/*
   * DCCP connection tracking protocol helper
   *
   * Copyright (c) 2005, 2006, 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 version 2 as
   * published by the Free Software Foundation.
   *
   */
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/sysctl.h>
  #include <linux/spinlock.h>
  #include <linux/skbuff.h>
  #include <linux/dccp.h>

  #include <linux/slab.h>

  #include <net/net_namespace.h>
  #include <net/netns/generic.h>

  #include <linux/netfilter/nfnetlink_conntrack.h>
  #include <net/netfilter/nf_conntrack.h>
  #include <net/netfilter/nf_conntrack_l4proto.h>

  #include <net/netfilter/nf_conntrack_ecache.h>

  #include <net/netfilter/nf_log.h>

  /* Timeouts are based on values from RFC4340:
   *
   * - REQUEST:
   *
   *   8.1.2. Client Request
   *
   *   A client MAY give up on its DCCP-Requests after some time
   *   (3 minutes, for example).
   *
   * - RESPOND:
   *
   *   8.1.3. Server Response
   *
   *   It MAY also leave the RESPOND state for CLOSED after a timeout of
   *   not less than 4MSL (8 minutes);
   *
   * - PARTOPEN:
   *
   *   8.1.5. Handshake Completion
   *
   *   If the client remains in PARTOPEN for more than 4MSL (8 minutes),
   *   it SHOULD reset the connection with Reset Code 2, "Aborted".
   *
   * - OPEN:
   *
   *   The DCCP timestamp overflows after 11.9 hours. If the connection
   *   stays idle this long the sequence number won't be recognized
   *   as valid anymore.
   *
   * - CLOSEREQ/CLOSING:
   *
   *   8.3. Termination
   *
   *   The retransmission timer should initially be set to go off in two
   *   round-trip times and should back off to not less than once every
   *   64 seconds ...
   *
   * - TIMEWAIT:
   *
   *   4.3. States
   *
   *   A server or client socket remains in this state for 2MSL (4 minutes)
   *   after the connection has been town down, ...
   */
  
  #define DCCP_MSL (2 * 60 * HZ)

  static const char * const dccp_state_names[] = {
  	[CT_DCCP_NONE]		= "NONE",
  	[CT_DCCP_REQUEST]	= "REQUEST",
  	[CT_DCCP_RESPOND]	= "RESPOND",
  	[CT_DCCP_PARTOPEN]	= "PARTOPEN",
  	[CT_DCCP_OPEN]		= "OPEN",
  	[CT_DCCP_CLOSEREQ]	= "CLOSEREQ",
  	[CT_DCCP_CLOSING]	= "CLOSING",
  	[CT_DCCP_TIMEWAIT]	= "TIMEWAIT",
  	[CT_DCCP_IGNORE]	= "IGNORE",
  	[CT_DCCP_INVALID]	= "INVALID",
  };
  
  #define sNO	CT_DCCP_NONE
  #define sRQ	CT_DCCP_REQUEST
  #define sRS	CT_DCCP_RESPOND
  #define sPO	CT_DCCP_PARTOPEN
  #define sOP	CT_DCCP_OPEN
  #define sCR	CT_DCCP_CLOSEREQ
  #define sCG	CT_DCCP_CLOSING
  #define sTW	CT_DCCP_TIMEWAIT
  #define sIG	CT_DCCP_IGNORE
  #define sIV	CT_DCCP_INVALID
  
