[linux.git] / net / dccp / dccp.h

#ifndef _DCCP_H
#define _DCCP_H
/*
 *  net/dccp/dccp.h
 *
 *  An implementation of the DCCP protocol
 *  Copyright (c) 2005 Arnaldo Carvalho de Melo <[email protected]>
 *  Copyright (c) 2005-6 Ian McDonald <[email protected]>
 *
 *	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/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()\n", ##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);
unsigned int 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 */
Commit	Line	Data
7c657876 ACM	1	#ifndef _DCCP_H
	2	#define _DCCP_H
	3	/*
	4	* net/dccp/dccp.h
	5	*
	6	* An implementation of the DCCP protocol
1bc09869	7	* Copyright (c) 2005 Arnaldo Carvalho de Melo <[email protected]>
e6bccd35	8	* Copyright (c) 2005-6 Ian McDonald <[email protected]>
7c657876 ACM	9	*
	10	* This program is free software; you can redistribute it and/or modify it
	11	* under the terms of the GNU General Public License version 2 as
	12	* published by the Free Software Foundation.
	13	*/
	14
	15	#include <linux/dccp.h>
9823b7b5	16	#include <linux/ktime.h>
7c657876 ACM	17	#include <net/snmp.h>
	18	#include <net/sock.h>
	19	#include <net/tcp.h>
ae31c339	20	#include "ackvec.h"
7c657876	21
59348b19 GR	22	/*
	23	* DCCP - specific warning and debugging macros.
	24	*/
c0560b9c JP	25	#define DCCP_WARN(fmt, ...) \
c0560b9c JP	26	net_warn_ratelimited("%s: " fmt, __func__, ##__VA_ARGS__)
59348b19	27	#define DCCP_CRIT(fmt, a...) printk(KERN_CRIT fmt " at %s:%d/%s()\n", ##a, \
0dc47877	28	__FILE__, __LINE__, __func__)
59348b19 GR	29	#define DCCP_BUG(a...) do { DCCP_CRIT("BUG: " a); dump_stack(); } while(0)
	30	#define DCCP_BUG_ON(cond) do { if (unlikely((cond) != 0)) \
	31	DCCP_BUG("\"%s\" holds (exception!)", \
	32	__stringify(cond)); \
3c695262 GR	33	} while (0)
3c695262 GR	34
84116716 GR	35	#define DCCP_PRINTK(enable, fmt, args...) do { if (enable) \
84116716 GR	36	printk(fmt, ##args); \
c9eaf173	37	} while(0)
84116716	38	#define DCCP_PR_DEBUG(enable, fmt, a...) DCCP_PRINTK(enable, KERN_DEBUG \
0dc47877	39	"%s: " fmt, __func__, ##a)
84116716	40
725ba8ee	41	#ifdef CONFIG_IP_DCCP_DEBUG
eb939922	42	extern bool dccp_debug;
84116716 GR	43	#define dccp_pr_debug(format, a...) DCCP_PR_DEBUG(dccp_debug, format, ##a)
84116716 GR	44	#define dccp_pr_debug_cat(format, a...) DCCP_PRINTK(dccp_debug, format, ##a)
f3f3abb6	45	#define dccp_debug(fmt, a...) dccp_pr_debug_cat(KERN_DEBUG fmt, ##a)
7c657876 ACM	46	#else
	47	#define dccp_pr_debug(format, a...)
	48	#define dccp_pr_debug_cat(format, a...)
f3f3abb6	49	#define dccp_debug(format, a...)
