hdlc_fr.c

linux-2.6.15.6

/*
 * Generic HDLC support routines for Linux
 * Frame Relay support
 *
 * Copyright (C) 1999 - 2005 Krzysztof Halasa <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 *

            Theory of PVC state

 DCE mode:

 (exist,new) -> 0,0 when "PVC create" or if "link unreliable"
         0,x -> 1,1 if "link reliable" when sending FULL STATUS
         1,1 -> 1,0 if received FULL STATUS ACK

 (active)    -> 0 when "ifconfig PVC down" or "link unreliable" or "PVC create"
             -> 1 when "PVC up" and (exist,new) = 1,0

 DTE mode:
 (exist,new,active) = FULL STATUS if "link reliable"
		    = 0, 0, 0 if "link unreliable"
 No LMI:
 active = open and "link reliable"
 exist = new = not used

 CCITT LMI: ITU-T Q.933 Annex A
 ANSI LMI: ANSI T1.617 Annex D
 CISCO LMI: the original, aka "Gang of Four" LMI

*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/errno.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/pkt_sched.h>
#include <linux/random.h>
#include <linux/inetdevice.h>
#include <linux/lapb.h>
#include <linux/rtnetlink.h>
#include <linux/etherdevice.h>
#include <linux/hdlc.h>

#undef DEBUG_PKT
#undef DEBUG_ECN
#undef DEBUG_LINK

#define FR_UI			0x03
#define FR_PAD			0x00

#define NLPID_IP		0xCC
#define NLPID_IPV6		0x8E
#define NLPID_SNAP		0x80
#define NLPID_PAD		0x00
#define NLPID_CCITT_ANSI_LMI	0x08
#define NLPID_CISCO_LMI		0x09


#define LMI_CCITT_ANSI_DLCI	   0 /* LMI DLCI */
#define LMI_CISCO_DLCI		1023

#define LMI_CALLREF		0x00 /* Call Reference */
#define LMI_ANSI_LOCKSHIFT	0x95 /* ANSI locking shift */
#define LMI_ANSI_CISCO_REPTYPE	0x01 /* report type */
#define LMI_CCITT_REPTYPE	0x51
#define LMI_ANSI_CISCO_ALIVE	0x03 /* keep alive */
#define LMI_CCITT_ALIVE		0x53
#define LMI_ANSI_CISCO_PVCSTAT	0x07 /* PVC status */
#define LMI_CCITT_PVCSTAT	0x57

#define LMI_FULLREP		0x00 /* full report  */
#define LMI_INTEGRITY		0x01 /* link integrity report */
#define LMI_SINGLE		0x02 /* single PVC report */

#define LMI_STATUS_ENQUIRY      0x75
#define LMI_STATUS              0x7D /* reply */

#define LMI_REPT_LEN               1 /* report type element length */
#define LMI_INTEG_LEN              2 /* link integrity element length */

#define LMI_CCITT_CISCO_LENGTH	  13 /* LMI frame lengths */
#define LMI_ANSI_LENGTH		  14


typedef struct {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	unsigned ea1:	1;
	unsigned cr:	1;
	unsigned dlcih:	6;
  
	unsigned ea2:	1;
	unsigned de:	1;
	unsigned becn:	1;
	unsigned fecn:	1;
	unsigned dlcil:	4;
#else
	unsigned dlcih:	6;
	unsigned cr:	1;
	unsigned ea1:	1;

	unsigned dlcil:	4;
	unsigned fecn:	1;
	unsigned becn:	1;
	unsigned de:	1;
	unsigned ea2:	1;
#endif
}__attribute__ ((packed)) fr_hdr;


static inline u16 q922_to_dlci(u8 *hdr)
{
	return ((hdr[0] & 0xFC) << 2) | ((hdr[1] & 0xF0) >> 4);
}



static inline void dlci_to_q922(u8 *hdr, u16 dlci)
{
	hdr[0] = (dlci >> 2) & 0xFC;
	hdr[1] = ((dlci << 4) & 0xF0) | 0x01;
}



