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//! # Message framing
//!
//! This module contains framing-related operations for MLS messages, including validation operations.
//! The general structure of the framing process in OpenMLS closely mirrors the
//! one described in Section 7 of the MLS specification. It can be visualized as follows:
//!
//! ```text
//! Proposal Commit Application Data
//! | | |
//! +--------------+--------------+
//! |
//! V
//! FramedContent
//! | | -.
//! | | |
//! +--------+ | |
//! | | |
//! V | +-- Asymmetric
//! FramedContentAuthData | | Sign / Verify
//! | | |
//! +--------+ | |
//! | | |
//! V V -'
//! AuthenticatedContent
//! | -.
//! | |
//! | |
//! +--------+--------+ +-- Symmetric
//! | | | Protect / Unprotect
//! V V |
//! Welcome KeyPackage GroupInfo PublicMessage PrivateMessage -'
//! | | | | |
//! | | | | |
//! +----------+----------+----+--------+-----------------+
//! |
//! V
//! MLSMessage
//! ```
//!
//! - [`MlsMessageIn`]/[`MlsMessageOut`]: Unified message type for incoming & outgoing MLS messages
//! - [`ApplicationMessage`]: Application message received through a [`ProcessedMessage`]
use serde::{Deserialize, Serialize};
use tls_codec::*;
use crate::{
ciphersuite::*,
credentials::*,
group::*,
messages::{proposals::*, *},
schedule::{message_secrets::*, *},
};
pub(crate) mod codec;
pub(crate) mod message_in;
pub(crate) mod message_out;
pub(crate) mod mls_auth_content;
pub(crate) mod mls_auth_content_in;
pub(crate) mod mls_content;
pub(crate) mod mls_content_in;
pub(crate) mod private_message;
pub(crate) mod private_message_in;
pub(crate) mod public_message;
pub(crate) mod public_message_in;
pub(crate) mod sender;
pub(crate) mod validation;
pub(crate) use errors::*;
#[cfg(test)]
pub(crate) use mls_auth_content::*;
#[cfg(test)]
pub(crate) use mls_auth_content_in::*;
#[cfg(test)]
pub(crate) use mls_content::*;
#[cfg(test)]
pub(crate) use mls_content_in::*;
// Crate
pub(crate) use sender::*;
// Public
pub mod errors;
pub use message_in::*;
pub use message_out::*;
pub use private_message::*;
pub use private_message_in::*;
pub use public_message::*;
pub use public_message_in::*;
pub use sender::*;
pub use validation::*;
// Tests
#[cfg(test)]
pub(crate) mod test_framing;
/// Wire format of MLS messages.
///
/// // draft-ietf-mls-protocol-17
/// | Value | Name | Recommended | Reference |
/// |-----------------|--------------------------|-------------|-----------|
/// | 0x0000 | RESERVED | N/A | RFC XXXX |
/// | 0x0001 | mls_plaintext | Y | RFC XXXX |
/// | 0x0002 | mls_ciphertext | Y | RFC XXXX |
/// | 0x0003 | mls_welcome | Y | RFC XXXX |
/// | 0x0004 | mls_group_info | Y | RFC XXXX |
/// | 0x0005 | mls_key_package | Y | RFC XXXX |
/// | 0xf000 - 0xffff | Reserved for Private Use | N/A | RFC XXXX |
#[derive(
PartialEq, Eq, Clone, Copy, Debug, Serialize, Deserialize, TlsDeserialize, TlsSerialize, TlsSize,
)]
#[repr(u16)]
pub enum WireFormat {
/// Plaintext message
PublicMessage = 1,
/// Encrypted message
PrivateMessage = 2,
/// Welcome message
Welcome = 3,
/// Group information
GroupInfo = 4,
/// KeyPackage
KeyPackage = 5,
}
/// This struct is used to group common framing parameters
/// in order to reduce the number of arguments in function calls.
#[derive(Clone, Copy, PartialEq, Debug)]
pub(crate) struct FramingParameters<'a> {
aad: &'a [u8],
wire_format: WireFormat,
}
impl<'a> FramingParameters<'a> {
pub(crate) fn new(aad: &'a [u8], wire_format: impl Into<WireFormat>) -> Self {
Self {
aad,
wire_format: wire_format.into(),
}
}
pub(crate) fn aad(&self) -> &'a [u8] {
self.aad
}
pub(crate) fn wire_format(&self) -> WireFormat {
self.wire_format
}
}
/// ```c
/// // draft-ietf-mls-protocol-17
/// enum {
/// reserved(0),
/// application(1),
/// proposal(2),
/// commit(3),
/// (255)
/// } ContentType;
/// ```
#[derive(
PartialEq, Eq, Clone, Copy, Debug, Serialize, Deserialize, TlsDeserialize, TlsSerialize, TlsSize,
)]
#[repr(u8)]
pub enum ContentType {
/// Application message
Application = 1,
/// Proposal
Proposal = 2,
/// Commit
Commit = 3,
}
impl TryFrom<u8> for ContentType {
type Error = tls_codec::Error;
fn try_from(value: u8) -> Result<Self, tls_codec::Error> {
match value {
1 => Ok(ContentType::Application),
2 => Ok(ContentType::Proposal),
3 => Ok(ContentType::Commit),
_ => Err(tls_codec::Error::DecodingError(format!(
"{value} is not a valid content type"
))),
}
}
}
impl ContentType {
/// Returns `true` if this is a handshake message and `false` otherwise.
pub(crate) fn is_handshake_message(&self) -> bool {
self == &ContentType::Proposal || self == &ContentType::Commit
}
}