/*

 * Copyright 1995-2020 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 <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/dsa.h>

#include <openssl/x509.h>

#include <openssl/pem.h>

static int dsa_cb(int p, int n, BN_GENCB *cb);

typedef enum OPTION_choice {

    OPT_ERR = -1, OPT_EOF = 0, OPT_HELP,

    OPT_INFORM, OPT_OUTFORM, OPT_IN, OPT_OUT, OPT_TEXT, OPT_C,

    OPT_NOOUT, OPT_GENKEY, OPT_ENGINE, OPT_R_ENUM

} OPTION_CHOICE;

const OPTIONS dsaparam_options[] = {

    {"help", OPT_HELP, '-', "Display this summary"},

    {"inform", OPT_INFORM, 'F', "Input format - DER or PEM"},

    {"in", OPT_IN, '<', "Input file"},

    {"outform", OPT_OUTFORM, 'F', "Output format - DER or PEM"},

    {"out", OPT_OUT, '>', "Output file"},

    {"text", OPT_TEXT, '-', "Print as text"},

    {"C", OPT_C, '-', "Output C code"},

    {"noout", OPT_NOOUT, '-', "No output"},

    {"genkey", OPT_GENKEY, '-', "Generate a DSA key"},

    OPT_R_OPTIONS,

#ifndef OPENSSL_NO_ENGINE

    {"engine", OPT_ENGINE, 's', "Use engine e, possibly a hardware device"},

#endif

    {NULL}

};

int dsaparam_main(int argc, char **argv)

{

    ENGINE *e = NULL;

    DSA *dsa = NULL;

    BIO *in = NULL, *out = NULL;

    BN_GENCB *cb = NULL;

    int numbits = -1, num = 0, genkey = 0;

    int informat = FORMAT_PEM, outformat = FORMAT_PEM, noout = 0, C = 0;

    int ret = 1, i, text = 0, private = 0;

    char *infile = NULL, *outfile = NULL, *prog;

    OPTION_CHOICE o;

    prog = opt_init(argc, argv, dsaparam_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(dsaparam_options);

            ret = 0;

            goto end;

        case OPT_INFORM:

            if (!opt_format(opt_arg(), OPT_FMT_PEMDER, &informat))

                goto opthelp;

            break;

        case OPT_IN:

            infile = opt_arg();

            break;

        case OPT_OUTFORM:

            if (!opt_format(opt_arg(), OPT_FMT_PEMDER, &outformat))

                goto opthelp;

            break;

        case OPT_OUT:

            outfile = opt_arg();

            break;

        case OPT_ENGINE:

            e = setup_engine(opt_arg(), 0);

            break;

        case OPT_TEXT:

            text = 1;

            break;

        case OPT_C:

            C = 1;

            break;

        case OPT_GENKEY:

            genkey = 1;

            break;

        case OPT_R_CASES:

            if (!opt_rand(o))

                goto end;

            break;

        case OPT_NOOUT:

            noout = 1;

            break;

        }

    }

    argc = opt_num_rest();

    argv = opt_rest();

    if (argc == 1) {

        if (!opt_int(argv[0], &num) || num < 0)

            goto end;

        /* generate a key */

        numbits = num;

    }

    private = genkey ? 1 : 0;

    in = bio_open_default(infile, 'r', informat);

    if (in == NULL)

        goto end;

    out = bio_open_owner(outfile, outformat, private);

    if (out == NULL)

        goto end;

    if (numbits > 0) {

        if (numbits > OPENSSL_DSA_MAX_MODULUS_BITS)

            BIO_printf(bio_err,

                       "Warning: It is not recommended to use more than %d bit for DSA keys.\n"

                       "         Your key size is %d! Larger key size may behave not as expected.\n",

                       OPENSSL_DSA_MAX_MODULUS_BITS, numbits);

        cb = BN_GENCB_new();

        if (cb == NULL) {

            BIO_printf(bio_err, "Error allocating BN_GENCB object\n");

            goto end;

        }

        BN_GENCB_set(cb, dsa_cb, bio_err);

        dsa = DSA_new();

        if (dsa == NULL) {

            BIO_printf(bio_err, "Error allocating DSA object\n");

            goto end;

        }

        BIO_printf(bio_err, "Generating DSA parameters, %d bit long prime\n",

                   num);

