1 files changed, 60 insertions, 0 deletions
diff --git a/vendor/der/src/header.rs b/vendor/der/src/header.rs
new file mode 100644
index 0000000..ad30381
--- /dev/null
+++ b/vendor/der/src/header.rs
@@ -0,0 +1,60 @@
+//! ASN.1 DER headers.
+
+use crate::{Decode, DerOrd, Encode, ErrorKind, Length, Reader, Result, Tag, Writer};
+use core::cmp::Ordering;
+
+/// ASN.1 DER headers: tag + length component of TLV-encoded values
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub struct Header {
+    /// Tag representing the type of the encoded value
+    pub tag: Tag,
+
+    /// Length of the encoded value
+    pub length: Length,
+}
+
+impl Header {
+    /// Create a new [`Header`] from a [`Tag`] and a specified length.
+    ///
+    /// Returns an error if the length exceeds the limits of [`Length`].
+    pub fn new(tag: Tag, length: impl TryInto<Length>) -> Result<Self> {
+        let length = length.try_into().map_err(|_| ErrorKind::Overflow)?;
+        Ok(Self { tag, length })
+    }
+}
+
+impl<'a> Decode<'a> for Header {
+    fn decode<R: Reader<'a>>(reader: &mut R) -> Result<Header> {
+        let tag = Tag::decode(reader)?;
+
+        let length = Length::decode(reader).map_err(|e| {
+            if e.kind() == ErrorKind::Overlength {
+                ErrorKind::Length { tag }.into()
+            } else {
+                e
+            }
+        })?;
+
+        Ok(Self { tag, length })
+    }
+}
+
+impl Encode for Header {
+    fn encoded_len(&self) -> Result<Length> {
+        self.tag.encoded_len()? + self.length.encoded_len()?
+    }
+
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
+        self.tag.encode(writer)?;
+        self.length.encode(writer)
+    }
+}
+
+impl DerOrd for Header {
+    fn der_cmp(&self, other: &Self) -> Result<Ordering> {
+        match self.tag.der_cmp(&other.tag)? {
+            Ordering::Equal => self.length.der_cmp(&other.length),
+            ordering => Ok(ordering),
+        }
+    }
+}