7c657876 ACM	50	#endif
	51
	52	extern struct inet_hashinfo dccp_hashinfo;
	53
dd24c001	54	extern struct percpu_counter dccp_orphan_count;
7c657876	55
a402a5aa	56	void dccp_time_wait(struct sock *sk, int state, int timeo);
7c657876	57
60361be1 GR	58	/*
	59	* Set safe upper bounds for header and option length. Since Data Offset is 8
	60	* bits (RFC 4340, sec. 5.1), the total header length can never be more than
	61	* 4 * 255 = 1020 bytes. The largest possible header length is 28 bytes (X=1):
	62	* - DCCP-Response with ACK Subheader and 4 bytes of Service code OR
	63	* - DCCP-Reset with ACK Subheader and 4 bytes of Reset Code fields
	64	* Hence a safe upper bound for the maximum option length is 1020-28 = 992
	65	*/
86739fb9	66	#define MAX_DCCP_SPECIFIC_HEADER (255 * sizeof(uint32_t))
60361be1 GR	67	#define DCCP_MAX_PACKET_HDR 28
	68	#define DCCP_MAX_OPT_LEN (MAX_DCCP_SPECIFIC_HEADER - DCCP_MAX_PACKET_HDR)
	69	#define MAX_DCCP_HEADER (MAX_DCCP_SPECIFIC_HEADER + MAX_HEADER)
7c657876	70
86739fb9 GR	71	/* Upper bound for initial feature-negotiation overhead (padded to 32 bits) */
	72	#define DCCP_FEATNEG_OVERHEAD (32 * sizeof(uint32_t))
	73
7c657876 ACM	74	#define DCCP_TIMEWAIT_LEN (60 * HZ) /* how long to wait to destroy TIME-WAIT
	75	* state, about 60 seconds */
	76
0e64e94e	77	/* RFC 1122, 4.2.3.1 initial RTO value */
95c96174	78	#define DCCP_TIMEOUT_INIT ((unsigned int)(3 * HZ))
7c657876	79
28be5440 GR	80	/*
	81	* The maximum back-off value for retransmissions. This is needed for
	82	* - retransmitting client-Requests (sec. 8.1.1),
	83	* - retransmitting Close/CloseReq when closing (sec. 8.3),
	84	* - feature-negotiation retransmission (sec. 6.6.3),
	85	* - Acks in client-PARTOPEN state (sec. 8.1.5).
	86	*/
95c96174	87	#define DCCP_RTO_MAX ((unsigned int)(64 * HZ))
4712a792	88
954c2db8 GR	89	/*
	90	* RTT sampling: sanity bounds and fallback RTT value from RFC 4340, section 3.4
	91	*/
4712a792	92	#define DCCP_SANE_RTT_MIN 100
954c2db8 GR	93	#define DCCP_FALLBACK_RTT (USEC_PER_SEC / 5)
954c2db8 GR	94	#define DCCP_SANE_RTT_MAX (3 * USEC_PER_SEC)
4712a792	95
2e2e9e92 GR	96	/* sysctl variables for DCCP */
	97	extern int sysctl_dccp_request_retries;
	98	extern int sysctl_dccp_retries1;
	99	extern int sysctl_dccp_retries2;
b1308dc0	100	extern int sysctl_dccp_tx_qlen;
a94f0f97	101	extern int sysctl_dccp_sync_ratelimit;
2e2e9e92	102
6b811d43 GR	103	/*
	104	* 48-bit sequence number arithmetic (signed and unsigned)
	105	*/
	106	#define INT48_MIN 0x800000000000LL /* 2^47 */
	107	#define UINT48_MAX 0xFFFFFFFFFFFFLL /* 2^48 - 1 */
	108	#define COMPLEMENT48(x) (0x1000000000000LL - (x)) /* 2^48 - x */
	109	#define TO_SIGNED48(x) (((x) < INT48_MIN)? (x) : -COMPLEMENT48( (x)))
	110	#define TO_UNSIGNED48(x) (((x) >= 0)? (x) : COMPLEMENT48(-(x)))
	111	#define ADD48(a, b) (((a) + (b)) & UINT48_MAX)
	112	#define SUB48(a, b) ADD48((a), COMPLEMENT48(b))
	113
	114	static inline void dccp_set_seqno(u64 *seqno, u64 value)
	115	{
	116	*seqno = value & UINT48_MAX;
	117	}
	118
	119	static inline void dccp_inc_seqno(u64 *seqno)
	120	{
	121	seqno = ADD48(seqno, 1);
