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nuttx-apps/netutils/telnetd/telnetd_daemon.c

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/****************************************************************************
* netutils/telnetd/telnetd_daemon.c
*
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name Gregory Nutt nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <semaphore.h>
#include <sched.h>
#include <errno.h>
#include <debug.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <nuttx/net/telnet.h>
#include <apps/netutils/telnetd.h>
#include <apps/netutils/netlib.h>
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure represents the overall state of one telnet daemon instance
* (Yes, multiple telnet daemons are supported).
*/
struct telnetd_s
{
int port; /* The port to listen on (in network byte order) */
int priority; /* The execution priority of the spawned task, */
int stacksize; /* The stack size needed by the spawned task */
main_t entry; /* The entrypoint of the task to spawn when a new
* connection is accepted. */
};
/* This structure is used to passed information to telnet daemon when it
* started. It contains global information visable to all telnet daemons.
*/
struct telnetd_common_s
{
uint8_t ndaemons; /* The total number of daemons running */
sem_t startsem; /* Enforces one-at-a-time startup */
FAR struct telnetd_s *daemon; /* Describes the new daemon */
};
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/* This structure is used to passed information to telnet daemon when it
* started.
*/
static struct telnetd_common_s g_telnetdcommon;
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: telnetd_daemon
*
* Description:
* This function is the Telnet daemon. It does not return (unless an
* error occurs).
*
* Parameters:
* Standard task start up arguments.
*
* Return:
* Does not return unless an error occurs.
*
****************************************************************************/
static int telnetd_daemon(int argc, char *argv[])
{
FAR struct telnetd_s *daemon;
struct sockaddr_in myaddr;
struct telnet_session_s session;
#ifdef CONFIG_NET_SOLINGER
struct linger ling;
#endif
#ifdef CONFIG_SCHED_HAVE_PARENT
struct sigaction sa;
sigset_t blockset;
#endif
socklen_t addrlen;
pid_t pid;
int listensd;
int acceptsd;
int drvrfd;
#ifdef CONFIG_NET_HAVE_REUSEADDR
int optval;
#endif
int ret;
int fd;
/* Get daemon startup info */
daemon = g_telnetdcommon.daemon;
g_telnetdcommon.daemon = NULL;
sem_post(&g_telnetdcommon.startsem);
DEBUGASSERT(daemon != NULL);
#ifdef CONFIG_SCHED_HAVE_PARENT
/* Call sigaction with the SA_NOCLDWAIT flag so that we do not transform
* children into "zombies" when they terminate: Child exit status will
* not be retained.
*
* NOTE: If the SA_NOCLDWAIT flag is set when establishing a handler for
* SIGCHLD, POSIX.1 leaves it unspecified whether a SIGCHLD signal is
* generated when a child process terminates. On both Linux and NuttX, a
* SIGCHLD signal will be generated in this case.
*/
sa.sa_handler = SIG_IGN;
sa.sa_flags = SA_NOCLDWAIT;
if (sigaction(SIGCHLD, &sa, NULL) < 0)
{
int errval = errno;
ndbg("ERROR: sigaction failed: %d\n", errval);
return -errval;
}
/* Block receipt of the SIGCHLD signal */
sigemptyset(&blockset);
sigaddset(&blockset, SIGCHLD);
if (sigprocmask(SIG_BLOCK, &blockset, NULL) < 0)
{
int errval = errno;
ndbg("ERROR: sigprocmask failed: %d\n", errval);
return -errval;
}
#endif /* CONFIG_SCHED_HAVE_PARENT */
/* Create a new TCP socket to use to listen for connections */
listensd = socket(PF_INET, SOCK_STREAM, 0);
if (listensd < 0)
{
int errval = errno;
ndbg("ERROR: socket failure: %d\n", errval);
return -errval;
}
/* Set socket to reuse address */
#ifdef CONFIG_NET_HAVE_REUSEADDR
optval = 1;
if (setsockopt(listensd, SOL_SOCKET, SO_REUSEADDR, (void*)&optval, sizeof(int)) < 0)
{
ndbg("ERROR: setsockopt SO_REUSEADDR failure: %d\n", errno);
goto errout_with_socket;
}
#endif
/* Bind the socket to a local address */
myaddr.sin_family = AF_INET;
myaddr.sin_port = daemon->port;
myaddr.sin_addr.s_addr = INADDR_ANY;
if (bind(listensd, (struct sockaddr*)&myaddr, sizeof(struct sockaddr_in)) < 0)
{
ndbg("ERROR: bind failure: %d\n", errno);
goto errout_with_socket;
}
/* Listen for connections on the bound TCP socket */
if (listen(listensd, 5) < 0)
{
ndbg("ERROR: listen failure %d\n", errno);
goto errout_with_socket;
}
/* Now go silent. Only the lldbg family of debug functions should
* be used after this point because these do not depend on stdout
* being available.
