rustls_pki_types/
pem.rs

1use alloc::format;
2use alloc::string::String;
3use alloc::vec;
4use alloc::vec::Vec;
5use core::fmt;
6use core::marker::PhantomData;
7use core::ops::ControlFlow;
8#[cfg(feature = "std")]
9use std::fs::File;
10#[cfg(feature = "std")]
11use std::io::{self, ErrorKind};
12
13use crate::base64;
14
15/// Items that can be decoded from PEM data.
16pub trait PemObject: Sized {
17    /// Decode the first section of this type from PEM contained in
18    /// a byte slice.
19    ///
20    /// [`Error::NoItemsFound`] is returned if no such items are found.
21    fn from_pem_slice(pem: &[u8]) -> Result<Self, Error> {
22        Self::pem_slice_iter(pem)
23            .next()
24            .unwrap_or(Err(Error::NoItemsFound))
25    }
26
27    /// Iterate over all sections of this type from PEM contained in
28    /// a byte slice.
29    fn pem_slice_iter(pem: &[u8]) -> SliceIter<'_, Self> {
30        SliceIter::new(pem)
31    }
32
33    /// Decode the first section of this type from the PEM contents of the named file.
34    ///
35    /// [`Error::NoItemsFound`] is returned if no such items are found.
36    #[cfg(feature = "std")]
37    fn from_pem_file(file_name: impl AsRef<std::path::Path>) -> Result<Self, Error> {
38        Self::pem_file_iter(file_name)?
39            .next()
40            .unwrap_or(Err(Error::NoItemsFound))
41    }
42
43    /// Iterate over all sections of this type from the PEM contents of the named file.
44    ///
45    /// This reports errors in two phases:
46    ///
47    /// - errors opening the file are reported from this function directly,
48    /// - errors reading from the file are reported from the returned iterator,
49    #[cfg(feature = "std")]
50    fn pem_file_iter(
51        file_name: impl AsRef<std::path::Path>,
52    ) -> Result<ReadIter<io::BufReader<File>, Self>, Error> {
53        Ok(ReadIter::new(io::BufReader::new(
54            File::open(file_name).map_err(Error::Io)?,
55        )))
56    }
57
58    /// Decode the first section of this type from PEM read from an [`io::Read`].
59    #[cfg(feature = "std")]
60    fn from_pem_reader(rd: impl io::Read) -> Result<Self, Error> {
61        Self::pem_reader_iter(rd)
62            .next()
63            .unwrap_or(Err(Error::NoItemsFound))
64    }
65
66    /// Iterate over all sections of this type from PEM present in an [`io::Read`].
67    #[cfg(feature = "std")]
68    fn pem_reader_iter<R: io::Read>(rd: R) -> ReadIter<io::BufReader<R>, Self> {
69        ReadIter::new(io::BufReader::new(rd))
70    }
71
72    /// Conversion from a PEM [`SectionKind`] and body data.
73    ///
74    /// This inspects `kind`, and if it matches this type's PEM section kind,
75    /// converts `der` into this type.
76    fn from_pem(kind: SectionKind, der: Vec<u8>) -> Option<Self>;
77}
78
79pub(crate) trait PemObjectFilter: PemObject + From<Vec<u8>> {
80    const KIND: SectionKind;
81}
82
83impl<T: PemObjectFilter + From<Vec<u8>>> PemObject for T {
84    fn from_pem(kind: SectionKind, der: Vec<u8>) -> Option<Self> {
85        match Self::KIND == kind {
86            true => Some(Self::from(der)),
87            false => None,
88        }
89    }
90}
91
92/// Extract and return all PEM sections by reading `rd`.
93#[cfg(feature = "std")]
94pub struct ReadIter<R, T> {
95    rd: R,
96    _ty: PhantomData<T>,
97    line: Vec<u8>,
98    b64_buf: Vec<u8>,
99    /// Used to fuse the iterator on I/O errors
100    done: bool,
101}
102
103#[cfg(feature = "std")]
104impl<R: io::BufRead, T: PemObject> ReadIter<R, T> {
105    /// Create a new iterator.
106    pub fn new(rd: R) -> Self {
107        Self {
108            rd,
109            _ty: PhantomData,
110            line: Vec::with_capacity(80),
111            b64_buf: Vec::with_capacity(1024),
112            done: false,
113        }
114    }
115}
116
117#[cfg(feature = "std")]
118impl<R: io::BufRead, T: PemObject> Iterator for ReadIter<R, T> {
119    type Item = Result<T, Error>;
120
121    fn next(&mut self) -> Option<Self::Item> {
122        if self.done {
123            return None;
124        }
125
126        loop {
127            self.b64_buf.clear();
128            return match from_buf_inner(&mut self.rd, &mut self.line, &mut self.b64_buf) {
129                Ok(Some((sec, item))) => match T::from_pem(sec, item) {
130                    Some(res) => Some(Ok(res)),
131                    None => continue,
132                },
133                Ok(None) => return None,
134                Err(Error::Io(error)) => {
135                    self.done = true;
136                    Some(Err(Error::Io(error)))
137                }
138                Err(err) => Some(Err(err)),
139            };
140        }
141    }
142}
143
144/// Iterator over all PEM sections in a `&[u8]` slice.
