/* SPDX-License-Identifier: GPL-2.0-only */

  #ifndef _DCCP_H
  #define _DCCP_H
  /*
   *  net/dccp/dccp.h
   *
   *  An implementation of the DCCP protocol

   *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>

   *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>

   */
  
  #include <linux/dccp.h>

  #include <linux/ktime.h>

  #include <net/snmp.h>
  #include <net/sock.h>
  #include <net/tcp.h>

  #include "ackvec.h"

  /*
   * 	DCCP - specific warning and debugging macros.
   */

  #define DCCP_WARN(fmt, ...)						\
  	net_warn_ratelimited("%s: " fmt, __func__, ##__VA_ARGS__)

  #define DCCP_CRIT(fmt, a...) printk(KERN_CRIT fmt " at %s:%d/%s()
  ", ##a, \

  					 __FILE__, __LINE__, __func__)

  #define DCCP_BUG(a...)       do { DCCP_CRIT("BUG: " a); dump_stack(); } while(0)
  #define DCCP_BUG_ON(cond)    do { if (unlikely((cond) != 0))		   \
  				     DCCP_BUG("\"%s\" holds (exception!)", \
  					      __stringify(cond));          \

  			     } while (0)

  #define DCCP_PRINTK(enable, fmt, args...)	do { if (enable)	     \
  							printk(fmt, ##args); \

  						} while(0)

  #define DCCP_PR_DEBUG(enable, fmt, a...)	DCCP_PRINTK(enable, KERN_DEBUG \

  						  "%s: " fmt, __func__, ##a)

  #ifdef CONFIG_IP_DCCP_DEBUG

  extern bool dccp_debug;

  #define dccp_pr_debug(format, a...)	  DCCP_PR_DEBUG(dccp_debug, format, ##a)
  #define dccp_pr_debug_cat(format, a...)   DCCP_PRINTK(dccp_debug, format, ##a)

  #define dccp_debug(fmt, a...)		  dccp_pr_debug_cat(KERN_DEBUG fmt, ##a)

  #else
  #define dccp_pr_debug(format, a...)
  #define dccp_pr_debug_cat(format, a...)

  #define dccp_debug(format, a...)

  #endif
  
  extern struct inet_hashinfo dccp_hashinfo;

  extern struct percpu_counter dccp_orphan_count;

  void dccp_time_wait(struct sock *sk, int state, int timeo);

  /*
   *  Set safe upper bounds for header and option length. Since Data Offset is 8
   *  bits (RFC 4340, sec. 5.1), the total header length can never be more than
   *  4 * 255 = 1020 bytes. The largest possible header length is 28 bytes (X=1):
   *    - DCCP-Response with ACK Subheader and 4 bytes of Service code      OR
   *    - DCCP-Reset    with ACK Subheader and 4 bytes of Reset Code fields
   *  Hence a safe upper bound for the maximum option length is 1020-28 = 992
   */

  #define MAX_DCCP_SPECIFIC_HEADER (255 * sizeof(uint32_t))

  #define DCCP_MAX_PACKET_HDR 28
  #define DCCP_MAX_OPT_LEN (MAX_DCCP_SPECIFIC_HEADER - DCCP_MAX_PACKET_HDR)
  #define MAX_DCCP_HEADER (MAX_DCCP_SPECIFIC_HEADER + MAX_HEADER)

  /* Upper bound for initial feature-negotiation overhead (padded to 32 bits) */
  #define DCCP_FEATNEG_OVERHEAD	 (32 * sizeof(uint32_t))

  #define DCCP_TIMEWAIT_LEN (60 * HZ) /* how long to wait to destroy TIME-WAIT
  				     * state, about 60 seconds */

  /* RFC 1122, 4.2.3.1 initial RTO value */

  #define DCCP_TIMEOUT_INIT ((unsigned int)(3 * HZ))

  /*
   * The maximum back-off value for retransmissions. This is needed for
   *  - retransmitting client-Requests (sec. 8.1.1),
   *  - retransmitting Close/CloseReq when closing (sec. 8.3),
   *  - feature-negotiation retransmission (sec. 6.6.3),
   *  - Acks in client-PARTOPEN state (sec. 8.1.5).
   */

