xrdp/common/ssl_calls.c

/**
 * xrdp: A Remote Desktop Protocol server.
 *
 * Copyright (C) Jay Sorg 2004-2014
 * Copyright (C) Idan Freiberg 2013-2014
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * ssl calls
 */

#if defined(HAVE_CONFIG_H)
#include <config_ac.h>
#endif

#include <stdlib.h> /* needed for openssl headers */
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/rc4.h>
#include <openssl/md5.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/dh.h>
#include <openssl/crypto.h>

#include "os_calls.h"
#include "string_calls.h"
#include "arch.h"
#include "ssl_calls.h"
#include "trans.h"
#include "log.h"

#define SSL_WANT_READ_WRITE_TIMEOUT 100

/*
 * Globals used by openssl 3 and later */
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
static EVP_MD *g_md_md5;    /* MD5 message digest */
static EVP_MD *g_md_sha1;   /* SHA1 message digest */
static EVP_CIPHER *g_cipher_des_ede3_cbc; /* DES3 CBC cipher */
static EVP_MAC *g_mac_hmac; /* HMAC MAC */
#endif

/* definition of ssl_tls */
struct ssl_tls
{
    SSL *ssl; /* SSL * */
    SSL_CTX *ctx; /* SSL_CTX * */
    char *cert;
    char *key;
    struct trans *trans;
    tintptr rwo; /* wait obj */
    int error_logged; /* Error has already been logged */
};

#if OPENSSL_VERSION_NUMBER < 0x10100000L
static inline HMAC_CTX *
HMAC_CTX_new(void)
{
    HMAC_CTX *hmac_ctx = g_new(HMAC_CTX, 1);
    HMAC_CTX_init(hmac_ctx);
    return hmac_ctx;
}

static inline void
HMAC_CTX_free(HMAC_CTX *hmac_ctx)
{
    HMAC_CTX_cleanup(hmac_ctx);
    g_free(hmac_ctx);
}

static inline void
RSA_get0_key(const RSA *key, const BIGNUM **n, const BIGNUM **e,
             const BIGNUM **d)
{
    *n = key->n;
    *d = key->d;
}

static inline int
DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g)
{
    /* If the fields p and g in d are NULL, the corresponding input
     * parameters MUST be non-NULL.  q may remain NULL.
     */
    if ((dh->p == NULL && p == NULL)
            || (dh->g == NULL && g == NULL))
    {
        return 0;
    }

    if (p != NULL)
    {
        BN_free(dh->p);
        dh->p = p;
    }
    if (q != NULL)
    {
        BN_free(dh->q);
        dh->q = q;
    }
    if (g != NULL)
    {
        BN_free(dh->g);
        dh->g = g;
    }

    if (q != NULL)
    {
        dh->length = BN_num_bits(q);
    }

    return 1;
}
#endif /* OPENSSL_VERSION_NUMBER >= 0x10100000L */



/*****************************************************************************/
static void
dump_error_stack(const char *prefix)
{
    /* Dump the error stack from the SSL library */
    unsigned long code;
    char buff[256];
    while ((code = ERR_get_error()) != 0L)
    {
        ERR_error_string_n(code, buff, sizeof(buff));
        LOG(LOG_LEVEL_ERROR, "%s: %s", prefix, buff);
    }
}

/*****************************************************************************/
/* As above, but used for TLS connection errors where only the first
   error is logged */
static void
dump_ssl_error_stack(struct ssl_tls *self)
{
    if (!self->error_logged)
    {
        dump_error_stack("SSL");
        self->error_logged = 1;
    }
}

/*****************************************************************************/
int
ssl_init(void)
{
    SSL_load_error_strings();
    SSL_library_init();

    return 0;
}

/*****************************************************************************/
int
ssl_finish(void)
{
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
    /* De-allocate any allocated globals
     * For OpenSSL 3, these can all safely be passed a NULL pointer */
    EVP_MD_free(g_md_md5);
    EVP_MD_free(g_md_sha1);
    EVP_CIPHER_free(g_cipher_des_ede3_cbc);
    EVP_MAC_free(g_mac_hmac);
#endif
    return 0;
}

/* rc4 stuff
 *
 * For OpenSSL 3.0, the rc4 encryption algorithm is only provided by the
 * legacy provider (see crypto(7)). Since RC4 is so simple, we can implement
 * it directly rather than having to load the legacy provider.  This will
 * avoids problems if running on a system where openssl has been built
 * without the legacy provider */

#if OPENSSL_VERSION_NUMBER >= 0x30000000L
struct rc4_data
{
    /* See https://en.wikipedia.org/wiki/RC4 */
    unsigned char S[256];
    int i;
    int j;
};
#endif

/*****************************************************************************/
void *
ssl_rc4_info_create(void)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    return g_malloc(sizeof(RC4_KEY), 1);
#else
    return g_malloc(sizeof(struct rc4_data), 1);
#endif
}

/*****************************************************************************/
void
ssl_rc4_info_delete(void *rc4_info)
{
    g_free(rc4_info);
}

/*****************************************************************************/
void
ssl_rc4_set_key(void *rc4_info, const char *key, int len)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    RC4_set_key((RC4_KEY *)rc4_info, len, (tui8 *)key);
#else
    unsigned char *S = ((struct rc4_data *)rc4_info)->S;
    int i;
    int j = 0;
    unsigned char t;
    for (i = 0 ; i < 256; ++i)
    {
        S[i] = i;
    }
    for (i = 0 ; i < 256; ++i)
    {
        j = (j + S[i] + key[i % len]) & 0xff;
        t = S[i];
        S[i] = S[j];
        S[j] = t;
    }
    ((struct rc4_data *)rc4_info)->i = 0;
    ((struct rc4_data *)rc4_info)->j = 0;
#endif
}

