1 #ifndef _ACKVEC_H 2 #define _ACKVEC_H 3 /* 4 * net/dccp/ackvec.h 5 * 6 * An implementation of Ack Vectors for the DCCP protocol 7 * Copyright (c) 2007 University of Aberdeen, Scotland, UK 8 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com> 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 */ 13 14 #include <linux/dccp.h> 15 #include <linux/compiler.h> 16 #include <linux/list.h> 17 #include <linux/types.h> 18 19 /* 20 * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN, 21 * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1 22 * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives 23 * more headroom if Ack Ratio is higher or when the sender acknowledges slowly. 24 * The maximum value is bounded by the u16 types for indices and functions. 25 */ 26 #define DCCPAV_NUM_ACKVECS 2 27 #define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS) 28 29 /* Estimated minimum average Ack Vector length - used for updating MPS */ 30 #define DCCPAV_MIN_OPTLEN 16 31 32 /* Threshold for coping with large bursts of losses */ 33 #define DCCPAV_BURST_THRESH (DCCPAV_MAX_ACKVEC_LEN / 8) 34 35 enum dccp_ackvec_states { 36 DCCPAV_RECEIVED = 0x00, 37 DCCPAV_ECN_MARKED = 0x40, 38 DCCPAV_RESERVED = 0x80, 39 DCCPAV_NOT_RECEIVED = 0xC0 40 }; 41 #define DCCPAV_MAX_RUNLEN 0x3F 42 43 static inline u8 dccp_ackvec_runlen(const u8 *cell) 44 { 45 return *cell & DCCPAV_MAX_RUNLEN; 46 } 47 48 static inline u8 dccp_ackvec_state(const u8 *cell) 49 { 50 return *cell & ~DCCPAV_MAX_RUNLEN; 51 } 52 53 /** 54 * struct dccp_ackvec - Ack Vector main data structure 55 * 56 * This implements a fixed-size circular buffer within an array and is largely 57 * based on Appendix A of RFC 4340. 58 * 59 * @av_buf: circular buffer storage area 60 * @av_buf_head: head index; begin of live portion in @av_buf 61 * @av_buf_tail: tail index; first index _after_ the live portion in @av_buf 62 * @av_buf_ackno: highest seqno of acknowledgeable packet recorded in @av_buf 63 * @av_tail_ackno: lowest seqno of acknowledgeable packet recorded in @av_buf 64 * @av_buf_nonce: ECN nonce sums, each covering subsequent segments of up to 65 * %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf 66 * @av_overflow: if 1 then buf_head == buf_tail indicates buffer wraparound 67 * @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously) 68 */ 69 struct dccp_ackvec { 70 u8 av_buf[DCCPAV_MAX_ACKVEC_LEN]; 71 u16 av_buf_head; 72 u16 av_buf_tail; 73 u64 av_buf_ackno:48; 74 u64 av_tail_ackno:48; 75 bool av_buf_nonce[DCCPAV_NUM_ACKVECS]; 76 u8 av_overflow:1; 77 struct list_head av_records; 78 }; 79 80 /** 81 * struct dccp_ackvec_record - Records information about sent Ack Vectors 82 * 83 * These list entries define the additional information which the HC-Receiver 84 * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A. 85 * 86 * @avr_node: the list node in @av_records 87 * @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on 88 * @avr_ack_ackno: the Ack number that this record/Ack Vector refers to 89 * @avr_ack_ptr: pointer into @av_buf where this record starts 90 * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending 91 * @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent 92 * 93 * The list as a whole is sorted in descending order by @avr_ack_seqno. 94 */ 95 struct dccp_ackvec_record { 96 struct list_head avr_node; 97 u64 avr_ack_seqno:48; 98 u64 avr_ack_ackno:48; 99 u16 avr_ack_ptr; 100 u8 avr_ack_runlen; 101 u8 avr_ack_nonce:1; 102 }; 103 104 int dccp_ackvec_init(void); 105 void dccp_ackvec_exit(void); 106 107 struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority); 108 void dccp_ackvec_free(struct dccp_ackvec *av); 109 110 void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb); 111 int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum); 112 void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno); 113 u16 dccp_ackvec_buflen(const struct dccp_ackvec *av); 114 115 static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av) 116 { 117 return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail; 118 } 119 120 /** 121 * struct dccp_ackvec_parsed - Record offsets of Ack Vectors in skb 122 * @vec: start of vector (offset into skb) 123 * @len: length of @vec 124 * @nonce: whether @vec had an ECN nonce of 0 or 1 125 * @node: FIFO - arranged in descending order of ack_ackno 126 * 127 * This structure is used by CCIDs to access Ack Vectors in a received skb. 128 */ 129 struct dccp_ackvec_parsed { 130 u8 *vec, 131 len, 132 nonce:1; 133 struct list_head node; 134 }; 135 136 int dccp_ackvec_parsed_add(struct list_head *head, u8 *vec, u8 len, u8 nonce); 137 void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks); 138 #endif /* _ACKVEC_H */ 139