libssh/src/auth.c

/*
 * auth1.c - authentication with SSH protocols
 *
 * This file is part of the SSH Library
 *
 * Copyright (c) 2003-2008 by Aris Adamantiadis
 * Copyright (c) 2008-2009 Andreas Schneider <mail@cynapses.org>
 *
 * 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.
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#ifndef _WIN32
#include <arpa/inet.h>
#endif

#include "libssh/priv.h"
#include "libssh/ssh2.h"
#include "libssh/buffer.h"
#include "libssh/agent.h"
#include "libssh/keyfiles.h"
#include "libssh/misc.h"
#include "libssh/packet.h"
#include "libssh/session.h"
#include "libssh/keys.h"
#include "libssh/auth.h"

/**
 * @defgroup libssh_auth The SSH authentication functions.
 * @ingroup libssh
 *
 * Functions to authenticate with a server.
 *
 * @{
 */

/**
 * @internal
 *
 * @brief Ask access to the ssh-userauth service.
 *
 * @param[in] session   The SSH session handle.
 *
 * @returns SSH_OK on success, SSH_ERROR on error.
 *
 * @bug current implementation is blocking
 */
static int ask_userauth(ssh_session session) {
  int rc = 0;

  enter_function();
  do {
  	rc=ssh_service_request(session,"ssh-userauth");
  	if(rc==SSH_AGAIN)
  		ssh_handle_packets(session,-1);
  } while(rc==SSH_AGAIN);
  leave_function();
  return rc;
}

/**
 * @internal
 *
 * @brief Handles a SSH_USERAUTH_BANNER packet.
 *
 * This banner should be shown to user prior to authentication
 */
SSH_PACKET_CALLBACK(ssh_packet_userauth_banner){
  ssh_string banner;
  (void)type;
  (void)user;
  enter_function();
  banner = buffer_get_ssh_string(packet);
  if (banner == NULL) {
    ssh_log(session, SSH_LOG_RARE,
        "Invalid SSH_USERAUTH_BANNER packet");
  } else {
    ssh_log(session, SSH_LOG_PACKET,
        "Received SSH_USERAUTH_BANNER packet");
    if(session->banner != NULL)
      ssh_string_free(session->banner);
    session->banner = banner;
  }
  leave_function();
  return SSH_PACKET_USED;
}

/**
 * @internal
 *
 * @brief Handles a SSH_USERAUTH_FAILURE packet.
 *
 * This handles the complete or partial authentication failure.
 */
SSH_PACKET_CALLBACK(ssh_packet_userauth_failure){
  char *auth_methods = NULL;
  ssh_string auth;
  uint8_t partial = 0;
  (void) type;
  (void) user;
  enter_function();

  auth = buffer_get_ssh_string(packet);
  if (auth == NULL || buffer_get_u8(packet, &partial) != 1) {
    ssh_set_error(session, SSH_FATAL,
        "Invalid SSH_MSG_USERAUTH_FAILURE message");
    session->auth_state=SSH_AUTH_STATE_ERROR;
    goto end;
  }

  auth_methods = ssh_string_to_char(auth);
  if (auth_methods == NULL) {
    ssh_set_error_oom(session);
    goto end;
  }

  if (partial) {
    session->auth_state=SSH_AUTH_STATE_PARTIAL;
    ssh_log(session,SSH_LOG_PROTOCOL,
        "Partial success. Authentication that can continue: %s",
        auth_methods);
  } else {
    session->auth_state=SSH_AUTH_STATE_FAILED;
    ssh_log(session, SSH_LOG_PROTOCOL,
        "Access denied. Authentication that can continue: %s",
        auth_methods);
    ssh_set_error(session, SSH_REQUEST_DENIED,
            "Access denied. Authentication that can continue: %s",
            auth_methods);

    session->auth_methods = 0;
  }
  if (strstr(auth_methods, "password") != NULL) {
    session->auth_methods |= SSH_AUTH_METHOD_PASSWORD;
  }
  if (strstr(auth_methods, "keyboard-interactive") != NULL) {
    session->auth_methods |= SSH_AUTH_METHOD_INTERACTIVE;
  }
  if (strstr(auth_methods, "publickey") != NULL) {
    session->auth_methods |= SSH_AUTH_METHOD_PUBLICKEY;
  }
  if (strstr(auth_methods, "hostbased") != NULL) {
    session->auth_methods |= SSH_AUTH_METHOD_HOSTBASED;
  }

end:
  ssh_string_free(auth);
  SAFE_FREE(auth_methods);
  leave_function();
  return SSH_PACKET_USED;
}

/**
 * @internal
 *
 * @brief Handles a SSH_USERAUTH_SUCCESS packet.
 *
 * It is also used to communicate the new to the upper levels.
 */
SSH_PACKET_CALLBACK(ssh_packet_userauth_success){
  enter_function();
  (void)packet;
  (void)type;
  (void)user;
  ssh_log(session,SSH_LOG_PACKET,"Received SSH_USERAUTH_SUCCESS");
  ssh_log(session,SSH_LOG_PROTOCOL,"Authentication successful");
  session->auth_state=SSH_AUTH_STATE_SUCCESS;
  session->session_state=SSH_SESSION_STATE_AUTHENTICATED;
  leave_function();
  return SSH_PACKET_USED;
}

/**
 * @internal
 *
 * @brief Handles a SSH_USERAUTH_PK_OK or SSH_USERAUTH_INFO_REQUEST packet.
 *
 * Since the two types of packets share the same code, additional work is done
 * to understand if we are in a public key or keyboard-interactive context.
 */
SSH_PACKET_CALLBACK(ssh_packet_userauth_pk_ok){
	int rc;
	enter_function();
  ssh_log(session,SSH_LOG_PACKET,"Received SSH_USERAUTH_PK_OK/INFO_REQUEST");
  if(session->auth_state==SSH_AUTH_STATE_KBDINT_SENT){
    /* Assuming we are in keyboard-interactive context */
    ssh_log(session,SSH_LOG_PACKET,"keyboard-interactive context, assuming SSH_USERAUTH_INFO_REQUEST");
    rc=ssh_packet_userauth_info_request(session,type,packet,user);
  } else {
    session->auth_state=SSH_AUTH_STATE_PK_OK;
    ssh_log(session,SSH_LOG_PACKET,"assuming SSH_USERAUTH_PK_OK");
    rc=SSH_PACKET_USED;
  }
  leave_function();
  return rc;
}

