/*
   *	DCCP over IPv6

   *	Linux INET6 implementation

   *
   *	Based on net/dccp6/ipv6.c
   *
   *	Arnaldo Carvalho de Melo <acme@ghostprotocols.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/module.h>
  #include <linux/random.h>

  #include <linux/slab.h>

  #include <linux/xfrm.h>
  
  #include <net/addrconf.h>
  #include <net/inet_common.h>
  #include <net/inet_hashtables.h>

  #include <net/inet_sock.h>

  #include <net/inet6_connection_sock.h>
  #include <net/inet6_hashtables.h>
  #include <net/ip6_route.h>
  #include <net/ipv6.h>
  #include <net/protocol.h>
  #include <net/transp_v6.h>

  #include <net/ip6_checksum.h>

  #include <net/xfrm.h>

  #include <net/secure_seq.h>

  
  #include "dccp.h"
  #include "ipv6.h"

  #include "feat.h"

  /* The per-net dccp.v6_ctl_sk is used for sending RSTs and ACKs */

  static const struct inet_connection_sock_af_ops dccp_ipv6_mapped;
  static const struct inet_connection_sock_af_ops dccp_ipv6_af_ops;

  static void dccp_v6_hash(struct sock *sk)
  {
  	if (sk->sk_state != DCCP_CLOSED) {
  		if (inet_csk(sk)->icsk_af_ops == &dccp_ipv6_mapped) {

  			inet_hash(sk);

  			return;
  		}
  		local_bh_disable();

  		__inet6_hash(sk, NULL);

  		local_bh_enable();
  	}
  }

  /* add pseudo-header to DCCP checksum stored in skb->csum */

  static inline __sum16 dccp_v6_csum_finish(struct sk_buff *skb,

  				      const struct in6_addr *saddr,
  				      const struct in6_addr *daddr)

  {

  	return csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_DCCP, skb->csum);
  }

  static inline void dccp_v6_send_check(struct sock *sk, struct sk_buff *skb)

  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct dccp_hdr *dh = dccp_hdr(skb);
  
  	dccp_csum_outgoing(skb);
  	dh->dccph_checksum = dccp_v6_csum_finish(skb, &np->saddr, &np->daddr);

  }

  static inline __u64 dccp_v6_init_sequence(struct sk_buff *skb)

  {

  	return secure_dccpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32,
  					     ipv6_hdr(skb)->saddr.s6_addr32,

  					     dccp_hdr(skb)->dccph_dport,
  					     dccp_hdr(skb)->dccph_sport     );

  }

  static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

  			u8 type, u8 code, int offset, __be32 info)

  {

  	const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;

  	const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);

  	struct dccp_sock *dp;

  	struct ipv6_pinfo *np;
  	struct sock *sk;
  	int err;
  	__u64 seq;

  	struct net *net = dev_net(skb->dev);

  	if (skb->len < offset + sizeof(*dh) ||
  	    skb->len < offset + __dccp_basic_hdr_len(dh)) {

  		ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
  				   ICMP6_MIB_INERRORS);

  		return;
  	}

  	sk = inet6_lookup(net, &dccp_hashinfo,

  			&hdr->daddr, dh->dccph_dport,

  			&hdr->saddr, dh->dccph_sport, inet6_iif(skb));

  
  	if (sk == NULL) {

  		ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
  				   ICMP6_MIB_INERRORS);

  		return;
  	}
  
  	if (sk->sk_state == DCCP_TIME_WAIT) {

  		inet_twsk_put(inet_twsk(sk));

  		return;
  	}
  
  	bh_lock_sock(sk);
  	if (sock_owned_by_user(sk))

  		NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);

  
  	if (sk->sk_state == DCCP_CLOSED)
  		goto out;

  	dp = dccp_sk(sk);
  	seq = dccp_hdr_seq(dh);
  	if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
  	    !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
  		NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
  		goto out;
  	}

  	np = inet6_sk(sk);

  	if (type == NDISC_REDIRECT) {
  		struct dst_entry *dst = __sk_dst_check(sk, np->dst_cookie);

  		if (dst)

  			dst->ops->redirect(dst, sk, skb);

  		goto out;

  	}

  	if (type == ICMPV6_PKT_TOOBIG) {

  		struct dst_entry *dst = NULL;
  
  		if (sock_owned_by_user(sk))
  			goto out;
  		if ((1 << sk->sk_state) & (DCCPF_LISTEN | DCCPF_CLOSED))
  			goto out;

  		dst = inet6_csk_update_pmtu(sk, ntohl(info));
  		if (!dst)
  			goto out;
  
  		if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst))

  			dccp_sync_mss(sk, dst_mtu(dst));

  		goto out;
  	}
  
  	icmpv6_err_convert(type, code, &err);

  	/* Might be for an request_sock */
  	switch (sk->sk_state) {
  		struct request_sock *req, **prev;
  	case DCCP_LISTEN:
  		if (sock_owned_by_user(sk))
  			goto out;
  
  		req = inet6_csk_search_req(sk, &prev, dh->dccph_dport,
  					   &hdr->daddr, &hdr->saddr,
  					   inet6_iif(skb));

  		if (req == NULL)

  			goto out;

  		/*
  		 * ICMPs are not backlogged, hence we cannot get an established
  		 * socket here.

