/*

 * wrapper.c - wrapper for crytpo functions

 *

 * This file is part of the SSH Library

 *

 * Copyright (c) 2003-2013   by Aris Adamantiadis

 *

 * The SSH Library is free software; you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation; either version 2.1 of the License, or (at your

 * option) any later version.

 *

 * The SSH Library is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public

 * License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with the SSH Library; see the file COPYING.  If not, write to

 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,

 * MA 02111-1307, USA.

 */

/*

 * Why a wrapper?

 *

 * Let's say you want to port libssh from libcrypto of openssl to libfoo

 * you are going to spend hours to remove every references to SHA1_Update()

 * to libfoo_sha1_update after the work is finished, you're going to have

 * only this file to modify it's not needed to say that your modifications

 * are welcome.

 */

#include "config.h"

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#ifdef WITH_ZLIB

#include <zlib.h>

#endif

#include "libssh/priv.h"

#include "libssh/session.h"

#include "libssh/crypto.h"

#include "libssh/wrapper.h"

#include "libssh/pki.h"

#include "libssh/poly1305.h"

#include "libssh/dh.h"

#ifdef WITH_GEX

#include "libssh/dh-gex.h"

#endif /* WITH_GEX */

#include "libssh/ecdh.h"

#include "libssh/curve25519.h"

static struct ssh_hmac_struct ssh_hmac_tab[] = {

  { "hmac-sha1",                     SSH_HMAC_SHA1,          false },

  { "hmac-sha2-256",                 SSH_HMAC_SHA256,        false },

  { "hmac-sha2-512",                 SSH_HMAC_SHA512,        false },

  { "hmac-md5",                      SSH_HMAC_MD5,           false },

  { "aead-poly1305",                 SSH_HMAC_AEAD_POLY1305, false },

  { "aead-gcm",                      SSH_HMAC_AEAD_GCM,      false },

  { "hmac-sha1-etm@openssh.com",     SSH_HMAC_SHA1,          true  },

  { "hmac-sha2-256-etm@openssh.com", SSH_HMAC_SHA256,        true  },

  { "hmac-sha2-512-etm@openssh.com", SSH_HMAC_SHA512,        true  },

  { "hmac-md5-etm@openssh.com",      SSH_HMAC_MD5,           true  },

  { NULL,                            0,                      false }

};

struct ssh_hmac_struct *ssh_get_hmactab(void) {

  return ssh_hmac_tab;

}

size_t hmac_digest_len(enum ssh_hmac_e type) {

  switch(type) {

    case SSH_HMAC_SHA1:

      return SHA_DIGEST_LEN;

    case SSH_HMAC_SHA256:

      return SHA256_DIGEST_LEN;

    case SSH_HMAC_SHA512:

      return SHA512_DIGEST_LEN;

    case SSH_HMAC_MD5:

      return MD5_DIGEST_LEN;

    case SSH_HMAC_AEAD_POLY1305:

      return POLY1305_TAGLEN;

    case SSH_HMAC_AEAD_GCM:

      return AES_GCM_TAGLEN;

    default:

      return 0;

  }

}

const char *ssh_hmac_type_to_string(enum ssh_hmac_e hmac_type, bool etm)

{

  int i = 0;

  struct ssh_hmac_struct *ssh_hmactab = ssh_get_hmactab();

  while (ssh_hmactab[i].name &&

         ((ssh_hmactab[i].hmac_type != hmac_type) ||

          (ssh_hmactab[i].etm != etm))) {

    i++;

  }

  return ssh_hmactab[i].name;

}

/* it allocates a new cipher structure based on its offset into the global table */

static struct ssh_cipher_struct *cipher_new(int offset) {

  struct ssh_cipher_struct *cipher = NULL;

  cipher = malloc(sizeof(struct ssh_cipher_struct));

  if (cipher == NULL) {

    return NULL;

  }

  /* note the memcpy will copy the pointers : so, you shouldn't free them */

  memcpy(cipher, &ssh_get_ciphertab()[offset], sizeof(*cipher));

  return cipher;

}

void ssh_cipher_clear(struct ssh_cipher_struct *cipher){

#ifdef HAVE_LIBGCRYPT

    unsigned int i;

#endif

    if (cipher == NULL) {

        return;

