/*
 * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/asn1t.h>
#include <openssl/x509.h>
#include <openssl/evp.h>
#include "dh_locl.h"
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/objects.h>
#include "internal/evp_int.h"

/* DH pkey context structure */

typedef struct {
    /* Parameter gen parameters */
    int prime_len;
    int generator;
    int use_dsa;
    int subprime_len;
    /* message digest used for parameter generation */
    const EVP_MD *md;
    int rfc5114_param;
    /* Keygen callback info */
    int gentmp[2];
    /* KDF (if any) to use for DH */
    char kdf_type;
    /* OID to use for KDF */
    ASN1_OBJECT *kdf_oid;
    /* Message digest to use for key derivation */
    const EVP_MD *kdf_md;
    /* User key material */
    unsigned char *kdf_ukm;
    size_t kdf_ukmlen;
    /* KDF output length */
    size_t kdf_outlen;
} DH_PKEY_CTX;

static int pkey_dh_init(EVP_PKEY_CTX *ctx)
{
    DH_PKEY_CTX *dctx;

    dctx = OPENSSL_zalloc(sizeof(*dctx));
    if (dctx == NULL)
        return 0;
    dctx->prime_len = 1024;
    dctx->subprime_len = -1;
    dctx->generator = 2;
    dctx->kdf_type = EVP_PKEY_DH_KDF_NONE;

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

    return 1;
}

static void pkey_dh_cleanup(EVP_PKEY_CTX *ctx)
{
    DH_PKEY_CTX *dctx = ctx->data;
    if (dctx != NULL) {
        OPENSSL_free(dctx->kdf_ukm);
        ASN1_OBJECT_free(dctx->kdf_oid);
        OPENSSL_free(dctx);
    }
}


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->subprime_len = sctx->subprime_len;
    dctx->generator = sctx->generator;
    dctx->use_dsa = sctx->use_dsa;
    dctx->md = sctx->md;
    dctx->rfc5114_param = sctx->rfc5114_param;

    dctx->kdf_type = sctx->kdf_type;
    dctx->kdf_oid = OBJ_dup(sctx->kdf_oid);
    if (dctx->kdf_oid == NULL)
        return 0;
    dctx->kdf_md = sctx->kdf_md;
    if (sctx->kdf_ukm != NULL) {
        dctx->kdf_ukm = OPENSSL_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
        if (dctx->kdf_ukm == NULL)
          return 0;
        dctx->kdf_ukmlen = sctx->kdf_ukmlen;
    }
    dctx->kdf_outlen = sctx->kdf_outlen;
    return 1;
}

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_SUBPRIME_LEN:
        if (dctx->use_dsa == 0)
            return -2;
        dctx->subprime_len = p1;
        return 1;

    case EVP_PKEY_CTRL_DH_PARAMGEN_GENERATOR:
        if (dctx->use_dsa)
            return -2;
        dctx->generator = p1;
        return 1;

    case EVP_PKEY_CTRL_DH_PARAMGEN_TYPE:
#ifdef OPENSSL_NO_DSA
        if (p1 != 0)
            return -2;
#else
        if (p1 < 0 || p1 > 2)
            return -2;
#endif
        dctx->use_dsa = p1;
        return 1;

    case EVP_PKEY_CTRL_DH_RFC5114:
        if (p1 < 1 || p1 > 3)
            return -2;
        dctx->rfc5114_param = p1;
        return 1;

