New file md-internal.h

1 files changed, 57 insertions, 0 deletions

diff --git a/md-internal.h b/md-internal.h
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+/* md-internal.h
+
+   Copyright (C) 2001, 2010, 2022 Niels Möller
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+
+#ifndef NETTLE_MD_INTERNAL_H_INCLUDED
+#define NETTLE_MD_INTERNAL_H_INCLUDED
+
+/* Internal helper macros for Merkle-Damgård hash functions. Assumes the context
+   structs includes the following fields:
+
+     uint8_t block[...];		// Buffer holding one block
+     unsigned int index;		// Index into block
+*/
+
+#define MD_FILL_OR_RETURN(ctx, length, data)			\
+  do {								\
+    unsigned __md_left = sizeof((ctx)->block) - (ctx)->index;	\
+    if ((length) < __md_left)					\
+      {								\
+	memcpy((ctx)->block + (ctx)->index, (data), (length));	\
+	(ctx)->index += (length);				\
+	return;							\
+      }								\
+    memcpy((ctx)->block + (ctx)->index, (data), __md_left);	\
+    (data) += __md_left;					\
+    (length) -= __md_left;					\
+    (ctx)->index = 0;						\
+  } while(0)
+
+#endif /* NETTLE_MD_INTERNAL_H_INCLUDED */