/**
* Starts protocol-specific handling on the given process by loading the client
* plugin for that protocol. This function does NOT return. It initializes the
* process with protocol-specific handlers and then runs until the guacd_proc's
* fd_socket is closed, adding any file descriptors received along fd_socket as
* new users.
*
* @param proc
* The process that any new users received along fd_socket should be added
* to (after the process has been initialized for the given protocol).
*
* @param protocol
* The protocol to initialize the given process for.
*/
static void guacd_exec_proc(guacd_proc* proc, const char* protocol) {
/* Init client for selected protocol */
if (guac_client_load_plugin(proc->client, protocol)) {
/* Log error */
if (guac_error == GUAC_STATUS_NOT_FOUND)
guacd_log(GUAC_LOG_WARNING,
"Support for protocol \"%s\" is not installed", protocol);
else
guacd_log_guac_error(GUAC_LOG_ERROR,
"Unable to load client plugin");
guac_client_free(proc->client);
close(proc->fd_socket);
free(proc);
exit(1);
}
/* The first file descriptor is the owner */
int owner = 1;
/* Add each received file descriptor as a new user */
int received_fd;
while ((received_fd = guacd_recv_fd(proc->fd_socket)) != -1) {
guacd_proc_add_user(proc, received_fd, owner);
/* Future file descriptors are not owners */
owner = 0;
}
/* Stop and free client */
guac_client_stop(proc->client);
guac_client_free(proc->client);
/* Child is finished */
close(proc->fd_socket);
free(proc);
exit(0);
}
/**
* Creates a new guac_client for the connection on the given socket, adding
* it to the client map based on its ID.
*/
static void guacd_handle_connection(guacd_client_map* map, guac_socket* socket) {
guac_client* client;
guac_client_plugin* plugin;
guac_instruction* select;
guac_instruction* size;
guac_instruction* audio;
guac_instruction* video;
guac_instruction* connect;
int init_result;
/* Reset guac_error */
guac_error = GUAC_STATUS_SUCCESS;
guac_error_message = NULL;
/* Get protocol from select instruction */
select = guac_instruction_expect(
socket, GUACD_USEC_TIMEOUT, "select");
if (select == NULL) {
/* Log error */
guacd_log_guac_error("Error reading \"select\"");
/* Free resources */
guac_socket_free(socket);
return;
}
/* Validate args to select */
if (select->argc != 1) {
/* Log error */
guacd_log_error("Bad number of arguments to \"select\" (%i)",
select->argc);
/* Free resources */
guac_socket_free(socket);
return;
}
guacd_log_info("Protocol \"%s\" selected", select->argv[0]);
/* Get plugin from protocol in select */
plugin = guac_client_plugin_open(select->argv[0]);
guac_instruction_free(select);
if (plugin == NULL) {
/* Log error */
guacd_log_guac_error("Error loading client plugin");
/* Free resources */
guac_socket_free(socket);
return;
}
/* Send args response */
if (guac_protocol_send_args(socket, plugin->args)
|| guac_socket_flush(socket)) {
/* Log error */
guacd_log_guac_error("Error sending \"args\"");
if (guac_client_plugin_close(plugin))
guacd_log_guac_error("Error closing client plugin");
guac_socket_free(socket);
return;
}
/* Get optimal screen size */
size = guac_instruction_expect(
socket, GUACD_USEC_TIMEOUT, "size");
if (size == NULL) {
/* Log error */
guacd_log_guac_error("Error reading \"size\"");
/* Free resources */
guac_socket_free(socket);
return;
}
/* Get supported audio formats */
audio = guac_instruction_expect(
socket, GUACD_USEC_TIMEOUT, "audio");
if (audio == NULL) {
/* Log error */
guacd_log_guac_error("Error reading \"audio\"");
/* Free resources */
guac_socket_free(socket);
return;
}
