Fix raw key wrappers: len can't be discarded

Author: dagood

ed25519.go

@@ -145,12 +145,12 @@ func NewPrivateKeyEd25519FromSeed(seed []byte) (*PrivateKeyEd25519, error) {
 }
 
 func extractPKEYPubEd25519(pkey C.GO_EVP_PKEY_PTR, pub []byte) error {
-	pubSize := C.size_t(publicKeySizeEd25519)
-	if C.go_openssl_EVP_PKEY_get_raw_public_key_wrapper(pkey, base(pub), pubSize) != 1 {
+	r := C.go_openssl_EVP_PKEY_get_raw_public_key_wrapper(pkey, base(pub), C.size_t(publicKeySizeEd25519))
+	if r.result != 1 {
 		return newOpenSSLError("EVP_PKEY_get_raw_public_key")
 	}
-	if pubSize != publicKeySizeEd25519 {
-		return errors.New("ed25519: bad public key length: " + strconv.Itoa(int(pubSize)))
+	if r.len != publicKeySizeEd25519 {
+		return errors.New("ed25519: bad public key length: " + strconv.Itoa(int(r.len)))
 	}
 	return nil
 }
@@ -159,12 +159,12 @@ func extractPKEYPrivEd25519(pkey C.GO_EVP_PKEY_PTR, priv []byte) error {
 	if err := extractPKEYPubEd25519(pkey, priv[seedSizeEd25519:]); err != nil {
 		return err
 	}
-	privSize := C.size_t(seedSizeEd25519)
-	if C.go_openssl_EVP_PKEY_get_raw_private_key_wrapper(pkey, base(priv), privSize) != 1 {
+	r := C.go_openssl_EVP_PKEY_get_raw_private_key_wrapper(pkey, base(priv), C.size_t(seedSizeEd25519))
+	if r.result != 1 {
 		return newOpenSSLError("EVP_PKEY_get_raw_private_key")
 	}
-	if privSize != seedSizeEd25519 {
-		return errors.New("ed25519: bad private key length: " + strconv.Itoa(int(privSize)))
+	if r.len != seedSizeEd25519 {
+		return errors.New("ed25519: bad private key length: " + strconv.Itoa(int(r.len)))
 	}
 	return nil
 }

goopenssl.h

@@ -82,9 +82,8 @@ go_hash_sum(GO_EVP_MD_CTX_PTR ctx, GO_EVP_MD_CTX_PTR ctx2, unsigned char *out)
     return go_openssl_EVP_DigestFinal(ctx2, out, NULL);
 }
 
-// These wrappers allocate length variables on the C stack to avoid having to pass a pointer from Go, which would escape to the heap.
+// These wrappers allocate out_len on the C stack to avoid having to pass a pointer from Go, which would escape to the heap.
 // Use them only in situations where the output length can be safely discarded.
-
 static inline int
 go_openssl_EVP_EncryptUpdate_wrapper(GO_EVP_CIPHER_CTX_PTR ctx, unsigned char *out, const unsigned char *in, int in_len)
 {
@@ -106,18 +105,6 @@ go_openssl_EVP_CipherUpdate_wrapper(GO_EVP_CIPHER_CTX_PTR ctx, unsigned char *ou
     return go_openssl_EVP_CipherUpdate(ctx, out, &len, in, in_len);
 }
 
-static inline int
-go_openssl_EVP_PKEY_get_raw_public_key_wrapper(const GO_EVP_PKEY_PTR pkey, unsigned char *pub, size_t len)
-{
-    return go_openssl_EVP_PKEY_get_raw_public_key(pkey, pub, &len);
-}
-
-static inline int
-go_openssl_EVP_PKEY_get_raw_private_key_wrapper(const GO_EVP_PKEY_PTR pkey, unsigned char *priv, size_t len)
-{
-    return go_openssl_EVP_PKEY_get_raw_private_key(pkey, priv, &len);
-}
-
 // These wrappers also allocate length variables on the C stack to avoid escape to the heap, but do return the result.
 // A struct is returned that contains multiple return values instead of OpenSSL's approach of using pointers.
 
@@ -135,6 +122,28 @@ go_openssl_EVP_PKEY_derive_wrapper(GO_EVP_PKEY_CTX_PTR ctx, unsigned char *key,
     return r;
 }
 
+typedef struct
+{
+    int result;
+    size_t len;
+} go_openssl_EVP_PKEY_get_raw_key_out;
+
+static inline go_openssl_EVP_PKEY_get_raw_key_out
+go_openssl_EVP_PKEY_get_raw_public_key_wrapper(const GO_EVP_PKEY_PTR pkey, unsigned char *pub, size_t len)
+{
+    go_openssl_EVP_PKEY_get_raw_key_out r = {0, len};
+    r.result = go_openssl_EVP_PKEY_get_raw_public_key(pkey, pub, &r.len);
+    return r;
+}
+
+static inline go_openssl_EVP_PKEY_get_raw_key_out
+go_openssl_EVP_PKEY_get_raw_private_key_wrapper(const GO_EVP_PKEY_PTR pkey, unsigned char *priv, size_t len)
+{
+    go_openssl_EVP_PKEY_get_raw_key_out r = {0, len};
+    r.result = go_openssl_EVP_PKEY_get_raw_private_key(pkey, priv, &r.len);
+    return r;
+}
+
 typedef struct
 {
     int result;