1 | /* |
2 | * rdbx.h |
3 | * |
4 | * replay database with extended packet indices, using a rollover counter |
5 | * |
6 | * David A. McGrew |
7 | * Cisco Systems, Inc. |
8 | * |
9 | */ |
10 | |
11 | #ifndef RDBX_H |
12 | #define RDBX_H |
13 | |
14 | #include "datatypes.h" |
15 | #include "err.h" |
16 | |
17 | /* #define ROC_TEST */ |
18 | |
19 | #ifndef ROC_TEST |
20 | |
21 | typedef uint16_t sequence_number_t; /* 16 bit sequence number */ |
22 | typedef uint32_t rollover_counter_t; /* 32 bit rollover counter */ |
23 | |
24 | #else /* use small seq_num and roc datatypes for testing purposes */ |
25 | |
26 | typedef unsigned char sequence_number_t; /* 8 bit sequence number */ |
27 | typedef uint16_t rollover_counter_t; /* 16 bit rollover counter */ |
28 | |
29 | #endif |
30 | |
31 | #define seq_num_median (1 << (8*sizeof(sequence_number_t) - 1)) |
32 | #define seq_num_max (1 << (8*sizeof(sequence_number_t))) |
33 | |
34 | /* |
35 | * An xtd_seq_num_t is a 64-bit unsigned integer used as an 'extended' |
36 | * sequence number. |
37 | */ |
38 | |
39 | typedef uint64_t xtd_seq_num_t; |
40 | |
41 | |
42 | /* |
43 | * An rdbx_t is a replay database with extended range; it uses an |
44 | * xtd_seq_num_t and a bitmask of recently received indices. |
45 | */ |
46 | |
47 | typedef struct { |
48 | xtd_seq_num_t index; |
49 | bitvector_t bitmask; |
50 | } rdbx_t; |
51 | |
52 | |
53 | /* |
54 | * rdbx_init(rdbx_ptr, ws) |
55 | * |
56 | * initializes the rdbx pointed to by its argument with the window size ws, |
57 | * setting the rollover counter and sequence number to zero |
58 | */ |
59 | |
60 | err_status_t |
61 | rdbx_init(rdbx_t *rdbx, unsigned long ws); |
62 | |
63 | |
64 | /* |
65 | * rdbx_dealloc(rdbx_ptr) |
66 | * |
67 | * frees memory associated with the rdbx |
68 | */ |
69 | |
70 | err_status_t |
71 | rdbx_dealloc(rdbx_t *rdbx); |
72 | |
73 | |
74 | /* |
75 | * rdbx_estimate_index(rdbx, guess, s) |
76 | * |
77 | * given an rdbx and a sequence number s (from a newly arrived packet), |
78 | * sets the contents of *guess to contain the best guess of the packet |
79 | * index to which s corresponds, and returns the difference between |
80 | * *guess and the locally stored synch info |
81 | */ |
82 | |
83 | int |
84 | rdbx_estimate_index(const rdbx_t *rdbx, |
85 | xtd_seq_num_t *guess, |
86 | sequence_number_t s); |
87 | |
88 | /* |
89 | * rdbx_check(rdbx, delta); |
90 | * |
91 | * rdbx_check(&r, delta) checks to see if the xtd_seq_num_t |
92 | * which is at rdbx->window_start + delta is in the rdb |
93 | * |
94 | */ |
95 | |
96 | err_status_t |
97 | rdbx_check(const rdbx_t *rdbx, int difference); |
98 | |
99 | /* |
100 | * replay_add_index(rdbx, delta) |
101 | * |
102 | * adds the xtd_seq_num_t at rdbx->window_start + delta to replay_db |
103 | * (and does *not* check if that xtd_seq_num_t appears in db) |
104 | * |
105 | * this function should be called *only* after replay_check has |
106 | * indicated that the index does not appear in the rdbx, and a mutex |
107 | * should protect the rdbx between these calls if necessary. |
108 | */ |
109 | |
110 | err_status_t |
111 | rdbx_add_index(rdbx_t *rdbx, int delta); |
112 | |
113 | |
114 | /* |
115 | * rdbx_set_roc(rdbx, roc) initalizes the rdbx_t at the location rdbx |
116 | * to have the rollover counter value roc. If that value is less than |
117 | * the current rollover counter value, then the function returns |
118 | * err_status_replay_old; otherwise, err_status_ok is returned. |
119 | * |
120 | */ |
121 | |
122 | err_status_t |
123 | rdbx_set_roc(rdbx_t *rdbx, uint32_t roc); |
124 | |
125 | /* |
126 | * rdbx_get_roc(rdbx) returns the value of the rollover counter for |
127 | * the rdbx_t pointed to by rdbx |
128 | * |
129 | */ |
130 | |
131 | xtd_seq_num_t |
132 | rdbx_get_packet_index(const rdbx_t *rdbx); |
133 | |
134 | /* |
135 | * xtd_seq_num_t functions - these are *internal* functions of rdbx, and |
136 | * shouldn't be used to manipulate rdbx internal values. use the rdbx |
137 | * api instead! |
138 | */ |
139 | |
140 | /* |
141 | * rdbx_get_ws(rdbx_ptr) |
142 | * |
143 | * gets the window size which was used to initialize the rdbx |
144 | */ |
145 | |
146 | unsigned long |
147 | rdbx_get_window_size(const rdbx_t *rdbx); |
148 | |
149 | |
150 | /* index_init(&pi) initializes a packet index pi (sets it to zero) */ |
151 | |
152 | void |
153 | index_init(xtd_seq_num_t *pi); |
154 | |
155 | /* index_advance(&pi, s) advances a xtd_seq_num_t forward by s */ |
156 | |
157 | void |
158 | index_advance(xtd_seq_num_t *pi, sequence_number_t s); |
159 | |
160 | |
161 | /* |
162 | * index_guess(local, guess, s) |
163 | * |
164 | * given a xtd_seq_num_t local (which represents the highest |
165 | * known-to-be-good index) and a sequence number s (from a newly |
166 | * arrived packet), sets the contents of *guess to contain the best |
167 | * guess of the packet index to which s corresponds, and returns the |
168 | * difference between *guess and *local |
169 | */ |
170 | |
171 | int |
172 | index_guess(const xtd_seq_num_t *local, |
173 | xtd_seq_num_t *guess, |
174 | sequence_number_t s); |
175 | |
176 | |
177 | #endif /* RDBX_H */ |
178 | |
179 | |
180 | |
181 | |
182 | |
183 | |
184 | |
185 | |
186 | |
187 | |