/*
|
* PPP async serial channel driver for Linux.
|
*
|
* Copyright 1999 Paul Mackerras.
|
*
|
* This program is free software; you can redistribute it and/or
|
* modify it under the terms of the GNU General Public License
|
* as published by the Free Software Foundation; either version
|
* 2 of the License, or (at your option) any later version.
|
*
|
* This driver provides the encapsulation and framing for sending
|
* and receiving PPP frames over async serial lines. It relies on
|
* the generic PPP layer to give it frames to send and to process
|
* received frames. It implements the PPP line discipline.
|
*
|
* Part of the code in this driver was inspired by the old async-only
|
* PPP driver, written by Michael Callahan and Al Longyear, and
|
* subsequently hacked by Paul Mackerras.
|
*/
|
|
#include <linux/module.h>
|
#include <linux/kernel.h>
|
#include <linux/skbuff.h>
|
#include <linux/tty.h>
|
#include <linux/netdevice.h>
|
#include <linux/poll.h>
|
#include <linux/crc-ccitt.h>
|
#include <linux/ppp_defs.h>
|
#include <linux/ppp-ioctl.h>
|
#include <linux/ppp_channel.h>
|
#include <linux/spinlock.h>
|
#include <linux/init.h>
|
#include <linux/interrupt.h>
|
#include <linux/jiffies.h>
|
#include <linux/slab.h>
|
#include <asm/unaligned.h>
|
#include <linux/uaccess.h>
|
#include <asm/string.h>
|
|
#define PPP_VERSION "2.4.2"
|
|
#define OBUFSIZE 4096
|
|
/* Structure for storing local state. */
|
struct asyncppp {
|
struct tty_struct *tty;
|
unsigned int flags;
|
unsigned int state;
|
unsigned int rbits;
|
int mru;
|
spinlock_t xmit_lock;
|
spinlock_t recv_lock;
|
unsigned long xmit_flags;
|
u32 xaccm[8];
|
u32 raccm;
|
unsigned int bytes_sent;
|
unsigned int bytes_rcvd;
|
|
struct sk_buff *tpkt;
|
int tpkt_pos;
|
u16 tfcs;
|
unsigned char *optr;
|
unsigned char *olim;
|
unsigned long last_xmit;
|
|
struct sk_buff *rpkt;
|
int lcp_fcs;
|
struct sk_buff_head rqueue;
|
|
struct tasklet_struct tsk;
|
|
refcount_t refcnt;
|
struct semaphore dead_sem;
|
struct ppp_channel chan; /* interface to generic ppp layer */
|
unsigned char obuf[OBUFSIZE];
|
};
|
|
/* Bit numbers in xmit_flags */
|
#define XMIT_WAKEUP 0
|
#define XMIT_FULL 1
|
#define XMIT_BUSY 2
|
|
/* State bits */
|
#define SC_TOSS 1
|
#define SC_ESCAPE 2
|
#define SC_PREV_ERROR 4
|
|
/* Bits in rbits */
|
#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
|
|
static int flag_time = HZ;
|
module_param(flag_time, int, 0);
|
MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)");
|
MODULE_LICENSE("GPL");
|
MODULE_ALIAS_LDISC(N_PPP);
|
|
/*
|
* Prototypes.
|
*/
|
static int ppp_async_encode(struct asyncppp *ap);
|
static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb);
|
static int ppp_async_push(struct asyncppp *ap);
|
static void ppp_async_flush_output(struct asyncppp *ap);
|
static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
|
char *flags, int count);
|
static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd,
|
unsigned long arg);
|
static void ppp_async_process(unsigned long arg);
|
|
static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
|
int len, int inbound);
|
|
static const struct ppp_channel_ops async_ops = {
|
.start_xmit = ppp_async_send,
|
.ioctl = ppp_async_ioctl,
|
};
|
|
/*
|
* Routines implementing the PPP line discipline.