/* Get supported video formats */
video = guac_instruction_expect(
socket, GUACD_USEC_TIMEOUT, "video");
if (video == NULL) {
/* Log error */
guacd_log_guac_error("Error reading \"video\"");
/* Free resources */
guac_socket_free(socket);
return;
}
/* Get args from connect instruction */
connect = guac_instruction_expect(
socket, GUACD_USEC_TIMEOUT, "connect");
if (connect == NULL) {
/* Log error */
guacd_log_guac_error("Error reading \"connect\"");
if (guac_client_plugin_close(plugin))
guacd_log_guac_error("Error closing client plugin");
guac_socket_free(socket);
return;
}
/* Get client */
client = guac_client_alloc();
if (client == NULL) {
guacd_log_guac_error("Client could not be allocated");
guac_socket_free(socket);
return;
}
client->socket = socket;
client->log_info_handler = guacd_client_log_info;
client->log_error_handler = guacd_client_log_error;
/* Parse optimal screen dimensions from size instruction */
client->info.optimal_width = atoi(size->argv[0]);
client->info.optimal_height = atoi(size->argv[1]);
/* If DPI given, set the client resolution */
if (size->argc >= 3)
client->info.optimal_resolution = atoi(size->argv[2]);
/* Otherwise, use a safe default for rough backwards compatibility */
else
client->info.optimal_resolution = 96;
/* Store audio mimetypes */
client->info.audio_mimetypes = malloc(sizeof(char*) * (audio->argc+1));
memcpy(client->info.audio_mimetypes, audio->argv,
sizeof(char*) * audio->argc);
client->info.audio_mimetypes[audio->argc] = NULL;
/* Store video mimetypes */
client->info.video_mimetypes = malloc(sizeof(char*) * (video->argc+1));
memcpy(client->info.video_mimetypes, video->argv,
sizeof(char*) * video->argc);
client->info.video_mimetypes[video->argc] = NULL;
/* Store client */
if (guacd_client_map_add(map, client))
guacd_log_error("Unable to add client. Internal client storage has failed");
/* Send connection ID */
guacd_log_info("Connection ID is \"%s\"", client->connection_id);
guac_protocol_send_ready(socket, client->connection_id);
/* Init client */
init_result = guac_client_plugin_init_client(plugin,
client, connect->argc, connect->argv);
guac_instruction_free(connect);
/* If client could not be started, free everything and fail */
if (init_result) {
guac_client_free(client);
guacd_log_guac_error("Error instantiating client");
if (guac_client_plugin_close(plugin))
guacd_log_guac_error("Error closing client plugin");
guac_socket_free(socket);
return;
}
/* Start client threads */
guacd_log_info("Starting client");
if (guacd_client_start(client))
guacd_log_error("Client finished abnormally");
else
guacd_log_info("Client finished normally");
/* Remove client */
if (guacd_client_map_remove(map, client->connection_id) == NULL)
guacd_log_error("Unable to remove client. Internal client storage has failed");
/* Free mimetype lists */
free(client->info.audio_mimetypes);
free(client->info.video_mimetypes);
/* Free remaining instructions */
guac_instruction_free(audio);
guac_instruction_free(video);
guac_instruction_free(size);
/* Clean up */
guac_client_free(client);
if (guac_client_plugin_close(plugin))
guacd_log_error("Error closing client plugin");
/* Close socket */
guac_socket_free(socket);
}
int main(int argc, char* argv[]) {
/* Server */
int socket_fd;
struct addrinfo* addresses;
struct addrinfo* current_address;
char bound_address[1024];
char bound_port[64];
int opt_on = 1;
struct addrinfo hints = {
.ai_family = AF_UNSPEC,
.ai_socktype = SOCK_STREAM,
.ai_protocol = IPPROTO_TCP
};
/* Client */
struct sockaddr_in client_addr;
socklen_t client_addr_len;
int connected_socket_fd;
#ifdef ENABLE_SSL