    }

#ifdef HAVE_LIBGCRYPT

    if (cipher->key) {

        for (i = 0; i < (cipher->keylen / sizeof(gcry_cipher_hd_t)); i++) {

            gcry_cipher_close(cipher->key[i]);

        }

        SAFE_FREE(cipher->key);

    }

#endif

    if (cipher->cleanup != NULL) {

        cipher->cleanup(cipher);

    }

}

static void cipher_free(struct ssh_cipher_struct *cipher) {

  ssh_cipher_clear(cipher);

  SAFE_FREE(cipher);

}

struct ssh_crypto_struct *crypto_new(void) {

   struct ssh_crypto_struct *crypto;

  crypto = malloc(sizeof(struct ssh_crypto_struct));

  if (crypto == NULL) {

    return NULL;

  }

  ZERO_STRUCTP(crypto);

  return crypto;

}

void crypto_free(struct ssh_crypto_struct *crypto)

{

    size_t i;

    if (crypto == NULL) {

        return;

    }

    ssh_key_free(crypto->server_pubkey);

    ssh_dh_cleanup(crypto);

    bignum_safe_free(crypto->shared_secret);

#ifdef HAVE_ECDH

    SAFE_FREE(crypto->ecdh_client_pubkey);

    SAFE_FREE(crypto->ecdh_server_pubkey);

    if(crypto->ecdh_privkey != NULL){

#ifdef HAVE_OPENSSL_ECC

        EC_KEY_free(crypto->ecdh_privkey);

#elif defined HAVE_GCRYPT_ECC

        gcry_sexp_release(crypto->ecdh_privkey);

#endif

        crypto->ecdh_privkey = NULL;

    }

#endif

    if (crypto->session_id != NULL) {

        explicit_bzero(crypto->session_id, crypto->digest_len);

        SAFE_FREE(crypto->session_id);

    }

    if (crypto->secret_hash != NULL) {

        explicit_bzero(crypto->secret_hash, crypto->digest_len);

        SAFE_FREE(crypto->secret_hash);

    }

#ifdef WITH_ZLIB

    if (crypto->compress_out_ctx &&

        (deflateEnd(crypto->compress_out_ctx) != 0)) {

        inflateEnd(crypto->compress_out_ctx);

    }

    SAFE_FREE(crypto->compress_out_ctx);

    if (crypto->compress_in_ctx &&

        (deflateEnd(crypto->compress_in_ctx) != 0)) {

        inflateEnd(crypto->compress_in_ctx);

    }

    SAFE_FREE(crypto->compress_in_ctx);

#endif /* WITH_ZLIB */

    SAFE_FREE(crypto->encryptIV);

    SAFE_FREE(crypto->decryptIV);

    SAFE_FREE(crypto->encryptMAC);

    SAFE_FREE(crypto->decryptMAC);

    if (crypto->encryptkey != NULL) {

        explicit_bzero(crypto->encryptkey, crypto->out_cipher->keysize / 8);

        SAFE_FREE(crypto->encryptkey);

    }

    if (crypto->decryptkey != NULL) {

        explicit_bzero(crypto->decryptkey, crypto->in_cipher->keysize / 8);

        SAFE_FREE(crypto->decryptkey);

    }

    cipher_free(crypto->in_cipher);

    cipher_free(crypto->out_cipher);

    for (i = 0; i < SSH_KEX_METHODS; i++) {

        SAFE_FREE(crypto->client_kex.methods[i]);

        SAFE_FREE(crypto->server_kex.methods[i]);

        SAFE_FREE(crypto->kex_methods[i]);

    }

    explicit_bzero(crypto, sizeof(struct ssh_crypto_struct));

    SAFE_FREE(crypto);

}

static int crypt_set_algorithms2(ssh_session session)

{

    const char *wanted = NULL;

    struct ssh_cipher_struct *ssh_ciphertab=ssh_get_ciphertab();

    struct ssh_hmac_struct *ssh_hmactab=ssh_get_hmactab();

    size_t i = 0;

    int cmp;

    /*

     * We must scan the kex entries to find crypto algorithms and set their

     * appropriate structure.