|
*/
|
|
/*
|
* We have a potential race on dereferencing tty->disc_data,
|
* because the tty layer provides no locking at all - thus one
|
* cpu could be running ppp_asynctty_receive while another
|
* calls ppp_asynctty_close, which zeroes tty->disc_data and
|
* frees the memory that ppp_asynctty_receive is using. The best
|
* way to fix this is to use a rwlock in the tty struct, but for now
|
* we use a single global rwlock for all ttys in ppp line discipline.
|
*
|
* FIXME: this is no longer true. The _close path for the ldisc is
|
* now guaranteed to be sane.
|
*/
|
static DEFINE_RWLOCK(disc_data_lock);
|
|
static struct asyncppp *ap_get(struct tty_struct *tty)
|
{
|
struct asyncppp *ap;
|
|
read_lock(&disc_data_lock);
|
ap = tty->disc_data;
|
if (ap != NULL)
|
refcount_inc(&ap->refcnt);
|
read_unlock(&disc_data_lock);
|
return ap;
|
}
|
|
static void ap_put(struct asyncppp *ap)
|
{
|
if (refcount_dec_and_test(&ap->refcnt))
|
up(&ap->dead_sem);
|
}
|
|
/*
|
* Called when a tty is put into PPP line discipline. Called in process
|
* context.
|
*/
|
static int
|
ppp_asynctty_open(struct tty_struct *tty)
|
{
|
struct asyncppp *ap;
|
int err;
|
int speed;
|
|
if (tty->ops->write == NULL)
|
return -EOPNOTSUPP;
|
|
err = -ENOMEM;
|
ap = kzalloc(sizeof(*ap), GFP_KERNEL);
|
if (!ap)
|
goto out;
|
|
/* initialize the asyncppp structure */
|
ap->tty = tty;
|
ap->mru = PPP_MRU;
|
spin_lock_init(&ap->xmit_lock);
|
spin_lock_init(&ap->recv_lock);
|
ap->xaccm[0] = ~0U;
|
ap->xaccm[3] = 0x60000000U;
|
ap->raccm = ~0U;
|
ap->optr = ap->obuf;
|
ap->olim = ap->obuf;
|
ap->lcp_fcs = -1;
|
|
skb_queue_head_init(&ap->rqueue);
|
tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap);
|
|
refcount_set(&ap->refcnt, 1);
|
sema_init(&ap->dead_sem, 0);
|
|
ap->chan.private = ap;
|
ap->chan.ops = &async_ops;
|
ap->chan.mtu = PPP_MRU;
|
speed = tty_get_baud_rate(tty);
|
ap->chan.speed = speed;
|
err = ppp_register_channel(&ap->chan);
|
if (err)
|
goto out_free;
|
|
tty->disc_data = ap;
|
tty->receive_room = 65536;
|
return 0;
|
|
out_free:
|
kfree(ap);
|
out:
|
return err;
|
}
|
|
/*
|
* Called when the tty is put into another line discipline
|
* or it hangs up. We have to wait for any cpu currently
|
* executing in any of the other ppp_asynctty_* routines to
|
* finish before we can call ppp_unregister_channel and free
|
* the asyncppp struct. This routine must be called from
|
* process context, not interrupt or softirq context.
|
*/
|
static void
|
ppp_asynctty_close(struct tty_struct *tty)
|
{
|
struct asyncppp *ap;
|
|
write_lock_irq(&disc_data_lock);
|
ap = tty->disc_data;
|
tty->disc_data = NULL;
|
write_unlock_irq(&disc_data_lock);
|
if (!ap)
|
return;
|
|
/*
|
* We have now ensured that nobody can start using ap from now
|
* on, but we have to wait for all existing users to finish.
|
* Note that ppp_unregister_channel ensures that no calls to
|
* our channel ops (i.e. ppp_async_send/ioctl) are in progress
|
* by the time it returns.
|
*/
|
if (!refcount_dec_and_test(&ap->refcnt))
|
down(&ap->dead_sem);
|
tasklet_kill(&ap->tsk);
|
|
ppp_unregister_channel(&ap->chan);
|
kfree_skb(ap->rpkt);
|
skb_queue_purge(&ap->rqueue);
|
kfree_skb(ap->tpkt);
|
kfree(ap);
|
}
|
|
/*
|
* Called on tty hangup in process context.
