Merging upstream version 1.70.0+dfsg2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 1034 insertions, 0 deletions

diff --git a/vendor/pem-rfc7468/src/decoder.rs b/vendor/pem-rfc7468/src/decoder.rs
new file mode 100644
index 000000000..8b8286a97
--- /dev/null
+++ b/vendor/pem-rfc7468/src/decoder.rs
@@ -0,0 +1,273 @@
+//! Decoder for PEM encapsulated data.
+//!
+//! From RFC 7468 Section 2:
+//!
+//! > Textual encoding begins with a line comprising "-----BEGIN ", a
+//! > label, and "-----", and ends with a line comprising "-----END ", a
+//! > label, and "-----".  Between these lines, or "encapsulation
+//! > boundaries", are base64-encoded data according to Section 4 of
+//! > [RFC 4648].
+//!
+//! [RFC 4648]: https://datatracker.ietf.org/doc/html/rfc4648
+
+use crate::{
+    grammar, Base64Decoder, Error, Result, BASE64_WRAP_WIDTH, POST_ENCAPSULATION_BOUNDARY,
+    PRE_ENCAPSULATION_BOUNDARY,
+};
+use core::str;
+
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+
+#[cfg(feature = "std")]
+use std::io;
+
+/// Decode a PEM document according to RFC 7468's "Strict" grammar.
+///
+/// On success, writes the decoded document into the provided buffer, returning
+/// the decoded label and the portion of the provided buffer containing the
+/// decoded message.
+pub fn decode<'i, 'o>(pem: &'i [u8], buf: &'o mut [u8]) -> Result<(&'i str, &'o [u8])> {
+    let mut decoder = Decoder::new(pem).map_err(|e| check_for_headers(pem, e))?;
+    let type_label = decoder.type_label();
+    let buf = buf
+        .get_mut(..decoder.remaining_len())
+        .ok_or(Error::Length)?;
+    let decoded = decoder.decode(buf).map_err(|e| check_for_headers(pem, e))?;
+
+    if decoder.base64.is_finished() {
+        Ok((type_label, decoded))
+    } else {
+        Err(Error::Length)
+    }
+}
+
+/// Decode a PEM document according to RFC 7468's "Strict" grammar, returning
+/// the result as a [`Vec`] upon success.
+#[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
+pub fn decode_vec(pem: &[u8]) -> Result<(&str, Vec<u8>)> {
+    let mut decoder = Decoder::new(pem).map_err(|e| check_for_headers(pem, e))?;
+    let type_label = decoder.type_label();
+    let mut buf = Vec::new();
+    decoder
+        .decode_to_end(&mut buf)
+        .map_err(|e| check_for_headers(pem, e))?;
+    Ok((type_label, buf))
+}
+
+/// Decode the encapsulation boundaries of a PEM document according to RFC 7468's "Strict" grammar.
+///
+/// On success, returning the decoded label.
+pub fn decode_label(pem: &[u8]) -> Result<&str> {
+    Ok(Encapsulation::try_from(pem)?.label())
+}
+
+/// Buffered PEM decoder.
+///
+/// Stateful buffered decoder type which decodes an input PEM document according
+/// to RFC 7468's "Strict" grammar.
+#[derive(Clone)]
+pub struct Decoder<'i> {
+    /// PEM type label.
+    type_label: &'i str,
+
+    /// Buffered Base64 decoder.
+    base64: Base64Decoder<'i>,
+}
+
+impl<'i> Decoder<'i> {
+    /// Create a new PEM [`Decoder`] with the default options.
+    ///
+    /// Uses the default 64-character line wrapping.
+    pub fn new(pem: &'i [u8]) -> Result<Self> {
+        Self::new_wrapped(pem, BASE64_WRAP_WIDTH)
+    }
+
+    /// Create a new PEM [`Decoder`] which wraps at the given line width.
+    pub fn new_wrapped(pem: &'i [u8], line_width: usize) -> Result<Self> {
+        let encapsulation = Encapsulation::try_from(pem)?;
+        let type_label = encapsulation.label();
+        let base64 = Base64Decoder::new_wrapped(encapsulation.encapsulated_text, line_width)?;
+        Ok(Self { type_label, base64 })
+    }
+
+    /// Get the PEM type label for the input document.
+    pub fn type_label(&self) -> &'i str {
+        self.type_label
+    }
+
+    /// Decode data into the provided output buffer.
+    ///
+    /// There must be at least as much remaining Base64 input to be decoded
+    /// in order to completely fill `buf`.
+    pub fn decode<'o>(&mut self, buf: &'o mut [u8]) -> Result<&'o [u8]> {
+        Ok(self.base64.decode(buf)?)
+    }
+
+    /// Decode all of the remaining data in the input buffer into `buf`.
+    #[cfg(feature = "alloc")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
+    pub fn decode_to_end<'o>(&mut self, buf: &'o mut Vec<u8>) -> Result<&'o [u8]> {
+        Ok(self.base64.decode_to_end(buf)?)
+    }
+
+    /// Get the decoded length of the remaining PEM data after Base64 decoding.
