/*
   * net/sched/cls_flow.c		Generic flow classifier
   *
   * Copyright (c) 2007, 2008 Patrick McHardy <kaber@trash.net>
   *
   * 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.
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/list.h>
  #include <linux/jhash.h>
  #include <linux/random.h>
  #include <linux/pkt_cls.h>
  #include <linux/skbuff.h>
  #include <linux/in.h>
  #include <linux/ip.h>
  #include <linux/ipv6.h>

  #include <linux/if_vlan.h>

  #include <linux/slab.h>

  
  #include <net/pkt_cls.h>
  #include <net/ip.h>
  #include <net/route.h>
  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  #include <net/netfilter/nf_conntrack.h>
  #endif
  
  struct flow_head {
  	struct list_head	filters;
  };
  
  struct flow_filter {
  	struct list_head	list;
  	struct tcf_exts		exts;
  	struct tcf_ematch_tree	ematches;

  	struct timer_list	perturb_timer;
  	u32			perturb_period;

  	u32			handle;
  
  	u32			nkeys;
  	u32			keymask;
  	u32			mode;
  	u32			mask;
  	u32			xor;
  	u32			rshift;
  	u32			addend;
  	u32			divisor;
  	u32			baseclass;

  	u32			hashrnd;

  };

  static const struct tcf_ext_map flow_ext_map = {
  	.action	= TCA_FLOW_ACT,
  	.police	= TCA_FLOW_POLICE,
  };
  
  static inline u32 addr_fold(void *addr)
  {
  	unsigned long a = (unsigned long)addr;
  
  	return (a & 0xFFFFFFFF) ^ (BITS_PER_LONG > 32 ? a >> 32 : 0);
  }

  static u32 flow_get_src(struct sk_buff *skb)

  {
  	switch (skb->protocol) {

  	case htons(ETH_P_IP):

  		if (pskb_network_may_pull(skb, sizeof(struct iphdr)))
  			return ntohl(ip_hdr(skb)->saddr);
  		break;

  	case htons(ETH_P_IPV6):

  		if (pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
  			return ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]);
  		break;

  	}

  
  	return addr_fold(skb->sk);

  }

  static u32 flow_get_dst(struct sk_buff *skb)

  {
  	switch (skb->protocol) {

  	case htons(ETH_P_IP):

  		if (pskb_network_may_pull(skb, sizeof(struct iphdr)))
  			return ntohl(ip_hdr(skb)->daddr);
  		break;

  	case htons(ETH_P_IPV6):

  		if (pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
  			return ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]);
  		break;

  	}

  
  	return addr_fold(skb_dst(skb)) ^ (__force u16)skb->protocol;

  }

  static u32 flow_get_proto(struct sk_buff *skb)

  {
  	switch (skb->protocol) {

  	case htons(ETH_P_IP):

  		return pskb_network_may_pull(skb, sizeof(struct iphdr)) ?
  		       ip_hdr(skb)->protocol : 0;

  	case htons(ETH_P_IPV6):

  		return pskb_network_may_pull(skb, sizeof(struct ipv6hdr)) ?
  		       ipv6_hdr(skb)->nexthdr : 0;

  	default:
  		return 0;
  	}
  }
  
  static int has_ports(u8 protocol)
  {
  	switch (protocol) {
  	case IPPROTO_TCP:
  	case IPPROTO_UDP:
  	case IPPROTO_UDPLITE:
  	case IPPROTO_SCTP:
  	case IPPROTO_DCCP:
  	case IPPROTO_ESP:
  		return 1;
  	default:
  		return 0;
  	}
  }

  static u32 flow_get_proto_src(struct sk_buff *skb)