145pub struct SliceIter<'a, T> {
146    current: &'a [u8],
147    _ty: PhantomData<T>,
148    b64_buf: Vec<u8>,
149}
150
151impl<'a, T: PemObject> SliceIter<'a, T> {
152    /// Create a new iterator.
153    pub fn new(current: &'a [u8]) -> Self {
154        Self {
155            current,
156            _ty: PhantomData,
157            b64_buf: Vec::with_capacity(1024),
158        }
159    }
160
161    /// Extract and decode the next supported PEM section from `input`
162    ///
163    /// - `Ok(None)` is returned if there is no PEM section to read from `input`
164    /// - Syntax errors and decoding errors produce a `Err(...)`
165    /// - Otherwise each decoded section is returned with a `Ok(Some((..., remainder)))` where
166    ///   `remainder` is the part of the `input` that follows the returned section
167    fn read_section(&mut self) -> Result<Option<(SectionKind, Vec<u8>)>, Error> {
168        self.b64_buf.clear();
169        let mut section = None;
170        loop {
171            let next_line = if let Some(index) = self
172                .current
173                .iter()
174                .position(|byte| *byte == b'\n' || *byte == b'\r')
175            {
176                let (line, newline_plus_remainder) = self.current.split_at(index);
177                self.current = &newline_plus_remainder[1..];
178                Some(line)
179            } else if !self.current.is_empty() {
180                let next_line = self.current;
181                self.current = &[];
182                Some(next_line)
183            } else {
184                None
185            };
186
187            match read(next_line, &mut section, &mut self.b64_buf)? {
188                ControlFlow::Continue(()) => continue,
189                ControlFlow::Break(item) => return Ok(item),
190            }
191        }
192    }
193
194    /// Returns the rest of the unparsed data.
195    ///
196    /// This is the slice immediately following the most
197    /// recently returned item from `next()`.
198    #[doc(hidden)]
199    pub fn remainder(&self) -> &'a [u8] {
200        self.current
201    }
202}
203
204impl<T: PemObject> Iterator for SliceIter<'_, T> {
205    type Item = Result<T, Error>;
206
207    fn next(&mut self) -> Option<Self::Item> {
208        loop {
209            return match self.read_section() {
210                Ok(Some((sec, item))) => match T::from_pem(sec, item) {
211                    Some(res) => Some(Ok(res)),
212                    None => continue,
213                },
214                Ok(None) => return None,
215                Err(err) => Some(Err(err)),
216            };
217        }
218    }
219}
220
221impl PemObject for (SectionKind, Vec<u8>) {
222    fn from_pem(kind: SectionKind, der: Vec<u8>) -> Option<Self> {
223        Some((kind, der))
224    }
225}
226
227/// Extract and decode the next supported PEM section from `rd`.
228///
229/// - Ok(None) is returned if there is no PEM section read from `rd`.