SSL_CTX* ssl_context = NULL;
#endif
guacd_client_map* map = guacd_client_map_alloc();
/* General */
int retval;
/* Load configuration */
guacd_config* config = guacd_conf_load();
if (config == NULL || guacd_conf_parse_args(config, argc, argv))
exit(EXIT_FAILURE);
/* Set up logging prefix */
strncpy(log_prefix, basename(argv[0]), sizeof(log_prefix));
/* Open log as early as we can */
openlog(NULL, LOG_PID, LOG_DAEMON);
/* Log start */
guacd_log_info("Guacamole proxy daemon (guacd) version " VERSION);
/* Get addresses for binding */
if ((retval = getaddrinfo(config->bind_host, config->bind_port,
&hints, &addresses))) {
guacd_log_error("Error parsing given address or port: %s",
gai_strerror(retval));
exit(EXIT_FAILURE);
}
/* Get socket */
socket_fd = socket(AF_INET, SOCK_STREAM, 0);
if (socket_fd < 0) {
guacd_log_error("Error opening socket: %s", strerror(errno));
exit(EXIT_FAILURE);
}
/* Allow socket reuse */
if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR,
(void*) &opt_on, sizeof(opt_on))) {
guacd_log_info("Unable to set socket options for reuse: %s",
strerror(errno));
}
/* Attempt binding of each address until success */
current_address = addresses;
while (current_address != NULL) {
int retval;
/* Resolve hostname */
if ((retval = getnameinfo(current_address->ai_addr,
current_address->ai_addrlen,
bound_address, sizeof(bound_address),
bound_port, sizeof(bound_port),
NI_NUMERICHOST | NI_NUMERICSERV)))
guacd_log_error("Unable to resolve host: %s",
gai_strerror(retval));
/* Attempt to bind socket to address */
if (bind(socket_fd,
current_address->ai_addr,
current_address->ai_addrlen) == 0) {
guacd_log_info("Successfully bound socket to "
"host %s, port %s", bound_address, bound_port);
/* Done if successful bind */
break;
}
/* Otherwise log information regarding bind failure */
else
guacd_log_info("Unable to bind socket to "
"host %s, port %s: %s",
bound_address, bound_port, strerror(errno));
current_address = current_address->ai_next;
}
/* If unable to bind to anything, fail */
if (current_address == NULL) {
guacd_log_error("Unable to bind socket to any addresses.");
exit(EXIT_FAILURE);
}
#ifdef ENABLE_SSL
/* Init SSL if enabled */
if (config->key_file != NULL || config->cert_file != NULL) {
/* Init SSL */
guacd_log_info("Communication will require SSL/TLS.");
SSL_library_init();
SSL_load_error_strings();
ssl_context = SSL_CTX_new(SSLv23_server_method());
/* Load key */
if (config->key_file != NULL) {
guacd_log_info("Using PEM keyfile %s", config->key_file);
if (!SSL_CTX_use_PrivateKey_file(ssl_context, config->key_file, SSL_FILETYPE_PEM)) {
guacd_log_error("Unable to load keyfile.");
exit(EXIT_FAILURE);
}
}
else
guacd_log_info("No PEM keyfile given - SSL/TLS may not work.");
/* Load cert file if specified */
if (config->cert_file != NULL) {
guacd_log_info("Using certificate file %s", config->cert_file);
if (!SSL_CTX_use_certificate_chain_file(ssl_context, config->cert_file)) {
guacd_log_error("Unable to load certificate.");
exit(EXIT_FAILURE);
}
}
else
guacd_log_info("No certificate file given - SSL/TLS may not work.");
}
#endif
/* Daemonize if requested */
if (!config->foreground) {
/* Attempt to daemonize process */
if (daemonize()) {
guacd_log_error("Could not become a daemon.");
exit(EXIT_FAILURE);
}
}
/* Write PID file if requested */
if (config->pidfile != NULL) {
/* Attempt to open pidfile and write PID */
FILE* pidf = fopen(config->pidfile, "w");
if (pidf) {
fprintf(pidf, "%d\n", getpid());
fclose(pidf);
}
/* Fail if could not write PID file*/
else {
guacd_log_error("Could not write PID file: %s", strerror(errno));