static int wait_auth_status(ssh_session session) {
  int rc = SSH_AUTH_ERROR;

  enter_function();

  while (session->auth_state == SSH_AUTH_STATE_NONE ||
  		session->auth_state == SSH_AUTH_STATE_KBDINT_SENT) {
    if (ssh_handle_packets(session,-1) != SSH_OK)
      break;
  }
  switch(session->auth_state){
    case SSH_AUTH_STATE_ERROR:
      rc=SSH_AUTH_ERROR;
      break;
    case SSH_AUTH_STATE_FAILED:
      rc=SSH_AUTH_DENIED;
      break;
    case SSH_AUTH_STATE_INFO:
      rc=SSH_AUTH_INFO;
      break;
    case SSH_AUTH_STATE_PARTIAL:
      rc=SSH_AUTH_PARTIAL;
      break;
    case SSH_AUTH_STATE_PK_OK:
    case SSH_AUTH_STATE_SUCCESS:
      rc=SSH_AUTH_SUCCESS;
      break;
    case SSH_AUTH_STATE_KBDINT_SENT:
    case SSH_AUTH_STATE_NONE:
      /* not reached */
      rc=SSH_AUTH_ERROR;
      break;
  }
  leave_function();
  return rc;
}

/**
 * @brief retrieves available authentication methods for this session
 * @deprecated
 * @see ssh_userauth_list
 */
int ssh_auth_list(ssh_session session) {
  return ssh_userauth_list(session, NULL);
}

/**
 * @brief retrieves available authentication methods for this session
 * @param[in] session the SSH session
 * @param[in] username set to NULL
 * @returns A bitfield of values SSH_AUTH_METHOD_NONE, SSH_AUTH_METHOD_PASSWORD,
            SSH_AUTH_METHOD_PUBLICKEY, SSH_AUTH_METHOD_HOSTBASED,
            SSH_AUTH_METHOD_INTERACTIVE.
   @warning Other reserved flags may appear in future versions.
 */
int ssh_userauth_list(ssh_session session, const char *username) {
  if (session == NULL) {
    return SSH_AUTH_ERROR;
  }

#ifdef WITH_SSH1
  if(session->version==1){
    return SSH_AUTH_METHOD_PASSWORD;
  }
#endif
  if (session->auth_methods == 0) {
    ssh_userauth_none(session, username);
  }
  return session->auth_methods;
}

/* use the "none" authentication question */

/**
 * @brief Try to authenticate through the "none" method.
 *
 * @param[in] session   The ssh session to use.
 *
 * @param[in] username  Deprecated, set to NULL.
 *
 * @returns SSH_AUTH_ERROR:   A serious error happened.\n
 *          SSH_AUTH_DENIED:  Authentication failed: use another method\n
 *          SSH_AUTH_PARTIAL: You've been partially authenticated, you still
 *                            have to use another method\n
 *          SSH_AUTH_SUCCESS: Authentication success
 */
int ssh_userauth_none(ssh_session session, const char *username) {
  ssh_string user = NULL;
  ssh_string service = NULL;
  ssh_string method = NULL;
  int rc = SSH_AUTH_ERROR;

  enter_function();

#ifdef WITH_SSH1
  if (session->version == 1) {
    rc = ssh_userauth1_none(session, username);
    leave_function();
    return rc;
  }
#endif
  if(session->auth_methods != 0){
    /* userauth_none or other method was already tried before */
    ssh_set_error(session,SSH_REQUEST_DENIED,"None method rejected by server");
    leave_function();
    return SSH_AUTH_DENIED;
  }
  if (username == NULL) {
    if (session->username == NULL) {
      if (ssh_options_apply(session) < 0) {
        leave_function();
        return rc;
      }
    }
    user = ssh_string_from_char(session->username);
  } else {
    user = ssh_string_from_char(username);
  }

  if (user == NULL) {
    leave_function();
    return rc;
  }

  if (ask_userauth(session) < 0) {
    ssh_string_free(user);
    leave_function();
    return rc;
  }

  method = ssh_string_from_char("none");
  if (method == NULL) {
    goto error;
  }
  service = ssh_string_from_char("ssh-connection");
  if (service == NULL) {
    goto error;
  }

  if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_REQUEST) < 0 ||
      buffer_add_ssh_string(session->out_buffer, user) < 0 ||
      buffer_add_ssh_string(session->out_buffer, service) < 0 ||
      buffer_add_ssh_string(session->out_buffer, method) < 0) {
    goto error;
  }

  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_free(user);
  session->auth_state=SSH_AUTH_STATE_NONE;
  if (packet_send(session) == SSH_ERROR) {
    leave_function();
    return rc;
  }
  rc = wait_auth_status(session);

  leave_function();
  return rc;
error:
  buffer_reinit(session->out_buffer);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_free(user);

  leave_function();
  return rc;
}

/**
 * @brief Try to authenticate through public key.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @param[in]  username The username to authenticate. You can specify NULL if
 *                      ssh_option_set_username() has been used. You cannot try
 *                      two different logins in a row.
 *
 * @param[in]  type     The type of the public key. This value is given by
 *                      publickey_from_file() or ssh_privatekey_type().
 *
 * @param[in]  publickey A public key returned by publickey_from_file().
 *
 * @returns SSH_AUTH_ERROR:   A serious error happened.\n
 *          SSH_AUTH_DENIED:  The server doesn't accept that public key as an
 *                            authentication token. Try another key or another
 *                            method.\n
 *          SSH_AUTH_PARTIAL: You've been partially authenticated, you still
 *                            have to use another method.\n
 *          SSH_AUTH_SUCCESS: The public key is accepted, you want now to use
 *                            ssh_userauth_pubkey().
 *
 * @see publickey_from_file()
 * @see privatekey_from_file()
 * @see ssh_privatekey_type()
 * @see ssh_userauth_pubkey()
 */
int ssh_userauth_offer_pubkey(ssh_session session, const char *username,
    int type, ssh_string publickey) {
  ssh_string user = NULL;
  ssh_string service = NULL;
  ssh_string method = NULL;
  ssh_string algo = NULL;
  int rc = SSH_AUTH_ERROR;

  enter_function();

