patch-2.3.24 linux/drivers/net/ppp_synctty.c

• Lines: 769
• Date: Mon Oct 25 08:26:52 1999
• Orig file: v2.3.23/linux/drivers/net/ppp_synctty.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.23/linux/drivers/net/ppp_synctty.c linux/drivers/net/ppp_synctty.c
@@ -0,0 +1,768 @@
+/*
+ * PPP synchronous tty channel driver for Linux.
+ *
+ * This is a ppp channel driver that can be used with tty device drivers
+ * that are frame oriented, such as synchronous HDLC devices.
+ *
+ * Complete PPP frames without encoding/decoding are exchanged between
+ * the channel driver and the device driver.
+ * 
+ * The async map IOCTL codes are implemented to keep the user mode
+ * applications happy if they call them. Synchronous PPP does not use
+ * the async maps.
+ *
+ * Copyright 1999 Paul Mackerras.
+ *
+ * Also touched by the grubby hands of Paul Fulghum paulkf@microgate.com
+ *
+ *  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 sync 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 sync-only
+ * PPP driver, written by Michael Callahan and Al Longyear, and
+ * subsequently hacked by Paul Mackerras.
+ *
+ * ==FILEVERSION 991014==
+ */
+
+/* $Id: ppp_synctty.c,v 1.3 1999/09/02 05:30:10 paulus Exp $ */
+
+#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/ppp_defs.h>
+#include <linux/if_ppp.h>
+#include <linux/ppp_channel.h>
+#include <asm/uaccess.h>
+
+#define PPP_VERSION	"2.4.0"
+
+/* Structure for storing local state. */
+struct syncppp {
+	struct tty_struct *tty;
+	unsigned int	flags;
+	unsigned int	rbits;
+	int		mru;
+	unsigned long	busy;
+	u32		xaccm[8];
+	u32		raccm;
+	unsigned int	bytes_sent;
+	unsigned int	bytes_rcvd;
+
+	struct sk_buff	*tpkt;
+	struct sk_buff_head xq;
+	unsigned long	last_xmit;
+
+	struct sk_buff	*rpkt;
+	struct sk_buff_head rq;
+	wait_queue_head_t rwait;
+
+	struct ppp_channel chan;	/* interface to generic ppp layer */
+	int		connected;
+};
+
+/* Bit numbers in busy */
+#define XMIT_BUSY	0
+#define RECV_BUSY	1
+#define XMIT_WAKEUP	2
+#define XMIT_FULL	3
+
+/* Bits in rbits */
+#define SC_RCV_BITS	(SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
+
+#define PPPSYNC_MAX_RQLEN	32	/* arbitrary */
+
+/*
+ * Prototypes.
+ */
+static struct sk_buff* ppp_sync_txdequeue(struct syncppp *ap);
+static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb);
+static int ppp_sync_push(struct syncppp *ap);
+static void ppp_sync_flush_output(struct syncppp *ap);
+static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
+			    char *flags, int count);
+
+struct ppp_channel_ops sync_ops = {
+	ppp_sync_send
+};
+
+/*
+ * Routines for locking and unlocking the transmit and receive paths.
+ */
+static inline void
+lock_path(struct syncppp *ap, int bit)
+{
+	do {
+		while (test_bit(bit, &ap->busy))
+		       mb();
+	} while (test_and_set_bit(bit, &ap->busy));
+	mb();
+}
+
+static inline int
+trylock_path(struct syncppp *ap, int bit)
+{
+	if (test_and_set_bit(bit, &ap->busy))
+		return 0;
+	mb();
+	return 1;
+}
+
+static inline void
+unlock_path(struct syncppp *ap, int bit)
+{
+	mb();
+	clear_bit(bit, &ap->busy);
+}
+
+#define lock_xmit_path(ap)	lock_path(ap, XMIT_BUSY)
+#define trylock_xmit_path(ap)	trylock_path(ap, XMIT_BUSY)
+#define unlock_xmit_path(ap)	unlock_path(ap, XMIT_BUSY)
+#define lock_recv_path(ap)	lock_path(ap, RECV_BUSY)
+#define trylock_recv_path(ap)	trylock_path(ap, RECV_BUSY)
+#define unlock_recv_path(ap)	unlock_path(ap, RECV_BUSY)
+
+static inline void
+flush_skb_queue(struct sk_buff_head *q)
+{
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(q)) != 0)
+		kfree_skb(skb);
+}
+
+/*
+ * Routines implementing the synchronous PPP line discipline.