  		 */

  		WARN_ON(req->sk != NULL);

  		if (!between48(seq, dccp_rsk(req)->dreq_iss,
  				    dccp_rsk(req)->dreq_gss)) {

  			NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);

  			goto out;
  		}
  
  		inet_csk_reqsk_queue_drop(sk, req, prev);
  		goto out;
  
  	case DCCP_REQUESTING:
  	case DCCP_RESPOND:  /* Cannot happen.

  			       It can, it SYNs are crossed. --ANK */

  		if (!sock_owned_by_user(sk)) {
  			DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
  			sk->sk_err = err;
  			/*
  			 * Wake people up to see the error
  			 * (see connect in sock.c)
  			 */
  			sk->sk_error_report(sk);

  			dccp_done(sk);
  		} else
  			sk->sk_err_soft = err;
  		goto out;
  	}
  
  	if (!sock_owned_by_user(sk) && np->recverr) {
  		sk->sk_err = err;
  		sk->sk_error_report(sk);
  	} else
  		sk->sk_err_soft = err;
  
  out:
  	bh_unlock_sock(sk);
  	sock_put(sk);
  }

  static int dccp_v6_send_response(struct sock *sk, struct request_sock *req)

  {
  	struct inet6_request_sock *ireq6 = inet6_rsk(req);
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct sk_buff *skb;

  	struct in6_addr *final_p, final;

  	struct flowi6 fl6;

  	int err = -1;

  	struct dst_entry *dst;

  	memset(&fl6, 0, sizeof(fl6));
  	fl6.flowi6_proto = IPPROTO_DCCP;

  	fl6.daddr = ireq6->rmt_addr;
  	fl6.saddr = ireq6->loc_addr;

  	fl6.flowlabel = 0;
  	fl6.flowi6_oif = ireq6->iif;

  	fl6.fl6_dport = inet_rsk(req)->rmt_port;
  	fl6.fl6_sport = inet_rsk(req)->loc_port;

  	security_req_classify_flow(req, flowi6_to_flowi(&fl6));

  	final_p = fl6_update_dst(&fl6, np->opt, &final);

  	dst = ip6_dst_lookup_flow(sk, &fl6, final_p, false);

  	if (IS_ERR(dst)) {
  		err = PTR_ERR(dst);
  		dst = NULL;

  		goto done;

  	}

  
  	skb = dccp_make_response(sk, dst, req);
  	if (skb != NULL) {
  		struct dccp_hdr *dh = dccp_hdr(skb);

  		dh->dccph_checksum = dccp_v6_csum_finish(skb,
  							 &ireq6->loc_addr,
  							 &ireq6->rmt_addr);

  		fl6.daddr = ireq6->rmt_addr;

  		err = ip6_xmit(sk, skb, &fl6, np->opt, np->tclass);

  		err = net_xmit_eval(err);

  	}
  
  done:

  	dst_release(dst);

  	return err;
  }
  
  static void dccp_v6_reqsk_destructor(struct request_sock *req)
  {

  	dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);

  	if (inet6_rsk(req)->pktopts != NULL)
  		kfree_skb(inet6_rsk(req)->pktopts);
  }

  static void dccp_v6_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)

  {

  	const struct ipv6hdr *rxip6h;

  	struct sk_buff *skb;

  	struct flowi6 fl6;

  	struct net *net = dev_net(skb_dst(rxskb)->dev);

  	struct sock *ctl_sk = net->dccp.v6_ctl_sk;

  	struct dst_entry *dst;

  	if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)

  		return;
  
  	if (!ipv6_unicast_destination(rxskb))

  		return;

  	skb = dccp_ctl_make_reset(ctl_sk, rxskb);

  	if (skb == NULL)

  		return;

  	rxip6h = ipv6_hdr(rxskb);

  	dccp_hdr(skb)->dccph_checksum = dccp_v6_csum_finish(skb, &rxip6h->saddr,
  							    &rxip6h->daddr);

  	memset(&fl6, 0, sizeof(fl6));

  	fl6.daddr = rxip6h->saddr;
  	fl6.saddr = rxip6h->daddr;

  	fl6.flowi6_proto = IPPROTO_DCCP;
  	fl6.flowi6_oif = inet6_iif(rxskb);

  	fl6.fl6_dport = dccp_hdr(skb)->dccph_dport;
  	fl6.fl6_sport = dccp_hdr(skb)->dccph_sport;

  	security_skb_classify_flow(rxskb, flowi6_to_flowi(&fl6));

  
  	/* sk = NULL, but it is safe for now. RST socket required. */

  	dst = ip6_dst_lookup_flow(ctl_sk, &fl6, NULL, false);

  	if (!IS_ERR(dst)) {
  		skb_dst_set(skb, dst);

  		ip6_xmit(ctl_sk, skb, &fl6, NULL, 0);

  		DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
  		DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
  		return;

  	}
  
  	kfree_skb(skb);
  }

  static struct request_sock_ops dccp6_request_sock_ops = {
  	.family		= AF_INET6,
  	.obj_size	= sizeof(struct dccp6_request_sock),
  	.rtx_syn_ack	= dccp_v6_send_response,
  	.send_ack	= dccp_reqsk_send_ack,
  	.destructor	= dccp_v6_reqsk_destructor,
  	.send_reset	= dccp_v6_ctl_send_reset,