|
*
|
* Wait for I/O to driver to complete and unregister PPP channel.
|
* This is already done by the close routine, so just call that.
|
*/
|
static int ppp_asynctty_hangup(struct tty_struct *tty)
|
{
|
ppp_asynctty_close(tty);
|
return 0;
|
}
|
|
/*
|
* Read does nothing - no data is ever available this way.
|
* Pppd reads and writes packets via /dev/ppp instead.
|
*/
|
static ssize_t
|
ppp_asynctty_read(struct tty_struct *tty, struct file *file,
|
unsigned char __user *buf, size_t count)
|
{
|
return -EAGAIN;
|
}
|
|
/*
|
* Write on the tty does nothing, the packets all come in
|
* from the ppp generic stuff.
|
*/
|
static ssize_t
|
ppp_asynctty_write(struct tty_struct *tty, struct file *file,
|
const unsigned char *buf, size_t count)
|
{
|
return -EAGAIN;
|
}
|
|
/*
|
* Called in process context only. May be re-entered by multiple
|
* ioctl calling threads.
|
*/
|
|
static int
|
ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file,
|
unsigned int cmd, unsigned long arg)
|
{
|
struct asyncppp *ap = ap_get(tty);
|
int err, val;
|
int __user *p = (int __user *)arg;
|
|
if (!ap)
|
return -ENXIO;
|
err = -EFAULT;
|
switch (cmd) {
|
case PPPIOCGCHAN:
|
err = -EFAULT;
|
if (put_user(ppp_channel_index(&ap->chan), p))
|
break;
|
err = 0;
|
break;
|
|
case PPPIOCGUNIT:
|
err = -EFAULT;
|
if (put_user(ppp_unit_number(&ap->chan), p))
|
break;
|
err = 0;
|
break;
|
|
case TCFLSH:
|
/* flush our buffers and the serial port's buffer */
|
if (arg == TCIOFLUSH || arg == TCOFLUSH)
|
ppp_async_flush_output(ap);
|
err = n_tty_ioctl_helper(tty, file, cmd, arg);
|
break;
|
|
case FIONREAD:
|
val = 0;
|
if (put_user(val, p))
|
break;
|
err = 0;
|
break;
|
|
default:
|
/* Try the various mode ioctls */
|
err = tty_mode_ioctl(tty, file, cmd, arg);
|
}
|
|
ap_put(ap);
|
return err;
|
}
|
|
/* No kernel lock - fine */
|
static __poll_t
|
ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
|
{
|
return 0;
|
}
|
|
/* May sleep, don't call from interrupt level or with interrupts disabled */
|
static void
|
ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
|
char *cflags, int count)
|
{
|
struct asyncppp *ap = ap_get(tty);
|
unsigned long flags;
|
|
if (!ap)
|
return;
|
spin_lock_irqsave(&ap->recv_lock, flags);
|
ppp_async_input(ap, buf, cflags, count);
|
spin_unlock_irqrestore(&ap->recv_lock, flags);
|
if (!skb_queue_empty(&ap->rqueue))
|
tasklet_schedule(&ap->tsk);
|
ap_put(ap);
|
tty_unthrottle(tty);
|
}
|
|
static void
|
ppp_asynctty_wakeup(struct tty_struct *tty)
|
{
|
struct asyncppp *ap = ap_get(tty);
|
|
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
|
if (!ap)
|
return;
|
set_bit(XMIT_WAKEUP, &ap->xmit_flags);
|
tasklet_schedule(&ap->tsk);
|
ap_put(ap);
|
}
|
|
|
static struct tty_ldisc_ops ppp_ldisc = {
|
.owner = THIS_MODULE,
|
.magic = TTY_LDISC_MAGIC,
|
.name = "ppp",
|
.open = ppp_asynctty_open,
|
.close = ppp_asynctty_close,
|
.hangup = ppp_asynctty_hangup,
|
.read = ppp_asynctty_read,
|
.write = ppp_asynctty_write,
|
.ioctl = ppp_asynctty_ioctl,
|
.poll = ppp_asynctty_poll,
|
.receive_buf = ppp_asynctty_receive,
|
.write_wakeup = ppp_asynctty_wakeup,
|
};
|
|
static int __init
|
ppp_async_init(void)
|
{
|
int err;
|
|
err = tty_register_ldisc(N_PPP, &ppp_ldisc);
|
if (err != 0)
|
printk(KERN_ERR "PPP_async: error %d registering line disc.\n",
|
err);
|
return err;
|
}
|
|
/*
|
* The following routines provide the PPP channel interface.
