der: clarify writer: add pretty-printing DER hex with comments

.github/workflows/der.yml

@@ -37,7 +37,7 @@ jobs:
           toolchain: ${{ matrix.rust }}
           targets: ${{ matrix.target }}
       - uses: RustCrypto/actions/cargo-hack-install@master
-      - run: cargo hack build --target ${{ matrix.target }} --feature-powerset --exclude-features arbitrary,std
+      - run: cargo hack build --target ${{ matrix.target }} --feature-powerset --exclude-features arbitrary,std,clarify
 
   minimal-versions:
     if: false # TODO: temp disabled due to unpublished prerelease dependencies

der/Cargo.toml

@@ -26,12 +26,14 @@ pem-rfc7468 = { version = "1.0.0-rc.3", optional = true, features = ["alloc"] }
 time = { version = "0.3.4", optional = true, default-features = false }
 zeroize = { version = "1.8", optional = true, default-features = false }
 heapless = { version = "0.8", optional = true, default-features = false }
+tynm = { version = "0.2", optional = true, default-features = false }
 
 [dev-dependencies]
 hex-literal = "1"
 proptest = "1"
 
 [features]
+default = []
 alloc = ["zeroize?/alloc"]
 std = ["alloc"]
 
@@ -41,6 +43,7 @@ derive = ["dep:der_derive"]
 oid = ["dep:const-oid"]
 pem = ["dep:pem-rfc7468", "alloc", "zeroize"]
 real = []
+clarify = ["std", "pem", "dep:tynm", "derive", "oid"]
 
 [package.metadata.docs.rs]
 all-features = true

der/src/asn1/any.rs

@@ -87,6 +87,7 @@ impl<'a> AnyRef<'a> {
 
         let mut decoder = SliceReader::new_with_encoding_rules(self.value(), encoding)?;
         let result = T::decode_value(&mut decoder, self.header())?;
+
         decoder.finish()?;
         Ok(result)
     }

der/src/encode.rs

@@ -81,7 +81,26 @@ where
     /// Encode this value as ASN.1 DER using the provided [`Writer`].
     fn encode(&self, writer: &mut impl Writer) -> Result<()> {
         self.header()?.encode(writer)?;
-        self.encode_value(writer)
+        clarify_start_value_type::<T>(writer);
+        let result = self.encode_value(writer);
+        clarify_end_value_type::<T>(writer);
+        result
+    }
+}
+
+#[allow(unused_variables)]
+fn clarify_start_value_type<T: ?Sized>(writer: &mut impl Writer) {
+    #[cfg(feature = "clarify")]
+    if let Some(clarifier) = writer.clarifier() {
+        clarifier.clarify_start_value_type::<T>();
+    }
+}
+
+#[allow(unused_variables)]
+fn clarify_end_value_type<T: ?Sized>(writer: &mut impl Writer) {
+    #[cfg(feature = "clarify")]
+    if let Some(clarifier) = writer.clarifier() {
+        clarifier.clarify_end_value_type::<T>();
     }
 }
 

der/src/header.rs

@@ -61,8 +61,27 @@ impl Encode for Header {
     }
 
     fn encode(&self, writer: &mut impl Writer) -> Result<()> {
+        clarify_start_tag(writer, &self.tag);
         self.tag.encode(writer)?;
-        self.length.encode(writer)
+        let result = self.length.encode(writer);
+        clarify_end_length(writer, &self.tag, self.length);
+        result
+    }
+}
+
+#[allow(unused_variables)]
+fn clarify_start_tag(writer: &mut impl Writer, tag: &Tag) {
+    #[cfg(feature = "clarify")]
+    if let Some(clarifier) = writer.clarifier() {
+        clarifier.clarify_header_start_tag(tag);
+    }
+}
+
+#[allow(unused_variables)]
+fn clarify_end_length(writer: &mut impl Writer, tag: &Tag, length: Length) {
+    #[cfg(feature = "clarify")]
+    if let Some(clarifier) = writer.clarifier() {
+        clarifier.clarify_header_end_length(Some(tag), length);
     }
 }
 

der/src/lib.rs

@@ -395,6 +395,11 @@ pub use {
     pem_rfc7468 as pem,
 };
 
+#[cfg(feature = "clarify")]
+pub use writer::clarify::{
+    Clarifier, ClarifyFlavor, ClarifyOptions, ClarifySliceWriter, EncodeClarifyExt,
+};
+
 #[cfg(feature = "time")]
 pub use time;
 

der/src/writer.rs

@@ -1,5 +1,7 @@
 //! Writer trait.
 
+#[cfg(feature = "clarify")]
+pub mod clarify;
 #[cfg(feature = "pem")]
 pub(crate) mod pem;
 pub(crate) mod slice;
@@ -18,6 +20,12 @@ pub trait Writer {
     fn write_byte(&mut self, byte: u8) -> Result<()> {
         self.write(&[byte])
     }
+
+    #[cfg(feature = "clarify")]
+    /// Should return Some(clarifier) for clarify writers
+    fn clarifier(&mut self) -> Option<&mut clarify::Clarifier> {
+        None
+    }
 }
 
 #[cfg(feature = "std")]