mls_rs/group/

proposal.rs

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// Copyright by contributors to this project.
// SPDX-License-Identifier: (Apache-2.0 OR MIT)

use alloc::{boxed::Box, vec::Vec};

#[cfg(feature = "by_ref_proposal")]
use crate::tree_kem::leaf_node::LeafNode;

use crate::{
    client::MlsError, tree_kem::node::LeafIndex, CipherSuite, KeyPackage, MlsMessage,
    ProtocolVersion,
};
use core::fmt::{self, Debug};
use mls_rs_codec::{MlsDecode, MlsEncode, MlsSize};
use mls_rs_core::{group::Capabilities, identity::SigningIdentity};

#[cfg(feature = "by_ref_proposal")]
use crate::group::proposal_ref::ProposalRef;

pub use mls_rs_core::extension::ExtensionList;
pub use mls_rs_core::group::ProposalType;

#[cfg(feature = "psk")]
use crate::psk::{ExternalPskId, JustPreSharedKeyID, PreSharedKeyID};

#[derive(Clone, Debug, PartialEq, MlsSize, MlsEncode, MlsDecode)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
/// A proposal that adds a member to a [`Group`](crate::group::Group).
pub struct AddProposal {
    pub(crate) key_package: KeyPackage,
}

impl AddProposal {
    /// The [`KeyPackage`] used by this proposal to add
    /// a [`Member`](mls_rs_core::group::Member) to the group.
    pub fn key_package(&self) -> &KeyPackage {
        &self.key_package
    }

    /// The [`SigningIdentity`] of the [`Member`](mls_rs_core::group::Member)
    /// that will be added by this proposal.
    pub fn signing_identity(&self) -> &SigningIdentity {
        self.key_package.signing_identity()
    }

    /// Client [`Capabilities`] of the [`Member`](mls_rs_core::group::Member)
    /// that will be added by this proposal.
    pub fn capabilities(&self) -> Capabilities {
        self.key_package.leaf_node.ungreased_capabilities()
    }

    /// Key package extensions that are assoiciated with the
    /// [`Member`](mls_rs_core::group::Member) that will be added by this proposal.
    pub fn key_package_extensions(&self) -> ExtensionList {
        self.key_package.ungreased_extensions()
    }

    /// Leaf node extensions that will be entered into the group state for the
    /// [`Member`](mls_rs_core::group::Member) that will be added.
    pub fn leaf_node_extensions(&self) -> ExtensionList {
        self.key_package.leaf_node.ungreased_extensions()
    }
}

impl From<KeyPackage> for AddProposal {
    fn from(key_package: KeyPackage) -> Self {
        Self { key_package }
    }
}

impl TryFrom<MlsMessage> for AddProposal {
    type Error = MlsError;

    fn try_from(value: MlsMessage) -> Result<Self, Self::Error> {
        value
            .into_key_package()
            .ok_or(MlsError::UnexpectedMessageType)
            .map(Into::into)
    }
}

#[cfg(feature = "by_ref_proposal")]
#[derive(Clone, Debug, PartialEq, MlsSize, MlsEncode, MlsDecode)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
/// A proposal that will update an existing [`Member`](mls_rs_core::group::Member) of a
/// [`Group`](crate::group::Group).
pub struct UpdateProposal {
    pub(crate) leaf_node: LeafNode,
}

#[cfg(feature = "by_ref_proposal")]
impl UpdateProposal {
    /// The new [`SigningIdentity`] of the [`Member`](mls_rs_core::group::Member)
    /// that is being updated by this proposal.
    pub fn signing_identity(&self) -> &SigningIdentity {
        &self.leaf_node.signing_identity
    }

    /// New Client [`Capabilities`] of the [`Member`](mls_rs_core::group::Member)
    /// that will be updated by this proposal.
    pub fn capabilities(&self) -> Capabilities {
        self.leaf_node.ungreased_capabilities()
    }