  {

  	switch (skb->protocol) {

  	case htons(ETH_P_IP): {

  		struct iphdr *iph;

  		if (!pskb_network_may_pull(skb, sizeof(*iph)))
  			break;
  		iph = ip_hdr(skb);

  		if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&

  		    has_ports(iph->protocol) &&
  		    pskb_network_may_pull(skb, iph->ihl * 4 + 2))
  			return ntohs(*(__be16 *)((void *)iph + iph->ihl * 4));

  		break;
  	}

  	case htons(ETH_P_IPV6): {

  		struct ipv6hdr *iph;

  		if (!pskb_network_may_pull(skb, sizeof(*iph) + 2))
  			break;
  		iph = ipv6_hdr(skb);

  		if (has_ports(iph->nexthdr))

  			return ntohs(*(__be16 *)&iph[1]);

  		break;
  	}

  	}

  	return addr_fold(skb->sk);

  }

  static u32 flow_get_proto_dst(struct sk_buff *skb)

  {

  	switch (skb->protocol) {

  	case htons(ETH_P_IP): {

  		struct iphdr *iph;

  		if (!pskb_network_may_pull(skb, sizeof(*iph)))
  			break;
  		iph = ip_hdr(skb);

  		if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&

  		    has_ports(iph->protocol) &&
  		    pskb_network_may_pull(skb, iph->ihl * 4 + 4))
  			return ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 + 2));

  		break;
  	}

  	case htons(ETH_P_IPV6): {

  		struct ipv6hdr *iph;

  		if (!pskb_network_may_pull(skb, sizeof(*iph) + 4))
  			break;
  		iph = ipv6_hdr(skb);

  		if (has_ports(iph->nexthdr))

  			return ntohs(*(__be16 *)((void *)&iph[1] + 2));

  		break;
  	}

  	}

  	return addr_fold(skb_dst(skb)) ^ (__force u16)skb->protocol;

  }
  
  static u32 flow_get_iif(const struct sk_buff *skb)
  {

  	return skb->skb_iif;

  }
  
  static u32 flow_get_priority(const struct sk_buff *skb)
  {
  	return skb->priority;
  }
  
  static u32 flow_get_mark(const struct sk_buff *skb)
  {
  	return skb->mark;
  }
  
  static u32 flow_get_nfct(const struct sk_buff *skb)
  {
  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  	return addr_fold(skb->nfct);
  #else
  	return 0;
  #endif
  }
  
  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  #define CTTUPLE(skb, member)						\
  ({									\
  	enum ip_conntrack_info ctinfo;					\
  	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);			\
  	if (ct == NULL)							\
  		goto fallback;						\
  	ct->tuplehash[CTINFO2DIR(ctinfo)].tuple.member;			\
  })
  #else
  #define CTTUPLE(skb, member)						\
  ({									\
  	goto fallback;							\
  	0;								\
  })
  #endif

  static u32 flow_get_nfct_src(struct sk_buff *skb)

  {
  	switch (skb->protocol) {

  	case htons(ETH_P_IP):

  		return ntohl(CTTUPLE(skb, src.u3.ip));

  	case htons(ETH_P_IPV6):

  		return ntohl(CTTUPLE(skb, src.u3.ip6[3]));
  	}
  fallback:
  	return flow_get_src(skb);
  }

  static u32 flow_get_nfct_dst(struct sk_buff *skb)

  {
  	switch (skb->protocol) {

  	case htons(ETH_P_IP):

  		return ntohl(CTTUPLE(skb, dst.u3.ip));

  	case htons(ETH_P_IPV6):

  		return ntohl(CTTUPLE(skb, dst.u3.ip6[3]));
  	}
  fallback:
  	return flow_get_dst(skb);
  }

  static u32 flow_get_nfct_proto_src(struct sk_buff *skb)

  {
  	return ntohs(CTTUPLE(skb, src.u.all));
  fallback:
  	return flow_get_proto_src(skb);
  }

  static u32 flow_get_nfct_proto_dst(struct sk_buff *skb)

  {
  	return ntohs(CTTUPLE(skb, dst.u.all));
  fallback:
  	return flow_get_proto_dst(skb);
  }
  
  static u32 flow_get_rtclassid(const struct sk_buff *skb)
  {
  #ifdef CONFIG_NET_CLS_ROUTE

  	if (skb_dst(skb))
  		return skb_dst(skb)->tclassid;