#ifdef WITH_SSH1
  if (session->version == 1) {
    ssh_userauth1_offer_pubkey(session, username, type, publickey);
    leave_function();
    return rc;
  }
#endif

  if (username == NULL) {
    if (session->username == NULL) {
      if (ssh_options_apply(session) < 0) {
        leave_function();
        return rc;
      }
    }
    user = ssh_string_from_char(session->username);
  } else {
    user = ssh_string_from_char(username);
  }

  if (user == NULL) {
    leave_function();
    return rc;
  }

  if (ask_userauth(session) < 0) {
    ssh_string_free(user);
    leave_function();
    return rc;
  }

  service = ssh_string_from_char("ssh-connection");
  if (service == NULL) {
    goto error;
  }
  method = ssh_string_from_char("publickey");
  if (method == NULL) {
    goto error;
  }
  algo = ssh_string_from_char(ssh_type_to_char(type));
  if (algo == NULL) {
    goto error;
  }

  if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_REQUEST) < 0 ||
      buffer_add_ssh_string(session->out_buffer, user) < 0 ||
      buffer_add_ssh_string(session->out_buffer, service) < 0 ||
      buffer_add_ssh_string(session->out_buffer, method) < 0 ||
      buffer_add_u8(session->out_buffer, 0) < 0 ||
      buffer_add_ssh_string(session->out_buffer, algo) < 0 ||
      buffer_add_ssh_string(session->out_buffer, publickey) < 0) {
    goto error;
  }

  ssh_string_free(user);
  ssh_string_free(method);
  ssh_string_free(service);
  ssh_string_free(algo);
  session->auth_state=SSH_AUTH_STATE_NONE;
  if (packet_send(session) == SSH_ERROR) {
    leave_function();
    return rc;
  }
  rc = wait_auth_status(session);

  leave_function();
  return rc;
error:
  buffer_reinit(session->out_buffer);
  ssh_string_free(user);
  ssh_string_free(method);
  ssh_string_free(service);
  ssh_string_free(algo);

  leave_function();
  return rc;
}


/**
 * @brief Try to authenticate through public key.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @param[in]  username The username to authenticate. You can specify NULL if
 *                      ssh_option_set_username() has been used. You cannot try
 *                      two different logins in a row.
 *
 * @param[in]  publickey A public key returned by publickey_from_file(), or NULL
 *                       to generate automatically from privatekey.
 *
 * @param[in]  privatekey A private key returned by privatekey_from_file().
 *
 * @returns SSH_AUTH_ERROR:   A serious error happened.\n
 *          SSH_AUTH_DENIED:  Authentication failed: use another method.\n
 *          SSH_AUTH_PARTIAL: You've been partially authenticated, you still
 *                            have to use another method.\n
 *          SSH_AUTH_SUCCESS: Authentication successful.
 *
 * @see publickey_from_file()
 * @see privatekey_from_file()
 * @see privatekey_free()
 * @see ssh_userauth_offer_pubkey()
 */
int ssh_userauth_pubkey(ssh_session session, const char *username,
    ssh_string publickey, ssh_private_key privatekey) {
  ssh_string user = NULL;
  ssh_string service = NULL;
  ssh_string method = NULL;
  ssh_string algo = NULL;
  ssh_string sign = NULL;
  ssh_public_key pk = NULL;
  ssh_string pkstr = NULL;
  int rc = SSH_AUTH_ERROR;

  enter_function();

#if 0
  if (session->version == 1) {
    return ssh_userauth1_pubkey(session, username, publickey, privatekey);
  }
#endif

  if (username == NULL) {
    if (session->username == NULL) {
      if (ssh_options_apply(session) < 0) {
        leave_function();
        return rc;
      }
    }
    user = ssh_string_from_char(session->username);
  } else {
    user = ssh_string_from_char(username);
  }

  if (user == NULL) {
    leave_function();
    return rc;
  }

  if (ask_userauth(session) < 0) {
    ssh_string_free(user);
    leave_function();
    return rc;
  }

  service = ssh_string_from_char("ssh-connection");
  if (service == NULL) {
    goto error;
  }
  method = ssh_string_from_char("publickey");
  if (method == NULL) {
    goto error;
  }
  algo = ssh_string_from_char(ssh_type_to_char(privatekey->type));
  if (algo == NULL) {
    goto error;
  }
  if (publickey == NULL) {
    pk = publickey_from_privatekey(privatekey);
    if (pk == NULL) {
      goto error;
    }
    pkstr = publickey_to_string(pk);
    publickey_free(pk);
    if (pkstr == NULL) {
      goto error;
    }
  }

  /* we said previously the public key was accepted */
  if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_REQUEST) < 0 ||
      buffer_add_ssh_string(session->out_buffer, user) < 0 ||
      buffer_add_ssh_string(session->out_buffer, service) < 0 ||
      buffer_add_ssh_string(session->out_buffer, method) < 0 ||
      buffer_add_u8(session->out_buffer, 1) < 0 ||
      buffer_add_ssh_string(session->out_buffer, algo) < 0 ||
      buffer_add_ssh_string(session->out_buffer, (publickey == NULL ? pkstr : publickey)) < 0) {
    goto error;
  }

  ssh_string_free(user);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_free(algo);
  ssh_string_free(pkstr);

  sign = ssh_do_sign(session,session->out_buffer, privatekey);
  if (sign) {
    if (buffer_add_ssh_string(session->out_buffer,sign) < 0) {
      goto error;
    }
    ssh_string_free(sign);
    session->auth_state=SSH_AUTH_STATE_NONE;
    if (packet_send(session) == SSH_ERROR) {
      leave_function();
      return rc;
    }
    rc = wait_auth_status(session);
  }

  leave_function();
  return rc;
error:
  buffer_reinit(session->out_buffer);
  ssh_string_free(user);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_free(algo);
  ssh_string_free(pkstr);