     */

    /* out */

    wanted = session->next_crypto->kex_methods[SSH_CRYPT_C_S];

    for (i = 0; i < 64 && ssh_ciphertab[i].name != NULL; ++i) {

        cmp = strcmp(wanted, ssh_ciphertab[i].name);

        if (cmp == 0) {

            break;

        }

    }

    if (ssh_ciphertab[i].name == NULL) {

        ssh_set_error(session, SSH_FATAL,

                "crypt_set_algorithms2: no crypto algorithm function found for %s",

                wanted);

        return SSH_ERROR;

    }

    SSH_LOG(SSH_LOG_PACKET, "Set output algorithm to %s", wanted);

    session->next_crypto->out_cipher = cipher_new(i);

    if (session->next_crypto->out_cipher == NULL) {

        ssh_set_error_oom(session);

        return SSH_ERROR;

    }

    if (session->next_crypto->out_cipher->aead_encrypt != NULL) {

        /* this cipher has integrated MAC */

        if (session->next_crypto->out_cipher->ciphertype == SSH_AEAD_CHACHA20_POLY1305) {

            wanted = "aead-poly1305";

        } else {

            wanted = "aead-gcm";

        }

    } else {

        /*

         * We must scan the kex entries to find hmac algorithms and set their

         * appropriate structure.

         */

        /* out */

        wanted = session->next_crypto->kex_methods[SSH_MAC_C_S];

    }

    for (i = 0; ssh_hmactab[i].name != NULL; i++) {

        cmp = strcmp(wanted, ssh_hmactab[i].name);

        if (cmp == 0) {

            break;

        }

    }

    if (ssh_hmactab[i].name == NULL) {

        ssh_set_error(session, SSH_FATAL,

                "crypt_set_algorithms2: no hmac algorithm function found for %s",

                wanted);

        return SSH_ERROR;

    }

    SSH_LOG(SSH_LOG_PACKET, "Set HMAC output algorithm to %s", wanted);

    session->next_crypto->out_hmac = ssh_hmactab[i].hmac_type;

    session->next_crypto->out_hmac_etm = ssh_hmactab[i].etm;

    /* in */

    wanted = session->next_crypto->kex_methods[SSH_CRYPT_S_C];

    for (i = 0; ssh_ciphertab[i].name != NULL; i++) {

        cmp = strcmp(wanted, ssh_ciphertab[i].name);

        if (cmp == 0) {

            break;

        }

    }

    if (ssh_ciphertab[i].name == NULL) {

        ssh_set_error(session, SSH_FATAL,

                "Crypt_set_algorithms: no crypto algorithm function found for %s",

                wanted);

        return SSH_ERROR;

    }

    SSH_LOG(SSH_LOG_PACKET, "Set input algorithm to %s", wanted);

    session->next_crypto->in_cipher = cipher_new(i);

    if (session->next_crypto->in_cipher == NULL) {

        ssh_set_error_oom(session);

        return SSH_ERROR;

    }

    if (session->next_crypto->in_cipher->aead_encrypt != NULL){

        /* this cipher has integrated MAC */

        if (session->next_crypto->in_cipher->ciphertype == SSH_AEAD_CHACHA20_POLY1305) {

            wanted = "aead-poly1305";

        } else {

            wanted = "aead-gcm";

        }

    } else {

        /* we must scan the kex entries to find hmac algorithms and set their appropriate structure */

        wanted = session->next_crypto->kex_methods[SSH_MAC_S_C];

    }

    for (i = 0; ssh_hmactab[i].name != NULL; i++) {

        cmp = strcmp(wanted, ssh_hmactab[i].name);

        if (cmp == 0) {

            break;

        }

    }

    if (ssh_hmactab[i].name == NULL) {

        ssh_set_error(session, SSH_FATAL,

                "crypt_set_algorithms2: no hmac algorithm function found for %s",

                wanted);

        return SSH_ERROR;

    }

    SSH_LOG(SSH_LOG_PACKET, "Set HMAC input algorithm to %s", wanted);

    session->next_crypto->in_hmac = ssh_hmactab[i].hmac_type;

    session->next_crypto->in_hmac_etm = ssh_hmactab[i].etm;

    /* compression */

    cmp = strcmp(session->next_crypto->kex_methods[SSH_COMP_C_S], "zlib");

    if (cmp == 0) {

        session->next_crypto->do_compress_out = 1;

