/* sha1.c - Functions to compute SHA1 message digest of files or
   memory blocks according to the NIST specification FIPS-180-1.

   Copyright (C) 2000-2001, 2003-2006, 2008-2011 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the
   Free Software Foundation; either version 3, or (at your option) any
   later version.

   This program 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 a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/* Written by Scott G. Miller
   Credits:
      Robert Klep <robert@ilse.nl>  -- Expansion function fix

   Modified by Eric Biggers for wimlib:  Conditionally compile in the use of
   OpenSSL or Intel's assembly code for SHA1 block updates
*/

#include "util.h"
#include "wimlib.h"
#include "sha1.h"
#include "endianness.h"
#include <string.h>

#define SWAP(n) to_be32(n)

#define BLOCKSIZE 32768
#if BLOCKSIZE % 64 != 0
#error "invalid BLOCKSIZE"
#endif


#ifdef WITH_LIBCRYPTO

static inline void sha1_init_ctx(SHA_CTX *ctx)
{
	SHA1_Init(ctx);
}

static inline void sha1_process_block(const void *buffer, size_t len, 
				      SHA_CTX *ctx)
{
	SHA1_Update(ctx, buffer, len);
}

static inline void sha1_process_bytes(const void *buffer, size_t len, 
				      SHA_CTX *ctx)
{
	SHA1_Update(ctx, buffer, len);
}


static inline void *sha1_finish_ctx(SHA_CTX *ctx, void *resbuf)
{
	SHA1_Final(resbuf, ctx);
}
#else /* WITH_LIBCRYPTO */

/* Structure to save state of computation between the single steps.  */
struct sha1_ctx {
	uint32_t A;
	uint32_t B;
	uint32_t C;
	uint32_t D;
	uint32_t E;

	uint32_t total[2];
	uint32_t buflen;
	uint32_t buffer[32];
};

typedef struct sha1_ctx SHA_CTX;

#ifdef ENABLE_SSSE3_SHA1
extern void sha1_update_intel(int *hash, const char* input, size_t num_blocks);

static inline void sha1_process_block(const void *buffer, size_t len, 
				      SHA_CTX *ctx)
{
	sha1_update_intel((int*)ctx, buffer, len / 64);
	ctx->total[0] += len;
	if (ctx->total[0] < len)
		++ctx->total[1];
}

#include <stdlib.h>
void ssse3_not_found()
{
	fprintf(stderr, 
"Cannot calculate SHA1 message digest: CPU does not support SSSE3\n"
"instructions!  Recompile wimlib without the --enable-ssse3-sha1 flag\n"
"to use wimlib on this CPU.\n");
	abort();
}
#else /* ENABLE_SSSE3_SHA1 */

static void sha1_process_block(const void *buffer, size_t len,
			       SHA_CTX *ctx);

#endif /* ENABLE_SSSE3_SHA1 */


/* This array contains the bytes used to pad the buffer to the next
   64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
static const u8 fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */  };

/* Initialize structure containing state of computation. */
static void sha1_init_ctx(SHA_CTX *ctx);

/* Starting with the result of former calls of this function (or the
   initialization function update the context for the next LEN bytes
   starting at BUFFER.
   It is NOT required that LEN is a multiple of 64.  */
static void sha1_process_bytes(const void *buffer, size_t len,
			       SHA_CTX *ctx);

/* Process the remaining bytes in the buffer and put result from CTX
   in first 20 bytes following RESBUF.  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.  */
static void *sha1_finish_ctx(SHA_CTX *ctx, void *resbuf);

/* Put result from CTX in first 20 bytes following RESBUF.  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.  */
static void *sha1_read_ctx(const SHA_CTX *ctx, void *resbuf);

#endif /* WITH_LIBCRYPTO */



/* Compute SHA1 message digest for bytes read from STREAM.  The resulting
 * message digest number will be written into the 20 bytes beginning at
 * RESBLOCK.  */
int sha1_stream(FILE * stream, void *resblock)
{
	SHA_CTX ctx;

	size_t sum;

	char *buffer = MALLOC(BLOCKSIZE + 72);
	if (!buffer) {
		ERROR("Out of memory!\n");
		return WIMLIB_ERR_NOMEM;
	}

	/* Initialize the computation context.  */
	sha1_init_ctx(&ctx);

	/* Iterate over full file contents.  */
	while (1) {
		/* We read the file in blocks of BLOCKSIZE bytes.  One call of the
		   computation function processes the whole buffer so that with the
		   next round of the loop another block can be read.  */
		size_t n;
		sum = 0;