/*****************************************************************************/
void
ssl_rc4_crypt(void *rc4_info, char *data, int len)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    RC4((RC4_KEY *)rc4_info, len, (tui8 *)data, (tui8 *)data);
#else
    unsigned char *S = ((struct rc4_data *)rc4_info)->S;
    int i = ((struct rc4_data *)rc4_info)->i;
    int j = ((struct rc4_data *)rc4_info)->j;
    unsigned char *p = (unsigned char *)data;
    unsigned char t;
    unsigned char k;

    /*
     * Do some loop-unrolling for performance. Here are the steps
     * for each byte */
#define RC4_ROUND \
    i = (i + 1) & 0xff; \
    j = (j + S[i]) & 0xff; \
    t = S[i]; \
    S[i] = S[j]; \
    S[j] = t; \
    k = S[(S[i] + S[j]) & 0xff]; \
    *p++ ^= k

    while (len >= 8)
    {
        RC4_ROUND;
        RC4_ROUND;
        RC4_ROUND;
        RC4_ROUND;
        RC4_ROUND;
        RC4_ROUND;
        RC4_ROUND;
        RC4_ROUND;
        len -= 8;
    }
    while (len-- > 0)
    {
        RC4_ROUND;
    }

    ((struct rc4_data *)rc4_info)->i = i;
    ((struct rc4_data *)rc4_info)->j = j;
#endif
}

/* sha1 stuff */

/*****************************************************************************/
void *
ssl_sha1_info_create(void)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    return g_malloc(sizeof(SHA_CTX), 1);
#else
    /*
     * If we can't get the digest loaded, there's a problem with the
     * library providers, so there's no point in us returning anything useful.
     * If we do load the digest, it's used later */
    if (g_md_sha1 == NULL)
    {
        if ((g_md_sha1 = EVP_MD_fetch(NULL, "sha1", NULL)) == NULL)
        {
            dump_error_stack("sha1");
            return NULL;
        }
    }

    return (void *)EVP_MD_CTX_new();
#endif
}

/*****************************************************************************/
void
ssl_sha1_info_delete(void *sha1_info)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    g_free(sha1_info);
#else
    EVP_MD_CTX_free((EVP_MD_CTX *)sha1_info);
#endif
}

/*****************************************************************************/
void
ssl_sha1_clear(void *sha1_info)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    SHA1_Init((SHA_CTX *)sha1_info);
#else
    if (sha1_info != NULL)
    {
        EVP_DigestInit_ex((EVP_MD_CTX *)sha1_info, g_md_sha1, NULL);
    }
#endif
}

/*****************************************************************************/
void
ssl_sha1_transform(void *sha1_info, const char *data, int len)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    SHA1_Update((SHA_CTX *)sha1_info, data, len);
#else
    if (sha1_info != NULL)
    {
        EVP_DigestUpdate((EVP_MD_CTX *)sha1_info, data, len);
    }
#endif
}

/*****************************************************************************/
void
ssl_sha1_complete(void *sha1_info, char *data)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    SHA1_Final((tui8 *)data, (SHA_CTX *)sha1_info);
#else
    if (sha1_info != NULL)
    {
        EVP_DigestFinal_ex((EVP_MD_CTX *)sha1_info, (unsigned char *)data,
                           NULL);
    }
#endif
}

/* md5 stuff */

/*****************************************************************************/
void *
ssl_md5_info_create(void)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    return g_malloc(sizeof(MD5_CTX), 1);
#else
    /*
     * If we can't get the digest loaded, there's a problem with the
     * library providers, so there's no point in us returning anything useful.
     * If we do load the digest, it's used later */
    if (g_md_md5 == NULL)
    {
        if ((g_md_md5 = EVP_MD_fetch(NULL, "md5", NULL)) == NULL)
        {
            dump_error_stack("md5");
            return NULL;
        }
    }

    return (void *)EVP_MD_CTX_new();
#endif
}

/*****************************************************************************/
void
ssl_md5_info_delete(void *md5_info)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    g_free(md5_info);
#else
    EVP_MD_CTX_free((EVP_MD_CTX *)md5_info);
#endif
}

/*****************************************************************************/
void
ssl_md5_clear(void *md5_info)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    MD5_Init((MD5_CTX *)md5_info);
#else
    if (md5_info != NULL)
    {
        EVP_DigestInit_ex((EVP_MD_CTX *)md5_info, g_md_md5, NULL);
    }
#endif
}

/*****************************************************************************/
void
ssl_md5_transform(void *md5_info, const char *data, int len)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    MD5_Update((MD5_CTX *)md5_info, data, len);
#else
    if (md5_info != NULL)
    {
        EVP_DigestUpdate((EVP_MD_CTX *)md5_info, data, len);
    }
#endif
}

/*****************************************************************************/
void
ssl_md5_complete(void *md5_info, char *data)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    MD5_Final((tui8 *)data, (MD5_CTX *)md5_info);
#else
    if (md5_info != NULL)
    {
        EVP_DigestFinal_ex((EVP_MD_CTX *)md5_info, (unsigned char *)data, NULL);
    }
#endif
}

/* FIPS stuff */

/*****************************************************************************/
void *
ssl_des3_encrypt_info_create(const char *key, const char *ivec)
{
    EVP_CIPHER_CTX *des3_ctx;
    const tui8 *lkey;
    const tui8 *livec;

