/* * 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 991018== */ /* $Id: ppp_synctty.c,v 1.3 1999/09/02 05:30:10 paulus Exp $ */ #include #include #include #include #include #include #include #include #include #include #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 }; /* * Utility procedures to print a buffer in hex/ascii */ static void ppp_print_hex (register __u8 * out, const __u8 * in, int count) { register __u8 next_ch; static char hex[] = "0123456789ABCDEF"; while (count-- > 0) { next_ch = *in++; *out++ = hex[(next_ch >> 4) & 0x0F]; *out++ = hex[next_ch & 0x0F]; ++out; } } static void ppp_print_char (register __u8 * out, const __u8 * in, int count) { register __u8 next_ch; while (count-- > 0) { next_ch = *in++; if (next_ch < 0x20 || next_ch > 0x7e) *out++ = '.'; else { *out++ = next_ch; if (next_ch == '%') /* printk/syslogd has a bug !! */ *out++ = '%'; } } *out = '\0'; } static void ppp_print_buffer (const char *name, const __u8 *buf, int count) { __u8 line[44]; if (name != NULL) printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count); while (count > 8) { memset (line, 32, 44); ppp_print_hex (line, buf, 8); ppp_print_char (&line[8 * 3], buf, 8); printk(KERN_DEBUG "%s\n", line); count -= 8; buf += 8; } if (count > 0) { memset (line, 32, 44); ppp_print_hex (line, buf, count); ppp_print_char (&line[8 * 3], buf, count); printk(KERN_DEBUG "%s\n", line); } } /* * 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); 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; /* compress protocol field if option enabled */ if (data[0] == 0 && (ap->flags & SC_COMP_PROT) && !islcp) skb_pull(skb,1); /* 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_push(skb,2); skb->data[0] = PPP_ALLSTATIONS; skb->data[1] = PPP_UI; } ap->last_xmit = jiffies; break; } if (skb && ap->flags & SC_LOG_OUTPKT) ppp_print_buffer ("send buffer", skb->data, skb->len); 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 */ skb_queue_head(&ap->xq,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; } if (ap->flags & SC_LOG_INPKT) ppp_print_buffer ("receive buffer", buf, count); /* 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 */