src/messages.c


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/*
 * messages.c - message parsing for client and server
 *
 * 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.
 */

#include "config.h"

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

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

#include "libssh/libssh.h"
#include "libssh/priv.h"
#include "libssh/ssh2.h"
#include "libssh/buffer.h"
#include "libssh/packet.h"
#include "libssh/channels.h"
#include "libssh/session.h"
#include "libssh/misc.h"
#include "libssh/pki.h"
#include "libssh/dh.h"
#include "libssh/messages.h"
#ifdef WITH_SERVER
#include "libssh/server.h"
#include "libssh/gssapi.h"
#endif

/**
 * @defgroup libssh_messages The SSH message functions
 * @ingroup libssh
 *
 * This file contains the message parsing utilities for client and server
 * programs using libssh.
 *
 * On the server the the main loop of the program will call
 * ssh_message_get(session) to get messages as they come. They are not 1-1 with
 * the protocol messages. Then, the user will know what kind of a message it is
 * and use the appropriate functions to handle it (or use the default handlers
 * if you don't know what to do).
 *
 * @{
 */

static ssh_message ssh_message_new(ssh_session session){
  ssh_message msg = malloc(sizeof(struct ssh_message_struct));
  if (msg == NULL) {
    return NULL;
  }
  ZERO_STRUCTP(msg);
  msg->session = session;
  return msg;
}

#ifndef WITH_SERVER

/* Reduced version of the reply default that only reply with
 * SSH_MSG_UNIMPLEMENTED
 */
static int ssh_message_reply_default(ssh_message msg) {
  SSH_LOG(SSH_LOG_FUNCTIONS, "Reporting unknown packet");

  if (buffer_add_u8(msg->session->out_buffer, SSH2_MSG_UNIMPLEMENTED) < 0)
    goto error;
  if (buffer_add_u32(msg->session->out_buffer,
      htonl(msg->session->recv_seq-1)) < 0)
    goto error;
  return packet_send(msg->session);
  error:
  return SSH_ERROR;
}

#endif

#ifdef WITH_SERVER

static int ssh_execute_server_request(ssh_session session, ssh_message msg)
{
    ssh_channel channel = NULL;
    int rc;

    switch(msg->type) {
        case SSH_REQUEST_AUTH:
            if (msg->auth_request.method == SSH_AUTH_METHOD_PASSWORD &&
                ssh_callbacks_exists(session->server_callbacks, auth_password_function)) {
                rc = session->server_callbacks->auth_password_function(session,
                        msg->auth_request.username, msg->auth_request.password,
                        session->server_callbacks->userdata);
                if (rc == SSH_AUTH_SUCCESS || rc == SSH_AUTH_PARTIAL) {
                    ssh_message_auth_reply_success(msg, rc == SSH_AUTH_PARTIAL);
                } else {
                    ssh_message_reply_default(msg);
                }

                return SSH_OK;
            } else if(msg->auth_request.method == SSH_AUTH_METHOD_PUBLICKEY &&
                      ssh_callbacks_exists(session->server_callbacks, auth_pubkey_function)) {
               rc = session->server_callbacks->auth_pubkey_function(session,
                       msg->auth_request.username, msg->auth_request.pubkey,
                       msg->auth_request.signature_state,
                       session->server_callbacks->userdata);
               if (msg->auth_request.signature_state != SSH_PUBLICKEY_STATE_NONE) {
                 if (rc == SSH_AUTH_SUCCESS || rc == SSH_AUTH_PARTIAL) {
                   ssh_message_auth_reply_success(msg, rc == SSH_AUTH_PARTIAL);
                 } else {
                   ssh_message_reply_default(msg);
                 }
               } else {
                 if (rc == SSH_AUTH_SUCCESS) {
                   ssh_message_auth_reply_pk_ok_simple(msg);
                 } else {
                   ssh_message_reply_default(msg);
                 }
               }

               return SSH_OK;
            } else if (msg->auth_request.method == SSH_AUTH_METHOD_NONE &&
                       ssh_callbacks_exists(session->server_callbacks, auth_none_function)) {
                rc = session->server_callbacks->auth_none_function(session,
                    msg->auth_request.username, session->server_callbacks->userdata);
                if (rc == SSH_AUTH_SUCCESS || rc == SSH_AUTH_PARTIAL){
                    ssh_message_auth_reply_success(msg, rc == SSH_AUTH_PARTIAL);
                } else {
                    ssh_message_reply_default(msg);
                }

                return SSH_OK;
            }
            break;
        case SSH_REQUEST_CHANNEL_OPEN:
            if (msg->channel_request_open.type == SSH_CHANNEL_SESSION &&
                ssh_callbacks_exists(session->server_callbacks, channel_open_request_session_function)) {
                channel = session->server_callbacks->channel_open_request_session_function(session,
                        session->server_callbacks->userdata);
                if (channel != NULL) {
                    rc = ssh_message_channel_request_open_reply_accept_channel(msg, channel);
                    return SSH_OK;
                } else {
                    ssh_message_reply_default(msg);
                }

