/***********************************************************/
/*
*
* The telnet DAEMON
*
* Author: 17,may 2001
*
* WORK: fernando.ruiz@ctv.es
* HOME: correo@fernando-ruiz.com
*
* After start the net you can start this daemon.
* It uses the previously inited pseudo-terminales (pty.c)
* getting a new terminal with getpty(). This function
* gives a terminal name passing a opened socket like parameter.
*
* With register_telnetd() you add a new command in the shell to start
* this daemon interactively. (Login in /dev/console of course)
*
* Sorry but OOB is not still implemented. (This is the first version)
*
* Till Straumann <strauman@slac.stanford.edu>
* - made the 'shell' interface more generic, i.e. it is now
* possible to have 'telnetd' run an arbitrary 'shell'
* program.
*
* Copyright (c) 2009, 2018 embedded brains GmbH and others.
*
* embedded brains GmbH
* Dornierstr. 4
* D-82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <sys/queue.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <inttypes.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <syslog.h>
#include <rtems.h>
#include <rtems/pty.h>
#include <rtems/shell.h>
#include <rtems/telnetd.h>
#include <rtems/thread.h>
#include <rtems/userenv.h>
#ifdef RTEMS_NETWORKING
#include <rtems/rtems_bsdnet.h>
#endif
#define TELNETD_EVENT_SUCCESS RTEMS_EVENT_0
#define TELNETD_EVENT_ERROR RTEMS_EVENT_1
typedef struct telnetd_context telnetd_context;
typedef struct telnetd_session {
rtems_pty_context pty;
char peername[16];
telnetd_context *ctx;
rtems_id task_id;
LIST_ENTRY(telnetd_session) link;
} telnetd_session;
struct telnetd_context {
rtems_telnetd_config_table config;
int server_socket;
rtems_id task_id;
rtems_mutex mtx;
LIST_HEAD(, telnetd_session) free_sessions;
telnetd_session sessions[RTEMS_ZERO_LENGTH_ARRAY];
};
typedef union {
struct sockaddr_in sin;
struct sockaddr sa;
} telnetd_address;
RTEMS_NO_RETURN static void telnetd_session_fatal_error(
const telnetd_context *ctx
)
{
(void)rtems_event_send(ctx->task_id, TELNETD_EVENT_ERROR);
rtems_task_exit();
}
static bool telnetd_login(telnetd_context *ctx, telnetd_session *session)
{
bool success;
if (ctx->config.login_check == NULL) {
return true;
}
success = rtems_shell_login_prompt(
stdin,
stderr,
session->pty.name,
ctx->config.login_check
);
if (!success) {
syslog(
LOG_AUTHPRIV | LOG_WARNING,
"telnetd: too many wrong passwords entered from %s",
session->peername
);
}
return success;
}
static void telnetd_session_task(rtems_task_argument arg)
{
rtems_status_code sc;
telnetd_session *session;
telnetd_context *ctx;
const char *path;
session = (telnetd_session *) arg;
ctx = session->ctx;
sc = rtems_libio_set_private_env();
if (sc != RTEMS_SUCCESSFUL) {
telnetd_session_fatal_error(ctx);
}
path = rtems_pty_get_path(&session->pty);
stdin = fopen(path, "r+");
if (stdin == NULL) {
telnetd_session_fatal_error(ctx);
}
stdout = fopen(path, "r+");
if (stdout == NULL) {
telnetd_session_fatal_error(ctx);
}
stderr = fopen(path, "r+");
if (stderr == NULL) {
telnetd_session_fatal_error(ctx);
}
(void)rtems_event_send(ctx->task_id, TELNETD_EVENT_SUCCESS);
while (true) {
rtems_event_set events;
(void)rtems_event_system_receive(
RTEMS_EVENT_SYSTEM_SERVER,
RTEMS_WAIT | RTEMS_EVENT_ALL,
RTEMS_NO_TIMEOUT,
&events
);
syslog(
LOG_DAEMON | LOG_INFO,
"telnetd: accepted connection from %s on %s",
session->peername,
path
);
if (telnetd_login(ctx, session)) {
(*ctx->config.command)(session->pty.name, ctx->config.arg);
}
syslog(
LOG_DAEMON | LOG_INFO,
"telnetd: releasing connection from %s on %s",
session->peername,
path
);
rtems_pty_close_socket(&session->pty);
rtems_mutex_lock(&ctx->mtx);
LIST_INSERT_HEAD(&ctx->free_sessions, session, link);
rtems_mutex_unlock(&ctx->mtx);
}
}
static void telnetd_sleep_after_error(void)
{
/* If something went wrong, sleep for some time */
rtems_task_wake_after(10 * rtems_clock_get_ticks_per_second());
}
static void telnetd_server_task(rtems_task_argument arg)
{
telnetd_context *ctx;
ctx = (telnetd_context *) arg;
while (true) {
telnetd_address peer;
socklen_t address_len;
int session_socket;
telnetd_session *session;
address_len = sizeof(peer.sin);
session_socket = accept(ctx->server_socket, &peer.sa, &address_len);
if (session_socket < 0) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot accept session");
telnetd_sleep_after_error();
continue;
};
rtems_mutex_lock(&ctx->mtx);
session = LIST_FIRST(&ctx->free_sessions);
if (session == NULL) {
rtems_mutex_unlock(&ctx->mtx);
(void)close(session_socket);
syslog(LOG_DAEMON | LOG_ERR, "telnetd: no free session available");
telnetd_sleep_after_error();
continue;
}
LIST_REMOVE(session, link);
rtems_mutex_unlock(&ctx->mtx);
rtems_pty_set_socket(&session->pty, session_socket);
if (
