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nuttx/drivers/net/telnet.c

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/****************************************************************************
* drivers/net/telnet.c
*
* Copyright (C) 2007, 2009, 2011-2013 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* This is a leverage of similar logic from uIP which has a compatible BSD
* license:
*
* Author: Adam Dunkels <adam@sics.se>
* Copyright (c) 2003, Adam Dunkels.
* All rights reserved.
*
* 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 of the Institute, NuttX 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 INSTITUTE 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 INSTITUTE 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/stat.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <semaphore.h>
#include <string.h>
#include <poll.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/fs/fs.h>
#include <nuttx/net/net.h>
#include <nuttx/net/telnet.h>
#ifdef CONFIG_NETDEV_TELNET
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
#ifndef CONFIG_TELNET_RXBUFFER_SIZE
# define CONFIG_TELNET_RXBUFFER_SIZE 256
#endif
#ifndef CONFIG_TELNET_TXBUFFER_SIZE
# define CONFIG_TELNET_TXBUFFER_SIZE 256
#endif
/* Telnet protocol stuff ****************************************************/
#define ISO_nl 0x0a
#define ISO_cr 0x0d
#define TELNET_IAC 255
#define TELNET_WILL 251
#define TELNET_WONT 252
#define TELNET_DO 253
#define TELNET_DONT 254
/* Device stuff *************************************************************/
#define TELNETD_DEVFMT "/dev/telnet%d"
/****************************************************************************
* Private Types
****************************************************************************/
/* The state of the telnet parser */
enum telnet_state_e
{
STATE_NORMAL = 0,
STATE_IAC,
STATE_WILL,
STATE_WONT,
STATE_DO,
STATE_DONT
};
/* This structure describes the internal state of the driver */
struct telnet_dev_s
{
sem_t td_exclsem; /* Enforces mutually exclusive access */
uint8_t td_state; /* (See telnet_state_e) */
uint8_t td_pending; /* Number of valid, pending bytes in the rxbuffer */
uint8_t td_offset; /* Offset to the valid, pending bytes in the rxbuffer */
uint8_t td_crefs; /* The number of open references to the session */
int td_minor; /* Minor device number */
FAR struct socket td_psock; /* A clone of the internal socket structure */
char td_rxbuffer[CONFIG_TELNET_RXBUFFER_SIZE];
char td_txbuffer[CONFIG_TELNET_TXBUFFER_SIZE];
};
/* This structure contains global information visable to all telnet driver
* instances.
*/
struct telnet_common_s
{
sem_t tc_exclsem; /* Enforces exclusive access to 'minor' */
uint16_t tc_minor; /* The next minor number to use */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* Support functions */
#ifdef CONFIG_TELNET_DUMPBUFFER
static inline void telnet_dumpbuffer(FAR const char *msg,
FAR const char *buffer, unsigned int nbytes);
#else
# define telnet_dumpbuffer(msg,buffer,nbytes)
#endif
static void telnet_getchar(FAR struct telnet_dev_s *priv, uint8_t ch,
FAR char *dest, int *nread);
static ssize_t telnet_receive(FAR struct telnet_dev_s *priv,
FAR const char *src, size_t srclen, FAR char *dest,
size_t destlen);
static bool telnet_putchar(FAR struct telnet_dev_s *priv, uint8_t ch,
int *nwritten);
static void telnet_sendopt(FAR struct telnet_dev_s *priv, uint8_t option,
uint8_t value);
/* Telnet character driver methods */
static int telnet_open(FAR struct file *filep);
static int telnet_close(FAR struct file *filep);
static ssize_t telnet_read(FAR struct file *, FAR char *, size_t);
static ssize_t telnet_write(FAR struct file *, FAR const char *, size_t);
/* Telnet session creation */
static int telnet_session(FAR struct telnet_session_s *session);
/* Telnet factory driver methods */
static ssize_t factory_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t factory_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int common_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_telnet_fops =
{
telnet_open, /* open */
telnet_close, /* close */
telnet_read, /* read */
telnet_write, /* write */
0, /* seek */
common_ioctl /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, 0 /* poll */
#endif
};
static const struct file_operations g_factory_fops =
{
0, /* open */
0, /* close */
factory_read, /* read */
factory_write, /* write */
0, /* seek */
common_ioctl /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, 0 /* poll */
#endif
};
/* Global information shared amongst telnet driver instanaces. */
static struct telnet_common_s g_telnet_common =
{
SEM_INITIALIZER(1),
0
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: telnet_dumpbuffer
*
* Description:
* Dump a buffer of data (debug only)
*
****************************************************************************/
#ifdef CONFIG_TELNET_DUMPBUFFER
static inline void telnet_dumpbuffer(FAR const char *msg,
FAR const char *buffer,
unsigned int nbytes)
{
/* CONFIG_DEBUG, CONFIG_DEBUG_VERBOSE, and CONFIG_DEBUG_NET have to be
* defined or the following does nothing.
