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use alloc::borrow::ToOwned;
use alloc::format;
use alloc::string::String;
use alloc::vec;
use alloc::vec::Vec;
use core::marker::PhantomData;
use core::ops::ControlFlow;
#[cfg(feature = "std")]
use std::fs::File;
#[cfg(feature = "std")]
use std::io::{self, ErrorKind};
use crate::base64;
/// Items that can be decoded from PEM data.
pub trait PemObject: Sized {
/// Decode the first section of this type from PEM contained in
/// a byte slice.
///
/// [`Error::NoItemsFound`] is returned if no such items are found.
fn from_pem_slice(pem: &[u8]) -> Result<Self, Error> {
Self::pem_slice_iter(pem)
.next()
.unwrap_or(Err(Error::NoItemsFound))
}
/// Iterate over all sections of this type from PEM contained in
/// a byte slice.
fn pem_slice_iter(pem: &[u8]) -> SliceIter<'_, Self> {
SliceIter {
current: pem,
_ty: PhantomData,
}
}
/// Decode the first section of this type from the PEM contents of the named file.
///
/// [`Error::NoItemsFound`] is returned if no such items are found.
#[cfg(feature = "std")]
fn from_pem_file(file_name: impl AsRef<std::path::Path>) -> Result<Self, Error> {
Self::pem_file_iter(file_name)?
.next()
.unwrap_or(Err(Error::NoItemsFound))
}
/// Iterate over all sections of this type from the PEM contents of the named file.
///
/// This reports errors in two phases:
///
/// - errors opening the file are reported from this function directly,
/// - errors reading from the file are reported from the returned iterator,
#[cfg(feature = "std")]
fn pem_file_iter(
file_name: impl AsRef<std::path::Path>,
) -> Result<ReadIter<io::BufReader<File>, Self>, Error> {
Ok(ReadIter::<_, Self> {
rd: io::BufReader::new(File::open(file_name).map_err(Error::Io)?),
_ty: PhantomData,
})
}
/// Decode the first section of this type from PEM read from an [`io::Read`].
#[cfg(feature = "std")]
fn from_pem_reader(rd: impl std::io::Read) -> Result<Self, Error> {
Self::pem_reader_iter(rd)
.next()
.unwrap_or(Err(Error::NoItemsFound))
}
/// Iterate over all sections of this type from PEM present in an [`io::Read`].
#[cfg(feature = "std")]
fn pem_reader_iter<R: std::io::Read>(rd: R) -> ReadIter<io::BufReader<R>, Self> {
ReadIter::<_, Self> {
rd: io::BufReader::new(rd),
_ty: PhantomData,
}
}
/// Conversion from a PEM [`SectionKind`] and body data.
///
/// This inspects `kind`, and if it matches this type's PEM section kind,
/// converts `der` into this type.
fn from_pem(kind: SectionKind, der: Vec<u8>) -> Option<Self>;
}
pub(crate) trait PemObjectFilter: PemObject + From<Vec<u8>> {
const KIND: SectionKind;
}
impl<T: PemObjectFilter + From<Vec<u8>>> PemObject for T {
fn from_pem(kind: SectionKind, der: Vec<u8>) -> Option<Self> {
match Self::KIND == kind {
true => Some(Self::from(der)),
false => None,
}
}
}
/// Extract and return all PEM sections by reading `rd`.
#[cfg(feature = "std")]
pub struct ReadIter<R, T> {
rd: R,
_ty: PhantomData<T>,
}
#[cfg(feature = "std")]
impl<R: io::BufRead, T: PemObject> ReadIter<R, T> {
/// Create a new iterator.
pub fn new(rd: R) -> Self {
Self {
rd,
_ty: PhantomData,
}
}
}
#[cfg(feature = "std")]
impl<R: io::BufRead, T: PemObject> Iterator for ReadIter<R, T> {
type Item = Result<T, Error>;
fn next(&mut self) -> Option<Self::Item> {
loop {
return match from_buf(&mut self.rd) {
Ok(Some((sec, item))) => match T::from_pem(sec, item) {
Some(res) => Some(Ok(res)),
None => continue,
},
Ok(None) => return None,
Err(err) => Some(Err(err)),
};
}
}
}
/// Iterator over all PEM sections in a `&[u8]` slice.
pub struct SliceIter<'a, T> {
current: &'a [u8],
_ty: PhantomData<T>,
}
impl<'a, T: PemObject> SliceIter<'a, T> {
/// Create a new iterator.
pub fn new(current: &'a [u8]) -> Self {
Self {
current,
_ty: PhantomData,
}
}
/// Returns the rest of the unparsed data.
