/*
 * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (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
 */

#ifndef OPENSSL_NO_DEPRECATED_3_0
/* We need to use some deprecated APIs */
# define OPENSSL_SUPPRESS_DEPRECATED
#endif
#include <openssl/opensslconf.h>

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include "apps.h"
#include "progs.h"
#include <openssl/bio.h>
#include <openssl/err.h>
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/x509.h>
#include <openssl/pem.h>

#if !defined(OPENSSL_NO_DSA) && !defined(OPENSSL_NO_DEPRECATED_3_0)
# include <openssl/dsa.h>
#endif

#define DEFBITS 2048

#if !defined(OPENSSL_NO_DSA) && !defined(OPENSSL_NO_DEPRECATED_3_0)
static int dh_cb(int p, int n, BN_GENCB *cb);
#endif
static int gendh_cb(EVP_PKEY_CTX *ctx);

typedef enum OPTION_choice {
    OPT_ERR = -1, OPT_EOF = 0, OPT_HELP,
    OPT_INFORM, OPT_OUTFORM, OPT_IN, OPT_OUT,
    OPT_ENGINE, OPT_CHECK, OPT_TEXT, OPT_NOOUT,
    OPT_DSAPARAM, OPT_2, OPT_3, OPT_5,
    OPT_R_ENUM, OPT_PROV_ENUM
} OPTION_CHOICE;

const OPTIONS dhparam_options[] = {
    {OPT_HELP_STR, 1, '-', "Usage: %s [options] [numbits]\n"},

    OPT_SECTION("General"),
    {"help", OPT_HELP, '-', "Display this summary"},
    {"check", OPT_CHECK, '-', "Check the DH parameters"},
#ifndef OPENSSL_NO_DSA
    {"dsaparam", OPT_DSAPARAM, '-',
     "Read or generate DSA parameters, convert to DH"},
#endif
#ifndef OPENSSL_NO_ENGINE
    {"engine", OPT_ENGINE, 's', "Use engine e, possibly a hardware device"},
#endif

    OPT_SECTION("Input"),
    {"in", OPT_IN, '<', "Input file"},
    {"inform", OPT_INFORM, 'F', "Input format, DER or PEM"},

    OPT_SECTION("Output"),
    {"out", OPT_OUT, '>', "Output file"},
    {"outform", OPT_OUTFORM, 'F', "Output format, DER or PEM"},
    {"text", OPT_TEXT, '-', "Print a text form of the DH parameters"},
    {"noout", OPT_NOOUT, '-', "Don't output any DH parameters"},
    {"2", OPT_2, '-', "Generate parameters using 2 as the generator value"},
    {"3", OPT_3, '-', "Generate parameters using 3 as the generator value"},
    {"5", OPT_5, '-', "Generate parameters using 5 as the generator value"},

    OPT_R_OPTIONS,
    OPT_PROV_OPTIONS,

    OPT_PARAMETERS(),
    {"numbits", 0, 0, "Number of bits if generating parameters (optional)"},
    {NULL}
};

int dhparam_main(int argc, char **argv)
{
    BIO *in = NULL, *out = NULL;
    DH *dh = NULL, *alloc_dh = NULL;
    EVP_PKEY *pkey = NULL;
    EVP_PKEY_CTX *ctx = NULL;
    char *infile = NULL, *outfile = NULL, *prog;
    ENGINE *e = NULL;
#if !defined(OPENSSL_NO_DSA) && !defined(OPENSSL_NO_DEPRECATED_3_0)
    int dsaparam = 0;
#endif
    int i, text = 0, ret = 1, num = 0, g = 0;
    int informat = FORMAT_PEM, outformat = FORMAT_PEM, check = 0, noout = 0;
    OPTION_CHOICE o;