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

    case EVP_PKEY_CTRL_DH_KDF_TYPE:
        if (p1 == -2)
            return dctx->kdf_type;
#ifdef OPENSSL_NO_CMS
        if (p1 != EVP_PKEY_DH_KDF_NONE)
#else
        if (p1 != EVP_PKEY_DH_KDF_NONE && p1 != EVP_PKEY_DH_KDF_X9_42)
#endif
            return -2;
        dctx->kdf_type = p1;
        return 1;

    case EVP_PKEY_CTRL_DH_KDF_MD:
        dctx->kdf_md = p2;
        return 1;

    case EVP_PKEY_CTRL_GET_DH_KDF_MD:
        *(const EVP_MD **)p2 = dctx->kdf_md;
        return 1;

    case EVP_PKEY_CTRL_DH_KDF_OUTLEN:
        if (p1 <= 0)
            return -2;
        dctx->kdf_outlen = (size_t)p1;
        return 1;

    case EVP_PKEY_CTRL_GET_DH_KDF_OUTLEN:
        *(int *)p2 = dctx->kdf_outlen;
        return 1;

    case EVP_PKEY_CTRL_DH_KDF_UKM:
        OPENSSL_free(dctx->kdf_ukm);
        dctx->kdf_ukm = p2;
        if (p2)
            dctx->kdf_ukmlen = p1;
        else
            dctx->kdf_ukmlen = 0;
        return 1;

    case EVP_PKEY_CTRL_GET_DH_KDF_UKM:
        *(unsigned char **)p2 = dctx->kdf_ukm;
        return dctx->kdf_ukmlen;

    case EVP_PKEY_CTRL_DH_KDF_OID:
        ASN1_OBJECT_free(dctx->kdf_oid);
        dctx->kdf_oid = p2;
        return 1;

    case EVP_PKEY_CTRL_GET_DH_KDF_OID:
        *(ASN1_OBJECT **)p2 = dctx->kdf_oid;
        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") == 0) {
        int len;
        len = atoi(value);
        return EVP_PKEY_CTX_set_dh_paramgen_prime_len(ctx, len);
    }
    if (strcmp(type, "dh_rfc5114") == 0) {
        DH_PKEY_CTX *dctx = ctx->data;
        int len;
        len = atoi(value);
        if (len < 0 || len > 3)
            return -2;
        dctx->rfc5114_param = len;
        return 1;
    }
    if (strcmp(type, "dh_paramgen_generator") == 0) {
        int len;
        len = atoi(value);
        return EVP_PKEY_CTX_set_dh_paramgen_generator(ctx, len);
    }
    if (strcmp(type, "dh_paramgen_subprime_len") == 0) {
        int len;
        len = atoi(value);
        return EVP_PKEY_CTX_set_dh_paramgen_subprime_len(ctx, len);
    }
    if (strcmp(type, "dh_paramgen_type") == 0) {
        int typ;
        typ = atoi(value);
        return EVP_PKEY_CTX_set_dh_paramgen_type(ctx, typ);
    }
    return -2;
}

#ifndef OPENSSL_NO_DSA

extern int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
                                const EVP_MD *evpmd,
                                const unsigned char *seed_in, size_t seed_len,
                                unsigned char *seed_out, int *counter_ret,
                                unsigned long *h_ret, BN_GENCB *cb);

extern int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
                                 const EVP_MD *evpmd,
                                 const unsigned char *seed_in,
                                 size_t seed_len, int idx,
                                 unsigned char *seed_out, int *counter_ret,
                                 unsigned long *h_ret, BN_GENCB *cb);

static DSA *dsa_dh_generate(DH_PKEY_CTX *dctx, BN_GENCB *pcb)
{
    DSA *ret;
    int rv = 0;
    int prime_len = dctx->prime_len;
    int subprime_len = dctx->subprime_len;
    const EVP_MD *md = dctx->md;
    if (dctx->use_dsa > 2)
        return NULL;
    ret = DSA_new();
    if (ret == NULL)
        return NULL;
    if (subprime_len == -1) {
        if (prime_len >= 2048)
            subprime_len = 256;
        else
            subprime_len = 160;
    }
    if (md == NULL) {
        if (prime_len >= 2048)
            md = EVP_sha256();
        else
            md = EVP_sha1();
    }
    if (dctx->use_dsa == 1)
        rv = dsa_builtin_paramgen(ret, prime_len, subprime_len, md,
                                  NULL, 0, NULL, NULL, NULL, pcb);
    else if (dctx->use_dsa == 2)
        rv = dsa_builtin_paramgen2(ret, prime_len, subprime_len, md,
                                   NULL, 0, -1, NULL, NULL, NULL, pcb);
    if (rv <= 0) {
        DSA_free(ret);
        return NULL;
    }
    return ret;
}