inet_ntop(
AF_INET,
&peer.sin.sin_addr,
session->peername,
sizeof(session->peername)
) == NULL
) {
strlcpy(session->peername, "<UNKNOWN>", sizeof(session->peername));
}
(void)rtems_event_system_send(session->task_id, RTEMS_EVENT_SYSTEM_SERVER);
}
}
static void telnetd_destroy_context(telnetd_context *ctx)
{
telnetd_session *session;
LIST_FOREACH(session, &ctx->free_sessions, link) {
if (session->task_id != 0) {
(void)rtems_task_delete(session->task_id);
}
(void)unlink(rtems_pty_get_path(&session->pty));
}
if (ctx->server_socket >= 0) {
(void)close(ctx->server_socket);
}
rtems_mutex_destroy(&ctx->mtx);
free(ctx);
}
static rtems_status_code telnetd_create_server_socket(telnetd_context *ctx)
{
telnetd_address srv;
socklen_t address_len;
int enable;
ctx->server_socket = socket(PF_INET, SOCK_STREAM, 0);
if (ctx->server_socket < 0) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create server socket");
return RTEMS_UNSATISFIED;
}
enable = 1;
(void)setsockopt(
ctx->server_socket,
SOL_SOCKET,
SO_KEEPALIVE,
&enable,
sizeof(enable)
);
memset(&srv, 0, sizeof(srv));
srv.sin.sin_family = AF_INET;
srv.sin.sin_port = htons(ctx->config.port);
address_len = sizeof(srv.sin);
if (bind(ctx->server_socket, &srv.sa, address_len) != 0) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot bind server socket");
return RTEMS_RESOURCE_IN_USE;
};
if (listen(ctx->server_socket, ctx->config.client_maximum) != 0) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot listen on server socket");
return RTEMS_UNSATISFIED;
};
return RTEMS_SUCCESSFUL;
}
static rtems_status_code telnetd_create_session_tasks(telnetd_context *ctx)
{
uint16_t i;
ctx->task_id = rtems_task_self();
for (i = 0; i < ctx->config.client_maximum; ++i) {
telnetd_session *session;
rtems_status_code sc;
const char *path;
rtems_event_set events;
session = &ctx->sessions[i];
session->ctx = ctx;
rtems_mutex_init(&ctx->mtx, "Telnet");
LIST_INSERT_HEAD(&ctx->free_sessions, session, link);
sc = rtems_task_create(
rtems_build_name('T', 'N', 'T', 'a' + i % 26),
ctx->config.priority,
ctx->config.stack_size,
RTEMS_DEFAULT_MODES,
RTEMS_FLOATING_POINT,
&session->task_id
);
if (sc != RTEMS_SUCCESSFUL) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create session task");
return RTEMS_UNSATISFIED;
}
path = rtems_pty_initialize(&session->pty, i);
if (path == NULL) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create session PTY");
return RTEMS_UNSATISFIED;
}
(void)rtems_task_start(
session->task_id,
telnetd_session_task,
(rtems_task_argument) session
);
(void)rtems_event_receive(
TELNETD_EVENT_SUCCESS | TELNETD_EVENT_ERROR,
RTEMS_WAIT | RTEMS_EVENT_ANY,
RTEMS_NO_TIMEOUT,
&events
);
if ((events & TELNETD_EVENT_ERROR) != 0) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot initialize session task");
return RTEMS_UNSATISFIED;
}
}
return RTEMS_SUCCESSFUL;
}
rtems_status_code rtems_telnetd_start(const rtems_telnetd_config_table* config)
{
telnetd_context *ctx;
rtems_status_code sc;
uint16_t client_maximum;
if (config->command == NULL) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: configuration with invalid command");
return RTEMS_INVALID_ADDRESS;
}
if (config->client_maximum == 0) {
client_maximum = 5;
} else {
client_maximum = config->client_maximum;
}
ctx = calloc(
1,
sizeof(*ctx) + client_maximum * sizeof(ctx->sessions[0])
);
if (ctx == NULL) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot allocate server context");
return RTEMS_UNSATISFIED;
}
ctx->config = *config;
ctx->config.client_maximum = client_maximum;
ctx->server_socket = -1;
LIST_INIT(&ctx->free_sessions);
/* Check priority */
#ifdef RTEMS_NETWORKING
if (ctx->config.priority == 0) {
ctx->config.priority = rtems_bsdnet_config.network_task_priority;
}
#endif
if (ctx->config.priority == 0) {
ctx->config.priority = 100;
}
/* Check stack size */
if (ctx->config.stack_size == 0) {
ctx->config.stack_size = (size_t)32 * 1024;
}
if (ctx->config.port == 0) {
ctx->config.port = 23;
}
sc = telnetd_create_server_socket(ctx);
if (sc != RTEMS_SUCCESSFUL) {
telnetd_destroy_context(ctx);
return sc;
}
sc = telnetd_create_session_tasks(ctx);
if (sc != RTEMS_SUCCESSFUL) {
telnetd_destroy_context(ctx);
return sc;
}
sc = rtems_task_create(
rtems_build_name('T', 'N', 'T', 'D'),
ctx->config.priority,
RTEMS_MINIMUM_STACK_SIZE,
RTEMS_DEFAULT_MODES,
RTEMS_FLOATING_POINT,
&ctx->task_id
);
if (sc != RTEMS_SUCCESSFUL) {
syslog(LOG_DAEMON | LOG_ERR, "telnetd: cannot create server task");
telnetd_destroy_context(ctx);
return RTEMS_UNSATISFIED;
}
(void)rtems_task_start(
ctx->task_id,
telnetd_server_task,
(rtems_task_argument) ctx
);
syslog(
LOG_DAEMON | LOG_INFO,
"telnetd: started successfully on port %" PRIu16, ctx->config.port
);
return RTEMS_SUCCESSFUL;
}