#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/capability.h>
#include <linux/seq_file.h>

/* We are an ethernet device */
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <net/sock.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/uaccess.h>
#include <asm/byteorder.h>
#include <net/checksum.h>   /* for ip_fast_csum() */
#include <net/arp.h>
#include <net/dst.h>
#include <linux/proc_fs.h>

/* And atm device */
#include <linux/atmdev.h>
#include <linux/atmlec.h>
#include <linux/atmmpc.h>
/* Modular too */
#include <linux/module.h>

#include "lec.h"
#include "mpc.h"
#include "resources.h"

/*
 * mpc.c: Implementation of MPOA client kernel part
 */

#if 0
#define dprintk(format, args...) \
	printk(KERN_DEBUG "mpoa:%s: " format, __func__, ##args)
#define dprintk_cont(format, args...) printk(KERN_CONT format, ##args)
#else
#define dprintk(format, args...)					\
	do { if (0)							\
		printk(KERN_DEBUG "mpoa:%s: " format, __func__, ##args);\
	} while (0)
#define dprintk_cont(format, args...)			\
	do { if (0) printk(KERN_CONT format, ##args); } while (0)
#endif

#if 0
#define ddprintk(format, args...) \
	printk(KERN_DEBUG "mpoa:%s: " format, __func__, ##args)
#define ddprintk_cont(format, args...) printk(KERN_CONT format, ##args)
#else
#define ddprintk(format, args...)					\
	do { if (0)							\
		printk(KERN_DEBUG "mpoa:%s: " format, __func__, ##args);\
	} while (0)
#define ddprintk_cont(format, args...)			\
	do { if (0) printk(KERN_CONT format, ##args); } while (0)
#endif

#define MPOA_TAG_LEN 4

/* mpc_daemon -> kernel */
static void MPOA_trigger_rcvd(struct k_message *msg, struct mpoa_client *mpc);
static void MPOA_res_reply_rcvd(struct k_message *msg, struct mpoa_client *mpc);
static void ingress_purge_rcvd(struct k_message *msg, struct mpoa_client *mpc);
static void egress_purge_rcvd(struct k_message *msg, struct mpoa_client *mpc);
static void mps_death(struct k_message *msg, struct mpoa_client *mpc);
static void clean_up(struct k_message *msg, struct mpoa_client *mpc,
		     int action);
static void MPOA_cache_impos_rcvd(struct k_message *msg,
				  struct mpoa_client *mpc);
static void set_mpc_ctrl_addr_rcvd(struct k_message *mesg,
				   struct mpoa_client *mpc);
static void set_mps_mac_addr_rcvd(struct k_message *mesg,
				  struct mpoa_client *mpc);

static const uint8_t *copy_macs(struct mpoa_client *mpc,
				const uint8_t *router_mac,
				const uint8_t *tlvs, uint8_t mps_macs,
				uint8_t device_type);
static void purge_egress_shortcut(struct atm_vcc *vcc, eg_cache_entry *entry);

static void send_set_mps_ctrl_addr(const char *addr, struct mpoa_client *mpc);
static void mpoad_close(struct atm_vcc *vcc);
static int msg_from_mpoad(struct atm_vcc *vcc, struct sk_buff *skb);

static void mpc_push(struct atm_vcc *vcc, struct sk_buff *skb);
static netdev_tx_t mpc_send_packet(struct sk_buff *skb,
				   struct net_device *dev);
static int mpoa_event_listener(struct notifier_block *mpoa_notifier,
			       unsigned long event, void *dev);
static void mpc_timer_refresh(void);
static void mpc_cache_check(unsigned long checking_time);

static struct llc_snap_hdr llc_snap_mpoa_ctrl = {
	0xaa, 0xaa, 0x03,
	{0x00, 0x00, 0x5e},
	{0x00, 0x03}         /* For MPOA control PDUs */
};
static struct llc_snap_hdr llc_snap_mpoa_data = {
	0xaa, 0xaa, 0x03,
	{0x00, 0x00, 0x00},
	{0x08, 0x00}         /* This is for IP PDUs only */
};
static struct llc_snap_hdr llc_snap_mpoa_data_tagged = {
	0xaa, 0xaa, 0x03,
	{0x00, 0x00, 0x00},
	{0x88, 0x4c}         /* This is for tagged data PDUs */
};

static struct notifier_block mpoa_notifier = {
	mpoa_event_listener,
	NULL,
	0
};

struct mpoa_client *mpcs = NULL; /* FIXME */
static struct atm_mpoa_qos *qos_head = NULL;
static DEFINE_TIMER(mpc_timer, NULL, 0, 0);


