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//! Internal: Declare an Error type for tor-bytes
use std::borrow::Cow;
use thiserror::Error;
use tor_error::{into_internal, Bug};
/// Error type for decoding Tor objects from bytes.
//
// TODO(nickm): This error type could use a redesign: it doesn't do a good job
// of preserving context. At the least it should say what kind of object it
// found any given problem in.
#[derive(Error, Debug, Clone)]
#[non_exhaustive]
pub enum Error {
/// Tried to read something, but we didn't find enough bytes.
///
/// This can mean that the object is truncated, or that we need to
/// read more and try again, depending on the context in which it
/// was received.
#[error("Object truncated (or not fully present)")]
Truncated,
/// Called Reader::should_be_exhausted(), but found bytes anyway.
#[error("Extra bytes at end of object")]
ExtraneousBytes,
/// Invalid length value
#[error("Object length too large to represent as usize")]
BadLengthValue,
/// An attempt to parse an object failed for some reason related to its
/// contents.
#[deprecated(since = "0.6.2", note = "Use InvalidMessage instead.")]
#[error("Bad object: {0}")]
BadMessage(&'static str),
/// An attempt to parse an object failed for some reason related to its
/// contents.
#[error("Bad object: {0}")]
InvalidMessage(Cow<'static, str>),
/// A parsing error that should never happen.
///
/// We use this one in lieu of calling assert() and expect() and
/// unwrap() from within parsing code.
#[error("Internal error")]
Bug(#[from] tor_error::Bug),
}
impl PartialEq for Error {
fn eq(&self, other: &Self) -> bool {
use Error::*;
match (self, other) {
(Truncated, Truncated) => true,
(ExtraneousBytes, ExtraneousBytes) => true,
#[allow(deprecated)]
(BadMessage(a), BadMessage(b)) => a == b,
(InvalidMessage(a), InvalidMessage(b)) => a == b,
(BadLengthValue, BadLengthValue) => true,
// notably, this means that an internal error is equal to nothing, not even itself.
(_, _) => false,
}
}
}
/// Error type for encoding Tor objects to bytes.
#[derive(Error, Debug, Clone)]
#[non_exhaustive]
pub enum EncodeError {
/// We tried to encode an object with an attached length, but the length was
/// too large to encode in the available space.
#[error("Object length too large to encode")]
BadLengthValue,
/// A parsing error that should never happen.
///
/// We use this variant instead of calling assert() and expect() and
/// unwrap() from within encoding implementations.
#[error("Internal error")]
Bug(#[from] Bug),
}
impl EncodeError {
/// Converts this error into a [`Bug`]
///
/// Use when any encoding error is a bug.
//
// TODO: should this be a `From` impl or would that be too error-prone?
#[deprecated(note = "please use the `From<EncodeError>` trait for `Bug` instead")]
pub fn always_bug(self) -> Bug {
match self {
EncodeError::Bug(bug) => bug,
EncodeError::BadLengthValue => into_internal!("EncodingError")(self),
}
}
}
// This trait is used to convert any encoding error into a bug
impl From<EncodeError> for Bug {
fn from(error: EncodeError) -> Bug {
match error {
EncodeError::Bug(bug) => bug,
EncodeError::BadLengthValue => into_internal!("EncodingError")(error),
}
}
}