ppp.c

unix and linux net driver

 * If this procedure returns 0, ppp_output_wakeup will be called
 * exactly once.
 */
static int
ppp_async_send(struct ppp *ppp, struct sk_buff *skb)
{
	CHECK_PPP(0);

	ppp_tty_push(ppp);

	if (ppp->tpkt != NULL)
		return -1;
	ppp->tpkt = skb;
	ppp->tpkt_pos = 0;

	return ppp_tty_push(ppp);
}

/*
 * Push as much data as possible out to the tty.
 * Returns 1 if we finished encoding the current frame, 0 otherwise.
 */
static int
ppp_tty_push(struct ppp *ppp)
{
	int avail, sent, done = 0;
	struct tty_struct *tty = ppp2tty(ppp);
	
	if (ppp->flags & SC_SYNC) 
		return ppp_tty_sync_push(ppp);

	CHECK_PPP(0);
	if (ppp->tty_pushing) {
		ppp->woke_up = 1;
		return 0;
	}
	if (tty == NULL || tty->disc_data != (void *) ppp)
		goto flush;
	while (ppp->optr < ppp->olim || ppp->tpkt != 0) {
		ppp->tty_pushing = 1;
		mb();
		ppp->woke_up = 0;
		avail = ppp->olim - ppp->optr;
		if (avail > 0) {
			tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
			sent = tty->driver.write(tty, 0, ppp->optr, avail);
			if (sent < 0)
				goto flush;	/* error, e.g. loss of CD */
			ppp->stats.ppp_obytes += sent;
			ppp->optr += sent;
			if (sent < avail) {
				wmb();
				ppp->tty_pushing = 0;
				mb();
				if (ppp->woke_up)
					continue;
				return done;
			}
		}
		if (ppp->tpkt != 0)
			done = ppp_async_encode(ppp);
		wmb();
		ppp->tty_pushing = 0;
	}
	return done;

flush:
	ppp->tty_pushing = 1;
	mb();
	ppp->stats.ppp_oerrors++;
	if (ppp->tpkt != 0) {
		KFREE_SKB(ppp->tpkt);
		ppp->tpkt = 0;
		done = 1;
	}
	ppp->optr = ppp->olim;
	wmb();
	ppp->tty_pushing = 0;
	return done;
}

/*
 * Procedure to encode the data for async serial transmission.
 * Does octet stuffing (escaping) and address/control
 * and protocol compression.
 * Assumes ppp->opkt != 0 on entry.
 * Returns 1 if we finished the current frame, 0 otherwise.
 */
static int
ppp_async_encode(struct ppp *ppp)
{
	int fcs, i, count, c;
	unsigned char *buf, *buflim;
	unsigned char *data;
	int islcp;

	CHECK_PPP(0);

	buf = ppp->obuf;
	ppp->olim = buf;
	ppp->optr = buf;
	i = ppp->tpkt_pos;
	data = ppp->tpkt->data;
	count = ppp->tpkt->len;
	fcs = ppp->tfcs;

	/*
	 * LCP packets with code values between 1 (configure-reqest)
	 * and 7 (code-reject) must be sent as though no options
	 * had been negotiated.
	 */
	islcp = PPP_PROTOCOL(data) == PPP_LCP
		&& 1 <= data[PPP_HDRLEN] && data[PPP_HDRLEN] <= 7;

	if (i == 0) {
		/*
		 * Start of a new packet - insert the leading FLAG
		 * character if necessary.
		 */
		if (islcp || flag_time == 0
		    || jiffies - ppp->last_xmit >= flag_time)
			*buf++ = PPP_FLAG;
		/* only reset idle time for data packets */
		if (PPP_PROTOCOL(data) < 0x8000)
			ppp->last_xmit = jiffies;
		fcs = PPP_INITFCS;
		++ppp->stats.ppp_opackets;
		ppp->stats.ppp_ooctects += count;

		/*
		 * Do address/control compression
		 */
		if ((ppp->flags & SC_COMP_AC) != 0 && !islcp
		    && PPP_ADDRESS(data) == PPP_ALLSTATIONS
		    && PPP_CONTROL(data) == PPP_UI)
			i += 2;
	}