+ */
+
+/*
+ * Called when a tty is put into line discipline.
+ */
+static int
+ppp_sync_open(struct tty_struct *tty)
+{
+	struct syncppp *ap;
+
+	ap = kmalloc(sizeof(*ap), GFP_KERNEL);
+	if (ap == 0)
+		return -ENOMEM;
+
+	MOD_INC_USE_COUNT;
+
+	/* initialize the syncppp structure */
+	memset(ap, 0, sizeof(*ap));
+	ap->tty = tty;
+	ap->mru = PPP_MRU;
+	ap->xaccm[0] = ~0U;
+	ap->xaccm[3] = 0x60000000U;
+	ap->raccm = ~0U;
+	skb_queue_head_init(&ap->xq);
+	skb_queue_head_init(&ap->rq);
+	init_waitqueue_head(&ap->rwait);
+
+	tty->disc_data = ap;
+
+	return 0;
+}
+
+/*
+ * Called when the tty is put into another line discipline
+ * (or it hangs up).
+ */
+static void
+ppp_sync_close(struct tty_struct *tty)
+{
+	struct syncppp *ap = tty->disc_data;
+
+	if (ap == 0)
+		return;
+	tty->disc_data = 0;
+	lock_xmit_path(ap);
+	lock_recv_path(ap);
+	if (ap->rpkt != 0)
+		kfree_skb(ap->rpkt);
+	flush_skb_queue(&ap->rq);
+	if (ap->tpkt != 0)
+		kfree_skb(ap->tpkt);
+	flush_skb_queue(&ap->xq);
+	if (ap->connected)
+		ppp_unregister_channel(&ap->chan);
+	kfree(ap);
+	MOD_DEC_USE_COUNT;
+}
+
+/*
+ * Read a PPP frame.  pppd can use this to negotiate over the
+ * channel before it joins it to a bundle.
+ */
+static ssize_t
+ppp_sync_read(struct tty_struct *tty, struct file *file,
+	       unsigned char *buf, size_t count)
+{
+	struct syncppp *ap = tty->disc_data;
+	DECLARE_WAITQUEUE(wait, current);
+	ssize_t ret;
+	struct sk_buff *skb = 0;
+
+	ret = -ENXIO;
+	if (ap == 0)
+		goto out;		/* should never happen */
+
+	add_wait_queue(&ap->rwait, &wait);
+	current->state = TASK_INTERRUPTIBLE;
+	for (;;) {
+		ret = -EAGAIN;
+		skb = skb_dequeue(&ap->rq);
+		if (skb)
+			break;
+		if (file->f_flags & O_NONBLOCK)
+			break;
+		ret = -ERESTARTSYS;
+		if (signal_pending(current))
+			break;
+		schedule();
+	}
+	current->state = TASK_RUNNING;
+	remove_wait_queue(&ap->rwait, &wait);
+
+	if (skb == 0)
+		goto out;
+
+	ret = -EOVERFLOW;
+	if (skb->len > count)
+		goto outf;
+	ret = -EFAULT;
+	if (copy_to_user(buf, skb->data, skb->len))
+		goto outf;
+	ret = skb->len;
+
+ outf:
+	kfree_skb(skb);
+ out:
+	return ret;
+}
+
+/*
+ * Write a ppp frame.  pppd can use this to send frames over
+ * this particular channel.