|
*/
|
static int
|
ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
|
{
|
struct asyncppp *ap = chan->private;
|
void __user *argp = (void __user *)arg;
|
int __user *p = argp;
|
int err, val;
|
u32 accm[8];
|
|
err = -EFAULT;
|
switch (cmd) {
|
case PPPIOCGFLAGS:
|
val = ap->flags | ap->rbits;
|
if (put_user(val, p))
|
break;
|
err = 0;
|
break;
|
case PPPIOCSFLAGS:
|
if (get_user(val, p))
|
break;
|
ap->flags = val & ~SC_RCV_BITS;
|
spin_lock_irq(&ap->recv_lock);
|
ap->rbits = val & SC_RCV_BITS;
|
spin_unlock_irq(&ap->recv_lock);
|
err = 0;
|
break;
|
|
case PPPIOCGASYNCMAP:
|
if (put_user(ap->xaccm[0], (u32 __user *)argp))
|
break;
|
err = 0;
|
break;
|
case PPPIOCSASYNCMAP:
|
if (get_user(ap->xaccm[0], (u32 __user *)argp))
|
break;
|
err = 0;
|
break;
|
|
case PPPIOCGRASYNCMAP:
|
if (put_user(ap->raccm, (u32 __user *)argp))
|
break;
|
err = 0;
|
break;
|
case PPPIOCSRASYNCMAP:
|
if (get_user(ap->raccm, (u32 __user *)argp))
|
break;
|
err = 0;
|
break;
|
|
case PPPIOCGXASYNCMAP:
|
if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
|
break;
|
err = 0;
|
break;
|
case PPPIOCSXASYNCMAP:
|
if (copy_from_user(accm, argp, sizeof(accm)))
|
break;
|
accm[2] &= ~0x40000000U; /* can't escape 0x5e */
|
accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */
|
memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
|
err = 0;
|
break;
|
|
case PPPIOCGMRU:
|
if (put_user(ap->mru, p))
|
break;
|
err = 0;
|
break;
|
case PPPIOCSMRU:
|
if (get_user(val, p))
|
break;
|
if (val < PPP_MRU)
|
val = PPP_MRU;
|
ap->mru = val;
|
err = 0;
|
break;
|
|
default:
|
err = -ENOTTY;
|
}
|
|
return err;
|
}
|
|
/*
|
* This is called at softirq level to deliver received packets
|
* to the ppp_generic code, and to tell the ppp_generic code
|
* if we can accept more output now.
|
*/
|
static void ppp_async_process(unsigned long arg)
|
{
|
struct asyncppp *ap = (struct asyncppp *) arg;
|
struct sk_buff *skb;
|
|
/* process received packets */
|
while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
|
if (skb->cb[0])
|
ppp_input_error(&ap->chan, 0);
|
ppp_input(&ap->chan, skb);
|
}
|
|
/* try to push more stuff out */
|
if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_async_push(ap))
|
ppp_output_wakeup(&ap->chan);
|
}
|
|
/*
|
* Procedures for encapsulation and framing.
|
*/
|
|
/*
|
* Procedure to encode the data for async serial transmission.
|
* Does octet stuffing (escaping), puts the address/control bytes
|
* on if A/C compression is disabled, and does protocol compression.
|
* Assumes ap->tpkt != 0 on entry.
|
* Returns 1 if we finished the current frame, 0 otherwise.