static struct mpoa_client *find_mpc_by_itfnum(int itf)
{
	struct mpoa_client *mpc;

	mpc = mpcs;  /* our global linked list */
	while (mpc != NULL) {
		if (mpc->dev_num == itf)
			return mpc;
		mpc = mpc->next;
	}

	return NULL;   /* not found */
}

static struct mpoa_client *find_mpc_by_vcc(struct atm_vcc *vcc)
{
	struct mpoa_client *mpc;

	mpc = mpcs;  /* our global linked list */
	while (mpc != NULL) {
		if (mpc->mpoad_vcc == vcc)
			return mpc;
		mpc = mpc->next;
	}

	return NULL;   /* not found */
}

static struct mpoa_client *find_mpc_by_lec(struct net_device *dev)
{
	struct mpoa_client *mpc;

	mpc = mpcs;  /* our global linked list */
	while (mpc != NULL) {
		if (mpc->dev == dev)
			return mpc;
		mpc = mpc->next;
	}

	return NULL;   /* not found */
}

/*
 * Functions for managing QoS list
 */

/*
 * Overwrites the old entry or makes a new one.
 */
struct atm_mpoa_qos *atm_mpoa_add_qos(__be32 dst_ip, struct atm_qos *qos)
{
	struct atm_mpoa_qos *entry;

	entry = atm_mpoa_search_qos(dst_ip);
	if (entry != NULL) {
		entry->qos = *qos;
		return entry;
	}

	entry = kmalloc(sizeof(struct atm_mpoa_qos), GFP_KERNEL);
	if (entry == NULL) {
		pr_info("mpoa: out of memory\n");
		return entry;
	}

	entry->ipaddr = dst_ip;
	entry->qos = *qos;

	entry->next = qos_head;
	qos_head = entry;

	return entry;
}

struct atm_mpoa_qos *atm_mpoa_search_qos(__be32 dst_ip)
{
	struct atm_mpoa_qos *qos;

	qos = qos_head;
	while (qos) {
		if (qos->ipaddr == dst_ip)
			break;
		qos = qos->next;
	}

	return qos;
}

/*
 * Returns 0 for failure
 */
int atm_mpoa_delete_qos(struct atm_mpoa_qos *entry)
{
	struct atm_mpoa_qos *curr;

	if (entry == NULL)
		return 0;
	if (entry == qos_head) {
		qos_head = qos_head->next;
		kfree(entry);
		return 1;
	}

	curr = qos_head;
	while (curr != NULL) {
		if (curr->next == entry) {
			curr->next = entry->next;
			kfree(entry);
			return 1;
		}
		curr = curr->next;
	}

	return 0;
}

/* this is buggered - we need locking for qos_head */
void atm_mpoa_disp_qos(struct seq_file *m)
{
	struct atm_mpoa_qos *qos;

	qos = qos_head;
	seq_printf(m, "QoS entries for shortcuts:\n");
	seq_printf(m, "IP address\n  TX:max_pcr pcr     min_pcr max_cdv max_sdu\n  RX:max_pcr pcr     min_pcr max_cdv max_sdu\n");

	while (qos != NULL) {
		seq_printf(m, "%pI4\n     %-7d %-7d %-7d %-7d %-7d\n     %-7d %-7d %-7d %-7d %-7d\n",
			   &qos->ipaddr,
			   qos->qos.txtp.max_pcr,
			   qos->qos.txtp.pcr,
			   qos->qos.txtp.min_pcr,
			   qos->qos.txtp.max_cdv,
			   qos->qos.txtp.max_sdu,
			   qos->qos.rxtp.max_pcr,
			   qos->qos.rxtp.pcr,
			   qos->qos.rxtp.min_pcr,
			   qos->qos.rxtp.max_cdv,
			   qos->qos.rxtp.max_sdu);
		qos = qos->next;
	}
}

static struct net_device *find_lec_by_itfnum(int itf)
{
	struct net_device *dev;
	char name[IFNAMSIZ];

	sprintf(name, "lec%d", itf);
	dev = dev_get_by_name(&init_net, name);

	return dev;
}

static struct mpoa_client *alloc_mpc(void)
{
	struct mpoa_client *mpc;

	mpc = kzalloc(sizeof(struct mpoa_client), GFP_KERNEL);
	if (mpc == NULL)
		return NULL;
	rwlock_init(&mpc->ingress_lock);
	rwlock_init(&mpc->egress_lock);
	mpc->next = mpcs;
	atm_mpoa_init_cache(mpc);