	122	}
	123
0aec51c8 GR	124	/* signed mod-2^48 distance: pos. if seqno1 < seqno2, neg. if seqno1 > seqno2 */
0aec51c8 GR	125	static inline s64 dccp_delta_seqno(const u64 seqno1, const u64 seqno2)
6b811d43	126	{
0aec51c8 GR	127	u64 delta = SUB48(seqno2, seqno1);
	128
	129	return TO_SIGNED48(delta);
6b811d43 GR	130	}
6b811d43 GR	131
7c657876	132	/* is seq1 < seq2 ? */
a10cedd4	133	static inline int before48(const u64 seq1, const u64 seq2)
7c657876	134	{
d52de17b	135	return (s64)((seq2 << 16) - (seq1 << 16)) > 0;
7c657876 ACM	136	}
	137
	138	/* is seq1 > seq2 ? */
d52de17b	139	#define after48(seq1, seq2) before48(seq2, seq1)
7c657876 ACM	140
7c657876 ACM	141	/* is seq2 <= seq1 <= seq3 ? */
a10cedd4	142	static inline int between48(const u64 seq1, const u64 seq2, const u64 seq3)
7c657876 ACM	143	{
	144	return (seq3 << 16) - (seq2 << 16) >= (seq1 << 16) - (seq2 << 16);
	145	}
	146
	147	static inline u64 max48(const u64 seq1, const u64 seq2)
	148	{
	149	return after48(seq1, seq2) ? seq1 : seq2;
	150	}
	151
2013c7e3	152	/**
d196c9a5 IC	153	* dccp_loss_count - Approximate the number of lost data packets in a burst loss
	154	* @s1: last known sequence number before the loss ('hole')
	155	* @s2: first sequence number seen after the 'hole'
2013c7e3	156	* @ndp: NDP count on packet with sequence number @s2
2013c7e3	157	*/
d196c9a5	158	static inline u64 dccp_loss_count(const u64 s1, const u64 s2, const u64 ndp)
2013c7e3 GR	159	{
	160	s64 delta = dccp_delta_seqno(s1, s2);
	161
547b792c	162	WARN_ON(delta < 0);
d196c9a5 IC	163	delta -= ndp + 1;
	164
	165	return delta > 0 ? delta : 0;
	166	}
	167
	168	/**
	169	* dccp_loss_free - Evaluate condition for data loss from RFC 4340, 7.7.1
	170	*/
	171	static inline bool dccp_loss_free(const u64 s1, const u64 s2, const u64 ndp)
	172	{
	173	return dccp_loss_count(s1, s2, ndp) == 0;
2013c7e3 GR	174	}
2013c7e3 GR	175
7c657876 ACM	176	enum {
	177	DCCP_MIB_NUM = 0,
	178	DCCP_MIB_ACTIVEOPENS, /* ActiveOpens */
	179	DCCP_MIB_ESTABRESETS, /* EstabResets */
	180	DCCP_MIB_CURRESTAB, /* CurrEstab */
c9eaf173	181	DCCP_MIB_OUTSEGS, /* OutSegs */
7c657876 ACM	182	DCCP_MIB_OUTRSTS,
	183	DCCP_MIB_ABORTONTIMEOUT,
	184	DCCP_MIB_TIMEOUTS,
	185	DCCP_MIB_ABORTFAILED,
	186	DCCP_MIB_PASSIVEOPENS,
	187	DCCP_MIB_ATTEMPTFAILS,
	188	DCCP_MIB_OUTDATAGRAMS,
	189	DCCP_MIB_INERRS,
	190	DCCP_MIB_OPTMANDATORYERROR,
	191	DCCP_MIB_INVALIDOPT,
	192	__DCCP_MIB_MAX
	193	};
	194
	195	#define DCCP_MIB_MAX __DCCP_MIB_MAX
	196	struct dccp_mib {
	197	unsigned long mibs[DCCP_MIB_MAX];
ec733b15	198	};
7c657876 ACM	199
7c657876 ACM	200	DECLARE_SNMP_STAT(struct dccp_mib, dccp_statistics);
aa62d76b	201	#define DCCP_INC_STATS(field) SNMP_INC_STATS(dccp_statistics, field)
13415e46	202	#define __DCCP_INC_STATS(field) __SNMP_INC_STATS(dccp_statistics, field)
aa62d76b	203	#define DCCP_DEC_STATS(field) SNMP_DEC_STATS(dccp_statistics, field)
7c657876	204
6f4e5fff GR	205	/*
	206	* Checksumming routines
	207	*/
e961811f	208	static inline unsigned int dccp_csum_coverage(const struct sk_buff *skb)
6f4e5fff GR	209	{
	210	const struct dccp_hdr* dh = dccp_hdr(skb);