        BIO_printf(bio_err, "This could take some time\n");

        if (!DSA_generate_parameters_ex(dsa, num, NULL, 0, NULL, NULL, cb)) {

            ERR_print_errors(bio_err);

            BIO_printf(bio_err, "Error, DSA key generation failed\n");

            goto end;

        }

    } else if (informat == FORMAT_ASN1) {

        dsa = d2i_DSAparams_bio(in, NULL);

    } else {

        dsa = PEM_read_bio_DSAparams(in, NULL, NULL, NULL);

    }

    if (dsa == NULL) {

        BIO_printf(bio_err, "unable to load DSA parameters\n");

        ERR_print_errors(bio_err);

        goto end;

    }

    if (text) {

        DSAparams_print(out, dsa);

    }

    if (C) {

        const BIGNUM *p = NULL, *q = NULL, *g = NULL;

        unsigned char *data;

        int len, bits_p;

        DSA_get0_pqg(dsa, &p, &q, &g);

        len = BN_num_bytes(p);

        bits_p = BN_num_bits(p);

        data = app_malloc(len + 20, "BN space");

        BIO_printf(bio_out, "static DSA *get_dsa%d(void)\n{\n", bits_p);

        print_bignum_var(bio_out, p, "dsap", bits_p, data);

        print_bignum_var(bio_out, q, "dsaq", bits_p, data);

        print_bignum_var(bio_out, g, "dsag", bits_p, data);

        BIO_printf(bio_out, "    DSA *dsa = DSA_new();\n"

                            "    BIGNUM *p, *q, *g;\n"

                            "\n");

        BIO_printf(bio_out, "    if (dsa == NULL)\n"

                            "        return NULL;\n");

        BIO_printf(bio_out, "    if (!DSA_set0_pqg(dsa, p = BN_bin2bn(dsap_%d, sizeof(dsap_%d), NULL),\n",

                   bits_p, bits_p);

        BIO_printf(bio_out, "                           q = BN_bin2bn(dsaq_%d, sizeof(dsaq_%d), NULL),\n",

                   bits_p, bits_p);

        BIO_printf(bio_out, "                           g = BN_bin2bn(dsag_%d, sizeof(dsag_%d), NULL))) {\n",

                   bits_p, bits_p);

        BIO_printf(bio_out, "        DSA_free(dsa);\n"

                            "        BN_free(p);\n"

                            "        BN_free(q);\n"

                            "        BN_free(g);\n"

                            "        return NULL;\n"

                            "    }\n"

                            "    return dsa;\n}\n");

        OPENSSL_free(data);

    }

    if (outformat == FORMAT_ASN1 && genkey)

        noout = 1;

    if (!noout) {

        if (outformat == FORMAT_ASN1)

            i = i2d_DSAparams_bio(out, dsa);

        else

            i = PEM_write_bio_DSAparams(out, dsa);

        if (!i) {

            BIO_printf(bio_err, "unable to write DSA parameters\n");

            ERR_print_errors(bio_err);

            goto end;

        }

    }

    if (genkey) {

        DSA *dsakey;

        if ((dsakey = DSAparams_dup(dsa)) == NULL)

            goto end;

        if (!DSA_generate_key(dsakey)) {

            ERR_print_errors(bio_err);

            DSA_free(dsakey);

            goto end;

        }

        assert(private);

        if (outformat == FORMAT_ASN1)

            i = i2d_DSAPrivateKey_bio(out, dsakey);

        else

            i = PEM_write_bio_DSAPrivateKey(out, dsakey, NULL, NULL, 0, NULL,

                                            NULL);

        DSA_free(dsakey);

    }

    ret = 0;

 end:

    BN_GENCB_free(cb);

    BIO_free(in);

    BIO_free_all(out);

    DSA_free(dsa);

    release_engine(e);

    return ret;

}

static int dsa_cb(int p, int n, BN_GENCB *cb)

{

    static const char symbols[] = ".+*\n";

    char c = (p >= 0 && (size_t)p < sizeof(symbols) - 1) ? symbols[p] : '?';

    BIO_write(BN_GENCB_get_arg(cb), &c, 1);

    (void)BIO_flush(BN_GENCB_get_arg(cb));

    return 1;

}