*/
nvdbgdumpbuffer(msg, (FAR const uint8_t*)buffer, nbytes);
}
#endif
/****************************************************************************
* Name: telnet_getchar
*
* Description:
* Get another character for the user received buffer from the RX buffer
*
****************************************************************************/
static void telnet_getchar(FAR struct telnet_dev_s *priv, uint8_t ch,
FAR char *dest, int *nread)
{
register int index;
/* Ignore carriage returns */
if (ch != ISO_cr)
{
/* Add all other characters to the destination buffer */
index = *nread;
dest[index++] = ch;
*nread = index;
}
}
/****************************************************************************
* Name: telnet_receive
*
* Description:
* Process a received Telnet buffer
*
****************************************************************************/
static ssize_t telnet_receive(FAR struct telnet_dev_s *priv, FAR const char *src,
size_t srclen, FAR char *dest, size_t destlen)
{
int nread;
uint8_t ch;
nllvdbg("srclen: %d destlen: %d\n", srclen, destlen);
for (nread = 0; srclen > 0 && nread < destlen; srclen--)
{
ch = *src++;
nllvdbg("ch=%02x state=%d\n", ch, priv->td_state);
switch (priv->td_state)
{
case STATE_IAC:
if (ch == TELNET_IAC)
{
telnet_getchar(priv, ch, dest, &nread);
priv->td_state = STATE_NORMAL;
}
else
{
switch (ch)
{
case TELNET_WILL:
priv->td_state = STATE_WILL;
break;
case TELNET_WONT:
priv->td_state = STATE_WONT;
break;
case TELNET_DO:
priv->td_state = STATE_DO;
break;
case TELNET_DONT:
priv->td_state = STATE_DONT;
break;
default:
priv->td_state = STATE_NORMAL;
break;
}
}
break;
case STATE_WILL:
/* Reply with a DONT */
telnet_sendopt(priv, TELNET_DONT, ch);
priv->td_state = STATE_NORMAL;
break;
case STATE_WONT:
/* Reply with a DONT */
telnet_sendopt(priv, TELNET_DONT, ch);
priv->td_state = STATE_NORMAL;
break;
case STATE_DO:
/* Reply with a WONT */
telnet_sendopt(priv, TELNET_WONT, ch);
priv->td_state = STATE_NORMAL;
break;
case STATE_DONT:
/* Reply with a WONT */
telnet_sendopt(priv, TELNET_WONT, ch);
priv->td_state = STATE_NORMAL;
break;
case STATE_NORMAL:
if (ch == TELNET_IAC)
{
priv->td_state = STATE_IAC;
}
else
{
telnet_getchar(priv, ch, dest, &nread);
}
break;
}
}
/* We get here if (1) all of the received bytes have been processed, or
* (2) if the user's buffer has become full.
*/
if (srclen > 0)
{
/* Remember where we left off. These bytes will be returned the next
* time that telnet_read() is called.
*/
priv->td_pending = srclen;
priv->td_offset = (src - priv->td_rxbuffer);
}
else
{
/* All of the received bytes were consumed */
priv->td_pending = 0;
priv->td_offset = 0;
}
return nread;
}
/****************************************************************************
* Name: telnet_putchar
*
* Description:
* Put another character from the user buffer to the TX buffer.
