cli-authinteract.c

/*
 * Dropbear SSH
 * 
 * Copyright (c) 2005 Matt Johnston
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. */

#include "includes.h"
#include "buffer.h"
#include "dbutil.h"
#include "session.h"
#include "ssh.h"
#include "runopts.h"

#ifdef ENABLE_CLI_INTERACT_AUTH

static unsigned char* get_response(unsigned char* prompt)
{
      FILE* tty = NULL;
      unsigned char* response = NULL;
      /* not a password, but a reasonable limit */
      char buf[DROPBEAR_MAX_CLI_PASS];
      char* ret = NULL;

      fprintf(stderr, "%s", prompt);

      tty = fopen(_PATH_TTY, "r");
      if (tty) {
            ret = fgets(buf, sizeof(buf), tty);
            fclose(tty);
      } else {
            ret = fgets(buf, sizeof(buf), stdin);
      }

      if (ret == NULL) {
            response = (unsigned char*)m_strdup("");
      } else {
            unsigned int buflen = strlen(buf);
            /* fgets includes newlines */
            if (buflen > 0 && buf[buflen-1] == '\n')
                  buf[buflen-1] = '\0';
            response = (unsigned char*)m_strdup(buf);
      }

      m_burn(buf, sizeof(buf));

      return response;
}

void recv_msg_userauth_info_request() {

      unsigned char *name = NULL;
      unsigned char *instruction = NULL;
      unsigned int num_prompts = 0;
      unsigned int i;

      unsigned char *prompt = NULL;
      unsigned int echo = 0;
      unsigned char *response = NULL;

      TRACE(("enter recv_msg_recv_userauth_info_request"))

      /* Let the user know what password/host they are authing for */
      if (!cli_ses.interact_request_received) {
            fprintf(stderr, "Login for %s@%s\n", cli_opts.username,
                        cli_opts.remotehost);
      }
      cli_ses.interact_request_received = 1;

      name = buf_getstring(ses.payload, NULL);
      instruction = buf_getstring(ses.payload, NULL);

      /* language tag */
      buf_eatstring(ses.payload);

      num_prompts = buf_getint(ses.payload);
      
      if (num_prompts >= DROPBEAR_MAX_CLI_INTERACT_PROMPTS) {
            dropbear_exit("Too many prompts received for keyboard-interactive");
      }

      /* we'll build the response as we go */
      CHECKCLEARTOWRITE();
      buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_INFO_RESPONSE);
      buf_putint(ses.writepayload, num_prompts);

      if (strlen(name) > 0) {
            cleantext(name);
            fprintf(stderr, "%s", name);
      }
      m_free(name);

      if (strlen(instruction) > 0) {
            cleantext(instruction);
            fprintf(stderr, "%s", instruction);
      }
      m_free(instruction);

      for (i = 0; i < num_prompts; i++) {
            unsigned int response_len = 0;
            prompt = buf_getstring(ses.payload, NULL);
            cleantext(prompt);

            echo = buf_getbool(ses.payload);

            if (!echo) {
                  unsigned char* p = getpass_or_cancel(prompt);
                  response = m_strdup(p);
                  m_burn(p, strlen(p));
            } else {
                  response = get_response(prompt);
            }

            response_len = strlen(response);
            buf_putstring(ses.writepayload, response, response_len);
            m_burn(response, response_len);
            m_free(response);
      }

      encrypt_packet();


      TRACE(("leave recv_msg_recv_userauth_info_request"))
}

void cli_auth_interactive() {

      TRACE(("enter cli_auth_interactive"))
      CHECKCLEARTOWRITE();

      buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_REQUEST);

      /* username */
      buf_putstring(ses.writepayload, cli_opts.username,
                  strlen(cli_opts.username));

      /* service name */
      buf_putstring(ses.writepayload, SSH_SERVICE_CONNECTION, 
                  SSH_SERVICE_CONNECTION_LEN);

      /* method */
      buf_putstring(ses.writepayload, AUTH_METHOD_INTERACT,
                  AUTH_METHOD_INTERACT_LEN);

      /* empty language tag */
      buf_putstring(ses.writepayload, "", 0);

      /* empty submethods */
      buf_putstring(ses.writepayload, "", 0);

      encrypt_packet();
      cli_ses.interact_request_received = 0;

      TRACE(("leave cli_auth_interactive"))

}
#endif      /* ENABLE_CLI_INTERACT_AUTH */