/*
 * SHA-1 in C
 * By Steve Reid <steve@edmweb.com>
 * 100% Public Domain
 *
 * Test Vectors (from FIPS PUB 180-1)
 * "abc"
 *   A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D
 * "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
 *   84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1
 * A million repetitions of "a"
 *   34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F
 */

/*
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@login.dkuug.dk> wrote this file.  As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 */

#include <agar/core/core.h>
#include <agar/core/sha1.h>

#include <string.h>

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

/*
 * blk0() and blk() perform the initial expand.
 * I got the idea of expanding during the round function from SSLeay
 */
#ifdef AG_BIG_ENDIAN
# define blk0(i) block->l[i]
#else
# define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) \
    |(rol(block->l[i],8)&0x00FF00FF))
#endif
#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
    ^block->l[(i+2)&15]^block->l[i&15],1))

/*
 * (R0+R1), R2, R3, R4 are the different operations (rounds) used in SHA1
 */
#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);

/*
 * Hash a single 512-bit block. This is the core of the algorithm.
 */
void
AG_SHA1Transform(Uint32 state[5], const Uint8 buffer[AG_SHA1_BLOCK_LENGTH])
{
	Uint32 a, b, c, d, e;
	Uint8 workspace[AG_SHA1_BLOCK_LENGTH];
	typedef union {
		Uint8 c[64];
		Uint32 l[16];
	} CHAR64LONG16;
	CHAR64LONG16 *block = (CHAR64LONG16 *)workspace;

	(void)memcpy(block, buffer, AG_SHA1_BLOCK_LENGTH);

	/* Copy context->state[] to working vars */
	a = state[0];
	b = state[1];
	c = state[2];
	d = state[3];
	e = state[4];

	/* 4 rounds of 20 operations each. Loop unrolled. */
	R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
	R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
	R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
	R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
	R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
	R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
	R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
	R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
	R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
	R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
	R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
	R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
	R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
	R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
	R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
	R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
	R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
	R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
	R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
	R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);

	/* Add the working vars back into context.state[] */
	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
	state[4] += e;

	/* Wipe variables */
	a = b = c = d = e = 0;
}


/*
 * SHA1Init - Initialize new context
 */
void
AG_SHA1Init(AG_SHA1_CTX *context)
{

	/* SHA1 initialization constants */
	context->count = 0;
	context->state[0] = 0x67452301;
	context->state[1] = 0xEFCDAB89;
	context->state[2] = 0x98BADCFE;
	context->state[3] = 0x10325476;
	context->state[4] = 0xC3D2E1F0;
}


/*
 * Run your data through this.
 */
void
AG_SHA1Update(AG_SHA1_CTX *context, const Uint8 *data, size_t len)
{
	size_t i, j;

	j = (size_t)((context->count >> 3) & 63);
	context->count += (len << 3);
	if ((j + len) > 63) {
		(void)memcpy(&context->buffer[j], data, (i = 64-j));
		AG_SHA1Transform(context->state, context->buffer);
		for ( ; i + 63 < len; i += 64)
			AG_SHA1Transform(context->state, (Uint8 *)&data[i]);
		j = 0;
	} else {
		i = 0;
	}
	(void)memcpy(&context->buffer[j], &data[i], len - i);
}


/*
 * Add padding and return the message digest.
 */
void
AG_SHA1Pad(AG_SHA1_CTX *context)
{
	Uint8 finalcount[8];
	Uint i;

	for (i = 0; i < 8; i++) {
		finalcount[i] = (Uint8)((context->count >>
		    ((7 - (i & 7)) * 8)) & 255);	/* Endian independent */
	}
	AG_SHA1Update(context, (Uint8 *)"\200", 1);
	while ((context->count & 504) != 448) {
		AG_SHA1Update(context, (Uint8 *)"\0", 1);
	}
	/* Should cause a SHA1Transform() */
	AG_SHA1Update(context, finalcount, 8);
}

void
AG_SHA1Final(Uint8 digest[AG_SHA1_DIGEST_LENGTH], AG_SHA1_CTX *context)
{
	Uint i;

	AG_SHA1Pad(context);
	if (digest) {
		for (i = 0; i < AG_SHA1_DIGEST_LENGTH; i++) {
			digest[i] = (Uint8)
			   ((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
		}
		memset(context, 0, sizeof(*context));
	}
}

char *
AG_SHA1End(AG_SHA1_CTX *ctx, char *buf)
{
	int i;
	Uint8 digest[AG_SHA1_DIGEST_LENGTH];
	static const char hex[] = "0123456789abcdef";

	if (buf == NULL &&
	    (buf = TryMalloc(AG_SHA1_DIGEST_STRING_LENGTH)) == NULL)
		return (NULL);

	AG_SHA1Final(digest, ctx);
	for (i = 0; i < AG_SHA1_DIGEST_LENGTH; i++) {
		buf[i + i] = hex[digest[i] >> 4];
		buf[i + i + 1] = hex[digest[i] & 0x0f];
	}
	buf[i + i] = '\0';
	memset(digest, 0, sizeof(digest));
	return (buf);
}

char *
AG_SHA1Data(const Uint8 *data, size_t len, char *buf)
{
	AG_SHA1_CTX ctx;

	AG_SHA1Init(&ctx);
	AG_SHA1Update(&ctx, data, len);
	return AG_SHA1End(&ctx, buf);
}