  leave_function();
  return rc;
}

/**
 * @brief Try to authenticate through a private key file.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @param[in]  username The username to authenticate. You can specify NULL if
 *                      ssh_option_set_username() has been used. You cannot try
 *                      two different logins in a row.
 *
 * @param[in] filename  Filename containing the private key.
 *
 * @param[in] passphrase Passphrase to decrypt the private key. Set to null if
 *                       none is needed or it is unknown.
 *
 * @returns SSH_AUTH_ERROR:   A serious error happened.\n
 *          SSH_AUTH_DENIED:  Authentication failed: use another method.\n
 *          SSH_AUTH_PARTIAL: You've been partially authenticated, you still
 *                            have to use another method.\n
 *          SSH_AUTH_SUCCESS: Authentication successful.
 *
 * @see publickey_from_file()
 * @see privatekey_from_file()
 * @see privatekey_free()
 * @see ssh_userauth_pubkey()
 */
int ssh_userauth_privatekey_file(ssh_session session, const char *username,
    const char *filename, const char *passphrase) {
  char *pubkeyfile = NULL;
  ssh_string pubkey = NULL;
  ssh_private_key privkey = NULL;
  int type = 0;
  int rc = SSH_AUTH_ERROR;

  enter_function();

  pubkeyfile = malloc(strlen(filename) + 1 + 4);
  if (pubkeyfile == NULL) {
    leave_function();
    return SSH_AUTH_ERROR;
  }
  sprintf(pubkeyfile, "%s.pub", filename);

  pubkey = publickey_from_file(session, pubkeyfile, &type);
  if (pubkey == NULL) {
    ssh_log(session, SSH_LOG_RARE, "Public key file %s not found. Trying to generate it.", pubkeyfile);
    /* auto-detect the key type with type=0 */
    privkey = privatekey_from_file(session, filename, 0, passphrase);
  } else {
    ssh_log(session, SSH_LOG_RARE, "Public key file %s loaded.", pubkeyfile);
    privkey = privatekey_from_file(session, filename, type, passphrase);
  }
  if (privkey == NULL) {
    goto error;
  }
  /* ssh_userauth_pubkey is responsible for taking care of null-pubkey */
  rc = ssh_userauth_pubkey(session, username, pubkey, privkey);
  privatekey_free(privkey);

error:
  SAFE_FREE(pubkeyfile);
  ssh_string_free(pubkey);

  leave_function();
  return rc;
}

#ifndef _WIN32
/**
 * @brief Try to authenticate through public key with an ssh agent.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @param[in]  username The username to authenticate. You can specify NULL if
 *                      ssh_option_set_username() has been used. You cannot try
 *                      two different logins in a row.
 *
 * @param[in]  publickey The public key provided by the agent.
 *
 * @returns SSH_AUTH_ERROR:   A serious error happened.\n
 *          SSH_AUTH_DENIED:  Authentication failed: use another method.\n
 *          SSH_AUTH_PARTIAL: You've been partially authenticated, you still
 *                            have to use another method.\n
 *          SSH_AUTH_SUCCESS: Authentication successful.
 *
 * @see publickey_from_file()
 * @see privatekey_from_file()
 * @see privatekey_free()
 * @see ssh_userauth_offer_pubkey()
 */
int ssh_userauth_agent_pubkey(ssh_session session, const char *username,
    ssh_public_key publickey) {
  ssh_string user = NULL;
  ssh_string service = NULL;
  ssh_string method = NULL;
  ssh_string algo = NULL;
  ssh_string key = NULL;
  ssh_string sign = NULL;
  int rc = SSH_AUTH_ERROR;

  enter_function();

  if (! agent_is_running(session)) {
    return rc;
  }

  if (username == NULL) {
    if (session->username == NULL) {
      if (ssh_options_apply(session) < 0) {
        leave_function();
        return rc;
      }
    }
    user = ssh_string_from_char(session->username);
  } else {
    user = ssh_string_from_char(username);
  }

  if (user == NULL) {
    leave_function();
    return rc;
  }

  if (ask_userauth(session) < 0) {
    ssh_string_free(user);
    leave_function();
    return rc;
  }

  service = ssh_string_from_char("ssh-connection");
  if (service == NULL) {
    goto error;
  }
  method = ssh_string_from_char("publickey");
  if (method == NULL) {
    goto error;
  }
  algo = ssh_string_from_char(ssh_type_to_char(publickey->type));
  if (algo == NULL) {
    goto error;
  }
  key = publickey_to_string(publickey);
  if (key == NULL) {
    goto error;
  }

  /* we said previously the public key was accepted */
  if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_REQUEST) < 0 ||
      buffer_add_ssh_string(session->out_buffer, user) < 0 ||
      buffer_add_ssh_string(session->out_buffer, service) < 0 ||
      buffer_add_ssh_string(session->out_buffer, method) < 0 ||
      buffer_add_u8(session->out_buffer, 1) < 0 ||
      buffer_add_ssh_string(session->out_buffer, algo) < 0 ||
      buffer_add_ssh_string(session->out_buffer, key) < 0) {
    goto error;
  }

  sign = ssh_do_sign_with_agent(session, session->out_buffer, publickey);

  if (sign) {
    if (buffer_add_ssh_string(session->out_buffer, sign) < 0) {
      goto error;
    }
    ssh_string_free(sign);
    session->auth_state=SSH_AUTH_STATE_NONE;
    if (packet_send(session) == SSH_ERROR) {
      leave_function();
      return rc;
    }
    rc = wait_auth_status(session);
  }

  ssh_string_free(user);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_free(algo);
  ssh_string_free(key);

  leave_function();

  return rc;
error:
  buffer_reinit(session->out_buffer);
  ssh_string_free(sign);
  ssh_string_free(user);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_free(algo);
  ssh_string_free(key);

  leave_function();
  return rc;
}
#endif /* _WIN32 */

/**
 * @brief Try to authenticate by password.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @param[in]  username The username to authenticate. You can specify NULL if
 *                      ssh_option_set_username() has been used. You cannot try
 *                      two different logins in a row.
 *
 * @param[in]  password The password to use. Take care to clean it after
 *                      the authentication.
 *
 * @returns SSH_AUTH_ERROR:   A serious error happened.\n
 *          SSH_AUTH_DENIED:  Authentication failed: use another method.\n
 *          SSH_AUTH_PARTIAL: You've been partially authenticated, you still
 *                            have to use another method.\n
 *          SSH_AUTH_SUCCESS: Authentication successful.
 *
 * @see ssh_userauth_kbdint()
 * @see BURN_STRING
 */
int ssh_userauth_password(ssh_session session, const char *username,
    const char *password) {
  ssh_string user = NULL;
  ssh_string service = NULL;
  ssh_string method = NULL;
  ssh_string pwd = NULL;
  int rc = SSH_AUTH_ERROR;

  enter_function();