	mpc->parameters.mpc_p1 = MPC_P1;
	mpc->parameters.mpc_p2 = MPC_P2;
	memset(mpc->parameters.mpc_p3, 0, sizeof(mpc->parameters.mpc_p3));
	mpc->parameters.mpc_p4 = MPC_P4;
	mpc->parameters.mpc_p5 = MPC_P5;
	mpc->parameters.mpc_p6 = MPC_P6;

	mpcs = mpc;

	return mpc;
}

/*
 *
 * start_mpc() puts the MPC on line. All the packets destined
 * to the lec underneath us are now being monitored and
 * shortcuts will be established.
 *
 */
static void start_mpc(struct mpoa_client *mpc, struct net_device *dev)
{

	dprintk("(%s)\n", mpc->dev->name);
	if (!dev->netdev_ops)
		pr_info("(%s) not starting\n", dev->name);
	else {
		mpc->old_ops = dev->netdev_ops;
		mpc->new_ops = *mpc->old_ops;
		mpc->new_ops.ndo_start_xmit = mpc_send_packet;
		dev->netdev_ops = &mpc->new_ops;
	}
}

static void stop_mpc(struct mpoa_client *mpc)
{
	struct net_device *dev = mpc->dev;
	dprintk("(%s)", mpc->dev->name);

	/* Lets not nullify lec device's dev->hard_start_xmit */
	if (dev->netdev_ops != &mpc->new_ops) {
		dprintk_cont(" mpc already stopped, not fatal\n");
		return;
	}
	dprintk_cont("\n");

	dev->netdev_ops = mpc->old_ops;
	mpc->old_ops = NULL;

	/* close_shortcuts(mpc);    ??? FIXME */
}

static const char *mpoa_device_type_string(char type) __attribute__ ((unused));

static const char *mpoa_device_type_string(char type)
{
	switch (type) {
	case NON_MPOA:
		return "non-MPOA device";
	case MPS:
		return "MPS";
	case MPC:
		return "MPC";
	case MPS_AND_MPC:
		return "both MPS and MPC";
	}

	return "unspecified (non-MPOA) device";
}

/*
 * lec device calls this via its netdev_priv(dev)->lane2_ops
 * ->associate_indicator() when it sees a TLV in LE_ARP packet.
 * We fill in the pointer above when we see a LANE2 lec initializing
 * See LANE2 spec 3.1.5
 *
 * Quite a big and ugly function but when you look at it
 * all it does is to try to locate and parse MPOA Device
 * Type TLV.
 * We give our lec a pointer to this function and when the
 * lec sees a TLV it uses the pointer to call this function.
 *
 */
static void lane2_assoc_ind(struct net_device *dev, const u8 *mac_addr,
			    const u8 *tlvs, u32 sizeoftlvs)
{
	uint32_t type;
	uint8_t length, mpoa_device_type, number_of_mps_macs;
	const uint8_t *end_of_tlvs;
	struct mpoa_client *mpc;

	mpoa_device_type = number_of_mps_macs = 0; /* silence gcc */
	dprintk("(%s) received TLV(s), ", dev->name);
	dprintk("total length of all TLVs %d\n", sizeoftlvs);
	mpc = find_mpc_by_lec(dev); /* Sampo-Fix: moved here from below */
	if (mpc == NULL) {
		pr_info("(%s) no mpc\n", dev->name);
		return;
	}
	end_of_tlvs = tlvs + sizeoftlvs;
	while (end_of_tlvs - tlvs >= 5) {
		type = ((tlvs[0] << 24) | (tlvs[1] << 16) |
			(tlvs[2] << 8) | tlvs[3]);
		length = tlvs[4];
		tlvs += 5;
		dprintk("    type 0x%x length %02x\n", type, length);
		if (tlvs + length > end_of_tlvs) {
			pr_info("TLV value extends past its buffer, aborting parse\n");
			return;
		}

		if (type == 0) {
			pr_info("mpoa: (%s) TLV type was 0, returning\n",
				dev->name);
			return;
		}