|
*/
|
|
#define PUT_BYTE(ap, buf, c, islcp) do { \
|
if ((islcp && c < 0x20) || (ap->xaccm[c >> 5] & (1 << (c & 0x1f)))) {\
|
*buf++ = PPP_ESCAPE; \
|
*buf++ = c ^ PPP_TRANS; \
|
} else \
|
*buf++ = c; \
|
} while (0)
|
|
static int
|
ppp_async_encode(struct asyncppp *ap)
|
{
|
int fcs, i, count, c, proto;
|
unsigned char *buf, *buflim;
|
unsigned char *data;
|
int islcp;
|
|
buf = ap->obuf;
|
ap->olim = buf;
|
ap->optr = buf;
|
i = ap->tpkt_pos;
|
data = ap->tpkt->data;
|
count = ap->tpkt->len;
|
fcs = ap->tfcs;
|
proto = get_unaligned_be16(data);
|
|
/*
|
* LCP packets with code values between 1 (configure-reqest)
|
* and 7 (code-reject) must be sent as though no options
|
* had been negotiated.
|
*/
|
islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
|
|
if (i == 0) {
|
if (islcp)
|
async_lcp_peek(ap, data, count, 0);
|
|
/*
|
* Start of a new packet - insert the leading FLAG
|
* character if necessary.
|
*/
|
if (islcp || flag_time == 0 ||
|
time_after_eq(jiffies, ap->last_xmit + flag_time))
|
*buf++ = PPP_FLAG;
|
ap->last_xmit = jiffies;
|
fcs = PPP_INITFCS;
|
|
/*
|
* Put in the address/control bytes if necessary
|
*/
|
if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
|
PUT_BYTE(ap, buf, 0xff, islcp);
|
fcs = PPP_FCS(fcs, 0xff);
|
PUT_BYTE(ap, buf, 0x03, islcp);
|
fcs = PPP_FCS(fcs, 0x03);
|
}
|
}
|
|
/*
|
* Once we put in the last byte, we need to put in the FCS
|
* and closing flag, so make sure there is at least 7 bytes
|
* of free space in the output buffer.
|
*/
|
buflim = ap->obuf + OBUFSIZE - 6;
|
while (i < count && buf < buflim) {
|
c = data[i++];
|
if (i == 1 && c == 0 && (ap->flags & SC_COMP_PROT))
|
continue; /* compress protocol field */
|
fcs = PPP_FCS(fcs, c);
|
PUT_BYTE(ap, buf, c, islcp);
|
}
|
|
if (i < count) {
|
/*
|
* Remember where we are up to in this packet.
|
*/
|
ap->olim = buf;
|
ap->tpkt_pos = i;
|
ap->tfcs = fcs;
|
return 0;
|
}
|
|
/*
|
* We have finished the packet. Add the FCS and flag.
|
*/
|
fcs = ~fcs;
|
c = fcs & 0xff;
|
PUT_BYTE(ap, buf, c, islcp);
|
c = (fcs >> 8) & 0xff;
|
PUT_BYTE(ap, buf, c, islcp);
|
*buf++ = PPP_FLAG;
|
ap->olim = buf;
|
|
consume_skb(ap->tpkt);
|
ap->tpkt = NULL;
|
return 1;
|
}
|
|
/*
|
* Transmit-side routines.
|
*/
|
|
/*
|
* Send a packet to the peer over an async tty line.
|
* Returns 1 iff the packet was accepted.
|
* If the packet was not accepted, we will call ppp_output_wakeup
|
* at some later time.
|
*/
|
static int
|
ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb)
|
{
|
struct asyncppp *ap = chan->private;
|
|
ppp_async_push(ap);
|
|
if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
|
return 0; /* already full */
|
ap->tpkt = skb;
|
ap->tpkt_pos = 0;
|
|
ppp_async_push(ap);
|
return 1;
|
}
|
|
/*
|
* Push as much data as possible out to the tty.
|
*/
|
static int
|
ppp_async_push(struct asyncppp *ap)
|
{
|
int avail, sent, done = 0;
|
struct tty_struct *tty = ap->tty;
|
int tty_stuffed = 0;
|
|
/*
|
* We can get called recursively here if the tty write
|
* function calls our wakeup function. This can happen
|
* for example on a pty with both the master and slave
|
* set to PPP line discipline.
