1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 #ifndef _ACKVEC_H 3 #define _ACKVEC_H 4 /* 5 * net/dccp/ackvec.h 6 * 7 * An implementation of Ack Vectors for the DCCP protocol 8 * Copyright (c) 2007 University of Aberdeen, Scotland, UK 9 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com> 10 */ 11 12 #include <linux/dccp.h> 13 #include <linux/compiler.h> 14 #include <linux/list.h> 15 #include <linux/types.h> 16 17 /* 18 * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN, 19 * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1 20 * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives 21 * more headroom if Ack Ratio is higher or when the sender acknowledges slowly. 22 * The maximum value is bounded by the u16 types for indices and functions. 23 */ 24 #define DCCPAV_NUM_ACKVECS 2 25 #define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS) 26 27 /* Estimated minimum average Ack Vector length - used for updating MPS */ 28 #define DCCPAV_MIN_OPTLEN 16 29 30 /* Threshold for coping with large bursts of losses */ 31 #define DCCPAV_BURST_THRESH (DCCPAV_MAX_ACKVEC_LEN / 8) 32 33 enum dccp_ackvec_states { 34 DCCPAV_RECEIVED = 0x00, 35 DCCPAV_ECN_MARKED = 0x40, 36 DCCPAV_RESERVED = 0x80, 37 DCCPAV_NOT_RECEIVED = 0xC0 38 }; 39 #define DCCPAV_MAX_RUNLEN 0x3F 40 41 static inline u8 dccp_ackvec_runlen(const u8 *cell) 42 { 43 return *cell & DCCPAV_MAX_RUNLEN; 44 } 45 46 static inline u8 dccp_ackvec_state(const u8 *cell) 47 { 48 return *cell & ~DCCPAV_MAX_RUNLEN; 49 } 50 51 /** 52 * struct dccp_ackvec - Ack Vector main data structure 53 * 54 * This implements a fixed-size circular buffer within an array and is largely 55 * based on Appendix A of RFC 4340. 56 * 57 * @av_buf: circular buffer storage area 58 * @av_buf_head: head index; begin of live portion in @av_buf 59 * @av_buf_tail: tail index; first index _after_ the live portion in @av_buf 60 * @av_buf_ackno: highest seqno of acknowledgeable packet recorded in @av_buf 61 * @av_tail_ackno: lowest seqno of acknowledgeable packet recorded in @av_buf 62 * @av_buf_nonce: ECN nonce sums, each covering subsequent segments of up to 63 * %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf 64 * @av_overflow: if 1 then buf_head == buf_tail indicates buffer wraparound 65 * @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously) 66 */ 67 struct dccp_ackvec { 68 u8 av_buf[DCCPAV_MAX_ACKVEC_LEN]; 69 u16 av_buf_head; 70 u16 av_buf_tail; 71 u64 av_buf_ackno:48; 72 u64 av_tail_ackno:48; 73 bool av_buf_nonce[DCCPAV_NUM_ACKVECS]; 74 u8 av_overflow:1; 75 struct list_head av_records; 76 }; 77 78 /** 79 * struct dccp_ackvec_record - Records information about sent Ack Vectors 80 * 81 * These list entries define the additional information which the HC-Receiver 82 * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A. 83 * 84 * @avr_node: the list node in @av_records 85 * @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on 86 * @avr_ack_ackno: the Ack number that this record/Ack Vector refers to 87 * @avr_ack_ptr: pointer into @av_buf where this record starts 88 * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending 89 * @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent 90 * 91 * The list as a whole is sorted in descending order by @avr_ack_seqno. 92 */ 93 struct dccp_ackvec_record { 94 struct list_head avr_node; 95 u64 avr_ack_seqno:48; 96 u64 avr_ack_ackno:48; 97 u16 avr_ack_ptr; 98 u8 avr_ack_runlen; 99 u8 avr_ack_nonce:1; 100 }; 101 102 int dccp_ackvec_init(void); 103 void dccp_ackvec_exit(void); 104 105 struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority); 106 void dccp_ackvec_free(struct dccp_ackvec *av); 107 108 void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb); 109 int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum); 110 void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno); 111 u16 dccp_ackvec_buflen(const struct dccp_ackvec *av); 112 113 static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av) 114 { 115 return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail; 116 } 117 118 /** 119 * struct dccp_ackvec_parsed - Record offsets of Ack Vectors in skb 120 * @vec: start of vector (offset into skb) 121 * @len: length of @vec 122 * @nonce: whether @vec had an ECN nonce of 0 or 1 123 * @node: FIFO - arranged in descending order of ack_ackno 124 * 125 * This structure is used by CCIDs to access Ack Vectors in a received skb. 126 */ 127 struct dccp_ackvec_parsed { 128 u8 *vec, 129 len, 130 nonce:1; 131 struct list_head node; 132 }; 133 134 int dccp_ackvec_parsed_add(struct list_head *head, u8 *vec, u8 len, u8 nonce); 135 void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks); 136 #endif /* _ACKVEC_H */ 137