1045 lines
24 KiB
C
1045 lines
24 KiB
C
/*
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* PPP async serial channel driver for Linux.
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*
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* Copyright 1999 Paul Mackerras.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* This driver provides the encapsulation and framing for sending
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* and receiving PPP frames over async serial lines. It relies on
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* the generic PPP layer to give it frames to send and to process
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* received frames. It implements the PPP line discipline.
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*
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* Part of the code in this driver was inspired by the old async-only
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* PPP driver, written by Michael Callahan and Al Longyear, and
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* subsequently hacked by Paul Mackerras.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/tty.h>
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#include <linux/netdevice.h>
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#include <linux/poll.h>
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#include <linux/crc-ccitt.h>
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#include <linux/ppp_defs.h>
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#include <linux/if_ppp.h>
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#include <linux/ppp_channel.h>
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#include <linux/spinlock.h>
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#include <linux/init.h>
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#include <asm/uaccess.h>
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#include <asm/string.h>
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#define PPP_VERSION "2.4.2"
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#define OBUFSIZE 256
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/* Structure for storing local state. */
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struct asyncppp {
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struct tty_struct *tty;
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unsigned int flags;
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unsigned int state;
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unsigned int rbits;
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int mru;
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spinlock_t xmit_lock;
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spinlock_t recv_lock;
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unsigned long xmit_flags;
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u32 xaccm[8];
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u32 raccm;
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unsigned int bytes_sent;
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unsigned int bytes_rcvd;
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struct sk_buff *tpkt;
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int tpkt_pos;
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u16 tfcs;
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unsigned char *optr;
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unsigned char *olim;
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unsigned long last_xmit;
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struct sk_buff *rpkt;
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int lcp_fcs;
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struct sk_buff_head rqueue;
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struct tasklet_struct tsk;
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atomic_t refcnt;
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struct semaphore dead_sem;
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struct ppp_channel chan; /* interface to generic ppp layer */
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unsigned char obuf[OBUFSIZE];
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};
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/* Bit numbers in xmit_flags */
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#define XMIT_WAKEUP 0
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#define XMIT_FULL 1
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#define XMIT_BUSY 2
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/* State bits */
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#define SC_TOSS 1
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#define SC_ESCAPE 2
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#define SC_PREV_ERROR 4
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/* Bits in rbits */
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#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
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static int flag_time = HZ;
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module_param(flag_time, int, 0);
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MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_LDISC(N_PPP);
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/*
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* Prototypes.
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*/
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static int ppp_async_encode(struct asyncppp *ap);
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static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb);
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static int ppp_async_push(struct asyncppp *ap);
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static void ppp_async_flush_output(struct asyncppp *ap);
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static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
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char *flags, int count);
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static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd,
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unsigned long arg);
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static void ppp_async_process(unsigned long arg);
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static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
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int len, int inbound);
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static struct ppp_channel_ops async_ops = {
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ppp_async_send,
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ppp_async_ioctl
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};
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/*
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* Routines implementing the PPP line discipline.
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*/
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/*
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* We have a potential race on dereferencing tty->disc_data,
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* because the tty layer provides no locking at all - thus one
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* cpu could be running ppp_asynctty_receive while another
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* calls ppp_asynctty_close, which zeroes tty->disc_data and
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* frees the memory that ppp_asynctty_receive is using. The best
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* way to fix this is to use a rwlock in the tty struct, but for now
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* we use a single global rwlock for all ttys in ppp line discipline.
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*
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* FIXME: this is no longer true. The _close path for the ldisc is
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* now guaranteed to be sane.
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*/
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static DEFINE_RWLOCK(disc_data_lock);
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static struct asyncppp *ap_get(struct tty_struct *tty)
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{
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struct asyncppp *ap;
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read_lock(&disc_data_lock);
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ap = tty->disc_data;
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if (ap != NULL)
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atomic_inc(&ap->refcnt);
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read_unlock(&disc_data_lock);
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return ap;
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}
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static void ap_put(struct asyncppp *ap)
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{
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if (atomic_dec_and_test(&ap->refcnt))
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up(&ap->dead_sem);
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}
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/*
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* Called when a tty is put into PPP line discipline. Called in process
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* context.
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*/
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static int
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ppp_asynctty_open(struct tty_struct *tty)
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{
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struct asyncppp *ap;
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int err;
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err = -ENOMEM;
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ap = kmalloc(sizeof(*ap), GFP_KERNEL);
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if (ap == 0)
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goto out;
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/* initialize the asyncppp structure */
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memset(ap, 0, sizeof(*ap));
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ap->tty = tty;
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ap->mru = PPP_MRU;
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spin_lock_init(&ap->xmit_lock);
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spin_lock_init(&ap->recv_lock);
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ap->xaccm[0] = ~0U;
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ap->xaccm[3] = 0x60000000U;
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ap->raccm = ~0U;
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ap->optr = ap->obuf;
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ap->olim = ap->obuf;
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ap->lcp_fcs = -1;
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skb_queue_head_init(&ap->rqueue);
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tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap);
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atomic_set(&ap->refcnt, 1);
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init_MUTEX_LOCKED(&ap->dead_sem);
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ap->chan.private = ap;
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ap->chan.ops = &async_ops;
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ap->chan.mtu = PPP_MRU;
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err = ppp_register_channel(&ap->chan);
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if (err)
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goto out_free;
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tty->disc_data = ap;
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return 0;
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out_free:
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kfree(ap);
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out:
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return err;
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}
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/*
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* Called when the tty is put into another line discipline
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* or it hangs up. We have to wait for any cpu currently
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* executing in any of the other ppp_asynctty_* routines to
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* finish before we can call ppp_unregister_channel and free
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* the asyncppp struct. This routine must be called from
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* process context, not interrupt or softirq context.
