diff options
Diffstat (limited to 'drivers/net/ppp/ppp_async.c')
| -rw-r--r-- | drivers/net/ppp/ppp_async.c | 1028 |
1 files changed, 1028 insertions, 0 deletions
diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c new file mode 100644 index 00000000000..c6ba6438082 --- /dev/null +++ b/drivers/net/ppp/ppp_async.c @@ -0,0 +1,1028 @@ +/* + * 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/if_ppp.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 <asm/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; + + atomic_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) + atomic_inc(&ap->refcnt); + read_unlock(&disc_data_lock); + return ap; +} + +static void ap_put(struct asyncppp *ap) +{ + if (atomic_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); + + atomic_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 (!atomic_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 = tty_perform_flush(tty, 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 unsigned int +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; + + kfree_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, proto; + + 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); + } + proto = p[0]; + if (proto & 1) { + /* protocol is compressed */ + skb_push(skb, 1)[0] = 0; + } else { + if (skb->len < 2) + goto err; + proto = (proto << 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(skb, n); + memcpy(sp, 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); |