  	.syn_ack_timeout = dccp_syn_ack_timeout,

  };

  static struct sock *dccp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
  {
  	const struct dccp_hdr *dh = dccp_hdr(skb);

  	const struct ipv6hdr *iph = ipv6_hdr(skb);

  	struct sock *nsk;
  	struct request_sock **prev;
  	/* Find possible connection requests. */
  	struct request_sock *req = inet6_csk_search_req(sk, &prev,
  							dh->dccph_sport,
  							&iph->saddr,
  							&iph->daddr,
  							inet6_iif(skb));
  	if (req != NULL)
  		return dccp_check_req(sk, skb, req, prev);

  	nsk = __inet6_lookup_established(sock_net(sk), &dccp_hashinfo,

  					 &iph->saddr, dh->dccph_sport,
  					 &iph->daddr, ntohs(dh->dccph_dport),
  					 inet6_iif(skb));

  	if (nsk != NULL) {
  		if (nsk->sk_state != DCCP_TIME_WAIT) {
  			bh_lock_sock(nsk);
  			return nsk;
  		}

  		inet_twsk_put(inet_twsk(nsk));

  		return NULL;
  	}
  
  	return sk;
  }
  
  static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
  {

  	struct request_sock *req;
  	struct dccp_request_sock *dreq;
  	struct inet6_request_sock *ireq6;
  	struct ipv6_pinfo *np = inet6_sk(sk);

  	const __be32 service = dccp_hdr_request(skb)->dccph_req_service;

  	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);

  
  	if (skb->protocol == htons(ETH_P_IP))
  		return dccp_v4_conn_request(sk, skb);
  
  	if (!ipv6_unicast_destination(skb))

  		return 0;	/* discard, don't send a reset here */

  
  	if (dccp_bad_service_code(sk, service)) {

  		dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;

  		goto drop;

  	}

  	/*

  	 * There are no SYN attacks on IPv6, yet...

  	 */

  	dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;

  	if (inet_csk_reqsk_queue_is_full(sk))

  		goto drop;

  
  	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
  		goto drop;

  	req = inet6_reqsk_alloc(&dccp6_request_sock_ops);

  	if (req == NULL)
  		goto drop;

  	if (dccp_reqsk_init(req, dccp_sk(sk), skb))
  		goto drop_and_free;

  	dreq = dccp_rsk(req);
  	if (dccp_parse_options(sk, dreq, skb))
  		goto drop_and_free;

  	if (security_inet_conn_request(sk, skb, req))
  		goto drop_and_free;

  	ireq6 = inet6_rsk(req);

  	ireq6->rmt_addr = ipv6_hdr(skb)->saddr;
  	ireq6->loc_addr = ipv6_hdr(skb)->daddr;

  
  	if (ipv6_opt_accepted(sk, skb) ||
  	    np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
  	    np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) {
  		atomic_inc(&skb->users);
  		ireq6->pktopts = skb;
  	}
  	ireq6->iif = sk->sk_bound_dev_if;
  
  	/* So that link locals have meaning */
  	if (!sk->sk_bound_dev_if &&
  	    ipv6_addr_type(&ireq6->rmt_addr) & IPV6_ADDR_LINKLOCAL)
  		ireq6->iif = inet6_iif(skb);

  	/*

  	 * Step 3: Process LISTEN state
  	 *

  	 *   Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie

  	 *

  	 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().

  	 */

  	dreq->dreq_isr	   = dcb->dccpd_seq;

  	dreq->dreq_gsr     = dreq->dreq_isr;

  	dreq->dreq_iss	   = dccp_v6_init_sequence(skb);

  	dreq->dreq_gss     = dreq->dreq_iss;

  	dreq->dreq_service = service;

  	if (dccp_v6_send_response(sk, req))

  		goto drop_and_free;
  
  	inet6_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
  	return 0;
  
  drop_and_free:
  	reqsk_free(req);
  drop:
  	DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);

  	return -1;
  }
  
  static struct sock *dccp_v6_request_recv_sock(struct sock *sk,
  					      struct sk_buff *skb,
  					      struct request_sock *req,
  					      struct dst_entry *dst)
  {
  	struct inet6_request_sock *ireq6 = inet6_rsk(req);
  	struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
  	struct inet_sock *newinet;

  	struct dccp6_sock *newdp6;
  	struct sock *newsk;

  
  	if (skb->protocol == htons(ETH_P_IP)) {
  		/*
  		 *	v6 mapped
  		 */

  		newsk = dccp_v4_request_recv_sock(sk, skb, req, dst);

  		if (newsk == NULL)

  			return NULL;
  
  		newdp6 = (struct dccp6_sock *)newsk;

  		newinet = inet_sk(newsk);
  		newinet->pinet6 = &newdp6->inet6;
  		newnp = inet6_sk(newsk);
  
  		memcpy(newnp, np, sizeof(struct ipv6_pinfo));

  		ipv6_addr_set_v4mapped(newinet->inet_daddr, &newnp->daddr);

  		ipv6_addr_set_v4mapped(newinet->inet_saddr, &newnp->saddr);

  		newnp->rcv_saddr = newnp->saddr;

  
  		inet_csk(newsk)->icsk_af_ops = &dccp_ipv6_mapped;
  		newsk->sk_backlog_rcv = dccp_v4_do_rcv;
  		newnp->pktoptions  = NULL;
  		newnp->opt	   = NULL;
  		newnp->mcast_oif   = inet6_iif(skb);

  		newnp->mcast_hops  = ipv6_hdr(skb)->hop_limit;