static inline pvc_device* find_pvc(hdlc_device *hdlc, u16 dlci)
{
	pvc_device *pvc = hdlc->state.fr.first_pvc;

	while (pvc) {
		if (pvc->dlci == dlci)
			return pvc;
		if (pvc->dlci > dlci)
			return NULL; /* the listed is sorted */
		pvc = pvc->next;
	}

	return NULL;
}


static inline pvc_device* add_pvc(struct net_device *dev, u16 dlci)
{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	pvc_device *pvc, **pvc_p = &hdlc->state.fr.first_pvc;

	while (*pvc_p) {
		if ((*pvc_p)->dlci == dlci)
			return *pvc_p;
		if ((*pvc_p)->dlci > dlci)
			break;	/* the list is sorted */
		pvc_p = &(*pvc_p)->next;
	}

	pvc = kmalloc(sizeof(pvc_device), GFP_ATOMIC);
	if (!pvc)
		return NULL;

	memset(pvc, 0, sizeof(pvc_device));
	pvc->dlci = dlci;
	pvc->master = dev;
	pvc->next = *pvc_p;	/* Put it in the chain */
	*pvc_p = pvc;
	return pvc;
}


static inline int pvc_is_used(pvc_device *pvc)
{
	return pvc->main != NULL || pvc->ether != NULL;
}


static inline void pvc_carrier(int on, pvc_device *pvc)
{
	if (on) {
		if (pvc->main)
			if (!netif_carrier_ok(pvc->main))
				netif_carrier_on(pvc->main);
		if (pvc->ether)
			if (!netif_carrier_ok(pvc->ether))
				netif_carrier_on(pvc->ether);
	} else {
		if (pvc->main)
			if (netif_carrier_ok(pvc->main))
				netif_carrier_off(pvc->main);
		if (pvc->ether)
			if (netif_carrier_ok(pvc->ether))
				netif_carrier_off(pvc->ether);
	}
}


static inline void delete_unused_pvcs(hdlc_device *hdlc)
{
	pvc_device **pvc_p = &hdlc->state.fr.first_pvc;

	while (*pvc_p) {
		if (!pvc_is_used(*pvc_p)) {
			pvc_device *pvc = *pvc_p;
			*pvc_p = pvc->next;
			kfree(pvc);
			continue;
		}
		pvc_p = &(*pvc_p)->next;
	}
}


static inline struct net_device** get_dev_p(pvc_device *pvc, int type)
{
	if (type == ARPHRD_ETHER)
		return &pvc->ether;
	else
		return &pvc->main;
}


static int fr_hard_header(struct sk_buff **skb_p, u16 dlci)
{
	u16 head_len;
	struct sk_buff *skb = *skb_p;

	switch (skb->protocol) {
	case __constant_ntohs(NLPID_CCITT_ANSI_LMI):
		head_len = 4;
		skb_push(skb, head_len);
		skb->data[3] = NLPID_CCITT_ANSI_LMI;
		break;

	case __constant_ntohs(NLPID_CISCO_LMI):
		head_len = 4;
		skb_push(skb, head_len);
		skb->data[3] = NLPID_CISCO_LMI;
		break;

	case __constant_ntohs(ETH_P_IP):
		head_len = 4;
		skb_push(skb, head_len);
		skb->data[3] = NLPID_IP;
		break;

	case __constant_ntohs(ETH_P_IPV6):
		head_len = 4;
		skb_push(skb, head_len);
		skb->data[3] = NLPID_IPV6;
		break;

	case __constant_ntohs(ETH_P_802_3):
		head_len = 10;
		if (skb_headroom(skb) < head_len) {
			struct sk_buff *skb2 = skb_realloc_headroom(skb,
								    head_len);
			if (!skb2)
				return -ENOBUFS;
			dev_kfree_skb(skb);
			skb = *skb_p = skb2;
		}
		skb_push(skb, head_len);
		skb->data[3] = FR_PAD;
		skb->data[4] = NLPID_SNAP;
		skb->data[5] = FR_PAD;
		skb->data[6] = 0x80;
		skb->data[7] = 0xC2;
		skb->data[8] = 0x00;
		skb->data[9] = 0x07; /* bridged Ethernet frame w/out FCS */
		break;

