cipher: allow cipher name in GetCipherPtr()

The function GetCipherPtr() is used when we want a const EVP_CIPHER that
represents a cipher algorithm. This change allows users to write a code
that exports a PKey encrypted without creating an OpenSSL::Cipher
instance:

  pkey = OpenSSL::PKey.read(...)
  pkey.export("aes-128-cbc") { password }

This is the same as what happened to GetDigestPtr() in r12128.

1 files changed, 16 insertions, 3 deletions

diff --git a/ext/openssl/ossl_cipher.c b/ext/openssl/ossl_cipher.c
index 66d65e3f..c23105ab 100644
--- a/ext/openssl/ossl_cipher.c
+++ b/ext/openssl/ossl_cipher.c
@@ -54,11 +54,24 @@ static const rb_data_type_t ossl_cipher_type = {
 const EVP_CIPHER *
 GetCipherPtr(VALUE obj)
 {
-    EVP_CIPHER_CTX *ctx;
+    if (rb_obj_is_kind_of(obj, cCipher)) {
+	EVP_CIPHER_CTX *ctx;
+
+	GetCipher(obj, ctx);
+
+	return EVP_CIPHER_CTX_cipher(ctx);
+    }
+    else {
+	const EVP_CIPHER *cipher;
 
-    SafeGetCipher(obj, ctx);
+	StringValueCStr(obj);
+	cipher = EVP_get_cipherbyname(RSTRING_PTR(obj));
+	if (!cipher)
+	    ossl_raise(rb_eArgError,
+		       "unsupported cipher algorithm: %"PRIsVALUE, obj);
 
-    return EVP_CIPHER_CTX_cipher(ctx);
+	return cipher;
+    }
 }
 
 VALUE