  /*

   * DCCP state transition table

   *
   * The assumption is the same as for TCP tracking:
   *
   * We are the man in the middle. All the packets go through us but might
   * get lost in transit to the destination. It is assumed that the destination
   * can't receive segments we haven't seen.
   *
   * The following states exist:
   *
   * NONE:	Initial state, expecting Request
   * REQUEST:	Request seen, waiting for Response from server
   * RESPOND:	Response from server seen, waiting for Ack from client
   * PARTOPEN:	Ack after Response seen, waiting for packet other than Response,
   * 		Reset or Sync from server
   * OPEN:	Packet other than Response, Reset or Sync seen
   * CLOSEREQ:	CloseReq from server seen, expecting Close from client
   * CLOSING:	Close seen, expecting Reset
   * TIMEWAIT:	Reset seen
   * IGNORE:	Not determinable whether packet is valid
   *
   * Some states exist only on one side of the connection: REQUEST, RESPOND,
   * PARTOPEN, CLOSEREQ. For the other side these states are equivalent to
   * the one it was in before.
   *
   * Packets are marked as ignored (sIG) if we don't know if they're valid
   * (for example a reincarnation of a connection we didn't notice is dead
   * already) and the server may send back a connection closing Reset or a
   * Response. They're also used for Sync/SyncAck packets, which we don't
   * care about.
   */
  static const u_int8_t
  dccp_state_table[CT_DCCP_ROLE_MAX + 1][DCCP_PKT_SYNCACK + 1][CT_DCCP_MAX + 1] = {
  	[CT_DCCP_ROLE_CLIENT] = {
  		[DCCP_PKT_REQUEST] = {
  		/*
  		 * sNO -> sRQ		Regular Request
  		 * sRQ -> sRQ		Retransmitted Request or reincarnation
  		 * sRS -> sRS		Retransmitted Request (apparently Response
  		 * 			got lost after we saw it) or reincarnation
  		 * sPO -> sIG		Ignore, conntrack might be out of sync
  		 * sOP -> sIG		Ignore, conntrack might be out of sync
  		 * sCR -> sIG		Ignore, conntrack might be out of sync
  		 * sCG -> sIG		Ignore, conntrack might be out of sync
  		 * sTW -> sRQ		Reincarnation
  		 *
  		 *	sNO, sRQ, sRS, sPO. sOP, sCR, sCG, sTW, */
  			sRQ, sRQ, sRS, sIG, sIG, sIG, sIG, sRQ,
  		},
  		[DCCP_PKT_RESPONSE] = {
  		/*
  		 * sNO -> sIV		Invalid
  		 * sRQ -> sIG		Ignore, might be response to ignored Request
  		 * sRS -> sIG		Ignore, might be response to ignored Request
  		 * sPO -> sIG		Ignore, might be response to ignored Request
  		 * sOP -> sIG		Ignore, might be response to ignored Request
  		 * sCR -> sIG		Ignore, might be response to ignored Request
  		 * sCG -> sIG		Ignore, might be response to ignored Request
  		 * sTW -> sIV		Invalid, reincarnation in reverse direction
  		 *			goes through sRQ
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIV,
  		},
  		[DCCP_PKT_ACK] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sPO		Ack for Response, move to PARTOPEN (8.1.5.)
  		 * sPO -> sPO		Retransmitted Ack for Response, remain in PARTOPEN
  		 * sOP -> sOP		Regular ACK, remain in OPEN
  		 * sCR -> sCR		Ack in CLOSEREQ MAY be processed (8.3.)
  		 * sCG -> sCG		Ack in CLOSING MAY be processed (8.3.)
  		 * sTW -> sIV
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
  		},
  		[DCCP_PKT_DATA] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sIV		No connection
  		 * sPO -> sIV		MUST use DataAck in PARTOPEN state (8.1.5.)
  		 * sOP -> sOP		Regular Data packet
  		 * sCR -> sCR		Data in CLOSEREQ MAY be processed (8.3.)
  		 * sCG -> sCG		Data in CLOSING MAY be processed (8.3.)
  		 * sTW -> sIV
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sIV, sIV, sOP, sCR, sCG, sIV,
  		},
  		[DCCP_PKT_DATAACK] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sPO		Ack for Response, move to PARTOPEN (8.1.5.)
  		 * sPO -> sPO		Remain in PARTOPEN state
  		 * sOP -> sOP		Regular DataAck packet in OPEN state
  		 * sCR -> sCR		DataAck in CLOSEREQ MAY be processed (8.3.)
  		 * sCG -> sCG		DataAck in CLOSING MAY be processed (8.3.)
  		 * sTW -> sIV
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
  		},
  		[DCCP_PKT_CLOSEREQ] = {
  		/*
  		 * CLOSEREQ may only be sent by the server.
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV
  		},
  		[DCCP_PKT_CLOSE] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sIV		No connection
  		 * sPO -> sCG		Client-initiated close
  		 * sOP -> sCG		Client-initiated close
  		 * sCR -> sCG		Close in response to CloseReq (8.3.)
  		 * sCG -> sCG		Retransmit
  		 * sTW -> sIV		Late retransmit, already in TIME_WAIT
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sIV, sCG, sCG, sCG, sIV, sIV
  		},
  		[DCCP_PKT_RESET] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sTW		Sync received or timeout, SHOULD send Reset (8.1.1.)
