/*
 * Based on the Mozilla SHA1 (see mozilla-sha1/sha1.c),
 * optimized to do word accesses rather than byte accesses,
 * and to avoid unnecessary copies into the context array.
 */

#include <string.h>
#include <arpa/inet.h>

#include "sha1.h"

/* Hash one 64-byte block of data */
static void blk_SHA1Block(blk_SHA_CTX *ctx, const unsigned int *data);

void blk_SHA1_Init(blk_SHA_CTX *ctx)
{
	ctx->lenW = 0;
	ctx->size = 0;

	/* Initialize H with the magic constants (see FIPS180 for constants)
	 */
	ctx->H[0] = 0x67452301;
	ctx->H[1] = 0xefcdab89;
	ctx->H[2] = 0x98badcfe;
	ctx->H[3] = 0x10325476;
	ctx->H[4] = 0xc3d2e1f0;
}


void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len)
{
	int lenW = ctx->lenW;

	ctx->size += (unsigned long long) len << 3;

	/* Read the data into W and process blocks as they get full
	 */
	if (lenW) {
		int left = 64 - lenW;
		if (len < left)
			left = len;
		memcpy(lenW + (char *)ctx->W, data, left);
		lenW = (lenW + left) & 63;
		len -= left;
		data += left;
		ctx->lenW = lenW;
		if (lenW)
			return;
		blk_SHA1Block(ctx, ctx->W);
	}
	while (len >= 64) {
		blk_SHA1Block(ctx, data);
		data += 64;
		len -= 64;
	}
	if (len) {
		memcpy(ctx->W, data, len);
		ctx->lenW = len;
	}
}


void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
{
	static const unsigned char pad[64] = { 0x80 };
	unsigned int padlen[2];
	int i;

	/* Pad with a binary 1 (ie 0x80), then zeroes, then length
	 */
	padlen[0] = htonl(ctx->size >> 32);
	padlen[1] = htonl(ctx->size);

	blk_SHA1_Update(ctx, pad, 1+ (63 & (55 - ctx->lenW)));
	blk_SHA1_Update(ctx, padlen, 8);

	/* Output hash
	 */
	for (i = 0; i < 5; i++)
		((unsigned int *)hashout)[i] = htonl(ctx->H[i]);
}

#define SHA_ROT(X,n) (((X) << (n)) | ((X) >> (32-(n))))

static void blk_SHA1Block(blk_SHA_CTX *ctx, const unsigned int *data)
{
	int t;
	unsigned int A,B,C,D,E,TEMP;
	unsigned int W[80];

	for (t = 0; t < 16; t++)
		W[t] = htonl(data[t]);

	/* Unroll it? */
	for (t = 16; t <= 79; t++)
		W[t] = SHA_ROT(W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16], 1);

	A = ctx->H[0];
	B = ctx->H[1];
	C = ctx->H[2];
	D = ctx->H[3];
	E = ctx->H[4];

#define T_0_19(t) \
	TEMP = SHA_ROT(A,5) + (((C^D)&B)^D)     + E + W[t] + 0x5a827999; \
	E = D; D = C; C = SHA_ROT(B, 30); B = A; A = TEMP;

	T_0_19( 0); T_0_19( 1); T_0_19( 2); T_0_19( 3); T_0_19( 4);
	T_0_19( 5); T_0_19( 6); T_0_19( 7); T_0_19( 8); T_0_19( 9);
	T_0_19(10); T_0_19(11); T_0_19(12); T_0_19(13); T_0_19(14);
	T_0_19(15); T_0_19(16); T_0_19(17); T_0_19(18); T_0_19(19);

#define T_20_39(t) \
	TEMP = SHA_ROT(A,5) + (B^C^D)           + E + W[t] + 0x6ed9eba1; \
	E = D; D = C; C = SHA_ROT(B, 30); B = A; A = TEMP;

	T_20_39(20); T_20_39(21); T_20_39(22); T_20_39(23); T_20_39(24);
	T_20_39(25); T_20_39(26); T_20_39(27); T_20_39(28); T_20_39(29);
	T_20_39(30); T_20_39(31); T_20_39(32); T_20_39(33); T_20_39(34);
	T_20_39(35); T_20_39(36); T_20_39(37); T_20_39(38); T_20_39(39);

#define T_40_59(t) \
	TEMP = SHA_ROT(A,5) + ((B&C)|(D&(B|C))) + E + W[t] + 0x8f1bbcdc; \
	E = D; D = C; C = SHA_ROT(B, 30); B = A; A = TEMP;

	T_40_59(40); T_40_59(41); T_40_59(42); T_40_59(43); T_40_59(44);
	T_40_59(45); T_40_59(46); T_40_59(47); T_40_59(48); T_40_59(49);
	T_40_59(50); T_40_59(51); T_40_59(52); T_40_59(53); T_40_59(54);
	T_40_59(55); T_40_59(56); T_40_59(57); T_40_59(58); T_40_59(59);

#define T_60_79(t) \
	TEMP = SHA_ROT(A,5) + (B^C^D)           + E + W[t] + 0xca62c1d6; \
	E = D; D = C; C = SHA_ROT(B, 30); B = A; A = TEMP;

	T_60_79(60); T_60_79(61); T_60_79(62); T_60_79(63); T_60_79(64);
	T_60_79(65); T_60_79(66); T_60_79(67); T_60_79(68); T_60_79(69);
	T_60_79(70); T_60_79(71); T_60_79(72); T_60_79(73); T_60_79(74);
	T_60_79(75); T_60_79(76); T_60_79(77); T_60_79(78); T_60_79(79);

	ctx->H[0] += A;
	ctx->H[1] += B;
	ctx->H[2] += C;
	ctx->H[3] += D;
	ctx->H[4] += E;
}