		/* Read block.  Take care for partial reads.  */
		while (1) {
			n = fread(buffer + sum, 1, BLOCKSIZE - sum, stream);

			sum += n;

			if (sum == BLOCKSIZE)
				break;

			if (n == 0) {
				/* Check for the error flag IFF N == 0, so that
				 * we don't exit the loop after a partial read
				 * due to e.g., EAGAIN or EWOULDBLOCK.  */
				if (ferror(stream)) {
					FREE(buffer);
					ERROR("Read error while calculating "
						"SHA1 message digest: %m\n");
					return WIMLIB_ERR_READ;
				}
				goto process_partial_block;
			}

			/* We've read at least one byte, so ignore errors.  But always
			   check for EOF, since feof may be true even though N > 0.
			   Otherwise, we could end up calling fread after EOF.  */
			if (feof(stream))
				goto process_partial_block;
		}

		/* Process buffer with BLOCKSIZE bytes.  Note that
		   BLOCKSIZE % 64 == 0
		 */
		sha1_process_block(buffer, BLOCKSIZE, &ctx);
	}

 process_partial_block:;

	/* Process any remaining bytes.  */
	if (sum > 0)
		sha1_process_bytes(buffer, sum, &ctx);

	/* Construct result in desired memory.  */
	sha1_finish_ctx(&ctx, resblock);
	FREE(buffer);
	return 0;
}

#ifndef WITH_LIBCRYPTO
/* Compute SHA1 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 *sha1_buffer(const char *buffer, size_t len, void *resblock)
{
	SHA_CTX ctx;

	/* Initialize the computation context.  */
	sha1_init_ctx(&ctx);

	/* Process whole buffer but last len % 64 bytes.  */
	sha1_process_bytes(buffer, len, &ctx);

	/* Put result in desired memory area.  */
	return sha1_finish_ctx(&ctx, resblock);
}

/* Take a pointer to a 160 bit block of data (five 32 bit ints) and
   initialize it to the start constants of the SHA1 algorithm.  This
   must be called before using hash in the call to sha1_hash.  */
static void sha1_init_ctx(SHA_CTX *ctx)
{
	ctx->A = 0x67452301;
	ctx->B = 0xefcdab89;
	ctx->C = 0x98badcfe;
	ctx->D = 0x10325476;
	ctx->E = 0xc3d2e1f0;

	ctx->total[0] = ctx->total[1] = 0;
	ctx->buflen = 0;
}

/* Copy the 4 byte value from v into the memory location pointed to by *cp,
   If your architecture allows unaligned access this is equivalent to
   * (uint32_t *) cp = v  */
static inline void set_uint32(char *cp, uint32_t v)
{
	memcpy(cp, &v, sizeof v);
}

/* Put result from CTX in first 20 bytes following RESBUF.  The result
   must be in little endian byte order.  */
static void *sha1_read_ctx(const SHA_CTX *ctx, void *resbuf)
{
	char *r = resbuf;
	set_uint32(r + 0 * sizeof ctx->A, SWAP(ctx->A));
	set_uint32(r + 1 * sizeof ctx->B, SWAP(ctx->B));
	set_uint32(r + 2 * sizeof ctx->C, SWAP(ctx->C));
	set_uint32(r + 3 * sizeof ctx->D, SWAP(ctx->D));
	set_uint32(r + 4 * sizeof ctx->E, SWAP(ctx->E));

	return resbuf;
}

/* Process the remaining bytes in the internal buffer and the usual
   prolog according to the standard and write the result to RESBUF.  */
static void *sha1_finish_ctx(SHA_CTX *ctx, void *resbuf)
{
	/* Take yet unprocessed bytes into account.  */
	uint32_t bytes = ctx->buflen;
	size_t size = (bytes < 56) ? 64 / 4 : 64 * 2 / 4;

	/* Now count remaining bytes.  */
	ctx->total[0] += bytes;
	if (ctx->total[0] < bytes)
		++ctx->total[1];

	/* Put the 64-bit file length in *bits* at the end of the buffer.  */
	ctx->buffer[size - 2] =
	    SWAP((ctx->total[1] << 3) | (ctx->total[0] >> 29));
	ctx->buffer[size - 1] = SWAP(ctx->total[0] << 3);

	memcpy(&((char *)ctx->buffer)[bytes], fillbuf, (size - 2) * 4 - bytes);