	211
	212	if (dh->dccph_cscov == 0)
	213	return skb->len;
	214	return (dh->dccph_doff + dh->dccph_cscov - 1) * sizeof(u32);
	215	}
	216
	217	static inline void dccp_csum_outgoing(struct sk_buff *skb)
	218	{
e961811f	219	unsigned int cov = dccp_csum_coverage(skb);
6f4e5fff GR	220
	221	if (cov >= skb->len)
	222	dccp_hdr(skb)->dccph_cscov = 0;
	223
	224	skb->csum = skb_checksum(skb, 0, (cov > skb->len)? skb->len : cov, 0);
	225	}
	226
a402a5aa	227	void dccp_v4_send_check(struct sock sk, struct sk_buff skb);
6f4e5fff	228
a402a5aa	229	int dccp_retransmit_skb(struct sock *sk);
7c657876	230
a402a5aa	231	void dccp_send_ack(struct sock *sk);
a00e7444	232	void dccp_reqsk_send_ack(const struct sock sk, struct sk_buff skb,
a402a5aa	233	struct request_sock *rsk);
8a73cd09	234
a402a5aa JP	235	void dccp_send_sync(struct sock *sk, const u64 seq,
a402a5aa JP	236	const enum dccp_pkt_type pkt_type);
7c657876	237
871a2c16 TG	238	/*
	239	* TX Packet Dequeueing Interface
	240	*/
a402a5aa JP	241	void dccp_qpolicy_push(struct sock sk, struct sk_buff skb);
	242	bool dccp_qpolicy_full(struct sock *sk);
	243	void dccp_qpolicy_drop(struct sock sk, struct sk_buff skb);
	244	struct sk_buff dccp_qpolicy_top(struct sock sk);
	245	struct sk_buff dccp_qpolicy_pop(struct sock sk);
	246	bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param);
871a2c16 TG	247
	248	/*
	249	* TX Packet Output and TX Timers
	250	*/
a402a5aa JP	251	void dccp_write_xmit(struct sock *sk);
	252	void dccp_write_space(struct sock *sk);
	253	void dccp_flush_write_queue(struct sock sk, long time_budget);
27258ee5	254
a402a5aa	255	void dccp_init_xmit_timers(struct sock *sk);
7c657876 ACM	256	static inline void dccp_clear_xmit_timers(struct sock *sk)
	257	{
	258	inet_csk_clear_xmit_timers(sk);
	259	}
	260
a402a5aa	261	unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu);
7c657876	262
a402a5aa	263	const char *dccp_packet_name(const int type);
7c657876	264
a402a5aa JP	265	void dccp_set_state(struct sock *sk, const int state);
a402a5aa JP	266	void dccp_done(struct sock *sk);
7c657876	267
a402a5aa JP	268	int dccp_reqsk_init(struct request_sock rq, struct dccp_sock const dp,
a402a5aa JP	269	struct sk_buff const *skb);
7c657876	270
a402a5aa	271	int dccp_v4_conn_request(struct sock sk, struct sk_buff skb);
7c657876	272
54105f98	273	struct sock dccp_create_openreq_child(const struct sock sk,
a402a5aa JP	274	const struct request_sock *req,
a402a5aa JP	275	const struct sk_buff *skb);
7c657876	276
a402a5aa	277	int dccp_v4_do_rcv(struct sock sk, struct sk_buff skb);
7c657876	278
0c27171e	279	struct sock dccp_v4_request_recv_sock(const struct sock sk, struct sk_buff *skb,
a402a5aa	280	struct request_sock *req,
5e0724d0 ED	281	struct dst_entry *dst,
	282	struct request_sock *req_unhash,
	283	bool *own_req);
a402a5aa	284	struct sock dccp_check_req(struct sock sk, struct sk_buff *skb,
52452c54	285	struct request_sock *req);
7c657876	286
a402a5aa JP	287	int dccp_child_process(struct sock parent, struct sock child,
	288	struct sk_buff *skb);
	289	int dccp_rcv_state_process(struct sock sk, struct sk_buff skb,
