Add a stateful SHA256 hasher

openssl-sys/src/lib.rs

@@ -128,6 +128,16 @@ pub struct X509V3_CTX {
     // Maybe more here
 }
 
+#[repr(C)]
+pub struct SHA256_CTX {
+    pub h: [SHA_LONG; 8],
+    pub Nl: SHA_LONG,
+    pub Nh: SHA_LONG,
+    pub data: [SHA_LONG; SHA_LBLOCK as usize],
+    pub num: c_uint,
+    pub md_len: c_uint,
+}
+
 #[cfg(target_pointer_width = "64")]
 pub type BN_ULONG = libc::c_ulonglong;
 #[cfg(target_pointer_width = "32")]
@@ -159,6 +169,8 @@ pub type PasswordCallback = unsafe extern "C" fn(buf: *mut c_char,
                                                  user_data: *mut c_void)
                                                  -> c_int;
 
+pub type SHA_LONG = c_uint;
+
 pub const AES_ENCRYPT: c_int = 1;
 pub const AES_DECRYPT: c_int = 0;
 
@@ -1169,6 +1181,8 @@ pub const RSA_NO_PADDING: c_int = 3;
 pub const RSA_PKCS1_OAEP_PADDING: c_int = 4;
 pub const RSA_X931_PADDING: c_int = 5;
 
+pub const SHA_LBLOCK: c_int = 16;
+
 pub const SSL_CTRL_SET_TMP_DH: c_int = 3;
 pub const SSL_CTRL_SET_TMP_ECDH: c_int = 4;
 pub const SSL_CTRL_EXTRA_CHAIN_CERT: c_int = 14;
@@ -2221,6 +2235,10 @@ extern "C" {
     pub fn SHA384(d: *const c_uchar, n: size_t, md: *mut c_uchar) -> *mut c_uchar;
     pub fn SHA512(d: *const c_uchar, n: size_t, md: *mut c_uchar) -> *mut c_uchar;
 
+    pub fn SHA256_Init(c: *mut SHA256_CTX) -> c_int;
+    pub fn SHA256_Update(c: *mut SHA256_CTX, data: *const c_void, len: size_t) -> c_int;
+    pub fn SHA256_Final(md: *mut c_uchar, c: *mut SHA256_CTX) -> c_int;
+
     pub fn SSL_new(ctx: *mut SSL_CTX) -> *mut SSL;
     pub fn SSL_pending(ssl: *const SSL) -> c_int;
     pub fn SSL_free(ssl: *mut SSL);

openssl/src/sha.rs

@@ -1,4 +1,5 @@
 //! The SHA family of hashes.
+use libc::c_void;
 use ffi;
 use std::mem;
 
@@ -57,6 +58,41 @@ pub fn sha512(data: &[u8]) -> [u8; 64] {
     }
 }
 
+/// An object which calculates a SHA256 hash of some data.
+pub struct Sha256(ffi::SHA256_CTX);
+
+impl Sha256 {
+    /// Creates a new hasher.
+    #[inline]
+    pub fn new() -> Sha256 {
+        unsafe {
+            let mut ctx = mem::uninitialized();
+            ffi::SHA256_Init(&mut ctx);
+            Sha256(ctx)
+        }
+    }
+
+    /// Feeds some data into the hasher.
+    ///
+    /// This can be called multiple times.
+    #[inline]
+    pub fn update(&mut self, buf: &[u8]) {
+        unsafe {
+            ffi::SHA256_Update(&mut self.0, buf.as_ptr() as *const c_void, buf.len());
+        }
+    }
+
+    /// Returns the hash of the data.
+    #[inline]
+    pub fn finish(mut self) -> [u8; 32] {
+        unsafe {
+            let mut hash: [u8; 32] = mem::uninitialized();
+            ffi::SHA256_Final(hash.as_mut_ptr(), &mut self.0);
+            hash
+        }
+    }
+}
+
 #[cfg(test)]
 mod test {
     use hex::ToHex;
@@ -87,6 +123,16 @@ mod test {
         assert_eq!(sha256(data).to_hex(), expected);
     }
 
+    #[test]
+    fn struct_256() {
+        let expected = "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad";
+
+        let mut hasher = Sha256::new();
+        hasher.update(b"a");
+        hasher.update(b"bc");
+        assert_eq!(hasher.finish().to_hex(), expected);
+    }
+
     #[test]
     fn standalone_384() {
         let data = b"abc";