hcrypto: Add HMAC_CTX_new and HMAC_CTX_free

Add a pair of functions which can be used to allocate and free
an HMAC_CTX structure on the heap. This means that the caller doesn't
need to know the size of the underlying structure.

lib/hcrypto/hmac.c

@@ -66,6 +66,19 @@ HMAC_CTX_cleanup(HMAC_CTX *ctx)
     }
 }
 
+HMAC_CTX *
+HMAC_CTX_new(void)
+{
+    return calloc(1, sizeof(HMAC_CTX));
+}
+
+void
+HMAC_CTX_free(HMAC_CTX *ctx)
+{
+    HMAC_CTX_cleanup(ctx);
+    free(ctx);
+}
+
 size_t
 HMAC_size(const HMAC_CTX *ctx)
 {

lib/hcrypto/hmac.h

@@ -39,6 +39,8 @@
 #include <hcrypto/evp.h>
 
 /* symbol renaming */
+#define HMAC_CTX_new hc_HMAC_CTX_new
+#define HMAC_CTX_free hc_HMAC_CTX_free
 #define HMAC_CTX_init hc_HMAC_CTX_init
 #define HMAC_CTX_cleanup hc_HMAC_CTX_cleanup
 #define HMAC_size hc_HMAC_size
@@ -68,6 +70,8 @@ struct hc_HMAC_CTX {
 
 void	HMAC_CTX_init(HMAC_CTX *);
 void	HMAC_CTX_cleanup(HMAC_CTX *ctx);
+HMAC_CTX *HMAC_CTX_new(void);
+void    HMAC_CTX_free(HMAC_CTX *ctx);
 
 size_t	HMAC_size(const HMAC_CTX *ctx);
 

lib/hcrypto/libhcrypto-exports.def

@@ -259,6 +259,8 @@ EXPORTS
 	hc_HMAC
 	hc_HMAC_CTX_cleanup
 	hc_HMAC_CTX_init
+	hc_HMAC_CTX_free
+	hc_HMAC_CTX_new
 	hc_HMAC_Final
 	hc_HMAC_Init_ex
 	hc_HMAC_Update

lib/hcrypto/version-script.map

@@ -243,7 +243,9 @@ HEIMDAL_CRYPTO_1.0 {
 		hc_EVP_hcrypto_aes_256_cts;
 		hc_HMAC;
 		hc_HMAC_CTX_cleanup;
+		hc_HMAC_CTX_free;
 		hc_HMAC_CTX_init;
+		hc_HMAC_CTX_new;
 		hc_HMAC_Final;
 		hc_HMAC_Init_ex;
 		hc_HMAC_Update;