	290	struct dccp_hdr *dh, unsigned int len);
	291	int dccp_rcv_established(struct sock sk, struct sk_buff skb,
	292	const struct dccp_hdr *dh, const unsigned int len);
7c657876	293
a402a5aa JP	294	int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
a402a5aa JP	295	void dccp_destroy_sock(struct sock *sk);
f21e68ca	296
a402a5aa	297	void dccp_close(struct sock *sk, long timeout);
802885fc	298	struct sk_buff dccp_make_response(const struct sock sk, struct dst_entry *dst,
a402a5aa	299	struct request_sock *req);
7c657876	300
a402a5aa JP	301	int dccp_connect(struct sock *sk);
	302	int dccp_disconnect(struct sock *sk, int flags);
	303	int dccp_getsockopt(struct sock *sk, int level, int optname,
	304	char __user optval, int __user optlen);
	305	int dccp_setsockopt(struct sock *sk, int level, int optname,
	306	char __user *optval, unsigned int optlen);
3fdadf7d	307	#ifdef CONFIG_COMPAT
a402a5aa JP	308	int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
	309	char __user optval, int __user optlen);
	310	int compat_dccp_setsockopt(struct sock *sk, int level, int optname,
	311	char __user *optval, unsigned int optlen);
3fdadf7d	312	#endif
a402a5aa	313	int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);
1b784140 YX	314	int dccp_sendmsg(struct sock sk, struct msghdr msg, size_t size);
	315	int dccp_recvmsg(struct sock sk, struct msghdr msg, size_t len, int nonblock,
	316	int flags, int *addr_len);
a402a5aa JP	317	void dccp_shutdown(struct sock *sk, int how);
	318	int inet_dccp_listen(struct socket *sock, int backlog);
	319	unsigned int dccp_poll(struct file file, struct socket sock,
	320	poll_table *wait);
	321	int dccp_v4_connect(struct sock sk, struct sockaddr uaddr, int addr_len);
85645bab	322	void dccp_req_err(struct sock *sk, u64 seq);
a402a5aa JP	323
	324	struct sk_buff dccp_ctl_make_reset(struct sock sk, struct sk_buff *skb);
	325	int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
	326	void dccp_send_close(struct sock *sk, const int active);
	327	int dccp_invalid_packet(struct sk_buff *skb);
	328	u32 dccp_sample_rtt(struct sock *sk, long delta);
f21e68ca	329
45ae74f5	330	static inline bool dccp_bad_service_code(const struct sock *sk,
60fe62e7	331	const __be32 service)
f21e68ca ACM	332	{
	333	const struct dccp_sock *dp = dccp_sk(sk);
	334
	335	if (dp->dccps_service == service)
45ae74f5	336	return false;
f21e68ca ACM	337	return !dccp_list_has_service(dp->dccps_service_list, service);
f21e68ca ACM	338	}
7c657876	339
0430ee34 GR	340	/**
	341	* dccp_skb_cb - DCCP per-packet control information
	342	* @dccpd_type: one of %dccp_pkt_type (or unknown)
	343	* @dccpd_ccval: CCVal field (5.1), see e.g. RFC 4342, 8.1
	344	* @dccpd_reset_code: one of %dccp_reset_codes
	345	* @dccpd_reset_data: Data1..3 fields (depend on @dccpd_reset_code)
	346	* @dccpd_opt_len: total length of all options (5.8) in the packet
	347	* @dccpd_seq: sequence number
	348	* @dccpd_ack_seq: acknowledgment number subheader field value
2c53040f	349	*
0430ee34 GR	350	* This is used for transmission as well as for reception.