+    pub fn remaining_len(&self) -> usize {
+        self.base64.remaining_len()
+    }
+
+    /// Are we finished decoding the PEM input?
+    pub fn is_finished(&self) -> bool {
+        self.base64.is_finished()
+    }
+}
+
+impl<'i> From<Decoder<'i>> for Base64Decoder<'i> {
+    fn from(decoder: Decoder<'i>) -> Base64Decoder<'i> {
+        decoder.base64
+    }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+impl<'i> io::Read for Decoder<'i> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.base64.read(buf)
+    }
+
+    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
+        self.base64.read_to_end(buf)
+    }
+
+    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
+        self.base64.read_exact(buf)
+    }
+}
+
+/// PEM encapsulation parser.
+///
+/// This parser performs an initial pass over the data, locating the
+/// pre-encapsulation (`---BEGIN [...]---`) and post-encapsulation
+/// (`---END [...]`) boundaries while attempting to avoid branching
+/// on the potentially secret Base64-encoded data encapsulated between
+/// the two boundaries.
+///
+/// It only supports a single encapsulated message at present. Future work
+/// could potentially include extending it provide an iterator over a series
+/// of encapsulated messages.
+#[derive(Copy, Clone, Debug)]
+struct Encapsulation<'a> {
+    /// Type label extracted from the pre/post-encapsulation boundaries.
+    ///
+    /// From RFC 7468 Section 2:
+    ///
+    /// > The type of data encoded is labeled depending on the type label in
+    /// > the "-----BEGIN " line (pre-encapsulation boundary).  For example,
+    /// > the line may be "-----BEGIN CERTIFICATE-----" to indicate that the
+    /// > content is a PKIX certificate (see further below).  Generators MUST
+    /// > put the same label on the "-----END " line (post-encapsulation
+    /// > boundary) as the corresponding "-----BEGIN " line.  Labels are
+    /// > formally case-sensitive, uppercase, and comprised of zero or more
+    /// > characters; they do not contain consecutive spaces or hyphen-minuses,
+    /// > nor do they contain spaces or hyphen-minuses at either end.  Parsers
+    /// > MAY disregard the label in the post-encapsulation boundary instead of
+    /// > signaling an error if there is a label mismatch: some extant
+    /// > implementations require the labels to match; others do not.
+    label: &'a str,
+
+    /// Encapsulated text portion contained between the boundaries.
+    ///
+    /// This data should be encoded as Base64, however this type performs no
+    /// validation of it so it can be handled in constant-time.
+    encapsulated_text: &'a [u8],
+}
+
+impl<'a> Encapsulation<'a> {
+    /// Parse the type label and encapsulated text from between the
+    /// pre/post-encapsulation boundaries.
+    pub fn parse(data: &'a [u8]) -> Result<Self> {
+        // Strip the "preamble": optional text occurring before the pre-encapsulation boundary
+        let data = grammar::strip_preamble(data)?;
+
+        // Parse pre-encapsulation boundary (including label)
+        let data = data
+            .strip_prefix(PRE_ENCAPSULATION_BOUNDARY)
+            .ok_or(Error::PreEncapsulationBoundary)?;
+
+        let (label, body) = grammar::split_label(data).ok_or(Error::Label)?;
+
+        let mut body = match grammar::strip_trailing_eol(body).unwrap_or(body) {
+            [head @ .., b'-', b'-', b'-', b'-', b'-'] => head,
+            _ => return Err(Error::PreEncapsulationBoundary),
+        };
+
+        // Ensure body ends with a properly labeled post-encapsulation boundary
+        for &slice in [POST_ENCAPSULATION_BOUNDARY, label.as_bytes()].iter().rev() {
+            // Ensure the input ends with the post encapsulation boundary as
+            // well as a matching label
+            if !body.ends_with(slice) {
+                return Err(Error::PostEncapsulationBoundary);
+            }
+
+            let len = body.len().checked_sub(slice.len()).ok_or(Error::Length)?;
+            body = body.get(..len).ok_or(Error::PostEncapsulationBoundary)?;
+        }
+
+        let encapsulated_text =
+            grammar::strip_trailing_eol(body).ok_or(Error::PostEncapsulationBoundary)?;
+
+        Ok(Self {
+            label,
+            encapsulated_text,
+        })
+    }
+
+    /// Get the label parsed from the encapsulation boundaries.
+    pub fn label(self) -> &'a str {
+        self.label
+    }
+}
+
+impl<'a> TryFrom<&'a [u8]> for Encapsulation<'a> {
+    type Error = Error;
+
+    fn try_from(bytes: &'a [u8]) -> Result<Self> {
+        Self::parse(bytes)
+    }
+}
+
+/// Check for PEM headers in the input, as they are disallowed by RFC7468.
+///
+/// Returns `Error::HeaderDisallowed` if headers are encountered.
