Implement directoryName constraint validation

Cargo.toml

@@ -92,6 +92,9 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 x509-parser = "0.18"
 
+[patch.crates-io]
+rcgen = { git = "https://github.com/sfackler/rcgen.git", branch = "explicit-dn" }
+
 [profile.bench]
 opt-level = 3
 debug = false

src/der.rs

@@ -65,9 +65,15 @@ pub(crate) enum Tag {
     OctetString = 0x04,
     OID = 0x06,
     Enum = 0x0A,
+    UTF8String = 0x0C,
     Sequence = CONSTRUCTED | 0x10, // 0x30
+    Set = CONSTRUCTED | 0x11,      // 0x31
+    PrintableString = 0x13,
+    IA5String = 0x16,
     UTCTime = 0x17,
     GeneralizedTime = 0x18,
+    UniversalString = 0x1C,
+    BMPString = 0x1E,
 
     #[expect(clippy::identity_op)]
     ContextSpecificConstructed0 = CONTEXT_SPECIFIC | CONSTRUCTED | 0,
@@ -95,6 +101,15 @@ impl From<Tag> for u8 {
     } // XXX: narrowing conversion.
 }
 
+impl Tag {
+    /// Equivalent to `u8::from(self)` but usable in `const` context, since
+    /// `From` is not const.
+    #[expect(clippy::as_conversions)]
+    pub(crate) const fn as_u8(self) -> u8 {
+        self as u8
+    }
+}
+
 #[inline(always)]
 pub(crate) fn expect_tag_and_get_value_limited<'a>(
     input: &mut untrusted::Reader<'a>,