iggy_binary_protocol 0.11.1-edge.2

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

use bytemuck::{CheckedBitPattern, NoUninit};
use enumset::EnumSetType;

/// VSR message type discriminant.
#[derive(Default, Debug, EnumSetType)]
#[repr(u8)]
pub enum Command {
    #[default]
    Reserved = 0,

    Ping = 1,
    Pong = 2,
    PingClient = 3,
    PongClient = 4,

    Request = 5,
    Prepare = 6,
    PrepareOk = 7,
    Reply = 8,
    Commit = 9,

    StartViewChange = 10,
    DoViewChange = 11,
    StartView = 12,
    Eviction = 13,

    // Replica-to-replica auth handshake (the server consensus plane).
    ReplicaHello = 14,
    ReplicaChallenge = 15,
    ReplicaFinish = 16,

    // Replica recovery: a restarted replica asks for the current view's
    // `StartView` instead of trusting stale local state; only that view's
    // primary answers (with a targeted `StartView`).
    RequestStartView = 17,

    // Journal repair: fetch committed prepares a replica is missing (rejoin
    // window or interior hole). `RepairPrepare` carries a journaled prepare
    // verbatim; `RangeEvicted` is the honest answer when the serving peer no
    // longer retains the front of the range.
    RequestPrepares = 18,
    RepairPrepare = 19,
    RepairDone = 20,
    RangeEvicted = 21,

    // State transfer (metadata plane): a restarted replica replaces its
    // snapshot-shaped state (metadata snapshot + client table) from the
    // current primary, then journal repair covers the tail. Pull-based:
    // the requester asks for the target descriptor, then fetches each
    // artifact in bounded chunks (per-peer bus queues drop overruns
    // silently, so push cannot work).
    RequestStateTransfer = 22,
    StateTransferTarget = 23,
    RequestStateChunk = 24,
    StateChunk = 25,

    // Register forwarding: a client that dialed a backup authenticates
    // there, and only the consensus proposal travels to the primary. The
    // backup forwards the verified identity and parks the login on the
    // matching `ForwardRegisterResult`.
    ForwardRegister = 26,
    ForwardRegisterResult = 27,

    // Logout forwarding: a session bound on a backup asks the primary to
    // commit its replicated teardown, then the backup answers the client on
    // the connection it owns.
    ForwardLogout = 28,
    ForwardLogoutResult = 29,

    // Backups report transport-bound sessions to the metadata primary. No reply.
    ConsumerSessionHeartbeat = 30,
    SessionRetirementProgress = 31,

    // A backup relays a partition completion to the metadata primary, which
    // may hold no replica of that partition. No reply: the commit replicates
    // back.
    ForwardCompletion = 32,

    // Fresh metadata and partition readiness for primary rebalancing.
    PrimaryRebalance = 33,
    SegmentDelete = 34,
}

// SAFETY: Command is #[repr(u8)] with no padding bytes.
unsafe impl NoUninit for Command {}

// SAFETY: Command is #[repr(u8)]; is_valid_bit_pattern matches all defined discriminants.
unsafe impl CheckedBitPattern for Command {
    type Bits = u8;

    fn is_valid_bit_pattern(bits: &u8) -> bool {
        *bits <= Self::SegmentDelete as u8
    }
}

#[cfg(test)]
mod tests {
    use crate::consensus::GenericHeader;
    use aligned_vec::{AVec, ConstAlign};

    #[test]
    fn invalid_bit_pattern_rejected() {
        // 16-byte aligned (see `ConsensusHeader` doc); `BytesMut` fails Miri.
        let mut buf: AVec<u8, ConstAlign<16>> = AVec::new(16);
        buf.resize(256, 0);
        buf[60] = 99;
        let result = bytemuck::checked::try_from_bytes::<GenericHeader>(&buf);
        assert!(result.is_err());
    }

    #[test]
    fn replica_auth_commands_are_valid_bit_patterns() {
        for command in 14u8..=34 {
            let mut buf: AVec<u8, ConstAlign<16>> = AVec::new(16);
            buf.resize(256, 0);
            buf[60] = command;
            assert!(bytemuck::checked::try_from_bytes::<GenericHeader>(&buf).is_ok());
        }
        let mut buf: AVec<u8, ConstAlign<16>> = AVec::new(16);
        buf.resize(256, 0);
        buf[60] = 35;
        assert!(bytemuck::checked::try_from_bytes::<GenericHeader>(&buf).is_err());
    }
}