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//! Error types.
pub use core::str::Utf8Error;
use crate::{Length, Tag};
use core::{convert::Infallible, fmt};
/// Result type.
pub type Result<T> = core::result::Result<T, Error>;
/// Error type
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub struct Error {
/// Kind of error
kind: ErrorKind,
/// Position inside of message where error occurred
position: Option<Length>,
}
impl Error {
/// Create a new [`Error`]
pub fn new(kind: ErrorKind, position: Length) -> Error {
Error {
kind,
position: Some(position),
}
}
/// Get the [`ErrorKind`] which occurred.
pub fn kind(self) -> ErrorKind {
self.kind
}
/// Get the position inside of the message where the error occurred.
pub fn position(self) -> Option<Length> {
self.position
}
/// For errors occurring inside of a nested message, extend the position
/// count by the location where the nested message occurs.
pub fn nested(self, nested_position: Length) -> Self {
// TODO(tarcieri): better handle length overflows occurring in this calculation?
let position = (nested_position + self.position.unwrap_or_default()).ok();
Self {
kind: self.kind,
position,
}
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.kind)?;
if let Some(pos) = self.position {
write!(f, " at DER byte {}", pos)?;
}
Ok(())
}
}
impl From<ErrorKind> for Error {
fn from(kind: ErrorKind) -> Error {
Error {
kind,
position: None,
}
}
}
impl From<core::convert::Infallible> for Error {
fn from(_: Infallible) -> Error {
unreachable!()
}
}
impl From<Utf8Error> for Error {
fn from(err: Utf8Error) -> Error {
Error {
kind: ErrorKind::Utf8(err),
position: None,
}
}
}
#[cfg(feature = "oid")]
impl From<const_oid::Error> for Error {
fn from(_: const_oid::Error) -> Error {
ErrorKind::Oid.into()
}
}
#[cfg(feature = "std")]
impl std::error::Error for ErrorKind {}
/// Error type.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
#[non_exhaustive]
pub enum ErrorKind {
/// Operation failed due to previous error
Failed,
/// Incorrect length for a given field
Length {
/// Tag type of the value being decoded
tag: Tag,
},
/// Message is not canonically encoded
Noncanonical,
/// Malformed OID
Oid,
/// Integer overflow occurred (library bug!)
Overflow,
/// Message is longer than this library's internal limits support
Overlength,
/// Undecoded trailing data at end of message
TrailingData {
/// Length of the decoded data
decoded: Length,
/// Total length of the remaining data left in the buffer
remaining: Length,
},
/// Unexpected end-of-message/nested field when decoding
Truncated,
/// Encoded message is shorter than the expected length
/// (i.e. an `Encodable` impl on a particular type has a buggy `encoded_len`)
Underlength {
/// Expected length
expected: Length,
/// Actual length
actual: Length,
},
/// Unexpected tag
UnexpectedTag {
/// Tag the decoder was expecting (if there is a single such tag).
///
/// `None` if multiple tags are expected/allowed, but the `actual` tag
/// does not match any of them.
expected: Option<Tag>,
/// Actual tag encountered in the message
actual: Tag,
},
/// Unknown/unsupported tag
UnknownTag {
/// Raw byte value of the tag
byte: u8,
},
/// UTF-8 errors
Utf8(Utf8Error),
/// Unexpected value
Value {
/// Tag of the unexpected value
tag: Tag,
},
}
impl ErrorKind {
/// Annotate an [`ErrorKind`] with context about where it occurred,
/// returning an error.
pub fn at(self, position: Length) -> Error {
Error::new(self, position)
}
}
impl fmt::Display for ErrorKind {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
ErrorKind::Failed => write!(f, "operation failed"),
ErrorKind::Length { tag } => write!(f, "incorrect length for {}", tag),
ErrorKind::Noncanonical => write!(f, "DER is not canonically encoded"),
ErrorKind::Oid => write!(f, "malformed OID"),
ErrorKind::Overflow => write!(f, "integer overflow"),
ErrorKind::Overlength => write!(f, "DER message is too long"),
ErrorKind::TrailingData { decoded, remaining } => {
write!(
f,
"trailing data at end of DER message: decoded {} bytes, {} bytes remaining",
decoded, remaining
)
}
ErrorKind::Truncated => write!(f, "DER message is truncated"),
ErrorKind::Underlength { expected, actual } => write!(
f,
"DER message too short: expected {}, got {}",
expected, actual
),
ErrorKind::UnexpectedTag { expected, actual } => {
write!(f, "unexpected ASN.1 DER tag: ")?;
if let Some(tag) = expected {
write!(f, "expected {}, ", tag)?;
}
write!(f, "got {}", actual)
}
ErrorKind::UnknownTag { byte } => {
write!(f, "unknown/unsupported ASN.1 DER tag: 0x{:02x}", byte)
}
ErrorKind::Utf8(e) => write!(f, "{}", e),
ErrorKind::Value { tag } => write!(f, "malformed ASN.1 DER value for {}", tag),
}
}
}