230/// - Underlying IO errors produce a `Err(...)`
231/// - Otherwise each decoded section is returned with a `Ok(Some(...))`
232#[cfg(feature = "std")]
233pub fn from_buf(rd: &mut dyn io::BufRead) -> Result<Option<(SectionKind, Vec<u8>)>, Error> {
234    let mut b64buf = Vec::with_capacity(1024);
235    let mut line = Vec::with_capacity(80);
236    from_buf_inner(rd, &mut line, &mut b64buf)
237}
238
239#[cfg(feature = "std")]
240fn from_buf_inner(
241    rd: &mut dyn io::BufRead,
242    line: &mut Vec<u8>,
243    b64buf: &mut Vec<u8>,
244) -> Result<Option<(SectionKind, Vec<u8>)>, Error> {
245    let mut section = None;
246    loop {
247        line.clear();
248        let len = read_until_newline(rd, line).map_err(Error::Io)?;
249
250        let next_line = if len == 0 {
251            None
252        } else {
253            Some(line.as_slice())
254        };
255
256        match read(next_line, &mut section, b64buf) {
257            Ok(ControlFlow::Break(opt)) => return Ok(opt),
258            Ok(ControlFlow::Continue(())) => continue,
259            Err(e) => return Err(e),
260        }
261    }
262}
263
264#[allow(clippy::type_complexity)]
265fn read(
266    next_line: Option<&[u8]>,
267    section: &mut Option<SectionLabel>,
268    b64buf: &mut Vec<u8>,
269) -> Result<ControlFlow<Option<(SectionKind, Vec<u8>)>, ()>, Error> {
270    let line = if let Some(line) = next_line {
271        line
272    } else {
273        // EOF
274        return match section.take() {
275            Some(label) => Err(Error::MissingSectionEnd {
276                end_marker: label.as_ref().to_vec(),
277            }),
278            None => Ok(ControlFlow::Break(None)),
279        };
280    };
281
282    if line.starts_with(b"-----BEGIN ") {
283        let (mut trailer, mut pos) = (0, line.len());
284        for (i, &b) in line.iter().enumerate().rev() {
285            match b {
286                b'-' => {
287                    trailer += 1;
288                    pos = i;
289                }
290                b'\n' | b'\r' | b' ' => continue,
291                _ => break,
292            }
293        }
294
295        if trailer != 5 {
296            return Err(Error::IllegalSectionStart {
297                line: line.to_vec(),
298            });
299        }
300
301        let ty = &line[11..pos];
302        *section = Some(SectionLabel::from(ty));
303        return Ok(ControlFlow::Continue(()));
304    }
305
306    if let Some(label) = section.as_ref() {
307        if label.is_end(line) {
308            let kind = match label {
309                SectionLabel::Known(kind) => *kind,
310                // unhandled section: have caller try again
311                SectionLabel::Unknown(_) => {
312                    *section = None;
313                    b64buf.clear();
314                    return Ok(ControlFlow::Continue(()));
315                }
316            };
317
318            let mut der = vec![0u8; base64::decoded_length(b64buf.len())];
319            let der_len = match kind.secret() {
320                true => base64::decode_secret(b64buf, &mut der),
321                false => base64::decode_public(b64buf, &mut der),
322            }
323            .map_err(|err| Error::Base64Decode(format!("{err:?}")))?
324            .len();
325
326            der.truncate(der_len);
327
328            return Ok(ControlFlow::Break(Some((kind, der))));
329        }
330    }
331
332    if section.is_some() {
333        b64buf.extend(line);
334    }
335
336    Ok(ControlFlow::Continue(()))
337}
338
339enum SectionLabel {
340    Known(SectionKind),
341    Unknown(Vec<u8>),
342}
343
344impl SectionLabel {
345    fn is_end(&self, line: &[u8]) -> bool {
346        let rest = match line.strip_prefix(b"-----END ") {
347            Some(rest) => rest,
348            None => return false,
349        };
350
351        let ty = match self {
352            Self::Known(kind) => kind.as_slice(),
353            Self::Unknown(ty) => ty,
354        };
355
356        let rest = match rest.strip_prefix(ty) {
357            Some(rest) => rest,
358            None => return false,
359        };
360
361        rest.starts_with(b"-----")
362    }
363}
364
365impl From<&[u8]> for SectionLabel {
366    fn from(value: &[u8]) -> Self {
367        match SectionKind::try_from(value) {
368            Ok(kind) => Self::Known(kind),
369            Err(_) => Self::Unknown(value.to_vec()),
370        }
371    }
372}
373
374impl AsRef<[u8]> for SectionLabel {
375    fn as_ref(&self) -> &[u8] {
376        match self {
377            Self::Known(kind) => kind.as_slice(),
378            Self::Unknown(ty) => ty,
379        }
380    }
381}
382
383/// A single recognised section in a PEM file.
384#[non_exhaustive]
385#[derive(Clone, Copy, Debug, PartialEq)]
386pub enum SectionKind {
387    /// A DER-encoded x509 certificate.
388    ///
389    /// Appears as "CERTIFICATE" in PEM files.
390    Certificate,
391
392    /// A DER-encoded Subject Public Key Info; as specified in RFC 7468.
393    ///
394    /// Appears as "PUBLIC KEY" in PEM files.
395    PublicKey,
396
397    /// A DER-encoded plaintext RSA private key; as specified in PKCS #1/RFC 3447
398    ///
399    /// Appears as "RSA PRIVATE KEY" in PEM files.
400    RsaPrivateKey,
401
402    /// A DER-encoded plaintext private key; as specified in PKCS #8/RFC 5958
403    ///
404    /// Appears as "PRIVATE KEY" in PEM files.
405    PrivateKey,
406
407    /// A Sec1-encoded plaintext private key; as specified in RFC 5915
408    ///
409    /// Appears as "EC PRIVATE KEY" in PEM files.
410    EcPrivateKey,
411
412    /// A Certificate Revocation List; as specified in RFC 5280
413    ///
414    /// Appears as "X509 CRL" in PEM files.