	/* Process last bytes.  */
	sha1_process_block(ctx->buffer, size * 4, ctx);

	return sha1_read_ctx(ctx, resbuf);
}


static void sha1_process_bytes(const void *buffer, size_t len, SHA_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(&((char *)ctx->buffer)[left_over], buffer, add);
		ctx->buflen += add;

		if (ctx->buflen > 64) {
			sha1_process_block(ctx->buffer, ctx->buflen & ~63, ctx);

			ctx->buflen &= 63;
			/* The regions in the following copy operation cannot overlap.  */
			memcpy(ctx->buffer,
			       &((char *)ctx->buffer)[(left_over + add) & ~63],
			       ctx->buflen);
		}

		buffer = (const char *)buffer + add;
		len -= add;
	}

	/* Process available complete blocks.  */
	if (len >= 64) {
#if !_STRING_ARCH_unaligned
#define alignof(type) offsetof (struct { char c; type x; }, x)
#define UNALIGNED_P(p) (((size_t) p) % alignof (uint32_t) != 0)
		if (UNALIGNED_P(buffer))
			while (len > 64) {
				sha1_process_block(memcpy
						   (ctx->buffer, buffer, 64),
						   64, ctx);
				buffer = (const char *)buffer + 64;
				len -= 64;
		} else
#endif
		{
			sha1_process_block(buffer, len & ~63, ctx);
			buffer = (const char *)buffer + (len & ~63);
			len &= 63;
		}
	}

	/* Move remaining bytes in internal buffer.  */
	if (len > 0) {
		size_t left_over = ctx->buflen;

		memcpy(&((char *)ctx->buffer)[left_over], buffer, len);
		left_over += len;
		if (left_over >= 64) {
			sha1_process_block(ctx->buffer, 64, ctx);
			left_over -= 64;
			memcpy(ctx->buffer, &ctx->buffer[16], left_over);
		}
		ctx->buflen = left_over;
	}
}

/* --- Code below is the primary difference between md5.c and sha1.c --- */

/* SHA1 round constants */
#define K1 0x5a827999
#define K2 0x6ed9eba1
#define K3 0x8f1bbcdc
#define K4 0xca62c1d6

/* Round functions.  Note that F2 is the same as F4.  */
#define F1(B,C,D) ( D ^ ( B & ( C ^ D ) ) )
#define F2(B,C,D) (B ^ C ^ D)
#define F3(B,C,D) ( ( B & C ) | ( D & ( B | C ) ) )
#define F4(B,C,D) (B ^ C ^ D)

/* Process LEN bytes of BUFFER, accumulating context into CTX.
   It is assumed that LEN % 64 == 0.
   Most of this code comes from GnuPG's cipher/sha1.c.  */

#ifndef ENABLE_SSSE3_SHA1
static void sha1_process_block(const void *buffer, size_t len, SHA_CTX *ctx)
{
	const uint32_t *words = buffer;
	size_t nwords = len / sizeof(uint32_t);
	const uint32_t *endp = words + nwords;
	uint32_t x[16];
	uint32_t a = ctx->A;
	uint32_t b = ctx->B;
	uint32_t c = ctx->C;
	uint32_t d = ctx->D;
	uint32_t e = ctx->E;

	/* First increment the byte count.  RFC 1321 specifies the possible
	   length of the file up to 2^64 bits.  Here we only compute the
	   number of bytes.  Do a double word increment.  */
	ctx->total[0] += len;
	if (ctx->total[0] < len)
		++ctx->total[1];

#define rol(x, n) (((x) << (n)) | ((uint32_t) (x) >> (32 - (n))))

#define M(I) ( tm =   x[I&0x0f] ^ x[(I-14)&0x0f] \
                    ^ x[(I-8)&0x0f] ^ x[(I-3)&0x0f] \
               , (x[I&0x0f] = rol(tm, 1)) )

#define R(A,B,C,D,E,F,K,M)  do { E += rol( A, 5 )     \
                                      + F( B, C, D )  \
                                      + K             \
                                      + M;            \
                                 B = rol( B, 30 );    \
                               } while(0)

	while (words < endp) {
		uint32_t tm;
		int t;
		for (t = 0; t < 16; t++) {
			x[t] = SWAP(*words);
			words++;
		}