  
  		/*
  		 * No need to charge this sock to the relevant IPv6 refcnt debug socks count
  		 * here, dccp_create_openreq_child now does this for us, see the comment in
  		 * that function for the gory details. -acme
  		 */
  
  		/* It is tricky place. Until this moment IPv4 tcp
  		   worked with IPv6 icsk.icsk_af_ops.
  		   Sync it now.
  		 */

  		dccp_sync_mss(newsk, inet_csk(newsk)->icsk_pmtu_cookie);

  
  		return newsk;
  	}

  
  	if (sk_acceptq_is_full(sk))
  		goto out_overflow;

  	if (dst == NULL) {

  		struct in6_addr *final_p, final;

  		struct flowi6 fl6;
  
  		memset(&fl6, 0, sizeof(fl6));
  		fl6.flowi6_proto = IPPROTO_DCCP;

  		fl6.daddr = ireq6->rmt_addr;

  		final_p = fl6_update_dst(&fl6, np->opt, &final);

  		fl6.saddr = ireq6->loc_addr;

  		fl6.flowi6_oif = sk->sk_bound_dev_if;

  		fl6.fl6_dport = inet_rsk(req)->rmt_port;
  		fl6.fl6_sport = inet_rsk(req)->loc_port;

  		security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
  
  		dst = ip6_dst_lookup_flow(sk, &fl6, final_p, false);

  		if (IS_ERR(dst))

  			goto out;

  	}

  
  	newsk = dccp_create_openreq_child(sk, req, skb);
  	if (newsk == NULL)

  		goto out_nonewsk;

  
  	/*
  	 * No need to charge this sock to the relevant IPv6 refcnt debug socks
  	 * count here, dccp_create_openreq_child now does this for us, see the
  	 * comment in that function for the gory details. -acme
  	 */

  	__ip6_dst_store(newsk, dst, NULL, NULL);

  	newsk->sk_route_caps = dst->dev->features & ~(NETIF_F_IP_CSUM |
  						      NETIF_F_TSO);

  	newdp6 = (struct dccp6_sock *)newsk;
  	newinet = inet_sk(newsk);
  	newinet->pinet6 = &newdp6->inet6;

  	newnp = inet6_sk(newsk);
  
  	memcpy(newnp, np, sizeof(struct ipv6_pinfo));

  	newnp->daddr = ireq6->rmt_addr;
  	newnp->saddr = ireq6->loc_addr;
  	newnp->rcv_saddr = ireq6->loc_addr;

  	newsk->sk_bound_dev_if = ireq6->iif;

  	/* Now IPv6 options...

  
  	   First: no IPv4 options.
  	 */

  	newinet->inet_opt = NULL;

  
  	/* Clone RX bits */
  	newnp->rxopt.all = np->rxopt.all;
  
  	/* Clone pktoptions received with SYN */
  	newnp->pktoptions = NULL;
  	if (ireq6->pktopts != NULL) {
  		newnp->pktoptions = skb_clone(ireq6->pktopts, GFP_ATOMIC);

  		consume_skb(ireq6->pktopts);

  		ireq6->pktopts = NULL;
  		if (newnp->pktoptions)
  			skb_set_owner_r(newnp->pktoptions, newsk);
  	}
  	newnp->opt	  = NULL;
  	newnp->mcast_oif  = inet6_iif(skb);

  	newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;

  	/*
  	 * Clone native IPv6 options from listening socket (if any)
  	 *
  	 * Yes, keeping reference count would be much more clever, but we make
  	 * one more one thing there: reattach optmem to newsk.

  	 */

  	if (np->opt != NULL)
  		newnp->opt = ipv6_dup_options(newsk, np->opt);

  	inet_csk(newsk)->icsk_ext_hdr_len = 0;

  	if (newnp->opt != NULL)

  		inet_csk(newsk)->icsk_ext_hdr_len = (newnp->opt->opt_nflen +
  						     newnp->opt->opt_flen);

  
  	dccp_sync_mss(newsk, dst_mtu(dst));

  	newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6;
  	newinet->inet_rcv_saddr = LOOPBACK4_IPV6;

  	if (__inet_inherit_port(sk, newsk) < 0) {

  		inet_csk_prepare_forced_close(newsk);
  		dccp_done(newsk);

  		goto out;
  	}

  	__inet6_hash(newsk, NULL);

  
  	return newsk;
  
  out_overflow:

  	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);

  out_nonewsk:
  	dst_release(dst);

  out:

  	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);

  	return NULL;
  }
  
  /* The socket must have it's spinlock held when we get
   * here.
   *
   * We have a potential double-lock case here, so even when
   * doing backlog processing we use the BH locking scheme.
   * This is because we cannot sleep with the original spinlock
   * held.
   */
  static int dccp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct sk_buff *opt_skb = NULL;
  
  	/* Imagine: socket is IPv6. IPv4 packet arrives,
  	   goes to IPv4 receive handler and backlogged.
  	   From backlog it always goes here. Kerboom...
  	   Fortunately, dccp_rcv_established and rcv_established
  	   handle them correctly, but it is not case with
  	   dccp_v6_hnd_req and dccp_v6_ctl_send_reset().   --ANK
  	 */
  
  	if (skb->protocol == htons(ETH_P_IP))
  		return dccp_v4_do_rcv(sk, skb);

  	if (sk_filter(sk, skb))

  		goto discard;
  
  	/*

  	 * socket locking is here for SMP purposes as backlog rcv is currently
  	 * called with bh processing disabled.