///
/// This is the slice immediately following the most
/// recently returned item from `next()`.
#[doc(hidden)]
pub fn remainder(&self) -> &'a [u8] {
self.current
}
}
impl<T: PemObject> Iterator for SliceIter<'_, T> {
type Item = Result<T, Error>;
fn next(&mut self) -> Option<Self::Item> {
loop {
return match from_slice(self.current) {
Ok(Some(((sec, item), rest))) => {
self.current = rest;
match T::from_pem(sec, item) {
Some(res) => Some(Ok(res)),
None => continue,
}
}
Ok(None) => return None,
Err(err) => Some(Err(err)),
};
}
}
}
impl PemObject for (SectionKind, Vec<u8>) {
fn from_pem(kind: SectionKind, der: Vec<u8>) -> Option<Self> {
Some((kind, der))
}
}
/// Extract and decode the next supported PEM section from `input`
///
/// - `Ok(None)` is returned if there is no PEM section to read from `input`
/// - Syntax errors and decoding errors produce a `Err(...)`
/// - Otherwise each decoded section is returned with a `Ok(Some((..., remainder)))` where
/// `remainder` is the part of the `input` that follows the returned section
#[allow(clippy::type_complexity)]
fn from_slice(mut input: &[u8]) -> Result<Option<((SectionKind, Vec<u8>), &[u8])>, Error> {
let mut b64buf = Vec::with_capacity(1024);
let mut section = None::<(Vec<_>, Vec<_>)>;
loop {
let next_line = if let Some(index) = input
.iter()
.position(|byte| *byte == b'\n' || *byte == b'\r')
{
let (line, newline_plus_remainder) = input.split_at(index);
input = &newline_plus_remainder[1..];
Some(line)
} else {
None
};
match read(next_line, &mut section, &mut b64buf)? {
ControlFlow::Continue(()) => continue,
ControlFlow::Break(item) => return Ok(item.map(|item| (item, input))),
}
}
}
/// Extract and decode the next supported PEM section from `rd`.
///
/// - Ok(None) is returned if there is no PEM section read from `rd`.
/// - Underlying IO errors produce a `Err(...)`
/// - Otherwise each decoded section is returned with a `Ok(Some(...))`
#[cfg(feature = "std")]
pub fn from_buf(rd: &mut dyn io::BufRead) -> Result<Option<(SectionKind, Vec<u8>)>, Error> {
let mut b64buf = Vec::with_capacity(1024);
let mut section = None::<(Vec<_>, Vec<_>)>;
let mut line = Vec::with_capacity(80);
loop {
line.clear();
let len = read_until_newline(rd, &mut line).map_err(Error::Io)?;
let next_line = if len == 0 {
None
} else {
Some(line.as_slice())
};
match read(next_line, &mut section, &mut b64buf) {
Ok(ControlFlow::Break(opt)) => return Ok(opt),
Ok(ControlFlow::Continue(())) => continue,
Err(e) => return Err(e),
}
}
}
#[allow(clippy::type_complexity)]
fn read(
next_line: Option<&[u8]>,
section: &mut Option<(Vec<u8>, Vec<u8>)>,
b64buf: &mut Vec<u8>,
) -> Result<ControlFlow<Option<(SectionKind, Vec<u8>)>, ()>, Error> {
let line = if let Some(line) = next_line {
line
} else {
// EOF
return match section.take() {
Some((_, end_marker)) => Err(Error::MissingSectionEnd { end_marker }),
None => Ok(ControlFlow::Break(None)),
};
};
if line.starts_with(b"-----BEGIN ") {
let (mut trailer, mut pos) = (0, line.len());
for (i, &b) in line.iter().enumerate().rev() {
match b {
b'-' => {
trailer += 1;
pos = i;
}
b'\n' | b'\r' | b' ' => continue,
_ => break,
}
}
if trailer != 5 {
return Err(Error::IllegalSectionStart {
line: line.to_vec(),
});
}
let ty = &line[11..pos];
let mut end = Vec::with_capacity(10 + 4 + ty.len());
end.extend_from_slice(b"-----END ");
end.extend_from_slice(ty);
end.extend_from_slice(b"-----");
*section = Some((ty.to_owned(), end));
return Ok(ControlFlow::Continue(()));
}
if let Some((section_label, end_marker)) = section.as_ref() {
if line.starts_with(end_marker) {
let kind = match SectionKind::try_from(§ion_label[..]) {
Ok(kind) => kind,
// unhandled section: have caller try again
Err(()) => {
*section = None;
b64buf.clear();
return Ok(ControlFlow::Continue(()));
}
};
let mut der = vec![0u8; base64::decoded_length(b64buf.len())];
let der_len = match kind.secret() {
true => base64::decode_secret(b64buf, &mut der),
false => base64::decode_public(b64buf, &mut der),
}
.map_err(|err| Error::Base64Decode(format!("{err:?}")))?