*
****************************************************************************/
static bool telnet_putchar(FAR struct telnet_dev_s *priv, uint8_t ch,
int *nread)
{
register int index;
bool ret = false;
/* Ignore carriage returns (we will put these in automatically as necesary) */
if (ch != ISO_cr)
{
/* Add all other characters to the destination buffer */
index = *nread;
priv->td_txbuffer[index++] = ch;
/* Check for line feeds */
if (ch == ISO_nl)
{
/* Now add the carriage return */
priv->td_txbuffer[index++] = ISO_cr;
priv->td_txbuffer[index++] = '\0';
/* End of line */
ret = true;
}
*nread = index;
}
return ret;
}
/****************************************************************************
* Name: telnet_sendopt
*
* Description:
* Send the telnet option bytes
*
****************************************************************************/
static void telnet_sendopt(FAR struct telnet_dev_s *priv, uint8_t option,
uint8_t value)
{
uint8_t optbuf[4];
optbuf[0] = TELNET_IAC;
optbuf[1] = option;
optbuf[2] = value;
optbuf[3] = 0;
telnet_dumpbuffer("Send optbuf", optbuf, 4);
if (psock_send(&priv->td_psock, optbuf, 4, 0) < 0)
{
nlldbg("Failed to send TELNET_IAC\n");
}
}
/****************************************************************************
* Name: telnet_open
****************************************************************************/
static int telnet_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
int tmp;
int ret;
nllvdbg("td_crefs: %d\n", priv->td_crefs);
/* O_NONBLOCK is not supported */
if (filep->f_oflags & O_NONBLOCK)
{
ret = -ENOSYS;
goto errout;
}
/* Get exclusive access to the device structures */
ret = sem_wait(&priv->td_exclsem);
if (ret < 0)
{
ret = -errno;
goto errout;
}
/* Increment the count of references to the device. If this the first
* time that the driver has been opened for this device, then initialize
* the device.
*/
tmp = priv->td_crefs + 1;
if (tmp > 255)
{
/* More than 255 opens; uint8_t would overflow to zero */
ret = -EMFILE;
goto errout_with_sem;
}
/* Save the new open count on success */
priv->td_crefs = tmp;
ret = OK;
errout_with_sem:
sem_post(&priv->td_exclsem);
errout:
return ret;
}
/****************************************************************************
* Name: telnet_close
****************************************************************************/
static int telnet_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
FAR char *devpath;
int ret;
nllvdbg("td_crefs: %d\n", priv->td_crefs);
/* Get exclusive access to the device structures */
ret = sem_wait(&priv->td_exclsem);
if (ret < 0)
{
ret = -errno;
goto errout;
}
/* Decrement the references to the driver. If the reference count will
* decrement to 0, then uninitialize the driver.
*/
if (priv->td_crefs > 1)
{
/* Just decrement the reference count and release the semaphore */
priv->td_crefs--;
sem_post(&priv->td_exclsem);
}
else
{
/* Re-create the path to the driver. */
sched_lock();
ret = asprintf(&devpath, TELNETD_DEVFMT, priv->td_minor);
if (ret < 0)
{
nlldbg("ERROR: Failed to allocate the driver path\n");
}
else
{
/* Un-register the character driver */
ret = unregister_driver(devpath);
if (ret < 0)
{
/* NOTE: a return value of -EBUSY is not an error, it simply
* means that the Telnet driver is busy now and cannot be
* registered now because there are other sessions using the
* connection. The driver will be properly unregistered when
* the final session terminates.
*/
if (ret != -EBUSY)
{
nlldbg("Failed to unregister the driver %s: %d\n",
devpath, ret);
}
}
free(devpath);
}
/* Close the socket */
psock_close(&priv->td_psock);
/* Release the driver memory. What if there are threads waiting on
* td_exclsem? They will never be awakened! How could this happen?
* crefs == 1 so there are no other open references to the driver.
* But this could have if someone were trying to re-open the driver
* after every other thread has closed it. That really should not
* happen in the intended usage model.