#ifdef WITH_SSH1
  if (session->version == 1) {
    rc = ssh_userauth1_password(session, username, password);
    leave_function();
    return rc;
  }
#endif

  if (username == NULL) {
    if (session->username == NULL) {
      if (ssh_options_apply(session) < 0) {
        leave_function();
        return rc;
      }
    }
    user = ssh_string_from_char(session->username);
  } else {
    user = ssh_string_from_char(username);
  }

  if (user == NULL) {
    leave_function();
    return rc;
  }

  if (ask_userauth(session) < 0) {
    ssh_string_free(user);
    leave_function();
    return rc;
  }

  service = ssh_string_from_char("ssh-connection");
  if (service == NULL) {
    goto error;
  }
  method = ssh_string_from_char("password");
  if (method == NULL) {
    goto error;
  }
  pwd = ssh_string_from_char(password);
  if (pwd == NULL) {
    goto error;
  }

  if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_REQUEST) < 0 ||
      buffer_add_ssh_string(session->out_buffer, user) < 0 ||
      buffer_add_ssh_string(session->out_buffer, service) < 0 ||
      buffer_add_ssh_string(session->out_buffer, method) < 0 ||
      buffer_add_u8(session->out_buffer, 0) < 0 ||
      buffer_add_ssh_string(session->out_buffer, pwd) < 0) {
    goto error;
  }

  ssh_string_free(user);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_burn(pwd);
  ssh_string_free(pwd);
  session->auth_state=SSH_AUTH_STATE_NONE;
  if (packet_send(session) == SSH_ERROR) {
    leave_function();
    return rc;
  }
  rc = wait_auth_status(session);

  leave_function();
  return rc;
error:
  buffer_reinit(session->out_buffer);
  ssh_string_free(user);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_burn(pwd);
  ssh_string_free(pwd);

  leave_function();
  return rc;
}

/**
 * @brief Tries to automatically authenticate with public key and "none"
 *
 * It may fail, for instance it doesn't ask for a password and uses a default
 * asker for passphrases (in case the private key is encrypted).
 *
 * @param[in]  session  The ssh session to authenticate with.
 *
 * @param[in]  passphrase Use this passphrase to unlock the privatekey. Use NULL
 *                        if you don't want to use a passphrase or the user
 *                        should be asked.
 *
 * @returns SSH_AUTH_ERROR:   A serious error happened\n
 *          SSH_AUTH_DENIED:  Authentication failed: use another method\n
 *          SSH_AUTH_PARTIAL: You've been partially authenticated, you still
 *                            have to use another method\n
 *          SSH_AUTH_SUCCESS: Authentication success
 *
 * @see ssh_userauth_kbdint()
 * @see ssh_userauth_password()
 */
int ssh_userauth_autopubkey(ssh_session session, const char *passphrase) {
  struct ssh_iterator *it;
  ssh_private_key privkey;
  ssh_public_key pubkey;
  ssh_string pubkey_string;
  int type = 0;
  int rc;

  enter_function();

  /* Always test none authentication */
  rc = ssh_userauth_none(session, NULL);
  if (rc == SSH_AUTH_ERROR || rc == SSH_AUTH_SUCCESS) {
    leave_function();
    return rc;
  }

  /* Try authentication with ssh-agent first */
#ifndef _WIN32
  if (agent_is_running(session)) {
    char *privkey_file = NULL;

    ssh_log(session, SSH_LOG_RARE,
        "Trying to authenticate with SSH agent keys as user: %s",
        session->username);

    for (pubkey = agent_get_first_ident(session, &privkey_file);
        pubkey != NULL;
        pubkey = agent_get_next_ident(session, &privkey_file)) {

      ssh_log(session, SSH_LOG_RARE, "Trying identity %s", privkey_file);

      pubkey_string = publickey_to_string(pubkey);
      if (pubkey_string) {
        rc = ssh_userauth_offer_pubkey(session, NULL, pubkey->type, pubkey_string);
        ssh_string_free(pubkey_string);
        if (rc == SSH_AUTH_ERROR) {
          SAFE_FREE(privkey_file);
          publickey_free(pubkey);
          leave_function();

          return rc;
        } else if (rc != SSH_AUTH_SUCCESS) {
          ssh_log(session, SSH_LOG_PROTOCOL, "Public key refused by server");
          SAFE_FREE(privkey_file);
          publickey_free(pubkey);
          continue;
        }
        ssh_log(session, SSH_LOG_PROTOCOL, "Public key accepted");
        /* pubkey accepted by server ! */
        rc = ssh_userauth_agent_pubkey(session, NULL, pubkey);
        if (rc == SSH_AUTH_ERROR) {
          SAFE_FREE(privkey_file);
          publickey_free(pubkey);
          leave_function();

          return rc;
        } else if (rc != SSH_AUTH_SUCCESS) {
          ssh_log(session, SSH_LOG_RARE,
              "Server accepted public key but refused the signature ;"
              " It might be a bug of libssh");
          SAFE_FREE(privkey_file);
          publickey_free(pubkey);
          continue;
        }
        /* auth success */
        ssh_log(session, SSH_LOG_PROTOCOL, "Authentication using %s success",
            privkey_file);
        SAFE_FREE(privkey_file);
        publickey_free(pubkey);

        leave_function();

        return SSH_AUTH_SUCCESS;
      } /* if pubkey */
      SAFE_FREE(privkey_file);
      publickey_free(pubkey);
    } /* for each privkey */
  } /* if agent is running */
#endif


  for (it = ssh_list_get_iterator(session->identity);
       it != NULL;
       it = it->next) {
    const char *privkey_file = it->data;
    int privkey_open = 0;

    privkey = NULL;

    ssh_log(session, SSH_LOG_PROTOCOL, "Trying to read privatekey %s", privkey_file);

