393 lines
12 KiB
C
393 lines
12 KiB
C
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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#include "config.h"
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#include "guac_recording.h"
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#include "guac_sftp.h"
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#include "guac_ssh.h"
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#include "settings.h"
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#include "sftp.h"
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#include "ssh.h"
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#include "terminal.h"
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#ifdef ENABLE_SSH_AGENT
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#include "ssh_agent.h"
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#endif
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#include <libssh2.h>
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#include <libssh2_sftp.h>
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#include <guacamole/client.h>
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#include <openssl/err.h>
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#include <openssl/ssl.h>
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#ifdef LIBSSH2_USES_GCRYPT
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#include <gcrypt.h>
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#endif
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#include <errno.h>
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#include <netdb.h>
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#include <netinet/in.h>
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#include <pthread.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/select.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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/**
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* Produces a new user object containing a username and password or private
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* key, prompting the user as necessary to obtain that information.
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*
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* @param client
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* The Guacamole client containing any existing user data, as well as the
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* terminal to use when prompting the user.
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*
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* @return
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* A new user object containing the user's username and other credentials.
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*/
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static guac_common_ssh_user* guac_ssh_get_user(guac_client* client) {
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guac_ssh_client* ssh_client = (guac_ssh_client*) client->data;
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guac_ssh_settings* settings = ssh_client->settings;
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guac_common_ssh_user* user;
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/* Get username */
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if (settings->username == NULL)
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settings->username = guac_terminal_prompt(ssh_client->term,
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"Login as: ", true);
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/* Create user object from username */
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user = guac_common_ssh_create_user(settings->username);
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/* If key specified, import */
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if (settings->key_base64 != NULL) {
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guac_client_log(client, GUAC_LOG_DEBUG,
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"Attempting private key import (WITHOUT passphrase)");
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/* Attempt to read key without passphrase */
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if (guac_common_ssh_user_import_key(user,
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settings->key_base64, NULL)) {
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/* Log failure of initial attempt */
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guac_client_log(client, GUAC_LOG_DEBUG,
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"Initial import failed: %s",
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guac_common_ssh_key_error());
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guac_client_log(client, GUAC_LOG_DEBUG,
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"Re-attempting private key import (WITH passphrase)");
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/* Prompt for passphrase if missing */
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if (settings->key_passphrase == NULL)
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settings->key_passphrase =
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guac_terminal_prompt(ssh_client->term,
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"Key passphrase: ", false);
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/* Reattempt import with passphrase */
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if (guac_common_ssh_user_import_key(user,
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settings->key_base64,
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settings->key_passphrase)) {
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/* If still failing, give up */
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guac_client_abort(client,
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GUAC_PROTOCOL_STATUS_CLIENT_UNAUTHORIZED,
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"Auth key import failed: %s",
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guac_common_ssh_key_error());
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guac_common_ssh_destroy_user(user);
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return NULL;
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}
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} /* end decrypt key with passphrase */
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/* Success */
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guac_client_log(client, GUAC_LOG_INFO,
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"Auth key successfully imported.");
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} /* end if key given */
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/* Otherwise, use password */
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else {
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/* Get password if not provided */
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if (settings->password == NULL)
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settings->password = guac_terminal_prompt(ssh_client->term,
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"Password: ", false);
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/* Set provided password */
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guac_common_ssh_user_set_password(user, settings->password);
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}
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/* Clear screen of any prompts */
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guac_terminal_printf(ssh_client->term, "\x1B[H\x1B[J");
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return user;
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}
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void* ssh_input_thread(void* data) {
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guac_client* client = (guac_client*) data;
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guac_ssh_client* ssh_client = (guac_ssh_client*) client->data;
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char buffer[8192];
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int bytes_read;
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/* Write all data read */
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while ((bytes_read = guac_terminal_read_stdin(ssh_client->term, buffer, sizeof(buffer))) > 0) {
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pthread_mutex_lock(&(ssh_client->term_channel_lock));
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libssh2_channel_write(ssh_client->term_channel, buffer, bytes_read);
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pthread_mutex_unlock(&(ssh_client->term_channel_lock));
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}
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return NULL;
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}
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void* ssh_client_thread(void* data) {
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guac_client* client = (guac_client*) data;
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guac_ssh_client* ssh_client = (guac_ssh_client*) client->data;
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guac_ssh_settings* settings = ssh_client->settings;
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char buffer[8192];
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pthread_t input_thread;
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/* Init SSH base libraries */
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if (guac_common_ssh_init(client)) {
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guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR,
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"SSH library initialization failed");
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return NULL;
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}
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/* Set up screen recording, if requested */
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if (settings->recording_path != NULL) {
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guac_common_recording_create(client,
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settings->recording_path,
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settings->recording_name,
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settings->create_recording_path);
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}
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/* Create terminal */
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ssh_client->term = guac_terminal_create(client,
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settings->font_name, settings->font_size,
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settings->resolution, settings->width, settings->height,
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settings->color_scheme);
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/* Fail if terminal init failed */
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if (ssh_client->term == NULL) {
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guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR,
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"Terminal initialization failed");
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return NULL;
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}
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/* Set up typescript, if requested */
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if (settings->typescript_path != NULL) {
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guac_terminal_create_typescript(ssh_client->term,
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settings->typescript_path,
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settings->typescript_name,
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settings->create_typescript_path);
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}