    prog = opt_init(argc, argv, dhparam_options);
    while ((o = opt_next()) != OPT_EOF) {
        switch (o) {
        case OPT_EOF:
        case OPT_ERR:
 opthelp:
            BIO_printf(bio_err, "%s: Use -help for summary.\n", prog);
            goto end;
        case OPT_HELP:
            opt_help(dhparam_options);
            ret = 0;
            goto end;
        case OPT_INFORM:
            if (!opt_format(opt_arg(), OPT_FMT_PEMDER, &informat))
                goto opthelp;
            break;
        case OPT_OUTFORM:
            if (!opt_format(opt_arg(), OPT_FMT_PEMDER, &outformat))
                goto opthelp;
            break;
        case OPT_IN:
            infile = opt_arg();
            break;
        case OPT_OUT:
            outfile = opt_arg();
            break;
        case OPT_ENGINE:
            e = setup_engine(opt_arg(), 0);
            break;
        case OPT_CHECK:
            check = 1;
            break;
        case OPT_TEXT:
            text = 1;
            break;
        case OPT_DSAPARAM:
#ifndef OPENSSL_NO_DSA
# ifdef OPENSSL_NO_DEPRECATED_3_0
            BIO_printf(bio_err, "The dsaparam option is deprecated.\n");
# else
            dsaparam = 1;
# endif
#endif
            break;
        case OPT_2:
            g = 2;
            break;
        case OPT_3:
            g = 3;
            break;
        case OPT_5:
            g = 5;
            break;
        case OPT_NOOUT:
            noout = 1;
            break;
        case OPT_R_CASES:
            if (!opt_rand(o))
                goto end;
            break;
        case OPT_PROV_CASES:
            if (!opt_provider(o))
                goto end;
            break;
        }
    }
    argc = opt_num_rest();
    argv = opt_rest();

    if (argv[0] != NULL && (!opt_int(argv[0], &num) || num <= 0))
        goto end;

    if (g && !num)
        num = DEFBITS;

#if !defined(OPENSSL_NO_DSA) && !defined(OPENSSL_NO_DEPRECATED_3_0)
    if (dsaparam && g) {
        BIO_printf(bio_err,
                   "Error, generator may not be chosen for DSA parameters\n");
        goto end;
    }
#endif

    out = bio_open_default(outfile, 'w', outformat);
    if (out == NULL)
        goto end;

    /* DH parameters */
    if (num && !g)
        g = 2;

    if (num) {


#if !defined(OPENSSL_NO_DSA) && !defined(OPENSSL_NO_DEPRECATED_3_0)
        if (dsaparam) {
            DSA *dsa = DSA_new();
            BN_GENCB *cb  = BN_GENCB_new();

            if (cb == NULL)
                goto end;

            BN_GENCB_set(cb, dh_cb, bio_err);

            BIO_printf(bio_err,
                       "Generating DSA parameters, %d bit long prime\n", num);
            if (dsa == NULL
                || !DSA_generate_parameters_ex(dsa, num, NULL, 0, NULL, NULL,
                                               cb)) {
                DSA_free(dsa);
                BN_GENCB_free(cb);
                BIO_printf(bio_err, "Error, unable to generate DSA parameters\n");
                goto end;
            }

            dh = alloc_dh = DSA_dup_DH(dsa);
            DSA_free(dsa);
            BN_GENCB_free(cb);
            if (dh == NULL)
                goto end;
        } else
#endif
        {
            ctx = EVP_PKEY_CTX_new_from_name(NULL, "DH", NULL);
            if (ctx == NULL) {
                BIO_printf(bio_err,
                           "Error, DH key generation context allocation failed\n");
                goto end;
            }
            EVP_PKEY_CTX_set_cb(ctx, gendh_cb);
            EVP_PKEY_CTX_set_app_data(ctx, bio_err);
            BIO_printf(bio_err,
                       "Generating DH parameters, %d bit long safe prime, generator %d\n",
                       num, g);
            BIO_printf(bio_err, "This is going to take a long time\n");
            if (!EVP_PKEY_paramgen_init(ctx)) {
                BIO_printf(bio_err,
                           "Error, unable to initialise DH param generation\n");
                goto end;
            }

            if (!EVP_PKEY_CTX_set_dh_paramgen_prime_len(ctx, num)) {
                BIO_printf(bio_err, "Error, unable to set DH prime length\n");
                goto end;
            }
            if (!EVP_PKEY_paramgen(ctx, &pkey)) {
                BIO_printf(bio_err, "Error, DH generation failed\n");
                goto end;
            }
            dh = EVP_PKEY_get0_DH(pkey);
        }
    } else {
        in = bio_open_default(infile, 'r', informat);
        if (in == NULL)
            goto end;