*/
DEBUGASSERT(priv->td_exclsem.semcount == 0);
sem_destroy(&priv->td_exclsem);
free(priv);
sched_unlock();
}
ret = OK;
errout:
return ret;
}
/****************************************************************************
* Name: telnet_read
****************************************************************************/
static ssize_t telnet_read(FAR struct file *filep, FAR char *buffer, size_t len)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
ssize_t ret;
nllvdbg("len: %d\n", len);
/* First, handle the case where there are still valid bytes left in the
* I/O buffer from the last time that read was called. NOTE: Much of
* what we read may be protocol stuff and may not correspond to user
* data. Hence we need the loop and we need may need to call psock_recv()
* multiple times in order to get data that the client is interested in.
*/
do
{
if (priv->td_pending > 0)
{
/* Process the buffered telnet data */
FAR const char *src = &priv->td_rxbuffer[priv->td_offset];
ret = telnet_receive(priv, src, priv->td_pending, buffer, len);
}
/* Read a buffer of data from the telnet client */
else
{
ret = psock_recv(&priv->td_psock, priv->td_rxbuffer,
CONFIG_TELNET_RXBUFFER_SIZE, 0);
/* Did we receive anything? */
if (ret > 0)
{
/* Yes.. Process the newly received telnet data */
telnet_dumpbuffer("Received buffer", priv->td_rxbuffer, ret);
ret = telnet_receive(priv, priv->td_rxbuffer, ret, buffer, len);
}
/* Otherwise the peer closed the connection (ret == 0) or an error
* occurred (ret < 0).
*/
else
{
break;
}
}
}
while (ret == 0);
/* Return:
*
* ret > 0: The number of characters copied into the user buffer by
* telnet_receive().
* ret <= 0: Loss of connection or error events reported by recv().
*/
return ret;
}
/****************************************************************************
* Name: telnet_write
****************************************************************************/
static ssize_t telnet_write(FAR struct file *filep, FAR const char *buffer, size_t len)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
FAR const char *src = buffer;
ssize_t nsent;
ssize_t ret;
int ncopied;
char ch;
bool eol;
nllvdbg("len: %d\n", len);
/* Process each character from the user buffer */
for (nsent = 0, ncopied = 0; nsent < len; nsent++)
{
/* Get the next character from the user buffer */
ch = *src++;
/* Add the character to the TX buffer */
eol = telnet_putchar(priv, ch, &ncopied);
/* Was that the end of a line? Or is the buffer too full to hold the
* next largest character sequence ("\r\n\0")?
*/
if (eol || ncopied > CONFIG_TELNET_TXBUFFER_SIZE-3)
{
/* Yes... send the data now */
ret = psock_send(&priv->td_psock, priv->td_txbuffer, ncopied, 0);
if (ret < 0)
{
nlldbg("psock_send failed '%s': %d\n", priv->td_txbuffer, ret);
return ret;
}
/* Reset the index to the beginning of the TX buffer. */
ncopied = 0;
}
}
/* Send anything remaining in the TX buffer */
if (ncopied > 0)
{
ret = psock_send(&priv->td_psock, priv->td_txbuffer, ncopied, 0);
if (ret < 0)
{
nlldbg("psock_send failed '%s': %d\n", priv->td_txbuffer, ret);
return ret;
}
}
/* Notice that we don't actually return the number of bytes sent, but
* rather, the number of bytes that the caller asked us to send. We may
* have sent more bytes (because of CR-LF expansion and because of NULL
* termination). But it confuses some logic if you report that you sent
* more than you were requested to.
*/
return len;
}
/****************************************************************************
* Name: telnet_session
*
* Description:
* Create a character driver to "wrap" the telnet session. This function
* will select and return a unique path for the new telnet device.
*
* Parameters:
* session - On input, contains the socket descriptor that represents the
* new telnet connection. On output, it holds the path to the new Telnet driver.