#if OPENSSL_VERSION_NUMBER >= 0x30000000L
    /*
     * For these versions of OpenSSL, there are no long-term guarantees the
     * DES3 cipher will be available. We'll try to load it here so we
     * can log any errors */
    if (g_cipher_des_ede3_cbc == NULL)
    {
        g_cipher_des_ede3_cbc = EVP_CIPHER_fetch(NULL, "des-ede3-cbc", NULL);
        if (g_cipher_des_ede3_cbc == NULL)
        {
            dump_error_stack("DES-EDE3-CBC");
            return NULL;
        }
    }
#endif

    des3_ctx = EVP_CIPHER_CTX_new();
    lkey = (const tui8 *) key;
    livec = (const tui8 *) ivec;
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    EVP_EncryptInit_ex(des3_ctx, EVP_des_ede3_cbc(), NULL, lkey, livec);
#else
    EVP_EncryptInit_ex(des3_ctx, g_cipher_des_ede3_cbc, NULL, lkey, livec);
#endif
    EVP_CIPHER_CTX_set_padding(des3_ctx, 0);
    return des3_ctx;
}

/*****************************************************************************/
void *
ssl_des3_decrypt_info_create(const char *key, const char *ivec)
{
    EVP_CIPHER_CTX *des3_ctx;
    const tui8 *lkey;
    const tui8 *livec;

#if OPENSSL_VERSION_NUMBER >= 0x30000000L
    /*
     * For these versions of OpenSSL, there are no long-term guarantees the
     * DES3 cipher will be available. We'll try to load it here so we
     * can log any errors */
    if (g_cipher_des_ede3_cbc == NULL)
    {
        g_cipher_des_ede3_cbc = EVP_CIPHER_fetch(NULL, "des-ede3-cbc", NULL);
        if (g_cipher_des_ede3_cbc == NULL)
        {
            dump_error_stack("DES-EDE3-CBC");
            return NULL;
        }
    }
#endif

    des3_ctx = EVP_CIPHER_CTX_new();
    lkey = (const tui8 *) key;
    livec = (const tui8 *) ivec;
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    EVP_DecryptInit_ex(des3_ctx, EVP_des_ede3_cbc(), NULL, lkey, livec);
#else
    EVP_DecryptInit_ex(des3_ctx, g_cipher_des_ede3_cbc, NULL, lkey, livec);
#endif
    EVP_CIPHER_CTX_set_padding(des3_ctx, 0);
    return des3_ctx;
}

/*****************************************************************************/
void
ssl_des3_info_delete(void *des3)
{
    EVP_CIPHER_CTX *des3_ctx;

    des3_ctx = (EVP_CIPHER_CTX *) des3;
    if (des3_ctx != 0)
    {
        EVP_CIPHER_CTX_free(des3_ctx);
    }
}

/*****************************************************************************/
int
ssl_des3_encrypt(void *des3, int length, const char *in_data, char *out_data)
{
    EVP_CIPHER_CTX *des3_ctx;
    int len;
    const tui8 *lin_data;
    tui8 *lout_data;

    des3_ctx = (EVP_CIPHER_CTX *) des3;
    if (des3_ctx != NULL)
    {
        lin_data = (const tui8 *) in_data;
        lout_data = (tui8 *) out_data;
        len = 0;
        EVP_EncryptUpdate(des3_ctx, lout_data, &len, lin_data, length);
    }
    return 0;
}

/*****************************************************************************/
int
ssl_des3_decrypt(void *des3, int length, const char *in_data, char *out_data)
{
    EVP_CIPHER_CTX *des3_ctx;
    int len;
    const tui8 *lin_data;
    tui8 *lout_data;

    des3_ctx = (EVP_CIPHER_CTX *) des3;
    if (des3_ctx != NULL)
    {
        lin_data = (const tui8 *) in_data;
        lout_data = (tui8 *) out_data;
        len = 0;
        EVP_DecryptUpdate(des3_ctx, lout_data, &len, lin_data, length);
    }
    return 0;
}

/*****************************************************************************/
void *
ssl_hmac_info_create(void)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    return (HMAC_CTX *)HMAC_CTX_new();
#else
    /* Need a MAC algorithm loaded */
    if (g_mac_hmac == NULL)
    {
        if ((g_mac_hmac = EVP_MAC_fetch(NULL, "hmac", NULL)) == NULL)
        {
            dump_error_stack("hmac");
            return NULL;
        }
    }

    return (void *)EVP_MAC_CTX_new(g_mac_hmac);
#endif
}

/*****************************************************************************/
void
ssl_hmac_info_delete(void *hmac)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    HMAC_CTX *hmac_ctx;

    hmac_ctx = (HMAC_CTX *) hmac;
    if (hmac_ctx != 0)
    {
        HMAC_CTX_free(hmac_ctx);
    }
#else
    EVP_MAC_CTX_free((EVP_MAC_CTX *)hmac);
#endif
}

/*****************************************************************************/
void
ssl_hmac_sha1_init(void *hmac, const char *data, int len)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    HMAC_CTX *hmac_ctx;

    hmac_ctx = (HMAC_CTX *) hmac;
    HMAC_Init_ex(hmac_ctx, data, len, EVP_sha1(), NULL);
#else
    if (hmac != NULL)
    {
        char digest[] = "sha1";
        OSSL_PARAM params[3];
        size_t n = 0;
        params[n++] = OSSL_PARAM_construct_utf8_string("digest", digest, 0);
        params[n++] = OSSL_PARAM_construct_end();
        if (EVP_MAC_init((EVP_MAC_CTX *)hmac, (unsigned char *)data,
                         len, params) == 0)
        {
            dump_error_stack("hmac-sha1");
        }
    }
#endif
}

/*****************************************************************************/
void
ssl_hmac_transform(void *hmac, const char *data, int len)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    HMAC_CTX *hmac_ctx;
    const tui8 *ldata;

    hmac_ctx = (HMAC_CTX *) hmac;
    ldata = (const tui8 *) data;
    HMAC_Update(hmac_ctx, ldata, len);
#else
    if (hmac != NULL)
    {
        EVP_MAC_update((EVP_MAC_CTX *)hmac, (unsigned char *)data, len);
    }
#endif
}