+fn check_for_headers(pem: &[u8], err: Error) -> Error {
+    if err == Error::Base64(base64ct::Error::InvalidEncoding)
+        && pem.iter().any(|&b| b == grammar::CHAR_COLON)
+    {
+        Error::HeaderDisallowed
+    } else {
+        err
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Encapsulation;
+
+    #[test]
+    fn pkcs8_example() {
+        let pem = include_bytes!("../tests/examples/pkcs8.pem");
+        let encapsulation = Encapsulation::parse(pem).unwrap();
+        assert_eq!(encapsulation.label, "PRIVATE KEY");
+
+        assert_eq!(
+            encapsulation.encapsulated_text,
+            &[
+                77, 67, 52, 67, 65, 81, 65, 119, 66, 81, 89, 68, 75, 50, 86, 119, 66, 67, 73, 69,
+                73, 66, 102, 116, 110, 72, 80, 112, 50, 50, 83, 101, 119, 89, 109, 109, 69, 111,
+                77, 99, 88, 56, 86, 119, 73, 52, 73, 72, 119, 97, 113, 100, 43, 57, 76, 70, 80,
+                106, 47, 49, 53, 101, 113, 70
+            ]
+        );
+    }
+}
diff --git a/vendor/pem-rfc7468/src/encoder.rs b/vendor/pem-rfc7468/src/encoder.rs
new file mode 100644
index 000000000..016e224c6
--- /dev/null
+++ b/vendor/pem-rfc7468/src/encoder.rs
@@ -0,0 +1,301 @@
+//! PEM encoder.
+
+use crate::{
+    grammar, Base64Encoder, Error, LineEnding, Result, BASE64_WRAP_WIDTH,
+    ENCAPSULATION_BOUNDARY_DELIMITER, POST_ENCAPSULATION_BOUNDARY, PRE_ENCAPSULATION_BOUNDARY,
+};
+use base64ct::{Base64, Encoding};
+use core::str;
+
+#[cfg(feature = "alloc")]
+use alloc::string::String;
+
+#[cfg(feature = "std")]
+use std::io;
+
+/// Compute the length of a PEM encoded document which encapsulates a
+/// Base64-encoded body including line endings every 64 characters.
+///
+/// The `input_len` parameter specifies the length of the raw input
+/// bytes prior to Base64 encoding.
+///
+/// Note that the current implementation of this function computes an upper
+/// bound of the length and the actual encoded document may be slightly shorter
+/// (typically 1-byte). Downstream consumers of this function should check the
+/// actual encoded length and potentially truncate buffers allocated using this
+/// function to estimate the encapsulated size.
+///
+/// Use [`encoded_len`] (when possible) to obtain a precise length.
+///
+/// ## Returns
+/// - `Ok(len)` on success
+/// - `Err(Error::Length)` on length overflow
+pub fn encapsulated_len(label: &str, line_ending: LineEnding, input_len: usize) -> Result<usize> {
+    encapsulated_len_wrapped(label, BASE64_WRAP_WIDTH, line_ending, input_len)
+}
+
+/// Compute the length of a PEM encoded document with the Base64 body
+/// line wrapped at the specified `width`.
+///
+/// This is the same as [`encapsulated_len`], which defaults to a width of 64.
+///
+/// Note that per [RFC7468 § 2] encoding PEM with any other wrap width besides
+/// 64 is technically non-compliant:
+///
+/// > Generators MUST wrap the base64-encoded lines so that each line
+/// > consists of exactly 64 characters except for the final line, which
+/// > will encode the remainder of the data (within the 64-character line
+/// > boundary)
+///
+/// [RFC7468 § 2]: https://datatracker.ietf.org/doc/html/rfc7468#section-2
+pub fn encapsulated_len_wrapped(
+    label: &str,
+    line_width: usize,
+    line_ending: LineEnding,
+    input_len: usize,
+) -> Result<usize> {
+    if line_width < 4 {
+        return Err(Error::Length);
+    }
+
+    let base64_len = input_len
+        .checked_mul(4)
+        .and_then(|n| n.checked_div(3))
+        .and_then(|n| n.checked_add(3))
+        .ok_or(Error::Length)?
+        & !3;
+
+    let base64_len_wrapped = base64_len_wrapped(base64_len, line_width, line_ending)?;
+    encapsulated_len_inner(label, line_ending, base64_len_wrapped)
+}
+
+/// Get the length of a PEM encoded document with the given bytes and label.
+///
+/// This function computes a precise length of the PEM encoding of the given
+/// `input` data.
+///
+/// ## Returns
+/// - `Ok(len)` on success
+/// - `Err(Error::Length)` on length overflow
+pub fn encoded_len(label: &str, line_ending: LineEnding, input: &[u8]) -> Result<usize> {
+    let base64_len = Base64::encoded_len(input);
+    let base64_len_wrapped = base64_len_wrapped(base64_len, BASE64_WRAP_WIDTH, line_ending)?;
+    encapsulated_len_inner(label, line_ending, base64_len_wrapped)
+}
+
+/// Encode a PEM document according to RFC 7468's "Strict" grammar.
