/* $OpenBSD: prf.c,v 1.14 2004/05/23 18:17:56 hshoexer Exp $	 */
/* $EOM: prf.c,v 1.7 1999/05/02 12:50:29 niklas Exp $	 */

/*
 * Copyright (c) 1998 Niels Provos.  All rights reserved.
 * Copyright (c) 1999 Niklas Hallqvist.  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 ``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 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.
 */

/*
 * This code was written under funding by Ericsson Radio Systems.
 */

#include <sys/param.h>
#include <stdlib.h>
#include <string.h>

#include "sysdep.h"

#include "hash.h"
#include "log.h"
#include "prf.h"

void	prf_hash_init(struct prf_hash_ctx *);
void	prf_hash_update(struct prf_hash_ctx *, unsigned char *, unsigned int);
void	prf_hash_final(unsigned char *, struct prf_hash_ctx *);

/* PRF behaves likes a hash */

void
prf_hash_init(struct prf_hash_ctx *ctx)
{
	memcpy(ctx->hash->ctx, ctx->ctx, ctx->hash->ctxsize);
	memcpy(ctx->hash->ctx2, ctx->ctx2, ctx->hash->ctxsize);
}

void
prf_hash_update(struct prf_hash_ctx *ctx, unsigned char *data,
    unsigned int len)
{
	ctx->hash->Update(ctx->hash->ctx, data, len);
}

void
prf_hash_final(unsigned char *digest, struct prf_hash_ctx *ctx)
{
	ctx->hash->HMACFinal(digest, ctx->hash);
}

/*
 * Obtain a Pseudo-Random Function for us. At the moment this is
 * the HMAC version of a hash. See RFC-2104 for reference.
 */
struct prf *
prf_alloc(enum prfs type, int subtype, unsigned char *shared,
    unsigned int sharedsize)
{
	struct hash    *hash;
	struct prf     *prf;
	struct prf_hash_ctx *prfctx;

	switch (type) {
	case PRF_HMAC:
		hash = hash_get(subtype);
		if (!hash) {
			log_print("prf_alloc: unknown hash type %d", subtype);
			return 0;
		}
		break;
	default:
		log_print("prf_alloc: unknown PRF type %d", type);
		return 0;
	}

	prf = malloc(sizeof *prf);
	if (!prf) {
		log_error("prf_alloc: malloc (%lu) failed",
		    (unsigned long)sizeof *prf);
		return 0;
	}
	if (type == PRF_HMAC) {
		/* Obtain needed memory.  */
		prfctx = malloc(sizeof *prfctx);
		if (!prfctx) {
			log_error("prf_alloc: malloc (%lu) failed",
			    (unsigned long)sizeof *prfctx);
			goto cleanprf;
		}
		prf->prfctx = prfctx;

		prfctx->ctx = malloc(hash->ctxsize);
		if (!prfctx->ctx) {
			log_error("prf_alloc: malloc (%d) failed",
			    hash->ctxsize);
			goto cleanprfctx;
		}
		prfctx->ctx2 = malloc(hash->ctxsize);
		if (!prfctx->ctx2) {
			log_error("prf_alloc: malloc (%d) failed",
			    hash->ctxsize);
			free(prfctx->ctx);
			goto cleanprfctx;
		}
		prf->type = PRF_HMAC;
		prf->blocksize = hash->hashsize;
		prfctx->hash = hash;

		/* Use the correct function pointers.  */
		prf->Init = (void(*)(void *))prf_hash_init;
		prf->Update = (void(*)(void *, unsigned char *,
		    unsigned int))prf_hash_update;
		prf->Final = (void(*)(unsigned char *, void *))prf_hash_final;

		/* Init HMAC contexts.  */
		hash->HMACInit(hash, shared, sharedsize);

		/* Save contexts.  */
		memcpy(prfctx->ctx, hash->ctx, hash->ctxsize);
		memcpy(prfctx->ctx2, hash->ctx2, hash->ctxsize);
	}
	return prf;

cleanprfctx:
	free(prf->prfctx);
cleanprf:
	free(prf);
	return 0;
}

/* Deallocate the PRF pointed to by PRF.  */
void
prf_free(struct prf *prf)
{
	struct prf_hash_ctx *prfctx = prf->prfctx;

	if (prf->type == PRF_HMAC) {
		free(prfctx->ctx2);
		free(prfctx->ctx);
	}
	free(prf->prfctx);
	free(prf);
}