415    Crl,
416
417    /// A Certificate Signing Request; as specified in RFC 2986
418    ///
419    /// Appears as "CERTIFICATE REQUEST" in PEM files.
420    Csr,
421
422    /// An EchConfigList structure, as specified in
423    /// <https://www.ietf.org/archive/id/draft-farrell-tls-pemesni-05.html>.
424    ///
425    /// Appears as "ECHCONFIG" in PEM files.
426    EchConfigList,
427}
428
429impl SectionKind {
430    const fn secret(&self) -> bool {
431        match self {
432            Self::RsaPrivateKey | Self::PrivateKey | Self::EcPrivateKey => true,
433            Self::Certificate | Self::PublicKey | Self::Crl | Self::Csr | Self::EchConfigList => {
434                false
435            }
436        }
437    }
438
439    fn as_slice(&self) -> &'static [u8] {
440        match self {
441            Self::Certificate => b"CERTIFICATE",
442            Self::PublicKey => b"PUBLIC KEY",
443            Self::RsaPrivateKey => b"RSA PRIVATE KEY",
444            Self::PrivateKey => b"PRIVATE KEY",
445            Self::EcPrivateKey => b"EC PRIVATE KEY",
446            Self::Crl => b"X509 CRL",
447            Self::Csr => b"CERTIFICATE REQUEST",
448            Self::EchConfigList => b"ECHCONFIG",
449        }
450    }
451}
452
453impl TryFrom<&[u8]> for SectionKind {
454    type Error = ();
455
456    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
457        Ok(match value {
458            b"CERTIFICATE" => Self::Certificate,
459            b"PUBLIC KEY" => Self::PublicKey,
460            b"RSA PRIVATE KEY" => Self::RsaPrivateKey,
461            b"PRIVATE KEY" => Self::PrivateKey,
462            b"EC PRIVATE KEY" => Self::EcPrivateKey,
463            b"X509 CRL" => Self::Crl,
464            b"CERTIFICATE REQUEST" => Self::Csr,
465            b"ECHCONFIG" => Self::EchConfigList,
466            _ => return Err(()),
467        })
468    }
469}
470
471/// Errors that may arise when parsing the contents of a PEM file
472#[non_exhaustive]
473#[derive(Debug)]
474pub enum Error {
475    /// a section is missing its "END marker" line
476    MissingSectionEnd {
477        /// the expected "END marker" line that was not found
478        end_marker: Vec<u8>,
479    },
480
481    /// syntax error found in the line that starts a new section
482    IllegalSectionStart {
483        /// line that contains the syntax error
484        line: Vec<u8>,
485    },
486
487    /// base64 decode error
488    Base64Decode(String),
489
490    /// I/O errors, from APIs that accept `std::io` types.
491    #[cfg(feature = "std")]
492    Io(io::Error),
493
494    /// No items found of desired type
495    NoItemsFound,
496}
497
498impl fmt::Display for Error {
499    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
500        match self {
501            Self::MissingSectionEnd { end_marker } => {
502                write!(f, "missing section end marker: {end_marker:?}")
503            }
504            Self::IllegalSectionStart { line } => {
505                write!(f, "illegal section start: {line:?}")
506            }
507            Self::Base64Decode(e) => write!(f, "base64 decode error: {e}"),
508            #[cfg(feature = "std")]
509            Self::Io(e) => write!(f, "I/O error: {e}"),
510            Self::NoItemsFound => write!(f, "no items found"),
511        }
512    }
513}
514
515#[cfg(feature = "std")]
516impl std::error::Error for Error {}
517
518// Ported from https://github.com/rust-lang/rust/blob/91cfcb021935853caa06698b759c293c09d1e96a/library/std/src/io/mod.rs#L1990 and
519// modified to look for our accepted newlines.
520#[cfg(feature = "std")]
521fn read_until_newline<R: io::BufRead + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> io::Result<usize> {
522    let mut read = 0;
523    loop {
524        let (done, used) = {
525            let available = match r.fill_buf() {
526                Ok(n) => n,
527                Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
528                Err(e) => return Err(e),
529            };
530            match available
531                .iter()
532                .copied()
533                .position(|b| b == b'\n' || b == b'\r')
534            {
535                Some(i) => {
536                    buf.extend_from_slice(&available[..=i]);
537                    (true, i + 1)
538                }
539                None => {
540                    buf.extend_from_slice(available);
541                    (false, available.len())
542                }
543            }
544        };
545        r.consume(used);
546        read += used;
547        if done || used == 0 {
548            return Ok(read);
549        }
550    }
551}
rustls_pki_types/pem.rs

rustls_pki_types/
pem.rs