+pub fn encode<'o>(
+    type_label: &str,
+    line_ending: LineEnding,
+    input: &[u8],
+    buf: &'o mut [u8],
+) -> Result<&'o str> {
+    let mut encoder = Encoder::new(type_label, line_ending, buf)?;
+    encoder.encode(input)?;
+    let encoded_len = encoder.finish()?;
+    let output = &buf[..encoded_len];
+
+    // Sanity check
+    debug_assert!(str::from_utf8(output).is_ok());
+
+    // Ensure `output` contains characters from the lower 7-bit ASCII set
+    if output.iter().fold(0u8, |acc, &byte| acc | (byte & 0x80)) == 0 {
+        // Use unchecked conversion to avoid applying UTF-8 checks to potentially
+        // secret PEM documents (and therefore introducing a potential timing
+        // sidechannel)
+        //
+        // SAFETY: contents of this buffer are controlled entirely by the encoder,
+        // which ensures the contents are always a valid (ASCII) subset of UTF-8.
+        // It's also additionally sanity checked by two assertions above to ensure
+        // the validity (with the always-on runtime check implemented in a
+        // constant time-ish manner.
+        #[allow(unsafe_code)]
+        Ok(unsafe { str::from_utf8_unchecked(output) })
+    } else {
+        Err(Error::CharacterEncoding)
+    }
+}
+
+/// Encode a PEM document according to RFC 7468's "Strict" grammar, returning
+/// the result as a [`String`].
+#[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
+pub fn encode_string(label: &str, line_ending: LineEnding, input: &[u8]) -> Result<String> {
+    let expected_len = encoded_len(label, line_ending, input)?;
+    let mut buf = vec![0u8; expected_len];
+    let actual_len = encode(label, line_ending, input, &mut buf)?.len();
+    debug_assert_eq!(expected_len, actual_len);
+    String::from_utf8(buf).map_err(|_| Error::CharacterEncoding)
+}
+
+/// Compute the encapsulated length of Base64 data of the given length.
+fn encapsulated_len_inner(
+    label: &str,
+    line_ending: LineEnding,
+    base64_len: usize,
+) -> Result<usize> {
+    [
+        PRE_ENCAPSULATION_BOUNDARY.len(),
+        label.as_bytes().len(),
+        ENCAPSULATION_BOUNDARY_DELIMITER.len(),
+        line_ending.len(),
+        base64_len,
+        line_ending.len(),
+        POST_ENCAPSULATION_BOUNDARY.len(),
+        label.as_bytes().len(),
+        ENCAPSULATION_BOUNDARY_DELIMITER.len(),
+        line_ending.len(),
+    ]
+    .into_iter()
+    .try_fold(0usize, |acc, len| acc.checked_add(len))
+    .ok_or(Error::Length)
+}
+
+/// Compute Base64 length line-wrapped at the specified width with the given
+/// line ending.
+fn base64_len_wrapped(
+    base64_len: usize,
+    line_width: usize,
+    line_ending: LineEnding,
+) -> Result<usize> {
+    base64_len
+        .saturating_sub(1)
+        .checked_div(line_width)
+        .and_then(|lines| lines.checked_mul(line_ending.len()))
+        .and_then(|len| len.checked_add(base64_len))
+        .ok_or(Error::Length)
+}
+
+/// Buffered PEM encoder.
+///
+/// Stateful buffered encoder type which encodes an input PEM document according
+/// to RFC 7468's "Strict" grammar.
+pub struct Encoder<'l, 'o> {
+    /// PEM type label.
+    type_label: &'l str,
+
+    /// Line ending used to wrap Base64.
+    line_ending: LineEnding,
+
+    /// Buffered Base64 encoder.
+    base64: Base64Encoder<'o>,
+}
+
+impl<'l, 'o> Encoder<'l, 'o> {
+    /// Create a new PEM [`Encoder`] with the default options which
+    /// writes output into the provided buffer.
+    ///
+    /// Uses the default 64-character line wrapping.
+    pub fn new(type_label: &'l str, line_ending: LineEnding, out: &'o mut [u8]) -> Result<Self> {
+        Self::new_wrapped(type_label, BASE64_WRAP_WIDTH, line_ending, out)
+    }
+
+    /// Create a new PEM [`Encoder`] which wraps at the given line width.
+    ///
+    /// Note that per [RFC7468 § 2] encoding PEM with any other wrap width besides
+    /// 64 is technically non-compliant:
+    ///
+    /// > Generators MUST wrap the base64-encoded lines so that each line
+    /// > consists of exactly 64 characters except for the final line, which
+    /// > will encode the remainder of the data (within the 64-character line
+    /// > boundary)
+    ///
+    /// This method is provided with the intended purpose of implementing the
+    /// OpenSSH private key format, which uses a non-standard wrap width of 70.
