allow conversion from MessageDigest to Md

openssl/src/md.rs

@@ -8,19 +8,18 @@ use crate::error::ErrorStack;
 use crate::lib_ctx::LibCtxRef;
 use crate::nid::Nid;
 use cfg_if::cfg_if;
+use foreign_types::ForeignType;
 use foreign_types::{ForeignTypeRef, Opaque};
 use openssl_macros::corresponds;
 #[cfg(ossl300)]
 use std::ffi::CString;
+use std::ops::Deref;
 #[cfg(ossl300)]
 use std::ptr;
 
 cfg_if! {
     if #[cfg(ossl300)] {
-        use foreign_types::ForeignType;
-        use std::ops::{Deref, DerefMut};
-
-        type Inner = *mut ffi::EVP_MD;
+        use std::ops::DerefMut;
 
         impl Drop for Md {
             #[inline]
@@ -31,32 +30,6 @@ cfg_if! {
             }
         }
 
-        impl ForeignType for Md {
-            type CType = ffi::EVP_MD;
-            type Ref = MdRef;
-
-            #[inline]
-            unsafe fn from_ptr(ptr: *mut Self::CType) -> Self {
-                Md(ptr)
-            }
-
-            #[inline]
-            fn as_ptr(&self) -> *mut Self::CType {
-                self.0
-            }
-        }
-
-        impl Deref for Md {
-            type Target = MdRef;
-
-            #[inline]
-            fn deref(&self) -> &Self::Target {
-                unsafe {
-                    MdRef::from_ptr(self.as_ptr())
-                }
-            }
-        }
-
         impl DerefMut for Md {
             #[inline]
             fn deref_mut(&mut self) -> &mut Self::Target {
@@ -65,17 +38,45 @@ cfg_if! {
                 }
             }
         }
-    } else {
-        enum Inner {}
+    }
+}
+
+impl ForeignType for Md {
+    type CType = ffi::EVP_MD;
+    type Ref = MdRef;
+
+    #[inline]
+    unsafe fn from_ptr(ptr: *mut Self::CType) -> Self {
+        Md(ptr)
+    }
+
+    #[inline]
+    fn as_ptr(&self) -> *mut Self::CType {
+        self.0
+    }
+}
+
+impl Deref for Md {
+    type Target = MdRef;
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        unsafe { MdRef::from_ptr(self.as_ptr()) }
     }
 }
 
 /// A message digest algorithm.
-pub struct Md(Inner);
+pub struct Md(*mut ffi::EVP_MD);
 
 unsafe impl Sync for Md {}
 unsafe impl Send for Md {}
 
+impl From<crate::hash::MessageDigest> for Md {
+    fn from(value: crate::hash::MessageDigest) -> Self {
+        unsafe { Md::from_ptr(value.as_ptr() as *mut _) }
+    }
+}
+
 impl Md {
     /// Returns the `Md` corresponding to an [`Nid`].
     #[corresponds(EVP_get_digestbynid)]

openssl/src/md_ctx.rs

@@ -549,4 +549,22 @@ mod test {
         // Validate result of digest of "World"
         assert_eq!(reset_result, world_expected);
     }
+
+    #[test]
+    fn from_message_digest() {
+        let messagedigest = crate::hash::MessageDigest::from_name("sha256").unwrap();
+        let md = Md::from(messagedigest);
+        let mut ctx = MdCtx::new().unwrap();
+        ctx.digest_init(&md).unwrap();
+        ctx.digest_update(b"test").unwrap();
+        let mut digest = [0; 32];
+        ctx.digest_final(digest.as_mut_slice()).unwrap();
+        // It is safe to call EVP_MD_free on const EVP_MDs from MessageDigest, but
+        // let's test it anyway before we use the original const EVP_MD in a hasher
+        drop(md);
+        let mut h = crate::hash::Hasher::new(messagedigest).unwrap();
+        h.update(b"test").unwrap();
+        let output = h.finish().unwrap();
+        assert_eq!(digest, *output);
+    }
 }