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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use neqo_common::{Decoder, Encoder};
use super::hframe::HFrameType;
use crate::{frames::reader::FrameDecoder, Error, Res};
pub type WebTransportFrameType = u64;
#[derive(PartialEq, Eq, Debug)]
pub enum WebTransportFrame {
CloseSession { error: u32, message: String },
}
impl WebTransportFrame {
/// The frame type for WebTransport `CLOSE_SESSION`, as defined in
/// [WebTransport over HTTP/3 (RFC 9297, Section 4.6)](https://datatracker.ietf.org/doc/html/rfc9297#section-4.6).
/// The value 0x2843 is assigned for `CLOSE_SESSION`.
const CLOSE_SESSION: WebTransportFrameType = 0x2843;
/// The maximum allowed message size for `CLOSE_SESSION` messages, as recommended
/// in [WebTransport over HTTP/3 (RFC 9297, Section 4.6)](https://datatracker.ietf.org/doc/html/rfc9297#section-4.6).
/// The value 1024 is used to limit the message size for security and interoperability.
const CLOSE_MAX_MESSAGE_SIZE: u64 = 1024;
pub fn encode(&self, enc: &mut Encoder) {
#[cfg(feature = "build-fuzzing-corpus")]
let start = enc.len();
enc.encode_varint(Self::CLOSE_SESSION);
let Self::CloseSession { error, message } = &self;
enc.encode_varint(4 + message.len() as u64);
enc.encode_uint(4, *error);
enc.encode(message.as_bytes());
#[cfg(feature = "build-fuzzing-corpus")]
neqo_common::write_item_to_fuzzing_corpus("wtframe", &enc.as_ref()[start..]);
}
}
impl FrameDecoder<Self> for WebTransportFrame {
#[cfg(feature = "build-fuzzing-corpus")]
const FUZZING_CORPUS: Option<&'static str> = Some("wtframe");
fn decode(frame_type: HFrameType, frame_len: u64, data: Option<&[u8]>) -> Res<Option<Self>> {
if let Some(payload) = data {
let mut dec = Decoder::from(payload);
if frame_type == HFrameType(Self::CLOSE_SESSION) {
if frame_len > Self::CLOSE_MAX_MESSAGE_SIZE + 4 {
return Err(Error::HttpMessage);
}
let error = dec.decode_uint().ok_or(Error::HttpMessage)?;
let Ok(message) = String::from_utf8(dec.decode_remainder().to_vec()) else {
return Err(Error::HttpMessage);
};
Ok(Some(Self::CloseSession { error, message }))
} else {
Ok(None)
}
} else {
Ok(None)
}
}
fn is_known_type(frame_type: HFrameType) -> bool {
frame_type == HFrameType(Self::CLOSE_SESSION)
}
}
#[cfg(test)]
#[cfg_attr(coverage_nightly, coverage(off))]
mod tests {
use super::{HFrameType, WebTransportFrame};
use crate::frames::reader::FrameDecoder as _;
#[test]
fn is_known_type_close_session() {
assert!(WebTransportFrame::is_known_type(HFrameType(
WebTransportFrame::CLOSE_SESSION
)));
}
#[test]
fn is_known_type_unknown() {
assert!(!WebTransportFrame::is_known_type(HFrameType(0x1234)));
assert!(!WebTransportFrame::is_known_type(HFrameType(0)));
}
#[test]
fn decode_close_session_too_large() {
// Message size exceeds CLOSE_MAX_MESSAGE_SIZE (1024) + 4 bytes for error code.
let large_message = vec![0u8; 1025];
let mut payload = vec![0, 0, 0, 0]; // 4-byte error code
payload.extend(&large_message);
let frame_len = payload.len() as u64;
let result = WebTransportFrame::decode(
HFrameType(WebTransportFrame::CLOSE_SESSION),
frame_len,
Some(&payload),
);
assert!(result.is_err());
}
#[test]
fn decode_close_session_at_limit() {
// Message size exactly at CLOSE_MAX_MESSAGE_SIZE (1024).
let message = vec![b'a'; 1024];
let mut payload = vec![0, 0, 0, 0]; // 4-byte error code
payload.extend(&message);
let frame_len = payload.len() as u64;
let result = WebTransportFrame::decode(
HFrameType(WebTransportFrame::CLOSE_SESSION),
frame_len,
Some(&payload),
);
assert!(result.is_ok());
}
}