+    ///
+    /// [RFC7468 § 2]: https://datatracker.ietf.org/doc/html/rfc7468#section-2
+    pub fn new_wrapped(
+        type_label: &'l str,
+        line_width: usize,
+        line_ending: LineEnding,
+        mut out: &'o mut [u8],
+    ) -> Result<Self> {
+        grammar::validate_label(type_label.as_bytes())?;
+
+        for boundary_part in [
+            PRE_ENCAPSULATION_BOUNDARY,
+            type_label.as_bytes(),
+            ENCAPSULATION_BOUNDARY_DELIMITER,
+            line_ending.as_bytes(),
+        ] {
+            if out.len() < boundary_part.len() {
+                return Err(Error::Length);
+            }
+
+            let (part, rest) = out.split_at_mut(boundary_part.len());
+            out = rest;
+
+            part.copy_from_slice(boundary_part);
+        }
+
+        let base64 = Base64Encoder::new_wrapped(out, line_width, line_ending)?;
+
+        Ok(Self {
+            type_label,
+            line_ending,
+            base64,
+        })
+    }
+
+    /// Get the PEM type label used for this document.
+    pub fn type_label(&self) -> &'l str {
+        self.type_label
+    }
+
+    /// Encode the provided input data.
+    ///
+    /// This method can be called as many times as needed with any sized input
+    /// to write data encoded data into the output buffer, so long as there is
+    /// sufficient space in the buffer to handle the resulting Base64 encoded
+    /// data.
+    pub fn encode(&mut self, input: &[u8]) -> Result<()> {
+        self.base64.encode(input)?;
+        Ok(())
+    }
+
+    /// Borrow the inner [`Base64Encoder`].
+    pub fn base64_encoder(&mut self) -> &mut Base64Encoder<'o> {
+        &mut self.base64
+    }
+
+    /// Finish encoding PEM, writing the post-encapsulation boundary.
+    ///
+    /// On success, returns the total number of bytes written to the output
+    /// buffer.
+    pub fn finish(self) -> Result<usize> {
+        let (base64, mut out) = self.base64.finish_with_remaining()?;
+
+        for boundary_part in [
+            self.line_ending.as_bytes(),
+            POST_ENCAPSULATION_BOUNDARY,
+            self.type_label.as_bytes(),
+            ENCAPSULATION_BOUNDARY_DELIMITER,
+            self.line_ending.as_bytes(),
+        ] {
+            if out.len() < boundary_part.len() {
+                return Err(Error::Length);
+            }
+
+            let (part, rest) = out.split_at_mut(boundary_part.len());
+            out = rest;
+
+            part.copy_from_slice(boundary_part);
+        }
+
+        encapsulated_len_inner(self.type_label, self.line_ending, base64.len())
+    }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+impl<'l, 'o> io::Write for Encoder<'l, 'o> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.encode(buf)?;
+        Ok(buf.len())
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        // TODO(tarcieri): return an error if there's still data remaining in the buffer?
+        Ok(())
+    }
+}
diff --git a/vendor/pem-rfc7468/src/error.rs b/vendor/pem-rfc7468/src/error.rs
new file mode 100644
index 000000000..dd0ce87d5
--- /dev/null
+++ b/vendor/pem-rfc7468/src/error.rs
@@ -0,0 +1,108 @@
+//! Error types
+
+use core::fmt;
+
+/// Result type with the `pem-rfc7468` crate's [`Error`] type.
+pub type Result<T> = core::result::Result<T, Error>;
+
+/// PEM errors.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[non_exhaustive]
+pub enum Error {
+    /// Base64-related errors.
+    Base64(base64ct::Error),
+
+    /// Character encoding-related errors.
+    CharacterEncoding,
+
+    /// Errors in the encapsulated text (which aren't specifically Base64-related).
+    EncapsulatedText,
+
+    /// Header detected in the encapsulated text.
+    HeaderDisallowed,
+
+    /// Invalid label.
+    Label,
+
+    /// Invalid length.
+    Length,
+
+    /// "Preamble" (text before pre-encapsulation boundary) contains invalid data.
+    Preamble,
+
+    /// Errors in the pre-encapsulation boundary.
+    PreEncapsulationBoundary,
+
+    /// Errors in the post-encapsulation boundary.
+    PostEncapsulationBoundary,
+
+    /// Unexpected PEM type label.
+    UnexpectedTypeLabel {
+        /// Type label that was expected.