exit(EXIT_FAILURE);
}
}
/* Ignore SIGPIPE */
if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
guacd_log_info("Could not set handler for SIGPIPE to ignore. "
"SIGPIPE may cause termination of the daemon.");
}
/* Ignore SIGCHLD (force automatic removal of children) */
if (signal(SIGCHLD, SIG_IGN) == SIG_ERR) {
guacd_log_info("Could not set handler for SIGCHLD to ignore. "
"Child processes may pile up in the process table.");
}
/* Log listening status */
guacd_log_info("Listening on host %s, port %s", bound_address, bound_port);
/* Free addresses */
freeaddrinfo(addresses);
/* Daemon loop */
for (;;) {
pid_t child_pid;
/* Listen for connections */
if (listen(socket_fd, 5) < 0) {
guacd_log_error("Could not listen on socket: %s", strerror(errno));
return 3;
}
/* Accept connection */
client_addr_len = sizeof(client_addr);
connected_socket_fd = accept(socket_fd,
(struct sockaddr*) &client_addr, &client_addr_len);
if (connected_socket_fd < 0) {
guacd_log_error("Could not accept client connection: %s",
strerror(errno));
return 3;
}
/*
* Once connection is accepted, send child into background.
*
* Note that we prefer fork() over threads for connection-handling
* processes as they give each connection its own memory area, and
* isolate the main daemon and other connections from errors in any
* particular client plugin.
*/
child_pid = fork();
/* If error, log */
if (child_pid == -1)
guacd_log_error("Error forking child process: %s", strerror(errno));
/* If child, start client, and exit when finished */
else if (child_pid == 0) {
guac_socket* socket;
#ifdef ENABLE_SSL
/* 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("Error opening secure connection");
return 0;
}
}
else
socket = guac_socket_open(connected_socket_fd);
#else
/* Open guac_socket */
socket = guac_socket_open(connected_socket_fd);
#endif
guacd_handle_connection(map, socket);
close(connected_socket_fd);
return 0;
}
/* If parent, close reference to child's descriptor */
else if (close(connected_socket_fd) < 0) {
guacd_log_error("Error closing daemon reference to "
"child descriptor: %s", strerror(errno));
}
}
/* Close socket */
if (close(socket_fd) < 0) {
guacd_log_error("Could not close socket: %s", strerror(errno));
return 3;
}
return 0;
}
guacd_proc* guacd_create_proc(const char* protocol) {
int sockets[2];
/* Open UNIX socket pair */
if (socketpair(AF_UNIX, SOCK_DGRAM, 0, sockets) < 0) {
guacd_log(GUAC_LOG_ERROR, "Error opening socket pair: %s", strerror(errno));
return NULL;
}
int parent_socket = sockets[0];
int child_socket = sockets[1];
/* Allocate process */
guacd_proc* proc = calloc(1, sizeof(guacd_proc));
if (proc == NULL) {
close(parent_socket);
close(child_socket);
return NULL;
}
/* Associate new client */
proc->client = guac_client_alloc();
if (proc->client == NULL) {
guacd_log_guac_error(GUAC_LOG_ERROR, "Unable to create client");
close(parent_socket);
close(child_socket);
free(proc);
return NULL;
}
/* Init logging */
proc->client->log_handler = guacd_client_log;
/* Fork */
proc->pid = fork();
if (proc->pid < 0) {
guacd_log(GUAC_LOG_ERROR, "Cannot fork child process: %s", strerror(errno));
close(parent_socket);
close(child_socket);
guac_client_free(proc->client);
free(proc);
return NULL;
}
/* Child */
else if (proc->pid == 0) {
/* Communicate with parent */
proc->fd_socket = parent_socket;
close(child_socket);
/* Start protocol-specific handling */
guacd_exec_proc(proc, protocol);
}
/* Parent */
else {
/* Communicate with child */
proc->fd_socket = child_socket;
close(parent_socket);
}
return proc;
}