	default:
		head_len = 10;
		skb_push(skb, head_len);
		skb->data[3] = FR_PAD;
		skb->data[4] = NLPID_SNAP;
		skb->data[5] = FR_PAD;
		skb->data[6] = FR_PAD;
		skb->data[7] = FR_PAD;
		*(u16*)(skb->data + 8) = skb->protocol;
	}

	dlci_to_q922(skb->data, dlci);
	skb->data[2] = FR_UI;
	return 0;
}



static int pvc_open(struct net_device *dev)
{
	pvc_device *pvc = dev_to_pvc(dev);

	if ((pvc->master->flags & IFF_UP) == 0)
		return -EIO;  /* Master must be UP in order to activate PVC */

	if (pvc->open_count++ == 0) {
		hdlc_device *hdlc = dev_to_hdlc(pvc->master);
		if (hdlc->state.fr.settings.lmi == LMI_NONE)
			pvc->state.active = hdlc->carrier;

		pvc_carrier(pvc->state.active, pvc);
		hdlc->state.fr.dce_changed = 1;
	}
	return 0;
}



static int pvc_close(struct net_device *dev)
{
	pvc_device *pvc = dev_to_pvc(dev);

	if (--pvc->open_count == 0) {
		hdlc_device *hdlc = dev_to_hdlc(pvc->master);
		if (hdlc->state.fr.settings.lmi == LMI_NONE)
			pvc->state.active = 0;

		if (hdlc->state.fr.settings.dce) {
			hdlc->state.fr.dce_changed = 1;
			pvc->state.active = 0;
		}
	}
	return 0;
}



static int pvc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
	pvc_device *pvc = dev_to_pvc(dev);
	fr_proto_pvc_info info;

	if (ifr->ifr_settings.type == IF_GET_PROTO) {
		if (dev->type == ARPHRD_ETHER)
			ifr->ifr_settings.type = IF_PROTO_FR_ETH_PVC;
		else
			ifr->ifr_settings.type = IF_PROTO_FR_PVC;

		if (ifr->ifr_settings.size < sizeof(info)) {
			/* data size wanted */
			ifr->ifr_settings.size = sizeof(info);
			return -ENOBUFS;
		}

		info.dlci = pvc->dlci;
		memcpy(info.master, pvc->master->name, IFNAMSIZ);
		if (copy_to_user(ifr->ifr_settings.ifs_ifsu.fr_pvc_info,
				 &info, sizeof(info)))
			return -EFAULT;
		return 0;
	}

	return -EINVAL;
}


static inline struct net_device_stats *pvc_get_stats(struct net_device *dev)
{
	return netdev_priv(dev);
}



static int pvc_xmit(struct sk_buff *skb, struct net_device *dev)
{
	pvc_device *pvc = dev_to_pvc(dev);
	struct net_device_stats *stats = pvc_get_stats(dev);

	if (pvc->state.active) {
		if (dev->type == ARPHRD_ETHER) {
			int pad = ETH_ZLEN - skb->len;
			if (pad > 0) { /* Pad the frame with zeros */
				int len = skb->len;
				if (skb_tailroom(skb) < pad)
					if (pskb_expand_head(skb, 0, pad,
							     GFP_ATOMIC)) {
						stats->tx_dropped++;
						dev_kfree_skb(skb);
						return 0;
					}
				skb_put(skb, pad);
				memset(skb->data + len, 0, pad);
			}
			skb->protocol = __constant_htons(ETH_P_802_3);
		}
		if (!fr_hard_header(&skb, pvc->dlci)) {
			stats->tx_bytes += skb->len;
			stats->tx_packets++;
			if (pvc->state.fecn) /* TX Congestion counter */
				stats->tx_compressed++;
			skb->dev = pvc->master;
			dev_queue_xmit(skb);
			return 0;
		}
	}