+        expected: &'static str,
+    },
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::Base64(err) => write!(f, "PEM Base64 error: {}", err),
+            Error::CharacterEncoding => f.write_str("PEM character encoding error"),
+            Error::EncapsulatedText => f.write_str("PEM error in encapsulated text"),
+            Error::HeaderDisallowed => f.write_str("PEM headers disallowed by RFC7468"),
+            Error::Label => f.write_str("PEM type label invalid"),
+            Error::Length => f.write_str("PEM length invalid"),
+            Error::Preamble => f.write_str("PEM preamble contains invalid data (NUL byte)"),
+            Error::PreEncapsulationBoundary => {
+                f.write_str("PEM error in pre-encapsulation boundary")
+            }
+            Error::PostEncapsulationBoundary => {
+                f.write_str("PEM error in post-encapsulation boundary")
+            }
+            Error::UnexpectedTypeLabel { expected } => {
+                write!(f, "unexpected PEM type label: expecting \"{}\"", expected)
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for Error {}
+
+impl From<base64ct::Error> for Error {
+    fn from(err: base64ct::Error) -> Error {
+        Error::Base64(err)
+    }
+}
+
+impl From<base64ct::InvalidLengthError> for Error {
+    fn from(_: base64ct::InvalidLengthError) -> Error {
+        Error::Length
+    }
+}
+
+impl From<core::str::Utf8Error> for Error {
+    fn from(_: core::str::Utf8Error) -> Error {
+        Error::CharacterEncoding
+    }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+impl From<Error> for std::io::Error {
+    fn from(err: Error) -> std::io::Error {
+        let kind = match err {
+            Error::Base64(err) => return err.into(), // Use existing conversion
+            Error::CharacterEncoding
+            | Error::EncapsulatedText
+            | Error::Label
+            | Error::Preamble
+            | Error::PreEncapsulationBoundary
+            | Error::PostEncapsulationBoundary => std::io::ErrorKind::InvalidData,
+            Error::Length => std::io::ErrorKind::UnexpectedEof,
+            _ => std::io::ErrorKind::Other,
+        };
+
+        std::io::Error::new(kind, err)
+    }
+}
diff --git a/vendor/pem-rfc7468/src/grammar.rs b/vendor/pem-rfc7468/src/grammar.rs
new file mode 100644
index 000000000..91085febb
--- /dev/null
+++ b/vendor/pem-rfc7468/src/grammar.rs
@@ -0,0 +1,232 @@
+//! Helper functions and rules for enforcing the ABNF grammar for
+//! RFC 7468-flavored PEM as described in Section 3.
+//!
+//! The grammar described below is intended to follow the "ABNF (Strict)"
+//! subset of the grammar as described in Section 3 Figure 3.
+
+use crate::{Error, Result, PRE_ENCAPSULATION_BOUNDARY};
+use core::str;
+
+/// NUL char
+pub(crate) const CHAR_NUL: u8 = 0x00;
+
+/// Horizontal tab
+pub(crate) const CHAR_HT: u8 = 0x09;
+
+/// Space
+pub(crate) const CHAR_SP: u8 = 0x20;
+
+/// Carriage return
+pub(crate) const CHAR_CR: u8 = 0x0d;
+
+/// Line feed
+pub(crate) const CHAR_LF: u8 = 0x0a;
+
+/// Colon ':'
+pub(crate) const CHAR_COLON: u8 = 0x3A;
+
+/// Any printable character except hyphen-minus, as defined in the
+/// 'labelchar' production in the RFC 7468 ABNF grammar
+pub(crate) fn is_labelchar(char: u8) -> bool {
+    matches!(char, 0x21..=0x2C | 0x2E..=0x7E)
+}
+
+/// Does the provided byte match a character allowed in a label?
+// TODO: allow hyphen-minus to match the 'label' production in the ABNF grammar
+pub(crate) fn is_allowed_in_label(char: u8) -> bool {
+    is_labelchar(char) || matches!(char, CHAR_HT | CHAR_SP)
+}
+
+/// Does the provided byte match the "WSP" ABNF production from Section 3?
+///
+/// > The common ABNF production WSP is congruent with "blank";
+/// > a new production W is used for "whitespace"
+pub(crate) fn is_wsp(char: u8) -> bool {
+    matches!(char, CHAR_HT | CHAR_SP)
+}
+
+/// Strip the "preamble", i.e. data that appears before the PEM
+/// pre-encapsulation boundary.
+///
+/// Presently no attempt is made to ensure the preamble decodes successfully
+/// under any particular character encoding. The only byte which is disallowed
+/// is the NUL byte. This restriction does not appear in RFC7468, but rather
+/// is inspired by the OpenSSL PEM decoder.
+///
+/// Returns a slice which starts at the beginning of the encapsulated text.
+///
+/// From RFC7468:
+/// > Data before the encapsulation boundaries are permitted, and
+/// > parsers MUST NOT malfunction when processing such data.
+pub(crate) fn strip_preamble(mut bytes: &[u8]) -> Result<&[u8]> {
+    if bytes.starts_with(PRE_ENCAPSULATION_BOUNDARY) {
+        return Ok(bytes);
+    }
+
+    while let Some((byte, remaining)) = bytes.split_first() {
+        match *byte {
+            CHAR_NUL => {
+                return Err(Error::Preamble);
+            }
+            CHAR_LF if remaining.starts_with(PRE_ENCAPSULATION_BOUNDARY) => {
+                return Ok(remaining);
+            }
+            _ => (),
+        }
+
+        bytes = remaining;
+    }
+
+    Err(Error::Preamble)
+}
+
+/// Strip a newline (`eol`) from the beginning of the provided byte slice.
+///
+/// The newline is considered mandatory and a decoding error will occur if it
+/// is not present.
+///
+/// From RFC 7468 Section 3:
+/// > lines are divided with CRLF, CR, or LF.
+pub(crate) fn strip_leading_eol(bytes: &[u8]) -> Option<&[u8]> {
+    match bytes {
+        [CHAR_LF, rest @ ..] => Some(rest),
+        [CHAR_CR, CHAR_LF, rest @ ..] => Some(rest),
+        [CHAR_CR, rest @ ..] => Some(rest),
+        _ => None,
+    }
+}
+
+/// Strip a newline (`eol`) from the end of the provided byte slice.