    /// New Leaf node extensions that will be entered into the group state for the
    /// [`Member`](mls_rs_core::group::Member) that is being updated by this proposal.
    pub fn leaf_node_extensions(&self) -> ExtensionList {
        self.leaf_node.ungreased_extensions()
    }
}

#[derive(Clone, Debug, PartialEq, Eq, MlsSize, MlsEncode, MlsDecode)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
/// A proposal to remove an existing [`Member`](mls_rs_core::group::Member) of a
/// [`Group`](crate::group::Group).
pub struct RemoveProposal {
    pub(crate) to_remove: LeafIndex,
}

impl RemoveProposal {
    /// The index of the [`Member`](mls_rs_core::group::Member) that will be removed by
    /// this proposal.
    pub fn to_remove(&self) -> u32 {
        *self.to_remove
    }
}

impl RemoveProposal {
    pub fn removing(member_index: u32) -> Result<Self, MlsError> {
        Ok(Self {
            to_remove: LeafIndex::try_from(member_index)?,
        })
    }
}

impl TryFrom<u32> for RemoveProposal {
    type Error = MlsError;

    fn try_from(value: u32) -> Result<Self, Self::Error> {
        Self::removing(value)
    }
}

#[cfg(feature = "psk")]
#[derive(Clone, Debug, PartialEq, Eq, MlsSize, MlsEncode, MlsDecode)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
/// A proposal to add a pre-shared key to a group.
pub struct PreSharedKeyProposal {
    pub(crate) psk: PreSharedKeyID,
}

#[cfg(feature = "psk")]
impl PreSharedKeyProposal {
    /// The external pre-shared key id of this proposal.
    ///
    /// MLS requires the pre-shared key type for PreSharedKeyProposal to be of
    /// type `External`.
    ///
    /// Returns `None` in the condition that the underlying psk is not external.
    pub fn external_psk_id(&self) -> Option<&ExternalPskId> {
        match self.psk.key_id {
            JustPreSharedKeyID::External(ref ext) => Some(ext),
            JustPreSharedKeyID::Resumption(_) => None,
        }
    }
}

#[derive(Clone, PartialEq, MlsSize, MlsEncode, MlsDecode)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
/// A proposal to reinitialize a group using new parameters.
pub struct ReInitProposal {
    #[mls_codec(with = "mls_rs_codec::byte_vec")]
    #[cfg_attr(feature = "serde", serde(with = "mls_rs_core::vec_serde"))]
    pub(crate) group_id: Vec<u8>,
    pub(crate) version: ProtocolVersion,
    pub(crate) cipher_suite: CipherSuite,
    pub(crate) extensions: ExtensionList,
}

impl Debug for ReInitProposal {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("ReInitProposal")
            .field(
                "group_id",
                &mls_rs_core::debug::pretty_group_id(&self.group_id),
            )
            .field("version", &self.version)
            .field("cipher_suite", &self.cipher_suite)
            .field("extensions", &self.extensions)
            .finish()
    }
}

impl ReInitProposal {
    /// The unique id of the new group post reinitialization.
    pub fn group_id(&self) -> &[u8] {
        &self.group_id
    }

    /// The new protocol version to use post reinitialization.
    pub fn new_version(&self) -> ProtocolVersion {
        self.version
    }

    /// The new ciphersuite to use post reinitialization.
    pub fn new_cipher_suite(&self) -> CipherSuite {
        self.cipher_suite
    }

    /// Group context extensions to set in the new group post reinitialization.
    pub fn new_group_context_extensions(&self) -> &ExtensionList {
        &self.extensions
    }
}

#[derive(Clone, PartialEq, Eq, MlsSize, MlsEncode, MlsDecode)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
/// A proposal used for external commits.
pub struct ExternalInit {
    #[mls_codec(with = "mls_rs_codec::byte_vec")]
    #[cfg_attr(feature = "serde", serde(with = "mls_rs_core::vec_serde"))]
    pub(crate) kem_output: Vec<u8>,
}

impl Debug for ExternalInit {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("ExternalInit").finish()
    }
}