	/*
	 * 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 = buf + OBUFSIZE - 6;
	while (i < count && buf < buflim) {
		c = data[i++];
		if (i == 3 && c == 0 && (ppp->flags & SC_COMP_PROT))
			continue;	/* compress protocol field */
		fcs = PPP_FCS(fcs, c);
		if (in_xmap(ppp, c) || (islcp && c < 0x20)) {
			*buf++ = PPP_ESCAPE;
			c ^= 0x20;
		}
		*buf++ = c;
	}

	if (i == count) {
		/*
		 * We have finished the packet.  Add the FCS and flag.
		 */
		fcs = ~fcs;
		c = fcs & 0xff;
		if (in_xmap(ppp, c) || (islcp && c < 0x20)) {
			*buf++ = PPP_ESCAPE;
			c ^= 0x20;
		}
		*buf++ = c;
		c = (fcs >> 8) & 0xff;
		if (in_xmap(ppp, c) || (islcp && c < 0x20)) {
			*buf++ = PPP_ESCAPE;
			c ^= 0x20;
		}
		*buf++ = c;
		*buf++ = PPP_FLAG;
		ppp->olim = buf;

		KFREE_SKB(ppp->tpkt);
		ppp->tpkt = 0;
		return 1;
	}

	/*
	 * Remember where we are up to in this packet.
	 */
	ppp->olim = buf;
	ppp->tpkt_pos = i;
	ppp->tfcs = fcs;
	return 0;
}

/*
 * Flush output from our internal buffers.
 * Called for the TCFLSH ioctl.
 */
static void
ppp_tty_flush_output(struct ppp *ppp)
{
	struct sk_buff *skb;
	int done = 0;

	while ((skb = skb_dequeue(&ppp->xmt_q)) != NULL)
		KFREE_SKB(skb);
	ppp->tty_pushing = 1;
	mb();
	ppp->optr = ppp->olim;
	if (ppp->tpkt != NULL) {
		KFREE_SKB(ppp->tpkt);
		ppp->tpkt = 0;
		done = 1;
	}
	wmb();
	ppp->tty_pushing = 0;
	if (done)
		ppp_output_wakeup(ppp);
}

/*
 * Callback function from tty driver. Return the amount of space left
 * in the receiver's buffer to decide if remote transmitter is to be
 * throttled.
 */
static int
ppp_tty_room (struct tty_struct *tty)
{
	return 65536;	    /* We can handle an infinite amount of data. :-) */
}

/*
 * Callback function when data is available at the tty driver.
 */
static void
ppp_tty_receive (struct tty_struct *tty, const __u8 * data,
		 char *flags, int count)
{
	register struct ppp *ppp = tty2ppp (tty);
	struct sk_buff *skb;
	int chr, flg;
	unsigned char *p;

	if (ppp != 0)
		CHECK_PPP_VOID();
	/*
	 * This can happen if stuff comes in on the backup tty.
	 */
	if (ppp == 0 || tty != ppp->tty)
		return;
	/*
	 * Verify the table pointer and ensure that the line is
	 * still in PPP discipline.
	 */
	if (ppp->magic != PPP_MAGIC) {
		if (ppp->flags & SC_DEBUG)
			printk(KERN_DEBUG
			       "PPP: tty_receive called but couldn't find "
			       "PPP struct.\n");
		return;
	}
	/*
	 * Print the buffer if desired
	 */
	if (ppp->flags & SC_LOG_RAWIN)
		ppp_print_buffer ("receive buffer", data, count);

	ppp->stats.ppp_ibytes += count;
	skb = ppp->rpkt;
	
	if ( ppp->flags & SC_SYNC ) {
		/* synchronous mode */
		
		if (ppp->toss==0xE0) {
			/* this is the 1st frame, reset vj comp */
			ppp_receive_error(ppp);
			ppp->toss = 0;
		}
		
		/*
		 * Allocate an skbuff for frame.
		 * The 128 is room for VJ header expansion.
		 */
		
		if (skb == NULL)
			skb = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
			
		if (skb == NULL) {
			if (ppp->flags & SC_DEBUG)
				printk(KERN_DEBUG "couldn't "
				       "alloc skb for recv\n");
		} else {
			LIBERATE_SKB(skb);
			/*
			 * Decompress A/C and protocol compression here.
			 */
			p = skb_put(skb, 2);
			p[0] = PPP_ALLSTATIONS;
			p[1] = PPP_UI;
			if (*data == PPP_ALLSTATIONS) {
				data += 2;
				count -= 2;
			}
			if ((*data & 1) != 0) {
				p = skb_put(skb, 1);
				p[0] = 0;
			}