  	 */
  
  	/* Do Stevens' IPV6_PKTOPTIONS.
  
  	   Yes, guys, it is the only place in our code, where we
  	   may make it not affecting IPv4.
  	   The rest of code is protocol independent,
  	   and I do not like idea to uglify IPv4.
  
  	   Actually, all the idea behind IPV6_PKTOPTIONS
  	   looks not very well thought. For now we latch
  	   options, received in the last packet, enqueued
  	   by tcp. Feel free to propose better solution.

  					       --ANK (980728)

  	 */
  	if (np->rxopt.all)

  	/*
  	 * FIXME: Add handling of IPV6_PKTOPTIONS skb. See the comments below
  	 *        (wrt ipv6_pktopions) and net/ipv6/tcp_ipv6.c for an example.
  	 */

  		opt_skb = skb_clone(skb, GFP_ATOMIC);
  
  	if (sk->sk_state == DCCP_OPEN) { /* Fast path */
  		if (dccp_rcv_established(sk, skb, dccp_hdr(skb), skb->len))
  			goto reset;

  		if (opt_skb) {

  			/* XXX This is where we would goto ipv6_pktoptions. */

  			__kfree_skb(opt_skb);
  		}

  		return 0;
  	}

  	/*
  	 *  Step 3: Process LISTEN state
  	 *     If S.state == LISTEN,
  	 *	 If P.type == Request or P contains a valid Init Cookie option,
  	 *	      (* Must scan the packet's options to check for Init
  	 *		 Cookies.  Only Init Cookies are processed here,
  	 *		 however; other options are processed in Step 8.  This
  	 *		 scan need only be performed if the endpoint uses Init
  	 *		 Cookies *)
  	 *	      (* Generate a new socket and switch to that socket *)
  	 *	      Set S := new socket for this port pair
  	 *	      S.state = RESPOND
  	 *	      Choose S.ISS (initial seqno) or set from Init Cookies
  	 *	      Initialize S.GAR := S.ISS
  	 *	      Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
  	 *	      Continue with S.state == RESPOND
  	 *	      (* A Response packet will be generated in Step 11 *)
  	 *	 Otherwise,
  	 *	      Generate Reset(No Connection) unless P.type == Reset
  	 *	      Drop packet and return
  	 *
  	 * NOTE: the check for the packet types is done in
  	 *	 dccp_rcv_state_process
  	 */

  	if (sk->sk_state == DCCP_LISTEN) {

  		struct sock *nsk = dccp_v6_hnd_req(sk, skb);

  		if (nsk == NULL)
  			goto discard;

  		/*
  		 * Queue it on the new socket if the new socket is active,
  		 * otherwise we just shortcircuit this and continue with
  		 * the new socket..
  		 */

  		if (nsk != sk) {

  			if (dccp_child_process(sk, nsk, skb))
  				goto reset;

  			if (opt_skb != NULL)

  				__kfree_skb(opt_skb);
  			return 0;
  		}
  	}
  
  	if (dccp_rcv_state_process(sk, skb, dccp_hdr(skb), skb->len))
  		goto reset;

  	if (opt_skb) {

  		/* XXX This is where we would goto ipv6_pktoptions. */

  		__kfree_skb(opt_skb);
  	}

  	return 0;
  
  reset:

  	dccp_v6_ctl_send_reset(sk, skb);

  discard:

  	if (opt_skb != NULL)

  		__kfree_skb(opt_skb);
  	kfree_skb(skb);
  	return 0;
  }

  static int dccp_v6_rcv(struct sk_buff *skb)

  {
  	const struct dccp_hdr *dh;

  	struct sock *sk;

  	int min_cov;

  	/* Step 1: Check header basics */

  
  	if (dccp_invalid_packet(skb))
  		goto discard_it;

  	/* Step 1: If header checksum is incorrect, drop packet and return. */

  	if (dccp_v6_csum_finish(skb, &ipv6_hdr(skb)->saddr,
  				     &ipv6_hdr(skb)->daddr)) {

  		DCCP_WARN("dropped packet with invalid checksum
  ");

  		goto discard_it;
  	}

  	dh = dccp_hdr(skb);

  	DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);

  	DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
  
  	if (dccp_packet_without_ack(skb))
  		DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
  	else
  		DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
  
  	/* Step 2:

  	 *	Look up flow ID in table and get corresponding socket */

  	sk = __inet6_lookup_skb(&dccp_hashinfo, skb,
  			        dh->dccph_sport, dh->dccph_dport);

  	/*

  	 * Step 2:

  	 *	If no socket ...