  		 * sRS -> sTW		Response received without Request
  		 * sPO -> sTW		Timeout, SHOULD send Reset (8.1.5.)
  		 * sOP -> sTW		Connection reset
  		 * sCR -> sTW		Connection reset
  		 * sCG -> sTW		Connection reset
  		 * sTW -> sIG		Ignore (don't refresh timer)
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sTW, sTW, sTW, sTW, sTW, sTW, sIG
  		},
  		[DCCP_PKT_SYNC] = {
  		/*
  		 * We currently ignore Sync packets
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
  		},
  		[DCCP_PKT_SYNCACK] = {
  		/*
  		 * We currently ignore SyncAck packets
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
  		},
  	},
  	[CT_DCCP_ROLE_SERVER] = {
  		[DCCP_PKT_REQUEST] = {
  		/*
  		 * sNO -> sIV		Invalid
  		 * sRQ -> sIG		Ignore, conntrack might be out of sync
  		 * sRS -> sIG		Ignore, conntrack might be out of sync
  		 * sPO -> sIG		Ignore, conntrack might be out of sync
  		 * sOP -> sIG		Ignore, conntrack might be out of sync
  		 * sCR -> sIG		Ignore, conntrack might be out of sync
  		 * sCG -> sIG		Ignore, conntrack might be out of sync
  		 * sTW -> sRQ		Reincarnation, must reverse roles
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIG, sIG, sIG, sIG, sIG, sIG, sRQ
  		},
  		[DCCP_PKT_RESPONSE] = {
  		/*
  		 * sNO -> sIV		Response without Request
  		 * sRQ -> sRS		Response to clients Request
  		 * sRS -> sRS		Retransmitted Response (8.1.3. SHOULD NOT)
  		 * sPO -> sIG		Response to an ignored Request or late retransmit
  		 * sOP -> sIG		Ignore, might be response to ignored Request
  		 * sCR -> sIG		Ignore, might be response to ignored Request
  		 * sCG -> sIG		Ignore, might be response to ignored Request
  		 * sTW -> sIV		Invalid, Request from client in sTW moves to sRQ
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sRS, sRS, sIG, sIG, sIG, sIG, sIV
  		},
  		[DCCP_PKT_ACK] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sIV		No connection
  		 * sPO -> sOP		Enter OPEN state (8.1.5.)
  		 * sOP -> sOP		Regular Ack in OPEN state
  		 * sCR -> sIV		Waiting for Close from client
  		 * sCG -> sCG		Ack in CLOSING MAY be processed (8.3.)
  		 * sTW -> sIV
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
  		},
  		[DCCP_PKT_DATA] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sIV		No connection
  		 * sPO -> sOP		Enter OPEN state (8.1.5.)
  		 * sOP -> sOP		Regular Data packet in OPEN state
  		 * sCR -> sIV		Waiting for Close from client
  		 * sCG -> sCG		Data in CLOSING MAY be processed (8.3.)
  		 * sTW -> sIV
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
  		},
  		[DCCP_PKT_DATAACK] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sIV		No connection
  		 * sPO -> sOP		Enter OPEN state (8.1.5.)
  		 * sOP -> sOP		Regular DataAck in OPEN state
  		 * sCR -> sIV		Waiting for Close from client
  		 * sCG -> sCG		Data in CLOSING MAY be processed (8.3.)
  		 * sTW -> sIV
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
  		},
  		[DCCP_PKT_CLOSEREQ] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sIV		No connection
  		 * sPO -> sOP -> sCR	Move directly to CLOSEREQ (8.1.5.)
  		 * sOP -> sCR		CloseReq in OPEN state
  		 * sCR -> sCR		Retransmit
  		 * sCG -> sCR		Simultaneous close, client sends another Close
  		 * sTW -> sIV		Already closed
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sIV, sCR, sCR, sCR, sCR, sIV
  		},
  		[DCCP_PKT_CLOSE] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sIV		No connection
  		 * sRS -> sIV		No connection
  		 * sPO -> sOP -> sCG	Move direcly to CLOSING
  		 * sOP -> sCG		Move to CLOSING
  		 * sCR -> sIV		Close after CloseReq is invalid
  		 * sCG -> sCG		Retransmit
  		 * sTW -> sIV		Already closed
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIV, sIV, sIV, sCG, sCG, sIV, sCG, sIV
  		},
  		[DCCP_PKT_RESET] = {
  		/*
  		 * sNO -> sIV		No connection
  		 * sRQ -> sTW		Reset in response to Request
  		 * sRS -> sTW		Timeout, SHOULD send Reset (8.1.3.)
  		 * sPO -> sTW		Timeout, SHOULD send Reset (8.1.3.)
  		 * sOP -> sTW
  		 * sCR -> sTW
  		 * sCG -> sTW
  		 * sTW -> sIG		Ignore (don't refresh timer)
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW, sTW */
  			sIV, sTW, sTW, sTW, sTW, sTW, sTW, sTW, sIG
  		},
  		[DCCP_PKT_SYNC] = {
  		/*
  		 * We currently ignore Sync packets
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
  		},
  		[DCCP_PKT_SYNCACK] = {
  		/*
  		 * We currently ignore SyncAck packets
  		 *
  		 *	sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
  			sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
  		},
  	},
  };