			/* copy frame to socket buffer */
			p = skb_put(skb, count);
			memcpy(p,data,count);
			
			/*
			 * Check if we've overflowed the MRU
			 */
			if (skb->len >= ppp->mru + PPP_HDRLEN + 2
			    || skb_tailroom(skb) <= 0) {
				++ppp->estats.rx_length_errors;
				if (ppp->flags & SC_DEBUG)
					printk(KERN_DEBUG "rcv frame too long: "
					       "len=%d mru=%d hroom=%d troom=%d\n",
					       skb->len, ppp->mru, skb_headroom(skb),
					       skb_tailroom(skb));
			} else {
				if (!ppp_receive_frame(ppp, skb)) {
					KFREE_SKB(skb);
					ppp_receive_error(ppp);
				}
			}
		
			/* Reset for the next frame */
			skb = NULL;
		}
		ppp->rpkt = skb;
		return;
	}
	
	while (count-- > 0) {
		/*
		 * Collect the character and error condition for the character.
		 * Set the toss flag for the first character error.
		 */
		chr = *data++;
		if (flags) {
			flg = *flags++;
			if (flg) {
				if (ppp->toss == 0)
					ppp->toss = flg;
				switch (flg) {
				case TTY_OVERRUN:
					++ppp->estats.rx_fifo_errors;
					break;
				case TTY_FRAME:
				case TTY_BREAK:
					++ppp->estats.rx_frame_errors;
					break;
				}
				continue;
			}
		}

		/*
		 * Set the flags for d7 being 0/1 and parity being
		 * even/odd so that the normal processing would have
		 * all flags set at the end of the session.  A
		 * missing flag bit indicates an error condition.
		 */

#ifdef CHECK_CHARACTERS
		if (chr & 0x80)
			ppp->flags |= SC_RCV_B7_1;
		else
			ppp->flags |= SC_RCV_B7_0;

		if (paritytab[chr >> 5] & (1 << (chr & 0x1F)))
			ppp->flags |= SC_RCV_ODDP;
		else
			ppp->flags |= SC_RCV_EVNP;
#endif

		if (chr == PPP_FLAG) {
			/*
			 * FLAG. This is the end of the block. If the block
			 * ends with ESC FLAG, then the block is to be ignored.
			 */
			if (ppp->escape)
				ppp->toss |= 0x80;
			/*
			 * Process the frame if it was received correctly.
			 * If there was an error, let the VJ decompressor know.
			 * There are 4 cases here:
			 * skb != NULL, toss != 0: error in frame
			 * skb != NULL, toss == 0: frame ok
			 * skb == NULL, toss != 0: very first frame,
			 *	error on 1st char, or alloc_skb failed
			 * skb == NULL, toss == 0: empty frame (~~)
			 */
			if (ppp->toss || !ppp_receive_frame(ppp, skb)) {
				if (ppp->toss && (ppp->flags & SC_DEBUG))
					printk(KERN_DEBUG
					       "ppp: tossing frame (%x)\n",
					       ppp->toss);
				if (skb != NULL)
					KFREE_SKB(skb);
				if (!(ppp->toss == 0xE0 || ppp->toss == 0x80))
					++ppp->stats.ppp_ierrors;
				ppp_receive_error(ppp);
			}
			/*
			 * Reset for the next frame.
			 */
			skb = NULL;
			ppp->rfcs = PPP_INITFCS;
			ppp->escape = 0;
			ppp->toss = 0;
			continue;
		}

		/* If we're tossing, look no further. */
		if (ppp->toss != 0)
			continue;

		/* If this is a control char to be ignored, do so */
		if (in_rmap(ppp, chr))
			continue;

		/*
		 * Modify the next character if preceded by escape.
		 * The escape character (0x7d) could be an escaped
		 * 0x5d, if it follows an escape :-)
		 */
		if (ppp->escape) {
			chr ^= PPP_TRANS;
			ppp->escape = 0;
		} else if (chr == PPP_ESCAPE) {
			ppp->escape = PPP_TRANS;
			continue;
		}