  #define DCCP_RTO_MAX ((unsigned int)(64 * HZ))

  /*
   * RTT sampling: sanity bounds and fallback RTT value from RFC 4340, section 3.4
   */

  #define DCCP_SANE_RTT_MIN	100

  #define DCCP_FALLBACK_RTT	(USEC_PER_SEC / 5)
  #define DCCP_SANE_RTT_MAX	(3 * USEC_PER_SEC)

  /* sysctl variables for DCCP */
  extern int  sysctl_dccp_request_retries;
  extern int  sysctl_dccp_retries1;
  extern int  sysctl_dccp_retries2;

  extern int  sysctl_dccp_tx_qlen;

  extern int  sysctl_dccp_sync_ratelimit;

  /*
   *	48-bit sequence number arithmetic (signed and unsigned)
   */
  #define INT48_MIN	  0x800000000000LL		/* 2^47	    */
  #define UINT48_MAX	  0xFFFFFFFFFFFFLL		/* 2^48 - 1 */
  #define COMPLEMENT48(x)	 (0x1000000000000LL - (x))	/* 2^48 - x */
  #define TO_SIGNED48(x)	 (((x) < INT48_MIN)? (x) : -COMPLEMENT48( (x)))
  #define TO_UNSIGNED48(x) (((x) >= 0)?	     (x) :  COMPLEMENT48(-(x)))
  #define ADD48(a, b)	 (((a) + (b)) & UINT48_MAX)
  #define SUB48(a, b)	 ADD48((a), COMPLEMENT48(b))
  
  static inline void dccp_set_seqno(u64 *seqno, u64 value)
  {
  	*seqno = value & UINT48_MAX;
  }
  
  static inline void dccp_inc_seqno(u64 *seqno)
  {
  	*seqno = ADD48(*seqno, 1);
  }

  /* signed mod-2^48 distance: pos. if seqno1 < seqno2, neg. if seqno1 > seqno2 */
  static inline s64 dccp_delta_seqno(const u64 seqno1, const u64 seqno2)

  {

  	u64 delta = SUB48(seqno2, seqno1);
  
  	return TO_SIGNED48(delta);

  }

  /* is seq1 < seq2 ? */

  static inline int before48(const u64 seq1, const u64 seq2)

  {

  	return (s64)((seq2 << 16) - (seq1 << 16)) > 0;

  }
  
  /* is seq1 > seq2 ? */

  #define after48(seq1, seq2)	before48(seq2, seq1)

  
  /* is seq2 <= seq1 <= seq3 ? */

  static inline int between48(const u64 seq1, const u64 seq2, const u64 seq3)

  {
  	return (seq3 << 16) - (seq2 << 16) >= (seq1 << 16) - (seq2 << 16);
  }
  
  static inline u64 max48(const u64 seq1, const u64 seq2)
  {
  	return after48(seq1, seq2) ? seq1 : seq2;
  }

  /**

   * dccp_loss_count - Approximate the number of lost data packets in a burst loss
   * @s1:  last known sequence number before the loss ('hole')
   * @s2:  first sequence number seen after the 'hole'

   * @ndp: NDP count on packet with sequence number @s2

   */

  static inline u64 dccp_loss_count(const u64 s1, const u64 s2, const u64 ndp)

  {
  	s64 delta = dccp_delta_seqno(s1, s2);

  	WARN_ON(delta < 0);

  	delta -= ndp + 1;
  
  	return delta > 0 ? delta : 0;
  }
  
  /**
   * dccp_loss_free - Evaluate condition for data loss from RFC 4340, 7.7.1
   */
  static inline bool dccp_loss_free(const u64 s1, const u64 s2, const u64 ndp)
  {
  	return dccp_loss_count(s1, s2, ndp) == 0;

  }

  enum {
  	DCCP_MIB_NUM = 0,
  	DCCP_MIB_ACTIVEOPENS,			/* ActiveOpens */
  	DCCP_MIB_ESTABRESETS,			/* EstabResets */
  	DCCP_MIB_CURRESTAB,			/* CurrEstab */