    rc = ssh_try_publickey_from_file(session, privkey_file, &pubkey_string, &type);
    if (rc == 1) {
      char *publickey_file;
      size_t len;

      privkey = privatekey_from_file(session, privkey_file, type, passphrase);
      if (privkey == NULL) {
        ssh_log(session, SSH_LOG_RARE,
          "Reading private key %s failed (bad passphrase ?)",
          privkey_file);
        leave_function();
        return SSH_AUTH_ERROR;
      }
      privkey_open = 1;

      pubkey = publickey_from_privatekey(privkey);
      if (pubkey == NULL) {
        privatekey_free(privkey);
        ssh_set_error_oom(session);
        leave_function();
        return SSH_AUTH_ERROR;
      }

      pubkey_string = publickey_to_string(pubkey);
      type = pubkey->type;
      publickey_free(pubkey);
      if (pubkey_string == NULL) {
        ssh_set_error_oom(session);
        leave_function();
        return SSH_AUTH_ERROR;
      }

      len = strlen(privkey_file) + 5;
      publickey_file = malloc(len);
      if (publickey_file == NULL) {
        ssh_set_error_oom(session);
        leave_function();
        return SSH_AUTH_ERROR;
      }
      snprintf(publickey_file, len, "%s.pub", privkey_file);
      rc = ssh_publickey_to_file(session, publickey_file, pubkey_string, type);
      if (rc < 0) {
        ssh_log(session, SSH_LOG_PACKET,
            "Could not write public key to file: %s", publickey_file);
      }
      SAFE_FREE(publickey_file);
    } else if (rc < 0) {
      continue;
    }

    rc = ssh_userauth_offer_pubkey(session, NULL, type, pubkey_string);
    if (rc == SSH_AUTH_ERROR){
      ssh_string_free(pubkey_string);
      ssh_log(session, SSH_LOG_RARE, "Publickey authentication error");
      leave_function();
      return rc;
    } else {
      if (rc != SSH_AUTH_SUCCESS){
        ssh_log(session, SSH_LOG_PROTOCOL, "Publickey refused by server");
        ssh_string_free(pubkey_string);
        continue;
      }
    }

    /* Public key accepted by server! */
    if (!privkey_open) {
      ssh_log(session, SSH_LOG_PROTOCOL, "Trying to read privatekey %s",
          privkey_file);
      privkey = privatekey_from_file(session, privkey_file, type, passphrase);
      if (privkey == NULL) {
        ssh_log(session, SSH_LOG_RARE,
            "Reading private key %s failed (bad passphrase ?)",
            privkey_file);
        ssh_string_free(pubkey_string);
        continue; /* continue the loop with other pubkey */
      }
    }

    rc = ssh_userauth_pubkey(session, NULL, pubkey_string, privkey);
    if (rc == SSH_AUTH_ERROR) {
      ssh_string_free(pubkey_string);
      privatekey_free(privkey);
      leave_function();
      return rc;
    } else {
      if (rc != SSH_AUTH_SUCCESS){
        ssh_log(session, SSH_LOG_RARE,
            "The server accepted the public key but refused the signature");
        ssh_string_free(pubkey_string);
        privatekey_free(privkey);
        continue;
      }
    }

    /* auth success */
    ssh_log(session, SSH_LOG_PROTOCOL,
        "Successfully authenticated using %s", privkey_file);
    ssh_string_free(pubkey_string);
    privatekey_free(privkey);

    leave_function();
    return SSH_AUTH_SUCCESS;
  }

  /* at this point, pubkey is NULL and so is privkeyfile */
  ssh_log(session, SSH_LOG_PROTOCOL,
      "Tried every public key, none matched");
  ssh_set_error(session,SSH_NO_ERROR,"No public key matched");

  leave_function();
  return SSH_AUTH_DENIED;
}

struct ssh_kbdint_struct {
    uint32_t nprompts;
    char *name;
    char *instruction;
    char **prompts;
    unsigned char *echo; /* bool array */
    char **answers;
};

static ssh_kbdint kbdint_new(void) {
  ssh_kbdint kbd;

  kbd = malloc(sizeof (struct ssh_kbdint_struct));
  if (kbd == NULL) {
    return NULL;
  }
  ZERO_STRUCTP(kbd);

  return kbd;
}


static void kbdint_free(ssh_kbdint kbd) {
  int i, n;

  if (kbd == NULL) {
    return;
  }

  n = kbd->nprompts;

  SAFE_FREE(kbd->name);
  SAFE_FREE(kbd->instruction);
  SAFE_FREE(kbd->echo);

  if (kbd->prompts) {
    for (i = 0; i < n; i++) {
      BURN_STRING(kbd->prompts[i]);
      SAFE_FREE(kbd->prompts[i]);
    }
    SAFE_FREE(kbd->prompts);
  }
  if (kbd->answers) {
    for (i = 0; i < n; i++) {
      BURN_STRING(kbd->answers[i]);
      SAFE_FREE(kbd->answers[i]);
    }
    SAFE_FREE(kbd->answers);
  }

  SAFE_FREE(kbd);
}

static void kbdint_clean(ssh_kbdint kbd) {
  int i, n;

  if (kbd == NULL) {
    return;
  }

  n = kbd->nprompts;

  SAFE_FREE(kbd->name);
  SAFE_FREE(kbd->instruction);
  SAFE_FREE(kbd->echo);

  if (kbd->prompts) {
    for (i = 0; i < n; i++) {
      BURN_STRING(kbd->prompts[i]);
      SAFE_FREE(kbd->prompts[i]);
    }
    SAFE_FREE(kbd->prompts);
  }

  if (kbd->answers) {
    for (i = 0; i < n; i++) {
      BURN_STRING(kbd->answers[i]);
      SAFE_FREE(kbd->answers[i]);
    }
      SAFE_FREE(kbd->answers);
  }

  kbd->nprompts = 0;
}

/* this function sends the first packet as explained in section 3.1
 * of the draft */
static int kbdauth_init(ssh_session session, const char *user,
    const char *submethods) {
  ssh_string usr = NULL;
  ssh_string sub = NULL;
  ssh_string service = NULL;
  ssh_string method = NULL;
  int rc = SSH_AUTH_ERROR;

  enter_function();