|
* We use the XMIT_BUSY bit to detect this and get out,
|
* leaving the XMIT_WAKEUP bit set to tell the other
|
* instance that it may now be able to write more now.
|
*/
|
if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
|
return 0;
|
spin_lock_bh(&ap->xmit_lock);
|
for (;;) {
|
if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
|
tty_stuffed = 0;
|
if (!tty_stuffed && ap->optr < ap->olim) {
|
avail = ap->olim - ap->optr;
|
set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
|
sent = tty->ops->write(tty, ap->optr, avail);
|
if (sent < 0)
|
goto flush; /* error, e.g. loss of CD */
|
ap->optr += sent;
|
if (sent < avail)
|
tty_stuffed = 1;
|
continue;
|
}
|
if (ap->optr >= ap->olim && ap->tpkt) {
|
if (ppp_async_encode(ap)) {
|
/* finished processing ap->tpkt */
|
clear_bit(XMIT_FULL, &ap->xmit_flags);
|
done = 1;
|
}
|
continue;
|
}
|
/*
|
* We haven't made any progress this time around.
|
* Clear XMIT_BUSY to let other callers in, but
|
* after doing so we have to check if anyone set
|
* XMIT_WAKEUP since we last checked it. If they
|
* did, we should try again to set XMIT_BUSY and go
|
* around again in case XMIT_BUSY was still set when
|
* the other caller tried.
|
*/
|
clear_bit(XMIT_BUSY, &ap->xmit_flags);
|
/* any more work to do? if not, exit the loop */
|
if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) ||
|
(!tty_stuffed && ap->tpkt)))
|
break;
|
/* more work to do, see if we can do it now */
|
if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
|
break;
|
}
|
spin_unlock_bh(&ap->xmit_lock);
|
return done;
|
|
flush:
|
clear_bit(XMIT_BUSY, &ap->xmit_flags);
|
if (ap->tpkt) {
|
kfree_skb(ap->tpkt);
|
ap->tpkt = NULL;
|
clear_bit(XMIT_FULL, &ap->xmit_flags);
|
done = 1;
|
}
|
ap->optr = ap->olim;
|
spin_unlock_bh(&ap->xmit_lock);
|
return done;
|
}
|
|
/*
|
* Flush output from our internal buffers.
|
* Called for the TCFLSH ioctl. Can be entered in parallel
|
* but this is covered by the xmit_lock.
|
*/
|
static void
|
ppp_async_flush_output(struct asyncppp *ap)
|
{
|
int done = 0;
|
|
spin_lock_bh(&ap->xmit_lock);
|
ap->optr = ap->olim;
|
if (ap->tpkt != NULL) {
|
kfree_skb(ap->tpkt);
|
ap->tpkt = NULL;
|
clear_bit(XMIT_FULL, &ap->xmit_flags);
|
done = 1;
|
}
|
spin_unlock_bh(&ap->xmit_lock);
|
if (done)
|
ppp_output_wakeup(&ap->chan);
|
}
|
|
/*
|
* Receive-side routines.