  	DCCP_MIB_OUTSEGS,			/* OutSegs */

  	DCCP_MIB_OUTRSTS,
  	DCCP_MIB_ABORTONTIMEOUT,
  	DCCP_MIB_TIMEOUTS,
  	DCCP_MIB_ABORTFAILED,
  	DCCP_MIB_PASSIVEOPENS,
  	DCCP_MIB_ATTEMPTFAILS,
  	DCCP_MIB_OUTDATAGRAMS,
  	DCCP_MIB_INERRS,
  	DCCP_MIB_OPTMANDATORYERROR,
  	DCCP_MIB_INVALIDOPT,
  	__DCCP_MIB_MAX
  };
  
  #define DCCP_MIB_MAX	__DCCP_MIB_MAX
  struct dccp_mib {
  	unsigned long	mibs[DCCP_MIB_MAX];

  };

  
  DECLARE_SNMP_STAT(struct dccp_mib, dccp_statistics);

  #define DCCP_INC_STATS(field)	SNMP_INC_STATS(dccp_statistics, field)

  #define __DCCP_INC_STATS(field)	__SNMP_INC_STATS(dccp_statistics, field)

  #define DCCP_DEC_STATS(field)	SNMP_DEC_STATS(dccp_statistics, field)

  /*
   * 	Checksumming routines
   */

  static inline unsigned int dccp_csum_coverage(const struct sk_buff *skb)

  {
  	const struct dccp_hdr* dh = dccp_hdr(skb);
  
  	if (dh->dccph_cscov == 0)
  		return skb->len;
  	return (dh->dccph_doff + dh->dccph_cscov - 1) * sizeof(u32);
  }
  
  static inline void dccp_csum_outgoing(struct sk_buff *skb)
  {

  	unsigned int cov = dccp_csum_coverage(skb);

  
  	if (cov >= skb->len)
  		dccp_hdr(skb)->dccph_cscov = 0;
  
  	skb->csum = skb_checksum(skb, 0, (cov > skb->len)? skb->len : cov, 0);
  }

  void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb);

  int dccp_retransmit_skb(struct sock *sk);

  void dccp_send_ack(struct sock *sk);

  void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,

  			 struct request_sock *rsk);

  void dccp_send_sync(struct sock *sk, const u64 seq,
  		    const enum dccp_pkt_type pkt_type);

  /*
   * TX Packet Dequeueing Interface
   */

  void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb);
  bool dccp_qpolicy_full(struct sock *sk);
  void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
  struct sk_buff *dccp_qpolicy_top(struct sock *sk);
  struct sk_buff *dccp_qpolicy_pop(struct sock *sk);
  bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param);

  
  /*
   * TX Packet Output and TX Timers
   */

  void dccp_write_xmit(struct sock *sk);
  void dccp_write_space(struct sock *sk);
  void dccp_flush_write_queue(struct sock *sk, long *time_budget);

  void dccp_init_xmit_timers(struct sock *sk);

  static inline void dccp_clear_xmit_timers(struct sock *sk)
  {
  	inet_csk_clear_xmit_timers(sk);
  }

  unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu);

  const char *dccp_packet_name(const int type);

  void dccp_set_state(struct sock *sk, const int state);
  void dccp_done(struct sock *sk);

  int dccp_reqsk_init(struct request_sock *rq, struct dccp_sock const *dp,
  		    struct sk_buff const *skb);

  int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb);

  struct sock *dccp_create_openreq_child(const struct sock *sk,

  				       const struct request_sock *req,
  				       const struct sk_buff *skb);

  int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);

  struct sock *dccp_v4_request_recv_sock(const struct sock *sk, struct sk_buff *skb,

  				       struct request_sock *req,

  				       struct dst_entry *dst,
  				       struct request_sock *req_unhash,
  				       bool *own_req);

  struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,

  			    struct request_sock *req);