    }

    cmp = strcmp(session->next_crypto->kex_methods[SSH_COMP_S_C], "zlib");

    if (cmp == 0) {

        session->next_crypto->do_compress_in = 1;

    }

    cmp = strcmp(session->next_crypto->kex_methods[SSH_COMP_C_S], "zlib@openssh.com");

    if (cmp == 0) {

        session->next_crypto->delayed_compress_out = 1;

    }

    cmp = strcmp(session->next_crypto->kex_methods[SSH_COMP_S_C], "zlib@openssh.com");

    if (cmp == 0) {

        session->next_crypto->delayed_compress_in = 1;

    }

    return SSH_OK;

}

int crypt_set_algorithms_client(ssh_session session)

{

    return crypt_set_algorithms2(session);

}

#ifdef WITH_SERVER

int crypt_set_algorithms_server(ssh_session session){

    const char *method = NULL;

    size_t i = 0;

    struct ssh_cipher_struct *ssh_ciphertab=ssh_get_ciphertab();

    struct ssh_hmac_struct   *ssh_hmactab=ssh_get_hmactab();

    int cmp;

    if (session == NULL) {

        return SSH_ERROR;

    }

    /*

     * We must scan the kex entries to find crypto algorithms and set their

     * appropriate structure

     */

    /* out */

    method = session->next_crypto->kex_methods[SSH_CRYPT_S_C];

    for (i = 0; ssh_ciphertab[i].name != NULL; i++) {

        cmp = strcmp(method, ssh_ciphertab[i].name);

        if (cmp == 0) {

          break;

        }

    }

    if (ssh_ciphertab[i].name == NULL) {

        ssh_set_error(session,SSH_FATAL,"crypt_set_algorithms_server : "

                "no crypto algorithm function found for %s",method);

        return SSH_ERROR;

    }

    SSH_LOG(SSH_LOG_PACKET,"Set output algorithm %s",method);

    session->next_crypto->out_cipher = cipher_new(i);

    if (session->next_crypto->out_cipher == NULL) {

        ssh_set_error_oom(session);

        return SSH_ERROR;

    }

    if (session->next_crypto->out_cipher->aead_encrypt != NULL){

        /* this cipher has integrated MAC */

        if (session->next_crypto->out_cipher->ciphertype == SSH_AEAD_CHACHA20_POLY1305) {

            method = "aead-poly1305";

        } else {

            method = "aead-gcm";

        }

    } else {

        /* we must scan the kex entries to find hmac algorithms and set their appropriate structure */

        /* out */

        method = session->next_crypto->kex_methods[SSH_MAC_S_C];

    }

    /* HMAC algorithm selection */

    for (i = 0; ssh_hmactab[i].name != NULL; i++) {

        cmp = strcmp(method, ssh_hmactab[i].name);

        if (cmp == 0) {

            break;

        }

    }

    if (ssh_hmactab[i].name == NULL) {

      ssh_set_error(session, SSH_FATAL,

          "crypt_set_algorithms_server: no hmac algorithm function found for %s",

          method);

        return SSH_ERROR;

    }

    SSH_LOG(SSH_LOG_PACKET, "Set HMAC output algorithm to %s", method);

    session->next_crypto->out_hmac = ssh_hmactab[i].hmac_type;

    session->next_crypto->out_hmac_etm = ssh_hmactab[i].etm;

    /* in */

    method = session->next_crypto->kex_methods[SSH_CRYPT_C_S];

    for (i = 0; ssh_ciphertab[i].name; i++) {

        cmp = strcmp(method, ssh_ciphertab[i].name);

        if (cmp == 0) {

            break;

        }

    }

    if (ssh_ciphertab[i].name == NULL) {

        ssh_set_error(session,SSH_FATAL,"Crypt_set_algorithms_server :"

                "no crypto algorithm function found for %s",method);

        return SSH_ERROR;

    }

    SSH_LOG(SSH_LOG_PACKET,"Set input algorithm %s",method);

    session->next_crypto->in_cipher = cipher_new(i);

    if (session->next_crypto->in_cipher == NULL) {

        ssh_set_error_oom(session);

        return SSH_ERROR;