  #endif
  	return 0;
  }
  
  static u32 flow_get_skuid(const struct sk_buff *skb)
  {
  	if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file)

  		return skb->sk->sk_socket->file->f_cred->fsuid;

  	return 0;
  }
  
  static u32 flow_get_skgid(const struct sk_buff *skb)
  {
  	if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file)

  		return skb->sk->sk_socket->file->f_cred->fsgid;

  	return 0;
  }

  static u32 flow_get_vlan_tag(const struct sk_buff *skb)
  {
  	u16 uninitialized_var(tag);
  
  	if (vlan_get_tag(skb, &tag) < 0)
  		return 0;
  	return tag & VLAN_VID_MASK;
  }

  static u32 flow_key_get(struct sk_buff *skb, int key)

  {
  	switch (key) {
  	case FLOW_KEY_SRC:
  		return flow_get_src(skb);
  	case FLOW_KEY_DST:
  		return flow_get_dst(skb);
  	case FLOW_KEY_PROTO:
  		return flow_get_proto(skb);
  	case FLOW_KEY_PROTO_SRC:
  		return flow_get_proto_src(skb);
  	case FLOW_KEY_PROTO_DST:
  		return flow_get_proto_dst(skb);
  	case FLOW_KEY_IIF:
  		return flow_get_iif(skb);
  	case FLOW_KEY_PRIORITY:
  		return flow_get_priority(skb);
  	case FLOW_KEY_MARK:
  		return flow_get_mark(skb);
  	case FLOW_KEY_NFCT:
  		return flow_get_nfct(skb);
  	case FLOW_KEY_NFCT_SRC:
  		return flow_get_nfct_src(skb);
  	case FLOW_KEY_NFCT_DST:
  		return flow_get_nfct_dst(skb);
  	case FLOW_KEY_NFCT_PROTO_SRC:
  		return flow_get_nfct_proto_src(skb);
  	case FLOW_KEY_NFCT_PROTO_DST:
  		return flow_get_nfct_proto_dst(skb);
  	case FLOW_KEY_RTCLASSID:
  		return flow_get_rtclassid(skb);
  	case FLOW_KEY_SKUID:
  		return flow_get_skuid(skb);
  	case FLOW_KEY_SKGID:
  		return flow_get_skgid(skb);

  	case FLOW_KEY_VLAN_TAG:
  		return flow_get_vlan_tag(skb);

  	default:
  		WARN_ON(1);
  		return 0;
  	}
  }
  
  static int flow_classify(struct sk_buff *skb, struct tcf_proto *tp,
  			 struct tcf_result *res)
  {
  	struct flow_head *head = tp->root;
  	struct flow_filter *f;
  	u32 keymask;
  	u32 classid;
  	unsigned int n, key;
  	int r;
  
  	list_for_each_entry(f, &head->filters, list) {
  		u32 keys[f->nkeys];
  
  		if (!tcf_em_tree_match(skb, &f->ematches, NULL))
  			continue;
  
  		keymask = f->keymask;
  
  		for (n = 0; n < f->nkeys; n++) {
  			key = ffs(keymask) - 1;
  			keymask &= ~(1 << key);
  			keys[n] = flow_key_get(skb, key);
  		}
  
  		if (f->mode == FLOW_MODE_HASH)

  			classid = jhash2(keys, f->nkeys, f->hashrnd);

  		else {
  			classid = keys[0];
  			classid = (classid & f->mask) ^ f->xor;
  			classid = (classid >> f->rshift) + f->addend;
  		}
  
  		if (f->divisor)
  			classid %= f->divisor;
  
  		res->class   = 0;
  		res->classid = TC_H_MAKE(f->baseclass, f->baseclass + classid);
  
  		r = tcf_exts_exec(skb, &f->exts, res);
  		if (r < 0)
  			continue;
  		return r;
  	}
  	return -1;
  }

  static void flow_perturbation(unsigned long arg)
  {
  	struct flow_filter *f = (struct flow_filter *)arg;
  