|
*/
|
|
/* see how many ordinary chars there are at the start of buf */
|
static inline int
|
scan_ordinary(struct asyncppp *ap, const unsigned char *buf, int count)
|
{
|
int i, c;
|
|
for (i = 0; i < count; ++i) {
|
c = buf[i];
|
if (c == PPP_ESCAPE || c == PPP_FLAG ||
|
(c < 0x20 && (ap->raccm & (1 << c)) != 0))
|
break;
|
}
|
return i;
|
}
|
|
/* called when a flag is seen - do end-of-packet processing */
|
static void
|
process_input_packet(struct asyncppp *ap)
|
{
|
struct sk_buff *skb;
|
unsigned char *p;
|
unsigned int len, fcs;
|
|
skb = ap->rpkt;
|
if (ap->state & (SC_TOSS | SC_ESCAPE))
|
goto err;
|
|
if (skb == NULL)
|
return; /* 0-length packet */
|
|
/* check the FCS */
|
p = skb->data;
|
len = skb->len;
|
if (len < 3)
|
goto err; /* too short */
|
fcs = PPP_INITFCS;
|
for (; len > 0; --len)
|
fcs = PPP_FCS(fcs, *p++);
|
if (fcs != PPP_GOODFCS)
|
goto err; /* bad FCS */
|
skb_trim(skb, skb->len - 2);
|
|
/* check for address/control and protocol compression */
|
p = skb->data;
|
if (p[0] == PPP_ALLSTATIONS) {
|
/* chop off address/control */
|
if (p[1] != PPP_UI || skb->len < 3)
|
goto err;
|
p = skb_pull(skb, 2);
|
}
|
|
/* If protocol field is not compressed, it can be LCP packet */
|
if (!(p[0] & 0x01)) {
|
unsigned int proto;
|
|
if (skb->len < 2)
|
goto err;
|
proto = (p[0] << 8) + p[1];
|
if (proto == PPP_LCP)
|
async_lcp_peek(ap, p, skb->len, 1);
|
}
|
|
/* queue the frame to be processed */
|
skb->cb[0] = ap->state;
|
skb_queue_tail(&ap->rqueue, skb);
|
ap->rpkt = NULL;
|
ap->state = 0;
|
return;
|
|
err:
|
/* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */
|
ap->state = SC_PREV_ERROR;
|
if (skb) {
|
/* make skb appear as freshly allocated */
|
skb_trim(skb, 0);
|
skb_reserve(skb, - skb_headroom(skb));
|
}
|
}
|
|
/* Called when the tty driver has data for us. Runs parallel with the
|
other ldisc functions but will not be re-entered */
|
|
static void
|
ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
|
char *flags, int count)
|
{
|
struct sk_buff *skb;
|
int c, i, j, n, s, f;
|
unsigned char *sp;
|
|
/* update bits used for 8-bit cleanness detection */
|
if (~ap->rbits & SC_RCV_BITS) {
|
s = 0;
|
for (i = 0; i < count; ++i) {
|
c = buf[i];
|
if (flags && flags[i] != 0)
|
continue;
|
s |= (c & 0x80)? SC_RCV_B7_1: SC_RCV_B7_0;
|
c = ((c >> 4) ^ c) & 0xf;
|
s |= (0x6996 & (1 << c))? SC_RCV_ODDP: SC_RCV_EVNP;
|
}
|
ap->rbits |= s;
|
}
|
|
while (count > 0) {
|
/* scan through and see how many chars we can do in bulk */
|
if ((ap->state & SC_ESCAPE) && buf[0] == PPP_ESCAPE)
|
n = 1;
|
else
|
n = scan_ordinary(ap, buf, count);
|
|
f = 0;
|
if (flags && (ap->state & SC_TOSS) == 0) {
|
/* check the flags to see if any char had an error */
|
for (j = 0; j < n; ++j)
|
if ((f = flags[j]) != 0)
|
break;
|
}
|
if (f != 0) {
|
/* start tossing */
|
ap->state |= SC_TOSS;
|
|
} else if (n > 0 && (ap->state & SC_TOSS) == 0) {
|
/* stuff the chars in the skb */
|
skb = ap->rpkt;
|
if (!skb) {
|
skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
|
if (!skb)
|
goto nomem;
|
ap->rpkt = skb;
|
}
|
if (skb->len == 0) {
|
/* Try to get the payload 4-byte aligned.
|
* This should match the
|
* PPP_ALLSTATIONS/PPP_UI/compressed tests in
|
* process_input_packet, but we do not have
|
* enough chars here to test buf[1] and buf[2].