/*****************************************************************************/
void
ssl_hmac_complete(void *hmac, char *data, int len)
{
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    HMAC_CTX *hmac_ctx;
    tui8 *ldata;
    tui32 llen;

    hmac_ctx = (HMAC_CTX *) hmac;
    ldata = (tui8 *) data;
    llen = len;
    HMAC_Final(hmac_ctx, ldata, &llen);
#else
    if (hmac != NULL)
    {
        EVP_MAC_final((EVP_MAC_CTX *)hmac, (unsigned char *)data, NULL, len);
    }
#endif
}

/*****************************************************************************/
static void
ssl_reverse_it(char *p, int len)
{
    int i;
    int j;
    char temp;

    i = 0;
    j = len - 1;

    while (i < j)
    {
        temp = p[i];
        p[i] = p[j];
        p[j] = temp;
        i++;
        j--;
    }
}

/*****************************************************************************/
int
ssl_mod_exp(char *out, int out_len, const char *in, int in_len,
            const char *mod, int mod_len, const char *exp, int exp_len)
{
    BN_CTX *ctx;
    BIGNUM *lmod;
    BIGNUM *lexp;
    BIGNUM *lin;
    BIGNUM *lout;
    int rv;
    char *l_out;
    char *l_in;
    char *l_mod;
    char *l_exp;

    l_out = (char *)g_malloc(out_len, 1);
    l_in = (char *)g_malloc(in_len, 1);
    l_mod = (char *)g_malloc(mod_len, 1);
    l_exp = (char *)g_malloc(exp_len, 1);
    g_memcpy(l_in, in, in_len);
    g_memcpy(l_mod, mod, mod_len);
    g_memcpy(l_exp, exp, exp_len);
    ssl_reverse_it(l_in, in_len);
    ssl_reverse_it(l_mod, mod_len);
    ssl_reverse_it(l_exp, exp_len);
    ctx = BN_CTX_new();
    lmod = BN_new();
    lexp = BN_new();
    lin = BN_new();
    lout = BN_new();
    BN_bin2bn((tui8 *)l_mod, mod_len, lmod);
    BN_bin2bn((tui8 *)l_exp, exp_len, lexp);
    BN_bin2bn((tui8 *)l_in, in_len, lin);
    BN_mod_exp(lout, lin, lexp, lmod, ctx);
    rv = BN_bn2bin(lout, (tui8 *)l_out);

    if (rv <= out_len)
    {
        ssl_reverse_it(l_out, rv);
        g_memcpy(out, l_out, out_len);
    }
    else
    {
        rv = 0;
    }

    BN_free(lin);
    BN_free(lout);
    BN_free(lexp);
    BN_free(lmod);
    BN_CTX_free(ctx);
    g_free(l_out);
    g_free(l_in);
    g_free(l_mod);
    g_free(l_exp);
    return rv;
}

/*****************************************************************************/
/* returns error
   generates a new rsa key
   exp is passed in and mod and pri are passed out */
int
ssl_gen_key_xrdp1(int key_size_in_bits, const char *exp, int exp_len,
                  char *mod, int mod_len, char *pri, int pri_len)
{
    BIGNUM *my_e;
    char *lexp;
    char *lmod;
    char *lpri;
    int error;
    int len;
    int diff;

    if ((exp_len != 4) || ((mod_len != 64) && (mod_len != 256)) ||
            ((pri_len != 64) && (pri_len != 256)))
    {
        return 1;
    }

    diff = 0;
    lexp = (char *)g_malloc(exp_len, 1);
    lmod = (char *)g_malloc(mod_len, 1);
    lpri = (char *)g_malloc(pri_len, 1);
    g_memcpy(lexp, exp, exp_len);
    ssl_reverse_it(lexp, exp_len);
    my_e = BN_new();
    BN_bin2bn((tui8 *)lexp, exp_len, my_e);

#if OPENSSL_VERSION_NUMBER < 0x30000000L
    const BIGNUM *n = NULL;
    const BIGNUM *d = NULL;
    RSA *my_key = RSA_new();
    error = RSA_generate_key_ex(my_key, key_size_in_bits, my_e, 0) == 0;

    /* After this call, n and d point directly into my_key, and are valid
     * until my_key is free'd */
    RSA_get0_key(my_key, &n, NULL, &d);
#else
    BIGNUM *n = NULL;
    BIGNUM *d = NULL;
    OSSL_PARAM params[] =
    {
        OSSL_PARAM_construct_int("bits", &key_size_in_bits),
        OSSL_PARAM_construct_end()
    };
    EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_from_name(NULL, "RSA", NULL);
    EVP_PKEY *pkey = NULL;

    if (pctx != NULL &&
            EVP_PKEY_keygen_init(pctx) > 0 &&
            EVP_PKEY_CTX_set_params(pctx, params) > 0 &&
            EVP_PKEY_generate(pctx, &pkey) > 0 &&
            EVP_PKEY_get_bn_param(pkey, "n", &n) > 0 &&
            EVP_PKEY_get_bn_param(pkey, "d", &d) > 0)
    {
        error = 0;
    }
    else
    {
        error = 1;
    }

    EVP_PKEY_CTX_free(pctx);
    EVP_PKEY_free(pkey);
#endif

    if (error == 0)
    {
        len = BN_num_bytes(n);
        error = (len < 1) || (len > mod_len);
        diff = mod_len - len;
    }

    if (error == 0)
    {
        BN_bn2bin(n, (tui8 *)(lmod + diff));
        ssl_reverse_it(lmod, mod_len);
    }

    if (error == 0)
    {
        len = BN_num_bytes(d);
        error = (len < 1) || (len > pri_len);
        diff = pri_len - len;
    }

    if (error == 0)
    {
        BN_bn2bin(d, (tui8 *)(lpri + diff));
        ssl_reverse_it(lpri, pri_len);
    }

    if (error == 0)
    {
        g_memcpy(mod, lmod, mod_len);
        g_memcpy(pri, lpri, pri_len);
    }