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*/
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static void
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ppp_asynctty_close(struct tty_struct *tty)
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{
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struct asyncppp *ap;
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write_lock_irq(&disc_data_lock);
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ap = tty->disc_data;
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tty->disc_data = NULL;
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write_unlock_irq(&disc_data_lock);
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if (ap == 0)
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return;
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/*
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* We have now ensured that nobody can start using ap from now
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* on, but we have to wait for all existing users to finish.
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* Note that ppp_unregister_channel ensures that no calls to
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* our channel ops (i.e. ppp_async_send/ioctl) are in progress
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* by the time it returns.
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*/
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if (!atomic_dec_and_test(&ap->refcnt))
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down(&ap->dead_sem);
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tasklet_kill(&ap->tsk);
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ppp_unregister_channel(&ap->chan);
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if (ap->rpkt != 0)
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kfree_skb(ap->rpkt);
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skb_queue_purge(&ap->rqueue);
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if (ap->tpkt != 0)
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kfree_skb(ap->tpkt);
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kfree(ap);
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}
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/*
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* Called on tty hangup in process context.
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*
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* Wait for I/O to driver to complete and unregister PPP channel.
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* This is already done by the close routine, so just call that.
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*/
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static int ppp_asynctty_hangup(struct tty_struct *tty)
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{
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ppp_asynctty_close(tty);
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return 0;
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}
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/*
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* Read does nothing - no data is ever available this way.
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* Pppd reads and writes packets via /dev/ppp instead.
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*/
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static ssize_t
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ppp_asynctty_read(struct tty_struct *tty, struct file *file,
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unsigned char __user *buf, size_t count)
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{
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return -EAGAIN;
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}
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/*
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* Write on the tty does nothing, the packets all come in
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* from the ppp generic stuff.
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*/
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static ssize_t
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ppp_asynctty_write(struct tty_struct *tty, struct file *file,
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const unsigned char *buf, size_t count)
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{
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return -EAGAIN;
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}
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/*
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* Called in process context only. May be re-entered by multiple
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* ioctl calling threads.
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*/
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static int
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ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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struct asyncppp *ap = ap_get(tty);
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int err, val;
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int __user *p = (int __user *)arg;
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if (ap == 0)
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return -ENXIO;
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err = -EFAULT;
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switch (cmd) {
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case PPPIOCGCHAN:
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err = -ENXIO;
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if (ap == 0)
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break;
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err = -EFAULT;
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if (put_user(ppp_channel_index(&ap->chan), p))
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break;
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err = 0;
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break;
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case PPPIOCGUNIT:
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err = -ENXIO;
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if (ap == 0)
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break;
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err = -EFAULT;
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if (put_user(ppp_unit_number(&ap->chan), p))
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break;
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err = 0;
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break;
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case TCGETS:
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case TCGETA:
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err = n_tty_ioctl(tty, file, cmd, arg);
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break;
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case TCFLSH:
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/* flush our buffers and the serial port's buffer */
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if (arg == TCIOFLUSH || arg == TCOFLUSH)
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ppp_async_flush_output(ap);
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err = n_tty_ioctl(tty, file, cmd, arg);
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break;
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case FIONREAD:
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val = 0;
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if (put_user(val, p))
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break;
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err = 0;
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break;
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default:
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err = -ENOIOCTLCMD;
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}
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ap_put(ap);
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return err;
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}
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/* No kernel lock - fine */
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static unsigned int
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ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
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{
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return 0;
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}
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static int
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ppp_asynctty_room(struct tty_struct *tty)
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{
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return 65535;
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}
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/*
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* This can now be called from hard interrupt level as well
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* as soft interrupt level or mainline.