  /* this module per-net specifics */

  static int dccp_net_id __read_mostly;

  struct dccp_net {
  	int dccp_loose;
  	unsigned int dccp_timeout[CT_DCCP_MAX + 1];
  #ifdef CONFIG_SYSCTL
  	struct ctl_table_header *sysctl_header;
  	struct ctl_table *sysctl_table;
  #endif
  };
  
  static inline struct dccp_net *dccp_pernet(struct net *net)
  {
  	return net_generic(net, dccp_net_id);
  }

  static bool dccp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
  			      struct nf_conntrack_tuple *tuple)

  {
  	struct dccp_hdr _hdr, *dh;
  
  	dh = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  	if (dh == NULL)

  		return false;

  
  	tuple->src.u.dccp.port = dh->dccph_sport;
  	tuple->dst.u.dccp.port = dh->dccph_dport;

  	return true;

  }

  static bool dccp_invert_tuple(struct nf_conntrack_tuple *inv,
  			      const struct nf_conntrack_tuple *tuple)

  {
  	inv->src.u.dccp.port = tuple->dst.u.dccp.port;
  	inv->dst.u.dccp.port = tuple->src.u.dccp.port;

  	return true;

  }

  static bool dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
  		     unsigned int dataoff)

  {

  	struct net *net = nf_ct_net(ct);

  	struct dccp_net *dn;

  	struct dccp_hdr _dh, *dh;
  	const char *msg;
  	u_int8_t state;
  
  	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
  	BUG_ON(dh == NULL);
  
  	state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
  	switch (state) {
  	default:

  		dn = dccp_pernet(net);
  		if (dn->dccp_loose == 0) {

  			msg = "nf_ct_dccp: not picking up existing connection ";
  			goto out_invalid;
  		}
  	case CT_DCCP_REQUEST:
  		break;
  	case CT_DCCP_INVALID:
  		msg = "nf_ct_dccp: invalid state transition ";
  		goto out_invalid;
  	}
  