		/*
		 * Allocate an skbuff on the first character received.
		 * The 128 is room for VJ header expansion and FCS.
		 */
		if (skb == NULL) {
			skb = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
			if (skb == NULL) {
				if (ppp->flags & SC_DEBUG)
					printk(KERN_DEBUG "couldn't "
					       "alloc skb for recv\n");
				ppp->toss = 1;
				continue;
			}
			LIBERATE_SKB(skb);
		}

		/*
		 * Decompress A/C and protocol compression here.
		 */
		if (skb->len == 0 && chr != PPP_ALLSTATIONS) {
			p = skb_put(skb, 2);
			p[0] = PPP_ALLSTATIONS;
			p[1] = PPP_UI;
		}
		if (skb->len == 2 && (chr & 1) != 0) {
			p = skb_put(skb, 1);
			p[0] = 0;
		}

		/*
		 * Check if we've overflowed the MRU
		 */
		if (skb->len >= ppp->mru + PPP_HDRLEN + 2
		    || skb_tailroom(skb) <= 0) {
			++ppp->estats.rx_length_errors;
			ppp->toss = 0xC0;
			if (ppp->flags & SC_DEBUG)
				printk(KERN_DEBUG "rcv frame too long: "
				       "len=%d mru=%d hroom=%d troom=%d\n",
				       skb->len, ppp->mru, skb_headroom(skb),
				       skb_tailroom(skb));
			continue;
		}

		/*
		 * Store the character and update the FCS.
		 */
		p = skb_put(skb, 1);
		*p = chr;
		ppp->rfcs = PPP_FCS(ppp->rfcs, chr);
	}
	ppp->rpkt = skb;
}

/*************************************************************
 * PPP NETWORK INTERFACE SUPPORT
 *	The following code implements the PPP network
 *	interface device and handles those parts of
 *	the PPP processing which are independent of the
 *	type of hardware link being used, including
 *	VJ and packet compression.
 *************************************************************/

/*
 * Network device driver callback routines
 */

static int ppp_init_dev(struct device *dev);
static int ppp_dev_open(struct device *);
static int ppp_dev_ioctl(struct device *dev, struct ifreq *ifr, int cmd);
static int ppp_dev_close(struct device *);
static int ppp_dev_xmit(struct sk_buff *, struct device *);
static struct net_device_stats *ppp_dev_stats (struct device *);

#if LINUX_VERSION_CODE < VERSION(2,1,15)
static int ppp_dev_header(struct sk_buff *, struct device *, __u16,
			  void *, void *, unsigned int);
static int ppp_dev_rebuild(void *eth, struct device *dev,
			   unsigned long raddr, struct sk_buff *skb);
#endif

/*
 * Information for the protocol decoder
 */

typedef int (*pfn_proto)  (struct ppp *, struct sk_buff *);

typedef struct ppp_proto_struct {
	int		proto;
	pfn_proto	func;
} ppp_proto_type;

static int rcv_proto_ip		(struct ppp *, struct sk_buff *);
static int rcv_proto_ipv6	(struct ppp *, struct sk_buff *);
static int rcv_proto_ipx	(struct ppp *, struct sk_buff *);
static int rcv_proto_at		(struct ppp *, struct sk_buff *);
static int rcv_proto_vjc_comp	(struct ppp *, struct sk_buff *);
static int rcv_proto_vjc_uncomp (struct ppp *, struct sk_buff *);
static int rcv_proto_ccp	(struct ppp *, struct sk_buff *);
static int rcv_proto_unknown	(struct ppp *, struct sk_buff *);

static
ppp_proto_type proto_list[] = {
	{ PPP_IP,	  rcv_proto_ip	       },
	{ PPP_IPV6,	  rcv_proto_ipv6       },
	{ PPP_IPX,	  rcv_proto_ipx	       },
	{ PPP_AT,	  rcv_proto_at	       },
	{ PPP_VJC_COMP,	  rcv_proto_vjc_comp   },
	{ PPP_VJC_UNCOMP, rcv_proto_vjc_uncomp },
	{ PPP_CCP,	  rcv_proto_ccp	       },
	{ 0,		  rcv_proto_unknown    }  /* !!! MUST BE LAST !!! */
};

/*
 * Called when the PPP network interface device is actually created.
 */
static int
ppp_init_dev (struct device *dev)
{
	dev->hard_header_len  = PPP_HDRLEN;
#if LINUX_VERSION_CODE < VERSION(2,1,15)
	dev->hard_header      = ppp_dev_header;