guacamole-spice-protocol/src/guacd/connection.c

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/*
* Copyright (C) 2014 Glyptodon LLC
*
* 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 "config.h"
#include "connection.h"
#include "log.h"
#include "move-fd.h"
#include "proc.h"
#include "proc-map.h"
#include "user.h"
#include <guacamole/client.h>
#include <guacamole/error.h>
#include <guacamole/parser.h>
#include <guacamole/plugin.h>
#include <guacamole/protocol.h>
#include <guacamole/socket.h>
#include <guacamole/user.h>
#ifdef ENABLE_SSL
#include <openssl/ssl.h>
#include "socket-ssl.h"
#endif
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
/**
* Behaves exactly as write(), but writes as much as possible, returning
* successfully only if the entire buffer was written. If the write fails for
* any reason, a negative value is returned.
*
* @param fd
* The file descriptor to write to.
*
* @param buffer
* The buffer containing the data to be written.
*
* @param length
* The number of bytes in the buffer to write.
*
* @return
* The number of bytes written, or -1 if an error occurs. As this function
* is guaranteed to write ALL bytes, this will always be the number of
* bytes specified by length unless an error occurs.
*/
static int __write_all(int fd, char* buffer, int length) {
/* Repeatedly write() until all data is written */
while (length > 0) {
int written = write(fd, buffer, length);
if (written < 0)
return -1;
length -= written;
buffer += written;
}
return length;
}
/**
* Continuously reads from a guac_socket, writing all data read to a file
* descriptor. Any data already buffered from that guac_socket by a given
* guac_parser is read first, prior to reading further data from the
* guac_socket. The provided guac_parser will be freed once its buffers have
* been emptied, but the guac_socket will not.
*
* This thread ultimately terminates when no further data can be read from the
* guac_socket.
*
* @param data
* A pointer to a guacd_connection_io_thread_params structure containing
* the guac_socket to read from, the file descriptor to write the read data
* to, and the guac_parser associated with the guac_socket which may have
* unhandled data in its parsing buffers.
*
* @return
* Always NULL.
*/
static void* guacd_connection_write_thread(void* data) {
guacd_connection_io_thread_params* params = (guacd_connection_io_thread_params*) data;
char buffer[8192];
int length;
/* Read all buffered data from parser first */
while ((length = guac_parser_shift(params->parser, buffer, sizeof(buffer))) > 0) {
if (__write_all(params->fd, buffer, length) < 0)
break;
}
/* Parser is no longer needed */
guac_parser_free(params->parser);
/* Transfer data from file descriptor to socket */
while ((length = guac_socket_read(params->socket, buffer, sizeof(buffer))) > 0) {
if (__write_all(params->fd, buffer, length) < 0)
break;
}
return NULL;
}
void* guacd_connection_io_thread(void* data) {
guacd_connection_io_thread_params* params = (guacd_connection_io_thread_params*) data;
char buffer[8192];
int length;
pthread_t write_thread;
pthread_create(&write_thread, NULL, guacd_connection_write_thread, params);
/* Transfer data from file descriptor to socket */
while ((length = read(params->fd, buffer, sizeof(buffer))) > 0) {
if (guac_socket_write(params->socket, buffer, length))
break;
guac_socket_flush(params->socket);
}
/* Wait for write thread to die */
pthread_join(write_thread, NULL);
/* Clean up */
guac_socket_free(params->socket);
close(params->fd);
free(params);
return NULL;
}
/**
* Adds the given socket as a new user to the given process, automatically
* reading/writing from the socket via read/write threads. The given socket,
* parser, and any associated resources will be freed unless the user is not
* added successfully.
*
* If adding the user fails for any reason, non-zero is returned. Zero is
* returned upon success.
*
* @param proc
* The existing process to add the user to.
*
* @param parser
* The parser associated with the given guac_socket (used to handle the
* user's connection handshake thus far).
*
* @param socket
* The socket associated with the user to be added to the existing
* process.
*
* @return
* Zero if the user was added successfully, non-zero if an error occurred.
*/
static int guacd_add_user(guacd_proc* proc, guac_parser* parser, guac_socket* socket) {
int sockets[2];
/* Set up socket pair */
if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) < 0) {
guacd_log(GUAC_LOG_ERROR, "Unable to allocate file descriptors for I/O transfer: %s", strerror(errno));
return 1;
}
int user_fd = sockets[0];
int proc_fd = sockets[1];
/* Send user file descriptor to process */
if (!guacd_send_fd(proc->fd_socket, proc_fd)) {
guacd_log(GUAC_LOG_ERROR, "Unable to add user.");
return 1;
}
/* Close our end of the process file descriptor */
close(proc_fd);
guacd_connection_io_thread_params* params = malloc(sizeof(guacd_connection_io_thread_params));
params->parser = parser;
params->socket = socket;
params->fd = user_fd;
/* Start I/O thread */
pthread_t io_thread;
pthread_create(&io_thread, NULL, guacd_connection_io_thread, params);
pthread_detach(io_thread);
return 0;
}
/**
* Routes the connection on the given socket according to the Guacamole
* protocol, adding new users and creating new client processes as needed. If a
* new process is created, this function blocks until that process terminates,
* automatically deregistering the process at that point.