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/* Get user and credentials */
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ssh_client->user = guac_ssh_get_user(client);
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/* Open SSH session */
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ssh_client->session = guac_common_ssh_create_session(client,
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settings->hostname, settings->port, ssh_client->user);
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if (ssh_client->session == NULL) {
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/* Already aborted within guac_common_ssh_create_session() */
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return NULL;
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}
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pthread_mutex_init(&ssh_client->term_channel_lock, NULL);
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/* Open channel for terminal */
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ssh_client->term_channel =
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libssh2_channel_open_session(ssh_client->session->session);
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if (ssh_client->term_channel == NULL) {
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guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR,
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"Unable to open terminal channel.");
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return NULL;
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}
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#ifdef ENABLE_SSH_AGENT
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/* Start SSH agent forwarding, if enabled */
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if (ssh_client->enable_agent) {
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libssh2_session_callback_set(ssh_client->session,
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LIBSSH2_CALLBACK_AUTH_AGENT, (void*) ssh_auth_agent_callback);
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/* Request agent forwarding */
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if (libssh2_channel_request_auth_agent(ssh_client->term_channel))
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guac_client_log(client, GUAC_LOG_ERROR, "Agent forwarding request failed");
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else
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guac_client_log(client, GUAC_LOG_INFO, "Agent forwarding enabled.");
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}
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ssh_client->auth_agent = NULL;
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#endif
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/* Start SFTP session as well, if enabled */
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if (settings->enable_sftp) {
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/* Create SSH session specific for SFTP */
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guac_client_log(client, GUAC_LOG_DEBUG, "Reconnecting for SFTP...");
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ssh_client->sftp_session =
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guac_common_ssh_create_session(client, settings->hostname,
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settings->port, ssh_client->user);
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if (ssh_client->sftp_session == NULL) {
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/* Already aborted within guac_common_ssh_create_session() */
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return NULL;
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}
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/* Request SFTP */
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ssh_client->sftp_filesystem = guac_common_ssh_create_sftp_filesystem(
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ssh_client->sftp_session, "/");
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/* Expose filesystem to connection owner */
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guac_client_for_owner(client,
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guac_common_ssh_expose_sftp_filesystem,
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ssh_client->sftp_filesystem);
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/* Init handlers for Guacamole-specific console codes */
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ssh_client->term->upload_path_handler = guac_sftp_set_upload_path;
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ssh_client->term->file_download_handler = guac_sftp_download_file;
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guac_client_log(client, GUAC_LOG_DEBUG, "SFTP session initialized");
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}
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/* Request PTY */
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if (libssh2_channel_request_pty_ex(ssh_client->term_channel, "linux", sizeof("linux")-1, NULL, 0,
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ssh_client->term->term_width, ssh_client->term->term_height, 0, 0)) {
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guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR, "Unable to allocate PTY.");
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return NULL;
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}
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/* If a command is specified, run that instead of a shell */
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if (settings->command != NULL) {
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if (libssh2_channel_exec(ssh_client->term_channel, settings->command)) {
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guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR,
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"Unable to execute command.");
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return NULL;
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}
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}
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/* Otherwise, request a shell */
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else if (libssh2_channel_shell(ssh_client->term_channel)) {
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guac_client_abort(client, GUAC_PROTOCOL_STATUS_UPSTREAM_ERROR,
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"Unable to associate shell with PTY.");
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return NULL;
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}
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/* Logged in */
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guac_client_log(client, GUAC_LOG_INFO, "SSH connection successful.");
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/* Start input thread */
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if (pthread_create(&(input_thread), NULL, ssh_input_thread, (void*) client)) {
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guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR, "Unable to start input thread");
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return NULL;
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}
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/* Set non-blocking */
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libssh2_session_set_blocking(ssh_client->session->session, 0);
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/* While data available, write to terminal */
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int bytes_read = 0;
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for (;;) {
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/* Track total amount of data read */
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int total_read = 0;
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pthread_mutex_lock(&(ssh_client->term_channel_lock));
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/* Stop reading at EOF */
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if (libssh2_channel_eof(ssh_client->term_channel)) {
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pthread_mutex_unlock(&(ssh_client->term_channel_lock));
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break;
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}
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/* Read terminal data */
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bytes_read = libssh2_channel_read(ssh_client->term_channel,
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buffer, sizeof(buffer));
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pthread_mutex_unlock(&(ssh_client->term_channel_lock));
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/* Attempt to write data received. Exit on failure. */
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if (bytes_read > 0) {
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int written = guac_terminal_write_stdout(ssh_client->term, buffer, bytes_read);
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if (written < 0)
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break;
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total_read += bytes_read;
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}
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else if (bytes_read < 0 && bytes_read != LIBSSH2_ERROR_EAGAIN)
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break;
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#ifdef ENABLE_SSH_AGENT
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/* If agent open, handle any agent packets */
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if (ssh_client->auth_agent != NULL) {
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bytes_read = ssh_auth_agent_read(ssh_client->auth_agent);
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if (bytes_read > 0)
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total_read += bytes_read;
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else if (bytes_read < 0 && bytes_read != LIBSSH2_ERROR_EAGAIN)
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ssh_client->auth_agent = NULL;
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}
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#endif
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/* Wait for more data if reads turn up empty */
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if (total_read == 0) {
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fd_set fds;
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struct timeval timeout;
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FD_ZERO(&fds);
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FD_SET(ssh_client->session->fd, &fds);
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/* Wait for one second */
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timeout.tv_sec = 1;
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timeout.tv_usec = 0;
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if (select(ssh_client->session->fd + 1, &fds,
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NULL, NULL, &timeout) < 0)
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break;
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}
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}
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/* Kill client and Wait for input thread to die */
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guac_client_stop(client);
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pthread_join(input_thread, NULL);
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pthread_mutex_destroy(&ssh_client->term_channel_lock);
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guac_client_log(client, GUAC_LOG_INFO, "SSH connection ended.");
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return NULL;
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}
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