    BN_free(my_e);
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    RSA_free(my_key);
#else
    BN_free(n);
    BN_clear_free(d);
#endif
    g_free(lexp);
    g_free(lmod);
    g_free(lpri);
    return error;
}

/*****************************************************************************/
/** static DH parameter, can be used if no custom parameter is specified
see also
 * https://wiki.openssl.org/index.php/Diffie-Hellman_parameters
 * https://wiki.openssl.org/index.php/Manual:SSL_CTX_set_tmp_dh_callback(3)
 *
 * We dont do this for OpenSSL 3 - we use SSL_CTX_set_dh_auto() instead, as this
 * can cater for different key sizes on the certificate
*/
#if OPENSSL_VERSION_NUMBER < 0x30000000L
static DH *ssl_get_dh2236()
{
    static unsigned char dh2236_p[] =
    {
        0x0E, 0xF8, 0x69, 0x0B, 0x35, 0x2F, 0x62, 0x59, 0xF7, 0xAF, 0x4E, 0x19,
        0xB5, 0x9B, 0xD2, 0xEB, 0x33, 0x78, 0x1D, 0x43, 0x1D, 0xB6, 0xE4, 0xA3,
        0x63, 0x47, 0x6A, 0xD4, 0xA8, 0x28, 0x11, 0x8C, 0x3F, 0xC8, 0xF1, 0x32,
        0x2B, 0x5D, 0x9F, 0xF8, 0xA6, 0xCA, 0x21, 0x71, 0xDE, 0x30, 0xD7, 0xB5,
        0xD6, 0xA4, 0xC2, 0xEE, 0xC0, 0x49, 0x30, 0xE7, 0x8C, 0x9B, 0x1A, 0x5A,
        0x08, 0x2A, 0x11, 0x84, 0xE2, 0xC8, 0x36, 0x6C, 0xDC, 0x06, 0x79, 0x59,
        0x51, 0xA4, 0xA0, 0x8F, 0xE1, 0x20, 0x94, 0x80, 0xAC, 0x6D, 0xFD, 0x3B,
        0xA6, 0xA6, 0x70, 0x51, 0x93, 0x59, 0x28, 0x51, 0x54, 0xA3, 0xC5, 0x15,
        0x44, 0x2C, 0x12, 0xE7, 0x95, 0x62, 0x0E, 0x65, 0x2F, 0x8C, 0x0D, 0xF8,
        0x63, 0x52, 0x00, 0x2A, 0xA5, 0xD7, 0x59, 0xEF, 0x13, 0x18, 0x33, 0x25,
        0xBC, 0xAD, 0xC8, 0x0A, 0x72, 0x8D, 0x26, 0x63, 0xD5, 0xB3, 0xBC, 0x43,
        0x35, 0x0B, 0x5D, 0xC7, 0xCA, 0x45, 0x17, 0x06, 0x24, 0x71, 0xCA, 0x20,
        0x73, 0xE8, 0x18, 0xD3, 0x8E, 0xE9, 0xE9, 0x8F, 0x67, 0xC0, 0x2C, 0x14,
        0x7E, 0x41, 0x18, 0x6C, 0x74, 0x72, 0x56, 0x34, 0xC0, 0xDB, 0xDD, 0x85,
        0x8B, 0xE0, 0x99, 0xE8, 0x5E, 0xC8, 0xF7, 0xD1, 0x0C, 0xF8, 0x83, 0x34,
        0x37, 0x9E, 0x01, 0xDF, 0x1C, 0xD9, 0xE9, 0x95, 0xC1, 0x4C, 0x64, 0x37,
        0x9B, 0xF5, 0x8F, 0x99, 0x97, 0x55, 0x68, 0x2E, 0x23, 0xB0, 0x35, 0xF3,
        0xA5, 0x97, 0x92, 0xA0, 0x6D, 0xB4, 0xF8, 0xD8, 0x47, 0xCE, 0x3F, 0x0B,
        0x36, 0x0E, 0xEB, 0x13, 0x15, 0xFD, 0x4F, 0x98, 0x4F, 0x14, 0x26, 0xE2,
        0xAC, 0xD9, 0x42, 0xC6, 0x43, 0x8A, 0x95, 0x6B, 0x2B, 0x44, 0x38, 0x7F,
        0x60, 0x97, 0x77, 0xD8, 0x7C, 0x6F, 0x5D, 0x62, 0x7C, 0xE1, 0xC8, 0x83,
        0x12, 0x8B, 0x5E, 0x5E, 0xC7, 0x5E, 0xD5, 0x60, 0xF3, 0x2F, 0xFC, 0xFE,
        0x70, 0xAC, 0x58, 0x3A, 0x3C, 0x18, 0x15, 0x54, 0x84, 0xA8, 0xAA, 0x41,
        0x26, 0x7B, 0xE0, 0xA3,
    };
    static unsigned char dh2236_g[] =
    {
        0x02,
    };

    DH *dh = DH_new();
    if (dh == NULL)
    {
        return NULL;
    }

    BIGNUM *p = BN_bin2bn(dh2236_p, sizeof(dh2236_p), NULL);
    BIGNUM *g = BN_bin2bn(dh2236_g, sizeof(dh2236_g), NULL);
    if (p == NULL || g == NULL)
    {
        BN_free(p);
        BN_free(g);
        DH_free(dh);
        return NULL;
    }