*
* The socket provided will be automatically freed when the connection
* terminates unless routing fails, in which case non-zero is returned.
*
* @param map
* The map of existing client processes.
*
* @param socket
* The socket associated with the new connection that must be routed to
* a new or existing process within the given map.
*
* @return
* Zero if the connection was successfully routed, non-zero if routing has
* failed.
*/
static int guacd_route_connection(guacd_proc_map* map, guac_socket* socket) {
guac_parser* parser = guac_parser_alloc();
/* Reset guac_error */
guac_error = GUAC_STATUS_SUCCESS;
guac_error_message = NULL;
/* Get protocol from select instruction */
if (guac_parser_expect(parser, socket, GUACD_USEC_TIMEOUT, "select")) {
/* Log error */
guacd_log_handshake_failure();
guacd_log_guac_error(GUAC_LOG_DEBUG,
"Error reading \"select\"");
guac_parser_free(parser);
return 1;
}
/* Validate args to select */
if (parser->argc != 1) {
/* Log error */
guacd_log_handshake_failure();
guacd_log(GUAC_LOG_ERROR, "Bad number of arguments to \"select\" (%i)",
parser->argc);
guac_parser_free(parser);
return 1;
}
guacd_proc* proc;
int new_process;
const char* identifier = parser->argv[0];
/* If connection ID, retrieve existing process */
if (identifier[0] == GUAC_CLIENT_ID_PREFIX) {
proc = guacd_proc_map_retrieve(map, identifier);
new_process = 0;
/* Warn if requested connection does not exist */
if (proc == NULL)
guacd_log(GUAC_LOG_INFO, "Connection \"%s\" does not exist.",
identifier);
else
guacd_log(GUAC_LOG_INFO, "Joining existing connection \"%s\"",
identifier);
}
/* Otherwise, create new client */
else {
guacd_log(GUAC_LOG_INFO, "Creating new client for protocol \"%s\"",
identifier);
/* Create new process */
proc = guacd_create_proc(identifier);
new_process = 1;
}
/* Abort if no process exists for the requested connection */
if (proc == NULL) {
guacd_log_guac_error(GUAC_LOG_INFO, "Connection did not succeed");
guac_parser_free(parser);
return 1;
}
/* Add new user (in the case of a new process, this will be the owner */
int add_user_failed = guacd_add_user(proc, parser, socket);
/* If new process was created, manage that process */
if (new_process) {
/* The new process will only be active if the user was added */
if (!add_user_failed) {
/* Log connection ID */
guacd_log(GUAC_LOG_INFO, "Connection ID is \"%s\"",
proc->client->connection_id);
/* Store process, allowing other users to join */
guacd_proc_map_add(map, proc);
/* Wait for child to finish */
waitpid(proc->pid, NULL, 0);
/* Remove client */
if (guacd_proc_map_remove(map, proc->client->connection_id) == NULL)
guacd_log(GUAC_LOG_ERROR, "Internal failure removing "
"client \"%s\". Client record will never be freed.",
proc->client->connection_id);
else
guacd_log(GUAC_LOG_INFO, "Connection \"%s\" removed.",
proc->client->connection_id);
}
/* Parser must be manually freed if the process did not start */
else
guac_parser_free(parser);
/* Force process to stop and clean up */
guacd_proc_stop(proc);
/* Free skeleton client */
guac_client_free(proc->client);
/* Clean up */
close(proc->fd_socket);
free(proc);
}
/* Routing succeeded only if the user was added to a process */
return add_user_failed;
}
void* guacd_connection_thread(void* data) {
guacd_connection_thread_params* params = (guacd_connection_thread_params*) data;
guacd_proc_map* map = params->map;
int connected_socket_fd = params->connected_socket_fd;
guac_socket* socket;
#ifdef ENABLE_SSL
SSL_CTX* ssl_context = params->ssl_context;
/* If SSL chosen, use it */
if (ssl_context != NULL) {
socket = guac_socket_open_secure(ssl_context, connected_socket_fd);
if (socket == NULL) {
guacd_log_guac_error(GUAC_LOG_ERROR, "Unable to set up SSL/TLS");
free(params);
return NULL;
}
}
else
socket = guac_socket_open(connected_socket_fd);
#else
/* Open guac_socket */
socket = guac_socket_open(connected_socket_fd);
#endif
/* Route connection according to Guacamole, creating a new process if needed */
if (guacd_route_connection(map, socket))
guac_socket_free(socket);
free(params);
return NULL;
}