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Diffstat (limited to 'net/dccp/ackvec.h')
| -rw-r--r-- | net/dccp/ackvec.h | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h new file mode 100644 index 000000000..3284bfa98 --- /dev/null +++ b/net/dccp/ackvec.h @@ -0,0 +1,138 @@ +#ifndef _ACKVEC_H +#define _ACKVEC_H +/* + * net/dccp/ackvec.h + * + * 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/list.h> +#include <linux/types.h> + +/* + * 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 + +/* Threshold for coping with large bursts of losses */ +#define DCCPAV_BURST_THRESH (DCCPAV_MAX_ACKVEC_LEN / 8) + +enum dccp_ackvec_states { + DCCPAV_RECEIVED = 0x00, + DCCPAV_ECN_MARKED = 0x40, + DCCPAV_RESERVED = 0x80, + DCCPAV_NOT_RECEIVED = 0xC0 +}; +#define DCCPAV_MAX_RUNLEN 0x3F + +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 + * + * This implements a fixed-size circular buffer within an array and is largely + * based on Appendix A of RFC 4340. + * + * @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 { + u8 av_buf[DCCPAV_MAX_ACKVEC_LEN]; + u16 av_buf_head; + 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 - Records information about sent Ack Vectors + * + * These list entries define the additional information which the HC-Receiver + * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A. + * + * @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 + * + * 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:48; + u64 avr_ack_ackno:48; + u16 avr_ack_ptr; + u8 avr_ack_runlen; + u8 avr_ack_nonce:1; +}; + +int dccp_ackvec_init(void); +void dccp_ackvec_exit(void); + +struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority); +void dccp_ackvec_free(struct dccp_ackvec *av); + +void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb); +int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum); +void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno); +u16 dccp_ackvec_buflen(const struct dccp_ackvec *av); + +static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av) +{ + 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; +}; + +int dccp_ackvec_parsed_add(struct list_head *head, u8 *vec, u8 len, u8 nonce); +void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks); +#endif /* _ACKVEC_H */ |