/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_DCCP_H
#define _LINUX_DCCP_H


#include <linux/in.h>
#include <linux/interrupt.h>
#include <linux/ktime.h>
#include <linux/list.h>
#include <linux/uio.h>
#include <linux/workqueue.h>

#include <net/inet_connection_sock.h>
#include <net/inet_sock.h>
#include <net/inet_timewait_sock.h>
#include <net/tcp_states.h>
#include <uapi/linux/dccp.h>

enum dccp_state {
	DCCP_OPEN	     = TCP_ESTABLISHED,
	DCCP_REQUESTING	     = TCP_SYN_SENT,
	DCCP_LISTEN	     = TCP_LISTEN,
	DCCP_RESPOND	     = TCP_SYN_RECV,
	/*
	 * States involved in closing a DCCP connection:
	 * 1) ACTIVE_CLOSEREQ is entered by a server sending a CloseReq.
	 *
	 * 2) CLOSING can have three different meanings (RFC 4340, 8.3):
	 *  a. Client has performed active-close, has sent a Close to the server
	 *     from state OPEN or PARTOPEN, and is waiting for the final Reset
	 *     (in this case, SOCK_DONE == 1).
	 *  b. Client is asked to perform passive-close, by receiving a CloseReq
	 *     in (PART)OPEN state. It sends a Close and waits for final Reset
	 *     (in this case, SOCK_DONE == 0).
	 *  c. Server performs an active-close as in (a), keeps TIMEWAIT state.
	 *
	 * 3) The following intermediate states are employed to give passively
	 *    closing nodes a chance to process their unread data:
	 *    - PASSIVE_CLOSE    (from OPEN => CLOSED) and
	 *    - PASSIVE_CLOSEREQ (from (PART)OPEN to CLOSING; case (b) above).
	 */
	DCCP_ACTIVE_CLOSEREQ = TCP_FIN_WAIT1,
	DCCP_PASSIVE_CLOSE   = TCP_CLOSE_WAIT,	/* any node receiving a Close */
	DCCP_CLOSING	     = TCP_CLOSING,
	DCCP_TIME_WAIT	     = TCP_TIME_WAIT,
	DCCP_CLOSED	     = TCP_CLOSE,
	DCCP_NEW_SYN_RECV    = TCP_NEW_SYN_RECV,
	DCCP_PARTOPEN	     = TCP_MAX_STATES,
	DCCP_PASSIVE_CLOSEREQ,			/* clients receiving CloseReq */
	DCCP_MAX_STATES
};

enum {
	DCCPF_OPEN	      = TCPF_ESTABLISHED,
	DCCPF_REQUESTING      = TCPF_SYN_SENT,
	DCCPF_LISTEN	      = TCPF_LISTEN,
	DCCPF_RESPOND	      = TCPF_SYN_RECV,
	DCCPF_ACTIVE_CLOSEREQ = TCPF_FIN_WAIT1,
	DCCPF_CLOSING	      = TCPF_CLOSING,
	DCCPF_TIME_WAIT	      = TCPF_TIME_WAIT,
	DCCPF_CLOSED	      = TCPF_CLOSE,
	DCCPF_NEW_SYN_RECV    = TCPF_NEW_SYN_RECV,
	DCCPF_PARTOPEN	      = (1 << DCCP_PARTOPEN),
};

static inline struct dccp_hdr *dccp_hdr(const struct sk_buff *skb)
{
	return (struct dccp_hdr *)skb_transport_header(skb);
}

static inline struct dccp_hdr *dccp_zeroed_hdr(struct sk_buff *skb, int headlen)
{
	skb_push(skb, headlen);
	skb_reset_transport_header(skb);
	return memset(skb_transport_header(skb), 0, headlen);
}

static inline struct dccp_hdr_ext *dccp_hdrx(const struct dccp_hdr *dh)
{
	return (struct dccp_hdr_ext *)((unsigned char *)dh + sizeof(*dh));
}

static inline unsigned int __dccp_basic_hdr_len(const struct dccp_hdr *dh)
{
	return sizeof(*dh) + (dh->dccph_x ? sizeof(struct dccp_hdr_ext) : 0);
}

static inline unsigned int dccp_basic_hdr_len(const struct sk_buff *skb)
{
	const struct dccp_hdr *dh = dccp_hdr(skb);
	return __dccp_basic_hdr_len(dh);
}

static inline __u64 dccp_hdr_seq(const struct dccp_hdr *dh)
{
	__u64 seq_nr =  ntohs(dh->dccph_seq);

	if (dh->dccph_x != 0)
		seq_nr = (seq_nr << 32) + ntohl(dccp_hdrx(dh)->dccph_seq_low);
	else
		seq_nr += (u32)dh->dccph_seq2 << 16;