	stats->tx_dropped++;
	dev_kfree_skb(skb);
	return 0;
}



static int pvc_change_mtu(struct net_device *dev, int new_mtu)
{
	if ((new_mtu < 68) || (new_mtu > HDLC_MAX_MTU))
		return -EINVAL;
	dev->mtu = new_mtu;
	return 0;
}



static inline void fr_log_dlci_active(pvc_device *pvc)
{
	printk(KERN_INFO "%s: DLCI %d [%s%s%s]%s %s\n",
	       pvc->master->name,
	       pvc->dlci,
	       pvc->main ? pvc->main->name : "",
	       pvc->main && pvc->ether ? " " : "",
	       pvc->ether ? pvc->ether->name : "",
	       pvc->state.new ? " new" : "",
	       !pvc->state.exist ? "deleted" :
	       pvc->state.active ? "active" : "inactive");
}



static inline u8 fr_lmi_nextseq(u8 x)
{
	x++;
	return x ? x : 1;
}



static void fr_lmi_send(struct net_device *dev, int fullrep)
{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	struct sk_buff *skb;
	pvc_device *pvc = hdlc->state.fr.first_pvc;
	int lmi = hdlc->state.fr.settings.lmi;
	int dce = hdlc->state.fr.settings.dce;
	int len = lmi == LMI_ANSI ? LMI_ANSI_LENGTH : LMI_CCITT_CISCO_LENGTH;
	int stat_len = (lmi == LMI_CISCO) ? 6 : 3;
	u8 *data;
	int i = 0;

	if (dce && fullrep) {
		len += hdlc->state.fr.dce_pvc_count * (2 + stat_len);
		if (len > HDLC_MAX_MRU) {
			printk(KERN_WARNING "%s: Too many PVCs while sending "
			       "LMI full report\n", dev->name);
			return;
		}
	}

	skb = dev_alloc_skb(len);
	if (!skb) {
		printk(KERN_WARNING "%s: Memory squeeze on fr_lmi_send()\n",
		       dev->name);
		return;
	}
	memset(skb->data, 0, len);
	skb_reserve(skb, 4);
	if (lmi == LMI_CISCO) {
		skb->protocol = __constant_htons(NLPID_CISCO_LMI);
		fr_hard_header(&skb, LMI_CISCO_DLCI);
	} else {
		skb->protocol = __constant_htons(NLPID_CCITT_ANSI_LMI);
		fr_hard_header(&skb, LMI_CCITT_ANSI_DLCI);
	}
	data = skb->tail;
	data[i++] = LMI_CALLREF;
	data[i++] = dce ? LMI_STATUS : LMI_STATUS_ENQUIRY;
	if (lmi == LMI_ANSI)
		data[i++] = LMI_ANSI_LOCKSHIFT;
	data[i++] = lmi == LMI_CCITT ? LMI_CCITT_REPTYPE :
		LMI_ANSI_CISCO_REPTYPE;
	data[i++] = LMI_REPT_LEN;
	data[i++] = fullrep ? LMI_FULLREP : LMI_INTEGRITY;
	data[i++] = lmi == LMI_CCITT ? LMI_CCITT_ALIVE : LMI_ANSI_CISCO_ALIVE;
	data[i++] = LMI_INTEG_LEN;
	data[i++] = hdlc->state.fr.txseq =fr_lmi_nextseq(hdlc->state.fr.txseq);
	data[i++] = hdlc->state.fr.rxseq;

	if (dce && fullrep) {
		while (pvc) {
			data[i++] = lmi == LMI_CCITT ? LMI_CCITT_PVCSTAT :
				LMI_ANSI_CISCO_PVCSTAT;
			data[i++] = stat_len;

			/* LMI start/restart */
			if (hdlc->state.fr.reliable && !pvc->state.exist) {
				pvc->state.exist = pvc->state.new = 1;
				fr_log_dlci_active(pvc);
			}