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*/
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static void
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ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
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char *cflags, int count)
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{
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struct asyncppp *ap = ap_get(tty);
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unsigned long flags;
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if (ap == 0)
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return;
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spin_lock_irqsave(&ap->recv_lock, flags);
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ppp_async_input(ap, buf, cflags, count);
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spin_unlock_irqrestore(&ap->recv_lock, flags);
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if (!skb_queue_empty(&ap->rqueue))
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tasklet_schedule(&ap->tsk);
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ap_put(ap);
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if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
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&& tty->driver->unthrottle)
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tty->driver->unthrottle(tty);
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}
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static void
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ppp_asynctty_wakeup(struct tty_struct *tty)
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{
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struct asyncppp *ap = ap_get(tty);
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clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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if (ap == 0)
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return;
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set_bit(XMIT_WAKEUP, &ap->xmit_flags);
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tasklet_schedule(&ap->tsk);
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ap_put(ap);
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}
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static struct tty_ldisc ppp_ldisc = {
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.owner = THIS_MODULE,
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.magic = TTY_LDISC_MAGIC,
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.name = "ppp",
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.open = ppp_asynctty_open,
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.close = ppp_asynctty_close,
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.hangup = ppp_asynctty_hangup,
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.read = ppp_asynctty_read,
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.write = ppp_asynctty_write,
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.ioctl = ppp_asynctty_ioctl,
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.poll = ppp_asynctty_poll,
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.receive_room = ppp_asynctty_room,
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.receive_buf = ppp_asynctty_receive,
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.write_wakeup = ppp_asynctty_wakeup,
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};
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static int __init
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ppp_async_init(void)
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{
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int err;
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err = tty_register_ldisc(N_PPP, &ppp_ldisc);
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if (err != 0)
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printk(KERN_ERR "PPP_async: error %d registering line disc.\n",
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err);
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return err;
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}
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/*
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* The following routines provide the PPP channel interface.
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*/
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static int
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ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
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{
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struct asyncppp *ap = chan->private;
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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int err, val;
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u32 accm[8];
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err = -EFAULT;
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switch (cmd) {
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case PPPIOCGFLAGS:
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val = ap->flags | ap->rbits;
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if (put_user(val, p))
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break;
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err = 0;
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break;
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case PPPIOCSFLAGS:
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if (get_user(val, p))
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break;
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ap->flags = val & ~SC_RCV_BITS;
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spin_lock_irq(&ap->recv_lock);
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ap->rbits = val & SC_RCV_BITS;
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spin_unlock_irq(&ap->recv_lock);
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err = 0;
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break;
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case PPPIOCGASYNCMAP:
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if (put_user(ap->xaccm[0], (u32 __user *)argp))
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break;
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err = 0;
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break;
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case PPPIOCSASYNCMAP:
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if (get_user(ap->xaccm[0], (u32 __user *)argp))
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break;
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err = 0;
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break;
|
|
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case PPPIOCGRASYNCMAP:
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if (put_user(ap->raccm, (u32 __user *)argp))
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break;
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err = 0;
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break;
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case PPPIOCSRASYNCMAP:
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if (get_user(ap->raccm, (u32 __user *)argp))
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break;
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err = 0;
|
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break;
|
|
|
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case PPPIOCGXASYNCMAP:
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if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
|
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break;
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err = 0;
|
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break;
|
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case PPPIOCSXASYNCMAP:
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if (copy_from_user(accm, argp, sizeof(accm)))
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break;
|
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accm[2] &= ~0x40000000U; /* can't escape 0x5e */
|
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accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */
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memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
|
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err = 0;
|
|
break;
|
|
|
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case PPPIOCGMRU:
|
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if (put_user(ap->mru, p))
|
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break;
|
|
err = 0;
|
|
break;
|
|
case PPPIOCSMRU:
|
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if (get_user(val, p))
|
|
break;
|
|
if (val < PPP_MRU)
|
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val = PPP_MRU;
|
|
ap->mru = val;
|
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err = 0;
|
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break;
|
|
|
|
default:
|
|
err = -ENOTTY;
|
|
}
|
|
|
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return err;
|
|
}
|
|
|
|
/*
|
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* This is called at softirq level to deliver received packets
|
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* to the ppp_generic code, and to tell the ppp_generic code
|
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* if we can accept more output now.
|
|
*/
|
|
static void ppp_async_process(unsigned long arg)
|
|
{
|
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struct asyncppp *ap = (struct asyncppp *) arg;
|
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struct sk_buff *skb;
|
|
|
|
/* process received packets */
|
|
while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
|
|
if (skb->cb[0])
|
|
ppp_input_error(&ap->chan, 0);
|
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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 ^ 0x20; \
|
|
} 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 = (data[0] << 8) + data[1];
|
|
|
|
/*
|
|
* 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
|
|
|| 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->driver->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 != 0) {
|
|
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 != 0)))
|
|
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 != 0) {
|
|
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 && p[1] == PPP_UI) {
|
|
/* chop off address/control */
|
|
if (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 != 0 && 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 != 0 && (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 == 0) {
|
|
skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
|
|
if (skb == 0)
|
|
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] ^= 0x20;
|
|
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 != 0)
|
|
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 = (data[2] << 8) + data[3];
|
|
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 = (data[2] << 8) + data[3];
|
|
if (inbound)
|
|
ap->mru = val;
|
|
else
|
|
ap->chan.mtu = val;
|
|
break;
|
|
case LCP_ASYNCMAP:
|
|
val = (data[2] << 24) + (data[3] << 16)
|
|
+ (data[4] << 8) + data[5];
|
|
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);
|