der: remove lifetime from OctetStringRef

Following the pattern of #1921, removes the lifetime from the struct,
instead changing `OctetStringRef` to a proper reference type to be used
as `&OctetStringRef`.

This makes it possible to `impl Borrow<OctetStringRef> for OctetString`
and `impl ToOwned for OctetStringRef`, so they can work with `Cow`.

Author: tarcieri

cms/src/attr.rs

@@ -1,11 +1,11 @@
 //! Attribute-related types
+//!
 use alloc::{boxed::Box, vec};
+use core::borrow::Borrow;
 use der::{
     DecodeValue, EncodeValue, FixedTag, Length, Tag,
     asn1::{OctetString, OctetStringRef},
-    referenced::OwnedToRef,
 };
-
 use x509_cert::time::Time;
 
 use crate::signed_data::SignerInfo;
@@ -50,8 +50,8 @@ impl MessageDigest {
 
     /// Return an [`OctetStringRef`] pointing to the underlying data
     #[inline]
-    pub fn as_octet_string_ref<'a>(&'a self) -> OctetStringRef<'a> {
-        self.0.owned_to_ref()
+    pub fn as_octet_string_ref(&self) -> &OctetStringRef {
+        self.0.borrow()
     }
 }
 

cms/src/timestamped_data.rs

@@ -44,7 +44,7 @@ pub struct TimeStampedData<'a> {
     #[asn1(optional = "true")]
     pub meta_data: Option<MetaData>,
     #[asn1(optional = "true")]
-    pub content: Option<OctetStringRef<'a>>,
+    pub content: Option<&'a OctetStringRef>,
     pub temporal_evidence: Evidence,
 }
 

cms/tests/builder.rs

@@ -946,7 +946,7 @@ fn test_create_password_recipient_info() {
             .to_der()
             .unwrap();
         let iv = Iv::<cbc::Decryptor<Aes128>>::try_from(
-            OctetStringRef::from_der(algorithm_params_der.as_slice())
+            <&OctetStringRef>::from_der(algorithm_params_der.as_slice())
                 .unwrap()
                 .as_bytes(),
         )

cms/tests/tests_from_pkcs7_crate.rs

@@ -123,7 +123,7 @@ fn cms_decode_signed_der() {
         sd.encap_content_info
             .econtent
             .unwrap()
-            .decode_as::<OctetStringRef>()
+            .decode_as::<&OctetStringRef>()
             .unwrap()
             .as_bytes()
             .len(),

der/src/asn1.rs

@@ -44,7 +44,7 @@ pub use self::{
     ia5_string::Ia5StringRef,
     integer::{int::IntRef, uint::UintRef},
     null::Null,
-    octet_string::OctetStringRef,
+    octet_string::{OctetStringRef, OctetStringRef2},
     printable_string::PrintableStringRef,
     private::{Private, PrivateRef},
     sequence::{Sequence, SequenceRef},