/*
* net/dccp/ackvec.h
*
- * An implementation of the DCCP protocol
+ * An implementation of Ack Vectors for the DCCP protocol
+ * Copyright (c) 2007 University of Aberdeen, Scotland, UK
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com>
- *
* 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/compiler.h>
-#include <linux/ktime.h>
#include <linux/list.h>
#include <linux/types.h>
-/* We can spread an ack vector across multiple options */
-#define DCCP_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * 2)
+/*
+ * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN,
+ * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1
+ * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives
+ * more headroom if Ack Ratio is higher or when the sender acknowledges slowly.
+ * The maximum value is bounded by the u16 types for indices and functions.
+ */
+#define DCCPAV_NUM_ACKVECS 2
+#define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
/* Estimated minimum average Ack Vector length - used for updating MPS */
#define DCCPAV_MIN_OPTLEN 16
-#define DCCP_ACKVEC_STATE_RECEIVED 0
-#define DCCP_ACKVEC_STATE_ECN_MARKED (1 << 6)
-#define DCCP_ACKVEC_STATE_NOT_RECEIVED (3 << 6)
+/* Threshold for coping with large bursts of losses */
+#define DCCPAV_BURST_THRESH (DCCPAV_MAX_ACKVEC_LEN / 8)
-#define DCCP_ACKVEC_STATE_MASK 0xC0 /* 11000000 */
-#define DCCP_ACKVEC_LEN_MASK 0x3F /* 00111111 */
+enum dccp_ackvec_states {
+ DCCPAV_RECEIVED = 0x00,
+ DCCPAV_ECN_MARKED = 0x40,
+ DCCPAV_RESERVED = 0x80,
+ DCCPAV_NOT_RECEIVED = 0xC0
+};
+#define DCCPAV_MAX_RUNLEN 0x3F
-/** struct dccp_ackvec - ack vector
- *
- * This data structure is the one defined in RFC 4340, Appendix A.
- *
- * @av_buf_head - circular buffer head
- * @av_buf_tail - circular buffer tail
- * @av_buf_ackno - ack # of the most recent packet acknowledgeable in the
- * buffer (i.e. %av_buf_head)
- * @av_buf_nonce - the one-bit sum of the ECN Nonces on all packets acked
- * by the buffer with State 0
- *
- * Additionally, the HC-Receiver must keep some information about the
- * Ack Vectors it has recently sent. For each packet sent carrying an
- * Ack Vector, it remembers four variables:
+static inline u8 dccp_ackvec_runlen(const u8 *cell)
+{
+ return *cell & DCCPAV_MAX_RUNLEN;
+}
+
+static inline u8 dccp_ackvec_state(const u8 *cell)
+{
+ return *cell & ~DCCPAV_MAX_RUNLEN;
+}
+
+/** struct dccp_ackvec - Ack Vector main data structure
*
- * @av_records - list of dccp_ackvec_record
- * @av_ack_nonce - the one-bit sum of the ECN Nonces for all State 0.
+ * This implements a fixed-size circular buffer within an array and is largely
+ * based on Appendix A of RFC 4340.
*
- * @av_time - the time in usecs
- * @av_buf - circular buffer of acknowledgeable packets
+ * @av_buf: circular buffer storage area
+ * @av_buf_head: head index; begin of live portion in @av_buf
+ * @av_buf_tail: tail index; first index _after_ the live portion in @av_buf
+ * @av_buf_ackno: highest seqno of acknowledgeable packet recorded in @av_buf
+ * @av_tail_ackno: lowest seqno of acknowledgeable packet recorded in @av_buf
+ * @av_buf_nonce: ECN nonce sums, each covering subsequent segments of up to
+ * %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf
+ * @av_overflow: if 1 then buf_head == buf_tail indicates buffer wraparound
+ * @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously)
*/
struct dccp_ackvec {
- u64 av_buf_ackno;
- struct list_head av_records;
- ktime_t av_time;
+ u8 av_buf[DCCPAV_MAX_ACKVEC_LEN];
u16 av_buf_head;
- u16 av_vec_len;
- u8 av_buf_nonce;
- u8 av_ack_nonce;
- u8 av_buf[DCCP_MAX_ACKVEC_LEN];
+ u16 av_buf_tail;
+ u64 av_buf_ackno:48;
+ u64 av_tail_ackno:48;
+ bool av_buf_nonce[DCCPAV_NUM_ACKVECS];
+ u8 av_overflow:1;
+ struct list_head av_records;
};
-/** struct dccp_ackvec_record - ack vector record
+/** struct dccp_ackvec_record - Records information about sent Ack Vectors
*
- * ACK vector record as defined in Appendix A of spec.
+ * These list entries define the additional information which the HC-Receiver
+ * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A.
*
- * The list is sorted by avr_ack_seqno
+ * @avr_node: the list node in @av_records
+ * @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on
+ * @avr_ack_ackno: the Ack number that this record/Ack Vector refers to
+ * @avr_ack_ptr: pointer into @av_buf where this record starts
+ * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending
+ * @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent
*
- * @avr_node - node in av_records
- * @avr_ack_seqno - sequence number of the packet this record was sent on
- * @avr_ack_ackno - sequence number being acknowledged
- * @avr_ack_ptr - pointer into av_buf where this record starts
- * @avr_ack_nonce - av_ack_nonce at the time this record was sent
- * @avr_sent_len - lenght of the record in av_buf
+ * The list as a whole is sorted in descending order by @avr_ack_seqno.
*/
struct dccp_ackvec_record {
struct list_head avr_node;
- u64 avr_ack_seqno;
- u64 avr_ack_ackno;
+ u64 avr_ack_seqno:48;
+ u64 avr_ack_ackno:48;
u16 avr_ack_ptr;
- u16 avr_sent_len;
- u8 avr_ack_nonce;
+ u8 avr_ack_runlen;
+ u8 avr_ack_nonce:1;
};
-struct sock;
-struct sk_buff;
-
extern int dccp_ackvec_init(void);
extern void dccp_ackvec_exit(void);
extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
extern void dccp_ackvec_free(struct dccp_ackvec *av);
-extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
- const u64 ackno, const u8 state);
-
-extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
- struct sock *sk, const u64 ackno);
-extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
- u64 *ackno, const u8 opt,
- const u8 *value, const u8 len);
+extern void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb);
+extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
+extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno);
+extern u16 dccp_ackvec_buflen(const struct dccp_ackvec *av);
-extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
-
-static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
+static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
{
- return av->av_vec_len;
+ return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail;
}
+
+/**
+ * struct dccp_ackvec_parsed - Record offsets of Ack Vectors in skb
+ * @vec: start of vector (offset into skb)
+ * @len: length of @vec
+ * @nonce: whether @vec had an ECN nonce of 0 or 1
+ * @node: FIFO - arranged in descending order of ack_ackno
+ * This structure is used by CCIDs to access Ack Vectors in a received skb.
+ */
+struct dccp_ackvec_parsed {
+ u8 *vec,
+ len,
+ nonce:1;
+ struct list_head node;
+};
+
+extern int dccp_ackvec_parsed_add(struct list_head *head,
+ u8 *vec, u8 len, u8 nonce);
+extern void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks);
#endif /* _ACKVEC_H */
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