	return seq_nr;
}

static inline struct dccp_hdr_request *dccp_hdr_request(struct sk_buff *skb)
{
	return (struct dccp_hdr_request *)(skb_transport_header(skb) +
					   dccp_basic_hdr_len(skb));
}

static inline struct dccp_hdr_ack_bits *dccp_hdr_ack_bits(const struct sk_buff *skb)
{
	return (struct dccp_hdr_ack_bits *)(skb_transport_header(skb) +
					    dccp_basic_hdr_len(skb));
}

static inline u64 dccp_hdr_ack_seq(const struct sk_buff *skb)
{
	const struct dccp_hdr_ack_bits *dhack = dccp_hdr_ack_bits(skb);
	return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) + ntohl(dhack->dccph_ack_nr_low);
}

static inline struct dccp_hdr_response *dccp_hdr_response(struct sk_buff *skb)
{
	return (struct dccp_hdr_response *)(skb_transport_header(skb) +
					    dccp_basic_hdr_len(skb));
}

static inline struct dccp_hdr_reset *dccp_hdr_reset(struct sk_buff *skb)
{
	return (struct dccp_hdr_reset *)(skb_transport_header(skb) +
					 dccp_basic_hdr_len(skb));
}

static inline unsigned int __dccp_hdr_len(const struct dccp_hdr *dh)
{
	return __dccp_basic_hdr_len(dh) +
	       dccp_packet_hdr_len(dh->dccph_type);
}

static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
{
	return __dccp_hdr_len(dccp_hdr(skb));
}

/**
 * struct dccp_request_sock  -  represent DCCP-specific connection request
 * @dreq_inet_rsk: structure inherited from
 * @dreq_iss: initial sequence number, sent on the first Response (RFC 4340, 7.1)
 * @dreq_gss: greatest sequence number sent (for retransmitted Responses)
 * @dreq_isr: initial sequence number received in the first Request
 * @dreq_gsr: greatest sequence number received (for retransmitted Request(s))
 * @dreq_service: service code present on the Request (there is just one)
 * @dreq_featneg: feature negotiation options for this connection
 * The following two fields are analogous to the ones in dccp_sock:
 * @dreq_timestamp_echo: last received timestamp to echo (13.1)
 * @dreq_timestamp_echo: the time of receiving the last @dreq_timestamp_echo
 */
struct dccp_request_sock {
	struct inet_request_sock dreq_inet_rsk;
	__u64			 dreq_iss;
	__u64			 dreq_gss;
	__u64			 dreq_isr;
	__u64			 dreq_gsr;
	__be32			 dreq_service;
	spinlock_t		 dreq_lock;
	struct list_head	 dreq_featneg;
	__u32			 dreq_timestamp_echo;
	__u32			 dreq_timestamp_time;
};

static inline struct dccp_request_sock *dccp_rsk(const struct request_sock *req)
{
	return (struct dccp_request_sock *)req;
}

extern struct inet_timewait_death_row dccp_death_row;

extern int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
			      struct sk_buff *skb);

struct dccp_options_received {
	u64	dccpor_ndp:48;
	u32	dccpor_timestamp;
	u32	dccpor_timestamp_echo;
	u32	dccpor_elapsed_time;
};

struct ccid;

enum dccp_role {
	DCCP_ROLE_UNDEFINED,
	DCCP_ROLE_LISTEN,
	DCCP_ROLE_CLIENT,
	DCCP_ROLE_SERVER,
};

struct dccp_service_list {
	__u32	dccpsl_nr;
	__be32	dccpsl_list[0];
};

#define DCCP_SERVICE_INVALID_VALUE htonl((__u32)-1)
#define DCCP_SERVICE_CODE_IS_ABSENT		0

static inline bool dccp_list_has_service(const struct dccp_service_list *sl,
					const __be32 service)
{
	if (likely(sl != NULL)) {
		u32 i = sl->dccpsl_nr;
		while (i--)
			if (sl->dccpsl_list[i] == service)
				return true;
	}
	return false;
}

struct dccp_ackvec;

