/*
 * pgcrypto.c
 *		Cryptographic digests for PostgreSQL.
 * 
 * Copyright (c) 2000 Marko Kreen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $Id: pgcrypto.c,v 1.2 2000/11/20 20:36:56 tgl Exp $
 */

#include <postgres.h>
#include <utils/builtins.h>

#include "pgcrypto.h"

/*
 * maximum length of digest for internal buffers
 */
#define MAX_DIGEST_LENGTH	128

/*
 * NAMEDATALEN is used for hash names
 */
#if NAMEDATALEN < 16
#error "NAMEDATALEN < 16: too small"
#endif


/* exported functions */
Datum digest(PG_FUNCTION_ARGS);
Datum digest_exists(PG_FUNCTION_ARGS);

/* private stuff */
static char *
to_hex(uint8 *src, uint len, char *dst);
static pg_digest *
find_digest(pg_digest *hbuf, text *name, int silent);


/* SQL function: hash(text, text) returns text */
PG_FUNCTION_INFO_V1(digest);

Datum
digest(PG_FUNCTION_ARGS)
{
	text *arg;
	text *name;
	uint8 *p, buf[MAX_DIGEST_LENGTH];
	uint len, hlen;
	pg_digest *h, _hbuf;
	text *res;
	
	if (PG_ARGISNULL(0) || PG_ARGISNULL(1))
		PG_RETURN_NULL();
	
	name = PG_GETARG_TEXT_P(1);	
	h = find_digest(&_hbuf, name, 0); /* will give error if fails */

	hlen = h->length(h);
	if (hlen > MAX_DIGEST_LENGTH)
		elog(ERROR, "Hash length overflow: %d", hlen);
	
	res = (text *)palloc(hlen*2 + VARHDRSZ);
	VARATT_SIZEP(res) = hlen*2 + VARHDRSZ;
	
	arg = PG_GETARG_TEXT_P(0);
	len = VARSIZE(arg) - VARHDRSZ;
	
	p = h->digest(h, VARDATA(arg), len, buf);
	to_hex(p, hlen, VARDATA(res));
	
	PG_FREE_IF_COPY(arg, 0);
	PG_FREE_IF_COPY(name, 0);	// unnecessary i guess
	
	PG_RETURN_TEXT_P(res);
}

/* check if given hash exists */
PG_FUNCTION_INFO_V1(digest_exists);

Datum
digest_exists(PG_FUNCTION_ARGS)
{
	text *name;
	pg_digest _hbuf, *res;

	if (PG_ARGISNULL(0))
		PG_RETURN_NULL();
	
	name = PG_GETARG_TEXT_P(0);
	
	res = find_digest(&_hbuf, name, 1);
	
	PG_FREE_IF_COPY(name, 0);	// unnecessary i guess

	if (res != NULL)
		PG_RETURN_BOOL(true);
	PG_RETURN_BOOL(false);
}

static pg_digest *
find_digest(pg_digest *hbuf, text *name, int silent)
{
	pg_digest *p;
	char buf[NAMEDATALEN];
	uint len;
	
	len = VARSIZE(name) - VARHDRSZ;
	if (len >= NAMEDATALEN) {
		if (silent)
			return NULL;
		elog(ERROR, "Hash type does not exist (name too long)");
	}
		
	memcpy(buf, VARDATA(name), len);
	buf[len] = 0;
	
	p = pg_find_digest(hbuf, buf);

	if (p == NULL && !silent)
		elog(ERROR, "Hash type does not exist: '%s'", buf);
	return p;
}

static unsigned char *hextbl = "0123456789abcdef";

/* dumps binary to hex...  Note that it does not null-terminate  */
static char *
to_hex(uint8 *buf, uint len, char *dst)
{
	uint i;
	for (i = 0; i < len; i++) {
		dst[i*2] = hextbl[(buf[i] >> 4) & 0xF];
		dst[i*2 + 1] = hextbl[buf[i] & 0xF];
	}
	return dst;
}