  	 */

  	if (sk == NULL) {
  		dccp_pr_debug("failed to look up flow ID in table and "
  			      "get corresponding socket
  ");

  		goto no_dccp_socket;

  	}

  	/*

  	 * Step 2:

  	 *	... or S.state == TIMEWAIT,

  	 *		Generate Reset(No Connection) unless P.type == Reset
  	 *		Drop packet and return
  	 */

  	if (sk->sk_state == DCCP_TIME_WAIT) {
  		dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait
  ");
  		inet_twsk_put(inet_twsk(sk));
  		goto no_dccp_socket;
  	}

  	/*
  	 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage

  	 *	o if MinCsCov = 0, only packets with CsCov = 0 are accepted
  	 *	o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov

  	 */
  	min_cov = dccp_sk(sk)->dccps_pcrlen;
  	if (dh->dccph_cscov  &&  (min_cov == 0 || dh->dccph_cscov < min_cov))  {
  		dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d
  ",
  			      dh->dccph_cscov, min_cov);
  		/* FIXME: send Data Dropped option (see also dccp_v4_rcv) */
  		goto discard_and_relse;
  	}

  	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
  		goto discard_and_relse;

  	return sk_receive_skb(sk, skb, 1) ? -1 : 0;

  
  no_dccp_socket:
  	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
  		goto discard_it;
  	/*
  	 * Step 2:

  	 *	If no socket ...

  	 *		Generate Reset(No Connection) unless P.type == Reset
  	 *		Drop packet and return
  	 */
  	if (dh->dccph_type != DCCP_PKT_RESET) {
  		DCCP_SKB_CB(skb)->dccpd_reset_code =
  					DCCP_RESET_CODE_NO_CONNECTION;

  		dccp_v6_ctl_send_reset(sk, skb);

  	}

  discard_it:

  	kfree_skb(skb);
  	return 0;
  
  discard_and_relse:
  	sock_put(sk);
  	goto discard_it;

  }

  static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
  			   int addr_len)
  {
  	struct sockaddr_in6 *usin = (struct sockaddr_in6 *)uaddr;
  	struct inet_connection_sock *icsk = inet_csk(sk);
  	struct inet_sock *inet = inet_sk(sk);
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct dccp_sock *dp = dccp_sk(sk);

  	struct in6_addr *saddr = NULL, *final_p, final;

  	struct flowi6 fl6;

  	struct dst_entry *dst;
  	int addr_type;
  	int err;
  
  	dp->dccps_role = DCCP_ROLE_CLIENT;
  
  	if (addr_len < SIN6_LEN_RFC2133)
  		return -EINVAL;
  
  	if (usin->sin6_family != AF_INET6)
  		return -EAFNOSUPPORT;

  	memset(&fl6, 0, sizeof(fl6));

  
  	if (np->sndflow) {

  		fl6.flowlabel = usin->sin6_flowinfo & IPV6_FLOWINFO_MASK;
  		IP6_ECN_flow_init(fl6.flowlabel);
  		if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {

  			struct ip6_flowlabel *flowlabel;

  			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);

  			if (flowlabel == NULL)
  				return -EINVAL;

  			usin->sin6_addr = flowlabel->dst;

  			fl6_sock_release(flowlabel);
  		}
  	}
  	/*
  	 * connect() to INADDR_ANY means loopback (BSD'ism).
  	 */
  	if (ipv6_addr_any(&usin->sin6_addr))
  		usin->sin6_addr.s6_addr[15] = 1;
  
  	addr_type = ipv6_addr_type(&usin->sin6_addr);
  
  	if (addr_type & IPV6_ADDR_MULTICAST)
  		return -ENETUNREACH;
  
  	if (addr_type & IPV6_ADDR_LINKLOCAL) {
  		if (addr_len >= sizeof(struct sockaddr_in6) &&
  		    usin->sin6_scope_id) {
  			/* If interface is set while binding, indices
  			 * must coincide.
  			 */
  			if (sk->sk_bound_dev_if &&
  			    sk->sk_bound_dev_if != usin->sin6_scope_id)
  				return -EINVAL;
  
  			sk->sk_bound_dev_if = usin->sin6_scope_id;
  		}
  
  		/* Connect to link-local address requires an interface */
  		if (!sk->sk_bound_dev_if)
  			return -EINVAL;
  	}

  	np->daddr = usin->sin6_addr;

  	np->flow_label = fl6.flowlabel;

  
  	/*
  	 * DCCP over IPv4
  	 */
  	if (addr_type == IPV6_ADDR_MAPPED) {
  		u32 exthdrlen = icsk->icsk_ext_hdr_len;
  		struct sockaddr_in sin;
  
  		SOCK_DEBUG(sk, "connect: ipv4 mapped
  ");
  
  		if (__ipv6_only_sock(sk))
  			return -ENETUNREACH;
  
  		sin.sin_family = AF_INET;
  		sin.sin_port = usin->sin6_port;
  		sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];
  
  		icsk->icsk_af_ops = &dccp_ipv6_mapped;
  		sk->sk_backlog_rcv = dccp_v4_do_rcv;
  
  		err = dccp_v4_connect(sk, (struct sockaddr *)&sin, sizeof(sin));
  		if (err) {
  			icsk->icsk_ext_hdr_len = exthdrlen;
  			icsk->icsk_af_ops = &dccp_ipv6_af_ops;
  			sk->sk_backlog_rcv = dccp_v6_do_rcv;
  			goto failure;