    // p, g are freed later by DH_free()
    if (0 == DH_set0_pqg(dh, p, NULL, g))
    {
        BN_free(p);
        BN_free(g);
        DH_free(dh);
        return NULL;
    }

    return dh;
}
#endif /* OPENSSL_VERSION_NUMBER < 0x30000000L */

/*****************************************************************************/
struct ssl_tls *
ssl_tls_create(struct trans *trans, const char *key, const char *cert)
{
    struct ssl_tls *self;
    int pid;
    char buf[1024];

    self = (struct ssl_tls *) g_malloc(sizeof(struct ssl_tls), 1);
    if (self != NULL)
    {
        self->trans = trans;
        self->cert = (char *) cert;
        self->key = (char *) key;
        pid = g_getpid();
        g_snprintf(buf, 1024, "xrdp_%8.8x_tls_rwo", pid);
        self->rwo = g_create_wait_obj(buf);
    }

    return self;
}
/*****************************************************************************/
static int
ssl_tls_log_error(struct ssl_tls *self, const char *func, int value)
{
    int result = 1;
    int ssl_error = SSL_get_error(self->ssl, value);

    if (ssl_error == SSL_ERROR_WANT_READ || ssl_error == SSL_ERROR_WANT_WRITE)
    {
        result = 0;
    }
    else if (!self->error_logged)
    {
        switch (ssl_error)
        {
            case SSL_ERROR_ZERO_RETURN:
                LOG(LOG_LEVEL_ERROR, "%s: Server closed TLS connection", func);
                break;

            case SSL_ERROR_SYSCALL:
                LOG(LOG_LEVEL_ERROR, "%s: I/O error", func);
                break;

            case SSL_ERROR_SSL:
                LOG(LOG_LEVEL_ERROR, "%s: Failure in SSL library "
                    "(protocol error?)", func);
                break;

            default:
                LOG(LOG_LEVEL_ERROR, "%s: Unknown SSL error", func);
                break;
        }

        dump_ssl_error_stack(self); /* Sets self->error_logged */
    }

    return result;
}

/**************************************************************************//**
 * Log an attempt to use an encrypted file
 *
 * For example, a private key could have a password set on it. We don't
 * support this.
 */
static int
log_encrypted_file_unsupported(char *buf, int size, int rwflag, void *u)
{
    LOG(LOG_LEVEL_ERROR, "Encryption is not supported for %s",
        (const char *)u);
    return -1; /* See pem_password_cb(3ssl) */
}

/*****************************************************************************/

int
ssl_tls_accept(struct ssl_tls *self, long ssl_protocols,
               const char *tls_ciphers)
{
    int connection_status;
    long options = 0;

    ERR_clear_error();

    /**
     * SSL_OP_NO_SSLv2
     * SSLv3 is used by, eg. Microsoft RDC for Mac OS X.
     */
    options |= SSL_OP_NO_SSLv2;

    /**
     * Disable SSL protocols not listed in ssl_protocols.
     */
    options |= ssl_protocols;


#if defined(SSL_OP_NO_COMPRESSION)
    /**
     * SSL_OP_NO_COMPRESSION:
     *
     * The Microsoft RDP server does not advertise support
     * for TLS compression, but alternative servers may support it.
     * This was observed between early versions of the FreeRDP server
     * and the FreeRDP client, and caused major performance issues,
     * which is why we're disabling it.
     */
    options |= SSL_OP_NO_COMPRESSION;
#endif

    /**
     * SSL_OP_TLS_BLOCK_PADDING_BUG:
     *
     * The Microsoft RDP server does *not* support TLS padding.
     * It absolutely needs to be disabled otherwise it won't work.
     */
    options |= SSL_OP_TLS_BLOCK_PADDING_BUG;

    /**
     * SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS:
     *
     * Just like TLS padding, the Microsoft RDP server does not
     * support empty fragments. This needs to be disabled.
     */
    options |= SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS;

    self->ctx = SSL_CTX_new(SSLv23_server_method());
    if (self->ctx == NULL)
    {
        LOG(LOG_LEVEL_ERROR, "Unable to negotiate a TLS connection with the client");
        dump_ssl_error_stack(self);
        return 1;
    }

    /* set context options */
    SSL_CTX_set_mode(self->ctx,
                     SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER |
                     SSL_MODE_ENABLE_PARTIAL_WRITE);
    SSL_CTX_set_options(self->ctx, options);

    /* set DH parameters */
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    DH *dh = ssl_get_dh2236();
    if (dh == NULL)
    {
        LOG(LOG_LEVEL_ERROR, "Unable to generate DHE parameters for TLS");
        return 1;
    }

    if (SSL_CTX_set_tmp_dh(self->ctx, dh) != 1)
    {
        LOG(LOG_LEVEL_ERROR, "Unable to setup DHE parameters for TLS");
        dump_ssl_error_stack(self);
        return 1;
    }
    DH_free(dh); // ok to free, copied into ctx by SSL_CTX_set_tmp_dh()
#else
    if (!SSL_CTX_set_dh_auto(self->ctx, 1))
    {
        LOG(LOG_LEVEL_ERROR, "TLS DHE auto failed to be enabled");
        dump_ssl_error_stack(self);
        return 1;
    }
#endif
#if defined(SSL_CTX_set_ecdh_auto)
    if (!SSL_CTX_set_ecdh_auto(self->ctx, 1))
    {
        LOG(LOG_LEVEL_WARNING, "TLS ecdh auto failed to be enabled");
    }
#endif

    if (g_strlen(tls_ciphers) > 1)
    {
        LOG(LOG_LEVEL_TRACE, "tls_ciphers=%s", tls_ciphers);
        if (SSL_CTX_set_cipher_list(self->ctx, tls_ciphers) == 0)
        {
            LOG(LOG_LEVEL_ERROR, "Invalid TLS cipher options %s", tls_ciphers);
            dump_ssl_error_stack(self);
            return 1;
        }
    }