  	get_random_bytes(&f->hashrnd, 4);
  	if (f->perturb_period)
  		mod_timer(&f->perturb_timer, jiffies + f->perturb_period);
  }

  static const struct nla_policy flow_policy[TCA_FLOW_MAX + 1] = {
  	[TCA_FLOW_KEYS]		= { .type = NLA_U32 },
  	[TCA_FLOW_MODE]		= { .type = NLA_U32 },
  	[TCA_FLOW_BASECLASS]	= { .type = NLA_U32 },
  	[TCA_FLOW_RSHIFT]	= { .type = NLA_U32 },
  	[TCA_FLOW_ADDEND]	= { .type = NLA_U32 },
  	[TCA_FLOW_MASK]		= { .type = NLA_U32 },
  	[TCA_FLOW_XOR]		= { .type = NLA_U32 },
  	[TCA_FLOW_DIVISOR]	= { .type = NLA_U32 },
  	[TCA_FLOW_ACT]		= { .type = NLA_NESTED },
  	[TCA_FLOW_POLICE]	= { .type = NLA_NESTED },
  	[TCA_FLOW_EMATCHES]	= { .type = NLA_NESTED },

  	[TCA_FLOW_PERTURB]	= { .type = NLA_U32 },

  };
  
  static int flow_change(struct tcf_proto *tp, unsigned long base,
  		       u32 handle, struct nlattr **tca,
  		       unsigned long *arg)
  {
  	struct flow_head *head = tp->root;
  	struct flow_filter *f;
  	struct nlattr *opt = tca[TCA_OPTIONS];
  	struct nlattr *tb[TCA_FLOW_MAX + 1];
  	struct tcf_exts e;
  	struct tcf_ematch_tree t;
  	unsigned int nkeys = 0;

  	unsigned int perturb_period = 0;

  	u32 baseclass = 0;
  	u32 keymask = 0;
  	u32 mode;
  	int err;
  
  	if (opt == NULL)
  		return -EINVAL;
  
  	err = nla_parse_nested(tb, TCA_FLOW_MAX, opt, flow_policy);
  	if (err < 0)
  		return err;
  
  	if (tb[TCA_FLOW_BASECLASS]) {
  		baseclass = nla_get_u32(tb[TCA_FLOW_BASECLASS]);
  		if (TC_H_MIN(baseclass) == 0)
  			return -EINVAL;
  	}
  
  	if (tb[TCA_FLOW_KEYS]) {
  		keymask = nla_get_u32(tb[TCA_FLOW_KEYS]);

  
  		nkeys = hweight32(keymask);
  		if (nkeys == 0)
  			return -EINVAL;

  
  		if (fls(keymask) - 1 > FLOW_KEY_MAX)
  			return -EOPNOTSUPP;

  	}
  
  	err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &flow_ext_map);
  	if (err < 0)
  		return err;
  
  	err = tcf_em_tree_validate(tp, tb[TCA_FLOW_EMATCHES], &t);
  	if (err < 0)
  		goto err1;
  
  	f = (struct flow_filter *)*arg;
  	if (f != NULL) {
  		err = -EINVAL;
  		if (f->handle != handle && handle)
  			goto err2;
  
  		mode = f->mode;
  		if (tb[TCA_FLOW_MODE])
  			mode = nla_get_u32(tb[TCA_FLOW_MODE]);
  		if (mode != FLOW_MODE_HASH && nkeys > 1)
  			goto err2;

  
  		if (mode == FLOW_MODE_HASH)
  			perturb_period = f->perturb_period;
  		if (tb[TCA_FLOW_PERTURB]) {
  			if (mode != FLOW_MODE_HASH)
  				goto err2;
  			perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
  		}