		if (type != TLV_MPOA_DEVICE_TYPE) {
			tlvs += length;
			continue;  /* skip other TLVs */
		}
		mpoa_device_type = *tlvs++;
		number_of_mps_macs = *tlvs++;
		dprintk("(%s) MPOA device type '%s', ",
			dev->name, mpoa_device_type_string(mpoa_device_type));
		if (mpoa_device_type == MPS_AND_MPC &&
		    length < (42 + number_of_mps_macs*ETH_ALEN)) { /* :) */
			pr_info("(%s) short MPOA Device Type TLV\n",
				dev->name);
			continue;
		}
		if ((mpoa_device_type == MPS || mpoa_device_type == MPC) &&
		    length < 22 + number_of_mps_macs*ETH_ALEN) {
			pr_info("(%s) short MPOA Device Type TLV\n", dev->name);
			continue;
		}
		if (mpoa_device_type != MPS &&
		    mpoa_device_type != MPS_AND_MPC) {
			dprintk("ignoring non-MPS device ");
			if (mpoa_device_type == MPC)
				tlvs += 20;
			continue;  /* we are only interested in MPSs */
		}
		if (number_of_mps_macs == 0 &&
		    mpoa_device_type == MPS_AND_MPC) {
			pr_info("(%s) MPS_AND_MPC has zero MACs\n", dev->name);
			continue;  /* someone should read the spec */
		}
		dprintk_cont("this MPS has %d MAC addresses\n",
			     number_of_mps_macs);

		/*
		 * ok, now we can go and tell our daemon
		 * the control address of MPS
		 */
		send_set_mps_ctrl_addr(tlvs, mpc);

		tlvs = copy_macs(mpc, mac_addr, tlvs,
				 number_of_mps_macs, mpoa_device_type);
		if (tlvs == NULL)
			return;
	}
	if (end_of_tlvs - tlvs != 0)
		pr_info("(%s) ignoring %Zd bytes of trailing TLV garbage\n",
			dev->name, end_of_tlvs - tlvs);
}

/*
 * Store at least advertizing router's MAC address
 * plus the possible MAC address(es) to mpc->mps_macs.
 * For a freshly allocated MPOA client mpc->mps_macs == 0.
 */
static const uint8_t *copy_macs(struct mpoa_client *mpc,
				const uint8_t *router_mac,
				const uint8_t *tlvs, uint8_t mps_macs,
				uint8_t device_type)
{
	int num_macs;
	num_macs = (mps_macs > 1) ? mps_macs : 1;

	if (mpc->number_of_mps_macs != num_macs) { /* need to reallocate? */
		if (mpc->number_of_mps_macs != 0)
			kfree(mpc->mps_macs);
		mpc->number_of_mps_macs = 0;
		mpc->mps_macs = kmalloc(num_macs * ETH_ALEN, GFP_KERNEL);
		if (mpc->mps_macs == NULL) {
			pr_info("(%s) out of mem\n", mpc->dev->name);
			return NULL;
		}
	}
	memcpy(mpc->mps_macs, router_mac, ETH_ALEN);
	tlvs += 20; if (device_type == MPS_AND_MPC) tlvs += 20;
	if (mps_macs > 0)
		memcpy(mpc->mps_macs, tlvs, mps_macs*ETH_ALEN);
	tlvs += mps_macs*ETH_ALEN;
	mpc->number_of_mps_macs = num_macs;

	return tlvs;
}

static int send_via_shortcut(struct sk_buff *skb, struct mpoa_client *mpc)
{
	in_cache_entry *entry;
	struct iphdr *iph;
	char *buff;
	__be32 ipaddr = 0;

	static struct {
		struct llc_snap_hdr hdr;
		__be32 tag;
	} tagged_llc_snap_hdr = {
		{0xaa, 0xaa, 0x03, {0x00, 0x00, 0x00}, {0x88, 0x4c}},
		0
	};

	buff = skb->data + mpc->dev->hard_header_len;
	iph = (struct iphdr *)buff;
	ipaddr = iph->daddr;

	ddprintk("(%s) ipaddr 0x%x\n",
		 mpc->dev->name, ipaddr);

	entry = mpc->in_ops->get(ipaddr, mpc);
	if (entry == NULL) {
		entry = mpc->in_ops->add_entry(ipaddr, mpc);
		if (entry != NULL)
			mpc->in_ops->put(entry);
		return 1;
	}
	/* threshold not exceeded or VCC not ready */
	if (mpc->in_ops->cache_hit(entry, mpc) != OPEN) {
		ddprintk("(%s) cache_hit: returns != OPEN\n",
			 mpc->dev->name);
		mpc->in_ops->put(entry);
		return 1;
	}

	ddprintk("(%s) using shortcut\n",
		 mpc->dev->name);
	/* MPOA spec A.1.4, MPOA client must decrement IP ttl at least by one */
	if (iph->ttl <= 1) {
		ddprintk("(%s) IP ttl = %u, using LANE\n",
			 mpc->dev->name, iph->ttl);
		mpc->in_ops->put(entry);
		return 1;
	}
	iph->ttl--;
	iph->check = 0;
	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);