  usr = ssh_string_from_char(user);
  if (usr == NULL) {
    goto error;
  }
  sub = (submethods ? ssh_string_from_char(submethods) : ssh_string_from_char(""));
  if (sub == NULL) {
    goto error;
  }
  service = ssh_string_from_char("ssh-connection");
  if (service == NULL) {
    goto error;
  }
  method = ssh_string_from_char("keyboard-interactive");
  if (method == NULL) {
    goto error;
  }

  if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_REQUEST) < 0 ||
      buffer_add_ssh_string(session->out_buffer, usr) < 0 ||
      buffer_add_ssh_string(session->out_buffer, service) < 0 ||
      buffer_add_ssh_string(session->out_buffer, method) < 0 ||
      buffer_add_u32(session->out_buffer, 0) < 0 ||
      buffer_add_ssh_string(session->out_buffer, sub) < 0) {
    goto error;
  }

  ssh_string_free(usr);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_free(sub);
  session->auth_state=SSH_AUTH_STATE_KBDINT_SENT;
  if (packet_send(session) == SSH_ERROR) {
    leave_function();
    return rc;
  }
  rc = wait_auth_status(session);

  leave_function();
  return rc;
error:
  buffer_reinit(session->out_buffer);
  ssh_string_free(usr);
  ssh_string_free(service);
  ssh_string_free(method);
  ssh_string_free(sub);

  leave_function();
  return rc;
}

/**
 * @internal
 * @brief handles a SSH_USERAUTH_INFO_REQUEST packet, as used in
 *        keyboard-interactive authentication, and changes the
 *        authentication state.
 */
SSH_PACKET_CALLBACK(ssh_packet_userauth_info_request) {
  ssh_string name; /* name of the "asking" window showed to client */
  ssh_string instruction;
  ssh_string tmp;
  uint32_t nprompts;
  uint32_t i;
  (void)user;
  (void)type;
  enter_function();

  name = buffer_get_ssh_string(packet);
  instruction = buffer_get_ssh_string(packet);
  tmp = buffer_get_ssh_string(packet);
  buffer_get_u32(packet, &nprompts);

  if (name == NULL || instruction == NULL || tmp == NULL) {
    ssh_string_free(name);
    ssh_string_free(instruction);
    /* tmp if empty if we got here */
    ssh_set_error(session, SSH_FATAL, "Invalid USERAUTH_INFO_REQUEST msg");
    leave_function();
    return SSH_PACKET_USED;
  }
  ssh_string_free(tmp);

  if (session->kbdint == NULL) {
    session->kbdint = kbdint_new();
    if (session->kbdint == NULL) {
      ssh_set_error_oom(session);
      ssh_string_free(name);
      ssh_string_free(instruction);

      leave_function();
      return SSH_PACKET_USED;
    }
  } else {
    kbdint_clean(session->kbdint);
  }

  session->kbdint->name = ssh_string_to_char(name);
  ssh_string_free(name);
  if (session->kbdint->name == NULL) {
    ssh_set_error_oom(session);
    kbdint_free(session->kbdint);
    leave_function();
    return SSH_PACKET_USED;
  }

  session->kbdint->instruction = ssh_string_to_char(instruction);
  ssh_string_free(instruction);
  if (session->kbdint->instruction == NULL) {
    ssh_set_error_oom(session);
    kbdint_free(session->kbdint);
    session->kbdint = NULL;
    leave_function();
    return SSH_PACKET_USED;
  }

  nprompts = ntohl(nprompts);
  ssh_log(session,SSH_LOG_PACKET,"kbdint: %d prompts",nprompts);
  if (nprompts > KBDINT_MAX_PROMPT) {
    ssh_set_error(session, SSH_FATAL,
        "Too much prompt asked from server: %u (0x%.4x)",
        nprompts, nprompts);
    kbdint_free(session->kbdint);
    session->kbdint = NULL;
    leave_function();
    return SSH_PACKET_USED;
  }

  session->kbdint->nprompts = nprompts;
  session->kbdint->prompts = malloc(nprompts * sizeof(char *));
  if (session->kbdint->prompts == NULL) {
    session->kbdint->nprompts = 0;
    ssh_set_error_oom(session);
    kbdint_free(session->kbdint);
    session->kbdint = NULL;
    leave_function();
    return SSH_PACKET_USED;
  }
  memset(session->kbdint->prompts, 0, nprompts * sizeof(char *));

  session->kbdint->echo = malloc(nprompts);
  if (session->kbdint->echo == NULL) {
    session->kbdint->nprompts = 0;
    ssh_set_error_oom(session);
    kbdint_free(session->kbdint);
    session->kbdint = NULL;
    leave_function();
    return SSH_PACKET_USED;
  }
  memset(session->kbdint->echo, 0, nprompts);

  for (i = 0; i < nprompts; i++) {
    tmp = buffer_get_ssh_string(packet);
    buffer_get_u8(packet, &session->kbdint->echo[i]);
    if (tmp == NULL) {
      ssh_set_error(session, SSH_FATAL, "Short INFO_REQUEST packet");
      kbdint_free(session->kbdint);
      session->kbdint = NULL;
      leave_function();
      return SSH_PACKET_USED;
    }
    session->kbdint->prompts[i] = ssh_string_to_char(tmp);
    ssh_string_free(tmp);
    if (session->kbdint->prompts[i] == NULL) {
      ssh_set_error_oom(session);
      kbdint_free(session->kbdint);
      session->kbdint = NULL;
      leave_function();
      return SSH_PACKET_USED;
    }
  }
  session->auth_state=SSH_AUTH_STATE_INFO;
  leave_function();
  return SSH_PACKET_USED;
}