+ */
+static ssize_t
+ppp_sync_write(struct tty_struct *tty, struct file *file,
+		const unsigned char *buf, size_t count)
+{
+	struct syncppp *ap = tty->disc_data;
+	struct sk_buff *skb;
+	ssize_t ret;
+
+	ret = -ENXIO;
+	if (ap == 0)
+		goto out;	/* should never happen */
+
+	ret = -ENOMEM;
+	skb = alloc_skb(count + 2, GFP_KERNEL);
+	if (skb == 0)
+		goto out;
+	skb_reserve(skb, 2);
+	ret = -EFAULT;
+	if (copy_from_user(skb_put(skb, count), buf, count)) {
+		kfree_skb(skb);
+		goto out;
+	}
+
+	skb_queue_tail(&ap->xq, skb);
+	ppp_sync_push(ap);
+
+	ret = count;
+
+ out:
+	return ret;
+}
+
+static int
+ppp_sync_ioctl(struct tty_struct *tty, struct file *file,
+		unsigned int cmd, unsigned long arg)
+{
+	struct syncppp *ap = tty->disc_data;
+	int err, val;
+	u32 accm[8];
+	struct sk_buff *skb;
+
+	err = -ENXIO;
+	if (ap == 0)
+		goto out;	/* should never happen */
+	err = -EPERM;
+	if (!capable(CAP_NET_ADMIN))
+		goto out;
+
+	err = -EFAULT;
+	switch (cmd) {
+	case PPPIOCGFLAGS:
+		val = ap->flags | ap->rbits;
+		if (put_user(val, (int *) arg))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSFLAGS:
+		if (get_user(val, (int *) arg))
+			break;
+		ap->flags = val & ~SC_RCV_BITS;
+		ap->rbits = val & SC_RCV_BITS;
+		err = 0;
+		break;
+
+	case PPPIOCGASYNCMAP:
+		if (put_user(ap->xaccm[0], (u32 *) arg))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSASYNCMAP:
+		if (get_user(ap->xaccm[0], (u32 *) arg))
+			break;
+		err = 0;
+		break;
+
+	case PPPIOCGRASYNCMAP:
+		if (put_user(ap->raccm, (u32 *) arg))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSRASYNCMAP:
+		if (get_user(ap->raccm, (u32 *) arg))
+			break;
+		err = 0;
+		break;
+
+	case PPPIOCGXASYNCMAP:
+		if (copy_to_user((void *) arg, ap->xaccm, sizeof(ap->xaccm)))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSXASYNCMAP:
+		if (copy_from_user(accm, (void *) arg, 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, (int *) arg))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSMRU:
+		if (get_user(val, (int *) arg))
+			break;
+		if (val < PPP_MRU)
+			val = PPP_MRU;
+		ap->mru = val;
+		err = 0;
+		break;
+
+	case PPPIOCATTACH:
+		if (get_user(val, (int *) arg))
+			break;
+		err = -EALREADY;
+		if (ap->connected)
+			break;
+		ap->chan.private = ap;
+		ap->chan.ops = &sync_ops;
+		err = ppp_register_channel(&ap->chan, val);
+		if (err != 0)
+			break;
+		ap->connected = 1;
+		break;
+	case PPPIOCDETACH:
+		err = -ENXIO;
+		if (!ap->connected)
+			break;
+		ppp_unregister_channel(&ap->chan);
+		ap->connected = 0;
+		err = 0;
+		break;
+
+	case TCGETS:
+	case TCGETA:
+		err = n_tty_ioctl(tty, file, cmd, arg);
+		break;
+
+	case TCFLSH:
+		/* flush our buffers and the serial port's buffer */
+		if (arg == TCIFLUSH || arg == TCIOFLUSH)
+			flush_skb_queue(&ap->rq);
+		if (arg == TCIOFLUSH || arg == TCOFLUSH)
+			ppp_sync_flush_output(ap);
+		err = n_tty_ioctl(tty, file, cmd, arg);
+		break;
+
+	case FIONREAD:
+		val = 0;
+		if ((skb = skb_peek(&ap->rq)) != 0)
+			val = skb->len;
+		if (put_user(val, (int *) arg))
+			break;
+		err = 0;
+		break;
+
+	default:
+		err = -ENOIOCTLCMD;
+	}
+ out:
+	return err;
+}
+
+static unsigned int
+ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
+{
+	struct syncppp *ap = tty->disc_data;
+	unsigned int mask;
+
+	if (ap == 0)
+		return 0;	/* should never happen */
+	poll_wait(file, &ap->rwait, wait);
+	mask = POLLOUT | POLLWRNORM;
+	if (skb_peek(&ap->rq))
+		mask |= POLLIN | POLLRDNORM;
+	if (test_bit(TTY_OTHER_CLOSED, &tty->flags) || tty_hung_up_p(file))
+		mask |= POLLHUP;
+	return mask;
+}
+
+static int
+ppp_sync_room(struct tty_struct *tty)
+{
+	return 65535;
+}
+
+static void
+ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
+		  char *flags, int count)
+{
+	struct syncppp *ap = tty->disc_data;
+
+	if (ap == 0)
+		return;
