-protocol/src/rcon.rs:60

        let bytes = body.as_bytes();
        buf.put_slice(bytes);
        buf.put_u8(0);
        buf.put_u8(0);
        buf
    }
}

#[derive(Error, Debug)]
pub enum PacketError {
    #[error("Invalid length")]
    InvalidLength,
    #[error("Failed to send packet: {0}")]
    FailedSend(std::io::Error),
    #[error("Missing packet null terminator")]
    MissingNullTerminator,
    #[error("Invalid packet string body: {0}")]
    InvalidBody(std::str::Utf8Error),
    #[error("Unknown packet type: {0}")]
    UnknownPacketType(i32),
}

#[derive(Debug, PartialEq, Eq)]
/// Serverbound packet
pub struct Packet {
    id: i32,
    ptype: ServerboundPacket,
    body: Box<str>,
}

impl Packet {
    pub fn deserialize(incoming: &mut Vec<u8>) -> Result<Option<Self>, PacketError> {
        // We need at least 4 bytes to read the packet length header
        if incoming.len() < 4 {
            return Ok(None);
        }

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