1 files changed, 169 insertions, 0 deletions
diff --git a/src/ber/parser.rs b/src/ber/parser.rs
new file mode 100644
index 0000000..fdfdb88
--- /dev/null
+++ b/src/ber/parser.rs
@@ -0,0 +1,169 @@
+use crate::error::*;
+use crate::header::*;
+use crate::{BerParser, DerParser, FromBer, Length, Tag};
+use nom::bytes::streaming::take;
+use nom::{Err, Needed, Offset};
+use rusticata_macros::custom_check;
+
+/// Default maximum recursion limit
+pub const MAX_RECURSION: usize = 50;
+
+/// Default maximum object size (2^32)
+// pub const MAX_OBJECT_SIZE: usize = 4_294_967_295;
+
+pub trait GetObjectContent {
+    /// Return the raw content (bytes) of the next ASN.1 encoded object
+    ///
+    /// Note: if using BER and length is indefinite, terminating End-Of-Content is NOT included
+    fn get_object_content<'a>(
+        i: &'a [u8],
+        hdr: &'_ Header,
+        max_depth: usize,
+    ) -> ParseResult<'a, &'a [u8]>;
+}
+
+impl GetObjectContent for BerParser {
+    fn get_object_content<'a>(
+        i: &'a [u8],
+        hdr: &'_ Header,
+        max_depth: usize,
+    ) -> ParseResult<'a, &'a [u8]> {
+        let start_i = i;
+        let (i, _) = ber_skip_object_content(i, hdr, max_depth)?;
+        let len = start_i.offset(i);
+        let (content, i) = start_i.split_at(len);
+        // if len is indefinite, there are 2 extra bytes for EOC
+        if hdr.length == Length::Indefinite {
+            let len = content.len();
+            assert!(len >= 2);
+            Ok((i, &content[..len - 2]))
+        } else {
+            Ok((i, content))
+        }
+    }
+}
+
+impl GetObjectContent for DerParser {
+    /// Skip object content, accepting only DER
+    ///
+    /// This this function is for DER only, it cannot go into recursion (no indefinite length)
+    fn get_object_content<'a>(
+        i: &'a [u8],
+        hdr: &'_ Header,
+        _max_depth: usize,
+    ) -> ParseResult<'a, &'a [u8]> {
+        match hdr.length {
+            Length::Definite(l) => take(l)(i),
+            Length::Indefinite => Err(Err::Error(Error::DerConstraintFailed(
+                DerConstraint::IndefiniteLength,
+            ))),
+        }
+    }
+}
+
+/// Skip object content, and return true if object was End-Of-Content
+fn ber_skip_object_content<'a>(
+    i: &'a [u8],
+    hdr: &Header,
+    max_depth: usize,
+) -> ParseResult<'a, bool> {
+    if max_depth == 0 {
+        return Err(Err::Error(Error::BerMaxDepth));
+    }
+    match hdr.length {
+        Length::Definite(l) => {
+            if l == 0 && hdr.tag == Tag::EndOfContent {
+                return Ok((i, true));
+            }
+            let (i, _) = take(l)(i)?;
+            Ok((i, false))
+        }
+        Length::Indefinite => {
+            hdr.assert_constructed()?;
+            // read objects until EndOfContent (00 00)
+            // this is recursive
+            let mut i = i;
+            loop {
+                let (i2, header2) = Header::from_ber(i)?;
+                let (i3, eoc) = ber_skip_object_content(i2, &header2, max_depth - 1)?;
+                if eoc {
+                    // return false, since top object was not EndOfContent
+                    return Ok((i3, false));
+                }
+                i = i3;
+            }
+        }
+    }
+}
+
+/// Try to parse input bytes as u64
+#[inline]
+pub(crate) fn bytes_to_u64(s: &[u8]) -> core::result::Result<u64, Error> {
+    let mut u: u64 = 0;
+    for &c in s {
+        if u & 0xff00_0000_0000_0000 != 0 {
+            return Err(Error::IntegerTooLarge);
+        }
+        u <<= 8;
+        u |= u64::from(c);
+    }
+    Ok(u)
+}
+
+pub(crate) fn parse_identifier(i: &[u8]) -> ParseResult<(u8, u8, u32, &[u8])> {
+    if i.is_empty() {
+        Err(Err::Incomplete(Needed::new(1)))
+    } else {
+        let a = i[0] >> 6;
+        let b = u8::from(i[0] & 0b0010_0000 != 0);
+        let mut c = u32::from(i[0] & 0b0001_1111);
+
+        let mut tag_byte_count = 1;
+
+        if c == 0x1f {
+            c = 0;
+            loop {
+                // Make sure we don't read past the end of our data.
+                custom_check!(i, tag_byte_count >= i.len(), Error::InvalidTag)?;
+
+                // With tag defined as u32 the most we can fit in is four tag bytes.
+                // (X.690 doesn't actually specify maximum tag width.)
+                custom_check!(i, tag_byte_count > 5, Error::InvalidTag)?;
+
+                c = (c << 7) | (u32::from(i[tag_byte_count]) & 0x7f);
+                let done = i[tag_byte_count] & 0x80 == 0;
+                tag_byte_count += 1;
+                if done {
+                    break;
+                }
+            }
+        }
+
+        let (raw_tag, rem) = i.split_at(tag_byte_count);
+
+        Ok((rem, (a, b, c, raw_tag)))
+    }
+}
+
+/// Return the MSB and the rest of the first byte, or an error
+pub(crate) fn parse_ber_length_byte(i: &[u8]) -> ParseResult<(u8, u8)> {
+    if i.is_empty() {
+        Err(Err::Incomplete(Needed::new(1)))
+    } else {
+        let a = i[0] >> 7;
+        let b = i[0] & 0b0111_1111;
+        Ok((&i[1..], (a, b)))
+    }
+}
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! der_constraint_fail_if(
+    ($slice:expr, $cond:expr, $constraint:expr) => (
+        {
+            if $cond {
+                return Err(::nom::Err::Error(Error::DerConstraintFailed($constraint)));
+            }
+        }
+    );
+);