0430ee34 GR	351	*/
7c657876	352	struct dccp_skb_cb {
028b0275 PM	353	union {
028b0275 PM	354	struct inet_skb_parm h4;
dfd56b8b	355	#if IS_ENABLED(CONFIG_IPV6)
028b0275 PM	356	struct inet6_skb_parm h6;
	357	#endif
	358	} header;
67e6b629 ACM	359	__u8 dccpd_type:4;
67e6b629 ACM	360	__u8 dccpd_ccval:4;
0430ee34 GR	361	__u8 dccpd_reset_code,
0430ee34 GR	362	dccpd_reset_data[3];
67e6b629	363	__u16 dccpd_opt_len;
7c657876 ACM	364	__u64 dccpd_seq;
7c657876 ACM	365	__u64 dccpd_ack_seq;
7c657876 ACM	366	};
	367
	368	#define DCCP_SKB_CB(__skb) ((struct dccp_skb_cb *)&((__skb)->cb[0]))
	369
2180c41c	370	/* RFC 4340, sec. 7.7 */
7c657876 ACM	371	static inline int dccp_non_data_packet(const struct sk_buff *skb)
	372	{
	373	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
	374
	375	return type == DCCP_PKT_ACK \|\|
	376	type == DCCP_PKT_CLOSE \|\|
	377	type == DCCP_PKT_CLOSEREQ \|\|
	378	type == DCCP_PKT_RESET \|\|
	379	type == DCCP_PKT_SYNC \|\|
	380	type == DCCP_PKT_SYNCACK;
	381	}
	382
2180c41c GR	383	/* RFC 4340, sec. 7.7 */
	384	static inline int dccp_data_packet(const struct sk_buff *skb)
	385	{
	386	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
	387
	388	return type == DCCP_PKT_DATA \|\|
	389	type == DCCP_PKT_DATAACK \|\|
	390	type == DCCP_PKT_REQUEST \|\|
	391	type == DCCP_PKT_RESPONSE;
	392	}
	393
7c657876 ACM	394	static inline int dccp_packet_without_ack(const struct sk_buff *skb)
	395	{
	396	const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
	397
	398	return type == DCCP_PKT_DATA \|\| type == DCCP_PKT_REQUEST;
	399	}
	400
6b811d43	401	#define DCCP_PKT_WITHOUT_ACK_SEQ (UINT48_MAX << 2)
7c657876 ACM	402
	403	static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss)
	404	{
7690af3f ACM	405	struct dccp_hdr_ext dhx = (struct dccp_hdr_ext )((void *)dh +
7690af3f ACM	406	sizeof(*dh));
60fe62e7 AB	407	dh->dccph_seq2 = 0;
60fe62e7 AB	408	dh->dccph_seq = htons((gss >> 32) & 0xfffff);
7c657876 ACM	409	dhx->dccph_seq_low = htonl(gss & 0xffffffff);
	410	}
	411
7690af3f ACM	412	static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
7690af3f ACM	413	const u64 gsr)
7c657876	414	{
60fe62e7 AB	415	dhack->dccph_reserved1 = 0;
60fe62e7 AB	416	dhack->dccph_ack_nr_high = htons(gsr >> 32);
7c657876 ACM	417	dhack->dccph_ack_nr_low = htonl(gsr & 0xffffffff);
	418	}
	419
	420	static inline void dccp_update_gsr(struct sock *sk, u64 seq)
	421	{
	422	struct dccp_sock *dp = dccp_sk(sk);
7c657876	423
763dadd4 SJ	424	if (after48(seq, dp->dccps_gsr))
763dadd4 SJ	425	dp->dccps_gsr = seq;
792b4878 GR	426	/* Sequence validity window depends on remote Sequence Window (7.5.1) */
792b4878 GR	427	dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
0b53d460 GR	428	/*
	429	* Adjust SWL so that it is not below ISR. In contrast to RFC 4340,
	430	* 7.5.1 we perform this check beyond the initial handshake: W/W' are
	431	* always > 32, so for the first W/W' packets in the lifetime of a
	432	* connection we always have to adjust SWL.