#endif

static int pkey_dh_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
    DH *dh = NULL;
    DH_PKEY_CTX *dctx = ctx->data;
    BN_GENCB *pcb;
    int ret;
    if (dctx->rfc5114_param) {
        switch (dctx->rfc5114_param) {
        case 1:
            dh = DH_get_1024_160();
            break;

        case 2:
            dh = DH_get_2048_224();
            break;

        case 3:
            dh = DH_get_2048_256();
            break;

        default:
            return -2;
        }
        EVP_PKEY_assign(pkey, EVP_PKEY_DHX, dh);
        return 1;
    }

    if (ctx->pkey_gencb) {
        pcb = BN_GENCB_new();
        if (pcb == NULL)
            return 0;
        evp_pkey_set_cb_translate(pcb, ctx);
    } else
        pcb = NULL;
#ifndef OPENSSL_NO_DSA
    if (dctx->use_dsa) {
        DSA *dsa_dh;
        dsa_dh = dsa_dh_generate(dctx, pcb);
        BN_GENCB_free(pcb);
        if (dsa_dh == NULL)
            return 0;
        dh = DSA_dup_DH(dsa_dh);
        DSA_free(dsa_dh);
        if (!dh)
            return 0;
        EVP_PKEY_assign(pkey, EVP_PKEY_DHX, dh);
        return 1;
    }
#endif
    dh = DH_new();
    if (dh == NULL) {
        BN_GENCB_free(pcb);
        return 0;
    }
    ret = DH_generate_parameters_ex(dh,
                                    dctx->prime_len, dctx->generator, pcb);
    BN_GENCB_free(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 == NULL)
        return 0;
    EVP_PKEY_assign(pkey, ctx->pmeth->pkey_id, 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;
    DH *dh;
    DH_PKEY_CTX *dctx = ctx->data;
    BIGNUM *dhpub;
    if (!ctx->pkey || !ctx->peerkey) {
        DHerr(DH_F_PKEY_DH_DERIVE, DH_R_KEYS_NOT_SET);
        return 0;
    }
    dh = ctx->pkey->pkey.dh;
    dhpub = ctx->peerkey->pkey.dh->pub_key;
    if (dctx->kdf_type == EVP_PKEY_DH_KDF_NONE) {
        if (key == NULL) {
            *keylen = DH_size(dh);
            return 1;
        }
        ret = DH_compute_key(key, dhpub, dh);
        if (ret < 0)
            return ret;
        *keylen = ret;
        return 1;
    }
#ifndef OPENSSL_NO_CMS
    else if (dctx->kdf_type == EVP_PKEY_DH_KDF_X9_42) {

        unsigned char *Z = NULL;
        size_t Zlen = 0;
        if (!dctx->kdf_outlen || !dctx->kdf_oid)
            return 0;
        if (key == NULL) {
            *keylen = dctx->kdf_outlen;
            return 1;
        }
        if (*keylen != dctx->kdf_outlen)
            return 0;
        ret = 0;
        Zlen = DH_size(dh);
        Z = OPENSSL_malloc(Zlen);
        if (Z == NULL) {
            goto err;
        }
        if (DH_compute_key_padded(Z, dhpub, dh) <= 0)
            goto err;
        if (!DH_KDF_X9_42(key, *keylen, Z, Zlen, dctx->kdf_oid,
                          dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md))
            goto err;
        *keylen = dctx->kdf_outlen;
        ret = 1;
 err:
        OPENSSL_clear_free(Z, Zlen);
        return ret;
    }
#endif
    return 0;
}

const EVP_PKEY_METHOD dh_pkey_meth = {
    EVP_PKEY_DH,
    0,
    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
};

const EVP_PKEY_METHOD dhx_pkey_meth = {
    EVP_PKEY_DHX,
    0,
    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
};