der: fix derive optional OCTET/BIT STRING on Option<&[u8]>

der/tests/derive.rs

@@ -441,8 +441,19 @@ mod sequence {
         pub typed: &'a [u8],
         #[asn1(context_specific = "0")]
         pub context_specific: bool,
+
         #[asn1(optional = "true")]
         pub optional: Option<bool>,
+
+        #[asn1(type = "OCTET STRING", optional = "true")]
+        pub optional_octet_string: Option<&'a [u8]>,
+
+        #[asn1(type = "BIT STRING", optional = "true")]
+        pub optional_bit_string: Option<&'a [u8]>,
+
+        #[asn1(optional = "true")]
+        pub optional_oid: Option<ObjectIdentifier>,
+
         #[asn1(default = "default_false_example")]
         pub default: bool,
         #[asn1(type = "BIT STRING", context_specific = "1")]
@@ -467,6 +478,9 @@ mod sequence {
     #[test]
     fn type_combinations_instance() {
         let obj = TypeCheckExpandedSequenceFieldAttributeCombinations {
+            optional: Some(true),
+            optional_octet_string: Some(&[0xAA, 0xBB]),
+            optional_bit_string: Some(&[0xCC, 0xDD]),
             context_specific_optional: Some(true),
             typed_context_specific: &[0, 1],
             typed_context_specific_optional_bits: Some(&[2, 3]),
@@ -477,6 +491,7 @@ mod sequence {
         };
 
         let der_encoded = obj.to_der().unwrap();
+
         let obj_decoded =
             TypeCheckExpandedSequenceFieldAttributeCombinations::from_der(&der_encoded).unwrap();
         assert_eq!(obj, obj_decoded);

der_derive/src/asn1_type.rs

@@ -54,17 +54,13 @@ impl Asn1Type {
 
     /// Get a `der::Decoder` object for a particular ASN.1 type
     pub fn decoder(self) -> TokenStream {
-        match self {
-            Asn1Type::BitString => quote!(::der::asn1::BitStringRef::decode(reader)?),
-            Asn1Type::Ia5String => quote!(::der::asn1::Ia5StringRef::decode(reader)?),
-            Asn1Type::GeneralizedTime => quote!(::der::asn1::GeneralizedTime::decode(reader)?),
-            Asn1Type::OctetString => quote!(::der::asn1::OctetStringRef::decode(reader)?),
-            Asn1Type::PrintableString => quote!(::der::asn1::PrintableStringRef::decode(reader)?),
-            Asn1Type::TeletexString => quote!(::der::asn1::TeletexStringRef::decode(reader)?),
-            Asn1Type::VideotexString => quote!(::der::asn1::VideotexStringRef::decode(reader)?),
-            Asn1Type::UtcTime => quote!(::der::asn1::UtcTime::decode(reader)?),
-            Asn1Type::Utf8String => quote!(::der::asn1::Utf8StringRef::decode(reader)?),
-        }
+        let type_path = self.type_path();
+        quote!(#type_path::decode(reader)?)
+    }
+    /// Get a `der::Decoder` optional object for a particular ASN.1 type
+    pub fn decoder_optional(self) -> TokenStream {
+        let type_path = self.type_path();
+        quote!(Option::<#type_path>::decode(reader)?)
     }
 
     /// Get a `der::Encoder` object for a particular ASN.1 type

der_derive/src/attributes.rs

@@ -299,6 +299,10 @@ impl FieldAttrs {
                     Option::<#type_params>::decode(reader)?.unwrap_or_else(#default),
                 }
             })
+        } else if self.is_optional() {
+            self.asn1_type
+                .map(|ty| ty.decoder_optional())
+                .unwrap_or_else(|| quote!(reader.decode()?))
         } else {
             self.asn1_type
                 .map(|ty| ty.decoder())