    SSL_CTX_set_read_ahead(self->ctx, 0);

    /*
     * We don't currently handle encrypted private keys - set a callback
     * to tell the user if one is provided */
    SSL_CTX_set_default_passwd_cb(self->ctx, log_encrypted_file_unsupported);
    SSL_CTX_set_default_passwd_cb_userdata(self->ctx, self->key);

    if (SSL_CTX_use_PrivateKey_file(self->ctx, self->key, SSL_FILETYPE_PEM)
            <= 0)
    {
        LOG(LOG_LEVEL_ERROR, "Error loading TLS private key from %s", self->key);
        dump_ssl_error_stack(self);
        return 1;
    }
    SSL_CTX_set_default_passwd_cb(self->ctx, NULL);
    SSL_CTX_set_default_passwd_cb_userdata(self->ctx, NULL);

    if (SSL_CTX_use_certificate_chain_file(self->ctx, self->cert) <= 0)
    {
        LOG(LOG_LEVEL_ERROR, "Error loading TLS certificate chain from %s", self->cert);
        dump_ssl_error_stack(self);
        return 1;
    }

    /*
     * Don't call SSL_check_private_key() for openSSL prior to 1.0.2, as
     * certificate chains are not handled in the same way - see
     * SSL_CTX_check_private_key(3ssl) */
#if OPENSSL_VERSION_NUMBER >= 0x10002000L
    if (!SSL_CTX_check_private_key(self->ctx))
    {
        LOG(LOG_LEVEL_ERROR, "Private key %s and certificate %s do not match",
            self->key, self->cert);
        dump_ssl_error_stack(self);
        return 1;
    }
#endif

    self->ssl = SSL_new(self->ctx);

    if (self->ssl == NULL)
    {
        LOG(LOG_LEVEL_ERROR, "Unable to create an SSL structure");
        dump_ssl_error_stack(self);
        return 1;
    }

    if (SSL_set_fd(self->ssl, self->trans->sck) < 1)
    {
        LOG(LOG_LEVEL_ERROR, "Unable to set up an SSL structure on fd %d",
            (int)self->trans->sck);
        dump_ssl_error_stack(self);
        return 1;
    }

    while (1)
    {
        /*
         * Make sure the error queue is clear before (re-) attempting the
         * accept. If the accept is successful, the error queue will
         * remain clear for normal SSL operation */
        ERR_clear_error();

        connection_status = SSL_accept(self->ssl);

        if (connection_status <= 0)
        {
            if (ssl_tls_log_error(self, "SSL_accept", connection_status))
            {
                return 1;
            }
            /**
             * retry when SSL_get_error returns:
             *     SSL_ERROR_WANT_READ
             *     SSL_ERROR_WANT_WRITE
             */
            switch (SSL_get_error(self->ssl, connection_status))
            {
                case SSL_ERROR_WANT_READ:
                    g_sck_can_recv(self->trans->sck, SSL_WANT_READ_WRITE_TIMEOUT);
                    break;
                case SSL_ERROR_WANT_WRITE:
                    g_sck_can_send(self->trans->sck, SSL_WANT_READ_WRITE_TIMEOUT);
                    break;
            }
        }
        else
        {
            break;
        }
    }

    LOG(LOG_LEVEL_TRACE, "TLS connection accepted");

    return 0;
}

/*****************************************************************************/
/* returns error, */
int
ssl_tls_disconnect(struct ssl_tls *self)
{
    int status;

    if (self == NULL)
    {
        return 0;
    }
    if (self->ssl == NULL)
    {
        return 0;
    }
    status = SSL_shutdown(self->ssl);
    if (status != 1)
    {
        status = SSL_shutdown(self->ssl);
        if (status <= 0)
        {
            if (ssl_tls_log_error(self, "SSL_shutdown", status))
            {
                return 1;
            }
            /**
             * retry when SSL_get_error returns:
             *     SSL_ERROR_WANT_READ
             *     SSL_ERROR_WANT_WRITE
             */
        }
    }
    return 0;
}

/*****************************************************************************/
void
ssl_tls_delete(struct ssl_tls *self)
{
    if (self != NULL)
    {
        if (self->ssl)
        {
            SSL_free(self->ssl);
        }

        if (self->ctx)
        {
            SSL_CTX_free(self->ctx);
        }

        g_delete_wait_obj(self->rwo);

        g_free(self);
    }
}

/*****************************************************************************/
int
ssl_tls_read(struct ssl_tls *tls, char *data, int length)
{
    int status;
    int break_flag;

    while (1)
    {
        status = SSL_read(tls->ssl, data, length);

        switch (SSL_get_error(tls->ssl, status))
        {
            case SSL_ERROR_NONE:
                break_flag = 1;
                break;

            /**
             * retry when SSL_get_error returns:
             *     SSL_ERROR_WANT_READ
             *     SSL_ERROR_WANT_WRITE
             */
            case SSL_ERROR_WANT_READ:
                g_sck_can_recv(tls->trans->sck, SSL_WANT_READ_WRITE_TIMEOUT);
                continue;
            case SSL_ERROR_WANT_WRITE:
                g_sck_can_send(tls->trans->sck, SSL_WANT_READ_WRITE_TIMEOUT);
                continue;

            /* socket closed */
            case SSL_ERROR_ZERO_RETURN:
                return 0;

            default:
                ssl_tls_log_error(tls, "SSL_read", status);
                status = -1;
                break_flag = 1;
                break;
        }

        if (break_flag)
        {
            break;
        }
    }

    if (SSL_pending(tls->ssl) > 0)
    {
        g_set_wait_obj(tls->rwo);
    }

    return status;
}

/*****************************************************************************/
int
ssl_tls_write(struct ssl_tls *tls, const char *data, int length)
{
    int status;
    int break_flag;

    while (1)
    {
        status = SSL_write(tls->ssl, data, length);

        switch (SSL_get_error(tls->ssl, status))
        {
            case SSL_ERROR_NONE:
                break_flag = 1;
                break;