                return SSH_OK;
            }
            break;
        case SSH_REQUEST_CHANNEL:
            channel = msg->channel_request.channel;

            if (msg->channel_request.type == SSH_CHANNEL_REQUEST_PTY &&
                ssh_callbacks_exists(channel->callbacks, channel_pty_request_function)) {
                rc = channel->callbacks->channel_pty_request_function(session, channel,
                        msg->channel_request.TERM,
                        msg->channel_request.width, msg->channel_request.height,
                        msg->channel_request.pxwidth, msg->channel_request.pxheight,
                        channel->callbacks->userdata);
                if (rc == 0) {
                    ssh_message_channel_request_reply_success(msg);
                } else {
                    ssh_message_reply_default(msg);
                }

                return SSH_OK;
            } else if (msg->channel_request.type == SSH_CHANNEL_REQUEST_SHELL &&
                      ssh_callbacks_exists(channel->callbacks, channel_shell_request_function)) {
                rc = channel->callbacks->channel_shell_request_function(session,
                                                                        channel,
                                                                        channel->callbacks->userdata);
                if (rc == 0) {
                    ssh_message_channel_request_reply_success(msg);
                } else {
                    ssh_message_reply_default(msg);
                }

                return SSH_OK;
            } else if (msg->channel_request.type == SSH_CHANNEL_REQUEST_X11 &&
                      ssh_callbacks_exists(channel->callbacks, channel_x11_req_function)) {
                channel->callbacks->channel_x11_req_function(session,
                                                             channel,
                                                             msg->channel_request.x11_single_connection,
                                                             msg->channel_request.x11_auth_protocol,
                                                             msg->channel_request.x11_auth_cookie,
                                                             msg->channel_request.x11_screen_number,
                                                             channel->callbacks->userdata);
                ssh_message_channel_request_reply_success(msg);

                return SSH_OK;
            } else if (msg->channel_request.type == SSH_CHANNEL_REQUEST_WINDOW_CHANGE &&
                       ssh_callbacks_exists(channel->callbacks, channel_pty_window_change_function)) {
                rc = channel->callbacks->channel_pty_window_change_function(session,
                                                                            channel,
                                                                            msg->channel_request.width, msg->channel_request.height,
                                                                            msg->channel_request.pxwidth, msg->channel_request.pxheight,
                                                                            channel->callbacks->userdata);
            } else if (msg->channel_request.type == SSH_CHANNEL_REQUEST_EXEC &&
                       ssh_callbacks_exists(channel->callbacks, channel_exec_request_function)) {
                rc = channel->callbacks->channel_exec_request_function(session,
                                                                       channel,
                                                                       msg->channel_request.command,
                                                                       channel->callbacks->userdata);
                if (rc == 0) {
                    ssh_message_channel_request_reply_success(msg);
                } else {
                    ssh_message_reply_default(msg);
                }

                return SSH_OK;
            } else if (msg->channel_request.type == SSH_CHANNEL_REQUEST_ENV &&
                       ssh_callbacks_exists(channel->callbacks, channel_env_request_function)) {
                rc = channel->callbacks->channel_env_request_function(session,
                                                                      channel,
                                                                      msg->channel_request.var_name, msg->channel_request.var_value,
                                                                      channel->callbacks->userdata);
                if (rc == 0) {
                    ssh_message_channel_request_reply_success(msg);
                } else {
                    ssh_message_reply_default(msg);
                }

                return SSH_OK;
            } else if (msg->channel_request.type == SSH_CHANNEL_REQUEST_SUBSYSTEM &&
                       ssh_callbacks_exists(channel->callbacks, channel_subsystem_request_function)) {
                rc = channel->callbacks->channel_subsystem_request_function(session,
                                                                            channel,
                                                                            msg->channel_request.subsystem,
                                                                            channel->callbacks->userdata);
                if (rc == 0) {
                    ssh_message_channel_request_reply_success(msg);
                } else {
                    ssh_message_reply_default(msg);
                }

                return SSH_OK;
            }
            break;
        case SSH_REQUEST_SERVICE:
            if (ssh_callbacks_exists(session->server_callbacks, service_request_function)) {
                rc = session->server_callbacks->service_request_function(session,
                        msg->service_request.service, session->server_callbacks->userdata);
                if (rc == 0) {
                    ssh_message_reply_default(msg);
                } else {
                    ssh_disconnect(session);
                }

                return SSH_OK;
            }

            return SSH_AGAIN;
        case SSH_REQUEST_GLOBAL:
            break;
    }

    return SSH_AGAIN;
}

static int ssh_execute_client_request(ssh_session session, ssh_message msg)
{
    ssh_channel channel = NULL;
    int rc = SSH_AGAIN;