*
* Return:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
static int telnet_session(FAR struct telnet_session_s *session)
{
FAR struct telnet_dev_s *priv;
FAR struct socket *psock;
struct stat statbuf;
uint16_t start;
int ret;
/* Allocate instance data for this driver */
priv = (FAR struct telnet_dev_s*)malloc(sizeof(struct telnet_dev_s));
if (!priv)
{
nlldbg("Failed to allocate the driver data structure\n");
return -ENOMEM;
}
/* Initialize the allocated driver instance */
sem_init(&priv->td_exclsem, 0, 1);
priv->td_state = STATE_NORMAL;
priv->td_crefs = 0;
priv->td_pending = 0;
priv->td_offset = 0;
/* Clone the internal socket structure. We do this so that it will be
* independent of threads and of socket descriptors (the original socket
* instance resided in the daemon's task group`).
*/
psock = sockfd_socket(session->ts_sd);
if (!psock)
{
nlldbg("Failed to convert sd=%d to a socket structure\n", session->ts_sd);
ret = -EINVAL;
goto errout_with_dev;
}
ret = net_clone(psock, &priv->td_psock);
if (ret < 0)
{
nlldbg("net_clone failed: %d\n", ret);
goto errout_with_dev;
}
/* Allocate a unique minor device number of the telnet drvier.
* Get exclusive access to the minor counter.
*/
do
{
ret = sem_wait(&g_telnet_common.tc_exclsem);
if (ret < 0 && errno != -EINTR)
{
goto errout_with_clone;
}
}
while (ret < 0);
/* Loop until the device name is verified to be unique. */
start = g_telnet_common.tc_minor;
do
{
/* Get the next candiate minor number */
priv->td_minor = g_telnet_common.tc_minor;
g_telnet_common.tc_minor++;
snprintf(session->ts_devpath, TELNET_DEVPATH_MAX, TELNETD_DEVFMT,
priv->td_minor);
ret = stat(session->ts_devpath, &statbuf);
DEBUGASSERT(ret >= 0 || errno == ENOENT);
}
while (ret >= 0 && start != g_telnet_common.tc_minor);
if (ret >= 0)
{
nlldbg("ERROR: Too many sessions\n");
ret = -ENFILE;
goto errout_with_semaphore;
}
/* Register the driver */
ret = register_driver(session->ts_devpath, &g_telnet_fops, 0666, priv);
if (ret < 0)
{
nlldbg("ERROR: Failed to register the driver %s: %d\n",
session->ts_devpath, ret);
goto errout_with_semaphore;
}
/* Close the original psoock (keeping the clone) */
psock_close(psock);
/* Return the path to the new telnet driver */
sem_post(&g_telnet_common.tc_exclsem);
return OK;
errout_with_semaphore:
sem_post(&g_telnet_common.tc_exclsem);
errout_with_clone:
psock_close(&priv->td_psock);
errout_with_dev:
free(priv);
return ret;
}
/****************************************************************************
* Name: factory_read
****************************************************************************/
static ssize_t factory_read(FAR struct file *filep, FAR char *buffer,
size_t len)
{
return 0; /* Return EOF */
}
/****************************************************************************
* Name: factory_write
****************************************************************************/
static ssize_t factory_write(FAR struct file *filep, FAR const char *buffer,
size_t len)
{
return len; /* Say that everything was written */
}
/****************************************************************************
* Name: common_ioctl
****************************************************************************/
static int common_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
int ret;
switch (cmd)
{
/* Command: SIOCTELNET
* Description: Create a Telnet sessions.
* Argument: A pointer to a write-able instance of struct
* telnet_session_s.
* Dependencies: CONFIG_NETDEV_TELNET
*/
case SIOCTELNET:
{
FAR struct telnet_session_s *session =
(FAR struct telnet_session_s *)((uintptr_t)arg);
if (session == NULL)
{
ret = -EINVAL;
}
else
{
ret = telnet_session(session);
}
}
break;
default:
ret = -ENOTTY;
break;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: telnet_initialize
*
* Description:
* Create the Telnet factory at /dev/telnet.
*
* Parameters:
* None
*
* Return:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
int telnet_initialize(void)
{
return register_driver("/dev/telnet", &g_factory_fops, 0666, NULL);
}
#endif /* CONFIG_NETDEV_TELNET */
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