Add EVP_PKEY_get0_* functions.

Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
diff --git a/crypto/evp/p_lib.c b/crypto/evp/p_lib.c
index 01f8a72..7d255af 100644
--- a/crypto/evp/p_lib.c
+++ b/crypto/evp/p_lib.c
@@ -204,6 +204,11 @@
     return (ret);
 }
 
+void EVP_PKEY_up_ref(EVP_PKEY *pkey)
+{
+    CRYPTO_add(&pkey->references, 1, CRYPTO_LOCK_EVP_PKEY);
+}
+
 /*
  * Setup a public key ASN1 method and ENGINE from a NID or a string. If pkey
  * is NULL just return 1 or 0 if the algorithm exists.
@@ -284,15 +289,22 @@
     return ret;
 }
 
-RSA *EVP_PKEY_get1_RSA(EVP_PKEY *pkey)
+RSA *EVP_PKEY_get0_RSA(EVP_PKEY *pkey)
 {
     if (pkey->type != EVP_PKEY_RSA) {
-        EVPerr(EVP_F_EVP_PKEY_GET1_RSA, EVP_R_EXPECTING_AN_RSA_KEY);
+        EVPerr(EVP_F_EVP_PKEY_GET0_RSA, EVP_R_EXPECTING_AN_RSA_KEY);
         return NULL;
     }
-    RSA_up_ref(pkey->pkey.rsa);
     return pkey->pkey.rsa;
 }
+
+RSA *EVP_PKEY_get1_RSA(EVP_PKEY *pkey)
+{
+    RSA *ret = EVP_PKEY_get0_RSA(pkey);
+    if (ret != NULL)
+        RSA_up_ref(ret);
+    return ret;
+}
 #endif
 
 #ifndef OPENSSL_NO_DSA
@@ -304,15 +316,22 @@
     return ret;
 }
 
-DSA *EVP_PKEY_get1_DSA(EVP_PKEY *pkey)
+DSA *EVP_PKEY_get0_DSA(EVP_PKEY *pkey)
 {
     if (pkey->type != EVP_PKEY_DSA) {
-        EVPerr(EVP_F_EVP_PKEY_GET1_DSA, EVP_R_EXPECTING_A_DSA_KEY);
+        EVPerr(EVP_F_EVP_PKEY_GET0_DSA, EVP_R_EXPECTING_A_DSA_KEY);
         return NULL;
     }
-    DSA_up_ref(pkey->pkey.dsa);
     return pkey->pkey.dsa;
 }
+
+DSA *EVP_PKEY_get1_DSA(EVP_PKEY *pkey)
+{
+    DSA *ret = EVP_PKEY_get0_DSA(pkey);
+    if (ret != NULL)
+        DSA_up_ref(ret);
+    return ret;
+}
 #endif
 
 #ifndef OPENSSL_NO_EC
@@ -325,15 +344,22 @@
     return ret;
 }
 
-EC_KEY *EVP_PKEY_get1_EC_KEY(EVP_PKEY *pkey)
+EC_KEY *EVP_PKEY_get0_EC_KEY(EVP_PKEY *pkey)
 {
     if (pkey->type != EVP_PKEY_EC) {
-        EVPerr(EVP_F_EVP_PKEY_GET1_EC_KEY, EVP_R_EXPECTING_A_EC_KEY);
+        EVPerr(EVP_F_EVP_PKEY_GET0_EC_KEY, EVP_R_EXPECTING_A_EC_KEY);
         return NULL;
     }
-    EC_KEY_up_ref(pkey->pkey.ec);
     return pkey->pkey.ec;
 }
+
+EC_KEY *EVP_PKEY_get1_EC_KEY(EVP_PKEY *pkey)
+{
+    EC_KEY *ret = EVP_PKEY_get0_EC_KEY(pkey);
+    if (ret != NULL)
+        EC_KEY_up_ref(ret);
+    return ret;
+}
 #endif
 
 #ifndef OPENSSL_NO_DH
@@ -346,15 +372,22 @@
     return ret;
 }
 
-DH *EVP_PKEY_get1_DH(EVP_PKEY *pkey)
+DH *EVP_PKEY_get0_DH(EVP_PKEY *pkey)
 {
     if (pkey->type != EVP_PKEY_DH && pkey->type != EVP_PKEY_DHX) {
-        EVPerr(EVP_F_EVP_PKEY_GET1_DH, EVP_R_EXPECTING_A_DH_KEY);
+        EVPerr(EVP_F_EVP_PKEY_GET0_DH, EVP_R_EXPECTING_A_DH_KEY);
         return NULL;
     }
-    DH_up_ref(pkey->pkey.dh);
     return pkey->pkey.dh;
 }
+
+DH *EVP_PKEY_get1_DH(EVP_PKEY *pkey)
+{
+    DH *ret = EVP_PKEY_get0_DH(pkey);
+    if (ret != NULL)
+        DH_up_ref(ret);
+    return ret;
+}
 #endif
 
 int EVP_PKEY_type(int type)