	433	* A second reason why we are doing this is that the window depends on
	434	* the feature-remote value of Sequence Window: nothing stops the peer
	435	* from updating this value while we are busy adjusting SWL for the
	436	* first W packets (we would have to count from scratch again then).
	437	* Therefore it is safer to always make sure that the Sequence Window
	438	* is not artificially extended by a peer who grows SWL downwards by
	439	* continually updating the feature-remote Sequence-Window.
	440	* If sequence numbers wrap it is bad luck. But that will take a while
	441	* (48 bit), and this measure prevents Sequence-number attacks.
	442	*/
	443	if (before48(dp->dccps_swl, dp->dccps_isr))
	444	dp->dccps_swl = dp->dccps_isr;
792b4878	445	dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);
7c657876 ACM	446	}
	447
	448	static inline void dccp_update_gss(struct sock *sk, u64 seq)
	449	{
	450	struct dccp_sock *dp = dccp_sk(sk);
7c657876	451
792b4878 GR	452	dp->dccps_gss = seq;
	453	/* Ack validity window depends on local Sequence Window value (7.5.1) */
	454	dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);
0b53d460 GR	455	/* Adjust AWL so that it is not below ISS - see comment above for SWL */
	456	if (before48(dp->dccps_awl, dp->dccps_iss))
	457	dp->dccps_awl = dp->dccps_iss;
792b4878	458	dp->dccps_awh = dp->dccps_gss;
7c657876	459	}
c9eaf173	460
b3d14bff GR	461	static inline int dccp_ackvec_pending(const struct sock *sk)
	462	{
	463	return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&
	464	!dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);
	465	}
	466
ae31c339 ACM	467	static inline int dccp_ack_pending(const struct sock *sk)
ae31c339 ACM	468	{
b3d14bff	469	return dccp_ackvec_pending(sk) \|\| inet_csk_ack_scheduled(sk);
ae31c339	470	}
7c657876	471
a402a5aa JP	472	int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
	473	int dccp_feat_finalise_settings(struct dccp_sock *dp);
	474	int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
	475	int dccp_feat_insert_opts(struct dccp_sock, struct dccp_request_sock,
	476	struct sk_buff *skb);
	477	int dccp_feat_activate_values(struct sock sk, struct list_head fn);
	478	void dccp_feat_list_purge(struct list_head *fn_list);
	479
	480	int dccp_insert_options(struct sock sk, struct sk_buff skb);
	481	int dccp_insert_options_rsk(struct dccp_request_sock , struct sk_buff );
a402a5aa JP	482	u32 dccp_timestamp(void);
	483	void dccp_timestamping_init(void);
	484	int dccp_insert_option(struct sk_buff *skb, unsigned char option,
	485	const void *value, unsigned char len);
7c657876	486
e55d912f	487	#ifdef CONFIG_SYSCTL
a402a5aa JP	488	int dccp_sysctl_init(void);
a402a5aa JP	489	void dccp_sysctl_exit(void);
e55d912f ACM	490	#else
	491	static inline int dccp_sysctl_init(void)
	492	{
	493	return 0;
	494	}
	495
	496	static inline void dccp_sysctl_exit(void)
	497	{
	498	}
	499	#endif
	500
7c657876	501	#endif /* _DCCP_H */