  		}

  		ipv6_addr_set_v4mapped(inet->inet_saddr, &np->saddr);
  		ipv6_addr_set_v4mapped(inet->inet_rcv_saddr, &np->rcv_saddr);

  
  		return err;
  	}
  
  	if (!ipv6_addr_any(&np->rcv_saddr))
  		saddr = &np->rcv_saddr;

  	fl6.flowi6_proto = IPPROTO_DCCP;

  	fl6.daddr = np->daddr;
  	fl6.saddr = saddr ? *saddr : np->saddr;

  	fl6.flowi6_oif = sk->sk_bound_dev_if;

  	fl6.fl6_dport = usin->sin6_port;
  	fl6.fl6_sport = inet->inet_sport;

  	security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));

  	final_p = fl6_update_dst(&fl6, np->opt, &final);

  	dst = ip6_dst_lookup_flow(sk, &fl6, final_p, true);

  	if (IS_ERR(dst)) {
  		err = PTR_ERR(dst);

  		goto failure;

  	}

  
  	if (saddr == NULL) {

  		saddr = &fl6.saddr;

  		np->rcv_saddr = *saddr;

  	}
  
  	/* set the source address */

  	np->saddr = *saddr;

  	inet->inet_rcv_saddr = LOOPBACK4_IPV6;

  
  	__ip6_dst_store(sk, dst, NULL, NULL);
  
  	icsk->icsk_ext_hdr_len = 0;
  	if (np->opt != NULL)
  		icsk->icsk_ext_hdr_len = (np->opt->opt_flen +
  					  np->opt->opt_nflen);

  	inet->inet_dport = usin->sin6_port;

  
  	dccp_set_state(sk, DCCP_REQUESTING);
  	err = inet6_hash_connect(&dccp_death_row, sk);
  	if (err)
  		goto late_failure;

  
  	dp->dccps_iss = secure_dccpv6_sequence_number(np->saddr.s6_addr32,
  						      np->daddr.s6_addr32,

  						      inet->inet_sport,
  						      inet->inet_dport);

  	err = dccp_connect(sk);
  	if (err)
  		goto late_failure;
  
  	return 0;
  
  late_failure:
  	dccp_set_state(sk, DCCP_CLOSED);
  	__sk_dst_reset(sk);
  failure:

  	inet->inet_dport = 0;

  	sk->sk_route_caps = 0;
  	return err;
  }

  static const struct inet_connection_sock_af_ops dccp_ipv6_af_ops = {

  	.queue_xmit	   = inet6_csk_xmit,
  	.send_check	   = dccp_v6_send_check,
  	.rebuild_header	   = inet6_sk_rebuild_header,
  	.conn_request	   = dccp_v6_conn_request,
  	.syn_recv_sock	   = dccp_v6_request_recv_sock,
  	.net_header_len	   = sizeof(struct ipv6hdr),
  	.setsockopt	   = ipv6_setsockopt,
  	.getsockopt	   = ipv6_getsockopt,
  	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
  	.sockaddr_len	   = sizeof(struct sockaddr_in6),

  	.bind_conflict	   = inet6_csk_bind_conflict,

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_ipv6_setsockopt,
  	.compat_getsockopt = compat_ipv6_getsockopt,

  #endif

  };
  
  /*
   *	DCCP over IPv4 via INET6 API
   */

  static const struct inet_connection_sock_af_ops dccp_ipv6_mapped = {

  	.queue_xmit	   = ip_queue_xmit,
  	.send_check	   = dccp_v4_send_check,
  	.rebuild_header	   = inet_sk_rebuild_header,
  	.conn_request	   = dccp_v6_conn_request,
  	.syn_recv_sock	   = dccp_v6_request_recv_sock,
  	.net_header_len	   = sizeof(struct iphdr),
  	.setsockopt	   = ipv6_setsockopt,
  	.getsockopt	   = ipv6_getsockopt,
  	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
  	.sockaddr_len	   = sizeof(struct sockaddr_in6),

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_ipv6_setsockopt,
  	.compat_getsockopt = compat_ipv6_getsockopt,

  #endif

  };
  
  /* NOTE: A lot of things set to zero explicitly by call to
   *       sk_alloc() so need not be done here.
   */
  static int dccp_v6_init_sock(struct sock *sk)
  {

  	static __u8 dccp_v6_ctl_sock_initialized;
  	int err = dccp_init_sock(sk, dccp_v6_ctl_sock_initialized);

  	if (err == 0) {
  		if (unlikely(!dccp_v6_ctl_sock_initialized))
  			dccp_v6_ctl_sock_initialized = 1;

  		inet_csk(sk)->icsk_af_ops = &dccp_ipv6_af_ops;

  	}

  
  	return err;
  }

  static void dccp_v6_destroy_sock(struct sock *sk)

  {

  	dccp_destroy_sock(sk);

  	inet6_destroy_sock(sk);