  	ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
  	ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
  	ct->proto.dccp.state = CT_DCCP_NONE;

  	ct->proto.dccp.last_pkt = DCCP_PKT_REQUEST;
  	ct->proto.dccp.last_dir = IP_CT_DIR_ORIGINAL;
  	ct->proto.dccp.handshake_seq = 0;

  	return true;

  
  out_invalid:

  	if (LOG_INVALID(net, IPPROTO_DCCP))

  		nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL, msg);

  	return false;

  }
  
  static u64 dccp_ack_seq(const struct dccp_hdr *dh)
  {
  	const struct dccp_hdr_ack_bits *dhack;
  
  	dhack = (void *)dh + __dccp_basic_hdr_len(dh);
  	return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
  		     ntohl(dhack->dccph_ack_nr_low);
  }
  
  static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
  		       unsigned int dataoff, enum ip_conntrack_info ctinfo,

  		       u_int8_t pf, unsigned int hooknum)

  {

  	struct net *net = nf_ct_net(ct);

  	struct dccp_net *dn;

  	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
  	struct dccp_hdr _dh, *dh;
  	u_int8_t type, old_state, new_state;
  	enum ct_dccp_roles role;
  
  	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
  	BUG_ON(dh == NULL);
  	type = dh->dccph_type;
  
  	if (type == DCCP_PKT_RESET &&
  	    !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  		/* Tear down connection immediately if only reply is a RESET */

  		nf_ct_kill_acct(ct, ctinfo, skb);

  		return NF_ACCEPT;
  	}

  	spin_lock_bh(&ct->lock);

  
  	role = ct->proto.dccp.role[dir];
  	old_state = ct->proto.dccp.state;
  	new_state = dccp_state_table[role][type][old_state];
  
  	switch (new_state) {
  	case CT_DCCP_REQUEST:
  		if (old_state == CT_DCCP_TIMEWAIT &&
  		    role == CT_DCCP_ROLE_SERVER) {
  			/* Reincarnation in the reverse direction: reopen and
  			 * reverse client/server roles. */
  			ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
  			ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
  		}
  		break;
  	case CT_DCCP_RESPOND:
  		if (old_state == CT_DCCP_REQUEST)
  			ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
  		break;
  	case CT_DCCP_PARTOPEN:
  		if (old_state == CT_DCCP_RESPOND &&
  		    type == DCCP_PKT_ACK &&
  		    dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
  			set_bit(IPS_ASSURED_BIT, &ct->status);
  		break;
  	case CT_DCCP_IGNORE:
  		/*
  		 * Connection tracking might be out of sync, so we ignore
  		 * packets that might establish a new connection and resync
  		 * if the server responds with a valid Response.
  		 */
  		if (ct->proto.dccp.last_dir == !dir &&
  		    ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
  		    type == DCCP_PKT_RESPONSE) {
  			ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
  			ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
  			ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
  			new_state = CT_DCCP_RESPOND;
  			break;
  		}
  		ct->proto.dccp.last_dir = dir;
  		ct->proto.dccp.last_pkt = type;

  		spin_unlock_bh(&ct->lock);

  		if (LOG_INVALID(net, IPPROTO_DCCP))

  			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
  				      "nf_ct_dccp: invalid packet ignored ");
  		return NF_ACCEPT;
  	case CT_DCCP_INVALID:

  		spin_unlock_bh(&ct->lock);

  		if (LOG_INVALID(net, IPPROTO_DCCP))

  			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
  				      "nf_ct_dccp: invalid state transition ");
  		return -NF_ACCEPT;
  	}
  
  	ct->proto.dccp.last_dir = dir;
  	ct->proto.dccp.last_pkt = type;
  	ct->proto.dccp.state = new_state;

  	spin_unlock_bh(&ct->lock);

  	if (new_state != old_state)
  		nf_conntrack_event_cache(IPCT_PROTOINFO, ct);

  	dn = dccp_pernet(net);
  	nf_ct_refresh_acct(ct, ctinfo, skb, dn->dccp_timeout[new_state]);

  
  	return NF_ACCEPT;
  }

  static int dccp_error(struct net *net, struct nf_conn *tmpl,
  		      struct sk_buff *skb, unsigned int dataoff,
  		      enum ip_conntrack_info *ctinfo,

  		      u_int8_t pf, unsigned int hooknum)