*/
#ifndef CONFIG_DEBUG
close(0);
close(1);
close(2);
#endif
/* Begin accepting connections */
for (;;)
{
nllvdbg("Accepting connections on port %d\n", ntohs(daemon->port));
addrlen = sizeof(struct sockaddr_in);
acceptsd = accept(listensd, (struct sockaddr*)&myaddr, &addrlen);
if (acceptsd < 0)
{
/* Accept failed */
int errval = errno;
/* Just continue if a signal was received */
if (errval == EINTR)
{
continue;
}
else
{
nlldbg("ERROR: accept failed: %d\n", errval);
goto errout_with_socket;
}
}
/* Configure to "linger" until all data is sent when the socket is closed */
#ifdef CONFIG_NET_SOLINGER
ling.l_onoff = 1;
ling.l_linger = 30; /* timeout is seconds */
if (setsockopt(acceptsd, SOL_SOCKET, SO_LINGER, &ling, sizeof(struct linger)) < 0)
{
nlldbg("ERROR: setsockopt failed: %d\n", errno);
goto errout_with_acceptsd;
}
#endif
/* Open the Telnet factory */
fd = open("/dev/telnet", O_RDONLY);
if (fd < 0)
{
nlldbg("ERROR: open(/dev/telnet) failed: %d\n", errno);
goto errout_with_acceptsd;
}
/* Create a character device to "wrap" the accepted socket descriptor */
nllvdbg("Creating the telnet driver\n");
session.ts_sd = acceptsd;
session.ts_devpath[0] = '\0';
ret = ioctl(fd, SIOCTELNET, (unsigned long)((uintptr_t)&session));
close(fd);
if (ret < 0)
{
nlldbg("ERROR: open(/dev/telnet) failed: %d\n", errno);
goto errout_with_acceptsd;
}
/* Open the driver */
nllvdbg("Opening the telnet driver at %s\n", session.ts_devpath);
drvrfd = open(session.ts_devpath, O_RDWR);
if (drvrfd < 0)
{
nlldbg("ERROR: Failed to open %s: %d\n", session.ts_devpath, errno);
goto errout_with_acceptsd;
}
/* Use this driver as stdin, stdout, and stderror */
(void)dup2(drvrfd, 0);
(void)dup2(drvrfd, 1);
(void)dup2(drvrfd, 2);
/* And we can close our original driver fd */
if (drvrfd > 2)
{
close(drvrfd);
}
/* Create a task to handle the connection. The created task
* will inherit the new stdin, stdout, and stderr.
*/
nllvdbg("Starting the telnet session\n");
pid = task_create("Telnet session", daemon->priority, daemon->stacksize,
daemon->entry, NULL);
if (pid < 0)
{
nlldbg("ERROR: Failed start the telnet session: %d\n", errno);
goto errout_with_acceptsd;
}
/* Forget about the connection. */
close(0);
close(1);
close(2);
}
errout_with_acceptsd:
close(acceptsd);
errout_with_socket:
close(listensd);
free(daemon);
return 1;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: telnetd_start
*
* Description:
* Start the telnet daemon.
*
* Parameters:
* config A pointer to a configuration structure that characterizes the
* telnet daemon. This configuration structure may be defined
* on the caller's stack because it is not retained by the
* daemon.
*
* Return:
* The process ID (pid) of the new telnet daemon is returned on
* success; A negated errno is returned if the daemon was not successfully
* started.
*
****************************************************************************/
int telnetd_start(FAR struct telnetd_config_s *config)
{
FAR struct telnetd_s *daemon;
pid_t pid;
int ret;
/* Allocate a state structure for the new daemon */
daemon = (FAR struct telnetd_s *)malloc(sizeof(struct telnetd_s));
if (!daemon)
{
return -ENOMEM;
}
/* Initialize the daemon structure */
daemon->port = config->d_port;
daemon->priority = config->t_priority;
daemon->stacksize = config->t_stacksize;
daemon->entry = config->t_entry;
/* Initialize the common structure if this is the first daemon */
if (g_telnetdcommon.ndaemons < 1)
{
sem_init(&g_telnetdcommon.startsem, 0, 0);
}
/* Then start the new daemon */
g_telnetdcommon.daemon = daemon;
pid = task_create("Telnet daemon", config->d_priority, config->d_stacksize,
telnetd_daemon, NULL);
if (pid < 0)
{
int errval = errno;
free(daemon);
ndbg("ERROR: Failed to start the telnet daemon: %d\n", errval);
return -errval;
}
/* Then wait for the daemon to start and complete the handshake */
do
{
ret = sem_wait(&g_telnetdcommon.startsem);
/* The only expected error condition is for sem_wait to be awakened by
* a receipt of a signal.
*/
if (ret < 0)
{
DEBUGASSERT(errno == -EINTR);
}
}
while (ret < 0);
/* Return success */
return pid;
}
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