#[derive(Clone, PartialEq, Eq, MlsSize, MlsEncode, MlsDecode, Debug)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg(all(
    feature = "by_ref_proposal",
    feature = "custom_proposal",
    feature = "self_remove_proposal"
))]
/// A proposal to remove the current [`Member`](mls_rs_core::group::Member) of a
/// [`Group`](crate::group::Group).
pub struct SelfRemoveProposal {}

#[cfg(feature = "custom_proposal")]
#[derive(Clone, PartialEq, Eq)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(
    all(feature = "ffi", not(test)),
    safer_ffi_gen::ffi_type(clone, opaque)
)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
/// A user defined custom proposal.
///
/// User defined proposals are passed through the protocol as an opaque value.
pub struct CustomProposal {
    proposal_type: ProposalType,
    #[cfg_attr(feature = "serde", serde(with = "mls_rs_core::vec_serde"))]
    data: Vec<u8>,
}

#[cfg(feature = "custom_proposal")]
impl Debug for CustomProposal {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("CustomProposal")
            .field("proposal_type", &self.proposal_type)
            .field("data", &mls_rs_core::debug::pretty_bytes(&self.data))
            .finish()
    }
}

#[cfg(feature = "custom_proposal")]
#[cfg_attr(all(feature = "ffi", not(test)), safer_ffi_gen::safer_ffi_gen)]
impl CustomProposal {
    /// Create a custom proposal.
    ///
    /// # Warning
    ///
    /// Avoid using the [`ProposalType`] values that have constants already
    /// defined by this crate. Using existing constants in a custom proposal
    /// has unspecified behavior.
    pub fn new(proposal_type: ProposalType, data: Vec<u8>) -> Self {
        Self {
            proposal_type,
            data,
        }
    }

    /// The proposal type used for this custom proposal.
    pub fn proposal_type(&self) -> ProposalType {
        self.proposal_type
    }

    /// The opaque data communicated by this custom proposal.
    pub fn data(&self) -> &[u8] {
        &self.data
    }
}

#[cfg(feature = "custom_proposal")]
/// Encode/Decode for the `data` field of CustomProposal. This allows specialization over
/// the decoding based on the ProposalType, if users want to use an encoding other than the
/// default bytes vector (in particular, if users want the CustomProposal wrapper to be hidden
/// in the encoding, so the underlying custom proposal can be decoded directly).
pub trait CustomDecoder: Sized {
    fn encode_from_bytes(
        data: &Vec<u8>,
        writer: &mut Vec<u8>,
        _proposal_type: &ProposalType,
    ) -> Result<(), mls_rs_codec::Error> {
        mls_rs_codec::byte_vec::mls_encode(data, writer)
    }
    fn decode_from_bytes(
        reader: &mut &[u8],
        _proposal_type: &ProposalType,
    ) -> Result<Vec<u8>, mls_rs_codec::Error> {
        mls_rs_codec::byte_vec::mls_decode(reader)
    }
    fn encoded_byte_len(data: &Vec<u8>, _proposal_type: &ProposalType) -> usize {
        mls_rs_codec::byte_vec::mls_encoded_len(data)
    }
}

#[cfg(all(feature = "custom_proposal", not(feature = "gsma_rcs_e2ee_feature")))]
impl CustomDecoder for CustomProposal {}