+	trylock_recv_path(ap);
+	ppp_sync_input(ap, buf, flags, count);
+	unlock_recv_path(ap);
+	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
+	    && tty->driver.unthrottle)
+		tty->driver.unthrottle(tty);
+}
+
+static void
+ppp_sync_wakeup(struct tty_struct *tty)
+{
+	struct syncppp *ap = tty->disc_data;
+
+	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+	if (ap == 0)
+		return;
+	if (ppp_sync_push(ap) && ap->connected)
+		ppp_output_wakeup(&ap->chan);
+}
+
+
+static struct tty_ldisc ppp_sync_ldisc = {
+	magic:	TTY_LDISC_MAGIC,
+	name:	"pppsync",
+	open:	ppp_sync_open,
+	close:	ppp_sync_close,
+	read:	ppp_sync_read,
+	write:	ppp_sync_write,
+	ioctl:	ppp_sync_ioctl,
+	poll:	ppp_sync_poll,
+	receive_room: ppp_sync_room,
+	receive_buf: ppp_sync_receive,
+	write_wakeup: ppp_sync_wakeup,
+};
+
+int
+ppp_sync_init(void)
+{
+	int err;
+
+	err = tty_register_ldisc(N_SYNC_PPP, &ppp_sync_ldisc);
+	if (err != 0)
+		printk(KERN_ERR "PPP_sync: error %d registering line disc.\n",
+		       err);
+	return err;
+}
+
+/*
+ * Procedures for encapsulation and framing.
+ */
+
+struct sk_buff*
+ppp_sync_txdequeue(struct syncppp *ap)
+{
+	int proto;
+	unsigned char *data;
+	int islcp;
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(&ap->xq)) != NULL) {
+
+		data  = skb->data;
+		proto = (data[0] << 8) + data[1];
+
+		/* LCP packets with codes between 1 (configure-request)
+		 * and 7 (code-reject) must be sent as though no options
+		 * have been negotiated.
+		 */
+		islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
+
+		/* prepend address/control fields if necessary */
+		if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
+			if (skb_headroom(skb) < 2) {
+				struct sk_buff *npkt = dev_alloc_skb(skb->len + 2);
+				if (npkt == NULL) {
+					kfree_skb(skb);
+					continue;
+				}
+				skb_reserve(npkt,2);
+				memcpy(skb_put(npkt,skb->len), skb->data, skb->len);
+				kfree_skb(skb);
+				skb = npkt;
+			}
+			skb_pull(skb,2);
+			skb->data[0] = PPP_ALLSTATIONS;
+			skb->data[1] = PPP_UI;
+		}
+
+		ap->last_xmit = jiffies;
+		break;
+	}
+
+	return skb;
+}
+
+/*
+ * Transmit-side routines.
+ */
+
+/*
+ * Send a packet to the peer over an sync 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_sync_send(struct ppp_channel *chan, struct sk_buff *skb)
+{
+	struct syncppp *ap = chan->private;
+
+	ppp_sync_push(ap);
+
+	if (test_and_set_bit(XMIT_FULL, &ap->busy))
+		return 0;	/* already full */
+	ap->tpkt = skb;
+
+	ppp_sync_push(ap);
+	return 1;
+}
+
+/*
+ * Push as much data as possible out to the tty.
+ */
+static int
+ppp_sync_push(struct syncppp *ap)
+{
+	int sent, done = 0;
+	struct tty_struct *tty = ap->tty;
+	int tty_stuffed = 0;
+
+	if (!trylock_xmit_path(ap)) {
+		set_bit(XMIT_WAKEUP, &ap->busy);
+		return 0;
+	}
+	for (;;) {
+		if (test_and_clear_bit(XMIT_WAKEUP, &ap->busy))
+			tty_stuffed = 0;
+		if (ap->tpkt == 0) {
+			if ((ap->tpkt = ppp_sync_txdequeue(ap)) == 0) {
+				clear_bit(XMIT_FULL, &ap->busy);
+			        done = 1;
+			}
+		}
+		if (!tty_stuffed && ap->tpkt != NULL) {
+			set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+			sent = tty->driver.write(tty, 0, ap->tpkt->data, ap->tpkt->len);
+			if (sent < 0)
+				goto flush;	/* error, e.g. loss of CD */
+			if (sent < ap->tpkt->len) {
+				tty_stuffed = 1;
+			} else {
+				kfree_skb(ap->tpkt);
+				ap->tpkt = 0;
+			}
+			continue;
+		}
+		/* haven't made any progress */
+		unlock_xmit_path(ap);
+		if (!(test_bit(XMIT_WAKEUP, &ap->busy)
+		      || (!tty_stuffed && ap->tpkt != 0)))
+			break;
+		if (!trylock_xmit_path(ap))
+			break;
+	}
+	return done;
+
+flush:
+	if (ap->tpkt != 0) {
+		kfree_skb(ap->tpkt);
+		ap->tpkt = 0;
+		clear_bit(XMIT_FULL, &ap->busy);
+		done = 1;
+	}
+	unlock_xmit_path(ap);
+	return done;
+}
+
+/*
+ * Flush output from our internal buffers.