/**
 * @internal
 * @brief Sends the current challenge response and wait for a
 * reply from the server
 * @returns SSH_AUTH_INFO if more info is needed
 * @returns SSH_AUTH_SUCCESS
 * @returns SSH_AUTH_FAILURE
 * @returns SSH_AUTH_PARTIAL
 */
static int kbdauth_send(ssh_session session) {
  ssh_string answer = NULL;
  int rc = SSH_AUTH_ERROR;
  uint32_t i;

  enter_function();

  if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_INFO_RESPONSE) < 0 ||
      buffer_add_u32(session->out_buffer,
        htonl(session->kbdint->nprompts)) < 0) {
    goto error;
  }

  for (i = 0; i < session->kbdint->nprompts; i++) {
    if (session->kbdint->answers[i]) {
      answer = ssh_string_from_char(session->kbdint->answers[i]);
    } else {
      answer = ssh_string_from_char("");
    }
    if (answer == NULL) {
      goto error;
    }

    if (buffer_add_ssh_string(session->out_buffer, answer) < 0) {
      goto error;
    }

    ssh_string_burn(answer);
    ssh_string_free(answer);
  }
  session->auth_state=SSH_AUTH_STATE_KBDINT_SENT;
  kbdint_free(session->kbdint);
  session->kbdint = NULL;
  if (packet_send(session) == SSH_ERROR) {
    leave_function();
    return rc;
  }
  rc = wait_auth_status(session);

  leave_function();
  return rc;
error:
  buffer_reinit(session->out_buffer);
  ssh_string_burn(answer);
  ssh_string_free(answer);

  leave_function();
  return rc;
}

/**
 * @brief Try to authenticate through the "keyboard-interactive" method.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @param[in]  user     The username to authenticate. You can specify NULL if
 *                      ssh_option_set_username() has been used. You cannot try
 *                      two different logins in a row.
 *
 * @param[in]  submethods Undocumented. Set it to NULL.
 *
 * @returns SSH_AUTH_ERROR:   A serious error happened\n
 *          SSH_AUTH_DENIED:  Authentication failed : use another method\n
 *          SSH_AUTH_PARTIAL: You've been partially authenticated, you still
 *                            have to use another method\n
 *          SSH_AUTH_SUCCESS: Authentication success\n
 *          SSH_AUTH_INFO:    The server asked some questions. Use
 *                            ssh_userauth_kbdint_getnprompts() and such.
 *
 * @see ssh_userauth_kbdint_getnprompts()
 * @see ssh_userauth_kbdint_getname()
 * @see ssh_userauth_kbdint_getinstruction()
 * @see ssh_userauth_kbdint_getprompt()
 * @see ssh_userauth_kbdint_setanswer()
 */
int ssh_userauth_kbdint(ssh_session session, const char *user,
    const char *submethods) {
  int rc = SSH_AUTH_ERROR;

  if (session->version == 1) {
    /* No keyb-interactive for ssh1 */
    return SSH_AUTH_DENIED;
  }

  enter_function();

  if (session->kbdint == NULL) {
    /* first time we call. we must ask for a challenge */
    if (user == NULL) {
      if ((user = session->username) == NULL) {
        if (ssh_options_apply(session) < 0) {
          leave_function();
          return SSH_AUTH_ERROR;
        } else {
          user = session->username;
        }
      }
    }

    if (ask_userauth(session)) {
      leave_function();
      return SSH_AUTH_ERROR;
    }

    rc = kbdauth_init(session, user, submethods);

    leave_function();
    return rc;
  }

  /*
   * If we are at this point, it is because session->kbdint exists.
   * It means the user has set some information there we need to send
   * the server and then we need to ack the status (new questions or ok
   * pass in).
   */
  rc = kbdauth_send(session);

  leave_function();
  return rc;
}

/**
 * @brief Get the number of prompts (questions) the server has given.
 *
 * You have called ssh_userauth_kbdint() and got SSH_AUTH_INFO. This
 * function returns the questions from the server.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @returns             The number of prompts.
 */
int ssh_userauth_kbdint_getnprompts(ssh_session session) {
  return session->kbdint->nprompts;
}

/**
 * @brief Get the "name" of the message block.
 *
 * You have called ssh_userauth_kbdint() and got SSH_AUTH_INFO. This
 * function returns the questions from the server.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @returns             The name of the message block. Do not free it.
 */
const char *ssh_userauth_kbdint_getname(ssh_session session) {
  return session->kbdint->name;
}

/**
 * @brief Get the "instruction" of the message block.
 *
 * You have called ssh_userauth_kbdint() and got SSH_AUTH_INFO. This
 * function returns the questions from the server.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @returns             The instruction of the message block.
 */

const char *ssh_userauth_kbdint_getinstruction(ssh_session session) {
  return session->kbdint->instruction;
}

/**
 * @brief Get a prompt from a message block.
 *
 * You have called ssh_userauth_kbdint() and got SSH_AUTH_INFO. This
 * function returns the questions from the server.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @param[in]  i        The index number of the i'th prompt.
 *
 * @param[in]  echo     When different of NULL, it will obtain a boolean meaning
 *                      that the resulting user input should be echoed or not
 *                      (like passwords).
 *
 * @returns             A pointer to the prompt. Do not free it.
 */
const char *ssh_userauth_kbdint_getprompt(ssh_session session, unsigned int i,
    char *echo) {
  if (i > session->kbdint->nprompts) {
    return NULL;
  }

  if (echo) {
    *echo = session->kbdint->echo[i];
  }

  return session->kbdint->prompts[i];
}

/**
 * @brief Set the answer for a question from a message block.
 *
 * If you have called ssh_userauth_kbdint() and got SSH_AUTH_INFO, this
 * function returns the questions from the server.
 *
 * @param[in]  session  The ssh session to use.
 *
 * @param[in]  i index  The number of the ith prompt.
 *
 * @param[in]  answer   The answer to give to the server.
 *
 * @return              0 on success, < 0 on error.
 */
int ssh_userauth_kbdint_setanswer(ssh_session session, unsigned int i,
    const char *answer) {
  if (session == NULL || answer == NULL || i > session->kbdint->nprompts) {
    return -1;
  }

  if (session->kbdint->answers == NULL) {
    session->kbdint->answers = malloc(sizeof(char*) * session->kbdint->nprompts);
    if (session->kbdint->answers == NULL) {
      return -1;
    }
    memset(session->kbdint->answers, 0, sizeof(char *) * session->kbdint->nprompts);
  }

  if (session->kbdint->answers[i]) {
    BURN_STRING(session->kbdint->answers[i]);
    SAFE_FREE(session->kbdint->answers[i]);
  }

  session->kbdint->answers[i] = strdup(answer);
  if (session->kbdint->answers[i] == NULL) {
    return -1;
  }

  return 0;
}

/** @} */

/* vim: set ts=4 sw=4 et cindent: */