xref: /linux/net/dccp/ackvec.h (revision a47c5104)
1 #ifndef _ACKVEC_H
2 #define _ACKVEC_H
3 /*
4  *  net/dccp/ackvec.h
5  *
6  *  An implementation of the DCCP protocol
7  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com>
8  *
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/compiler.h>
15 #include <linux/ktime.h>
16 #include <linux/list.h>
17 #include <linux/types.h>
18 
19 /* Read about the ECN nonce to see why it is 253 */
20 #define DCCP_MAX_ACKVEC_OPT_LEN 253
21 /* We can spread an ack vector across multiple options */
22 #define DCCP_MAX_ACKVEC_LEN (DCCP_MAX_ACKVEC_OPT_LEN * 2)
23 
24 #define DCCP_ACKVEC_STATE_RECEIVED	0
25 #define DCCP_ACKVEC_STATE_ECN_MARKED	(1 << 6)
26 #define DCCP_ACKVEC_STATE_NOT_RECEIVED	(3 << 6)
27 
28 #define DCCP_ACKVEC_STATE_MASK		0xC0 /* 11000000 */
29 #define DCCP_ACKVEC_LEN_MASK		0x3F /* 00111111 */
30 
31 /** struct dccp_ackvec - ack vector
32  *
33  * This data structure is the one defined in RFC 4340, Appendix A.
34  *
35  * @av_buf_head - circular buffer head
36  * @av_buf_tail - circular buffer tail
37  * @av_buf_ackno - ack # of the most recent packet acknowledgeable in the
38  *		       buffer (i.e. %av_buf_head)
39  * @av_buf_nonce - the one-bit sum of the ECN Nonces on all packets acked
40  * 		       by the buffer with State 0
41  *
42  * Additionally, the HC-Receiver must keep some information about the
43  * Ack Vectors it has recently sent. For each packet sent carrying an
44  * Ack Vector, it remembers four variables:
45  *
46  * @av_records - list of dccp_ackvec_record
47  * @av_ack_nonce - the one-bit sum of the ECN Nonces for all State 0.
48  *
49  * @av_time - the time in usecs
50  * @av_buf - circular buffer of acknowledgeable packets
51  */
52 struct dccp_ackvec {
53 	u64			av_buf_ackno;
54 	struct list_head	av_records;
55 	ktime_t			av_time;
56 	u16			av_buf_head;
57 	u16			av_vec_len;
58 	u8			av_buf_nonce;
59 	u8			av_ack_nonce;
60 	u8			av_buf[DCCP_MAX_ACKVEC_LEN];
61 };
62 
63 /** struct dccp_ackvec_record - ack vector record
64  *
65  * ACK vector record as defined in Appendix A of spec.
66  *
67  * The list is sorted by avr_ack_seqno
68  *
69  * @avr_node - node in av_records
70  * @avr_ack_seqno - sequence number of the packet this record was sent on
71  * @avr_ack_ackno - sequence number being acknowledged
72  * @avr_ack_ptr - pointer into av_buf where this record starts
73  * @avr_ack_nonce - av_ack_nonce at the time this record was sent
74  * @avr_sent_len - lenght of the record in av_buf
75  */
76 struct dccp_ackvec_record {
77 	struct list_head avr_node;
78 	u64		 avr_ack_seqno;
79 	u64		 avr_ack_ackno;
80 	u16		 avr_ack_ptr;
81 	u16		 avr_sent_len;
82 	u8		 avr_ack_nonce;
83 };
84 
85 struct sock;
86 struct sk_buff;
87 
88 #ifdef CONFIG_IP_DCCP_ACKVEC
89 extern int dccp_ackvec_init(void);
90 extern void dccp_ackvec_exit(void);
91 
92 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
93 extern void dccp_ackvec_free(struct dccp_ackvec *av);
94 
95 extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
96 			   const u64 ackno, const u8 state);
97 
98 extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
99 					struct sock *sk, const u64 ackno);
100 extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
101 			     u64 *ackno, const u8 opt,
102 			     const u8 *value, const u8 len);
103 
104 extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
105 
106 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
107 {
108 	return av->av_vec_len;
109 }
110 #else /* CONFIG_IP_DCCP_ACKVEC */
111 static inline int dccp_ackvec_init(void)
112 {
113 	return 0;
114 }
115 
116 static inline void dccp_ackvec_exit(void)
117 {
118 }
119 
120 static inline struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
121 {
122 	return NULL;
123 }
124 
125 static inline void dccp_ackvec_free(struct dccp_ackvec *av)
126 {
127 }
128 
129 static inline int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
130 				  const u64 ackno, const u8 state)
131 {
132 	return -1;
133 }
134 
135 static inline void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
136 					       struct sock *sk, const u64 ackno)
137 {
138 }
139 
140 static inline int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
141 				    const u64 *ackno, const u8 opt,
142 				    const u8 *value, const u8 len)
143 {
144 	return -1;
145 }
146 
147 static inline int dccp_insert_option_ackvec(const struct sock *sk,
148 					    const struct sk_buff *skb)
149 {
150 	return -1;
151 }
152 
153 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
154 {
155 	return 0;
156 }
157 #endif /* CONFIG_IP_DCCP_ACKVEC */
158 #endif /* _ACKVEC_H */
159