+///
+/// The newline is considered mandatory and a decoding error will occur if it
+/// is not present.
+///
+/// From RFC 7468 Section 3:
+/// > lines are divided with CRLF, CR, or LF.
+pub(crate) fn strip_trailing_eol(bytes: &[u8]) -> Option<&[u8]> {
+    match bytes {
+        [head @ .., CHAR_CR, CHAR_LF] => Some(head),
+        [head @ .., CHAR_LF] => Some(head),
+        [head @ .., CHAR_CR] => Some(head),
+        _ => None,
+    }
+}
+
+/// Split a slice beginning with a type label as located in an encapsulation
+/// boundary. Returns the label as a `&str`, and slice beginning with the
+/// encapsulated text with leading `-----` and newline removed.
+///
+/// This implementation follows the rules put forth in Section 2, which are
+/// stricter than those found in the ABNF grammar:
+///
+/// > Labels are formally case-sensitive, uppercase, and comprised of zero or more
+/// > characters; they do not contain consecutive spaces or hyphen-minuses,
+/// > nor do they contain spaces or hyphen-minuses at either end.
+///
+/// We apply a slightly stricter interpretation:
+/// - Labels MAY be empty
+/// - Non-empty labels MUST start with an upper-case letter: `'A'..='Z'`
+/// - The only allowable characters subsequently are `'A'..='Z'` or WSP.
+///   (NOTE: this is an overly strict initial implementation and should be relaxed)
+/// - Whitespace MUST NOT contain more than one consecutive WSP character
+// TODO(tarcieri): evaluate whether this is too strict; support '-'
+pub(crate) fn split_label(bytes: &[u8]) -> Option<(&str, &[u8])> {
+    let mut n = 0usize;
+
+    // TODO(tarcieri): handle hyphens in labels as well as spaces
+    let mut last_was_wsp = false;
+
+    for &char in bytes {
+        // Validate character
+        if is_labelchar(char) {
+            last_was_wsp = false;
+        } else if char == b'-' {
+            // Possible start of encapsulation boundary delimiter
+            break;
+        } else if n != 0 && is_wsp(char) {
+            // Repeated whitespace disallowed
+            if last_was_wsp {
+                return None;
+            }
+
+            last_was_wsp = true;
+        } else {
+            return None;
+        }
+
+        n = n.checked_add(1)?;
+    }
+
+    let (raw_label, rest) = bytes.split_at(n);
+    let label = str::from_utf8(raw_label).ok()?;
+
+    match rest {
+        [b'-', b'-', b'-', b'-', b'-', body @ ..] => Some((label, strip_leading_eol(body)?)),
+        _ => None,
+    }
+}
+
+/// Validate that the given bytes are allowed as a PEM type label, i.e. the
+/// label encoded in the `BEGIN` and `END` encapsulation boundaries.
+pub(crate) fn validate_label(label: &[u8]) -> Result<()> {
+    // TODO(tarcieri): handle hyphens in labels as well as spaces
+    let mut last_was_wsp = false;
+
+    for &char in label {
+        if !is_allowed_in_label(char) {
+            return Err(Error::Label);
+        }
+
+        if is_wsp(char) {
+            // Double sequential whitespace characters disallowed
+            if last_was_wsp {
+                return Err(Error::Label);
+            }
+
+            last_was_wsp = true;
+        } else {
+            last_was_wsp = false;
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Empty label is OK.
+    #[test]
+    fn split_label_empty() {
+        let (label, body) = split_label(b"-----\nBODY").unwrap();
+        assert_eq!(label, "");
+        assert_eq!(body, b"BODY");
+    }
+
+    /// Label containing text.
+    #[test]
+    fn split_label_with_text() {
+        let (label, body) = split_label(b"PRIVATE KEY-----\nBODY").unwrap();
+        assert_eq!(label, "PRIVATE KEY");
+        assert_eq!(body, b"BODY");
+    }
+
+    /// Reject labels containing repeated spaces
+    #[test]
+    fn split_label_with_repeat_wsp_is_err() {
+        assert!(split_label(b"PRIVATE  KEY-----\nBODY").is_none());
+    }
+
+    /// Basic validation of a label
+    #[test]
+    fn validate_private_key_label() {
+        assert_eq!(validate_label(b"PRIVATE KEY"), Ok(()));
+    }
+
+    /// Reject labels with double spaces
+    #[test]
+    fn validate_private_key_label_reject_double_space() {
+        assert_eq!(validate_label(b"PRIVATE  KEY"), Err(Error::Label));
+    }
+}
diff --git a/vendor/pem-rfc7468/src/lib.rs b/vendor/pem-rfc7468/src/lib.rs
new file mode 100644
index 000000000..15da39eed
--- /dev/null
+++ b/vendor/pem-rfc7468/src/lib.rs
@@ -0,0 +1,120 @@
+#![no_std]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+#![doc = include_str!("../README.md")]
+#![doc(
+    html_logo_url = "https://raw.githubusercontent.com/RustCrypto/meta/master/logo.svg",
+    html_favicon_url = "https://raw.githubusercontent.com/RustCrypto/meta/master/logo.svg"
+)]
+#![deny(unsafe_code)]
+#![warn(
+    clippy::integer_arithmetic,
+    clippy::panic,
+    clippy::panic_in_result_fn,
+    clippy::unwrap_used,
+    missing_docs,
+    rust_2018_idioms,
+    unused_qualifications
+)]
+
+//! # Usage
+//!