  {
  	struct dccp_hdr _dh, *dh;
  	unsigned int dccp_len = skb->len - dataoff;
  	unsigned int cscov;
  	const char *msg;
  
  	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
  	if (dh == NULL) {
  		msg = "nf_ct_dccp: short packet ";
  		goto out_invalid;
  	}
  
  	if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
  	    dh->dccph_doff * 4 > dccp_len) {
  		msg = "nf_ct_dccp: truncated/malformed packet ";
  		goto out_invalid;
  	}
  
  	cscov = dccp_len;
  	if (dh->dccph_cscov) {
  		cscov = (dh->dccph_cscov - 1) * 4;
  		if (cscov > dccp_len) {
  			msg = "nf_ct_dccp: bad checksum coverage ";
  			goto out_invalid;
  		}
  	}

  	if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&

  	    nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_DCCP,
  				pf)) {
  		msg = "nf_ct_dccp: bad checksum ";
  		goto out_invalid;
  	}
  
  	if (dh->dccph_type >= DCCP_PKT_INVALID) {
  		msg = "nf_ct_dccp: reserved packet type ";
  		goto out_invalid;
  	}
  
  	return NF_ACCEPT;
  
  out_invalid:

  	if (LOG_INVALID(net, IPPROTO_DCCP))

  		nf_log_packet(pf, 0, skb, NULL, NULL, NULL, msg);
  	return -NF_ACCEPT;
  }
  
  static int dccp_print_tuple(struct seq_file *s,
  			    const struct nf_conntrack_tuple *tuple)
  {
  	return seq_printf(s, "sport=%hu dport=%hu ",
  			  ntohs(tuple->src.u.dccp.port),
  			  ntohs(tuple->dst.u.dccp.port));
  }

  static int dccp_print_conntrack(struct seq_file *s, struct nf_conn *ct)

  {
  	return seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
  }

  #if IS_ENABLED(CONFIG_NF_CT_NETLINK)

  static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,

  			  struct nf_conn *ct)

  {
  	struct nlattr *nest_parms;

  	spin_lock_bh(&ct->lock);

  	nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP | NLA_F_NESTED);
  	if (!nest_parms)
  		goto nla_put_failure;
  	NLA_PUT_U8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state);

  	NLA_PUT_U8(skb, CTA_PROTOINFO_DCCP_ROLE,
  		   ct->proto.dccp.role[IP_CT_DIR_ORIGINAL]);

  	NLA_PUT_BE64(skb, CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ,
  		     cpu_to_be64(ct->proto.dccp.handshake_seq));

  	nla_nest_end(skb, nest_parms);

  	spin_unlock_bh(&ct->lock);

  	return 0;
  
  nla_put_failure:

  	spin_unlock_bh(&ct->lock);

  	return -1;
  }
  
  static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
  	[CTA_PROTOINFO_DCCP_STATE]	= { .type = NLA_U8 },

  	[CTA_PROTOINFO_DCCP_ROLE]	= { .type = NLA_U8 },

  	[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ] = { .type = NLA_U64 },

  };
  
  static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
  {
  	struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
  	struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
  	int err;
  
  	if (!attr)
  		return 0;
  
  	err = nla_parse_nested(tb, CTA_PROTOINFO_DCCP_MAX, attr,
  			       dccp_nla_policy);
  	if (err < 0)
  		return err;
  
  	if (!tb[CTA_PROTOINFO_DCCP_STATE] ||

  	    !tb[CTA_PROTOINFO_DCCP_ROLE] ||
  	    nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) > CT_DCCP_ROLE_MAX ||
  	    nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE) {

  		return -EINVAL;

  	}

  	spin_lock_bh(&ct->lock);