#[cfg(all(feature = "custom_proposal", feature = "gsma_rcs_e2ee_feature"))]
impl CustomDecoder for CustomProposal {
    fn encode_from_bytes(
        data: &Vec<u8>,
        writer: &mut Vec<u8>,
        proposal_type: &ProposalType,
    ) -> Result<(), mls_rs_codec::Error> {
        match proposal_type {
            // directly extend with the serialized proposals; don't encode as a byte array
            // as the length should not be included in the encoding
            &ProposalType::RCS_SIGNATURE | &ProposalType::RCS_SERVER_REMOVE => {
                writer.extend(data);
                Ok(())
            }
            _ => mls_rs_codec::byte_vec::mls_encode(data, writer),
        }
    }
    fn decode_from_bytes(
        reader: &mut &[u8],
        proposal_type: &ProposalType,
    ) -> Result<Vec<u8>, mls_rs_codec::Error> {
        match *proposal_type {
            // empty struct
            ProposalType::RCS_SIGNATURE => Ok(Vec::new()),
            // remove proposal
            ProposalType::RCS_SERVER_REMOVE => {
                let decoded = RemoveProposal::mls_decode(reader)?;
                let mut writer = Vec::new();
                RemoveProposal::mls_encode(&decoded, &mut writer)?;
                // return, to be used in the data field of CustomProposal, the encoded proposal
                Ok(writer)
            }
            _ => mls_rs_codec::byte_vec::mls_decode(reader),
        }
    }
    fn encoded_byte_len(data: &Vec<u8>, proposal_type: &ProposalType) -> usize {
        match proposal_type {
            &ProposalType::RCS_SIGNATURE | &ProposalType::RCS_SERVER_REMOVE => data.len(),
            _ => mls_rs_codec::byte_vec::mls_encoded_len(data),
        }
    }
}

/// Trait to simplify creating custom proposals that are serialized with MLS
/// encoding.
#[cfg(feature = "custom_proposal")]
pub trait MlsCustomProposal: MlsSize + MlsEncode + MlsDecode + Sized {
    fn proposal_type() -> ProposalType;

    fn to_custom_proposal(&self) -> Result<CustomProposal, mls_rs_codec::Error> {
        Ok(CustomProposal::new(
            Self::proposal_type(),
            self.mls_encode_to_vec()?,
        ))
    }

    fn from_custom_proposal(proposal: &CustomProposal) -> Result<Self, mls_rs_codec::Error> {
        if proposal.proposal_type() != Self::proposal_type() {
            // #[cfg(feature = "std")]
            // return Err(mls_rs_codec::Error::Custom(
            //     "invalid proposal type".to_string(),
            // ));

            //#[cfg(not(feature = "std"))]
            return Err(mls_rs_codec::Error::Custom(4));
        }

        Self::mls_decode(&mut proposal.data())
    }
}

#[allow(clippy::large_enum_variant)]
#[derive(Clone, Debug, PartialEq)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[repr(u16)]
#[non_exhaustive]
/// An enum that represents all possible types of proposals.
pub enum Proposal {
    Add(alloc::boxed::Box<AddProposal>),
    #[cfg(feature = "by_ref_proposal")]
    Update(UpdateProposal),
    Remove(RemoveProposal),
    #[cfg(feature = "psk")]
    Psk(PreSharedKeyProposal),
    ReInit(ReInitProposal),
    ExternalInit(ExternalInit),
    GroupContextExtensions(ExtensionList),
    #[cfg(all(
        feature = "by_ref_proposal",
        feature = "custom_proposal",
        feature = "self_remove_proposal"
    ))]
    SelfRemove(SelfRemoveProposal),
    #[cfg(feature = "custom_proposal")]
    Custom(CustomProposal),
}

impl MlsSize for Proposal {
    fn mls_encoded_len(&self) -> usize {
        let inner_len = match self {
            Proposal::Add(p) => p.mls_encoded_len(),
            #[cfg(feature = "by_ref_proposal")]
            Proposal::Update(p) => p.mls_encoded_len(),
            Proposal::Remove(p) => p.mls_encoded_len(),
            #[cfg(feature = "psk")]
            Proposal::Psk(p) => p.mls_encoded_len(),
            Proposal::ReInit(p) => p.mls_encoded_len(),
            Proposal::ExternalInit(p) => p.mls_encoded_len(),
            Proposal::GroupContextExtensions(p) => p.mls_encoded_len(),
            #[cfg(all(
                feature = "by_ref_proposal",
                feature = "custom_proposal",
                feature = "self_remove_proposal"
            ))]
            Proposal::SelfRemove(p) => p.mls_encoded_len(),
            #[cfg(feature = "custom_proposal")]
            Proposal::Custom(p) => CustomProposal::encoded_byte_len(&p.data, &p.proposal_type),
        };