+#![cfg_attr(feature = "std", doc = " ```")]
+#![cfg_attr(not(feature = "std"), doc = " ```ignore")]
+//! # fn main() -> Result<(), Box<dyn std::error::Error>> {
+//! /// Example PEM document
+//! /// NOTE: do not actually put private key literals into your source code!!!
+//! let example_pem = "\
+//! -----BEGIN PRIVATE KEY-----
+//! MC4CAQAwBQYDK2VwBCIEIBftnHPp22SewYmmEoMcX8VwI4IHwaqd+9LFPj/15eqF
+//! -----END PRIVATE KEY-----
+//! ";
+//!
+//! // Decode PEM
+//! let (type_label, data) = pem_rfc7468::decode_vec(example_pem.as_bytes())?;
+//! assert_eq!(type_label, "PRIVATE KEY");
+//! assert_eq!(
+//!     data,
+//!     &[
+//!         48, 46, 2, 1, 0, 48, 5, 6, 3, 43, 101, 112, 4, 34, 4, 32, 23, 237, 156, 115, 233, 219,
+//!         100, 158, 193, 137, 166, 18, 131, 28, 95, 197, 112, 35, 130, 7, 193, 170, 157, 251,
+//!         210, 197, 62, 63, 245, 229, 234, 133
+//!     ]
+//! );
+//!
+//! // Encode PEM
+//! use pem_rfc7468::LineEnding;
+//! let encoded_pem = pem_rfc7468::encode_string(type_label, LineEnding::default(), &data)?;
+//! assert_eq!(&encoded_pem, example_pem);
+//! # Ok(())
+//! # }
+//! ```
+
+#[cfg(feature = "alloc")]
+#[macro_use]
+extern crate alloc;
+#[cfg(feature = "std")]
+extern crate std;
+
+mod decoder;
+mod encoder;
+mod error;
+mod grammar;
+
+pub use crate::{
+    decoder::{decode, decode_label, Decoder},
+    encoder::{encapsulated_len, encapsulated_len_wrapped, encode, encoded_len, Encoder},
+    error::{Error, Result},
+};
+pub use base64ct::LineEnding;
+
+#[cfg(feature = "alloc")]
+pub use crate::{decoder::decode_vec, encoder::encode_string};
+
+/// The pre-encapsulation boundary appears before the encapsulated text.
+///
+/// From RFC 7468 Section 2:
+/// > There are exactly five hyphen-minus (also known as dash) characters ("-")
+/// > on both ends of the encapsulation boundaries, no more, no less.
+const PRE_ENCAPSULATION_BOUNDARY: &[u8] = b"-----BEGIN ";
+
+/// The post-encapsulation boundary appears immediately after the encapsulated text.
+const POST_ENCAPSULATION_BOUNDARY: &[u8] = b"-----END ";
+
+/// Delimiter of encapsulation boundaries.
+const ENCAPSULATION_BOUNDARY_DELIMITER: &[u8] = b"-----";
+
+/// Width at which the Base64 body of RFC7468-compliant PEM is wrapped.
+///
+/// From [RFC7468 § 2]:
+///
+/// > Generators MUST wrap the base64-encoded lines so that each line
+/// > consists of exactly 64 characters except for the final line, which
+/// > will encode the remainder of the data (within the 64-character line
+/// > boundary), and they MUST NOT emit extraneous whitespace.  Parsers MAY
+/// > handle other line sizes.
+///
+/// [RFC7468 § 2]: https://datatracker.ietf.org/doc/html/rfc7468#section-2
+pub const BASE64_WRAP_WIDTH: usize = 64;
+
+/// Buffered Base64 decoder type.
+pub type Base64Decoder<'i> = base64ct::Decoder<'i, base64ct::Base64>;
+
+/// Buffered Base64 encoder type.
+pub type Base64Encoder<'o> = base64ct::Encoder<'o, base64ct::Base64>;
+
+/// Marker trait for types with an associated PEM type label.
+pub trait PemLabel {
+    /// Expected PEM type label for a given document, e.g. `"PRIVATE KEY"`
+    const PEM_LABEL: &'static str;
+
+    /// Validate that a given label matches the expected label.
+    fn validate_pem_label(actual: &str) -> Result<()> {
+        if Self::PEM_LABEL == actual {
+            Ok(())
+        } else {
+            Err(Error::UnexpectedTypeLabel {
+                expected: Self::PEM_LABEL,
+            })
+        }
+    }
+}