#if !defined(OPENSSL_NO_DSA) && !defined(OPENSSL_NO_DEPRECATED_3_0)
        if (dsaparam) {
            DSA *dsa;

            if (informat == FORMAT_ASN1)
                dsa = d2i_DSAparams_bio(in, NULL);
            else                /* informat == FORMAT_PEM */
                dsa = PEM_read_bio_DSAparams(in, NULL, NULL, NULL);

            if (dsa == NULL) {
                BIO_printf(bio_err, "Error, unable to load DSA parameters\n");
                goto end;
            }

            dh = alloc_dh = DSA_dup_DH(dsa);
            DSA_free(dsa);
            if (dh == NULL)
                goto end;
        } else
#endif
        {
            if (informat == FORMAT_ASN1) {
                /*
                 * We have no PEM header to determine what type of DH params it
                 * is. We'll just try both.
                 */
                dh = alloc_dh = ASN1_d2i_bio_of(DH, DH_new, d2i_DHparams, in, NULL);
                /* BIO_reset() returns 0 for success for file BIOs only!!! */
                if (dh == NULL && BIO_reset(in) == 0)
                    dh = alloc_dh = ASN1_d2i_bio_of(DH, DH_new, d2i_DHxparams, in, NULL);
            } else {
                /* informat == FORMAT_PEM */
                dh = alloc_dh = PEM_read_bio_DHparams(in, NULL, NULL, NULL);
            }

            if (dh == NULL) {
                BIO_printf(bio_err, "Error, unable to load DH parameters\n");
                goto end;
            }
        }
        /* dh != NULL */
    }

    if (text)
        EVP_PKEY_print_params(out, pkey, 4, NULL);

    if (check) {
        if (!EVP_PKEY_param_check(ctx) /* DH_check(dh, &i) */) {
            BIO_printf(bio_err, "Error, invalid parameters generated\n");
            goto end;
        }
        BIO_printf(bio_err, "DH parameters appear to be ok.\n");
        if (num != 0) {
            /*
             * We have generated parameters but DH_check() indicates they are
             * invalid! This should never happen!
             */
            BIO_printf(bio_err, "Error, invalid parameters generated\n");
            goto end;
        }
    }

    if (!noout) {
        const BIGNUM *q;
        DH_get0_pqg(dh, NULL, &q, NULL);
        if (outformat == FORMAT_ASN1) {
            if (q != NULL)
                i = ASN1_i2d_bio_of(DH, i2d_DHxparams, out, dh);
            else
                i = ASN1_i2d_bio_of(DH, i2d_DHparams, out, dh);
        } else if (q != NULL) {
            i = PEM_write_bio_DHxparams(out, dh);
        } else {
            i = PEM_write_bio_DHparams(out, dh);
        }
        if (!i) {
            BIO_printf(bio_err, "Error, unable to write DH parameters\n");
            goto end;
        }
    }
    ret = 0;
 end:
    if (ret != 0)
        ERR_print_errors(bio_err);
    DH_free(alloc_dh);
    BIO_free(in);
    BIO_free_all(out);
    EVP_PKEY_free(pkey);
    EVP_PKEY_CTX_free(ctx);
    release_engine(e);
    return ret;
}

static int common_dh_cb(int p, BIO *b)
{
    static const char symbols[] = ".+*\n";
    char c = (p >= 0 && (size_t)p < sizeof(symbols) - 1) ? symbols[p] : '?';

    BIO_write(b, &c, 1);
    (void)BIO_flush(b);
    return 1;
}

#if !defined(OPENSSL_NO_DSA) && !defined(OPENSSL_NO_DEPRECATED_3_0)
static int dh_cb(int p, int n, BN_GENCB *cb)
{
    return common_dh_cb(p, BN_GENCB_get_arg(cb));
}
#endif

static int gendh_cb(EVP_PKEY_CTX *ctx)
{
    return common_dh_cb(EVP_PKEY_CTX_get_keygen_info(ctx, 0),
                        EVP_PKEY_CTX_get_app_data(ctx));
}