[MOD/WIP] Get SHA to use Open/LibreSSL if present

I still haven't tested on LibreSSL (Debian doesn't seem to actually like
it all that much), but manuals seems to state that they're the same in
that regard. If anyone is up to verify, let me know so that I'm aware
it's safe to merge it.

src/Sha/Sha1.c

@@ -28,6 +28,26 @@
 
 #include <limits.h>
 
+#if (TLS_IMPL == TLS_OPENSSL) || (TLS_IMPL == TLS_LIBRESSL)
+
+#include <openssl/sha.h>
+    
+unsigned char *
+Sha1(char *str)
+{
+    unsigned char *digest;
+    if (!str)
+    {
+        return NULL;
+    }
+
+    digest = Malloc(20 + 1);
+    SHA1((unsigned char *) str, strlen(str), digest);
+    digest[20] = '\0';
+    return digest;
+}
+#else
+
 #define LOAD32H(x, y) \
 	{ \
 		x = ((uint32_t)((y)[0] & 255) << 24) | \
@@ -264,3 +284,4 @@ Sha1(char *str)
 
     return out;
 }
+#endif

src/Sha/Sha256.c

@@ -21,14 +21,36 @@
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-#include <Sha.h>
 #include <Memory.h>
+#include <Sha.h>
 
 #include <stdio.h>
 #include <string.h>
 
 #include <limits.h>
 
+
+#if (TLS_IMPL == TLS_OPENSSL) || (TLS_IMPL == TLS_LIBRESSL)
+
+#include <openssl/sha.h>
+#include <Log.h>
+    
+unsigned char *
+Sha256(char *str)
+{
+    unsigned char *digest;
+    if (!str)
+    {
+        return NULL;
+    }
+
+    digest = Malloc(32 + 1);
+    SHA256((unsigned char *) str, strlen(str), digest);
+    digest[32] = '\0';
+    return digest;
+}
+#else
+
 #define GET_UINT32(x) \
     (((uint32_t)(x)[0] << 24) | \
      ((uint32_t)(x)[1] << 16) | \
@@ -230,3 +252,4 @@ Sha256(char *str)
 
     return out;
 }
+#endif