	if (entry->ctrl_info.tag != 0) {
		ddprintk("(%s) adding tag 0x%x\n",
			 mpc->dev->name, entry->ctrl_info.tag);
		tagged_llc_snap_hdr.tag = entry->ctrl_info.tag;
		skb_pull(skb, ETH_HLEN);	/* get rid of Eth header */
		skb_push(skb, sizeof(tagged_llc_snap_hdr));
						/* add LLC/SNAP header   */
		skb_copy_to_linear_data(skb, &tagged_llc_snap_hdr,
					sizeof(tagged_llc_snap_hdr));
	} else {
		skb_pull(skb, ETH_HLEN);	/* get rid of Eth header */
		skb_push(skb, sizeof(struct llc_snap_hdr));
						/* add LLC/SNAP header + tag  */
		skb_copy_to_linear_data(skb, &llc_snap_mpoa_data,
					sizeof(struct llc_snap_hdr));
	}

	atomic_add(skb->truesize, &sk_atm(entry->shortcut)->sk_wmem_alloc);
	ATM_SKB(skb)->atm_options = entry->shortcut->atm_options;
	entry->shortcut->send(entry->shortcut, skb);
	entry->packets_fwded++;
	mpc->in_ops->put(entry);

	return 0;
}

/*
 * Probably needs some error checks and locking, not sure...
 */
static netdev_tx_t mpc_send_packet(struct sk_buff *skb,
					 struct net_device *dev)
{
	struct mpoa_client *mpc;
	struct ethhdr *eth;
	int i = 0;

	mpc = find_mpc_by_lec(dev); /* this should NEVER fail */
	if (mpc == NULL) {
		pr_info("(%s) no MPC found\n", dev->name);
		goto non_ip;
	}

	eth = (struct ethhdr *)skb->data;
	if (eth->h_proto != htons(ETH_P_IP))
		goto non_ip; /* Multi-Protocol Over ATM :-) */

	/* Weed out funny packets (e.g., AF_PACKET or raw). */
	if (skb->len < ETH_HLEN + sizeof(struct iphdr))
		goto non_ip;
	skb_set_network_header(skb, ETH_HLEN);
	if (skb->len < ETH_HLEN + ip_hdr(skb)->ihl * 4 || ip_hdr(skb)->ihl < 5)
		goto non_ip;

	while (i < mpc->number_of_mps_macs) {
		if (!compare_ether_addr(eth->h_dest,
					(mpc->mps_macs + i*ETH_ALEN)))
			if (send_via_shortcut(skb, mpc) == 0) /* try shortcut */
				return NETDEV_TX_OK;
		i++;
	}

non_ip:
	return mpc->old_ops->ndo_start_xmit(skb, dev);
}

static int atm_mpoa_vcc_attach(struct atm_vcc *vcc, void __user *arg)
{
	int bytes_left;
	struct mpoa_client *mpc;
	struct atmmpc_ioc ioc_data;
	in_cache_entry *in_entry;
	__be32  ipaddr;

	bytes_left = copy_from_user(&ioc_data, arg, sizeof(struct atmmpc_ioc));
	if (bytes_left != 0) {
		pr_info("mpoa:Short read (missed %d bytes) from userland\n",
			bytes_left);
		return -EFAULT;
	}
	ipaddr = ioc_data.ipaddr;
	if (ioc_data.dev_num < 0 || ioc_data.dev_num >= MAX_LEC_ITF)
		return -EINVAL;

	mpc = find_mpc_by_itfnum(ioc_data.dev_num);
	if (mpc == NULL)
		return -EINVAL;

	if (ioc_data.type == MPC_SOCKET_INGRESS) {
		in_entry = mpc->in_ops->get(ipaddr, mpc);
		if (in_entry == NULL ||
		    in_entry->entry_state < INGRESS_RESOLVED) {
			pr_info("(%s) did not find RESOLVED entry from ingress cache\n",
				mpc->dev->name);
			if (in_entry != NULL)
				mpc->in_ops->put(in_entry);
			return -EINVAL;
		}
		pr_info("(%s) attaching ingress SVC, entry = %pI4\n",
			mpc->dev->name, &in_entry->ctrl_info.in_dst_ip);
		in_entry->shortcut = vcc;
		mpc->in_ops->put(in_entry);
	} else {
		pr_info("(%s) attaching egress SVC\n", mpc->dev->name);
	}

	vcc->proto_data = mpc->dev;
	vcc->push = mpc_push;

	return 0;
}

/*