.len();
der.truncate(der_len);
return Ok(ControlFlow::Break(Some((kind, der))));
}
}
if section.is_some() {
b64buf.extend(line);
}
Ok(ControlFlow::Continue(()))
}
/// A single recognised section in a PEM file.
#[non_exhaustive]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum SectionKind {
/// A DER-encoded x509 certificate.
///
/// Appears as "CERTIFICATE" in PEM files.
Certificate,
/// A DER-encoded Subject Public Key Info; as specified in RFC 7468.
///
/// Appears as "PUBLIC KEY" in PEM files.
PublicKey,
/// A DER-encoded plaintext RSA private key; as specified in PKCS #1/RFC 3447
///
/// Appears as "RSA PRIVATE KEY" in PEM files.
RsaPrivateKey,
/// A DER-encoded plaintext private key; as specified in PKCS #8/RFC 5958
///
/// Appears as "PRIVATE KEY" in PEM files.
PrivateKey,
/// A Sec1-encoded plaintext private key; as specified in RFC 5915
///
/// Appears as "EC PRIVATE KEY" in PEM files.
EcPrivateKey,
/// A Certificate Revocation List; as specified in RFC 5280
///
/// Appears as "X509 CRL" in PEM files.
Crl,
/// A Certificate Signing Request; as specified in RFC 2986
///
/// Appears as "CERTIFICATE REQUEST" in PEM files.
Csr,
/// An EchConfigList structure, as specified in
/// <https://www.ietf.org/archive/id/draft-farrell-tls-pemesni-05.html>.
///
/// Appears as "ECHCONFIG" in PEM files.
EchConfigList,
}
impl SectionKind {
fn secret(&self) -> bool {
match self {
Self::RsaPrivateKey | Self::PrivateKey | Self::EcPrivateKey => true,
Self::Certificate | Self::PublicKey | Self::Crl | Self::Csr | Self::EchConfigList => {
false
}
}
}
}
impl TryFrom<&[u8]> for SectionKind {
type Error = ();
fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
Ok(match value {
b"CERTIFICATE" => Self::Certificate,
b"PUBLIC KEY" => Self::PublicKey,
b"RSA PRIVATE KEY" => Self::RsaPrivateKey,
b"PRIVATE KEY" => Self::PrivateKey,
b"EC PRIVATE KEY" => Self::EcPrivateKey,
b"X509 CRL" => Self::Crl,
b"CERTIFICATE REQUEST" => Self::Csr,
b"ECHCONFIG" => Self::EchConfigList,
_ => return Err(()),
})
}
}
/// Errors that may arise when parsing the contents of a PEM file
#[non_exhaustive]
#[derive(Debug)]
pub enum Error {
/// a section is missing its "END marker" line
MissingSectionEnd {
/// the expected "END marker" line that was not found
end_marker: Vec<u8>,
},
/// syntax error found in the line that starts a new section
IllegalSectionStart {
/// line that contains the syntax error
line: Vec<u8>,
},
/// base64 decode error
Base64Decode(String),
/// I/O errors, from APIs that accept `std::io` types.
#[cfg(feature = "std")]
Io(io::Error),
/// No items found of desired type
NoItemsFound,
}
// Ported from https://github.com/rust-lang/rust/blob/91cfcb021935853caa06698b759c293c09d1e96a/library/std/src/io/mod.rs#L1990 and
// modified to look for our accepted newlines.
#[cfg(feature = "std")]
fn read_until_newline<R: io::BufRead + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> io::Result<usize> {
let mut read = 0;
loop {
let (done, used) = {
let available = match r.fill_buf() {
Ok(n) => n,
Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
Err(e) => return Err(e),
};
match available
.iter()
.copied()
.position(|b| b == b'\n' || b == b'\r')
{
Some(i) => {
buf.extend_from_slice(&available[..=i]);
(true, i + 1)
}
None => {
buf.extend_from_slice(available);
(false, available.len())
}
}
};
r.consume(used);
read += used;
if done || used == 0 {
return Ok(read);
}
}
}