  	ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);

  	if (nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) == CT_DCCP_ROLE_CLIENT) {
  		ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
  		ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
  	} else {
  		ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_SERVER;
  		ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_CLIENT;
  	}

  	if (tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]) {
  		ct->proto.dccp.handshake_seq =
  		be64_to_cpu(nla_get_be64(tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]));
  	}

  	spin_unlock_bh(&ct->lock);

  	return 0;
  }

  
  static int dccp_nlattr_size(void)
  {
  	return nla_total_size(0)	/* CTA_PROTOINFO_DCCP */
  		+ nla_policy_len(dccp_nla_policy, CTA_PROTOINFO_DCCP_MAX + 1);
  }

  #endif
  
  #ifdef CONFIG_SYSCTL

  /* template, data assigned later */
  static struct ctl_table dccp_sysctl_table[] = {

  	{

  		.procname	= "nf_conntrack_dccp_timeout_request",

  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_jiffies,
  	},
  	{

  		.procname	= "nf_conntrack_dccp_timeout_respond",

  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_jiffies,
  	},
  	{

  		.procname	= "nf_conntrack_dccp_timeout_partopen",

  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_jiffies,
  	},
  	{

  		.procname	= "nf_conntrack_dccp_timeout_open",

  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_jiffies,
  	},
  	{

  		.procname	= "nf_conntrack_dccp_timeout_closereq",

  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_jiffies,
  	},
  	{

  		.procname	= "nf_conntrack_dccp_timeout_closing",

  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_jiffies,
  	},
  	{

  		.procname	= "nf_conntrack_dccp_timeout_timewait",

  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_jiffies,
  	},
  	{

  		.procname	= "nf_conntrack_dccp_loose",

  		.maxlen		= sizeof(int),

  		.mode		= 0644,
  		.proc_handler	= proc_dointvec,
  	},

  	{ }

  };
  #endif /* CONFIG_SYSCTL */
  
  static struct nf_conntrack_l4proto dccp_proto4 __read_mostly = {
  	.l3proto		= AF_INET,
  	.l4proto		= IPPROTO_DCCP,
  	.name			= "dccp",
  	.pkt_to_tuple		= dccp_pkt_to_tuple,
  	.invert_tuple		= dccp_invert_tuple,
  	.new			= dccp_new,
  	.packet			= dccp_packet,
  	.error			= dccp_error,
  	.print_tuple		= dccp_print_tuple,
  	.print_conntrack	= dccp_print_conntrack,

  #if IS_ENABLED(CONFIG_NF_CT_NETLINK)

  	.to_nlattr		= dccp_to_nlattr,

  	.nlattr_size		= dccp_nlattr_size,

  	.from_nlattr		= nlattr_to_dccp,
  	.tuple_to_nlattr	= nf_ct_port_tuple_to_nlattr,

  	.nlattr_tuple_size	= nf_ct_port_nlattr_tuple_size,

  	.nlattr_to_tuple	= nf_ct_port_nlattr_to_tuple,
  	.nla_policy		= nf_ct_port_nla_policy,
  #endif

  };
  
  static struct nf_conntrack_l4proto dccp_proto6 __read_mostly = {
  	.l3proto		= AF_INET6,
  	.l4proto		= IPPROTO_DCCP,
  	.name			= "dccp",
  	.pkt_to_tuple		= dccp_pkt_to_tuple,
  	.invert_tuple		= dccp_invert_tuple,
  	.new			= dccp_new,
  	.packet			= dccp_packet,
  	.error			= dccp_error,
  	.print_tuple		= dccp_print_tuple,
  	.print_conntrack	= dccp_print_conntrack,

  #if IS_ENABLED(CONFIG_NF_CT_NETLINK)

  	.to_nlattr		= dccp_to_nlattr,

  	.nlattr_size		= dccp_nlattr_size,

  	.from_nlattr		= nlattr_to_dccp,
  	.tuple_to_nlattr	= nf_ct_port_tuple_to_nlattr,

  	.nlattr_tuple_size	= nf_ct_port_nlattr_tuple_size,

  	.nlattr_to_tuple	= nf_ct_port_nlattr_to_tuple,
  	.nla_policy		= nf_ct_port_nla_policy,
  #endif

  };
  
  static __net_init int dccp_net_init(struct net *net)
  {

  	struct dccp_net *dn = dccp_pernet(net);