        self.proposal_type().mls_encoded_len() + inner_len
    }
}

impl MlsEncode for Proposal {
    fn mls_encode(&self, writer: &mut Vec<u8>) -> Result<(), mls_rs_codec::Error> {
        self.proposal_type().mls_encode(writer)?;

        match self {
            Proposal::Add(p) => p.mls_encode(writer),
            #[cfg(feature = "by_ref_proposal")]
            Proposal::Update(p) => p.mls_encode(writer),
            Proposal::Remove(p) => p.mls_encode(writer),
            #[cfg(feature = "psk")]
            Proposal::Psk(p) => p.mls_encode(writer),
            Proposal::ReInit(p) => p.mls_encode(writer),
            Proposal::ExternalInit(p) => p.mls_encode(writer),
            Proposal::GroupContextExtensions(p) => p.mls_encode(writer),
            #[cfg(all(
                feature = "by_ref_proposal",
                feature = "custom_proposal",
                feature = "self_remove_proposal"
            ))]
            Proposal::SelfRemove(p) => p.mls_encode(writer),
            #[cfg(feature = "custom_proposal")]
            Proposal::Custom(p) => {
                if p.proposal_type.raw_value() <= 7 {
                    // #[cfg(feature = "std")]
                    // return Err(mls_rs_codec::Error::Custom(
                    //     "custom proposal types can not be set to defined values of 0-7".to_string(),
                    // ));

                    // #[cfg(not(feature = "std"))]
                    return Err(mls_rs_codec::Error::Custom(2));
                }
                CustomProposal::encode_from_bytes(&p.data, writer, &p.proposal_type)
            }
        }
    }
}

impl MlsDecode for Proposal {
    fn mls_decode(reader: &mut &[u8]) -> Result<Self, mls_rs_codec::Error> {
        let proposal_type = ProposalType::mls_decode(reader)?;

        Ok(match proposal_type {
            ProposalType::ADD => {
                Proposal::Add(alloc::boxed::Box::new(AddProposal::mls_decode(reader)?))
            }
            #[cfg(feature = "by_ref_proposal")]
            ProposalType::UPDATE => Proposal::Update(UpdateProposal::mls_decode(reader)?),
            ProposalType::REMOVE => Proposal::Remove(RemoveProposal::mls_decode(reader)?),
            #[cfg(feature = "psk")]
            ProposalType::PSK => Proposal::Psk(PreSharedKeyProposal::mls_decode(reader)?),
            ProposalType::RE_INIT => Proposal::ReInit(ReInitProposal::mls_decode(reader)?),
            ProposalType::EXTERNAL_INIT => {
                Proposal::ExternalInit(ExternalInit::mls_decode(reader)?)
            }
            ProposalType::GROUP_CONTEXT_EXTENSIONS => {
                Proposal::GroupContextExtensions(ExtensionList::mls_decode(reader)?)
            }
            #[cfg(all(
                feature = "by_ref_proposal",
                feature = "custom_proposal",
                feature = "self_remove_proposal"
            ))]
            ProposalType::SELF_REMOVE => {
                Proposal::SelfRemove(SelfRemoveProposal::mls_decode(reader)?)
            }
            #[cfg(feature = "custom_proposal")]
            custom => Proposal::Custom(CustomProposal {
                proposal_type: custom,
                data: CustomProposal::decode_from_bytes(reader, &custom)?,
            }),
            // TODO fix test dependency on openssl loading codec with default features
            #[cfg(not(feature = "custom_proposal"))]
            _ => return Err(mls_rs_codec::Error::Custom(3)),
        })
    }
}

