145 lines
4.1 KiB
C
145 lines
4.1 KiB
C
/* sha256.c - Functions to compute SHA256 and SHA224 message digest of files or
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memory blocks according to the NIST specification FIPS-180-2.
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Copyright (C) 2005-2006, 2008-2023 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by David Madore, considerably copypasting from
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Scott G. Miller's sha1.c
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*/
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#include <config.h>
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/* Specification. */
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#if HAVE_OPENSSL_SHA256
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# define GL_OPENSSL_INLINE _GL_EXTERN_INLINE
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#endif
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#include "sha256.h"
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#include <stdlib.h>
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#if USE_UNLOCKED_IO
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# include "unlocked-io.h"
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#endif
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#include "af_alg.h"
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#define BLOCKSIZE 32768
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#if BLOCKSIZE % 64 != 0
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# error "invalid BLOCKSIZE"
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#endif
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/* Compute message digest for bytes read from STREAM using algorithm ALG.
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Write the message digest into RESBLOCK, which contains HASHLEN bytes.
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The initial and finishing operations are INIT_CTX and FINISH_CTX.
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Return zero if and only if successful. */
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static int
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shaxxx_stream (FILE *stream, char const *alg, void *resblock,
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ssize_t hashlen, void (*init_ctx) (struct sha256_ctx *),
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void *(*finish_ctx) (struct sha256_ctx *, void *))
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{
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switch (afalg_stream (stream, alg, resblock, hashlen))
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{
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case 0: return 0;
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case -EIO: return 1;
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}
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char *buffer = malloc (BLOCKSIZE + 72);
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if (!buffer)
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return 1;
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struct sha256_ctx ctx;
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init_ctx (&ctx);
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size_t sum;
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/* Iterate over full file contents. */
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while (1)
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{
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/* We read the file in blocks of BLOCKSIZE bytes. One call of the
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computation function processes the whole buffer so that with the
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next round of the loop another block can be read. */
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size_t n;
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sum = 0;
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/* Read block. Take care for partial reads. */
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while (1)
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{
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/* Either process a partial fread() from this loop,
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or the fread() in afalg_stream may have gotten EOF.
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We need to avoid a subsequent fread() as EOF may
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not be sticky. For details of such systems, see:
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https://sourceware.org/bugzilla/show_bug.cgi?id=1190 */
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if (feof (stream))
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goto process_partial_block;
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n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
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sum += n;
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if (sum == BLOCKSIZE)
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break;
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if (n == 0)
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{
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/* Check for the error flag IFF N == 0, so that we don't
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exit the loop after a partial read due to e.g., EAGAIN
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or EWOULDBLOCK. */
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if (ferror (stream))
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{
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free (buffer);
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return 1;
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}
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goto process_partial_block;
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}
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}
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/* Process buffer with BLOCKSIZE bytes. Note that
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BLOCKSIZE % 64 == 0
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*/
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sha256_process_block (buffer, BLOCKSIZE, &ctx);
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}
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process_partial_block:;
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/* Process any remaining bytes. */
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if (sum > 0)
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sha256_process_bytes (buffer, sum, &ctx);
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/* Construct result in desired memory. */
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finish_ctx (&ctx, resblock);
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free (buffer);
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return 0;
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}
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int
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sha256_stream (FILE *stream, void *resblock)
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{
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return shaxxx_stream (stream, "sha256", resblock, SHA256_DIGEST_SIZE,
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sha256_init_ctx, sha256_finish_ctx);
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}
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int
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sha224_stream (FILE *stream, void *resblock)
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{
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return shaxxx_stream (stream, "sha224", resblock, SHA224_DIGEST_SIZE,
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sha224_init_ctx, sha224_finish_ctx);
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}
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/*
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* Hey Emacs!
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* Local Variables:
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* coding: utf-8
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* End:
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*/
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