/*
 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL project
 * 2006.
 */
/* ====================================================================
 * Copyright (c) 2006 The OpenSSL Project.  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.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 OpenSSL PROJECT OR
 * ITS 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.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include "cryptlib.h"
#include <openssl/asn1t.h>
#include <openssl/x509.h>
#include <openssl/evp.h>
#include <openssl/dh.h>
#include <openssl/bn.h>
#include "evp_locl.h"

/* DH pkey context structure */

typedef struct {
    /* Parameter gen parameters */
    int prime_len;
    int generator;
    int use_dsa;
    /* Keygen callback info */
    int gentmp[2];
    /* message digest */
} DH_PKEY_CTX;

static int pkey_dh_init(EVP_PKEY_CTX *ctx)
{
    DH_PKEY_CTX *dctx;
    dctx = OPENSSL_malloc(sizeof(DH_PKEY_CTX));
    if (!dctx)
        return 0;
    dctx->prime_len = 1024;
    dctx->generator = 2;
    dctx->use_dsa = 0;

    ctx->data = dctx;
    ctx->keygen_info = dctx->gentmp;
    ctx->keygen_info_count = 2;

    return 1;
}

static int pkey_dh_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
{
    DH_PKEY_CTX *dctx, *sctx;
    if (!pkey_dh_init(dst))
        return 0;
    sctx = src->data;
    dctx = dst->data;
    dctx->prime_len = sctx->prime_len;
    dctx->generator = sctx->generator;
    dctx->use_dsa = sctx->use_dsa;
    return 1;
}

static void pkey_dh_cleanup(EVP_PKEY_CTX *ctx)
{
    DH_PKEY_CTX *dctx = ctx->data;
    if (dctx)
        OPENSSL_free(dctx);
}

static int pkey_dh_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
{
    DH_PKEY_CTX *dctx = ctx->data;
    switch (type) {
    case EVP_PKEY_CTRL_DH_PARAMGEN_PRIME_LEN:
        if (p1 < 256)
            return -2;
        dctx->prime_len = p1;
        return 1;

    case EVP_PKEY_CTRL_DH_PARAMGEN_GENERATOR:
        dctx->generator = p1;
        return 1;

    case EVP_PKEY_CTRL_PEER_KEY:
        /* Default behaviour is OK */
        return 1;

    default:
        return -2;

    }
}

static int pkey_dh_ctrl_str(EVP_PKEY_CTX *ctx,
                            const char *type, const char *value)
{
    if (!strcmp(type, "dh_paramgen_prime_len")) {
        int len;
        len = atoi(value);
        return EVP_PKEY_CTX_set_dh_paramgen_prime_len(ctx, len);
    }
    if (!strcmp(type, "dh_paramgen_generator")) {
        int len;
        len = atoi(value);
        return EVP_PKEY_CTX_set_dh_paramgen_generator(ctx, len);
    }
    return -2;
}

static int pkey_dh_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
    DH *dh = NULL;
    DH_PKEY_CTX *dctx = ctx->data;
    BN_GENCB *pcb, cb;
    int ret;
    if (ctx->pkey_gencb) {
        pcb = &cb;
        evp_pkey_set_cb_translate(pcb, ctx);
    } else
        pcb = NULL;
    dh = DH_new();
    if (!dh)
        return 0;
    ret = DH_generate_parameters_ex(dh,
                                    dctx->prime_len, dctx->generator, pcb);
    if (ret)
        EVP_PKEY_assign_DH(pkey, dh);
    else
        DH_free(dh);
    return ret;
}

static int pkey_dh_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
    DH *dh = NULL;
    if (ctx->pkey == NULL) {
        DHerr(DH_F_PKEY_DH_KEYGEN, DH_R_NO_PARAMETERS_SET);
        return 0;
    }
    dh = DH_new();
    if (!dh)
        return 0;
    EVP_PKEY_assign_DH(pkey, dh);
    /* Note: if error return, pkey is freed by parent routine */
    if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
        return 0;
    return DH_generate_key(pkey->pkey.dh);
}

static int pkey_dh_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
                          size_t *keylen)
{
    int ret;
    if (!ctx->pkey || !ctx->peerkey) {
        DHerr(DH_F_PKEY_DH_DERIVE, DH_R_KEYS_NOT_SET);
        return 0;
    }
    ret = DH_compute_key(key, ctx->peerkey->pkey.dh->pub_key,
                         ctx->pkey->pkey.dh);
    if (ret < 0)
        return ret;
    *keylen = ret;
    return 1;
}

const EVP_PKEY_METHOD dh_pkey_meth = {
    EVP_PKEY_DH,
    EVP_PKEY_FLAG_AUTOARGLEN,
    pkey_dh_init,
    pkey_dh_copy,
    pkey_dh_cleanup,

    0,
    pkey_dh_paramgen,

    0,
    pkey_dh_keygen,

    0,
    0,

    0,
    0,

    0, 0,

    0, 0, 0, 0,

    0, 0,

    0, 0,

    0,
    pkey_dh_derive,

    pkey_dh_ctrl,
    pkey_dh_ctrl_str
};