  	} else {
  		err = -EINVAL;
  		if (!handle)
  			goto err2;
  		if (!tb[TCA_FLOW_KEYS])
  			goto err2;
  
  		mode = FLOW_MODE_MAP;
  		if (tb[TCA_FLOW_MODE])
  			mode = nla_get_u32(tb[TCA_FLOW_MODE]);
  		if (mode != FLOW_MODE_HASH && nkeys > 1)
  			goto err2;

  		if (tb[TCA_FLOW_PERTURB]) {
  			if (mode != FLOW_MODE_HASH)
  				goto err2;
  			perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
  		}

  		if (TC_H_MAJ(baseclass) == 0)
  			baseclass = TC_H_MAKE(tp->q->handle, baseclass);
  		if (TC_H_MIN(baseclass) == 0)
  			baseclass = TC_H_MAKE(baseclass, 1);
  
  		err = -ENOBUFS;
  		f = kzalloc(sizeof(*f), GFP_KERNEL);
  		if (f == NULL)
  			goto err2;
  
  		f->handle = handle;
  		f->mask	  = ~0U;

  
  		get_random_bytes(&f->hashrnd, 4);
  		f->perturb_timer.function = flow_perturbation;
  		f->perturb_timer.data = (unsigned long)f;
  		init_timer_deferrable(&f->perturb_timer);

  	}
  
  	tcf_exts_change(tp, &f->exts, &e);
  	tcf_em_tree_change(tp, &f->ematches, &t);
  
  	tcf_tree_lock(tp);
  
  	if (tb[TCA_FLOW_KEYS]) {
  		f->keymask = keymask;
  		f->nkeys   = nkeys;
  	}
  
  	f->mode = mode;
  
  	if (tb[TCA_FLOW_MASK])
  		f->mask = nla_get_u32(tb[TCA_FLOW_MASK]);
  	if (tb[TCA_FLOW_XOR])
  		f->xor = nla_get_u32(tb[TCA_FLOW_XOR]);
  	if (tb[TCA_FLOW_RSHIFT])
  		f->rshift = nla_get_u32(tb[TCA_FLOW_RSHIFT]);
  	if (tb[TCA_FLOW_ADDEND])
  		f->addend = nla_get_u32(tb[TCA_FLOW_ADDEND]);
  
  	if (tb[TCA_FLOW_DIVISOR])
  		f->divisor = nla_get_u32(tb[TCA_FLOW_DIVISOR]);
  	if (baseclass)
  		f->baseclass = baseclass;

  	f->perturb_period = perturb_period;
  	del_timer(&f->perturb_timer);
  	if (perturb_period)
  		mod_timer(&f->perturb_timer, jiffies + perturb_period);

  	if (*arg == 0)
  		list_add_tail(&f->list, &head->filters);
  
  	tcf_tree_unlock(tp);
  
  	*arg = (unsigned long)f;
  	return 0;
  
  err2:
  	tcf_em_tree_destroy(tp, &t);
  err1:
  	tcf_exts_destroy(tp, &e);
  	return err;
  }
  
  static void flow_destroy_filter(struct tcf_proto *tp, struct flow_filter *f)
  {

  	del_timer_sync(&f->perturb_timer);

  	tcf_exts_destroy(tp, &f->exts);
  	tcf_em_tree_destroy(tp, &f->ematches);
  	kfree(f);
  }
  
  static int flow_delete(struct tcf_proto *tp, unsigned long arg)
  {
  	struct flow_filter *f = (struct flow_filter *)arg;
  
  	tcf_tree_lock(tp);
  	list_del(&f->list);
  	tcf_tree_unlock(tp);
  	flow_destroy_filter(tp, f);
  	return 0;
  }
  
  static int flow_init(struct tcf_proto *tp)
  {
  	struct flow_head *head;

  	head = kzalloc(sizeof(*head), GFP_KERNEL);
  	if (head == NULL)
  		return -ENOBUFS;
  	INIT_LIST_HEAD(&head->filters);
  	tp->root = head;
  	return 0;
  }
  
  static void flow_destroy(struct tcf_proto *tp)
  {
  	struct flow_head *head = tp->root;
  	struct flow_filter *f, *next;
  
  	list_for_each_entry_safe(f, next, &head->filters, list) {
  		list_del(&f->list);
  		flow_destroy_filter(tp, f);
  	}
  	kfree(head);
  }
  