    }

    if (session->next_crypto->in_cipher->aead_encrypt != NULL){

        /* this cipher has integrated MAC */

        if (session->next_crypto->in_cipher->ciphertype == SSH_AEAD_CHACHA20_POLY1305) {

            method = "aead-poly1305";

        } else {

            method = "aead-gcm";

        }

    } else {

        /* we must scan the kex entries to find hmac algorithms and set their appropriate structure */

        method = session->next_crypto->kex_methods[SSH_MAC_C_S];

    }

    for (i = 0; ssh_hmactab[i].name != NULL; i++) {

        cmp = strcmp(method, ssh_hmactab[i].name);

        if (cmp == 0) {

            break;

        }

    }

    if (ssh_hmactab[i].name == NULL) {

      ssh_set_error(session, SSH_FATAL,

          "crypt_set_algorithms_server: no hmac algorithm function found for %s",

          method);

        return SSH_ERROR;

    }

    SSH_LOG(SSH_LOG_PACKET, "Set HMAC input algorithm to %s", method);

    session->next_crypto->in_hmac = ssh_hmactab[i].hmac_type;

    session->next_crypto->in_hmac_etm = ssh_hmactab[i].etm;

    /* compression */

    method = session->next_crypto->kex_methods[SSH_COMP_C_S];

    if(strcmp(method,"zlib") == 0){

        SSH_LOG(SSH_LOG_PACKET,"enabling C->S compression");

        session->next_crypto->do_compress_in=1;

    }

    if(strcmp(method,"zlib@openssh.com") == 0){

        SSH_LOG(SSH_LOG_PACKET,"enabling C->S delayed compression");

        if (session->flags & SSH_SESSION_FLAG_AUTHENTICATED) {

            session->next_crypto->do_compress_in = 1;

        } else {

            session->next_crypto->delayed_compress_in = 1;

        }

    }

    method = session->next_crypto->kex_methods[SSH_COMP_S_C];

    if(strcmp(method,"zlib") == 0){

        SSH_LOG(SSH_LOG_PACKET, "enabling S->C compression");

        session->next_crypto->do_compress_out=1;

    }

    if(strcmp(method,"zlib@openssh.com") == 0){

        SSH_LOG(SSH_LOG_PACKET,"enabling S->C delayed compression");

        if (session->flags & SSH_SESSION_FLAG_AUTHENTICATED) {

            session->next_crypto->do_compress_out = 1;

        } else {

            session->next_crypto->delayed_compress_out = 1;

        }

    }

    method = session->next_crypto->kex_methods[SSH_HOSTKEYS];

    session->srv.hostkey = ssh_key_type_from_signature_name(method);

    session->srv.hostkey_digest = ssh_key_hash_from_name(method);

    /* setup DH key exchange type */

    switch (session->next_crypto->kex_type) {

    case SSH_KEX_DH_GROUP1_SHA1:

    case SSH_KEX_DH_GROUP14_SHA1:

    case SSH_KEX_DH_GROUP14_SHA256:

    case SSH_KEX_DH_GROUP16_SHA512:

    case SSH_KEX_DH_GROUP18_SHA512:

      ssh_server_dh_init(session);

      break;

#ifdef WITH_GEX

    case SSH_KEX_DH_GEX_SHA1:

    case SSH_KEX_DH_GEX_SHA256:

      ssh_server_dhgex_init(session);

      break;

#endif /* WITH_GEX */

#ifdef HAVE_ECDH

    case SSH_KEX_ECDH_SHA2_NISTP256:

    case SSH_KEX_ECDH_SHA2_NISTP384:

    case SSH_KEX_ECDH_SHA2_NISTP521:

      ssh_server_ecdh_init(session);

      break;

#endif

#ifdef HAVE_CURVE25519

    case SSH_KEX_CURVE25519_SHA256:

    case SSH_KEX_CURVE25519_SHA256_LIBSSH_ORG:

        ssh_server_curve25519_init(session);

        break;

#endif

    default:

        ssh_set_error(session,

                      SSH_FATAL,

                      "crypt_set_algorithms_server: could not find init "

                      "handler for kex type %d",

                      session->next_crypto->kex_type);

        return SSH_ERROR;

    }

    return SSH_OK;

}

#endif /* WITH_SERVER */