/**
 * struct dccp_sock - DCCP socket state
 *
 * @dccps_swl - sequence number window low
 * @dccps_swh - sequence number window high
 * @dccps_awl - acknowledgement number window low
 * @dccps_awh - acknowledgement number window high
 * @dccps_iss - initial sequence number sent
 * @dccps_isr - initial sequence number received
 * @dccps_osr - first OPEN sequence number received
 * @dccps_gss - greatest sequence number sent
 * @dccps_gsr - greatest valid sequence number received
 * @dccps_gar - greatest valid ack number received on a non-Sync; initialized to %dccps_iss
 * @dccps_service - first (passive sock) or unique (active sock) service code
 * @dccps_service_list - second .. last service code on passive socket
 * @dccps_timestamp_echo - latest timestamp received on a TIMESTAMP option
 * @dccps_timestamp_time - time of receiving latest @dccps_timestamp_echo
 * @dccps_l_ack_ratio - feature-local Ack Ratio
 * @dccps_r_ack_ratio - feature-remote Ack Ratio
 * @dccps_l_seq_win - local Sequence Window (influences ack number validity)
 * @dccps_r_seq_win - remote Sequence Window (influences seq number validity)
 * @dccps_pcslen - sender   partial checksum coverage (via sockopt)
 * @dccps_pcrlen - receiver partial checksum coverage (via sockopt)
 * @dccps_send_ndp_count - local Send NDP Count feature (7.7.2)
 * @dccps_ndp_count - number of Non Data Packets since last data packet
 * @dccps_mss_cache - current value of MSS (path MTU minus header sizes)
 * @dccps_rate_last - timestamp for rate-limiting DCCP-Sync (RFC 4340, 7.5.4)
 * @dccps_featneg - tracks feature-negotiation state (mostly during handshake)
 * @dccps_hc_rx_ackvec - rx half connection ack vector
 * @dccps_hc_rx_ccid - CCID used for the receiver (or receiving half-connection)
 * @dccps_hc_tx_ccid - CCID used for the sender (or sending half-connection)
 * @dccps_options_received - parsed set of retrieved options
 * @dccps_qpolicy - TX dequeueing policy, one of %dccp_packet_dequeueing_policy
 * @dccps_tx_qlen - maximum length of the TX queue
 * @dccps_role - role of this sock, one of %dccp_role
 * @dccps_hc_rx_insert_options - receiver wants to add options when acking
 * @dccps_hc_tx_insert_options - sender wants to add options when sending
 * @dccps_server_timewait - server holds timewait state on close (RFC 4340, 8.3)
 * @dccps_sync_scheduled - flag which signals "send out-of-band message soon"
 * @dccps_xmitlet - tasklet scheduled by the TX CCID to dequeue data packets
 * @dccps_xmit_timer - used by the TX CCID to delay sending (rate-based pacing)
 * @dccps_syn_rtt - RTT sample from Request/Response exchange (in usecs)
 */
struct dccp_sock {
	/* inet_connection_sock has to be the first member of dccp_sock */
	struct inet_connection_sock	dccps_inet_connection;
#define dccps_syn_rtt			dccps_inet_connection.icsk_ack.lrcvtime
	__u64				dccps_swl;
	__u64				dccps_swh;
	__u64				dccps_awl;
	__u64				dccps_awh;
	__u64				dccps_iss;
	__u64				dccps_isr;
	__u64				dccps_osr;
	__u64				dccps_gss;
	__u64				dccps_gsr;
	__u64				dccps_gar;
	__be32				dccps_service;
	__u32				dccps_mss_cache;
	struct dccp_service_list	*dccps_service_list;
	__u32				dccps_timestamp_echo;
	__u32				dccps_timestamp_time;
	__u16				dccps_l_ack_ratio;
	__u16				dccps_r_ack_ratio;
	__u64				dccps_l_seq_win:48;
	__u64				dccps_r_seq_win:48;
	__u8				dccps_pcslen:4;
	__u8				dccps_pcrlen:4;
	__u8				dccps_send_ndp_count:1;
	__u64				dccps_ndp_count:48;
	unsigned long			dccps_rate_last;
	struct list_head		dccps_featneg;
	struct dccp_ackvec		*dccps_hc_rx_ackvec;
	struct ccid			*dccps_hc_rx_ccid;
	struct ccid			*dccps_hc_tx_ccid;
	struct dccp_options_received	dccps_options_received;
	__u8				dccps_qpolicy;
	__u32				dccps_tx_qlen;
	enum dccp_role			dccps_role:2;
	__u8				dccps_hc_rx_insert_options:1;
	__u8				dccps_hc_tx_insert_options:1;
	__u8				dccps_server_timewait:1;
	__u8				dccps_sync_scheduled:1;
	struct tasklet_struct		dccps_xmitlet;
	struct timer_list		dccps_xmit_timer;
};

static inline struct dccp_sock *dccp_sk(const struct sock *sk)
{
	return (struct dccp_sock *)sk;
}

static inline const char *dccp_role(const struct sock *sk)
{
	switch (dccp_sk(sk)->dccps_role) {
	case DCCP_ROLE_UNDEFINED: return "undefined";
	case DCCP_ROLE_LISTEN:	  return "listen";
	case DCCP_ROLE_SERVER:	  return "server";
	case DCCP_ROLE_CLIENT:	  return "client";
	}
	return NULL;
}

extern void dccp_syn_ack_timeout(const struct request_sock *req);

#endif /* _LINUX_DCCP_H */