  }

  static struct timewait_sock_ops dccp6_timewait_sock_ops = {
  	.twsk_obj_size	= sizeof(struct dccp6_timewait_sock),
  };

  static struct proto dccp_v6_prot = {

  	.name		   = "DCCPv6",
  	.owner		   = THIS_MODULE,
  	.close		   = dccp_close,
  	.connect	   = dccp_v6_connect,
  	.disconnect	   = dccp_disconnect,
  	.ioctl		   = dccp_ioctl,
  	.init		   = dccp_v6_init_sock,
  	.setsockopt	   = dccp_setsockopt,
  	.getsockopt	   = dccp_getsockopt,
  	.sendmsg	   = dccp_sendmsg,
  	.recvmsg	   = dccp_recvmsg,
  	.backlog_rcv	   = dccp_v6_do_rcv,
  	.hash		   = dccp_v6_hash,

  	.unhash		   = inet_unhash,

  	.accept		   = inet_csk_accept,

  	.get_port	   = inet_csk_get_port,

  	.shutdown	   = dccp_shutdown,
  	.destroy	   = dccp_v6_destroy_sock,
  	.orphan_count	   = &dccp_orphan_count,
  	.max_header	   = MAX_DCCP_HEADER,
  	.obj_size	   = sizeof(struct dccp6_sock),

  	.slab_flags	   = SLAB_DESTROY_BY_RCU,

  	.rsk_prot	   = &dccp6_request_sock_ops,
  	.twsk_prot	   = &dccp6_timewait_sock_ops,

  	.h.hashinfo	   = &dccp_hashinfo,

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_dccp_setsockopt,
  	.compat_getsockopt = compat_dccp_getsockopt,

  #endif

  };

  static const struct inet6_protocol dccp_v6_protocol = {

  	.handler	= dccp_v6_rcv,
  	.err_handler	= dccp_v6_err,
  	.flags		= INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,

  };

  static const struct proto_ops inet6_dccp_ops = {

  	.family		   = PF_INET6,
  	.owner		   = THIS_MODULE,
  	.release	   = inet6_release,
  	.bind		   = inet6_bind,
  	.connect	   = inet_stream_connect,
  	.socketpair	   = sock_no_socketpair,
  	.accept		   = inet_accept,
  	.getname	   = inet6_getname,
  	.poll		   = dccp_poll,
  	.ioctl		   = inet6_ioctl,
  	.listen		   = inet_dccp_listen,
  	.shutdown	   = inet_shutdown,
  	.setsockopt	   = sock_common_setsockopt,
  	.getsockopt	   = sock_common_getsockopt,
  	.sendmsg	   = inet_sendmsg,
  	.recvmsg	   = sock_common_recvmsg,
  	.mmap		   = sock_no_mmap,
  	.sendpage	   = sock_no_sendpage,

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_sock_common_setsockopt,
  	.compat_getsockopt = compat_sock_common_getsockopt,

  #endif

  };
  
  static struct inet_protosw dccp_v6_protosw = {
  	.type		= SOCK_DCCP,
  	.protocol	= IPPROTO_DCCP,
  	.prot		= &dccp_v6_prot,
  	.ops		= &inet6_dccp_ops,

  	.flags		= INET_PROTOSW_ICSK,

  };

  static int __net_init dccp_v6_init_net(struct net *net)

  {

  	if (dccp_hashinfo.bhash == NULL)
  		return -ESOCKTNOSUPPORT;

  	return inet_ctl_sock_create(&net->dccp.v6_ctl_sk, PF_INET6,
  				    SOCK_DCCP, IPPROTO_DCCP, net);

  }

  static void __net_exit dccp_v6_exit_net(struct net *net)

  {

  	inet_ctl_sock_destroy(net->dccp.v6_ctl_sk);

  }
  
  static struct pernet_operations dccp_v6_ops = {
  	.init   = dccp_v6_init_net,
  	.exit   = dccp_v6_exit_net,
  };

  static int __init dccp_v6_init(void)
  {
  	int err = proto_register(&dccp_v6_prot, 1);
  
  	if (err != 0)
  		goto out;
  
  	err = inet6_add_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
  	if (err != 0)
  		goto out_unregister_proto;
  
  	inet6_register_protosw(&dccp_v6_protosw);

  	err = register_pernet_subsys(&dccp_v6_ops);
  	if (err != 0)
  		goto out_destroy_ctl_sock;

  out:
  	return err;

  
  out_destroy_ctl_sock:

  	inet6_del_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
  	inet6_unregister_protosw(&dccp_v6_protosw);

  out_unregister_proto:
  	proto_unregister(&dccp_v6_prot);
  	goto out;
  }
  
  static void __exit dccp_v6_exit(void)
  {

  	unregister_pernet_subsys(&dccp_v6_ops);

  	inet6_del_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
  	inet6_unregister_protosw(&dccp_v6_protosw);
  	proto_unregister(&dccp_v6_prot);
  }
  
  module_init(dccp_v6_init);
  module_exit(dccp_v6_exit);
  
  /*
   * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
   * values directly, Also cover the case where the protocol is not specified,
   * i.e. net-pf-PF_INET6-proto-0-type-SOCK_DCCP
   */

  MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 33, 6);
  MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 0, 6);

  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
  MODULE_DESCRIPTION("DCCPv6 - Datagram Congestion Controlled Protocol");