  static unsigned long flow_get(struct tcf_proto *tp, u32 handle)
  {
  	struct flow_head *head = tp->root;
  	struct flow_filter *f;
  
  	list_for_each_entry(f, &head->filters, list)
  		if (f->handle == handle)
  			return (unsigned long)f;
  	return 0;
  }
  
  static void flow_put(struct tcf_proto *tp, unsigned long f)
  {

  }
  
  static int flow_dump(struct tcf_proto *tp, unsigned long fh,
  		     struct sk_buff *skb, struct tcmsg *t)
  {
  	struct flow_filter *f = (struct flow_filter *)fh;
  	struct nlattr *nest;
  
  	if (f == NULL)
  		return skb->len;
  
  	t->tcm_handle = f->handle;
  
  	nest = nla_nest_start(skb, TCA_OPTIONS);
  	if (nest == NULL)
  		goto nla_put_failure;
  
  	NLA_PUT_U32(skb, TCA_FLOW_KEYS, f->keymask);
  	NLA_PUT_U32(skb, TCA_FLOW_MODE, f->mode);
  
  	if (f->mask != ~0 || f->xor != 0) {
  		NLA_PUT_U32(skb, TCA_FLOW_MASK, f->mask);
  		NLA_PUT_U32(skb, TCA_FLOW_XOR, f->xor);
  	}
  	if (f->rshift)
  		NLA_PUT_U32(skb, TCA_FLOW_RSHIFT, f->rshift);
  	if (f->addend)
  		NLA_PUT_U32(skb, TCA_FLOW_ADDEND, f->addend);
  
  	if (f->divisor)
  		NLA_PUT_U32(skb, TCA_FLOW_DIVISOR, f->divisor);
  	if (f->baseclass)
  		NLA_PUT_U32(skb, TCA_FLOW_BASECLASS, f->baseclass);

  	if (f->perturb_period)
  		NLA_PUT_U32(skb, TCA_FLOW_PERTURB, f->perturb_period / HZ);

  	if (tcf_exts_dump(skb, &f->exts, &flow_ext_map) < 0)
  		goto nla_put_failure;

  #ifdef CONFIG_NET_EMATCH

  	if (f->ematches.hdr.nmatches &&
  	    tcf_em_tree_dump(skb, &f->ematches, TCA_FLOW_EMATCHES) < 0)
  		goto nla_put_failure;

  #endif

  	nla_nest_end(skb, nest);
  
  	if (tcf_exts_dump_stats(skb, &f->exts, &flow_ext_map) < 0)
  		goto nla_put_failure;
  
  	return skb->len;
  
  nla_put_failure:
  	nlmsg_trim(skb, nest);
  	return -1;
  }
  
  static void flow_walk(struct tcf_proto *tp, struct tcf_walker *arg)
  {
  	struct flow_head *head = tp->root;
  	struct flow_filter *f;
  
  	list_for_each_entry(f, &head->filters, list) {
  		if (arg->count < arg->skip)
  			goto skip;
  		if (arg->fn(tp, (unsigned long)f, arg) < 0) {
  			arg->stop = 1;
  			break;
  		}
  skip:
  		arg->count++;
  	}
  }
  
  static struct tcf_proto_ops cls_flow_ops __read_mostly = {
  	.kind		= "flow",
  	.classify	= flow_classify,
  	.init		= flow_init,
  	.destroy	= flow_destroy,
  	.change		= flow_change,
  	.delete		= flow_delete,
  	.get		= flow_get,
  	.put		= flow_put,
  	.dump		= flow_dump,
  	.walk		= flow_walk,
  	.owner		= THIS_MODULE,
  };
  
  static int __init cls_flow_init(void)
  {
  	return register_tcf_proto_ops(&cls_flow_ops);
  }
  
  static void __exit cls_flow_exit(void)
  {
  	unregister_tcf_proto_ops(&cls_flow_ops);
  }
  
  module_init(cls_flow_init);
  module_exit(cls_flow_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  MODULE_DESCRIPTION("TC flow classifier");