+ * Called for the TCFLSH ioctl.
+ */
+static void
+ppp_sync_flush_output(struct syncppp *ap)
+{
+	int done = 0;
+
+	flush_skb_queue(&ap->xq);
+	lock_xmit_path(ap);
+	if (ap->tpkt != NULL) {
+		kfree_skb(ap->tpkt);
+		ap->tpkt = 0;
+		clear_bit(XMIT_FULL, &ap->busy);
+		done = 1;
+	}
+	unlock_xmit_path(ap);
+	if (done && ap->connected)
+		ppp_output_wakeup(&ap->chan);
+}
+
+/*
+ * Receive-side routines.
+ */
+
+static inline void
+process_input_packet(struct syncppp *ap)
+{
+	struct sk_buff *skb;
+	unsigned char *p;
+	int code = 0;
+
+	skb = ap->rpkt;
+	ap->rpkt = 0;
+
+	/* strip address/control field if present */
+	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);
+	}
+
+	/* decompress protocol field if compressed */
+	if (p[0] & 1) {
+		/* protocol is compressed */
+		skb_push(skb, 1)[0] = 0;
+	} else if (skb->len < 2)
+		goto err;
+
+	/* pass to generic layer or queue it */
+	if (ap->connected) {
+		ppp_input(&ap->chan, skb);
+	} else {
+		skb_queue_tail(&ap->rq, skb);
+		/* drop old frames if queue too long */
+		while (ap->rq.qlen > PPPSYNC_MAX_RQLEN
+		       && (skb = skb_dequeue(&ap->rq)) != 0)
+			kfree(skb);
+		wake_up_interruptible(&ap->rwait);
+	}
+	return;
+
+ err:
+	kfree_skb(skb);
+	if (ap->connected)
+		ppp_input_error(&ap->chan, code);
+}
+
+static inline void
+input_error(struct syncppp *ap, int code)
+{
+	if (ap->connected)
+		ppp_input_error(&ap->chan, code);
+}
+
+/* called when the tty driver has data for us. 
+ *
+ * Data is frame oriented: each call to ppp_sync_input is considered
+ * a whole frame. If the 1st flag byte is non-zero then the whole
+ * frame is considered to be in error and is tossed.
+ */
+static void
+ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
+		char *flags, int count)
+{
+	struct sk_buff *skb;
+	unsigned char *sp;
+
+	if (count == 0)
+		return;
+
+	/* if flag set, then error, ignore frame */
+	if (flags != 0 && *flags) {
+		input_error(ap, *flags);
+		return;
+	}
+
+	/* stuff the chars in the skb */
+	if ((skb = ap->rpkt) == 0) {
+		if ((skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2)) == 0) {
+			printk(KERN_ERR "PPPsync: no memory (input pkt)\n");
+			input_error(ap, 0);
+			return;
+		}
+		/* Try to get the payload 4-byte aligned */
+		if (buf[0] != PPP_ALLSTATIONS)
+			skb_reserve(skb, 2 + (buf[0] & 1));
+		ap->rpkt = skb;
+	}
+	if (count > skb_tailroom(skb)) {
+		/* packet overflowed MRU */
+		input_error(ap, 1);
+	} else {
+		sp = skb_put(skb, count);
+		memcpy(sp, buf, count);
+		process_input_packet(ap);
+	}
+}
+
+#ifdef MODULE
+int
+init_module(void)
+{
+	return ppp_sync_init();
+}
+
+void
+cleanup_module(void)
+{
+	if (tty_register_ldisc(N_SYNC_PPP, NULL) != 0)
+		printk(KERN_ERR "failed to unregister Sync PPP line discipline\n");
+}
+#endif /* MODULE */