		R(a, b, c, d, e, F1, K1, x[0]);
		R(e, a, b, c, d, F1, K1, x[1]);
		R(d, e, a, b, c, F1, K1, x[2]);
		R(c, d, e, a, b, F1, K1, x[3]);
		R(b, c, d, e, a, F1, K1, x[4]);
		R(a, b, c, d, e, F1, K1, x[5]);
		R(e, a, b, c, d, F1, K1, x[6]);
		R(d, e, a, b, c, F1, K1, x[7]);
		R(c, d, e, a, b, F1, K1, x[8]);
		R(b, c, d, e, a, F1, K1, x[9]);
		R(a, b, c, d, e, F1, K1, x[10]);
		R(e, a, b, c, d, F1, K1, x[11]);
		R(d, e, a, b, c, F1, K1, x[12]);
		R(c, d, e, a, b, F1, K1, x[13]);
		R(b, c, d, e, a, F1, K1, x[14]);
		R(a, b, c, d, e, F1, K1, x[15]);
		R(e, a, b, c, d, F1, K1, M(16));
		R(d, e, a, b, c, F1, K1, M(17));
		R(c, d, e, a, b, F1, K1, M(18));
		R(b, c, d, e, a, F1, K1, M(19));
		R(a, b, c, d, e, F2, K2, M(20));
		R(e, a, b, c, d, F2, K2, M(21));
		R(d, e, a, b, c, F2, K2, M(22));
		R(c, d, e, a, b, F2, K2, M(23));
		R(b, c, d, e, a, F2, K2, M(24));
		R(a, b, c, d, e, F2, K2, M(25));
		R(e, a, b, c, d, F2, K2, M(26));
		R(d, e, a, b, c, F2, K2, M(27));
		R(c, d, e, a, b, F2, K2, M(28));
		R(b, c, d, e, a, F2, K2, M(29));
		R(a, b, c, d, e, F2, K2, M(30));
		R(e, a, b, c, d, F2, K2, M(31));
		R(d, e, a, b, c, F2, K2, M(32));
		R(c, d, e, a, b, F2, K2, M(33));
		R(b, c, d, e, a, F2, K2, M(34));
		R(a, b, c, d, e, F2, K2, M(35));
		R(e, a, b, c, d, F2, K2, M(36));
		R(d, e, a, b, c, F2, K2, M(37));
		R(c, d, e, a, b, F2, K2, M(38));
		R(b, c, d, e, a, F2, K2, M(39));
		R(a, b, c, d, e, F3, K3, M(40));
		R(e, a, b, c, d, F3, K3, M(41));
		R(d, e, a, b, c, F3, K3, M(42));
		R(c, d, e, a, b, F3, K3, M(43));
		R(b, c, d, e, a, F3, K3, M(44));
		R(a, b, c, d, e, F3, K3, M(45));
		R(e, a, b, c, d, F3, K3, M(46));
		R(d, e, a, b, c, F3, K3, M(47));
		R(c, d, e, a, b, F3, K3, M(48));
		R(b, c, d, e, a, F3, K3, M(49));
		R(a, b, c, d, e, F3, K3, M(50));
		R(e, a, b, c, d, F3, K3, M(51));
		R(d, e, a, b, c, F3, K3, M(52));
		R(c, d, e, a, b, F3, K3, M(53));
		R(b, c, d, e, a, F3, K3, M(54));
		R(a, b, c, d, e, F3, K3, M(55));
		R(e, a, b, c, d, F3, K3, M(56));
		R(d, e, a, b, c, F3, K3, M(57));
		R(c, d, e, a, b, F3, K3, M(58));
		R(b, c, d, e, a, F3, K3, M(59));
		R(a, b, c, d, e, F4, K4, M(60));
		R(e, a, b, c, d, F4, K4, M(61));
		R(d, e, a, b, c, F4, K4, M(62));
		R(c, d, e, a, b, F4, K4, M(63));
		R(b, c, d, e, a, F4, K4, M(64));
		R(a, b, c, d, e, F4, K4, M(65));
		R(e, a, b, c, d, F4, K4, M(66));
		R(d, e, a, b, c, F4, K4, M(67));
		R(c, d, e, a, b, F4, K4, M(68));
		R(b, c, d, e, a, F4, K4, M(69));
		R(a, b, c, d, e, F4, K4, M(70));
		R(e, a, b, c, d, F4, K4, M(71));
		R(d, e, a, b, c, F4, K4, M(72));
		R(c, d, e, a, b, F4, K4, M(73));
		R(b, c, d, e, a, F4, K4, M(74));
		R(a, b, c, d, e, F4, K4, M(75));
		R(e, a, b, c, d, F4, K4, M(76));
		R(d, e, a, b, c, F4, K4, M(77));
		R(c, d, e, a, b, F4, K4, M(78));
		R(b, c, d, e, a, F4, K4, M(79));

		a = ctx->A += a;
		b = ctx->B += b;
		c = ctx->C += c;
		d = ctx->D += d;
		e = ctx->E += e;
	}
}
#endif /* ENABLE_SSSE3_SHA1 */

#endif /* WITH_LIBCRYPTO */