  int dccp_child_process(struct sock *parent, struct sock *child,
  		       struct sk_buff *skb);
  int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
  			   struct dccp_hdr *dh, unsigned int len);
  int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
  			 const struct dccp_hdr *dh, const unsigned int len);

  int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
  void dccp_destroy_sock(struct sock *sk);

  void dccp_close(struct sock *sk, long timeout);

  struct sk_buff *dccp_make_response(const struct sock *sk, struct dst_entry *dst,

  				   struct request_sock *req);

  int dccp_connect(struct sock *sk);
  int dccp_disconnect(struct sock *sk, int flags);
  int dccp_getsockopt(struct sock *sk, int level, int optname,
  		    char __user *optval, int __user *optlen);
  int dccp_setsockopt(struct sock *sk, int level, int optname,
  		    char __user *optval, unsigned int optlen);

  #ifdef CONFIG_COMPAT

  int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
  			   char __user *optval, int __user *optlen);
  int compat_dccp_setsockopt(struct sock *sk, int level, int optname,
  			   char __user *optval, unsigned int optlen);

  #endif

  int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);

  int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
  int dccp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
  		 int flags, int *addr_len);

  void dccp_shutdown(struct sock *sk, int how);
  int inet_dccp_listen(struct socket *sock, int backlog);

  __poll_t dccp_poll(struct file *file, struct socket *sock,
  		       poll_table *wait);

  int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);

  void dccp_req_err(struct sock *sk, u64 seq);

  
  struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *skb);
  int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
  void dccp_send_close(struct sock *sk, const int active);
  int dccp_invalid_packet(struct sk_buff *skb);
  u32 dccp_sample_rtt(struct sock *sk, long delta);

  static inline bool dccp_bad_service_code(const struct sock *sk,

  					const __be32 service)

  {
  	const struct dccp_sock *dp = dccp_sk(sk);
  
  	if (dp->dccps_service == service)

  		return false;

  	return !dccp_list_has_service(dp->dccps_service_list, service);
  }

  /**
   * dccp_skb_cb  -  DCCP per-packet control information
   * @dccpd_type: one of %dccp_pkt_type (or unknown)
   * @dccpd_ccval: CCVal field (5.1), see e.g. RFC 4342, 8.1
   * @dccpd_reset_code: one of %dccp_reset_codes
   * @dccpd_reset_data: Data1..3 fields (depend on @dccpd_reset_code)
   * @dccpd_opt_len: total length of all options (5.8) in the packet
   * @dccpd_seq: sequence number
   * @dccpd_ack_seq: acknowledgment number subheader field value

   *

   * This is used for transmission as well as for reception.
   */

  struct dccp_skb_cb {

  	union {
  		struct inet_skb_parm	h4;

  #if IS_ENABLED(CONFIG_IPV6)

  		struct inet6_skb_parm	h6;
  #endif
  	} header;

  	__u8  dccpd_type:4;
  	__u8  dccpd_ccval:4;

  	__u8  dccpd_reset_code,
  	      dccpd_reset_data[3];

  	__u16 dccpd_opt_len;

  	__u64 dccpd_seq;
  	__u64 dccpd_ack_seq;

  };
  
  #define DCCP_SKB_CB(__skb) ((struct dccp_skb_cb *)&((__skb)->cb[0]))

  /* RFC 4340, sec. 7.7 */

  static inline int dccp_non_data_packet(const struct sk_buff *skb)
  {
  	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
  
  	return type == DCCP_PKT_ACK	 ||
  	       type == DCCP_PKT_CLOSE	 ||
  	       type == DCCP_PKT_CLOSEREQ ||
  	       type == DCCP_PKT_RESET	 ||
  	       type == DCCP_PKT_SYNC	 ||
  	       type == DCCP_PKT_SYNCACK;
  }

