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/* Functions to compute MD5 message digest of files or memory blocks.
according to the definition of MD5 in RFC 1321 from April 1992.
Copyright (C) 1995-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995. */
#include <string.h>
#include <endian.h>
#include "md5.h"
#if __BYTE_ORDER == __BIG_ENDIAN
# define WORDS_BIGENDIAN 1
#endif
#ifdef WORDS_BIGENDIAN
# define SWAP(n) \
(((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
#else
# define SWAP(n) (n)
#endif
/* This array contains the bytes used to pad the buffer to the next
64-byte boundary. (RFC 1321, 3.1: Step 1) */
static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
/* Initialize structure containing state of computation.
(RFC 1321, 3.3: Step 3) */
void
__md5_init_ctx (struct md5_ctx *ctx)
{
ctx->A = 0x67452301;
ctx->B = 0xefcdab89;
ctx->C = 0x98badcfe;
ctx->D = 0x10325476;
ctx->total[0] = ctx->total[1] = 0;
ctx->buflen = 0;
}
/* Put result from CTX in first 16 bytes following RESBUF. The result
must be in little endian byte order.
IMPORTANT: On some systems it is required that RESBUF is correctly
aligned for a 32 bits value. */
void *
__md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
{
((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
return resbuf;
}
/* Process the remaining bytes in the internal buffer and the usual
prolog according to the standard and write the result to RESBUF.
IMPORTANT: On some systems it is required that RESBUF is correctly
aligned for a 32 bits value. */
void *
__md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
{
/* Take yet unprocessed bytes into account. */
md5_uint32 bytes = ctx->buflen;
size_t pad;
/* Now count remaining bytes. */
ctx->total[0] += bytes;
if (ctx->total[0] < bytes)
++ctx->total[1];
pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
memcpy (&ctx->buffer[bytes], fillbuf, pad);
/* Put the 64-bit file length in *bits* at the end of the buffer. */
ctx->buffer32[(bytes + pad) / 4] = SWAP (ctx->total[0] << 3);
ctx->buffer32[(bytes + pad + 4) / 4] = SWAP ((ctx->total[1] << 3)
| (ctx->total[0] >> 29));
/* Process last bytes. */
__md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
return __md5_read_ctx (ctx, resbuf);
}
/* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
result is always in little endian byte order, so that a byte-wise
output yields to the wanted ASCII representation of the message
digest. */
void *
__md5_buffer (const char *buffer, size_t len, void *resblock)
{
struct md5_ctx ctx;
/* Initialize the computation context. */
__md5_init_ctx (&ctx);
/* Process whole buffer but last len % 64 bytes. */
__md5_process_bytes (buffer, len, &ctx);
/* Put result in desired memory area. */
return __md5_finish_ctx (&ctx, resblock);
}
void
__md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
{
/* When we already have some bits in our internal buffer concatenate
both inputs first. */
if (ctx->buflen != 0)
{
size_t left_over = ctx->buflen;
size_t add = 128 - left_over > len ? len : 128 - left_over;
memcpy (&ctx->buffer[left_over], buffer, add);
ctx->buflen += add;
if (ctx->buflen > 64)
{
__md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
ctx->buflen &= 63;
/* The regions in the following copy operation cannot overlap. */
memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
ctx->buflen);
}
buffer = (const char *) buffer + add;
len -= add;
}
/* Process available complete blocks. */
if (len >= 64)
{
while (len > 64)
{
__md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
buffer = (const char *) buffer + 64;
len -= 64;
}
}
/* Move remaining bytes in internal buffer. */
if (len > 0)
{
size_t left_over = ctx->buflen;
memcpy (&ctx->buffer[left_over], buffer, len);
left_over += len;
if (left_over >= 64)
{
__md5_process_block (ctx->buffer, 64, ctx);
left_over -= 64;
memcpy (ctx->buffer, &ctx->buffer[64], left_over);
}
ctx->buflen = left_over;
}
}
#include <md5-block.c>
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