			/* ifconfig PVC up */
			if (pvc->open_count && !pvc->state.active &&
			    pvc->state.exist && !pvc->state.new) {
				pvc_carrier(1, pvc);
				pvc->state.active = 1;
				fr_log_dlci_active(pvc);
			}

			if (lmi == LMI_CISCO) {
				data[i] = pvc->dlci >> 8;
				data[i + 1] = pvc->dlci & 0xFF;
			} else {
				data[i] = (pvc->dlci >> 4) & 0x3F;
				data[i + 1] = ((pvc->dlci << 3) & 0x78) | 0x80;
				data[i + 2] = 0x80;
			}

			if (pvc->state.new)
				data[i + 2] |= 0x08;
			else if (pvc->state.active)
				data[i + 2] |= 0x02;

			i += stat_len;
			pvc = pvc->next;
		}
	}

	skb_put(skb, i);
	skb->priority = TC_PRIO_CONTROL;
	skb->dev = dev;
	skb->nh.raw = skb->data;

	dev_queue_xmit(skb);
}



static void fr_set_link_state(int reliable, struct net_device *dev)
{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	pvc_device *pvc = hdlc->state.fr.first_pvc;

	hdlc->state.fr.reliable = reliable;
	if (reliable) {
#if 0
		if (!netif_carrier_ok(dev))
			netif_carrier_on(dev);
#endif

		hdlc->state.fr.n391cnt = 0; /* Request full status */
		hdlc->state.fr.dce_changed = 1;

		if (hdlc->state.fr.settings.lmi == LMI_NONE) {
			while (pvc) {	/* Activate all PVCs */
				pvc_carrier(1, pvc);
				pvc->state.exist = pvc->state.active = 1;
				pvc->state.new = 0;
				pvc = pvc->next;
			}
		}
	} else {
#if 0
		if (netif_carrier_ok(dev))
			netif_carrier_off(dev);
#endif

		while (pvc) {		/* Deactivate all PVCs */
			pvc_carrier(0, pvc);
			pvc->state.exist = pvc->state.active = 0;
			pvc->state.new = 0;
			if (!hdlc->state.fr.settings.dce)
				pvc->state.bandwidth = 0;
			pvc = pvc->next;
		}
	}
}



static void fr_timer(unsigned long arg)
{
	struct net_device *dev = (struct net_device *)arg;
	hdlc_device *hdlc = dev_to_hdlc(dev);
	int i, cnt = 0, reliable;
	u32 list;

	if (hdlc->state.fr.settings.dce) {
		reliable = hdlc->state.fr.request &&
			time_before(jiffies, hdlc->state.fr.last_poll +
				    hdlc->state.fr.settings.t392 * HZ);
		hdlc->state.fr.request = 0;
	} else {
		hdlc->state.fr.last_errors <<= 1; /* Shift the list */
		if (hdlc->state.fr.request) {
			if (hdlc->state.fr.reliable)
				printk(KERN_INFO "%s: No LMI status reply "
				       "received\n", dev->name);
			hdlc->state.fr.last_errors |= 1;
		}

		list = hdlc->state.fr.last_errors;
		for (i = 0; i < hdlc->state.fr.settings.n393; i++, list >>= 1)
			cnt += (list & 1);	/* errors count */

		reliable = (cnt < hdlc->state.fr.settings.n392);
	}

	if (hdlc->state.fr.reliable != reliable) {
		printk(KERN_INFO "%s: Link %sreliable\n", dev->name,
		       reliable ? "" : "un");
		fr_set_link_state(reliable, dev);
	}

	if (hdlc->state.fr.settings.dce)
		hdlc->state.fr.timer.expires = jiffies +
			hdlc->state.fr.settings.t392 * HZ;
	else {
		if (hdlc->state.fr.n391cnt)
			hdlc->state.fr.n391cnt--;

		fr_lmi_send(dev, hdlc->state.fr.n391cnt == 0);

		hdlc->state.fr.last_poll = jiffies;
		hdlc->state.fr.request = 1;
		hdlc->state.fr.timer.expires = jiffies +
			hdlc->state.fr.settings.t391 * HZ;
	}

	hdlc->state.fr.timer.function = fr_timer;
	hdlc->state.fr.timer.data = arg;
	add_timer(&hdlc->state.fr.timer);
}