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linux/net/dccp/dccp.h
Gerrit Renker d7dc7e5f49 dccp ccid-2: Implementation of circular Ack Vector buffer with overflow handling 
This completes the implementation of a circular buffer for Ack Vectors, by 
extending the current (linear array-based) implementation.  The changes are:

 (a) An `overflow' flag to deal with the case of overflow. As before, dynamic
     growth of the buffer will not be supported; but code will be added to deal
     robustly with overflowing Ack Vector buffers.

 (b) A `tail_seqno' field. When naively implementing the algorithm of Appendix A
     in RFC 4340, problems arise whenever subsequent Ack Vector records overlap,
     which can bring the entire run length calculation completely out of synch.
     (This is documented on http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/\
                                             ack_vectors/tracking_tail_ackno/ .)
 (c) The buffer lengthi is now computed dynamically (i.e. current fill level),
     as the span between head to tail.

As a result, dccp_ackvec_pending() is now simpler - the #ifdef is no longer 
necessary since buf_empty is always true when IP_DCCP_ACKVEC is not configured.

Note on overflow handling: 
-------------------------
 The Ack Vector code previously simply started to drop packets when the
 Ack Vector buffer overflowed. This means that the userspace application
 will not be able to receive, only because of an Ack Vector storage problem.
 
 Furthermore, overflow may be transient, so that applications may later
 recover from the overflow. Recovering from dropped packets is more difficult
 (e.g. video key frames).
 
 Hence the patch uses a different policy: when the buffer overflows, the oldest
 entries are subsequently overwritten. This has a higher chance of recovery.
 Details are on http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/ack_vectors/

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
2008-09-04 07:45:36 +02:00

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#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>
*
* 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, a...) LIMIT_NETDEBUG(KERN_WARNING "%s: " fmt, \
__func__, ##a)
#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 int 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 atomic_t dccp_orphan_count;
extern 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)(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)(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)
/* Maximal interval between probes for local resources. */
#define DCCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ / 2U))
/* 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_free - Evaluates condition for data loss from RFC 4340, 7.7.1
* @s1: start sequence number
* @s2: end sequence number
* @ndp: NDP count on packet with sequence number @s2
* Returns true if the sequence range s1...s2 has no data loss.
*/
static inline bool dccp_loss_free(const u64 s1, const u64 s2, const u64 ndp)
{
s64 delta = dccp_delta_seqno(s1, s2);
WARN_ON(delta < 0);
return (u64)delta <= ndp + 1;
}
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];
} __SNMP_MIB_ALIGN__;
DECLARE_SNMP_STAT(struct dccp_mib, dccp_statistics);
#define DCCP_INC_STATS(field) SNMP_INC_STATS(dccp_statistics, field)
#define DCCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(dccp_statistics, field)
#define DCCP_INC_STATS_USER(field) SNMP_INC_STATS_USER(dccp_statistics, field)
#define DCCP_DEC_STATS(field) SNMP_DEC_STATS(dccp_statistics, field)
#define DCCP_ADD_STATS_BH(field, val) \
SNMP_ADD_STATS_BH(dccp_statistics, field, val)
#define DCCP_ADD_STATS_USER(field, val) \
SNMP_ADD_STATS_USER(dccp_statistics, field, val)
/*
* 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);
}
extern void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb);
extern int dccp_retransmit_skb(struct sock *sk);
extern void dccp_send_ack(struct sock *sk);
extern void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
struct request_sock *rsk);
extern void dccp_send_sync(struct sock *sk, const u64 seq,
const enum dccp_pkt_type pkt_type);
extern void dccp_write_xmit(struct sock *sk, int block);
extern void dccp_write_space(struct sock *sk);
extern void dccp_init_xmit_timers(struct sock *sk);
static inline void dccp_clear_xmit_timers(struct sock *sk)
{
inet_csk_clear_xmit_timers(sk);
}
extern unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu);
extern const char *dccp_packet_name(const int type);
extern const char *dccp_state_name(const int state);
extern void dccp_set_state(struct sock *sk, const int state);
extern void dccp_done(struct sock *sk);
extern int dccp_reqsk_init(struct request_sock *rq, struct dccp_sock const *dp,
struct sk_buff const *skb);
extern int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
extern struct sock *dccp_create_openreq_child(struct sock *sk,
const struct request_sock *req,
const struct sk_buff *skb);
extern int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
extern struct sock *dccp_v4_request_recv_sock(struct sock *sk,
struct sk_buff *skb,
struct request_sock *req,
struct dst_entry *dst);
extern struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct request_sock **prev);
extern int dccp_child_process(struct sock *parent, struct sock *child,
struct sk_buff *skb);
extern int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
struct dccp_hdr *dh, unsigned len);
extern int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
const struct dccp_hdr *dh, const unsigned len);
extern int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
extern void dccp_destroy_sock(struct sock *sk);
extern void dccp_close(struct sock *sk, long timeout);
extern struct sk_buff *dccp_make_response(struct sock *sk,
struct dst_entry *dst,
struct request_sock *req);
extern int dccp_connect(struct sock *sk);
extern int dccp_disconnect(struct sock *sk, int flags);
extern int dccp_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen);
extern int dccp_setsockopt(struct sock *sk, int level, int optname,
char __user *optval, int optlen);
#ifdef CONFIG_COMPAT
extern int compat_dccp_getsockopt(struct sock *sk,
int level, int optname,
char __user *optval, int __user *optlen);
extern int compat_dccp_setsockopt(struct sock *sk,
int level, int optname,
char __user *optval, int optlen);
#endif
extern int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);
extern int dccp_sendmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg, size_t size);
extern int dccp_recvmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg, size_t len, int nonblock,
int flags, int *addr_len);
extern void dccp_shutdown(struct sock *sk, int how);
extern int inet_dccp_listen(struct socket *sock, int backlog);
extern unsigned int dccp_poll(struct file *file, struct socket *sock,
poll_table *wait);
extern int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
int addr_len);
extern struct sk_buff *dccp_ctl_make_reset(struct sock *sk,
struct sk_buff *skb);
extern int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
extern void dccp_send_close(struct sock *sk, const int active);
extern int dccp_invalid_packet(struct sk_buff *skb);
extern u32 dccp_sample_rtt(struct sock *sk, long delta);
static inline int 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 0;
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 defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
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);
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);
}
extern int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
extern int dccp_feat_finalise_settings(struct dccp_sock *dp);
extern int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
extern int dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*,
struct sk_buff *skb);
extern int dccp_feat_activate_values(struct sock *sk, struct list_head *fn);
extern void dccp_feat_list_purge(struct list_head *fn_list);
extern int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
extern int dccp_insert_options_rsk(struct dccp_request_sock*, struct sk_buff*);
extern int dccp_insert_option_elapsed_time(struct sock *sk,
struct sk_buff *skb,
u32 elapsed_time);
extern u32 dccp_timestamp(void);
extern void dccp_timestamping_init(void);
extern int dccp_insert_option_timestamp(struct sock *sk,
struct sk_buff *skb);
extern int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
unsigned char option,
const void *value, unsigned char len);
#ifdef CONFIG_SYSCTL
extern int dccp_sysctl_init(void);
extern 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 */
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