/*
	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
*/

/* #define LITTLE_ENDIAN * This should be #define'd if true. */
/* #define SHA1HANDSOFF * Copies data before messing with it. */
#include <tcl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include <fcntl.h>
#include <stdio.h>

#define SHA1HANDSOFF 1

typedef struct {
	uint32_t state[5];
	uint32_t count[2];
	uint8_t  buffer[64];
} SHA1_CTX;

#ifndef __BIG_ENDIAN
#define __BIG_ENDIAN 4321
#endif
#ifndef __LITTLE_ENDIAN
#define __LITTLE_ENDIAN 1234
#endif

#ifndef __BYTE_ORDER
#ifdef WORDS_BIGENDIAN
#define __BYTE_ORDER __BIG_ENDIAN
#else
#define __BYTE_ORDER __LITTLE_ENDIAN
#endif
#endif

#if __BYTE_ORDER == __BIG_ENDIAN
#ifndef BIG_ENDIAN
#define BIG_ENDIAN 1
#endif
#undef LITTLE_ENDIAN
#else
#ifndef LITTLE_ENDIAN
#define LITTLE_ENDIAN 1
#endif
#undef BIG_ENDIAN
#endif

#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 LITTLE_ENDIAN
#define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) \
    |(rol(block->l[i],8)&0x00FF00FF))
#else
#define blk0(i) block->l[i]
#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 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. */

static void SHA1Transform(uint32_t state[5], uint8_t buffer[64]) {
	uint32_t a, b, c, d, e;
	typedef union {
		uint8_t  c[64];
		uint32_t l[16];
	} CHAR64LONG16;
	CHAR64LONG16* block;
#ifdef SHA1HANDSOFF
	uint8_t workspace[sizeof(*block)];

	block = (CHAR64LONG16*)workspace;
	memcpy(block, buffer, sizeof(*block));
#else
	block = (CHAR64LONG16*)buffer;
#endif

	/* 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 */
static void SHA1Init(SHA1_CTX* context) {
	/* SHA1 initialization constants */
	context->state[0] = 0x67452301;
	context->state[1] = 0xEFCDAB89;
	context->state[2] = 0x98BADCFE;
	context->state[3] = 0x10325476;
	context->state[4] = 0xC3D2E1F0;
	context->count[0] = 0;
	context->count[1] = 0;
}


/* Run your data through this. */
static void SHA1Update(SHA1_CTX* context, unsigned char* data, unsigned int len) {
	unsigned int i, j;

	j = (context->count[0] >> 3) & 63;
	if ((context->count[0] += len << 3) < (len << 3)) {
		context->count[1]++;
	}

	context->count[1] += (len >> 29);

	if ((j + len) > 63) {
		memcpy(&context->buffer[j], data, (i = 64-j));
		SHA1Transform(context->state, context->buffer);
		for ( ; i + 63 < len; i += 64) {
			SHA1Transform(context->state, &data[i]);
		}
		j = 0;
	} else {
		i = 0;
	}

	memcpy(&context->buffer[j], &data[i], len - i);
}


/* Add padding and return the message digest. */
static void SHA1Final(unsigned char digest[20], SHA1_CTX* context) {
	unsigned long i;
	unsigned char finalcount[8];

	for (i = 0; i < 8; i++) {
		finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)] >> ((3-(i & 3)) * 8) ) & 255);  /* Endian independent */
	}

	SHA1Update(context, (unsigned char *) "\200", 1);

	while ((context->count[0] & 504) != 448) {
		SHA1Update(context, (unsigned char *)"\0", 1);
	}

	SHA1Update(context, finalcount, 8);  /* Should cause a SHA1Transform() */
	for (i = 0; i < 20; i++) {
		digest[i] = (unsigned char) ((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
	}

	/* Wipe variables */
	i = 0;

	memset(context->buffer, 0, 64);
	memset(context->state, 0, 20);
	memset(context->count, 0, 8);
	memset(&finalcount, 0, 8);
#ifdef SHA1HANDSOFF  /* make SHA1Transform overwrite it's own static vars */
	SHA1Transform(context->state, context->buffer);
#endif
}

static Tcl_Obj* c_sha1__sha1_file(char* file) {
	SHA1_CTX ctx;
	unsigned char digest[20];
	unsigned char buf[4096];
	int fd;
	ssize_t read_ret;
	Tcl_Obj *ret;

	fd = open(file, O_RDONLY);
	if (fd < 0) {
		return(NULL);
	}

	SHA1Init(&ctx);

	while (1) {
		read_ret = read(fd, buf, sizeof(buf));

		if (read_ret == 0) {
			break;
		}

		if (read_ret < 0) {
			close(fd);

			return(NULL);
		}

		SHA1Update(&ctx, buf, read_ret);
	}

	close(fd);

	SHA1Final(digest, &ctx);

	ret = Tcl_NewByteArrayObj(digest, sizeof(digest));

	return(ret);
}

static int tcl_sha1__sha1_file(ClientData dummy, Tcl_Interp *ip, int objc, Tcl_Obj *CONST objv[]) {
	char* _file;
	Tcl_Obj* rv;
	if (objc != 2) {
		Tcl_WrongNumArgs(ip, 1, objv, "file");
		return TCL_ERROR;
	}
	_file = Tcl_GetString(objv[1]);

	rv = c_sha1__sha1_file(_file);
	if (rv == NULL) {
		return(TCL_ERROR);
	}
	Tcl_SetObjResult(ip, rv);
	return TCL_OK;
}

static Tcl_Obj* c_sha1__sha1_string(Tcl_Obj* str) {
	SHA1_CTX ctx;
	unsigned char digest[20];
	unsigned char *buf;
	int buf_len;
	Tcl_Obj *ret;

	SHA1Init(&ctx);

	buf = Tcl_GetByteArrayFromObj(str, &buf_len);
	if (buf == NULL) {
		return(NULL);
	}

	SHA1Update(&ctx, buf, buf_len);

	SHA1Final(digest, &ctx);

	ret = Tcl_NewByteArrayObj(digest, sizeof(digest));

	return(ret);
}

static int tcl_sha1__sha1_string(ClientData dummy, Tcl_Interp *ip, int objc, Tcl_Obj *CONST objv[]) {
	Tcl_Obj* _str;
	Tcl_Obj* rv;
	if (objc != 2) {
		Tcl_WrongNumArgs(ip, 1, objv, "str");
		return TCL_ERROR;
	}
	_str = objv[1];

	rv = c_sha1__sha1_string(_str);
	if (rv == NULL) {
		return(TCL_ERROR);
	}
	Tcl_SetObjResult(ip, rv);
	return TCL_OK;
}

int Sha1_Init(Tcl_Interp *interp) {
#ifdef USE_TCL_STUBS
	if (Tcl_InitStubs(interp, TCL_VERSION, 0) == 0L) {
		return TCL_ERROR;
	}
#endif
	Tcl_CreateObjCommand(interp, "sha1::_sha1_file", tcl_sha1__sha1_file, NULL, NULL);
	Tcl_CreateObjCommand(interp, "sha1::_sha1_string", tcl_sha1__sha1_string, NULL, NULL);
	Tcl_Eval(interp,
#include "sha1.tcl.h"
	);
	Tcl_PkgProvide(interp, "sha1", "1.0");
	return(TCL_OK);
}
