dcsctp 0.1.11

An SCTP implementation for WebRTC Data Channels
Documentation 
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// Copyright 2025 The dcSCTP Authors
//
// Licensed 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
//
//     https://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 crate::packet::ChunkParseError;
use crate::packet::SerializableTlv;
use crate::packet::chunk::RawChunk;
use crate::packet::chunk::write_chunk_header;
use crate::packet::ensure;
use crate::packet::error_causes::ErrorCause;
use crate::packet::error_causes::error_cause_from_bytes;
use crate::packet::parameter::parameters_serialize_to;
use crate::packet::parameter::parameters_serialized_size;
use std::fmt;

pub(crate) const CHUNK_TYPE: u8 = 9;

/// Operation Error (ERROR) chunk
///
/// See <https://datatracker.ietf.org/doc/html/rfc9260#section-3.3.10>.
///
/// ```txt
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// |   Type = 9    |  Chunk Flags  |            Length             |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// \                                                               \
/// /                   one or more Error Causes                    /
/// \                                                               \
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// ```
#[derive(Debug, Default)]
pub struct ErrorChunk {
    pub error_causes: Vec<ErrorCause>,
}

impl TryFrom<RawChunk<'_>> for ErrorChunk {
    type Error = ChunkParseError;

    fn try_from(raw: RawChunk<'_>) -> Result<Self, ChunkParseError> {
        ensure!(raw.typ == CHUNK_TYPE, ChunkParseError::InvalidType);

        let error_causes = error_cause_from_bytes(raw.value)?;
        ensure!(!error_causes.is_empty(), ChunkParseError::InvalidLength);

        Ok(Self { error_causes })
    }
}

impl SerializableTlv for ErrorChunk {
    fn serialize_to(&self, output: &mut [u8]) {
        let value = write_chunk_header(CHUNK_TYPE, 0, self.value_size(), output);
        parameters_serialize_to(&self.error_causes, value);
    }

    fn value_size(&self) -> usize {
        parameters_serialized_size(&self.error_causes)
    }
}

impl fmt::Display for ErrorChunk {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "ERROR")
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::packet::unrecognized_chunk_error_cause::UnrecognizedChunkErrorCause;

    #[test]
    fn init_from_capture() {
        // ERROR chunk
        //    Chunk type: ERROR (9)
        //    Chunk flags: 0x00
        //    Chunk length: 12
        //    Unrecognized chunk type cause (Type: 73 (unknown))
        const BYTES: &[u8] =
            &[0x09, 0x00, 0x00, 0x0c, 0x00, 0x06, 0x00, 0x08, 0x49, 0x00, 0x00, 0x04];
        let error = ErrorChunk::try_from(RawChunk::from_bytes(BYTES).unwrap().0).unwrap();
        assert_eq!(error.error_causes.len(), 1);
        match &error.error_causes[0] {
            ErrorCause::UnrecognizedChunk(c) => {
                assert_eq!(c.chunk, vec![73, 0, 0, 4]);
            }
            _ => unreachable!(),
        }
    }

    #[test]
    fn serialize_and_deserialize() {
        let chunk = ErrorChunk {
            error_causes: vec![ErrorCause::UnrecognizedChunk(UnrecognizedChunkErrorCause {
                chunk: vec![1, 2, 3, 4],
            })],
        };

        let mut serialized = vec![0; chunk.serialized_size()];
        chunk.serialize_to(&mut serialized);
        let parsed = ErrorChunk::try_from(RawChunk::from_bytes(&serialized).unwrap().0).unwrap();
        match &parsed.error_causes[0] {
            ErrorCause::UnrecognizedChunk(c) => {
                assert_eq!(c.chunk, vec![1, 2, 3, 4]);
            }
            _ => unreachable!(),
        }
    }
}