            /**
             * retry when SSL_get_error returns:
             *     SSL_ERROR_WANT_READ
             *     SSL_ERROR_WANT_WRITE
             */
            case SSL_ERROR_WANT_READ:
                g_sck_can_recv(tls->trans->sck, SSL_WANT_READ_WRITE_TIMEOUT);
                continue;
            case SSL_ERROR_WANT_WRITE:
                g_sck_can_send(tls->trans->sck, SSL_WANT_READ_WRITE_TIMEOUT);
                continue;

            /* socket closed */
            case SSL_ERROR_ZERO_RETURN:
                return 0;

            default:
                ssl_tls_log_error(tls, "SSL_write", status);
                status = -1;
                break_flag = 1;
                break;
        }

        if (break_flag)
        {
            break;
        }
    }

    return status;
}

/*****************************************************************************/
/* returns boolean */
int
ssl_tls_can_recv(struct ssl_tls *tls, int sck, int millis)
{
    if (SSL_pending(tls->ssl) > 0)
    {
        return 1;
    }
    g_reset_wait_obj(tls->rwo);
    return g_sck_can_recv(sck, millis);
}

/*****************************************************************************/
const char *
ssl_get_version(const struct ssl_tls *ssl)
{
    return SSL_get_version(ssl->ssl);
}

/*****************************************************************************/
const char *
ssl_get_cipher_name(const struct ssl_tls *ssl)
{
    return SSL_get_cipher_name(ssl->ssl);
}

/*****************************************************************************/
tintptr
ssl_get_rwo(const struct ssl_tls *ssl)
{
    return ssl->rwo;
}

/*****************************************************************************/
int
ssl_get_protocols_from_string(const char *str, long *ssl_protocols)
{
    long protocols;
    long bad_protocols;
    int rv;

    if ((str == NULL) || (ssl_protocols == NULL))
    {
        return 1;
    }
    rv = 0;
    protocols = 0;
#if defined(SSL_OP_NO_SSLv3)
    protocols |= SSL_OP_NO_SSLv3;
#endif
#if defined(SSL_OP_NO_TLSv1)
    protocols |= SSL_OP_NO_TLSv1;
#endif
#if defined(SSL_OP_NO_TLSv1_1)
    protocols |= SSL_OP_NO_TLSv1_1;
#endif
#if defined(SSL_OP_NO_TLSv1_2)
    protocols |= SSL_OP_NO_TLSv1_2;
#endif
#if defined(SSL_OP_NO_TLSv1_3)
    protocols |= SSL_OP_NO_TLSv1_3;
#endif
    bad_protocols = protocols;
    if (g_pos(str, ",TLSv1.3,") >= 0)
    {
#if defined(SSL_OP_NO_TLSv1_3)
        LOG(LOG_LEVEL_DEBUG, "TLSv1.3 enabled");
        protocols &= ~SSL_OP_NO_TLSv1_3;
#else
        LOG(LOG_LEVEL_WARNING,
            "TLSv1.3 enabled by config, "
            "but not supported by system OpenSSL");
        rv |= (1 << 6);
#endif
    }
    if (g_pos(str, ",TLSv1.2,") >= 0)
    {
#if defined(SSL_OP_NO_TLSv1_2)
        LOG(LOG_LEVEL_DEBUG, "TLSv1.2 enabled");
        protocols &= ~SSL_OP_NO_TLSv1_2;
#else
        LOG(LOG_LEVEL_WARNING,
            "TLSv1.2 enabled by config, "
            "but not supported by system OpenSSL");
        rv |= (1 << 1);
#endif
    }
    if (g_pos(str, ",TLSv1.1,") >= 0)
    {
#if defined(SSL_OP_NO_TLSv1_1)
        LOG(LOG_LEVEL_DEBUG, "TLSv1.1 enabled");
        protocols &= ~SSL_OP_NO_TLSv1_1;
#else
        LOG(LOG_LEVEL_WARNING,
            "TLSv1.1 enabled by config, "
            "but not supported by system OpenSSL");
        rv |= (1 << 2);
#endif
    }
    if (g_pos(str, ",TLSv1,") >= 0)
    {
#if defined(SSL_OP_NO_TLSv1)
        LOG(LOG_LEVEL_DEBUG, "TLSv1 enabled");
        protocols &= ~SSL_OP_NO_TLSv1;
#else
        LOG(LOG_LEVEL_WARNING,
            "TLSv1 enabled by config, "
            "but not supported by system OpenSSL");
        rv |= (1 << 3);
#endif
    }
    if (g_pos(str, ",SSLv3,") >= 0)
    {
#if defined(SSL_OP_NO_SSLv3)
        LOG(LOG_LEVEL_DEBUG, "SSLv3 enabled");
        protocols &= ~SSL_OP_NO_SSLv3;
#else
        LOG(LOG_LEVEL_WARNING,
            "SSLv3 enabled by config, "
            "but not supported by system OpenSSL");
        rv |= (1 << 4);
#endif
    }
    if (protocols == bad_protocols)
    {
        LOG(LOG_LEVEL_WARNING, "No SSL/TLS protocols enabled. "
            "At least one protocol should be enabled to accept "
            "TLS connections.");
        rv |= (1 << 5);
    }
    *ssl_protocols = protocols;
    return rv;
}

/*****************************************************************************/
const char
*get_openssl_version(void)
{
#if OPENSSL_VERSION_NUMBER < 0x10100000L
    return SSLeay_version(SSLEAY_VERSION);
#else
    return OpenSSL_version(OPENSSL_VERSION);
#endif

}