|
*/
|
if (buf[0] != PPP_ALLSTATIONS)
|
skb_reserve(skb, 2 + (buf[0] & 1));
|
}
|
if (n > skb_tailroom(skb)) {
|
/* packet overflowed MRU */
|
ap->state |= SC_TOSS;
|
} else {
|
sp = skb_put_data(skb, buf, n);
|
if (ap->state & SC_ESCAPE) {
|
sp[0] ^= PPP_TRANS;
|
ap->state &= ~SC_ESCAPE;
|
}
|
}
|
}
|
|
if (n >= count)
|
break;
|
|
c = buf[n];
|
if (flags != NULL && flags[n] != 0) {
|
ap->state |= SC_TOSS;
|
} else if (c == PPP_FLAG) {
|
process_input_packet(ap);
|
} else if (c == PPP_ESCAPE) {
|
ap->state |= SC_ESCAPE;
|
} else if (I_IXON(ap->tty)) {
|
if (c == START_CHAR(ap->tty))
|
start_tty(ap->tty);
|
else if (c == STOP_CHAR(ap->tty))
|
stop_tty(ap->tty);
|
}
|
/* otherwise it's a char in the recv ACCM */
|
++n;
|
|
buf += n;
|
if (flags)
|
flags += n;
|
count -= n;
|
}
|
return;
|
|
nomem:
|
printk(KERN_ERR "PPPasync: no memory (input pkt)\n");
|
ap->state |= SC_TOSS;
|
}
|
|
/*
|
* We look at LCP frames going past so that we can notice
|
* and react to the LCP configure-ack from the peer.
|
* In the situation where the peer has been sent a configure-ack
|
* already, LCP is up once it has sent its configure-ack
|
* so the immediately following packet can be sent with the
|
* configured LCP options. This allows us to process the following
|
* packet correctly without pppd needing to respond quickly.
|
*
|
* We only respond to the received configure-ack if we have just
|
* sent a configure-request, and the configure-ack contains the
|
* same data (this is checked using a 16-bit crc of the data).
|
*/
|
#define CONFREQ 1 /* LCP code field values */
|
#define CONFACK 2
|
#define LCP_MRU 1 /* LCP option numbers */
|
#define LCP_ASYNCMAP 2
|
|
static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
|
int len, int inbound)
|
{
|
int dlen, fcs, i, code;
|
u32 val;
|
|
data += 2; /* skip protocol bytes */
|
len -= 2;
|
if (len < 4) /* 4 = code, ID, length */
|
return;
|
code = data[0];
|
if (code != CONFACK && code != CONFREQ)
|
return;
|
dlen = get_unaligned_be16(data + 2);
|
if (len < dlen)
|
return; /* packet got truncated or length is bogus */
|
|
if (code == (inbound? CONFACK: CONFREQ)) {
|
/*
|
* sent confreq or received confack:
|
* calculate the crc of the data from the ID field on.
|
*/
|
fcs = PPP_INITFCS;
|
for (i = 1; i < dlen; ++i)
|
fcs = PPP_FCS(fcs, data[i]);
|
|
if (!inbound) {
|
/* outbound confreq - remember the crc for later */
|
ap->lcp_fcs = fcs;
|
return;
|
}
|
|
/* received confack, check the crc */
|
fcs ^= ap->lcp_fcs;
|
ap->lcp_fcs = -1;
|
if (fcs != 0)
|
return;
|
} else if (inbound)
|
return; /* not interested in received confreq */
|
|
/* process the options in the confack */
|
data += 4;
|
dlen -= 4;
|
/* data[0] is code, data[1] is length */
|
while (dlen >= 2 && dlen >= data[1] && data[1] >= 2) {
|
switch (data[0]) {
|
case LCP_MRU:
|
val = get_unaligned_be16(data + 2);
|
if (inbound)
|
ap->mru = val;
|
else
|
ap->chan.mtu = val;
|
break;
|
case LCP_ASYNCMAP:
|
val = get_unaligned_be32(data + 2);
|
if (inbound)
|
ap->raccm = val;
|
else
|
ap->xaccm[0] = val;
|
break;
|
}
|
dlen -= data[1];
|
data += data[1];
|
}
|
}
|
|
static void __exit ppp_async_cleanup(void)
|
{
|
if (tty_unregister_ldisc(N_PPP) != 0)
|
printk(KERN_ERR "failed to unregister PPP line discipline\n");
|
}
|
|
module_init(ppp_async_init);
|
module_exit(ppp_async_cleanup);
|