impl Proposal {
    pub fn proposal_type(&self) -> ProposalType {
        match self {
            Proposal::Add(_) => ProposalType::ADD,
            #[cfg(feature = "by_ref_proposal")]
            Proposal::Update(_) => ProposalType::UPDATE,
            Proposal::Remove(_) => ProposalType::REMOVE,
            #[cfg(feature = "psk")]
            Proposal::Psk(_) => ProposalType::PSK,
            Proposal::ReInit(_) => ProposalType::RE_INIT,
            Proposal::ExternalInit(_) => ProposalType::EXTERNAL_INIT,
            Proposal::GroupContextExtensions(_) => ProposalType::GROUP_CONTEXT_EXTENSIONS,
            #[cfg(all(
                feature = "by_ref_proposal",
                feature = "custom_proposal",
                feature = "self_remove_proposal"
            ))]
            Proposal::SelfRemove(_) => ProposalType::SELF_REMOVE,
            #[cfg(feature = "custom_proposal")]
            Proposal::Custom(c) => c.proposal_type,
        }
    }
}

#[derive(Clone, Debug, PartialEq)]
/// An enum that represents a borrowed version of [`Proposal`].
pub enum BorrowedProposal<'a> {
    Add(&'a AddProposal),
    #[cfg(feature = "by_ref_proposal")]
    Update(&'a UpdateProposal),
    Remove(&'a RemoveProposal),
    #[cfg(feature = "psk")]
    Psk(&'a PreSharedKeyProposal),
    ReInit(&'a ReInitProposal),
    ExternalInit(&'a ExternalInit),
    GroupContextExtensions(&'a ExtensionList),
    #[cfg(all(
        feature = "by_ref_proposal",
        feature = "custom_proposal",
        feature = "self_remove_proposal"
    ))]
    SelfRemove(&'a SelfRemoveProposal),
    #[cfg(feature = "custom_proposal")]
    Custom(&'a CustomProposal),
}

impl<'a> From<BorrowedProposal<'a>> for Proposal {
    fn from(value: BorrowedProposal<'a>) -> Self {
        match value {
            BorrowedProposal::Add(add) => Proposal::Add(alloc::boxed::Box::new(add.clone())),
            #[cfg(feature = "by_ref_proposal")]
            BorrowedProposal::Update(update) => Proposal::Update(update.clone()),
            BorrowedProposal::Remove(remove) => Proposal::Remove(remove.clone()),
            #[cfg(feature = "psk")]
            BorrowedProposal::Psk(psk) => Proposal::Psk(psk.clone()),
            BorrowedProposal::ReInit(reinit) => Proposal::ReInit(reinit.clone()),
            BorrowedProposal::ExternalInit(external) => Proposal::ExternalInit(external.clone()),
            BorrowedProposal::GroupContextExtensions(ext) => {
                Proposal::GroupContextExtensions(ext.clone())
            }
            #[cfg(all(
                feature = "by_ref_proposal",
                feature = "custom_proposal",
                feature = "self_remove_proposal"
            ))]
            BorrowedProposal::SelfRemove(self_remove) => Proposal::SelfRemove(self_remove.clone()),
            #[cfg(feature = "custom_proposal")]
            BorrowedProposal::Custom(custom) => Proposal::Custom(custom.clone()),
        }
    }
}

impl BorrowedProposal<'_> {
    pub fn proposal_type(&self) -> ProposalType {
        match self {
            BorrowedProposal::Add(_) => ProposalType::ADD,
            #[cfg(feature = "by_ref_proposal")]
            BorrowedProposal::Update(_) => ProposalType::UPDATE,
            BorrowedProposal::Remove(_) => ProposalType::REMOVE,
            #[cfg(feature = "psk")]
            BorrowedProposal::Psk(_) => ProposalType::PSK,
            BorrowedProposal::ReInit(_) => ProposalType::RE_INIT,
            BorrowedProposal::ExternalInit(_) => ProposalType::EXTERNAL_INIT,
            BorrowedProposal::GroupContextExtensions(_) => ProposalType::GROUP_CONTEXT_EXTENSIONS,
            #[cfg(all(
                feature = "by_ref_proposal",
                feature = "custom_proposal",
                feature = "self_remove_proposal"
            ))]
            BorrowedProposal::SelfRemove(_) => ProposalType::SELF_REMOVE,
            #[cfg(feature = "custom_proposal")]
            BorrowedProposal::Custom(c) => c.proposal_type,
        }
    }
}