  /* RFC 4340, sec. 7.7 */
  static inline int dccp_data_packet(const struct sk_buff *skb)
  {
  	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
  
  	return type == DCCP_PKT_DATA	 ||
  	       type == DCCP_PKT_DATAACK  ||
  	       type == DCCP_PKT_REQUEST  ||
  	       type == DCCP_PKT_RESPONSE;
  }

  static inline int dccp_packet_without_ack(const struct sk_buff *skb)
  {
  	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
  
  	return type == DCCP_PKT_DATA || type == DCCP_PKT_REQUEST;
  }

  #define DCCP_PKT_WITHOUT_ACK_SEQ (UINT48_MAX << 2)

  
  static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss)
  {

  	struct dccp_hdr_ext *dhx = (struct dccp_hdr_ext *)((void *)dh +
  							   sizeof(*dh));

  	dh->dccph_seq2 = 0;
  	dh->dccph_seq = htons((gss >> 32) & 0xfffff);

  	dhx->dccph_seq_low = htonl(gss & 0xffffffff);
  }

  static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
  				    const u64 gsr)

  {

  	dhack->dccph_reserved1 = 0;
  	dhack->dccph_ack_nr_high = htons(gsr >> 32);

  	dhack->dccph_ack_nr_low  = htonl(gsr & 0xffffffff);
  }
  
  static inline void dccp_update_gsr(struct sock *sk, u64 seq)
  {
  	struct dccp_sock *dp = dccp_sk(sk);

  	if (after48(seq, dp->dccps_gsr))
  		dp->dccps_gsr = seq;

  	/* Sequence validity window depends on remote Sequence Window (7.5.1) */
  	dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);

  	/*
  	 * Adjust SWL so that it is not below ISR. In contrast to RFC 4340,
  	 * 7.5.1 we perform this check beyond the initial handshake: W/W' are
  	 * always > 32, so for the first W/W' packets in the lifetime of a
  	 * connection we always have to adjust SWL.
  	 * A second reason why we are doing this is that the window depends on
  	 * the feature-remote value of Sequence Window: nothing stops the peer
  	 * from updating this value while we are busy adjusting SWL for the
  	 * first W packets (we would have to count from scratch again then).
  	 * Therefore it is safer to always make sure that the Sequence Window
  	 * is not artificially extended by a peer who grows SWL downwards by
  	 * continually updating the feature-remote Sequence-Window.
  	 * If sequence numbers wrap it is bad luck. But that will take a while
  	 * (48 bit), and this measure prevents Sequence-number attacks.
  	 */
  	if (before48(dp->dccps_swl, dp->dccps_isr))
  		dp->dccps_swl = dp->dccps_isr;

  	dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);

  }
  
  static inline void dccp_update_gss(struct sock *sk, u64 seq)
  {
  	struct dccp_sock *dp = dccp_sk(sk);

  	dp->dccps_gss = seq;
  	/* Ack validity window depends on local Sequence Window value (7.5.1) */
  	dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);

  	/* Adjust AWL so that it is not below ISS - see comment above for SWL */
  	if (before48(dp->dccps_awl, dp->dccps_iss))
  		dp->dccps_awl = dp->dccps_iss;

  	dp->dccps_awh = dp->dccps_gss;

  }

  static inline int dccp_ackvec_pending(const struct sock *sk)
  {
  	return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&
  	       !dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);
  }

  static inline int dccp_ack_pending(const struct sock *sk)
  {

  	return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);

  }

  int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
  int dccp_feat_finalise_settings(struct dccp_sock *dp);
  int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
  int dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*,
  			  struct sk_buff *skb);
  int dccp_feat_activate_values(struct sock *sk, struct list_head *fn);
  void dccp_feat_list_purge(struct list_head *fn_list);
  
  int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
  int dccp_insert_options_rsk(struct dccp_request_sock *, struct sk_buff *);

  u32 dccp_timestamp(void);
  void dccp_timestamping_init(void);
  int dccp_insert_option(struct sk_buff *skb, unsigned char option,
  		       const void *value, unsigned char len);

  #ifdef CONFIG_SYSCTL

  int dccp_sysctl_init(void);
  void dccp_sysctl_exit(void);

  #else
  static inline int dccp_sysctl_init(void)
  {
  	return 0;
  }
  
  static inline void dccp_sysctl_exit(void)
  {
  }
  #endif

  #endif /* _DCCP_H */