  
  	/* default values */
  	dn->dccp_loose = 1;
  	dn->dccp_timeout[CT_DCCP_REQUEST]	= 2 * DCCP_MSL;
  	dn->dccp_timeout[CT_DCCP_RESPOND]	= 4 * DCCP_MSL;
  	dn->dccp_timeout[CT_DCCP_PARTOPEN]	= 4 * DCCP_MSL;
  	dn->dccp_timeout[CT_DCCP_OPEN]		= 12 * 3600 * HZ;
  	dn->dccp_timeout[CT_DCCP_CLOSEREQ]	= 64 * HZ;
  	dn->dccp_timeout[CT_DCCP_CLOSING]	= 64 * HZ;
  	dn->dccp_timeout[CT_DCCP_TIMEWAIT]	= 2 * DCCP_MSL;

  #ifdef CONFIG_SYSCTL

  	dn->sysctl_table = kmemdup(dccp_sysctl_table,
  			sizeof(dccp_sysctl_table), GFP_KERNEL);
  	if (!dn->sysctl_table)

  		return -ENOMEM;

  
  	dn->sysctl_table[0].data = &dn->dccp_timeout[CT_DCCP_REQUEST];
  	dn->sysctl_table[1].data = &dn->dccp_timeout[CT_DCCP_RESPOND];
  	dn->sysctl_table[2].data = &dn->dccp_timeout[CT_DCCP_PARTOPEN];
  	dn->sysctl_table[3].data = &dn->dccp_timeout[CT_DCCP_OPEN];
  	dn->sysctl_table[4].data = &dn->dccp_timeout[CT_DCCP_CLOSEREQ];
  	dn->sysctl_table[5].data = &dn->dccp_timeout[CT_DCCP_CLOSING];
  	dn->sysctl_table[6].data = &dn->dccp_timeout[CT_DCCP_TIMEWAIT];
  	dn->sysctl_table[7].data = &dn->dccp_loose;
  
  	dn->sysctl_header = register_net_sysctl_table(net,
  			nf_net_netfilter_sysctl_path, dn->sysctl_table);
  	if (!dn->sysctl_header) {
  		kfree(dn->sysctl_table);

  		return -ENOMEM;

  	}

  #endif

  
  	return 0;

  }
  
  static __net_exit void dccp_net_exit(struct net *net)
  {
  	struct dccp_net *dn = dccp_pernet(net);
  #ifdef CONFIG_SYSCTL
  	unregister_net_sysctl_table(dn->sysctl_header);
  	kfree(dn->sysctl_table);
  #endif

  }
  
  static struct pernet_operations dccp_net_ops = {
  	.init = dccp_net_init,
  	.exit = dccp_net_exit,

  	.id   = &dccp_net_id,
  	.size = sizeof(struct dccp_net),

  };
  
  static int __init nf_conntrack_proto_dccp_init(void)
  {
  	int err;

  	err = register_pernet_subsys(&dccp_net_ops);

  	if (err < 0)
  		goto err1;

  	err = nf_conntrack_l4proto_register(&dccp_proto4);

  	if (err < 0)
  		goto err2;

  
  	err = nf_conntrack_l4proto_register(&dccp_proto6);
  	if (err < 0)
  		goto err3;

  	return 0;

  err3:

  	nf_conntrack_l4proto_unregister(&dccp_proto4);

  err2:

  	unregister_pernet_subsys(&dccp_net_ops);

  err1:
  	return err;
  }
  
  static void __exit nf_conntrack_proto_dccp_fini(void)
  {

  	unregister_pernet_subsys(&dccp_net_ops);

  	nf_conntrack_l4proto_unregister(&dccp_proto6);
  	nf_conntrack_l4proto_unregister(&dccp_proto4);
  }
  
  module_init(nf_conntrack_proto_dccp_init);
  module_exit(nf_conntrack_proto_dccp_fini);
  
  MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  MODULE_DESCRIPTION("DCCP connection tracking protocol helper");
  MODULE_LICENSE("GPL");