impl<'a> From<&'a Proposal> for BorrowedProposal<'a> {
    fn from(p: &'a Proposal) -> Self {
        match p {
            Proposal::Add(p) => BorrowedProposal::Add(p),
            #[cfg(feature = "by_ref_proposal")]
            Proposal::Update(p) => BorrowedProposal::Update(p),
            Proposal::Remove(p) => BorrowedProposal::Remove(p),
            #[cfg(feature = "psk")]
            Proposal::Psk(p) => BorrowedProposal::Psk(p),
            Proposal::ReInit(p) => BorrowedProposal::ReInit(p),
            Proposal::ExternalInit(p) => BorrowedProposal::ExternalInit(p),
            Proposal::GroupContextExtensions(p) => BorrowedProposal::GroupContextExtensions(p),
            #[cfg(all(
                feature = "by_ref_proposal",
                feature = "custom_proposal",
                feature = "self_remove_proposal"
            ))]
            Proposal::SelfRemove(p) => BorrowedProposal::SelfRemove(p),
            #[cfg(feature = "custom_proposal")]
            Proposal::Custom(p) => BorrowedProposal::Custom(p),
        }
    }
}

impl<'a> From<&'a AddProposal> for BorrowedProposal<'a> {
    fn from(p: &'a AddProposal) -> Self {
        Self::Add(p)
    }
}

#[cfg(feature = "by_ref_proposal")]
impl<'a> From<&'a UpdateProposal> for BorrowedProposal<'a> {
    fn from(p: &'a UpdateProposal) -> Self {
        Self::Update(p)
    }
}

impl<'a> From<&'a RemoveProposal> for BorrowedProposal<'a> {
    fn from(p: &'a RemoveProposal) -> Self {
        Self::Remove(p)
    }
}

#[cfg(feature = "psk")]
impl<'a> From<&'a PreSharedKeyProposal> for BorrowedProposal<'a> {
    fn from(p: &'a PreSharedKeyProposal) -> Self {
        Self::Psk(p)
    }
}

impl<'a> From<&'a ReInitProposal> for BorrowedProposal<'a> {
    fn from(p: &'a ReInitProposal) -> Self {
        Self::ReInit(p)
    }
}

impl<'a> From<&'a ExternalInit> for BorrowedProposal<'a> {
    fn from(p: &'a ExternalInit) -> Self {
        Self::ExternalInit(p)
    }
}

impl<'a> From<&'a ExtensionList> for BorrowedProposal<'a> {
    fn from(p: &'a ExtensionList) -> Self {
        Self::GroupContextExtensions(p)
    }
}

#[cfg(all(
    feature = "by_ref_proposal",
    feature = "custom_proposal",
    feature = "self_remove_proposal"
))]
impl<'a> From<&'a SelfRemoveProposal> for BorrowedProposal<'a> {
    fn from(p: &'a SelfRemoveProposal) -> Self {
        Self::SelfRemove(p)
    }
}

#[cfg(feature = "custom_proposal")]
impl<'a> From<&'a CustomProposal> for BorrowedProposal<'a> {
    fn from(p: &'a CustomProposal) -> Self {
        Self::Custom(p)
    }
}

#[derive(Clone, Debug, PartialEq, MlsSize, MlsEncode, MlsDecode)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[repr(u8)]
pub(crate) enum ProposalOrRef {
    Proposal(Box<Proposal>) = 1u8,
    #[cfg(feature = "by_ref_proposal")]
    Reference(ProposalRef) = 2u8,
}

impl From<Proposal> for ProposalOrRef {
    fn from(proposal: Proposal) -> Self {
        Self::Proposal(Box::new(proposal))
    }
}

#[cfg(feature = "by_ref_proposal")]
impl From<ProposalRef> for ProposalOrRef {
    fn from(r: ProposalRef) -> Self {
        Self::Reference(r)
    }
}